xml.html revision 99906ada06c58ef41af5dea93f5e2ba1b4d19ff6
1<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" 2 "http://www.w3.org/TR/html4/loose.dtd"> 3<html> 4<head> 5 <title>The XML C parser and toolkit of Gnome</title> 6 <meta name="GENERATOR" content="amaya 5.1"> 7 <meta http-equiv="Content-Type" content="text/html"> 8</head> 9 10<body bgcolor="#ffffff"> 11<h1 align="center">The XML C parser and toolkit of Gnome</h1> 12 13<h1>Note: this is the flat content of the <a href="index.html">web 14site</a></h1> 15 16<h1 style="text-align: center">libxml, a.k.a. gnome-xml</h1> 17 18<p></p> 19 20<p 21style="text-align: right; font-style: italic; font-size: 10pt">"Programming 22with libxml2 is like the thrilling embrace of an exotic stranger." <a 23href="http://diveintomark.org/archives/2004/02/18/libxml2">Mark 24Pilgrim</a></p> 25 26<p>Libxml2 is the XML C parser and toolkit developed for the Gnome project 27(but usable outside of the Gnome platform), it is free software available 28under the <a href="http://www.opensource.org/licenses/mit-license.html">MIT 29License</a>. XML itself is a metalanguage to design markup languages, i.e. 30text language where semantic and structure are added to the content using 31extra "markup" information enclosed between angle brackets. HTML is the most 32well-known markup language. Though the library is written in C <a 33href="python.html">a variety of language bindings</a> make it available in 34other environments.</p> 35 36<p>Libxml2 is known to be very portable, the library should build and work 37without serious troubles on a variety of systems (Linux, Unix, Windows, 38CygWin, MacOS, MacOS X, RISC Os, OS/2, VMS, QNX, MVS, ...)</p> 39 40<p>Libxml2 implements a number of existing standards related to markup 41languages:</p> 42<ul> 43 <li>the XML standard: <a 44 href="http://www.w3.org/TR/REC-xml">http://www.w3.org/TR/REC-xml</a></li> 45 <li>Namespaces in XML: <a 46 href="http://www.w3.org/TR/REC-xml-names/">http://www.w3.org/TR/REC-xml-names/</a></li> 47 <li>XML Base: <a 48 href="http://www.w3.org/TR/xmlbase/">http://www.w3.org/TR/xmlbase/</a></li> 49 <li><a href="http://www.cis.ohio-state.edu/rfc/rfc2396.txt">RFC 2396</a> : 50 Uniform Resource Identifiers <a 51 href="http://www.ietf.org/rfc/rfc2396.txt">http://www.ietf.org/rfc/rfc2396.txt</a></li> 52 <li>XML Path Language (XPath) 1.0: <a 53 href="http://www.w3.org/TR/xpath">http://www.w3.org/TR/xpath</a></li> 54 <li>HTML4 parser: <a 55 href="http://www.w3.org/TR/html401/">http://www.w3.org/TR/html401/</a></li> 56 <li>XML Pointer Language (XPointer) Version 1.0: <a 57 href="http://www.w3.org/TR/xptr">http://www.w3.org/TR/xptr</a></li> 58 <li>XML Inclusions (XInclude) Version 1.0: <a 59 href="http://www.w3.org/TR/xinclude/">http://www.w3.org/TR/xinclude/</a></li> 60 <li>ISO-8859-x encodings, as well as <a 61 href="http://www.cis.ohio-state.edu/rfc/rfc2044.txt">rfc2044</a> [UTF-8] 62 and <a href="http://www.cis.ohio-state.edu/rfc/rfc2781.txt">rfc2781</a> 63 [UTF-16] Unicode encodings, and more if using iconv support</li> 64 <li>part of SGML Open Technical Resolution TR9401:1997</li> 65 <li>XML Catalogs Working Draft 06 August 2001: <a 66 href="http://www.oasis-open.org/committees/entity/spec-2001-08-06.html">http://www.oasis-open.org/committees/entity/spec-2001-08-06.html</a></li> 67 <li>Canonical XML Version 1.0: <a 68 href="http://www.w3.org/TR/xml-c14n">http://www.w3.org/TR/xml-c14n</a> 69 and the Exclusive XML Canonicalization CR draft <a 70 href="http://www.w3.org/TR/xml-exc-c14n">http://www.w3.org/TR/xml-exc-c14n</a></li> 71 <li>Relax NG, ISO/IEC 19757-2:2003, <a 72 href="http://www.oasis-open.org/committees/relax-ng/spec-20011203.html">http://www.oasis-open.org/committees/relax-ng/spec-20011203.html</a></li> 73 <li>W3C XML Schemas Part 2: Datatypes <a 74 href="http://www.w3.org/TR/2001/REC-xmlschema-2-20010502/">REC 02 May 75 2001</a></li> 76 <li>W3C <a href="http://www.w3.org/TR/xml-id/">xml:id</a> Working Draft 7 77 April 2004</li> 78</ul> 79 80<p>In most cases libxml2 tries to implement the specifications in a 81relatively strictly compliant way. As of release 2.4.16, libxml2 passed all 821800+ tests from the <a 83href="http://www.oasis-open.org/committees/xml-conformance/">OASIS XML Tests 84Suite</a>.</p> 85 86<p>To some extent libxml2 provides support for the following additional 87specifications but doesn't claim to implement them completely:</p> 88<ul> 89 <li>Document Object Model (DOM) <a 90 href="http://www.w3.org/TR/DOM-Level-2-Core/">http://www.w3.org/TR/DOM-Level-2-Core/</a> 91 the document model, but it doesn't implement the API itself, gdome2 does 92 this on top of libxml2</li> 93 <li><a href="http://www.cis.ohio-state.edu/rfc/rfc959.txt">RFC 959</a> : 94 libxml2 implements a basic FTP client code</li> 95 <li><a href="http://www.cis.ohio-state.edu/rfc/rfc1945.txt">RFC 1945</a> : 96 HTTP/1.0, again a basic HTTP client code</li> 97 <li>SAX: a SAX2 like interface and a minimal SAX1 implementation compatible 98 with early expat versions</li> 99</ul> 100 101<p>A partial implementation of <a 102href="http://www.w3.org/TR/2001/REC-xmlschema-1-20010502/">XML Schemas Part 1031: Structure</a> is being worked on but it would be far too early to make any 104conformance statement about it at the moment.</p> 105 106<p>Separate documents:</p> 107<ul> 108 <li><a href="http://xmlsoft.org/XSLT/">the libxslt page</a> providing an 109 implementation of XSLT 1.0 and common extensions like EXSLT for 110 libxml2</li> 111 <li><a href="http://www.cs.unibo.it/~casarini/gdome2/">the gdome2 page</a> 112 : a standard DOM2 implementation for libxml2</li> 113 <li><a href="http://www.aleksey.com/xmlsec/">the XMLSec page</a>: an 114 implementation of <a href="http://www.w3.org/TR/xmldsig-core/">W3C XML 115 Digital Signature</a> for libxml2</li> 116 <li>also check the related links section below for more related and active 117 projects.</li> 118</ul> 119<!----------------<p>Results of the <a 120href="http://xmlbench.sourceforge.net/results/benchmark/index.html">xmlbench 121benchmark</a> on sourceforge February 2004 (smaller is better):</p> 122 123<p align="center"><img src="benchmark.png" 124alt="benchmark results for Expat Xerces libxml2 Oracle and Sun toolkits"></p> 125--------------> 126 127 128<p>Logo designed by <a href="mailto:liyanage@access.ch">Marc Liyanage</a>.</p> 129 130<h2><a name="Introducti">Introduction</a></h2> 131 132<p>This document describes libxml, the <a 133href="http://www.w3.org/XML/">XML</a> C parser and toolkit developed for the 134<a href="http://www.gnome.org/">Gnome</a> project. <a 135href="http://www.w3.org/XML/">XML is a standard</a> for building tag-based 136structured documents/data.</p> 137 138<p>Here are some key points about libxml:</p> 139<ul> 140 <li>Libxml2 exports Push (progressive) and Pull (blocking) type parser 141 interfaces for both XML and HTML.</li> 142 <li>Libxml2 can do DTD validation at parse time, using a parsed document 143 instance, or with an arbitrary DTD.</li> 144 <li>Libxml2 includes complete <a 145 href="http://www.w3.org/TR/xpath">XPath</a>, <a 146 href="http://www.w3.org/TR/xptr">XPointer</a> and <a 147 href="http://www.w3.org/TR/xinclude">XInclude</a> implementations.</li> 148 <li>It is written in plain C, making as few assumptions as possible, and 149 sticking closely to ANSI C/POSIX for easy embedding. Works on 150 Linux/Unix/Windows, ported to a number of other platforms.</li> 151 <li>Basic support for HTTP and FTP client allowing applications to fetch 152 remote resources.</li> 153 <li>The design is modular, most of the extensions can be compiled out.</li> 154 <li>The internal document representation is as close as possible to the <a 155 href="http://www.w3.org/DOM/">DOM</a> interfaces.</li> 156 <li>Libxml2 also has a <a 157 href="http://www.megginson.com/SAX/index.html">SAX like interface</a>; 158 the interface is designed to be compatible with <a 159 href="http://www.jclark.com/xml/expat.html">Expat</a>.</li> 160 <li>This library is released under the <a 161 href="http://www.opensource.org/licenses/mit-license.html">MIT 162 License</a>. See the Copyright file in the distribution for the precise 163 wording.</li> 164</ul> 165 166<p>Warning: unless you are forced to because your application links with a 167Gnome-1.X library requiring it, <strong><span 168style="background-color: #FF0000">Do Not Use libxml1</span></strong>, use 169libxml2</p> 170 171<h2><a name="FAQ">FAQ</a></h2> 172 173<p>Table of Contents:</p> 174<ul> 175 <li><a href="FAQ.html#License">License(s)</a></li> 176 <li><a href="FAQ.html#Installati">Installation</a></li> 177 <li><a href="FAQ.html#Compilatio">Compilation</a></li> 178 <li><a href="FAQ.html#Developer">Developer corner</a></li> 179</ul> 180 181<h3><a name="License">License</a>(s)</h3> 182<ol> 183 <li><em>Licensing Terms for libxml</em> 184 <p>libxml2 is released under the <a 185 href="http://www.opensource.org/licenses/mit-license.html">MIT 186 License</a>; see the file Copyright in the distribution for the precise 187 wording</p> 188 </li> 189 <li><em>Can I embed libxml2 in a proprietary application ?</em> 190 <p>Yes. The MIT License allows you to keep proprietary the changes you 191 made to libxml, but it would be graceful to send-back bug fixes and 192 improvements as patches for possible incorporation in the main 193 development tree.</p> 194 </li> 195</ol> 196 197<h3><a name="Installati">Installation</a></h3> 198<ol> 199 <li><strong><span style="background-color: #FF0000">Do Not Use 200 libxml1</span></strong>, use libxml2</li> 201 <li><em>Where can I get libxml</em> ? 202 <p>The original distribution comes from <a 203 href="ftp://rpmfind.net/pub/libxml/">rpmfind.net</a> or <a 204 href="ftp://ftp.gnome.org/pub/GNOME/sources/libxml2/2.6/">gnome.org</a></p> 205 <p>Most Linux and BSD distributions include libxml, this is probably the 206 safer way for end-users to use libxml.</p> 207 <p>David Doolin provides precompiled Windows versions at <a 208 href="http://www.ce.berkeley.edu/~doolin/code/libxmlwin32/ ">http://www.ce.berkeley.edu/~doolin/code/libxmlwin32/</a></p> 209 </li> 210 <li><em>I see libxml and libxml2 releases, which one should I install ?</em> 211 <ul> 212 <li>If you are not constrained by backward compatibility issues with 213 existing applications, install libxml2 only</li> 214 <li>If you are not doing development, you can safely install both. 215 Usually the packages <a 216 href="http://rpmfind.net/linux/RPM/libxml.html">libxml</a> and <a 217 href="http://rpmfind.net/linux/RPM/libxml2.html">libxml2</a> are 218 compatible (this is not the case for development packages).</li> 219 <li>If you are a developer and your system provides separate packaging 220 for shared libraries and the development components, it is possible 221 to install libxml and libxml2, and also <a 222 href="http://rpmfind.net/linux/RPM/libxml-devel.html">libxml-devel</a> 223 and <a 224 href="http://rpmfind.net/linux/RPM/libxml2-devel.html">libxml2-devel</a> 225 too for libxml2 >= 2.3.0</li> 226 <li>If you are developing a new application, please develop against 227 libxml2(-devel)</li> 228 </ul> 229 </li> 230 <li><em>I can't install the libxml package, it conflicts with libxml0</em> 231 <p>You probably have an old libxml0 package used to provide the shared 232 library for libxml.so.0, you can probably safely remove it. The libxml 233 packages provided on <a 234 href="ftp://rpmfind.net/pub/libxml/">rpmfind.net</a> provide 235 libxml.so.0</p> 236 </li> 237 <li><em>I can't install the libxml(2) RPM package due to failed 238 dependencies</em> 239 <p>The most generic solution is to re-fetch the latest src.rpm , and 240 rebuild it locally with</p> 241 <p><code>rpm --rebuild libxml(2)-xxx.src.rpm</code>.</p> 242 <p>If everything goes well it will generate two binary rpm packages (one 243 providing the shared libs and xmllint, and the other one, the -devel 244 package, providing includes, static libraries and scripts needed to build 245 applications with libxml(2)) that you can install locally.</p> 246 </li> 247</ol> 248 249<h3><a name="Compilatio">Compilation</a></h3> 250<ol> 251 <li><em>What is the process to compile libxml2 ?</em> 252 <p>As most UNIX libraries libxml2 follows the "standard":</p> 253 <p><code>gunzip -c xxx.tar.gz | tar xvf -</code></p> 254 <p><code>cd libxml-xxxx</code></p> 255 <p><code>/configure --help</code></p> 256 <p>to see the options, then the compilation/installation proper</p> 257 <p><code>/configure [possible options]</code></p> 258 <p><code>make</code></p> 259 <p><code>make install</code></p> 260 <p>At that point you may have to rerun ldconfig or a similar utility to 261 update your list of installed shared libs.</p> 262 </li> 263 <li><em>What other libraries are needed to compile/install libxml2 ?</em> 264 <p>Libxml2 does not require any other library, the normal C ANSI API 265 should be sufficient (please report any violation to this rule you may 266 find).</p> 267 <p>However if found at configuration time libxml2 will detect and use the 268 following libs:</p> 269 <ul> 270 <li><a href="http://www.info-zip.org/pub/infozip/zlib/">libz</a> : a 271 highly portable and available widely compression library.</li> 272 <li>iconv: a powerful character encoding conversion library. It is 273 included by default in recent glibc libraries, so it doesn't need to 274 be installed specifically on Linux. It now seems a <a 275 href="http://www.opennc.org/onlinepubs/7908799/xsh/iconv.html">part 276 of the official UNIX</a> specification. Here is one <a 277 href="http://www.gnu.org/software/libiconv/">implementation of the 278 library</a> which source can be found <a 279 href="ftp://ftp.ilog.fr/pub/Users/haible/gnu/">here</a>.</li> 280 </ul> 281 </li> 282 <li><em>Make check fails on some platforms</em> 283 <p>Sometimes the regression tests' results don't completely match the 284 value produced by the parser, and the makefile uses diff to print the 285 delta. On some platforms the diff return breaks the compilation process; 286 if the diff is small this is probably not a serious problem.</p> 287 <p>Sometimes (especially on Solaris) make checks fail due to limitations 288 in make. Try using GNU-make instead.</p> 289 </li> 290 <li><em>I use the CVS version and there is no configure script</em> 291 <p>The configure script (and other Makefiles) are generated. Use the 292 autogen.sh script to regenerate the configure script and Makefiles, 293 like:</p> 294 <p><code>/autogen.sh --prefix=/usr --disable-shared</code></p> 295 </li> 296 <li><em>I have troubles when running make tests with gcc-3.0</em> 297 <p>It seems the initial release of gcc-3.0 has a problem with the 298 optimizer which miscompiles the URI module. Please use another 299 compiler.</p> 300 </li> 301</ol> 302 303<h3><a name="Developer">Developer</a> corner</h3> 304<ol> 305 <li><em>Troubles compiling or linking programs using libxml2</em> 306 <p>Usually the problem comes from the fact that the compiler doesn't get 307 the right compilation or linking flags. There is a small shell script 308 <code>xml2-config</code> which is installed as part of libxml2 usual 309 install process which provides those flags. Use</p> 310 <p><code>xml2-config --cflags</code></p> 311 <p>to get the compilation flags and</p> 312 <p><code>xml2-config --libs</code></p> 313 <p>to get the linker flags. Usually this is done directly from the 314 Makefile as:</p> 315 <p><code>CFLAGS=`xml2-config --cflags`</code></p> 316 <p><code>LIBS=`xml2-config --libs`</code></p> 317 </li> 318 <li><em>I want to install my own copy of libxml2 in my home directory and link 319 my programs against it, but it doesn't work</em> 320 <p>There are many different ways to accomplish this. Here is one way to 321 do this under Linux. Suppose your home directory is <code>/home/user. 322 </code>Then:</p> 323 <ul><li>Create a subdirectory, let's call it <code>myxml</code></li> 324 <li>unpack the libxml2 distribution into that subdirectory</li> 325 <li>chdir into the unpacked distribution (<code>/home/user/myxml/libxml2 326 </code>)</li> 327 <li>configure the library using the "<code>--prefix</code>" switch, 328 specifying an installation subdirectory in <code>/home/user/myxml</code>, 329 e.g. 330 <p><code>/configure --prefix /home/user/myxml/xmlinst</code> {other 331 configuration options}</p></li> 332 <li>now run <code>make</code> followed by <code>make install</code></li> 333 <li>At this point, the installation subdirectory contains the complete 334 "private" include files, library files and binary program files (e.g. 335 xmllint), located in 336 <p> <code>/home/user/myxml/xmlinst/lib, /home/user/myxml/xmlinst/include 337 </code> and <code> /home/user/myxml/xmlinst/bin</code></p> 338 respectively.</li> 339 <li>In order to use this "private" library, you should first add it 340 to the beginning of your default PATH (so that your own private 341 program files such as xmllint will be used instead of the normal 342 system ones). To do this, the Bash command would be 343 <p><code>export PATH=/home/user/myxml/xmlinst/bin:$PATH</code></p></li> 344 <li>Now suppose you have a program <code>test1.c</code> that you would 345 like to compile with your "private" library. Simply compile it 346 using the command <p><code>gcc `xml2-config --cflags --libs` -o test 347 test.c</code></p> Note that, because your PATH has been set with <code> 348 /home/user/myxml/xmlinst/bin</code> at the beginning, the 349 xml2-config program which you just installed will be used instead of 350 the system default one, and this will <em>automatically</em> get the 351 correct libraries linked with your program.</li></ul> 352 </li><p/> 353 <li><em>xmlDocDump() generates output on one line.</em> 354 <p>Libxml2 will not <strong>invent</strong> spaces in the content of a 355 document since <strong>all spaces in the content of a document are 356 significant</strong>. If you build a tree from the API and want 357 indentation:</p> 358 <ol> 359 <li>the correct way is to generate those yourself too.</li> 360 <li>the dangerous way is to ask libxml2 to add those blanks to your 361 content <strong>modifying the content of your document in the 362 process</strong>. The result may not be what you expect. There is 363 <strong>NO</strong> way to guarantee that such a modification won't 364 affect other parts of the content of your document. See <a 365 href="http://xmlsoft.org/html/libxml-parser.html#xmlKeepBlanksDefault">xmlKeepBlanksDefault 366 ()</a> and <a 367 href="http://xmlsoft.org/html/libxml-tree.html#xmlSaveFormatFile">xmlSaveFormatFile 368 ()</a></li> 369 </ol> 370 </li> 371 <li>Extra nodes in the document: 372 <p><em>For a XML file as below:</em></p> 373 <pre><?xml version="1.0"?> 374<PLAN xmlns="http://www.argus.ca/autotest/1.0/"> 375<NODE CommFlag="0"/> 376<NODE CommFlag="1"/> 377</PLAN></pre> 378 <p><em>after parsing it with the function 379 pxmlDoc=xmlParseFile(...);</em></p> 380 <p><em>I want to the get the content of the first node (node with the 381 CommFlag="0")</em></p> 382 <p><em>so I did it as following;</em></p> 383 <pre>xmlNodePtr pnode; 384pnode=pxmlDoc->children->children;</pre> 385 <p><em>but it does not work. If I change it to</em></p> 386 <pre>pnode=pxmlDoc->children->children->next;</pre> 387 <p><em>then it works. Can someone explain it to me.</em></p> 388 <p></p> 389 <p>In XML all characters in the content of the document are significant 390 <strong>including blanks and formatting line breaks</strong>.</p> 391 <p>The extra nodes you are wondering about are just that, text nodes with 392 the formatting spaces which are part of the document but that people tend 393 to forget. There is a function <a 394 href="http://xmlsoft.org/html/libxml-parser.html">xmlKeepBlanksDefault 395 ()</a> to remove those at parse time, but that's an heuristic, and its 396 use should be limited to cases where you are certain there is no 397 mixed-content in the document.</p> 398 </li> 399 <li><em>I get compilation errors of existing code like when accessing 400 <strong>root</strong> or <strong>child fields</strong> of nodes.</em> 401 <p>You are compiling code developed for libxml version 1 and using a 402 libxml2 development environment. Either switch back to libxml v1 devel or 403 even better fix the code to compile with libxml2 (or both) by <a 404 href="upgrade.html">following the instructions</a>.</p> 405 </li> 406 <li><em>I get compilation errors about non existing 407 <strong>xmlRootNode</strong> or <strong>xmlChildrenNode</strong> 408 fields.</em> 409 <p>The source code you are using has been <a 410 href="upgrade.html">upgraded</a> to be able to compile with both libxml 411 and libxml2, but you need to install a more recent version: 412 libxml(-devel) >= 1.8.8 or libxml2(-devel) >= 2.1.0</p> 413 </li> 414 <li><em>XPath implementation looks seriously broken</em> 415 <p>XPath implementation prior to 2.3.0 was really incomplete. Upgrade to 416 a recent version, there are no known bugs in the current version.</p> 417 </li> 418 <li><em>The example provided in the web page does not compile.</em> 419 <p>It's hard to maintain the documentation in sync with the code 420 <grin/> ...</p> 421 <p>Check the previous points 1/ and 2/ raised before, and please send 422 patches.</p> 423 </li> 424 <li><em>Where can I get more examples and information than provided on the 425 web page?</em> 426 <p>Ideally a libxml2 book would be nice. I have no such plan ... But you 427 can:</p> 428 <ul> 429 <li>check more deeply the <a href="html/libxml-lib.html">existing 430 generated doc</a></li> 431 <li>have a look at <a href="examples/index.html">the set of 432 examples</a>.</li> 433 <li>look for examples of use for libxml2 function using the Gnome code. 434 For example the following will query the full Gnome CVS base for the 435 use of the <strong>xmlAddChild()</strong> function: 436 <p><a 437 href="http://cvs.gnome.org/lxr/search?string=xmlAddChild">http://cvs.gnome.org/lxr/search?string=xmlAddChild</a></p> 438 <p>This may be slow, a large hardware donation to the gnome project 439 could cure this :-)</p> 440 </li> 441 <li><a 442 href="http://cvs.gnome.org/bonsai/rview.cgi?cvsroot=/cvs/gnome&dir=gnome-xml">Browse 443 the libxml2 source</a> , I try to write code as clean and documented 444 as possible, so looking at it may be helpful. In particular the code 445 of xmllint.c and of the various testXXX.c test programs should 446 provide good examples of how to do things with the library.</li> 447 </ul> 448 </li> 449 <li>What about C++ ? 450 <p>libxml2 is written in pure C in order to allow easy reuse on a number 451 of platforms, including embedded systems. I don't intend to convert to 452 C++.</p> 453 <p>There is however a C++ wrapper which may fulfill your needs:</p> 454 <ul> 455 <li>by Ari Johnson <ari@btigate.com>: 456 <p>Website: <a 457 href="http://libxmlplusplus.sourceforge.net/">http://libxmlplusplus.sourceforge.net/</a></p> 458 <p>Download: <a 459 href="http://sourceforge.net/project/showfiles.php?group_id=12999">http://sourceforge.net/project/showfiles.php?group_id=12999</a></p> 460 </li> 461 <!-- Website is currently unavailable as of 2003-08-02 462 <li>by Peter Jones <pjones@pmade.org> 463 <p>Website: <a 464 href="http://pmade.org/pjones/software/xmlwrapp/">http://pmade.org/pjones/software/xmlwrapp/</a></p> 465 </li> 466 --> 467 </ul> 468 </li> 469 <li>How to validate a document a posteriori ? 470 <p>It is possible to validate documents which had not been validated at 471 initial parsing time or documents which have been built from scratch 472 using the API. Use the <a 473 href="http://xmlsoft.org/html/libxml-valid.html#xmlValidateDtd">xmlValidateDtd()</a> 474 function. It is also possible to simply add a DTD to an existing 475 document:</p> 476 <pre>xmlDocPtr doc; /* your existing document */ 477xmlDtdPtr dtd = xmlParseDTD(NULL, filename_of_dtd); /* parse the DTD */ 478 479 dtd->name = xmlStrDup((xmlChar*)"root_name"); /* use the given root */ 480 481 doc->intSubset = dtd; 482 if (doc->children == NULL) xmlAddChild((xmlNodePtr)doc, (xmlNodePtr)dtd); 483 else xmlAddPrevSibling(doc->children, (xmlNodePtr)dtd); 484 </pre> 485 </li> 486 <li>So what is this funky "xmlChar" used all the time? 487 <p>It is a null terminated sequence of utf-8 characters. And only utf-8! 488 You need to convert strings encoded in different ways to utf-8 before 489 passing them to the API. This can be accomplished with the iconv library 490 for instance.</p> 491 </li> 492 <li>etc ...</li> 493</ol> 494 495<p></p> 496 497<h2><a name="Documentat">Developer Menu</a></h2> 498 499<p>There are several on-line resources related to using libxml:</p> 500<ol> 501 <li>Use the <a href="search.php">search engine</a> to look up 502 information.</li> 503 <li>Check the <a href="FAQ.html">FAQ.</a></li> 504 <li>Check the <a href="http://xmlsoft.org/html/libxml-lib.html">extensive 505 documentation</a> automatically extracted from code comments.</li> 506 <li>Look at the documentation about <a href="encoding.html">libxml 507 internationalization support</a>.</li> 508 <li>This page provides a global overview and <a href="example.html">some 509 examples</a> on how to use libxml.</li> 510 <li><a href="examples/index.html">Code examples</a></li> 511 <li>John Fleck's libxml2 tutorial: <a href="tutorial/index.html">html</a> 512 or <a href="tutorial/xmltutorial.pdf">pdf</a>.</li> 513 <li>If you need to parse large files, check the <a 514 href="xmlreader.html">xmlReader</a> API tutorial</li> 515 <li><a href="mailto:james@daa.com.au">James Henstridge</a> wrote <a 516 href="http://www.daa.com.au/~james/gnome/xml-sax/xml-sax.html">some nice 517 documentation</a> explaining how to use the libxml SAX interface.</li> 518 <li>George Lebl wrote <a 519 href="http://www-106.ibm.com/developerworks/library/l-gnome3/">an article 520 for IBM developerWorks</a> about using libxml.</li> 521 <li>Check <a href="http://cvs.gnome.org/lxr/source/gnome-xml/TODO">the TODO 522 file</a>.</li> 523 <li>Read the <a href="upgrade.html">1.x to 2.x upgrade path</a> 524 description. If you are starting a new project using libxml you should 525 really use the 2.x version.</li> 526 <li>And don't forget to look at the <a 527 href="http://mail.gnome.org/archives/xml/">mailing-list archive</a>.</li> 528</ol> 529 530<h2><a name="Reporting">Reporting bugs and getting help</a></h2> 531 532<p>Well, bugs or missing features are always possible, and I will make a 533point of fixing them in a timely fashion. The best way to report a bug is to 534use the <a href="http://bugzilla.gnome.org/buglist.cgi?product=libxml2">Gnome 535bug tracking database</a> (make sure to use the "libxml2" module name). I 536look at reports there regularly and it's good to have a reminder when a bug 537is still open. Be sure to specify that the bug is for the package libxml2.</p> 538 539<p>For small problems you can try to get help on IRC, the #xml channel on 540irc.gnome.org (port 6667) usually have a few person subscribed which may help 541(but there is no garantee and if a real issue is raised it should go on the 542mailing-list for archival).</p> 543 544<p>There is also a mailing-list <a 545href="mailto:xml@gnome.org">xml@gnome.org</a> for libxml, with an <a 546href="http://mail.gnome.org/archives/xml/">on-line archive</a> (<a 547href="http://xmlsoft.org/messages">old</a>). To subscribe to this list, 548please visit the <a 549href="http://mail.gnome.org/mailman/listinfo/xml">associated Web</a> page and 550follow the instructions. <strong>Do not send code, I won't debug it</strong> 551(but patches are really appreciated!).</p> 552 553<p>Please note that with the current amount of virus and SPAM, sending mail 554to the list without being subscribed won't work. There is *far too many 555bounces* (in the order of a thousand a day !) I cannot approve them manually 556anymore. If your mail to the list bounced waiting for administrator approval, 557it is LOST ! Repost it and fix the problem triggering the error.</p> 558 559<p>Check the following <strong><span style="color: #FF0000">before 560posting</span></strong>:</p> 561<ul> 562 <li>Read the <a href="FAQ.html">FAQ</a> and <a href="search.php">use the 563 search engine</a> to get information related to your problem.</li> 564 <li>Make sure you are <a href="ftp://xmlsoft.org/">using a recent 565 version</a>, and that the problem still shows up in a recent version.</li> 566 <li>Check the <a href="http://mail.gnome.org/archives/xml/">list 567 archives</a> to see if the problem was reported already. In this case 568 there is probably a fix available, similarly check the <a 569 href="http://bugzilla.gnome.org/buglist.cgi?product=libxml2">registered 570 open bugs</a>.</li> 571 <li>Make sure you can reproduce the bug with xmllint or one of the test 572 programs found in source in the distribution.</li> 573 <li>Please send the command showing the error as well as the input (as an 574 attachment)</li> 575</ul> 576 577<p>Then send the bug with associated information to reproduce it to the <a 578href="mailto:xml@gnome.org">xml@gnome.org</a> list; if it's really libxml 579related I will approve it. Please do not send mail to me directly, it makes 580things really hard to track and in some cases I am not the best person to 581answer a given question, ask on the list.</p> 582 583<p>To <span style="color: #E50000">be really clear about support</span>:</p> 584<ul> 585 <li>Support or help <span style="color: #E50000">requests MUST be sent to 586 the list or on bugzilla</span> in case of problems, so that the Question 587 and Answers can be shared publicly. Failing to do so carries the implicit 588 message "I want free support but I don't want to share the benefits with 589 others" and is not welcome. I will automatically Carbon-Copy the 590 xml@gnome.org mailing list for any technical reply made about libxml2 or 591 libxslt.</li> 592 <li>There is <span style="color: #E50000">no garantee of support</span>, if 593 your question remains unanswered after a week, repost it, making sure you 594 gave all the detail needed and the information requested.</li> 595 <li>Failing to provide information as requested or double checking first 596 for prior feedback also carries the implicit message "the time of the 597 library maintainers is less valuable than my time" and might not be 598 welcome.</li> 599</ul> 600 601<p>Of course, bugs reported with a suggested patch for fixing them will 602probably be processed faster than those without.</p> 603 604<p>If you're looking for help, a quick look at <a 605href="http://mail.gnome.org/archives/xml/">the list archive</a> may actually 606provide the answer. I usually send source samples when answering libxml2 607usage questions. The <a 608href="http://xmlsoft.org/html/book1.html">auto-generated documentation</a> is 609not as polished as I would like (i need to learn more about DocBook), but 610it's a good starting point.</p> 611 612<h2><a name="help">How to help</a></h2> 613 614<p>You can help the project in various ways, the best thing to do first is to 615subscribe to the mailing-list as explained before, check the <a 616href="http://mail.gnome.org/archives/xml/">archives </a>and the <a 617href="http://bugzilla.gnome.org/buglist.cgi?product=libxml2">Gnome bug 618database</a>:</p> 619<ol> 620 <li>Provide patches when you find problems.</li> 621 <li>Provide the diffs when you port libxml2 to a new platform. They may not 622 be integrated in all cases but help pinpointing portability problems 623 and</li> 624 <li>Provide documentation fixes (either as patches to the code comments or 625 as HTML diffs).</li> 626 <li>Provide new documentations pieces (translations, examples, etc 627 ...).</li> 628 <li>Check the TODO file and try to close one of the items.</li> 629 <li>Take one of the points raised in the archive or the bug database and 630 provide a fix. <a href="mailto:daniel@veillard.com">Get in touch with me 631 </a>before to avoid synchronization problems and check that the suggested 632 fix will fit in nicely :-)</li> 633</ol> 634 635<h2><a name="Downloads">Downloads</a></h2> 636 637<p>The latest versions of libxml2 can be found on the <a 638href="ftp://xmlsoft.org/">xmlsoft.org</a> server ( <a 639href="http://xmlsoft.org/sources/">HTTP</a>, <a 640href="ftp://xmlsoft.org/">FTP</a> and rsync are available), there is also 641mirrors (<a href="ftp://ftp.planetmirror.com/pub/xmlsoft/">Australia</a>( <a 642href="http://xmlsoft.planetmirror.com/">Web</a>), <a 643href="ftp://fr.rpmfind.net/pub/libxml/">France</a>) or on the <a 644href="ftp://ftp.gnome.org/pub/GNOME/MIRRORS.html">Gnome FTP server</a> as <a 645href="ftp://ftp.gnome.org/pub/GNOME/sources/libxml2/2.6/">source archive</a> 646, Antonin Sprinzl also provide <a href="ftp://gd.tuwien.ac.at/pub/libxml/">a 647mirror in Austria</a>. (NOTE that you need both the <a 648href="http://rpmfind.net/linux/RPM/libxml2.html">libxml(2)</a> and <a 649href="http://rpmfind.net/linux/RPM/libxml2-devel.html">libxml(2)-devel</a> 650packages installed to compile applications using libxml.)</p> 651 652<p>You can find all the history of libxml(2) and libxslt releases in the <a 653href="http://xmlsoft.org/sources/old/">old</a> directory. The precompiled 654Windows binaries made by Igor Zlatovic are available in the <a 655href="http://xmlsoft.org/sources/win32/">win32</a> directory.</p> 656 657<p>Binary ports:</p> 658<ul> 659 <li>Red Hat RPMs for i386 are available directly on <a 660 href="ftp://xmlsoft.org/">xmlsoft.org</a>, the source RPM will compile on 661 any architecture supported by Red Hat.</li> 662 <li><a href="mailto:igor@zlatkovic.com">Igor Zlatkovic</a> is now the 663 maintainer of the Windows port, <a 664 href="http://www.zlatkovic.com/projects/libxml/index.html">he provides 665 binaries</a>.</li> 666 <li>Blastwave provides 667 <a href="http://www.blastwave.org/packages.php/libxml2">Solaris binaries</a>.</li> 668 <li><a href="mailto:Steve.Ball@zveno.com">Steve Ball</a> provides <a 669 href="http://www.zveno.com/open_source/libxml2xslt.html">Mac Os X 670 binaries</a>.</li> 671 <li>The HP-UX porting center provides <a 672 href="http://hpux.connect.org.uk/hppd/hpux/Gnome/">HP-UX binaries</a></li> 673</ul> 674 675<p>If you know other supported binary ports, please <a 676href="http://veillard.com/">contact me</a>.</p> 677 678<p><a name="Snapshot">Snapshot:</a></p> 679<ul> 680 <li>Code from the W3C cvs base libxml2 module, updated hourly <a 681 href="ftp://xmlsoft.org/libxml2-cvs-snapshot.tar.gz">libxml2-cvs-snapshot.tar.gz</a>.</li> 682 <li>Docs, content of the web site, the list archive included <a 683 href="ftp://xmlsoft.org/libxml-docs.tar.gz">libxml-docs.tar.gz</a>.</li> 684</ul> 685 686<p><a name="Contribs">Contributions:</a></p> 687 688<p>I do accept external contributions, especially if compiling on another 689platform, get in touch with the list to upload the package, wrappers for 690various languages have been provided, and can be found in the <a 691href="python.html">bindings section</a></p> 692 693<p>Libxml2 is also available from CVS:</p> 694<ul> 695 <li><p>The <a href="http://cvs.gnome.org/viewcvs/libxml2/">Gnome CVS 696 base</a>. Check the <a 697 href="http://developer.gnome.org/tools/cvs.html">Gnome CVS Tools</a> 698 page; the CVS module is <b>libxml2</b>.</p> 699 </li> 700 <li>The <strong>libxslt</strong> module is also present there</li> 701</ul> 702 703<h2><a name="News">Releases</a></h2> 704 705<p>Items not finished and worked on, get in touch with the list if you want 706to help those</p> 707<ul> 708 <li>More testing on RelaxNG</li> 709 <li>Finishing up <a href="http://www.w3.org/TR/xmlschema-1/">XML 710 Schemas</a></li> 711</ul> 712 713<p>The <a href="ChangeLog.html">change log</a> describes the recents commits 714to the <a href="http://cvs.gnome.org/viewcvs/libxml2/">CVS</a> code base.</p> 715 716<p>There is the list of public releases:</p> 717 718<h3>2.6.16: Nov 10 2004</h3> 719<ul> 720 <li>general hardening and bug fixing crossing all the API based on new 721 automated regression testing</li> 722 <li>build fix: IPv6 build and test on AIX (Dodji Seketeli)</li> 723 <li>bug fixes: problem with XML::Libxml reported by Petr Pajas, encoding 724 conversion functions return values, UTF-8 bug affecting XPath reported by 725 Markus Bertheau, catalog problem with NULL entries (William Brack)</li> 726 <li>documentation: fix to xmllint man page, some API function descritpion 727 were updated.</li> 728 <li>improvements: DTD validation APIs provided at the Python level (Brent 729 Hendricks) </li> 730</ul> 731 732<h3>2.6.15: Oct 27 2004</h3> 733<ul> 734 <li>security fixes on the nanoftp and nanohttp modules</li> 735 <li>build fixes: xmllint detection bug in configure, building outside the 736 source tree (Thomas Fitzsimmons)</li> 737 <li>bug fixes: HTML parser on broken ASCII chars in names (William), Python 738 paths (Malcolm Tredinnick), xmlHasNsProp and default namespace (William), 739 saving to python file objects (Malcolm Tredinnick), DTD lookup fix 740 (Malcolm), save back <group> in catalogs (William), tree build 741 fixes (DV and Rob Richards), Schemas memory bug, structured error handler 742 on Python 64bits, thread local memory deallocation, memory leak reported 743 by Volker Roth, xmlValidateDtd in the presence of an internal subset, 744 entities and _private problem (William), xmlBuildRelativeURI error 745 (William).</li> 746 <li>improvements: better XInclude error reports (William), tree debugging 747 module and tests, convenience functions at the Reader API (Graham 748 Bennett), add support for PI in the HTML parser.</li> 749</ul> 750 751<h3>2.6.14: Sep 29 2004</h3> 752<ul> 753 <li>build fixes: configure paths for xmllint and xsltproc, compilation 754 without HTML parser, compilation warning cleanups (William Brack & 755 Malcolm Tredinnick), VMS makefile update (Craig Berry),</li> 756 <li>bug fixes: xmlGetUTF8Char (William Brack), QName properties (Kasimier 757 Buchcik), XInclude testing, Notation serialization, UTF8ToISO8859x 758 transcoding (Mark Itzcovitz), lots of XML Schemas cleanup and fixes 759 (Kasimier), ChangeLog cleanup (Stepan Kasal), memory fixes (Mark Vakoc), 760 handling of failed realloc(), out of bound array adressing in Schemas 761 date handling, Python space/tabs cleanups (Malcolm Tredinnick), NMTOKENS 762 E20 validation fix (Malcolm),</li> 763 <li>improvements: added W3C XML Schemas testsuite (Kasimier Buchcik), add 764 xmlSchemaValidateOneElement (Kasimier), Python exception hierearchy 765 (Malcolm Tredinnick), Python libxml2 driver improvement (Malcolm 766 Tredinnick), Schemas support for xsi:schemaLocation, 767 xsi:noNamespaceSchemaLocation, xsi:type (Kasimier Buchcik)</li> 768</ul> 769 770<h3>2.6.13: Aug 31 2004</h3> 771<ul> 772 <li>build fixes: Windows and zlib (Igor Zlatkovic), -O flag with gcc, 773 Solaris compiler warning, fixing RPM BuildRequires,</li> 774 <li>fixes: DTD loading on Windows (Igor), Schemas error reports APIs 775 (Kasimier Buchcik), Schemas validation crash, xmlCheckUTF8 (William Brack 776 and Julius Mittenzwei), Schemas facet check (Kasimier), default namespace 777 problem (William), Schemas hexbinary empty values, encoding error could 778 genrate a serialization loop.</li> 779 <li>Improvements: Schemas validity improvements (Kasimier), added --path 780 and --load-trace options to xmllint</li> 781 <li>documentation: tutorial update (John Fleck)</li> 782</ul> 783 784<h3>2.6.12: Aug 22 2004</h3> 785<ul> 786 <li>build fixes: fix --with-minimum, elfgcchack.h fixes (Peter 787 Breitenlohner), perl path lookup (William), diff on Solaris (Albert 788 Chin), some 64bits cleanups.</li> 789 <li>Python: avoid a warning with 2.3 (William Brack), tab and space mixes 790 (William), wrapper generator fixes (William), Cygwin support (Gerrit P. 791 Haase), node wrapper fix (Marc-Antoine Parent), XML Schemas support 792 (Torkel Lyng)</li> 793 <li>Schemas: a lot of bug fixes and improvements from Kasimier Buchcik</li> 794 <li>fixes: RVT fixes (William), XPath context resets bug (William), memory 795 debug (Steve Hay), catalog white space handling (Peter Breitenlohner), 796 xmlReader state after attribute reading (William), structured error 797 handler (William), XInclude generated xml:base fixup (William), Windows 798 memory reallocation problem (Steve Hay), Out of Memory conditions 799 handling (William and Olivier Andrieu), htmlNewDoc() charset bug, 800 htmlReadMemory init (William), a posteriori validation DTD base 801 (William), notations serialization missing, xmlGetNodePath (Dodji), 802 xmlCheckUTF8 (Diego Tartara), missing line numbers on entity 803 (William)</li> 804 <li>improvements: DocBook catalog build scrip (William), xmlcatalog tool 805 (Albert Chin), xmllint --c14n option, no_proxy environment (Mike Hommey), 806 xmlParseInNodeContext() addition, extend xmllint --shell, allow XInclude 807 to not generate start/end nodes, extend xmllint --version to include CVS 808 tag (William)</li> 809 <li>documentation: web pages fixes, validity API docs fixes (William) 810 schemas API fix (Eric Haszlakiewicz), xmllint man page (John Fleck)</li> 811</ul> 812 813<h3>2.6.11: July 5 2004</h3> 814<ul> 815 <li>Schemas: a lot of changes and improvements by Kasimier Buchcik for 816 attributes, namespaces and simple types.</li> 817 <li>build fixes: --with-minimum (William Brack), some gcc cleanup 818 (William), --with-thread-alloc (William)</li> 819 <li>portability: Windows binary package change (Igor Zlatkovic), Catalog 820 path on Windows</li> 821 <li>documentation: update to the tutorial (John Fleck), xmllint return code 822 (John Fleck), man pages (Ville Skytta),</li> 823 <li>bug fixes: C14N bug serializing namespaces (Aleksey Sanin), testSAX 824 properly initialize the library (William), empty node set in XPath 825 (William), xmlSchemas errors (William), invalid charref problem pointed 826 by Morus Walter, XInclude xml:base generation (William), Relax-NG bug 827 with div processing (William), XPointer and xml:base problem(William), 828 Reader and entities, xmllint return code for schemas (William), reader 829 streaming problem (Steve Ball), DTD serialization problem (William), 830 libxml.m4 fixes (Mike Hommey), do not provide destructors as methods on 831 Python classes, xmlReader buffer bug, Python bindings memory interfaces 832 improvement (with St�phane Bidoul), Fixed the push parser to be back to 833 synchronous behaviour.</li> 834 <li>improvement: custom per-thread I/O enhancement (Rob Richards), register 835 namespace in debug shell (Stefano Debenedetti), Python based regression 836 test for non-Unix users (William), dynamically increase the number of 837 XPath extension functions in Python and fix a memory leak (Marc-Antoine 838 Parent and William)</li> 839 <li>performance: hack done with Arjan van de Ven to reduce ELF footprint 840 and generated code on Linux, plus use gcc runtime profiling to optimize 841 the code generated in the RPM packages.</li> 842</ul> 843 844<h3>2.6.10: May 17 2004</h3> 845<ul> 846 <li>Web page generated for ChangeLog</li> 847 <li>build fixes: --without-html problems, make check without make all</li> 848 <li>portability: problem with xpath.c on Windows (MSC and Borland), memcmp 849 vs. strncmp on Solaris, XPath tests on Windows (Mark Vakoc), C++ do not 850 use "list" as parameter name, make tests work with Python 1.5 (Ed 851 Davis),</li> 852 <li>improvements: made xmlTextReaderMode public, small buffers resizing 853 (Morten Welinder), add --maxmem option to xmllint, add 854 xmlPopInputCallback() for Matt Sergeant, refactoring of serialization 855 escaping, added escaping customization</li> 856 <li>bugfixes: xsd:extension (Taihei Goi), assorted regexp bugs (William 857 Brack), xmlReader end of stream problem, node deregistration with reader, 858 URI escaping and filemanes, XHTML1 formatting (Nick Wellnhofer), regexp 859 transition reduction (William), various XSD Schemas fixes (Kasimier 860 Buchcik), XInclude fallback problem (William), weird problems with DTD 861 (William), structured error handler callback context (William), reverse 862 xmlEncodeSpecialChars() behaviour back to escaping '"'</li> 863</ul> 864 865<h3>2.6.9: Apr 18 2004</h3> 866<ul> 867 <li>implement xml:id Working Draft, relaxed XPath id() checking</li> 868 <li>bugfixes: xmlCtxtReset (Brent Hendricks), line number and CDATA (Dave 869 Beckett), Relax-NG compilation (William Brack), Regexp patches (with 870 William), xmlUriEscape (Mark Vakoc), a Relax-NG notAllowed problem (with 871 William), Relax-NG name classes compares (William), XInclude duplicate 872 fallback (William), external DTD encoding detection (William), a DTD 873 validation bug (William), xmlReader Close() fix, recusive extention 874 schemas</li> 875 <li>improvements: use xmlRead* APIs in test tools (Mark Vakoc), indenting 876 save optimization, better handle IIS broken HTTP redirect behaviour (Ian 877 Hummel), HTML parser frameset (James Bursa), libxml2-python RPM 878 dependancy, XML Schemas union support (Kasimier Buchcik), warning removal 879 clanup (William), keep ChangeLog compressed when installing from RPMs</li> 880 <li>documentation: examples and xmlDocDumpMemory docs (John Fleck), new 881 example (load, xpath, modify, save), xmlCatalogDump() comments,</li> 882 <li>Windows: Borland C++ builder (Eric Zurcher), work around Microsoft 883 compiler NaN handling bug (Mark Vakoc)</li> 884</ul> 885 886<h3>2.6.8: Mar 23 2004</h3> 887<ul> 888 <li>First step of the cleanup of the serialization code and APIs</li> 889 <li>XML Schemas: mixed content (Adam Dickmeiss), QName handling fixes (Adam 890 Dickmeiss), anyURI for "" (John Belmonte)</li> 891 <li>Python: Canonicalization C14N support added (Anthony Carrico)</li> 892 <li>xmlDocCopyNode() extension (William)</li> 893 <li>Relax-NG: fix when processing XInclude results (William), external 894 reference in interleave (William), missing error on <choice> 895 failure (William), memory leak in schemas datatype facets.</li> 896 <li>xmlWriter: patch for better DTD support (Alfred Mickautsch)</li> 897 <li>bug fixes: xmlXPathLangFunction memory leak (Mike Hommey and William 898 Brack), no ID errors if using HTML_PARSE_NOERROR, xmlcatalog fallbacks to 899 URI on SYSTEM lookup failure, XInclude parse flags inheritance (William), 900 XInclude and XPointer fixes for entities (William), XML parser bug 901 reported by Holger Rauch, nanohttp fd leak (William), regexps char 902 groups '-' handling (William), dictionnary reference counting problems, 903 do not close stderr.</li> 904 <li>performance patches from Petr Pajas</li> 905 <li>Documentation fixes: XML_CATALOG_FILES in man pages (Mike Hommey)</li> 906 <li>compilation and portability fixes: --without-valid, catalog cleanups 907 (Peter Breitenlohner), MingW patch (Roland Schwingel), cross-compilation 908 to Windows (Christophe de Vienne), --with-html-dir fixup (Julio Merino 909 Vidal), Windows build (Eric Zurcher)</li> 910</ul> 911 912<h3>2.6.7: Feb 23 2004</h3> 913<ul> 914 <li>documentation: tutorial updates (John Fleck), benchmark results</li> 915 <li>xmlWriter: updates and fixes (Alfred Mickautsch, Lucas Brasilino)</li> 916 <li>XPath optimization (Petr Pajas)</li> 917 <li>DTD ID handling optimization</li> 918 <li>bugfixes: xpath number with > 19 fractional (William Brack), push 919 mode with unescaped '>' characters, fix xmllint --stream --timing, fix 920 xmllint --memory --stream memory usage, xmlAttrSerializeTxtContent 921 handling NULL, trying to fix Relax-NG/Perl interface.</li> 922 <li>python: 2.3 compatibility, whitespace fixes (Malcolm Tredinnick)</li> 923 <li>Added relaxng option to xmllint --shell</li> 924</ul> 925 926<h3>2.6.6: Feb 12 2004</h3> 927<ul> 928 <li>nanohttp and nanoftp: buffer overflow error on URI parsing (Igor and 929 William) reported by Yuuichi Teranishi</li> 930 <li>bugfixes: make test and path issues, xmlWriter attribute serialization 931 (William Brack), xmlWriter indentation (William), schemas validation 932 (Eric Haszlakiewicz), XInclude dictionnaries issues (William and Oleg 933 Paraschenko), XInclude empty fallback (William), HTML warnings (William), 934 XPointer in XInclude (William), Python namespace serialization, 935 isolat1ToUTF8 bound error (Alfred Mickautsch), output of parameter 936 entities in internal subset (William), internal subset bug in push mode, 937 <xs:all> fix (Alexey Sarytchev)</li> 938 <li>Build: fix for automake-1.8 (Alexander Winston), warnings removal 939 (Philip Ludlam), SOCKLEN_T detection fixes (Daniel Richard), fix 940 --with-minimum configuration.</li> 941 <li>XInclude: allow the 2001 namespace without warning.</li> 942 <li>Documentation: missing example/index.html (John Fleck), version 943 dependancies (John Fleck)</li> 944 <li>reader API: structured error reporting (Steve Ball)</li> 945 <li>Windows compilation: mingw, msys (Mikhail Grushinskiy), function 946 prototype (Cameron Johnson), MSVC6 compiler warnings, _WINSOCKAPI_ 947 patch</li> 948 <li>Parsers: added xmlByteConsumed(ctxt) API to get the byte offest in 949 input.</li> 950</ul> 951 952<h3>2.6.5: Jan 25 2004</h3> 953<ul> 954 <li>Bugfixes: dictionnaries for schemas (William Brack), regexp segfault 955 (William), xs:all problem (William), a number of XPointer bugfixes 956 (William), xmllint error go to stderr, DTD validation problem with 957 namespace, memory leak (William), SAX1 cleanup and minimal options fixes 958 (Mark Vadoc), parser context reset on error (Shaun McCance), XPath union 959 evaluation problem (William) , xmlReallocLoc with NULL (Aleksey Sanin), 960 XML Schemas double free (Steve Ball), XInclude with no href, argument 961 callbacks order for XPath callbacks (Frederic Peters)</li> 962 <li>Documentation: python scripts (William Brack), xslt stylesheets (John 963 Fleck), doc (Sven Zimmerman), I/O example.</li> 964 <li>Python bindings: fixes (William), enum support (St�phane Bidoul), 965 structured error reporting (St�phane Bidoul)</li> 966 <li>XInclude: various fixes for conformance, problem related to dictionnary 967 references (William & me), recursion (William)</li> 968 <li>xmlWriter: indentation (Lucas Brasilino), memory leaks (Alfred 969 Mickautsch),</li> 970 <li>xmlSchemas: normalizedString datatype (John Belmonte)</li> 971 <li>code cleanup for strings functions (William)</li> 972 <li>Windows: compiler patches (Mark Vakoc)</li> 973 <li>Parser optimizations, a few new XPath and dictionnary APIs for future 974 XSLT optimizations.</li> 975</ul> 976 977<h3>2.6.4: Dec 24 2003</h3> 978<ul> 979 <li>Windows build fixes (Igor Zlatkovic)</li> 980 <li>Some serious XInclude problems reported by Oleg Paraschenko and</li> 981 <li>Unix and Makefile packaging fixes (me, William Brack,</li> 982 <li>Documentation improvements (John Fleck, William Brack), example fix 983 (Lucas Brasilino)</li> 984 <li>bugfixes: xmlTextReaderExpand() with xmlReaderWalker, XPath handling of 985 NULL strings (William Brack) , API building reader or parser from 986 filedescriptor should not close it, changed XPath sorting to be stable 987 again (William Brack), xmlGetNodePath() generating '(null)' (William 988 Brack), DTD validation and namespace bug (William Brack), XML Schemas 989 double inclusion behaviour</li> 990</ul> 991 992<h3>2.6.3: Dec 10 2003</h3> 993<ul> 994 <li>documentation updates and cleanup (DV, William Brack, John Fleck)</li> 995 <li>added a repository of examples, examples from Aleksey Sanin, Dodji 996 Seketeli, Alfred Mickautsch</li> 997 <li>Windows updates: Mark Vakoc, Igor Zlatkovic, Eric Zurcher, Mingw 998 (Kenneth Haley)</li> 999 <li>Unicode range checking (William Brack)</li> 1000 <li>code cleanup (William Brack)</li> 1001 <li>Python bindings: doc (John Fleck), bug fixes</li> 1002 <li>UTF-16 cleanup and BOM issues (William Brack)</li> 1003 <li>bug fixes: ID and xmlReader validation, XPath (William Brack), 1004 xmlWriter (Alfred Mickautsch), hash.h inclusion problem, HTML parser 1005 (James Bursa), attribute defaulting and validation, some serialization 1006 cleanups, XML_GET_LINE macro, memory debug when using threads (William 1007 Brack), serialization of attributes and entities content, xmlWriter 1008 (Daniel Schulman)</li> 1009 <li>XInclude bugfix, new APIs and update to the last version including the 1010 namespace change.</li> 1011 <li>XML Schemas improvements: include (Robert Stepanek), import and 1012 namespace handling, fixed the regression tests troubles, added examples 1013 based on Eric van der Vlist book, regexp fixes</li> 1014 <li>preliminary pattern support for streaming (needed for schemas 1015 constraints), added xmlTextReaderPreservePattern() to collect subdocument 1016 when streaming.</li> 1017 <li>various fixes in the structured error handling</li> 1018</ul> 1019 1020<h3>2.6.2: Nov 4 2003</h3> 1021<ul> 1022 <li>XPath context unregistration fixes</li> 1023 <li>text node coalescing fixes (Mark Lilback)</li> 1024 <li>API to screate a W3C Schemas from an existing document (Steve Ball)</li> 1025 <li>BeOS patches (Marcin 'Shard' Konicki)</li> 1026 <li>xmlStrVPrintf function added (Aleksey Sanin)</li> 1027 <li>compilation fixes (Mark Vakoc)</li> 1028 <li>stdin parsing fix (William Brack)</li> 1029 <li>a posteriori DTD validation fixes</li> 1030 <li>xmlReader bug fixes: Walker fixes, python bindings</li> 1031 <li>fixed xmlStopParser() to really stop the parser and errors</li> 1032 <li>always generate line numbers when using the new xmlReadxxx 1033 functions</li> 1034 <li>added XInclude support to the xmlReader interface</li> 1035 <li>implemented XML_PARSE_NONET parser option</li> 1036 <li>DocBook XSLT processing bug fixed</li> 1037 <li>HTML serialization for <p> elements (William Brack and me)</li> 1038 <li>XPointer failure in XInclude are now handled as resource errors</li> 1039 <li>fixed xmllint --html to use the HTML serializer on output (added 1040 --xmlout to implement the previous behaviour of saving it using the XML 1041 serializer)</li> 1042</ul> 1043 1044<h3>2.6.1: Oct 28 2003</h3> 1045<ul> 1046 <li>Mostly bugfixes after the big 2.6.0 changes</li> 1047 <li>Unix compilation patches: libxml.m4 (Patrick Welche), warnings cleanup 1048 (William Brack)</li> 1049 <li>Windows compilation patches (Joachim Bauch, Stephane Bidoul, Igor 1050 Zlatkovic)</li> 1051 <li>xmlWriter bugfix (Alfred Mickautsch)</li> 1052 <li>chvalid.[ch]: couple of fixes from Stephane Bidoul</li> 1053 <li>context reset: error state reset, push parser reset (Graham 1054 Bennett)</li> 1055 <li>context reuse: generate errors if file is not readable</li> 1056 <li>defaulted attributes for element coming from internal entities 1057 (Stephane Bidoul)</li> 1058 <li>Python: tab and spaces mix (William Brack)</li> 1059 <li>Error handler could crash in DTD validation in 2.6.0</li> 1060 <li>xmlReader: do not use the document or element _private field</li> 1061 <li>testSAX.c: avoid a problem with some PIs (Massimo Morara)</li> 1062 <li>general bug fixes: mandatory encoding in text decl, serializing 1063 Document Fragment nodes, xmlSearchNs 2.6.0 problem (Kasimier Buchcik), 1064 XPath errors not reported, slow HTML parsing of large documents.</li> 1065</ul> 1066 1067<h3>2.6.0: Oct 20 2003</h3> 1068<ul> 1069 <li>Major revision release: should be API and ABI compatible but got a lot 1070 of change</li> 1071 <li>Increased the library modularity, far more options can be stripped out, 1072 a --with-minimum configuration will weight around 160KBytes</li> 1073 <li>Use per parser and per document dictionnary, allocate names and small 1074 text nodes from the dictionnary</li> 1075 <li>Switch to a SAX2 like parser rewrote most of the XML parser core, 1076 provides namespace resolution and defaulted attributes, minimize memory 1077 allocations and copies, namespace checking and specific error handling, 1078 immutable buffers, make predefined entities static structures, etc...</li> 1079 <li>rewrote all the error handling in the library, all errors can be 1080 intercepted at a structured level, with precise information 1081 available.</li> 1082 <li>New simpler and more generic XML and HTML parser APIs, allowing to 1083 easilly modify the parsing options and reuse parser context for multiple 1084 consecutive documents.</li> 1085 <li>Similar new APIs for the xmlReader, for options and reuse, provided new 1086 functions to access content as const strings, use them for Python 1087 bindings</li> 1088 <li>a lot of other smaller API improvements: xmlStrPrintf (Aleksey Sanin), 1089 Walker i.e. reader on a document tree based on Alfred Mickautsch code, 1090 make room in nodes for line numbers, reference counting and future PSVI 1091 extensions, generation of character ranges to be checked with faster 1092 algorithm (William), xmlParserMaxDepth (Crutcher Dunnavant), buffer 1093 access</li> 1094 <li>New xmlWriter API provided by Alfred Mickautsch</li> 1095 <li>Schemas: base64 support by Anthony Carrico</li> 1096 <li>Parser<->HTTP integration fix, proper processing of the Mime-Type 1097 and charset informations if available.</li> 1098 <li>Relax-NG: bug fixes including the one reported by Martijn Faassen and 1099 zeroOrMore, better error reporting.</li> 1100 <li>Python bindings (St�phane Bidoul), never use stdout for errors 1101 output</li> 1102 <li>Portability: all the headers have macros for export and calling 1103 convention definitions (Igor Zlatkovic), VMS update (Craig A. Berry), 1104 Windows: threads (Jesse Pelton), Borland compiler (Eric Zurcher, Igor), 1105 Mingw (Igor), typos (Mark Vakoc), beta version (Stephane Bidoul), 1106 warning cleanups on AIX and MIPS compilers (William Brack), BeOS (Marcin 1107 'Shard' Konicki)</li> 1108 <li>Documentation fixes and README (William Brack), search fix (William), 1109 tutorial updates (John Fleck), namespace docs (Stefan Kost)</li> 1110 <li>Bug fixes: xmlCleanupParser (Dave Beckett), threading uninitialized 1111 mutexes, HTML doctype lowercase, SAX/IO (William), compression detection 1112 and restore (William), attribute declaration in DTDs (William), namespace 1113 on attribute in HTML output (William), input filename (Rob Richards), 1114 namespace DTD validation, xmlReplaceNode (Chris Ryland), I/O callbacks 1115 (Markus Keim), CDATA serialization (Shaun McCance), xmlReader (Peter 1116 Derr), high codepoint charref like &#x10FFFF;, buffer access in push 1117 mode (Justin Fletcher), TLS threads on Windows (Jesse Pelton), XPath bug 1118 (William), xmlCleanupParser (Marc Liyanage), CDATA output (William), HTTP 1119 error handling.</li> 1120 <li>xmllint options: --dtdvalidfpi for Tobias Reif, --sax1 for compat 1121 testing, --nodict for building without tree dictionnary, --nocdata to 1122 replace CDATA by text, --nsclean to remove surperfluous namespace 1123 declarations</li> 1124 <li>added xml2-config --libtool-libs option from Kevin P. Fleming</li> 1125 <li>a lot of profiling and tuning of the code, speedup patch for 1126 xmlSearchNs() by Luca Padovani. The xmlReader should do far less 1127 allocation and it speed should get closer to SAX. Chris Anderson worked 1128 on speeding and cleaning up repetitive checking code.</li> 1129 <li>cleanup of "make tests"</li> 1130 <li>libxml-2.0-uninstalled.pc from Malcolm Tredinnick</li> 1131 <li>deactivated the broken docBook SGML parser code and plugged the XML 1132 parser instead.</li> 1133</ul> 1134 1135<h3>2.5.11: Sep 9 2003</h3> 1136 1137<p>A bugfix only release:</p> 1138<ul> 1139 <li>risk of crash in Relax-NG</li> 1140 <li>risk of crash when using multithreaded programs</li> 1141</ul> 1142 1143<h3>2.5.10: Aug 15 2003</h3> 1144 1145<p>A bugfixes only release</p> 1146<ul> 1147 <li>Windows Makefiles (William Brack)</li> 1148 <li>UTF-16 support fixes (Mark Itzcovitz)</li> 1149 <li>Makefile and portability (William Brack) automake, Linux alpha, Mingw 1150 on Windows (Mikhail Grushinskiy)</li> 1151 <li>HTML parser (Oliver Stoeneberg)</li> 1152 <li>XInclude performance problem reported by Kevin Ruscoe</li> 1153 <li>XML parser performance problem reported by Grant Goodale</li> 1154 <li>xmlSAXParseDTD() bug fix from Malcolm Tredinnick</li> 1155 <li>and a couple other cleanup</li> 1156</ul> 1157 1158<h3>2.5.9: Aug 9 2003</h3> 1159<ul> 1160 <li>bugfixes: IPv6 portability, xmlHasNsProp (Markus Keim), Windows build 1161 (Wiliam Brake, Jesse Pelton, Igor), Schemas (Peter Sobisch), threading 1162 (Rob Richards), hexBinary type (), UTF-16 BOM (Dodji Seketeli), 1163 xmlReader, Relax-NG schemas compilation, namespace handling, EXSLT (Sean 1164 Griffin), HTML parsing problem (William Brack), DTD validation for mixed 1165 content + namespaces, HTML serialization, library initialization, 1166 progressive HTML parser</li> 1167 <li>better interfaces for Relax-NG error handling (Joachim Bauch, )</li> 1168 <li>adding xmlXIncludeProcessTree() for XInclud'ing in a subtree</li> 1169 <li>doc fixes and improvements (John Fleck)</li> 1170 <li>configure flag for -with-fexceptions when embedding in C++</li> 1171 <li>couple of new UTF-8 helper functions (William Brack)</li> 1172 <li>general encoding cleanup + ISO-8859-x without iconv (Peter Jacobi)</li> 1173 <li>xmlTextReader cleanup + enum for node types (Bjorn Reese)</li> 1174 <li>general compilation/warning cleanup Solaris/HP-UX/... (William 1175 Brack)</li> 1176</ul> 1177 1178<h3>2.5.8: Jul 6 2003</h3> 1179<ul> 1180 <li>bugfixes: XPath, XInclude, file/URI mapping, UTF-16 save (Mark 1181 Itzcovitz), UTF-8 checking, URI saving, error printing (William Brack), 1182 PI related memleak, compilation without schemas or without xpath (Joerg 1183 Schmitz-Linneweber/Garry Pennington), xmlUnlinkNode problem with DTDs, 1184 rpm problem on , i86_64, removed a few compilation problems from 2.5.7, 1185 xmlIOParseDTD, and xmlSAXParseDTD (Malcolm Tredinnick)</li> 1186 <li>portability: DJGPP (MsDos) , OpenVMS (Craig A. Berry)</li> 1187 <li>William Brack fixed multithreading lock problems</li> 1188 <li>IPv6 patch for FTP and HTTP accesses (Archana Shah/Wipro)</li> 1189 <li>Windows fixes (Igor Zlatkovic, Eric Zurcher), threading (St�phane 1190 Bidoul)</li> 1191 <li>A few W3C Schemas Structure improvements</li> 1192 <li>W3C Schemas Datatype improvements (Charlie Bozeman)</li> 1193 <li>Python bindings for thread globals (St�phane Bidoul), and method/class 1194 generator</li> 1195 <li>added --nonet option to xmllint</li> 1196 <li>documentation improvements (John Fleck)</li> 1197</ul> 1198 1199<h3>2.5.7: Apr 25 2003</h3> 1200<ul> 1201 <li>Relax-NG: Compiling to regexp and streaming validation on top of the 1202 xmlReader interface, added to xmllint --stream</li> 1203 <li>xmlReader: Expand(), Next() and DOM access glue, bug fixes</li> 1204 <li>Support for large files: RGN validated a 4.5GB instance</li> 1205 <li>Thread support is now configured in by default</li> 1206 <li>Fixes: update of the Trio code (Bjorn), WXS Date and Duration fixes 1207 (Charles Bozeman), DTD and namespaces (Brent Hendricks), HTML push parser 1208 and zero bytes handling, some missing Windows file path conversions, 1209 behaviour of the parser and validator in the presence of "out of memory" 1210 error conditions</li> 1211 <li>extended the API to be able to plug a garbage collecting memory 1212 allocator, added xmlMallocAtomic() and modified the allocations 1213 accordingly.</li> 1214 <li>Performances: removed excessive malloc() calls, speedup of the push and 1215 xmlReader interfaces, removed excessive thread locking</li> 1216 <li>Documentation: man page (John Fleck), xmlReader documentation</li> 1217 <li>Python: adding binding for xmlCatalogAddLocal (Brent M Hendricks)</li> 1218</ul> 1219 1220<h3>2.5.6: Apr 1 2003</h3> 1221<ul> 1222 <li>Fixed W3C XML Schemas datatype, should be compliant now except for 1223 binHex and base64 which are not supported yet.</li> 1224 <li>bug fixes: non-ASCII IDs, HTML output, XInclude on large docs and 1225 XInclude entities handling, encoding detection on external subsets, XML 1226 Schemas bugs and memory leaks, HTML parser (James Bursa)</li> 1227 <li>portability: python/trio (Albert Chin), Sun compiler warnings</li> 1228 <li>documentation: added --relaxng option to xmllint man page (John)</li> 1229 <li>improved error reporting: xml:space, start/end tag mismatches, Relax NG 1230 errors</li> 1231</ul> 1232 1233<h3>2.5.5: Mar 24 2003</h3> 1234<ul> 1235 <li>Lot of fixes on the Relax NG implementation. More testing including 1236 DocBook and TEI examples.</li> 1237 <li>Increased the support for W3C XML Schemas datatype</li> 1238 <li>Several bug fixes in the URI handling layer</li> 1239 <li>Bug fixes: HTML parser, xmlReader, DTD validation, XPath, encoding 1240 conversion, line counting in the parser.</li> 1241 <li>Added support for $XMLLINT_INDENT environment variable, FTP delete</li> 1242 <li>Fixed the RPM spec file name</li> 1243</ul> 1244 1245<h3>2.5.4: Feb 20 2003</h3> 1246<ul> 1247 <li>Conformance testing and lot of fixes on Relax NG and XInclude 1248 implementation</li> 1249 <li>Implementation of XPointer element() scheme</li> 1250 <li>Bug fixes: XML parser, XInclude entities merge, validity checking on 1251 namespaces, 1252 <p>2 serialization bugs, node info generation problems, a DTD regexp 1253 generation problem.</p> 1254 </li> 1255 <li>Portability: windows updates and path canonicalization (Igor)</li> 1256 <li>A few typo fixes (Kjartan Maraas)</li> 1257 <li>Python bindings generator fixes (Stephane Bidoul)</li> 1258</ul> 1259 1260<h3>2.5.3: Feb 10 2003</h3> 1261<ul> 1262 <li>RelaxNG and XML Schemas datatypes improvements, and added a first 1263 version of RelaxNG Python bindings</li> 1264 <li>Fixes: XLink (Sean Chittenden), XInclude (Sean Chittenden), API fix for 1265 serializing namespace nodes, encoding conversion bug, XHTML1 1266 serialization</li> 1267 <li>Portability fixes: Windows (Igor), AMD 64bits RPM spec file</li> 1268</ul> 1269 1270<h3>2.5.2: Feb 5 2003</h3> 1271<ul> 1272 <li>First implementation of RelaxNG, added --relaxng flag to xmllint</li> 1273 <li>Schemas support now compiled in by default.</li> 1274 <li>Bug fixes: DTD validation, namespace checking, XInclude and entities, 1275 delegateURI in XML Catalogs, HTML parser, XML reader (St�phane Bidoul), 1276 XPath parser and evaluation, UTF8ToUTF8 serialization, XML reader memory 1277 consumption, HTML parser, HTML serialization in the presence of 1278 namespaces</li> 1279 <li>added an HTML API to check elements and attributes.</li> 1280 <li>Documentation improvement, PDF for the tutorial (John Fleck), doc 1281 patches (Stefan Kost)</li> 1282 <li>Portability fixes: NetBSD (Julio Merino), Windows (Igor Zlatkovic)</li> 1283 <li>Added python bindings for XPointer, contextual error reporting 1284 (St�phane Bidoul)</li> 1285 <li>URI/file escaping problems (Stefano Zacchiroli)</li> 1286</ul> 1287 1288<h3>2.5.1: Jan 8 2003</h3> 1289<ul> 1290 <li>Fixes a memory leak and configuration/compilation problems in 2.5.0</li> 1291 <li>documentation updates (John)</li> 1292 <li>a couple of XmlTextReader fixes</li> 1293</ul> 1294 1295<h3>2.5.0: Jan 6 2003</h3> 1296<ul> 1297 <li>New <a href="xmlreader.html">XmltextReader interface</a> based on C# 1298 API (with help of St�phane Bidoul)</li> 1299 <li>Windows: more exports, including the new API (Igor)</li> 1300 <li>XInclude fallback fix</li> 1301 <li>Python: bindings for the new API, packaging (St�phane Bidoul), 1302 drv_libxml2.py Python xml.sax driver (St�phane Bidoul), fixes, speedup 1303 and iterators for Python-2.2 (Hannu Krosing)</li> 1304 <li>Tutorial fixes (john Fleck and Niraj Tolia) xmllint man update 1305 (John)</li> 1306 <li>Fix an XML parser bug raised by Vyacheslav Pindyura</li> 1307 <li>Fix for VMS serialization (Nigel Hall) and config (Craig A. Berry)</li> 1308 <li>Entities handling fixes</li> 1309 <li>new API to optionally track node creation and deletion (Lukas 1310 Schroeder)</li> 1311 <li>Added documentation for the XmltextReader interface and some <a 1312 href="guidelines.html">XML guidelines</a></li> 1313</ul> 1314 1315<h3>2.4.30: Dec 12 2002</h3> 1316<ul> 1317 <li>2.4.29 broke the python bindings, rereleasing</li> 1318 <li>Improvement/fixes of the XML API generator, and couple of minor code 1319 fixes.</li> 1320</ul> 1321 1322<h3>2.4.29: Dec 11 2002</h3> 1323<ul> 1324 <li>Windows fixes (Igor): Windows CE port, pthread linking, python bindings 1325 (St�phane Bidoul), Mingw (Magnus Henoch), and export list updates</li> 1326 <li>Fix for prev in python bindings (ERDI Gergo)</li> 1327 <li>Fix for entities handling (Marcus Clarke)</li> 1328 <li>Refactored the XML and HTML dumps to a single code path, fixed XHTML1 1329 dump</li> 1330 <li>Fix for URI parsing when handling URNs with fragment identifiers</li> 1331 <li>Fix for HTTP URL escaping problem</li> 1332 <li>added an TextXmlReader (C#) like API (work in progress)</li> 1333 <li>Rewrote the API in XML generation script, includes a C parser and saves 1334 more informations needed for C# bindings</li> 1335</ul> 1336 1337<h3>2.4.28: Nov 22 2002</h3> 1338<ul> 1339 <li>a couple of python binding fixes</li> 1340 <li>2 bug fixes in the XML push parser</li> 1341 <li>potential memory leak removed (Martin Stoilov)</li> 1342 <li>fix to the configure script for Unix (Dimitri Papadopoulos)</li> 1343 <li>added encoding support for XInclude parse="text"</li> 1344 <li>autodetection of XHTML1 and specific serialization rules added</li> 1345 <li>nasty threading bug fixed (William Brack)</li> 1346</ul> 1347 1348<h3>2.4.27: Nov 17 2002</h3> 1349<ul> 1350 <li>fixes for the Python bindings</li> 1351 <li>a number of bug fixes: SGML catalogs, xmlParseBalancedChunkMemory(), 1352 HTML parser, Schemas (Charles Bozeman), document fragment support 1353 (Christian Glahn), xmlReconciliateNs (Brian Stafford), XPointer, 1354 xmlFreeNode(), xmlSAXParseMemory (Peter Jones), xmlGetNodePath (Petr 1355 Pajas), entities processing</li> 1356 <li>added grep to xmllint --shell</li> 1357 <li>VMS update patch from Craig A. Berry</li> 1358 <li>cleanup of the Windows build with support for more compilers (Igor), 1359 better thread support on Windows</li> 1360 <li>cleanup of Unix Makefiles and spec file</li> 1361 <li>Improvements to the documentation (John Fleck)</li> 1362</ul> 1363 1364<h3>2.4.26: Oct 18 2002</h3> 1365<ul> 1366 <li>Patches for Windows CE port, improvements on Windows paths handling</li> 1367 <li>Fixes to the validation code (DTD and Schemas), xmlNodeGetPath() , 1368 HTML serialization, Namespace compliance, and a number of small 1369 problems</li> 1370</ul> 1371 1372<h3>2.4.25: Sep 26 2002</h3> 1373<ul> 1374 <li>A number of bug fixes: XPath, validation, Python bindings, DOM and 1375 tree, xmlI/O, Html</li> 1376 <li>Serious rewrite of XInclude</li> 1377 <li>Made XML Schemas regexp part of the default build and APIs, small fix 1378 and improvement of the regexp core</li> 1379 <li>Changed the validation code to reuse XML Schemas regexp APIs</li> 1380 <li>Better handling of Windows file paths, improvement of Makefiles (Igor, 1381 Daniel Gehriger, Mark Vakoc)</li> 1382 <li>Improved the python I/O bindings, the tests, added resolver and regexp 1383 APIs</li> 1384 <li>New logos from Marc Liyanage</li> 1385 <li>Tutorial improvements: John Fleck, Christopher Harris</li> 1386 <li>Makefile: Fixes for AMD x86_64 (Mandrake), DESTDIR (Christophe 1387 Merlet)</li> 1388 <li>removal of all stderr/perror use for error reporting</li> 1389 <li>Better error reporting: XPath and DTD validation</li> 1390 <li>update of the trio portability layer (Bjorn Reese)</li> 1391</ul> 1392 1393<p><strong>2.4.24: Aug 22 2002</strong></p> 1394<ul> 1395 <li>XPath fixes (William), xf:escape-uri() (Wesley Terpstra)</li> 1396 <li>Python binding fixes: makefiles (William), generator, rpm build, x86-64 1397 (fcrozat)</li> 1398 <li>HTML <style> and boolean attributes serializer fixes</li> 1399 <li>C14N improvements by Aleksey</li> 1400 <li>doc cleanups: Rick Jones</li> 1401 <li>Windows compiler makefile updates: Igor and Elizabeth Barham</li> 1402 <li>XInclude: implementation of fallback and xml:base fixup added</li> 1403</ul> 1404 1405<h3>2.4.23: July 6 2002</h3> 1406<ul> 1407 <li>performances patches: Peter Jacobi</li> 1408 <li>c14n fixes, testsuite and performances: Aleksey Sanin</li> 1409 <li>added xmlDocFormatDump: Chema Celorio</li> 1410 <li>new tutorial: John Fleck</li> 1411 <li>new hash functions and performances: Sander Vesik, portability fix from 1412 Peter Jacobi</li> 1413 <li>a number of bug fixes: XPath (William Brack, Richard Jinks), XML and 1414 HTML parsers, ID lookup function</li> 1415 <li>removal of all remaining sprintf: Aleksey Sanin</li> 1416</ul> 1417 1418<h3>2.4.22: May 27 2002</h3> 1419<ul> 1420 <li>a number of bug fixes: configure scripts, base handling, parser, memory 1421 usage, HTML parser, XPath, documentation (Christian Cornelssen), 1422 indentation, URI parsing</li> 1423 <li>Optimizations for XMLSec, fixing and making public some of the network 1424 protocol handlers (Aleksey)</li> 1425 <li>performance patch from Gary Pennington</li> 1426 <li>Charles Bozeman provided date and time support for XML Schemas 1427 datatypes</li> 1428</ul> 1429 1430<h3>2.4.21: Apr 29 2002</h3> 1431 1432<p>This release is both a bug fix release and also contains the early XML 1433Schemas <a href="http://www.w3.org/TR/xmlschema-1/">structures</a> and <a 1434href="http://www.w3.org/TR/xmlschema-2/">datatypes</a> code, beware, all 1435interfaces are likely to change, there is huge holes, it is clearly a work in 1436progress and don't even think of putting this code in a production system, 1437it's actually not compiled in by default. The real fixes are:</p> 1438<ul> 1439 <li>a couple of bugs or limitations introduced in 2.4.20</li> 1440 <li>patches for Borland C++ and MSC by Igor</li> 1441 <li>some fixes on XPath strings and conformance patches by Richard 1442 Jinks</li> 1443 <li>patch from Aleksey for the ExcC14N specification</li> 1444 <li>OSF/1 bug fix by Bjorn</li> 1445</ul> 1446 1447<h3>2.4.20: Apr 15 2002</h3> 1448<ul> 1449 <li>bug fixes: file descriptor leak, XPath, HTML output, DTD validation</li> 1450 <li>XPath conformance testing by Richard Jinks</li> 1451 <li>Portability fixes: Solaris, MPE/iX, Windows, OSF/1, python bindings, 1452 libxml.m4</li> 1453</ul> 1454 1455<h3>2.4.19: Mar 25 2002</h3> 1456<ul> 1457 <li>bug fixes: half a dozen XPath bugs, Validation, ISO-Latin to UTF8 1458 encoder</li> 1459 <li>portability fixes in the HTTP code</li> 1460 <li>memory allocation checks using valgrind, and profiling tests</li> 1461 <li>revamp of the Windows build and Makefiles</li> 1462</ul> 1463 1464<h3>2.4.18: Mar 18 2002</h3> 1465<ul> 1466 <li>bug fixes: tree, SAX, canonicalization, validation, portability, 1467 XPath</li> 1468 <li>removed the --with-buffer option it was becoming unmaintainable</li> 1469 <li>serious cleanup of the Python makefiles</li> 1470 <li>speedup patch to XPath very effective for DocBook stylesheets</li> 1471 <li>Fixes for Windows build, cleanup of the documentation</li> 1472</ul> 1473 1474<h3>2.4.17: Mar 8 2002</h3> 1475<ul> 1476 <li>a lot of bug fixes, including "namespace nodes have no parents in 1477 XPath"</li> 1478 <li>fixed/improved the Python wrappers, added more examples and more 1479 regression tests, XPath extension functions can now return node-sets</li> 1480 <li>added the XML Canonicalization support from Aleksey Sanin</li> 1481</ul> 1482 1483<h3>2.4.16: Feb 20 2002</h3> 1484<ul> 1485 <li>a lot of bug fixes, most of them were triggered by the XML Testsuite 1486 from OASIS and W3C. Compliance has been significantly improved.</li> 1487 <li>a couple of portability fixes too.</li> 1488</ul> 1489 1490<h3>2.4.15: Feb 11 2002</h3> 1491<ul> 1492 <li>Fixed the Makefiles, especially the python module ones</li> 1493 <li>A few bug fixes and cleanup</li> 1494 <li>Includes cleanup</li> 1495</ul> 1496 1497<h3>2.4.14: Feb 8 2002</h3> 1498<ul> 1499 <li>Change of License to the <a 1500 href="http://www.opensource.org/licenses/mit-license.html">MIT 1501 License</a> basically for integration in XFree86 codebase, and removing 1502 confusion around the previous dual-licensing</li> 1503 <li>added Python bindings, beta software but should already be quite 1504 complete</li> 1505 <li>a large number of fixes and cleanups, especially for all tree 1506 manipulations</li> 1507 <li>cleanup of the headers, generation of a reference API definition in 1508 XML</li> 1509</ul> 1510 1511<h3>2.4.13: Jan 14 2002</h3> 1512<ul> 1513 <li>update of the documentation: John Fleck and Charlie Bozeman</li> 1514 <li>cleanup of timing code from Justin Fletcher</li> 1515 <li>fixes for Windows and initial thread support on Win32: Igor and Serguei 1516 Narojnyi</li> 1517 <li>Cygwin patch from Robert Collins</li> 1518 <li>added xmlSetEntityReferenceFunc() for Keith Isdale work on xsldbg</li> 1519</ul> 1520 1521<h3>2.4.12: Dec 7 2001</h3> 1522<ul> 1523 <li>a few bug fixes: thread (Gary Pennington), xmllint (Geert Kloosterman), 1524 XML parser (Robin Berjon), XPointer (Danny Jamshy), I/O cleanups 1525 (robert)</li> 1526 <li>Eric Lavigne contributed project files for MacOS</li> 1527 <li>some makefiles cleanups</li> 1528</ul> 1529 1530<h3>2.4.11: Nov 26 2001</h3> 1531<ul> 1532 <li>fixed a couple of errors in the includes, fixed a few bugs, some code 1533 cleanups</li> 1534 <li>xmllint man pages improvement by Heiko Rupp</li> 1535 <li>updated VMS build instructions from John A Fotheringham</li> 1536 <li>Windows Makefiles updates from Igor</li> 1537</ul> 1538 1539<h3>2.4.10: Nov 10 2001</h3> 1540<ul> 1541 <li>URI escaping fix (Joel Young)</li> 1542 <li>added xmlGetNodePath() (for paths or XPointers generation)</li> 1543 <li>Fixes namespace handling problems when using DTD and validation</li> 1544 <li>improvements on xmllint: Morus Walter patches for --format and 1545 --encode, Stefan Kost and Heiko Rupp improvements on the --shell</li> 1546 <li>fixes for xmlcatalog linking pointed by Weiqi Gao</li> 1547 <li>fixes to the HTML parser</li> 1548</ul> 1549 1550<h3>2.4.9: Nov 6 2001</h3> 1551<ul> 1552 <li>fixes more catalog bugs</li> 1553 <li>avoid a compilation problem, improve xmlGetLineNo()</li> 1554</ul> 1555 1556<h3>2.4.8: Nov 4 2001</h3> 1557<ul> 1558 <li>fixed SGML catalogs broken in previous release, updated xmlcatalog 1559 tool</li> 1560 <li>fixed a compile errors and some includes troubles.</li> 1561</ul> 1562 1563<h3>2.4.7: Oct 30 2001</h3> 1564<ul> 1565 <li>exported some debugging interfaces</li> 1566 <li>serious rewrite of the catalog code</li> 1567 <li>integrated Gary Pennington thread safety patch, added configure option 1568 and regression tests</li> 1569 <li>removed an HTML parser bug</li> 1570 <li>fixed a couple of potentially serious validation bugs</li> 1571 <li>integrated the SGML DocBook support in xmllint</li> 1572 <li>changed the nanoftp anonymous login passwd</li> 1573 <li>some I/O cleanup and a couple of interfaces for Perl wrapper</li> 1574 <li>general bug fixes</li> 1575 <li>updated xmllint man page by John Fleck</li> 1576 <li>some VMS and Windows updates</li> 1577</ul> 1578 1579<h3>2.4.6: Oct 10 2001</h3> 1580<ul> 1581 <li>added an updated man pages by John Fleck</li> 1582 <li>portability and configure fixes</li> 1583 <li>an infinite loop on the HTML parser was removed (William)</li> 1584 <li>Windows makefile patches from Igor</li> 1585 <li>fixed half a dozen bugs reported for libxml or libxslt</li> 1586 <li>updated xmlcatalog to be able to modify SGML super catalogs</li> 1587</ul> 1588 1589<h3>2.4.5: Sep 14 2001</h3> 1590<ul> 1591 <li>Remove a few annoying bugs in 2.4.4</li> 1592 <li>forces the HTML serializer to output decimal charrefs since some 1593 version of Netscape can't handle hexadecimal ones</li> 1594</ul> 1595 1596<h3>1.8.16: Sep 14 2001</h3> 1597<ul> 1598 <li>maintenance release of the old libxml1 branch, couple of bug and 1599 portability fixes</li> 1600</ul> 1601 1602<h3>2.4.4: Sep 12 2001</h3> 1603<ul> 1604 <li>added --convert to xmlcatalog, bug fixes and cleanups of XML 1605 Catalog</li> 1606 <li>a few bug fixes and some portability changes</li> 1607 <li>some documentation cleanups</li> 1608</ul> 1609 1610<h3>2.4.3: Aug 23 2001</h3> 1611<ul> 1612 <li>XML Catalog support see the doc</li> 1613 <li>New NaN/Infinity floating point code</li> 1614 <li>A few bug fixes</li> 1615</ul> 1616 1617<h3>2.4.2: Aug 15 2001</h3> 1618<ul> 1619 <li>adds xmlLineNumbersDefault() to control line number generation</li> 1620 <li>lot of bug fixes</li> 1621 <li>the Microsoft MSC projects files should now be up to date</li> 1622 <li>inheritance of namespaces from DTD defaulted attributes</li> 1623 <li>fixes a serious potential security bug</li> 1624 <li>added a --format option to xmllint</li> 1625</ul> 1626 1627<h3>2.4.1: July 24 2001</h3> 1628<ul> 1629 <li>possibility to keep line numbers in the tree</li> 1630 <li>some computation NaN fixes</li> 1631 <li>extension of the XPath API</li> 1632 <li>cleanup for alpha and ia64 targets</li> 1633 <li>patch to allow saving through HTTP PUT or POST</li> 1634</ul> 1635 1636<h3>2.4.0: July 10 2001</h3> 1637<ul> 1638 <li>Fixed a few bugs in XPath, validation, and tree handling.</li> 1639 <li>Fixed XML Base implementation, added a couple of examples to the 1640 regression tests</li> 1641 <li>A bit of cleanup</li> 1642</ul> 1643 1644<h3>2.3.14: July 5 2001</h3> 1645<ul> 1646 <li>fixed some entities problems and reduce memory requirement when 1647 substituting them</li> 1648 <li>lots of improvements in the XPath queries interpreter can be 1649 substantially faster</li> 1650 <li>Makefiles and configure cleanups</li> 1651 <li>Fixes to XPath variable eval, and compare on empty node set</li> 1652 <li>HTML tag closing bug fixed</li> 1653 <li>Fixed an URI reference computation problem when validating</li> 1654</ul> 1655 1656<h3>2.3.13: June 28 2001</h3> 1657<ul> 1658 <li>2.3.12 configure.in was broken as well as the push mode XML parser</li> 1659 <li>a few more fixes for compilation on Windows MSC by Yon Derek</li> 1660</ul> 1661 1662<h3>1.8.14: June 28 2001</h3> 1663<ul> 1664 <li>Zbigniew Chyla gave a patch to use the old XML parser in push mode</li> 1665 <li>Small Makefile fix</li> 1666</ul> 1667 1668<h3>2.3.12: June 26 2001</h3> 1669<ul> 1670 <li>lots of cleanup</li> 1671 <li>a couple of validation fix</li> 1672 <li>fixed line number counting</li> 1673 <li>fixed serious problems in the XInclude processing</li> 1674 <li>added support for UTF8 BOM at beginning of entities</li> 1675 <li>fixed a strange gcc optimizer bugs in xpath handling of float, gcc-3.0 1676 miscompile uri.c (William), Thomas Leitner provided a fix for the 1677 optimizer on Tru64</li> 1678 <li>incorporated Yon Derek and Igor Zlatkovic fixes and improvements for 1679 compilation on Windows MSC</li> 1680 <li>update of libxml-doc.el (Felix Natter)</li> 1681 <li>fixed 2 bugs in URI normalization code</li> 1682</ul> 1683 1684<h3>2.3.11: June 17 2001</h3> 1685<ul> 1686 <li>updates to trio, Makefiles and configure should fix some portability 1687 problems (alpha)</li> 1688 <li>fixed some HTML serialization problems (pre, script, and block/inline 1689 handling), added encoding aware APIs, cleanup of this code</li> 1690 <li>added xmlHasNsProp()</li> 1691 <li>implemented a specific PI for encoding support in the DocBook SGML 1692 parser</li> 1693 <li>some XPath fixes (-Infinity, / as a function parameter and namespaces 1694 node selection)</li> 1695 <li>fixed a performance problem and an error in the validation code</li> 1696 <li>fixed XInclude routine to implement the recursive behaviour</li> 1697 <li>fixed xmlFreeNode problem when libxml is included statically twice</li> 1698 <li>added --version to xmllint for bug reports</li> 1699</ul> 1700 1701<h3>2.3.10: June 1 2001</h3> 1702<ul> 1703 <li>fixed the SGML catalog support</li> 1704 <li>a number of reported bugs got fixed, in XPath, iconv detection, 1705 XInclude processing</li> 1706 <li>XPath string function should now handle unicode correctly</li> 1707</ul> 1708 1709<h3>2.3.9: May 19 2001</h3> 1710 1711<p>Lots of bugfixes, and added a basic SGML catalog support:</p> 1712<ul> 1713 <li>HTML push bugfix #54891 and another patch from Jonas Borgstr�m</li> 1714 <li>some serious speed optimization again</li> 1715 <li>some documentation cleanups</li> 1716 <li>trying to get better linking on Solaris (-R)</li> 1717 <li>XPath API cleanup from Thomas Broyer</li> 1718 <li>Validation bug fixed #54631, added a patch from Gary Pennington, fixed 1719 xmlValidGetValidElements()</li> 1720 <li>Added an INSTALL file</li> 1721 <li>Attribute removal added to API: #54433</li> 1722 <li>added a basic support for SGML catalogs</li> 1723 <li>fixed xmlKeepBlanksDefault(0) API</li> 1724 <li>bugfix in xmlNodeGetLang()</li> 1725 <li>fixed a small configure portability problem</li> 1726 <li>fixed an inversion of SYSTEM and PUBLIC identifier in HTML document</li> 1727</ul> 1728 1729<h3>1.8.13: May 14 2001</h3> 1730<ul> 1731 <li>bugfixes release of the old libxml1 branch used by Gnome</li> 1732</ul> 1733 1734<h3>2.3.8: May 3 2001</h3> 1735<ul> 1736 <li>Integrated an SGML DocBook parser for the Gnome project</li> 1737 <li>Fixed a few things in the HTML parser</li> 1738 <li>Fixed some XPath bugs raised by XSLT use, tried to fix the floating 1739 point portability issue</li> 1740 <li>Speed improvement (8M/s for SAX, 3M/s for DOM, 1.5M/s for 1741 DOM+validation using the XML REC as input and a 700MHz celeron).</li> 1742 <li>incorporated more Windows cleanup</li> 1743 <li>added xmlSaveFormatFile()</li> 1744 <li>fixed problems in copying nodes with entities references (gdome)</li> 1745 <li>removed some troubles surrounding the new validation module</li> 1746</ul> 1747 1748<h3>2.3.7: April 22 2001</h3> 1749<ul> 1750 <li>lots of small bug fixes, corrected XPointer</li> 1751 <li>Non deterministic content model validation support</li> 1752 <li>added xmlDocCopyNode for gdome2</li> 1753 <li>revamped the way the HTML parser handles end of tags</li> 1754 <li>XPath: corrections of namespaces support and number formatting</li> 1755 <li>Windows: Igor Zlatkovic patches for MSC compilation</li> 1756 <li>HTML output fixes from P C Chow and William M. Brack</li> 1757 <li>Improved validation speed sensible for DocBook</li> 1758 <li>fixed a big bug with ID declared in external parsed entities</li> 1759 <li>portability fixes, update of Trio from Bjorn Reese</li> 1760</ul> 1761 1762<h3>2.3.6: April 8 2001</h3> 1763<ul> 1764 <li>Code cleanup using extreme gcc compiler warning options, found and 1765 cleared half a dozen potential problem</li> 1766 <li>the Eazel team found an XML parser bug</li> 1767 <li>cleaned up the user of some of the string formatting function. used the 1768 trio library code to provide the one needed when the platform is missing 1769 them</li> 1770 <li>xpath: removed a memory leak and fixed the predicate evaluation 1771 problem, extended the testsuite and cleaned up the result. XPointer seems 1772 broken ...</li> 1773</ul> 1774 1775<h3>2.3.5: Mar 23 2001</h3> 1776<ul> 1777 <li>Biggest change is separate parsing and evaluation of XPath expressions, 1778 there is some new APIs for this too</li> 1779 <li>included a number of bug fixes(XML push parser, 51876, notations, 1780 52299)</li> 1781 <li>Fixed some portability issues</li> 1782</ul> 1783 1784<h3>2.3.4: Mar 10 2001</h3> 1785<ul> 1786 <li>Fixed bugs #51860 and #51861</li> 1787 <li>Added a global variable xmlDefaultBufferSize to allow default buffer 1788 size to be application tunable.</li> 1789 <li>Some cleanup in the validation code, still a bug left and this part 1790 should probably be rewritten to support ambiguous content model :-\</li> 1791 <li>Fix a couple of serious bugs introduced or raised by changes in 2.3.3 1792 parser</li> 1793 <li>Fixed another bug in xmlNodeGetContent()</li> 1794 <li>Bjorn fixed XPath node collection and Number formatting</li> 1795 <li>Fixed a loop reported in the HTML parsing</li> 1796 <li>blank space are reported even if the Dtd content model proves that they 1797 are formatting spaces, this is for XML conformance</li> 1798</ul> 1799 1800<h3>2.3.3: Mar 1 2001</h3> 1801<ul> 1802 <li>small change in XPath for XSLT</li> 1803 <li>documentation cleanups</li> 1804 <li>fix in validation by Gary Pennington</li> 1805 <li>serious parsing performances improvements</li> 1806</ul> 1807 1808<h3>2.3.2: Feb 24 2001</h3> 1809<ul> 1810 <li>chasing XPath bugs, found a bunch, completed some TODO</li> 1811 <li>fixed a Dtd parsing bug</li> 1812 <li>fixed a bug in xmlNodeGetContent</li> 1813 <li>ID/IDREF support partly rewritten by Gary Pennington</li> 1814</ul> 1815 1816<h3>2.3.1: Feb 15 2001</h3> 1817<ul> 1818 <li>some XPath and HTML bug fixes for XSLT</li> 1819 <li>small extension of the hash table interfaces for DOM gdome2 1820 implementation</li> 1821 <li>A few bug fixes</li> 1822</ul> 1823 1824<h3>2.3.0: Feb 8 2001 (2.2.12 was on 25 Jan but I didn't kept track)</h3> 1825<ul> 1826 <li>Lots of XPath bug fixes</li> 1827 <li>Add a mode with Dtd lookup but without validation error reporting for 1828 XSLT</li> 1829 <li>Add support for text node without escaping (XSLT)</li> 1830 <li>bug fixes for xmlCheckFilename</li> 1831 <li>validation code bug fixes from Gary Pennington</li> 1832 <li>Patch from Paul D. Smith correcting URI path normalization</li> 1833 <li>Patch to allow simultaneous install of libxml-devel and 1834 libxml2-devel</li> 1835 <li>the example Makefile is now fixed</li> 1836 <li>added HTML to the RPM packages</li> 1837 <li>tree copying bugfixes</li> 1838 <li>updates to Windows makefiles</li> 1839 <li>optimization patch from Bjorn Reese</li> 1840</ul> 1841 1842<h3>2.2.11: Jan 4 2001</h3> 1843<ul> 1844 <li>bunch of bug fixes (memory I/O, xpath, ftp/http, ...)</li> 1845 <li>added htmlHandleOmittedElem()</li> 1846 <li>Applied Bjorn Reese's IPV6 first patch</li> 1847 <li>Applied Paul D. Smith patches for validation of XInclude results</li> 1848 <li>added XPointer xmlns() new scheme support</li> 1849</ul> 1850 1851<h3>2.2.10: Nov 25 2000</h3> 1852<ul> 1853 <li>Fix the Windows problems of 2.2.8</li> 1854 <li>integrate OpenVMS patches</li> 1855 <li>better handling of some nasty HTML input</li> 1856 <li>Improved the XPointer implementation</li> 1857 <li>integrate a number of provided patches</li> 1858</ul> 1859 1860<h3>2.2.9: Nov 25 2000</h3> 1861<ul> 1862 <li>erroneous release :-(</li> 1863</ul> 1864 1865<h3>2.2.8: Nov 13 2000</h3> 1866<ul> 1867 <li>First version of <a href="http://www.w3.org/TR/xinclude">XInclude</a> 1868 support</li> 1869 <li>Patch in conditional section handling</li> 1870 <li>updated MS compiler project</li> 1871 <li>fixed some XPath problems</li> 1872 <li>added an URI escaping function</li> 1873 <li>some other bug fixes</li> 1874</ul> 1875 1876<h3>2.2.7: Oct 31 2000</h3> 1877<ul> 1878 <li>added message redirection</li> 1879 <li>XPath improvements (thanks TOM !)</li> 1880 <li>xmlIOParseDTD() added</li> 1881 <li>various small fixes in the HTML, URI, HTTP and XPointer support</li> 1882 <li>some cleanup of the Makefile, autoconf and the distribution content</li> 1883</ul> 1884 1885<h3>2.2.6: Oct 25 2000:</h3> 1886<ul> 1887 <li>Added an hash table module, migrated a number of internal structure to 1888 those</li> 1889 <li>Fixed a posteriori validation problems</li> 1890 <li>HTTP module cleanups</li> 1891 <li>HTML parser improvements (tag errors, script/style handling, attribute 1892 normalization)</li> 1893 <li>coalescing of adjacent text nodes</li> 1894 <li>couple of XPath bug fixes, exported the internal API</li> 1895</ul> 1896 1897<h3>2.2.5: Oct 15 2000:</h3> 1898<ul> 1899 <li>XPointer implementation and testsuite</li> 1900 <li>Lot of XPath fixes, added variable and functions registration, more 1901 tests</li> 1902 <li>Portability fixes, lots of enhancements toward an easy Windows build 1903 and release</li> 1904 <li>Late validation fixes</li> 1905 <li>Integrated a lot of contributed patches</li> 1906 <li>added memory management docs</li> 1907 <li>a performance problem when using large buffer seems fixed</li> 1908</ul> 1909 1910<h3>2.2.4: Oct 1 2000:</h3> 1911<ul> 1912 <li>main XPath problem fixed</li> 1913 <li>Integrated portability patches for Windows</li> 1914 <li>Serious bug fixes on the URI and HTML code</li> 1915</ul> 1916 1917<h3>2.2.3: Sep 17 2000</h3> 1918<ul> 1919 <li>bug fixes</li> 1920 <li>cleanup of entity handling code</li> 1921 <li>overall review of all loops in the parsers, all sprintf usage has been 1922 checked too</li> 1923 <li>Far better handling of larges Dtd. Validating against DocBook XML Dtd 1924 works smoothly now.</li> 1925</ul> 1926 1927<h3>1.8.10: Sep 6 2000</h3> 1928<ul> 1929 <li>bug fix release for some Gnome projects</li> 1930</ul> 1931 1932<h3>2.2.2: August 12 2000</h3> 1933<ul> 1934 <li>mostly bug fixes</li> 1935 <li>started adding routines to access xml parser context options</li> 1936</ul> 1937 1938<h3>2.2.1: July 21 2000</h3> 1939<ul> 1940 <li>a purely bug fixes release</li> 1941 <li>fixed an encoding support problem when parsing from a memory block</li> 1942 <li>fixed a DOCTYPE parsing problem</li> 1943 <li>removed a bug in the function allowing to override the memory 1944 allocation routines</li> 1945</ul> 1946 1947<h3>2.2.0: July 14 2000</h3> 1948<ul> 1949 <li>applied a lot of portability fixes</li> 1950 <li>better encoding support/cleanup and saving (content is now always 1951 encoded in UTF-8)</li> 1952 <li>the HTML parser now correctly handles encodings</li> 1953 <li>added xmlHasProp()</li> 1954 <li>fixed a serious problem with &#38;</li> 1955 <li>propagated the fix to FTP client</li> 1956 <li>cleanup, bugfixes, etc ...</li> 1957 <li>Added a page about <a href="encoding.html">libxml Internationalization 1958 support</a></li> 1959</ul> 1960 1961<h3>1.8.9: July 9 2000</h3> 1962<ul> 1963 <li>fixed the spec the RPMs should be better</li> 1964 <li>fixed a serious bug in the FTP implementation, released 1.8.9 to solve 1965 rpmfind users problem</li> 1966</ul> 1967 1968<h3>2.1.1: July 1 2000</h3> 1969<ul> 1970 <li>fixes a couple of bugs in the 2.1.0 packaging</li> 1971 <li>improvements on the HTML parser</li> 1972</ul> 1973 1974<h3>2.1.0 and 1.8.8: June 29 2000</h3> 1975<ul> 1976 <li>1.8.8 is mostly a commodity package for upgrading to libxml2 according 1977 to <a href="upgrade.html">new instructions</a>. It fixes a nasty problem 1978 about &#38; charref parsing</li> 1979 <li>2.1.0 also ease the upgrade from libxml v1 to the recent version. it 1980 also contains numerous fixes and enhancements: 1981 <ul> 1982 <li>added xmlStopParser() to stop parsing</li> 1983 <li>improved a lot parsing speed when there is large CDATA blocs</li> 1984 <li>includes XPath patches provided by Picdar Technology</li> 1985 <li>tried to fix as much as possible DTD validation and namespace 1986 related problems</li> 1987 <li>output to a given encoding has been added/tested</li> 1988 <li>lot of various fixes</li> 1989 </ul> 1990 </li> 1991</ul> 1992 1993<h3>2.0.0: Apr 12 2000</h3> 1994<ul> 1995 <li>First public release of libxml2. If you are using libxml, it's a good 1996 idea to check the 1.x to 2.x upgrade instructions. NOTE: while initially 1997 scheduled for Apr 3 the release occurred only on Apr 12 due to massive 1998 workload.</li> 1999 <li>The include are now located under $prefix/include/libxml (instead of 2000 $prefix/include/gnome-xml), they also are referenced by 2001 <pre>#include <libxml/xxx.h></pre> 2002 <p>instead of</p> 2003 <pre>#include "xxx.h"</pre> 2004 </li> 2005 <li>a new URI module for parsing URIs and following strictly RFC 2396</li> 2006 <li>the memory allocation routines used by libxml can now be overloaded 2007 dynamically by using xmlMemSetup()</li> 2008 <li>The previously CVS only tool tester has been renamed 2009 <strong>xmllint</strong> and is now installed as part of the libxml2 2010 package</li> 2011 <li>The I/O interface has been revamped. There is now ways to plug in 2012 specific I/O modules, either at the URI scheme detection level using 2013 xmlRegisterInputCallbacks() or by passing I/O functions when creating a 2014 parser context using xmlCreateIOParserCtxt()</li> 2015 <li>there is a C preprocessor macro LIBXML_VERSION providing the version 2016 number of the libxml module in use</li> 2017 <li>a number of optional features of libxml can now be excluded at 2018 configure time (FTP/HTTP/HTML/XPath/Debug)</li> 2019</ul> 2020 2021<h3>2.0.0beta: Mar 14 2000</h3> 2022<ul> 2023 <li>This is a first Beta release of libxml version 2</li> 2024 <li>It's available only from<a href="ftp://xmlsoft.org/">xmlsoft.org 2025 FTP</a>, it's packaged as libxml2-2.0.0beta and available as tar and 2026 RPMs</li> 2027 <li>This version is now the head in the Gnome CVS base, the old one is 2028 available under the tag LIB_XML_1_X</li> 2029 <li>This includes a very large set of changes. From a programmatic point 2030 of view applications should not have to be modified too much, check the 2031 <a href="upgrade.html">upgrade page</a></li> 2032 <li>Some interfaces may changes (especially a bit about encoding).</li> 2033 <li>the updates includes: 2034 <ul> 2035 <li>fix I18N support. ISO-Latin-x/UTF-8/UTF-16 (nearly) seems correctly 2036 handled now</li> 2037 <li>Better handling of entities, especially well-formedness checking 2038 and proper PEref extensions in external subsets</li> 2039 <li>DTD conditional sections</li> 2040 <li>Validation now correctly handle entities content</li> 2041 <li><a href="http://rpmfind.net/tools/gdome/messages/0039.html">change 2042 structures to accommodate DOM</a></li> 2043 </ul> 2044 </li> 2045 <li>Serious progress were made toward compliance, <a 2046 href="conf/result.html">here are the result of the test</a> against the 2047 OASIS testsuite (except the Japanese tests since I don't support that 2048 encoding yet). This URL is rebuilt every couple of hours using the CVS 2049 head version.</li> 2050</ul> 2051 2052<h3>1.8.7: Mar 6 2000</h3> 2053<ul> 2054 <li>This is a bug fix release:</li> 2055 <li>It is possible to disable the ignorable blanks heuristic used by 2056 libxml-1.x, a new function xmlKeepBlanksDefault(0) will allow this. Note 2057 that for adherence to XML spec, this behaviour will be disabled by 2058 default in 2.x . The same function will allow to keep compatibility for 2059 old code.</li> 2060 <li>Blanks in <a> </a> constructs are not ignored anymore, 2061 avoiding heuristic is really the Right Way :-\</li> 2062 <li>The unchecked use of snprintf which was breaking libxml-1.8.6 2063 compilation on some platforms has been fixed</li> 2064 <li>nanoftp.c nanohttp.c: Fixed '#' and '?' stripping when processing 2065 URIs</li> 2066</ul> 2067 2068<h3>1.8.6: Jan 31 2000</h3> 2069<ul> 2070 <li>added a nanoFTP transport module, debugged until the new version of <a 2071 href="http://rpmfind.net/linux/rpm2html/rpmfind.html">rpmfind</a> can use 2072 it without troubles</li> 2073</ul> 2074 2075<h3>1.8.5: Jan 21 2000</h3> 2076<ul> 2077 <li>adding APIs to parse a well balanced chunk of XML (production <a 2078 href="http://www.w3.org/TR/REC-xml#NT-content">[43] content</a> of the 2079 XML spec)</li> 2080 <li>fixed a hideous bug in xmlGetProp pointed by Rune.Djurhuus@fast.no</li> 2081 <li>Jody Goldberg <jgoldberg@home.com> provided another patch trying 2082 to solve the zlib checks problems</li> 2083 <li>The current state in gnome CVS base is expected to ship as 1.8.5 with 2084 gnumeric soon</li> 2085</ul> 2086 2087<h3>1.8.4: Jan 13 2000</h3> 2088<ul> 2089 <li>bug fixes, reintroduced xmlNewGlobalNs(), fixed xmlNewNs()</li> 2090 <li>all exit() call should have been removed from libxml</li> 2091 <li>fixed a problem with INCLUDE_WINSOCK on WIN32 platform</li> 2092 <li>added newDocFragment()</li> 2093</ul> 2094 2095<h3>1.8.3: Jan 5 2000</h3> 2096<ul> 2097 <li>a Push interface for the XML and HTML parsers</li> 2098 <li>a shell-like interface to the document tree (try tester --shell :-)</li> 2099 <li>lots of bug fixes and improvement added over XMas holidays</li> 2100 <li>fixed the DTD parsing code to work with the xhtml DTD</li> 2101 <li>added xmlRemoveProp(), xmlRemoveID() and xmlRemoveRef()</li> 2102 <li>Fixed bugs in xmlNewNs()</li> 2103 <li>External entity loading code has been revamped, now it uses 2104 xmlLoadExternalEntity(), some fix on entities processing were added</li> 2105 <li>cleaned up WIN32 includes of socket stuff</li> 2106</ul> 2107 2108<h3>1.8.2: Dec 21 1999</h3> 2109<ul> 2110 <li>I got another problem with includes and C++, I hope this issue is fixed 2111 for good this time</li> 2112 <li>Added a few tree modification functions: xmlReplaceNode, 2113 xmlAddPrevSibling, xmlAddNextSibling, xmlNodeSetName and 2114 xmlDocSetRootElement</li> 2115 <li>Tried to improve the HTML output with help from <a 2116 href="mailto:clahey@umich.edu">Chris Lahey</a></li> 2117</ul> 2118 2119<h3>1.8.1: Dec 18 1999</h3> 2120<ul> 2121 <li>various patches to avoid troubles when using libxml with C++ compilers 2122 the "namespace" keyword and C escaping in include files</li> 2123 <li>a problem in one of the core macros IS_CHAR was corrected</li> 2124 <li>fixed a bug introduced in 1.8.0 breaking default namespace processing, 2125 and more specifically the Dia application</li> 2126 <li>fixed a posteriori validation (validation after parsing, or by using a 2127 Dtd not specified in the original document)</li> 2128 <li>fixed a bug in</li> 2129</ul> 2130 2131<h3>1.8.0: Dec 12 1999</h3> 2132<ul> 2133 <li>cleanup, especially memory wise</li> 2134 <li>the parser should be more reliable, especially the HTML one, it should 2135 not crash, whatever the input !</li> 2136 <li>Integrated various patches, especially a speedup improvement for large 2137 dataset from <a href="mailto:cnygard@bellatlantic.net">Carl Nygard</a>, 2138 configure with --with-buffers to enable them.</li> 2139 <li>attribute normalization, oops should have been added long ago !</li> 2140 <li>attributes defaulted from DTDs should be available, xmlSetProp() now 2141 does entities escaping by default.</li> 2142</ul> 2143 2144<h3>1.7.4: Oct 25 1999</h3> 2145<ul> 2146 <li>Lots of HTML improvement</li> 2147 <li>Fixed some errors when saving both XML and HTML</li> 2148 <li>More examples, the regression tests should now look clean</li> 2149 <li>Fixed a bug with contiguous charref</li> 2150</ul> 2151 2152<h3>1.7.3: Sep 29 1999</h3> 2153<ul> 2154 <li>portability problems fixed</li> 2155 <li>snprintf was used unconditionally, leading to link problems on system 2156 were it's not available, fixed</li> 2157</ul> 2158 2159<h3>1.7.1: Sep 24 1999</h3> 2160<ul> 2161 <li>The basic type for strings manipulated by libxml has been renamed in 2162 1.7.1 from <strong>CHAR</strong> to <strong>xmlChar</strong>. The reason 2163 is that CHAR was conflicting with a predefined type on Windows. However 2164 on non WIN32 environment, compatibility is provided by the way of a 2165 <strong>#define </strong>.</li> 2166 <li>Changed another error : the use of a structure field called errno, and 2167 leading to troubles on platforms where it's a macro</li> 2168</ul> 2169 2170<h3>1.7.0: Sep 23 1999</h3> 2171<ul> 2172 <li>Added the ability to fetch remote DTD or parsed entities, see the <a 2173 href="html/libxml-nanohttp.html">nanohttp</a> module.</li> 2174 <li>Added an errno to report errors by another mean than a simple printf 2175 like callback</li> 2176 <li>Finished ID/IDREF support and checking when validation</li> 2177 <li>Serious memory leaks fixed (there is now a <a 2178 href="html/libxml-xmlmemory.html">memory wrapper</a> module)</li> 2179 <li>Improvement of <a href="http://www.w3.org/TR/xpath">XPath</a> 2180 implementation</li> 2181 <li>Added an HTML parser front-end</li> 2182</ul> 2183 2184<h2><a name="XML">XML</a></h2> 2185 2186<p><a href="http://www.w3.org/TR/REC-xml">XML is a standard</a> for 2187markup-based structured documents. Here is <a name="example">an example XML 2188document</a>:</p> 2189<pre><?xml version="1.0"?> 2190<EXAMPLE prop1="gnome is great" prop2="&amp; linux too"> 2191 <head> 2192 <title>Welcome to Gnome</title> 2193 </head> 2194 <chapter> 2195 <title>The Linux adventure</title> 2196 <p>bla bla bla ...</p> 2197 <image href="linus.gif"/> 2198 <p>...</p> 2199 </chapter> 2200</EXAMPLE></pre> 2201 2202<p>The first line specifies that it is an XML document and gives useful 2203information about its encoding. Then the rest of the document is a text 2204format whose structure is specified by tags between brackets. <strong>Each 2205tag opened has to be closed</strong>. XML is pedantic about this. However, if 2206a tag is empty (no content), a single tag can serve as both the opening and 2207closing tag if it ends with <code>/></code> rather than with 2208<code>></code>. Note that, for example, the image tag has no content (just 2209an attribute) and is closed by ending the tag with <code>/></code>.</p> 2210 2211<p>XML can be applied successfully to a wide range of tasks, ranging from 2212long term structured document maintenance (where it follows the steps of 2213SGML) to simple data encoding mechanisms like configuration file formatting 2214(glade), spreadsheets (gnumeric), or even shorter lived documents such as 2215WebDAV where it is used to encode remote calls between a client and a 2216server.</p> 2217 2218<h2><a name="XSLT">XSLT</a></h2> 2219 2220<p>Check <a href="http://xmlsoft.org/XSLT">the separate libxslt page</a></p> 2221 2222<p><a href="http://www.w3.org/TR/xslt">XSL Transformations</a>, is a 2223language for transforming XML documents into other XML documents (or 2224HTML/textual output).</p> 2225 2226<p>A separate library called libxslt is available implementing XSLT-1.0 for 2227libxml2. This module "libxslt" too can be found in the Gnome CVS base.</p> 2228 2229<p>You can check the <a 2230href="http://cvs.gnome.org/lxr/source/libxslt/FEATURES">features</a> 2231supported and the progresses on the <a 2232href="http://cvs.gnome.org/lxr/source/libxslt/ChangeLog" 2233name="Changelog">Changelog</a>.</p> 2234 2235<h2><a name="Python">Python and bindings</a></h2> 2236 2237<p>There are a number of language bindings and wrappers available for 2238libxml2, the list below is not exhaustive. Please contact the <a 2239href="http://mail.gnome.org/mailman/listinfo/xml-bindings">xml-bindings@gnome.org</a> 2240(<a href="http://mail.gnome.org/archives/xml-bindings/">archives</a>) in 2241order to get updates to this list or to discuss the specific topic of libxml2 2242or libxslt wrappers or bindings:</p> 2243<ul> 2244 <li><a href="http://libxmlplusplus.sourceforge.net/">Libxml++</a> seems the 2245 most up-to-date C++ bindings for libxml2, check the <a 2246 href="http://libxmlplusplus.sourceforge.net/reference/html/hierarchy.html">documentation</a> 2247 and the <a 2248 href="http://cvs.sourceforge.net/cgi-bin/viewcvs.cgi/libxmlplusplus/libxml%2b%2b/examples/">examples</a>.</li> 2249 <li>There is another <a href="http://libgdome-cpp.berlios.de/">C++ wrapper 2250 based on the gdome2 bindings</a> maintained by Tobias Peters.</li> 2251 <li>and a third C++ wrapper by Peter Jones <pjones@pmade.org> 2252 <p>Website: <a 2253 href="http://pmade.org/pjones/software/xmlwrapp/">http://pmade.org/pjones/software/xmlwrapp/</a></p> 2254 </li> 2255 <li><a 2256 href="http://mail.gnome.org/archives/xml/2001-March/msg00014.html">Matt 2257 Sergeant</a> developed <a 2258 href="http://axkit.org/download/">XML::LibXSLT</a>, a Perl wrapper for 2259 libxml2/libxslt as part of the <a href="http://axkit.com/">AxKit XML 2260 application server</a>.</li> 2261 <li>If you're interested into scripting XML processing, have a look at <a 2262 href="http://xsh.sourceforge.net/">XSH</a> an XML editing shell based on 2263 Libxml2 Perl bindings.</li> 2264 <li><a href="mailto:dkuhlman@cutter.rexx.com">Dave Kuhlman</a> provides an 2265 earlier version of the libxml/libxslt <a 2266 href="http://www.rexx.com/~dkuhlman">wrappers for Python</a>.</li> 2267 <li>Gopal.V and Peter Minten develop <a 2268 href="http://savannah.gnu.org/projects/libxmlsharp">libxml#</a>, a set of 2269 C# libxml2 bindings.</li> 2270 <li>Petr Kozelka provides <a 2271 href="http://sourceforge.net/projects/libxml2-pas">Pascal units to glue 2272 libxml2</a> with Kylix, Delphi and other Pascal compilers.</li> 2273 <li>Uwe Fechner also provides <a 2274 href="http://sourceforge.net/projects/idom2-pas/">idom2</a>, a DOM2 2275 implementation for Kylix2/D5/D6 from Borland.</li> 2276 <li>Wai-Sun "Squidster" Chia provides <a 2277 href="http://www.rubycolor.org/arc/redist/">bindings for Ruby</a> and 2278 libxml2 bindings are also available in Ruby through the <a 2279 href="http://libgdome-ruby.berlios.de/">libgdome-ruby</a> module 2280 maintained by Tobias Peters.</li> 2281 <li>Steve Ball and contributors maintains <a 2282 href="http://tclxml.sourceforge.net/">libxml2 and libxslt bindings for 2283 Tcl</a>.</li> 2284 <li>There is support for libxml2 in the DOM module of PHP.</li> 2285 <li><a href="http://savannah.gnu.org/projects/classpathx/">LibxmlJ</a> is 2286 an effort to create a 100% JAXP-compatible Java wrapper for libxml2 and 2287 libxslt as part of GNU ClasspathX project.</li> 2288 <li>Patrick McPhee provides Rexx bindings fof libxml2 and libxslt, look for 2289 <a href="http://www.interlog.com/~ptjm/software.html">RexxXML</a>.</li> 2290 <li><a href="http://www.satimage.fr/software/en/xml_suite.html">Satimage</a> 2291 provides <a 2292 href="http://www.satimage.fr/software/en/downloads_osaxen.html">XMLLib 2293 osax</a>. This is an osax for Mac OS X with a set of commands to 2294 implement in AppleScript the XML DOM, XPATH and XSLT. Also includes 2295 commands for Property-lists (Apple's fast lookup table XML format.)</li> 2296 <li>Francesco Montorsi developped 2297<a href="https://sourceforge.net/project/showfiles.php?group_id=51305&package_id=45182">wxXml2</a> 2298 wrappers that interface libxml2, allowing wxWidgets applications to 2299 load/save/edit XML instances.</li> 2300</ul> 2301 2302<p>The distribution includes a set of Python bindings, which are guaranteed 2303to be maintained as part of the library in the future, though the Python 2304interface have not yet reached the completeness of the C API.</p> 2305 2306<p><a href="mailto:stephane.bidoul@softwareag.com">St�phane Bidoul</a> 2307maintains <a href="http://users.skynet.be/sbi/libxml-python/">a Windows port 2308of the Python bindings</a>.</p> 2309 2310<p>Note to people interested in building bindings, the API is formalized as 2311<a href="libxml2-api.xml">an XML API description file</a> which allows to 2312automate a large part of the Python bindings, this includes function 2313descriptions, enums, structures, typedefs, etc... The Python script used to 2314build the bindings is python/generator.py in the source distribution.</p> 2315 2316<p>To install the Python bindings there are 2 options:</p> 2317<ul> 2318 <li>If you use an RPM based distribution, simply install the <a 2319 href="http://rpmfind.net/linux/rpm2html/search.php?query=libxml2-python">libxml2-python 2320 RPM</a> (and if needed the <a 2321 href="http://rpmfind.net/linux/rpm2html/search.php?query=libxslt-python">libxslt-python 2322 RPM</a>).</li> 2323 <li>Otherwise use the <a href="ftp://xmlsoft.org/python/">libxml2-python 2324 module distribution</a> corresponding to your installed version of 2325 libxml2 and libxslt. Note that to install it you will need both libxml2 2326 and libxslt installed and run "python setup.py build install" in the 2327 module tree.</li> 2328</ul> 2329 2330<p>The distribution includes a set of examples and regression tests for the 2331python bindings in the <code>python/tests</code> directory. Here are some 2332excerpts from those tests:</p> 2333 2334<h3>tst.py:</h3> 2335 2336<p>This is a basic test of the file interface and DOM navigation:</p> 2337<pre>import libxml2, sys 2338 2339doc = libxml2.parseFile("tst.xml") 2340if doc.name != "tst.xml": 2341 print "doc.name failed" 2342 sys.exit(1) 2343root = doc.children 2344if root.name != "doc": 2345 print "root.name failed" 2346 sys.exit(1) 2347child = root.children 2348if child.name != "foo": 2349 print "child.name failed" 2350 sys.exit(1) 2351doc.freeDoc()</pre> 2352 2353<p>The Python module is called libxml2; parseFile is the equivalent of 2354xmlParseFile (most of the bindings are automatically generated, and the xml 2355prefix is removed and the casing convention are kept). All node seen at the 2356binding level share the same subset of accessors:</p> 2357<ul> 2358 <li><code>name</code> : returns the node name</li> 2359 <li><code>type</code> : returns a string indicating the node type</li> 2360 <li><code>content</code> : returns the content of the node, it is based on 2361 xmlNodeGetContent() and hence is recursive.</li> 2362 <li><code>parent</code> , <code>children</code>, <code>last</code>, 2363 <code>next</code>, <code>prev</code>, <code>doc</code>, 2364 <code>properties</code>: pointing to the associated element in the tree, 2365 those may return None in case no such link exists.</li> 2366</ul> 2367 2368<p>Also note the need to explicitly deallocate documents with freeDoc() . 2369Reference counting for libxml2 trees would need quite a lot of work to 2370function properly, and rather than risk memory leaks if not implemented 2371correctly it sounds safer to have an explicit function to free a tree. The 2372wrapper python objects like doc, root or child are them automatically garbage 2373collected.</p> 2374 2375<h3>validate.py:</h3> 2376 2377<p>This test check the validation interfaces and redirection of error 2378messages:</p> 2379<pre>import libxml2 2380 2381#deactivate error messages from the validation 2382def noerr(ctx, str): 2383 pass 2384 2385libxml2.registerErrorHandler(noerr, None) 2386 2387ctxt = libxml2.createFileParserCtxt("invalid.xml") 2388ctxt.validate(1) 2389ctxt.parseDocument() 2390doc = ctxt.doc() 2391valid = ctxt.isValid() 2392doc.freeDoc() 2393if valid != 0: 2394 print "validity check failed"</pre> 2395 2396<p>The first thing to notice is the call to registerErrorHandler(), it 2397defines a new error handler global to the library. It is used to avoid seeing 2398the error messages when trying to validate the invalid document.</p> 2399 2400<p>The main interest of that test is the creation of a parser context with 2401createFileParserCtxt() and how the behaviour can be changed before calling 2402parseDocument() . Similarly the informations resulting from the parsing phase 2403are also available using context methods.</p> 2404 2405<p>Contexts like nodes are defined as class and the libxml2 wrappers maps the 2406C function interfaces in terms of objects method as much as possible. The 2407best to get a complete view of what methods are supported is to look at the 2408libxml2.py module containing all the wrappers.</p> 2409 2410<h3>push.py:</h3> 2411 2412<p>This test show how to activate the push parser interface:</p> 2413<pre>import libxml2 2414 2415ctxt = libxml2.createPushParser(None, "<foo", 4, "test.xml") 2416ctxt.parseChunk("/>", 2, 1) 2417doc = ctxt.doc() 2418 2419doc.freeDoc()</pre> 2420 2421<p>The context is created with a special call based on the 2422xmlCreatePushParser() from the C library. The first argument is an optional 2423SAX callback object, then the initial set of data, the length and the name of 2424the resource in case URI-References need to be computed by the parser.</p> 2425 2426<p>Then the data are pushed using the parseChunk() method, the last call 2427setting the third argument terminate to 1.</p> 2428 2429<h3>pushSAX.py:</h3> 2430 2431<p>this test show the use of the event based parsing interfaces. In this case 2432the parser does not build a document, but provides callback information as 2433the parser makes progresses analyzing the data being provided:</p> 2434<pre>import libxml2 2435log = "" 2436 2437class callback: 2438 def startDocument(self): 2439 global log 2440 log = log + "startDocument:" 2441 2442 def endDocument(self): 2443 global log 2444 log = log + "endDocument:" 2445 2446 def startElement(self, tag, attrs): 2447 global log 2448 log = log + "startElement %s %s:" % (tag, attrs) 2449 2450 def endElement(self, tag): 2451 global log 2452 log = log + "endElement %s:" % (tag) 2453 2454 def characters(self, data): 2455 global log 2456 log = log + "characters: %s:" % (data) 2457 2458 def warning(self, msg): 2459 global log 2460 log = log + "warning: %s:" % (msg) 2461 2462 def error(self, msg): 2463 global log 2464 log = log + "error: %s:" % (msg) 2465 2466 def fatalError(self, msg): 2467 global log 2468 log = log + "fatalError: %s:" % (msg) 2469 2470handler = callback() 2471 2472ctxt = libxml2.createPushParser(handler, "<foo", 4, "test.xml") 2473chunk = " url='tst'>b" 2474ctxt.parseChunk(chunk, len(chunk), 0) 2475chunk = "ar</foo>" 2476ctxt.parseChunk(chunk, len(chunk), 1) 2477 2478reference = "startDocument:startElement foo {'url': 'tst'}:" + \ 2479 "characters: bar:endElement foo:endDocument:" 2480if log != reference: 2481 print "Error got: %s" % log 2482 print "Expected: %s" % reference</pre> 2483 2484<p>The key object in that test is the handler, it provides a number of entry 2485points which can be called by the parser as it makes progresses to indicate 2486the information set obtained. The full set of callback is larger than what 2487the callback class in that specific example implements (see the SAX 2488definition for a complete list). The wrapper will only call those supplied by 2489the object when activated. The startElement receives the names of the element 2490and a dictionary containing the attributes carried by this element.</p> 2491 2492<p>Also note that the reference string generated from the callback shows a 2493single character call even though the string "bar" is passed to the parser 2494from 2 different call to parseChunk()</p> 2495 2496<h3>xpath.py:</h3> 2497 2498<p>This is a basic test of XPath wrappers support</p> 2499<pre>import libxml2 2500 2501doc = libxml2.parseFile("tst.xml") 2502ctxt = doc.xpathNewContext() 2503res = ctxt.xpathEval("//*") 2504if len(res) != 2: 2505 print "xpath query: wrong node set size" 2506 sys.exit(1) 2507if res[0].name != "doc" or res[1].name != "foo": 2508 print "xpath query: wrong node set value" 2509 sys.exit(1) 2510doc.freeDoc() 2511ctxt.xpathFreeContext()</pre> 2512 2513<p>This test parses a file, then create an XPath context to evaluate XPath 2514expression on it. The xpathEval() method execute an XPath query and returns 2515the result mapped in a Python way. String and numbers are natively converted, 2516and node sets are returned as a tuple of libxml2 Python nodes wrappers. Like 2517the document, the XPath context need to be freed explicitly, also not that 2518the result of the XPath query may point back to the document tree and hence 2519the document must be freed after the result of the query is used.</p> 2520 2521<h3>xpathext.py:</h3> 2522 2523<p>This test shows how to extend the XPath engine with functions written in 2524python:</p> 2525<pre>import libxml2 2526 2527def foo(ctx, x): 2528 return x + 1 2529 2530doc = libxml2.parseFile("tst.xml") 2531ctxt = doc.xpathNewContext() 2532libxml2.registerXPathFunction(ctxt._o, "foo", None, foo) 2533res = ctxt.xpathEval("foo(1)") 2534if res != 2: 2535 print "xpath extension failure" 2536doc.freeDoc() 2537ctxt.xpathFreeContext()</pre> 2538 2539<p>Note how the extension function is registered with the context (but that 2540part is not yet finalized, this may change slightly in the future).</p> 2541 2542<h3>tstxpath.py:</h3> 2543 2544<p>This test is similar to the previous one but shows how the extension 2545function can access the XPath evaluation context:</p> 2546<pre>def foo(ctx, x): 2547 global called 2548 2549 # 2550 # test that access to the XPath evaluation contexts 2551 # 2552 pctxt = libxml2.xpathParserContext(_obj=ctx) 2553 ctxt = pctxt.context() 2554 called = ctxt.function() 2555 return x + 1</pre> 2556 2557<p>All the interfaces around the XPath parser(or rather evaluation) context 2558are not finalized, but it should be sufficient to do contextual work at the 2559evaluation point.</p> 2560 2561<h3>Memory debugging:</h3> 2562 2563<p>last but not least, all tests starts with the following prologue:</p> 2564<pre>#memory debug specific 2565libxml2.debugMemory(1)</pre> 2566 2567<p>and ends with the following epilogue:</p> 2568<pre>#memory debug specific 2569libxml2.cleanupParser() 2570if libxml2.debugMemory(1) == 0: 2571 print "OK" 2572else: 2573 print "Memory leak %d bytes" % (libxml2.debugMemory(1)) 2574 libxml2.dumpMemory()</pre> 2575 2576<p>Those activate the memory debugging interface of libxml2 where all 2577allocated block in the library are tracked. The prologue then cleans up the 2578library state and checks that all allocated memory has been freed. If not it 2579calls dumpMemory() which saves that list in a <code>.memdump</code> file.</p> 2580 2581<h2><a name="architecture">libxml2 architecture</a></h2> 2582 2583<p>Libxml2 is made of multiple components; some of them are optional, and 2584most of the block interfaces are public. The main components are:</p> 2585<ul> 2586 <li>an Input/Output layer</li> 2587 <li>FTP and HTTP client layers (optional)</li> 2588 <li>an Internationalization layer managing the encodings support</li> 2589 <li>a URI module</li> 2590 <li>the XML parser and its basic SAX interface</li> 2591 <li>an HTML parser using the same SAX interface (optional)</li> 2592 <li>a SAX tree module to build an in-memory DOM representation</li> 2593 <li>a tree module to manipulate the DOM representation</li> 2594 <li>a validation module using the DOM representation (optional)</li> 2595 <li>an XPath module for global lookup in a DOM representation 2596 (optional)</li> 2597 <li>a debug module (optional)</li> 2598</ul> 2599 2600<p>Graphically this gives the following:</p> 2601 2602<p><img src="libxml.gif" alt="a graphical view of the various"></p> 2603 2604<p></p> 2605 2606<h2><a name="tree">The tree output</a></h2> 2607 2608<p>The parser returns a tree built during the document analysis. The value 2609returned is an <strong>xmlDocPtr</strong> (i.e., a pointer to an 2610<strong>xmlDoc</strong> structure). This structure contains information such 2611as the file name, the document type, and a <strong>children</strong> pointer 2612which is the root of the document (or more exactly the first child under the 2613root which is the document). The tree is made of <strong>xmlNode</strong>s, 2614chained in double-linked lists of siblings and with a children<->parent 2615relationship. An xmlNode can also carry properties (a chain of xmlAttr 2616structures). An attribute may have a value which is a list of TEXT or 2617ENTITY_REF nodes.</p> 2618 2619<p>Here is an example (erroneous with respect to the XML spec since there 2620should be only one ELEMENT under the root):</p> 2621 2622<p><img src="structure.gif" alt=" structure.gif "></p> 2623 2624<p>In the source package there is a small program (not installed by default) 2625called <strong>xmllint</strong> which parses XML files given as argument and 2626prints them back as parsed. This is useful for detecting errors both in XML 2627code and in the XML parser itself. It has an option <strong>--debug</strong> 2628which prints the actual in-memory structure of the document; here is the 2629result with the <a href="#example">example</a> given before:</p> 2630<pre>DOCUMENT 2631version=1.0 2632standalone=true 2633 ELEMENT EXAMPLE 2634 ATTRIBUTE prop1 2635 TEXT 2636 content=gnome is great 2637 ATTRIBUTE prop2 2638 ENTITY_REF 2639 TEXT 2640 content= linux too 2641 ELEMENT head 2642 ELEMENT title 2643 TEXT 2644 content=Welcome to Gnome 2645 ELEMENT chapter 2646 ELEMENT title 2647 TEXT 2648 content=The Linux adventure 2649 ELEMENT p 2650 TEXT 2651 content=bla bla bla ... 2652 ELEMENT image 2653 ATTRIBUTE href 2654 TEXT 2655 content=linus.gif 2656 ELEMENT p 2657 TEXT 2658 content=...</pre> 2659 2660<p>This should be useful for learning the internal representation model.</p> 2661 2662<h2><a name="interface">The SAX interface</a></h2> 2663 2664<p>Sometimes the DOM tree output is just too large to fit reasonably into 2665memory. In that case (and if you don't expect to save back the XML document 2666loaded using libxml), it's better to use the SAX interface of libxml. SAX is 2667a <strong>callback-based interface</strong> to the parser. Before parsing, 2668the application layer registers a customized set of callbacks which are 2669called by the library as it progresses through the XML input.</p> 2670 2671<p>To get more detailed step-by-step guidance on using the SAX interface of 2672libxml, see the <a 2673href="http://www.daa.com.au/~james/gnome/xml-sax/xml-sax.html">nice 2674documentation</a>.written by <a href="mailto:james@daa.com.au">James 2675Henstridge</a>.</p> 2676 2677<p>You can debug the SAX behaviour by using the <strong>testSAX</strong> 2678program located in the gnome-xml module (it's usually not shipped in the 2679binary packages of libxml, but you can find it in the tar source 2680distribution). Here is the sequence of callbacks that would be reported by 2681testSAX when parsing the example XML document shown earlier:</p> 2682<pre>SAX.setDocumentLocator() 2683SAX.startDocument() 2684SAX.getEntity(amp) 2685SAX.startElement(EXAMPLE, prop1='gnome is great', prop2='&amp; linux too') 2686SAX.characters( , 3) 2687SAX.startElement(head) 2688SAX.characters( , 4) 2689SAX.startElement(title) 2690SAX.characters(Welcome to Gnome, 16) 2691SAX.endElement(title) 2692SAX.characters( , 3) 2693SAX.endElement(head) 2694SAX.characters( , 3) 2695SAX.startElement(chapter) 2696SAX.characters( , 4) 2697SAX.startElement(title) 2698SAX.characters(The Linux adventure, 19) 2699SAX.endElement(title) 2700SAX.characters( , 4) 2701SAX.startElement(p) 2702SAX.characters(bla bla bla ..., 15) 2703SAX.endElement(p) 2704SAX.characters( , 4) 2705SAX.startElement(image, href='linus.gif') 2706SAX.endElement(image) 2707SAX.characters( , 4) 2708SAX.startElement(p) 2709SAX.characters(..., 3) 2710SAX.endElement(p) 2711SAX.characters( , 3) 2712SAX.endElement(chapter) 2713SAX.characters( , 1) 2714SAX.endElement(EXAMPLE) 2715SAX.endDocument()</pre> 2716 2717<p>Most of the other interfaces of libxml2 are based on the DOM tree-building 2718facility, so nearly everything up to the end of this document presupposes the 2719use of the standard DOM tree build. Note that the DOM tree itself is built by 2720a set of registered default callbacks, without internal specific 2721interface.</p> 2722 2723<h2><a name="Validation">Validation & DTDs</a></h2> 2724 2725<p>Table of Content:</p> 2726<ol> 2727 <li><a href="#General5">General overview</a></li> 2728 <li><a href="#definition">The definition</a></li> 2729 <li><a href="#Simple">Simple rules</a> 2730 <ol> 2731 <li><a href="#reference">How to reference a DTD from a document</a></li> 2732 <li><a href="#Declaring">Declaring elements</a></li> 2733 <li><a href="#Declaring1">Declaring attributes</a></li> 2734 </ol> 2735 </li> 2736 <li><a href="#Some">Some examples</a></li> 2737 <li><a href="#validate">How to validate</a></li> 2738 <li><a href="#Other">Other resources</a></li> 2739</ol> 2740 2741<h3><a name="General5">General overview</a></h3> 2742 2743<p>Well what is validation and what is a DTD ?</p> 2744 2745<p>DTD is the acronym for Document Type Definition. This is a description of 2746the content for a family of XML files. This is part of the XML 1.0 2747specification, and allows one to describe and verify that a given document 2748instance conforms to the set of rules detailing its structure and content.</p> 2749 2750<p>Validation is the process of checking a document against a DTD (more 2751generally against a set of construction rules).</p> 2752 2753<p>The validation process and building DTDs are the two most difficult parts 2754of the XML life cycle. Briefly a DTD defines all the possible elements to be 2755found within your document, what is the formal shape of your document tree 2756(by defining the allowed content of an element; either text, a regular 2757expression for the allowed list of children, or mixed content i.e. both text 2758and children). The DTD also defines the valid attributes for all elements and 2759the types of those attributes.</p> 2760 2761<h3><a name="definition1">The definition</a></h3> 2762 2763<p>The <a href="http://www.w3.org/TR/REC-xml">W3C XML Recommendation</a> (<a 2764href="http://www.xml.com/axml/axml.html">Tim Bray's annotated version of 2765Rev1</a>):</p> 2766<ul> 2767 <li><a href="http://www.w3.org/TR/REC-xml#elemdecls">Declaring 2768 elements</a></li> 2769 <li><a href="http://www.w3.org/TR/REC-xml#attdecls">Declaring 2770 attributes</a></li> 2771</ul> 2772 2773<p>(unfortunately) all this is inherited from the SGML world, the syntax is 2774ancient...</p> 2775 2776<h3><a name="Simple1">Simple rules</a></h3> 2777 2778<p>Writing DTDs can be done in many ways. The rules to build them if you need 2779something permanent or something which can evolve over time can be radically 2780different. Really complex DTDs like DocBook ones are flexible but quite 2781harder to design. I will just focus on DTDs for a formats with a fixed simple 2782structure. It is just a set of basic rules, and definitely not exhaustive nor 2783usable for complex DTD design.</p> 2784 2785<h4><a name="reference1">How to reference a DTD from a document</a>:</h4> 2786 2787<p>Assuming the top element of the document is <code>spec</code> and the dtd 2788is placed in the file <code>mydtd</code> in the subdirectory 2789<code>dtds</code> of the directory from where the document were loaded:</p> 2790 2791<p><code><!DOCTYPE spec SYSTEM "dtds/mydtd"></code></p> 2792 2793<p>Notes:</p> 2794<ul> 2795 <li>The system string is actually an URI-Reference (as defined in <a 2796 href="http://www.ietf.org/rfc/rfc2396.txt">RFC 2396</a>) so you can use a 2797 full URL string indicating the location of your DTD on the Web. This is a 2798 really good thing to do if you want others to validate your document.</li> 2799 <li>It is also possible to associate a <code>PUBLIC</code> identifier (a 2800 magic string) so that the DTD is looked up in catalogs on the client side 2801 without having to locate it on the web.</li> 2802 <li>A DTD contains a set of element and attribute declarations, but they 2803 don't define what the root of the document should be. This is explicitly 2804 told to the parser/validator as the first element of the 2805 <code>DOCTYPE</code> declaration.</li> 2806</ul> 2807 2808<h4><a name="Declaring2">Declaring elements</a>:</h4> 2809 2810<p>The following declares an element <code>spec</code>:</p> 2811 2812<p><code><!ELEMENT spec (front, body, back?)></code></p> 2813 2814<p>It also expresses that the spec element contains one <code>front</code>, 2815one <code>body</code> and one optional <code>back</code> children elements in 2816this order. The declaration of one element of the structure and its content 2817are done in a single declaration. Similarly the following declares 2818<code>div1</code> elements:</p> 2819 2820<p><code><!ELEMENT div1 (head, (p | list | note)*, div2?)></code></p> 2821 2822<p>which means div1 contains one <code>head</code> then a series of optional 2823<code>p</code>, <code>list</code>s and <code>note</code>s and then an 2824optional <code>div2</code>. And last but not least an element can contain 2825text:</p> 2826 2827<p><code><!ELEMENT b (#PCDATA)></code></p> 2828 2829<p><code>b</code> contains text or being of mixed content (text and elements 2830in no particular order):</p> 2831 2832<p><code><!ELEMENT p (#PCDATA|a|ul|b|i|em)*></code></p> 2833 2834<p><code>p </code>can contain text or <code>a</code>, <code>ul</code>, 2835<code>b</code>, <code>i </code>or <code>em</code> elements in no particular 2836order.</p> 2837 2838<h4><a name="Declaring1">Declaring attributes</a>:</h4> 2839 2840<p>Again the attributes declaration includes their content definition:</p> 2841 2842<p><code><!ATTLIST termdef name CDATA #IMPLIED></code></p> 2843 2844<p>means that the element <code>termdef</code> can have a <code>name</code> 2845attribute containing text (<code>CDATA</code>) and which is optional 2846(<code>#IMPLIED</code>). The attribute value can also be defined within a 2847set:</p> 2848 2849<p><code><!ATTLIST list type (bullets|ordered|glossary) 2850"ordered"></code></p> 2851 2852<p>means <code>list</code> element have a <code>type</code> attribute with 3 2853allowed values "bullets", "ordered" or "glossary" and which default to 2854"ordered" if the attribute is not explicitly specified.</p> 2855 2856<p>The content type of an attribute can be text (<code>CDATA</code>), 2857anchor/reference/references 2858(<code>ID</code>/<code>IDREF</code>/<code>IDREFS</code>), entity(ies) 2859(<code>ENTITY</code>/<code>ENTITIES</code>) or name(s) 2860(<code>NMTOKEN</code>/<code>NMTOKENS</code>). The following defines that a 2861<code>chapter</code> element can have an optional <code>id</code> attribute 2862of type <code>ID</code>, usable for reference from attribute of type 2863IDREF:</p> 2864 2865<p><code><!ATTLIST chapter id ID #IMPLIED></code></p> 2866 2867<p>The last value of an attribute definition can be <code>#REQUIRED 2868</code>meaning that the attribute has to be given, <code>#IMPLIED</code> 2869meaning that it is optional, or the default value (possibly prefixed by 2870<code>#FIXED</code> if it is the only allowed).</p> 2871 2872<p>Notes:</p> 2873<ul> 2874 <li>Usually the attributes pertaining to a given element are declared in a 2875 single expression, but it is just a convention adopted by a lot of DTD 2876 writers: 2877 <pre><!ATTLIST termdef 2878 id ID #REQUIRED 2879 name CDATA #IMPLIED></pre> 2880 <p>The previous construct defines both <code>id</code> and 2881 <code>name</code> attributes for the element <code>termdef</code>.</p> 2882 </li> 2883</ul> 2884 2885<h3><a name="Some1">Some examples</a></h3> 2886 2887<p>The directory <code>test/valid/dtds/</code> in the libxml2 distribution 2888contains some complex DTD examples. The example in the file 2889<code>test/valid/dia.xml</code> shows an XML file where the simple DTD is 2890directly included within the document.</p> 2891 2892<h3><a name="validate1">How to validate</a></h3> 2893 2894<p>The simplest way is to use the xmllint program included with libxml. The 2895<code>--valid</code> option turns-on validation of the files given as input. 2896For example the following validates a copy of the first revision of the XML 28971.0 specification:</p> 2898 2899<p><code>xmllint --valid --noout test/valid/REC-xml-19980210.xml</code></p> 2900 2901<p>the -- noout is used to disable output of the resulting tree.</p> 2902 2903<p>The <code>--dtdvalid dtd</code> allows validation of the document(s) 2904against a given DTD.</p> 2905 2906<p>Libxml2 exports an API to handle DTDs and validation, check the <a 2907href="http://xmlsoft.org/html/libxml-valid.html">associated 2908description</a>.</p> 2909 2910<h3><a name="Other1">Other resources</a></h3> 2911 2912<p>DTDs are as old as SGML. So there may be a number of examples on-line, I 2913will just list one for now, others pointers welcome:</p> 2914<ul> 2915 <li><a href="http://www.xml101.com:8081/dtd/">XML-101 DTD</a></li> 2916</ul> 2917 2918<p>I suggest looking at the examples found under test/valid/dtd and any of 2919the large number of books available on XML. The dia example in test/valid 2920should be both simple and complete enough to allow you to build your own.</p> 2921 2922<p></p> 2923 2924<h2><a name="Memory">Memory Management</a></h2> 2925 2926<p>Table of Content:</p> 2927<ol> 2928 <li><a href="#General3">General overview</a></li> 2929 <li><a href="#setting">Setting libxml2 set of memory routines</a></li> 2930 <li><a href="#cleanup">Cleaning up after parsing</a></li> 2931 <li><a href="#Debugging">Debugging routines</a></li> 2932 <li><a href="#General4">General memory requirements</a></li> 2933</ol> 2934 2935<h3><a name="General3">General overview</a></h3> 2936 2937<p>The module <code><a 2938href="http://xmlsoft.org/html/libxml-xmlmemory.html">xmlmemory.h</a></code> 2939provides the interfaces to the libxml2 memory system:</p> 2940<ul> 2941 <li>libxml2 does not use the libc memory allocator directly but xmlFree(), 2942 xmlMalloc() and xmlRealloc()</li> 2943 <li>those routines can be reallocated to a specific set of routine, by 2944 default the libc ones i.e. free(), malloc() and realloc()</li> 2945 <li>the xmlmemory.c module includes a set of debugging routine</li> 2946</ul> 2947 2948<h3><a name="setting">Setting libxml2 set of memory routines</a></h3> 2949 2950<p>It is sometimes useful to not use the default memory allocator, either for 2951debugging, analysis or to implement a specific behaviour on memory management 2952(like on embedded systems). Two function calls are available to do so:</p> 2953<ul> 2954 <li><a href="http://xmlsoft.org/html/libxml-xmlmemory.html">xmlMemGet 2955 ()</a> which return the current set of functions in use by the parser</li> 2956 <li><a 2957 href="http://xmlsoft.org/html/libxml-xmlmemory.html">xmlMemSetup()</a> 2958 which allow to set up a new set of memory allocation functions</li> 2959</ul> 2960 2961<p>Of course a call to xmlMemSetup() should probably be done before calling 2962any other libxml2 routines (unless you are sure your allocations routines are 2963compatibles).</p> 2964 2965<h3><a name="cleanup">Cleaning up after parsing</a></h3> 2966 2967<p>Libxml2 is not stateless, there is a few set of memory structures needing 2968allocation before the parser is fully functional (some encoding structures 2969for example). This also mean that once parsing is finished there is a tiny 2970amount of memory (a few hundred bytes) which can be recollected if you don't 2971reuse the parser immediately:</p> 2972<ul> 2973 <li><a href="http://xmlsoft.org/html/libxml-parser.html">xmlCleanupParser 2974 ()</a> is a centralized routine to free the parsing states. Note that it 2975 won't deallocate any produced tree if any (use the xmlFreeDoc() and 2976 related routines for this).</li> 2977 <li><a href="http://xmlsoft.org/html/libxml-parser.html">xmlInitParser 2978 ()</a> is the dual routine allowing to preallocate the parsing state 2979 which can be useful for example to avoid initialization reentrancy 2980 problems when using libxml2 in multithreaded applications</li> 2981</ul> 2982 2983<p>Generally xmlCleanupParser() is safe, if needed the state will be rebuild 2984at the next invocation of parser routines, but be careful of the consequences 2985in multithreaded applications.</p> 2986 2987<h3><a name="Debugging">Debugging routines</a></h3> 2988 2989<p>When configured using --with-mem-debug flag (off by default), libxml2 uses 2990a set of memory allocation debugging routines keeping track of all allocated 2991blocks and the location in the code where the routine was called. A couple of 2992other debugging routines allow to dump the memory allocated infos to a file 2993or call a specific routine when a given block number is allocated:</p> 2994<ul> 2995 <li><a 2996 href="http://xmlsoft.org/html/libxml-xmlmemory.html">xmlMallocLoc()</a> 2997 <a 2998 href="http://xmlsoft.org/html/libxml-xmlmemory.html">xmlReallocLoc()</a> 2999 and <a 3000 href="http://xmlsoft.org/html/libxml-xmlmemory.html">xmlMemStrdupLoc()</a> 3001 are the memory debugging replacement allocation routines</li> 3002 <li><a href="http://xmlsoft.org/html/libxml-xmlmemory.html">xmlMemoryDump 3003 ()</a> dumps all the informations about the allocated memory block lefts 3004 in the <code>.memdump</code> file</li> 3005</ul> 3006 3007<p>When developing libxml2 memory debug is enabled, the tests programs call 3008xmlMemoryDump () and the "make test" regression tests will check for any 3009memory leak during the full regression test sequence, this helps a lot 3010ensuring that libxml2 does not leak memory and bullet proof memory 3011allocations use (some libc implementations are known to be far too permissive 3012resulting in major portability problems!).</p> 3013 3014<p>If the .memdump reports a leak, it displays the allocation function and 3015also tries to give some informations about the content and structure of the 3016allocated blocks left. This is sufficient in most cases to find the culprit, 3017but not always. Assuming the allocation problem is reproducible, it is 3018possible to find more easily:</p> 3019<ol> 3020 <li>write down the block number xxxx not allocated</li> 3021 <li>export the environment variable XML_MEM_BREAKPOINT=xxxx , the easiest 3022 when using GDB is to simply give the command 3023 <p><code>set environment XML_MEM_BREAKPOINT xxxx</code></p> 3024 <p>before running the program.</p> 3025 </li> 3026 <li>run the program under a debugger and set a breakpoint on 3027 xmlMallocBreakpoint() a specific function called when this precise block 3028 is allocated</li> 3029 <li>when the breakpoint is reached you can then do a fine analysis of the 3030 allocation an step to see the condition resulting in the missing 3031 deallocation.</li> 3032</ol> 3033 3034<p>I used to use a commercial tool to debug libxml2 memory problems but after 3035noticing that it was not detecting memory leaks that simple mechanism was 3036used and proved extremely efficient until now. Lately I have also used <a 3037href="http://developer.kde.org/~sewardj/">valgrind</a> with quite some 3038success, it is tied to the i386 architecture since it works by emulating the 3039processor and instruction set, it is slow but extremely efficient, i.e. it 3040spot memory usage errors in a very precise way.</p> 3041 3042<h3><a name="General4">General memory requirements</a></h3> 3043 3044<p>How much libxml2 memory require ? It's hard to tell in average it depends 3045of a number of things:</p> 3046<ul> 3047 <li>the parser itself should work in a fixed amount of memory, except for 3048 information maintained about the stacks of names and entities locations. 3049 The I/O and encoding handlers will probably account for a few KBytes. 3050 This is true for both the XML and HTML parser (though the HTML parser 3051 need more state).</li> 3052 <li>If you are generating the DOM tree then memory requirements will grow 3053 nearly linear with the size of the data. In general for a balanced 3054 textual document the internal memory requirement is about 4 times the 3055 size of the UTF8 serialization of this document (example the XML-1.0 3056 recommendation is a bit more of 150KBytes and takes 650KBytes of main 3057 memory when parsed). Validation will add a amount of memory required for 3058 maintaining the external Dtd state which should be linear with the 3059 complexity of the content model defined by the Dtd</li> 3060 <li>If you need to work with fixed memory requirements or don't need the 3061 full DOM tree then using the <a href="xmlreader.html">xmlReader 3062 interface</a> is probably the best way to proceed, it still allows to 3063 validate or operate on subset of the tree if needed.</li> 3064 <li>If you don't care about the advanced features of libxml2 like 3065 validation, DOM, XPath or XPointer, don't use entities, need to work with 3066 fixed memory requirements, and try to get the fastest parsing possible 3067 then the SAX interface should be used, but it has known restrictions.</li> 3068</ul> 3069 3070<p></p> 3071 3072<h2><a name="Encodings">Encodings support</a></h2> 3073 3074<p>Table of Content:</p> 3075<ol> 3076 <li><a href="encoding.html#What">What does internationalization support 3077 mean ?</a></li> 3078 <li><a href="encoding.html#internal">The internal encoding, how and 3079 why</a></li> 3080 <li><a href="encoding.html#implemente">How is it implemented ?</a></li> 3081 <li><a href="encoding.html#Default">Default supported encodings</a></li> 3082 <li><a href="encoding.html#extend">How to extend the existing 3083 support</a></li> 3084</ol> 3085 3086<h3><a name="What">What does internationalization support mean ?</a></h3> 3087 3088<p>If you are not really familiar with Internationalization (usual shortcut 3089is I18N) , Unicode, characters and glyphs, I suggest you read a <a 3090href="http://www.tbray.org/ongoing/When/200x/2003/04/06/Unicode">presentation</a> 3091by Tim Bray on Unicode and why you should care about it.</p> 3092 3093<p>XML was designed from the start to allow the support of any character set 3094by using Unicode. Any conformant XML parser has to support the UTF-8 and 3095UTF-16 default encodings which can both express the full unicode ranges. UTF8 3096is a variable length encoding whose greatest points are to reuse the same 3097encoding for ASCII and to save space for Western encodings, but it is a bit 3098more complex to handle in practice. UTF-16 use 2 bytes per character (and 3099sometimes combines two pairs), it makes implementation easier, but looks a 3100bit overkill for Western languages encoding. Moreover the XML specification 3101allows the document to be encoded in other encodings at the condition that 3102they are clearly labeled as such. For example the following is a wellformed 3103XML document encoded in ISO-8859-1 and using accentuated letters that we 3104French like for both markup and content:</p> 3105<pre><?xml version="1.0" encoding="ISO-8859-1"?> 3106<tr�s>l�</tr�s></pre> 3107 3108<p>Having internationalization support in libxml2 means the following:</p> 3109<ul> 3110 <li>the document is properly parsed</li> 3111 <li>informations about it's encoding are saved</li> 3112 <li>it can be modified</li> 3113 <li>it can be saved in its original encoding</li> 3114 <li>it can also be saved in another encoding supported by libxml2 (for 3115 example straight UTF8 or even an ASCII form)</li> 3116</ul> 3117 3118<p>Another very important point is that the whole libxml2 API, with the 3119exception of a few routines to read with a specific encoding or save to a 3120specific encoding, is completely agnostic about the original encoding of the 3121document.</p> 3122 3123<p>It should be noted too that the HTML parser embedded in libxml2 now obey 3124the same rules too, the following document will be (as of 2.2.2) handled in 3125an internationalized fashion by libxml2 too:</p> 3126<pre><!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN" 3127 "http://www.w3.org/TR/REC-html40/loose.dtd"> 3128<html lang="fr"> 3129<head> 3130 <META HTTP-EQUIV="Content-Type" CONTENT="text/html; charset=ISO-8859-1"> 3131</head> 3132<body> 3133<p>W3C cr�e des standards pour le Web.</body> 3134</html></pre> 3135 3136<h3><a name="internal">The internal encoding, how and why</a></h3> 3137 3138<p>One of the core decisions was to force all documents to be converted to a 3139default internal encoding, and that encoding to be UTF-8, here are the 3140rationales for those choices:</p> 3141<ul> 3142 <li>keeping the native encoding in the internal form would force the libxml 3143 users (or the code associated) to be fully aware of the encoding of the 3144 original document, for examples when adding a text node to a document, 3145 the content would have to be provided in the document encoding, i.e. the 3146 client code would have to check it before hand, make sure it's conformant 3147 to the encoding, etc ... Very hard in practice, though in some specific 3148 cases this may make sense.</li> 3149 <li>the second decision was which encoding. From the XML spec only UTF8 and 3150 UTF16 really makes sense as being the two only encodings for which there 3151 is mandatory support. UCS-4 (32 bits fixed size encoding) could be 3152 considered an intelligent choice too since it's a direct Unicode mapping 3153 support. I selected UTF-8 on the basis of efficiency and compatibility 3154 with surrounding software: 3155 <ul> 3156 <li>UTF-8 while a bit more complex to convert from/to (i.e. slightly 3157 more costly to import and export CPU wise) is also far more compact 3158 than UTF-16 (and UCS-4) for a majority of the documents I see it used 3159 for right now (RPM RDF catalogs, advogato data, various configuration 3160 file formats, etc.) and the key point for today's computer 3161 architecture is efficient uses of caches. If one nearly double the 3162 memory requirement to store the same amount of data, this will trash 3163 caches (main memory/external caches/internal caches) and my take is 3164 that this harms the system far more than the CPU requirements needed 3165 for the conversion to UTF-8</li> 3166 <li>Most of libxml2 version 1 users were using it with straight ASCII 3167 most of the time, doing the conversion with an internal encoding 3168 requiring all their code to be rewritten was a serious show-stopper 3169 for using UTF-16 or UCS-4.</li> 3170 <li>UTF-8 is being used as the de-facto internal encoding standard for 3171 related code like the <a href="http://www.pango.org/">pango</a> 3172 upcoming Gnome text widget, and a lot of Unix code (yet another place 3173 where Unix programmer base takes a different approach from Microsoft 3174 - they are using UTF-16)</li> 3175 </ul> 3176 </li> 3177</ul> 3178 3179<p>What does this mean in practice for the libxml2 user:</p> 3180<ul> 3181 <li>xmlChar, the libxml2 data type is a byte, those bytes must be assembled 3182 as UTF-8 valid strings. The proper way to terminate an xmlChar * string 3183 is simply to append 0 byte, as usual.</li> 3184 <li>One just need to make sure that when using chars outside the ASCII set, 3185 the values has been properly converted to UTF-8</li> 3186</ul> 3187 3188<h3><a name="implemente">How is it implemented ?</a></h3> 3189 3190<p>Let's describe how all this works within libxml, basically the I18N 3191(internationalization) support get triggered only during I/O operation, i.e. 3192when reading a document or saving one. Let's look first at the reading 3193sequence:</p> 3194<ol> 3195 <li>when a document is processed, we usually don't know the encoding, a 3196 simple heuristic allows to detect UTF-16 and UCS-4 from encodings where 3197 the ASCII range (0-0x7F) maps with ASCII</li> 3198 <li>the xml declaration if available is parsed, including the encoding 3199 declaration. At that point, if the autodetected encoding is different 3200 from the one declared a call to xmlSwitchEncoding() is issued.</li> 3201 <li>If there is no encoding declaration, then the input has to be in either 3202 UTF-8 or UTF-16, if it is not then at some point when processing the 3203 input, the converter/checker of UTF-8 form will raise an encoding error. 3204 You may end-up with a garbled document, or no document at all ! Example: 3205 <pre>~/XML -> /xmllint err.xml 3206err.xml:1: error: Input is not proper UTF-8, indicate encoding ! 3207<tr�s>l�</tr�s> 3208 ^ 3209err.xml:1: error: Bytes: 0xE8 0x73 0x3E 0x6C 3210<tr�s>l�</tr�s> 3211 ^</pre> 3212 </li> 3213 <li>xmlSwitchEncoding() does an encoding name lookup, canonicalize it, and 3214 then search the default registered encoding converters for that encoding. 3215 If it's not within the default set and iconv() support has been compiled 3216 it, it will ask iconv for such an encoder. If this fails then the parser 3217 will report an error and stops processing: 3218 <pre>~/XML -> /xmllint err2.xml 3219err2.xml:1: error: Unsupported encoding UnsupportedEnc 3220<?xml version="1.0" encoding="UnsupportedEnc"?> 3221 ^</pre> 3222 </li> 3223 <li>From that point the encoder processes progressively the input (it is 3224 plugged as a front-end to the I/O module) for that entity. It captures 3225 and converts on-the-fly the document to be parsed to UTF-8. The parser 3226 itself just does UTF-8 checking of this input and process it 3227 transparently. The only difference is that the encoding information has 3228 been added to the parsing context (more precisely to the input 3229 corresponding to this entity).</li> 3230 <li>The result (when using DOM) is an internal form completely in UTF-8 3231 with just an encoding information on the document node.</li> 3232</ol> 3233 3234<p>Ok then what happens when saving the document (assuming you 3235collected/built an xmlDoc DOM like structure) ? It depends on the function 3236called, xmlSaveFile() will just try to save in the original encoding, while 3237xmlSaveFileTo() and xmlSaveFileEnc() can optionally save to a given 3238encoding:</p> 3239<ol> 3240 <li>if no encoding is given, libxml2 will look for an encoding value 3241 associated to the document and if it exists will try to save to that 3242 encoding, 3243 <p>otherwise everything is written in the internal form, i.e. UTF-8</p> 3244 </li> 3245 <li>so if an encoding was specified, either at the API level or on the 3246 document, libxml2 will again canonicalize the encoding name, lookup for a 3247 converter in the registered set or through iconv. If not found the 3248 function will return an error code</li> 3249 <li>the converter is placed before the I/O buffer layer, as another kind of 3250 buffer, then libxml2 will simply push the UTF-8 serialization to through 3251 that buffer, which will then progressively be converted and pushed onto 3252 the I/O layer.</li> 3253 <li>It is possible that the converter code fails on some input, for example 3254 trying to push an UTF-8 encoded Chinese character through the UTF-8 to 3255 ISO-8859-1 converter won't work. Since the encoders are progressive they 3256 will just report the error and the number of bytes converted, at that 3257 point libxml2 will decode the offending character, remove it from the 3258 buffer and replace it with the associated charRef encoding &#123; and 3259 resume the conversion. This guarantees that any document will be saved 3260 without losses (except for markup names where this is not legal, this is 3261 a problem in the current version, in practice avoid using non-ascii 3262 characters for tag or attribute names). A special "ascii" encoding name 3263 is used to save documents to a pure ascii form can be used when 3264 portability is really crucial</li> 3265</ol> 3266 3267<p>Here are a few examples based on the same test document:</p> 3268<pre>~/XML -> /xmllint isolat1 3269<?xml version="1.0" encoding="ISO-8859-1"?> 3270<tr�s>l�</tr�s> 3271~/XML -> /xmllint --encode UTF-8 isolat1 3272<?xml version="1.0" encoding="UTF-8"?> 3273<très>l� �</très> 3274~/XML -> </pre> 3275 3276<p>The same processing is applied (and reuse most of the code) for HTML I18N 3277processing. Looking up and modifying the content encoding is a bit more 3278difficult since it is located in a <meta> tag under the <head>, 3279so a couple of functions htmlGetMetaEncoding() and htmlSetMetaEncoding() have 3280been provided. The parser also attempts to switch encoding on the fly when 3281detecting such a tag on input. Except for that the processing is the same 3282(and again reuses the same code).</p> 3283 3284<h3><a name="Default">Default supported encodings</a></h3> 3285 3286<p>libxml2 has a set of default converters for the following encodings 3287(located in encoding.c):</p> 3288<ol> 3289 <li>UTF-8 is supported by default (null handlers)</li> 3290 <li>UTF-16, both little and big endian</li> 3291 <li>ISO-Latin-1 (ISO-8859-1) covering most western languages</li> 3292 <li>ASCII, useful mostly for saving</li> 3293 <li>HTML, a specific handler for the conversion of UTF-8 to ASCII with HTML 3294 predefined entities like &copy; for the Copyright sign.</li> 3295</ol> 3296 3297<p>More over when compiled on an Unix platform with iconv support the full 3298set of encodings supported by iconv can be instantly be used by libxml. On a 3299linux machine with glibc-2.1 the list of supported encodings and aliases fill 33003 full pages, and include UCS-4, the full set of ISO-Latin encodings, and the 3301various Japanese ones.</p> 3302 3303<h4>Encoding aliases</h4> 3304 3305<p>From 2.2.3, libxml2 has support to register encoding names aliases. The 3306goal is to be able to parse document whose encoding is supported but where 3307the name differs (for example from the default set of names accepted by 3308iconv). The following functions allow to register and handle new aliases for 3309existing encodings. Once registered libxml2 will automatically lookup the 3310aliases when handling a document:</p> 3311<ul> 3312 <li>int xmlAddEncodingAlias(const char *name, const char *alias);</li> 3313 <li>int xmlDelEncodingAlias(const char *alias);</li> 3314 <li>const char * xmlGetEncodingAlias(const char *alias);</li> 3315 <li>void xmlCleanupEncodingAliases(void);</li> 3316</ul> 3317 3318<h3><a name="extend">How to extend the existing support</a></h3> 3319 3320<p>Well adding support for new encoding, or overriding one of the encoders 3321(assuming it is buggy) should not be hard, just write input and output 3322conversion routines to/from UTF-8, and register them using 3323xmlNewCharEncodingHandler(name, xxxToUTF8, UTF8Toxxx), and they will be 3324called automatically if the parser(s) encounter such an encoding name 3325(register it uppercase, this will help). The description of the encoders, 3326their arguments and expected return values are described in the encoding.h 3327header.</p> 3328 3329<p>A quick note on the topic of subverting the parser to use a different 3330internal encoding than UTF-8, in some case people will absolutely want to 3331keep the internal encoding different, I think it's still possible (but the 3332encoding must be compliant with ASCII on the same subrange) though I didn't 3333tried it. The key is to override the default conversion routines (by 3334registering null encoders/decoders for your charsets), and bypass the UTF-8 3335checking of the parser by setting the parser context charset 3336(ctxt->charset) to something different than XML_CHAR_ENCODING_UTF8, but 3337there is no guarantee that this will work. You may also have some troubles 3338saving back.</p> 3339 3340<p>Basically proper I18N support is important, this requires at least 3341libxml-2.0.0, but a lot of features and corrections are really available only 3342starting 2.2.</p> 3343 3344<h2><a name="IO">I/O Interfaces</a></h2> 3345 3346<p>Table of Content:</p> 3347<ol> 3348 <li><a href="#General1">General overview</a></li> 3349 <li><a href="#basic">The basic buffer type</a></li> 3350 <li><a href="#Input">Input I/O handlers</a></li> 3351 <li><a href="#Output">Output I/O handlers</a></li> 3352 <li><a href="#entities">The entities loader</a></li> 3353 <li><a href="#Example2">Example of customized I/O</a></li> 3354</ol> 3355 3356<h3><a name="General1">General overview</a></h3> 3357 3358<p>The module <code><a 3359href="http://xmlsoft.org/html/libxml-xmlio.html">xmlIO.h</a></code> provides 3360the interfaces to the libxml2 I/O system. This consists of 4 main parts:</p> 3361<ul> 3362 <li>Entities loader, this is a routine which tries to fetch the entities 3363 (files) based on their PUBLIC and SYSTEM identifiers. The default loader 3364 don't look at the public identifier since libxml2 do not maintain a 3365 catalog. You can redefine you own entity loader by using 3366 <code>xmlGetExternalEntityLoader()</code> and 3367 <code>xmlSetExternalEntityLoader()</code>. <a href="#entities">Check the 3368 example</a>.</li> 3369 <li>Input I/O buffers which are a commodity structure used by the parser(s) 3370 input layer to handle fetching the informations to feed the parser. This 3371 provides buffering and is also a placeholder where the encoding 3372 converters to UTF8 are piggy-backed.</li> 3373 <li>Output I/O buffers are similar to the Input ones and fulfill similar 3374 task but when generating a serialization from a tree.</li> 3375 <li>A mechanism to register sets of I/O callbacks and associate them with 3376 specific naming schemes like the protocol part of the URIs. 3377 <p>This affect the default I/O operations and allows to use specific I/O 3378 handlers for certain names.</p> 3379 </li> 3380</ul> 3381 3382<p>The general mechanism used when loading http://rpmfind.net/xml.html for 3383example in the HTML parser is the following:</p> 3384<ol> 3385 <li>The default entity loader calls <code>xmlNewInputFromFile()</code> with 3386 the parsing context and the URI string.</li> 3387 <li>the URI string is checked against the existing registered handlers 3388 using their match() callback function, if the HTTP module was compiled 3389 in, it is registered and its match() function will succeeds</li> 3390 <li>the open() function of the handler is called and if successful will 3391 return an I/O Input buffer</li> 3392 <li>the parser will the start reading from this buffer and progressively 3393 fetch information from the resource, calling the read() function of the 3394 handler until the resource is exhausted</li> 3395 <li>if an encoding change is detected it will be installed on the input 3396 buffer, providing buffering and efficient use of the conversion 3397 routines</li> 3398 <li>once the parser has finished, the close() function of the handler is 3399 called once and the Input buffer and associated resources are 3400 deallocated.</li> 3401</ol> 3402 3403<p>The user defined callbacks are checked first to allow overriding of the 3404default libxml2 I/O routines.</p> 3405 3406<h3><a name="basic">The basic buffer type</a></h3> 3407 3408<p>All the buffer manipulation handling is done using the 3409<code>xmlBuffer</code> type define in <code><a 3410href="http://xmlsoft.org/html/libxml-tree.html">tree.h</a> </code>which is a 3411resizable memory buffer. The buffer allocation strategy can be selected to be 3412either best-fit or use an exponential doubling one (CPU vs. memory use 3413trade-off). The values are <code>XML_BUFFER_ALLOC_EXACT</code> and 3414<code>XML_BUFFER_ALLOC_DOUBLEIT</code>, and can be set individually or on a 3415system wide basis using <code>xmlBufferSetAllocationScheme()</code>. A number 3416of functions allows to manipulate buffers with names starting with the 3417<code>xmlBuffer...</code> prefix.</p> 3418 3419<h3><a name="Input">Input I/O handlers</a></h3> 3420 3421<p>An Input I/O handler is a simple structure 3422<code>xmlParserInputBuffer</code> containing a context associated to the 3423resource (file descriptor, or pointer to a protocol handler), the read() and 3424close() callbacks to use and an xmlBuffer. And extra xmlBuffer and a charset 3425encoding handler are also present to support charset conversion when 3426needed.</p> 3427 3428<h3><a name="Output">Output I/O handlers</a></h3> 3429 3430<p>An Output handler <code>xmlOutputBuffer</code> is completely similar to an 3431Input one except the callbacks are write() and close().</p> 3432 3433<h3><a name="entities">The entities loader</a></h3> 3434 3435<p>The entity loader resolves requests for new entities and create inputs for 3436the parser. Creating an input from a filename or an URI string is done 3437through the xmlNewInputFromFile() routine. The default entity loader do not 3438handle the PUBLIC identifier associated with an entity (if any). So it just 3439calls xmlNewInputFromFile() with the SYSTEM identifier (which is mandatory in 3440XML).</p> 3441 3442<p>If you want to hook up a catalog mechanism then you simply need to 3443override the default entity loader, here is an example:</p> 3444<pre>#include <libxml/xmlIO.h> 3445 3446xmlExternalEntityLoader defaultLoader = NULL; 3447 3448xmlParserInputPtr 3449xmlMyExternalEntityLoader(const char *URL, const char *ID, 3450 xmlParserCtxtPtr ctxt) { 3451 xmlParserInputPtr ret; 3452 const char *fileID = NULL; 3453 /* lookup for the fileID depending on ID */ 3454 3455 ret = xmlNewInputFromFile(ctxt, fileID); 3456 if (ret != NULL) 3457 return(ret); 3458 if (defaultLoader != NULL) 3459 ret = defaultLoader(URL, ID, ctxt); 3460 return(ret); 3461} 3462 3463int main(..) { 3464 ... 3465 3466 /* 3467 * Install our own entity loader 3468 */ 3469 defaultLoader = xmlGetExternalEntityLoader(); 3470 xmlSetExternalEntityLoader(xmlMyExternalEntityLoader); 3471 3472 ... 3473}</pre> 3474 3475<h3><a name="Example2">Example of customized I/O</a></h3> 3476 3477<p>This example come from <a href="http://xmlsoft.org/messages/0708.html">a 3478real use case</a>, xmlDocDump() closes the FILE * passed by the application 3479and this was a problem. The <a 3480href="http://xmlsoft.org/messages/0711.html">solution</a> was to redefine a 3481new output handler with the closing call deactivated:</p> 3482<ol> 3483 <li>First define a new I/O output allocator where the output don't close 3484 the file: 3485 <pre>xmlOutputBufferPtr 3486xmlOutputBufferCreateOwn(FILE *file, xmlCharEncodingHandlerPtr encoder) { 3487����xmlOutputBufferPtr ret; 3488���� 3489����if (xmlOutputCallbackInitialized == 0) 3490��������xmlRegisterDefaultOutputCallbacks(); 3491 3492����if (file == NULL) return(NULL); 3493����ret = xmlAllocOutputBuffer(encoder); 3494����if (ret != NULL) { 3495��������ret->context = file; 3496��������ret->writecallback = xmlFileWrite; 3497��������ret->closecallback = NULL; /* No close callback */ 3498����} 3499����return(ret); 3500} </pre> 3501 </li> 3502 <li>And then use it to save the document: 3503 <pre>FILE *f; 3504xmlOutputBufferPtr output; 3505xmlDocPtr doc; 3506int res; 3507 3508f = ... 3509doc = .... 3510 3511output = xmlOutputBufferCreateOwn(f, NULL); 3512res = xmlSaveFileTo(output, doc, NULL); 3513 </pre> 3514 </li> 3515</ol> 3516 3517<h2><a name="Catalog">Catalog support</a></h2> 3518 3519<p>Table of Content:</p> 3520<ol> 3521 <li><a href="General2">General overview</a></li> 3522 <li><a href="#definition">The definition</a></li> 3523 <li><a href="#Simple">Using catalogs</a></li> 3524 <li><a href="#Some">Some examples</a></li> 3525 <li><a href="#reference">How to tune catalog usage</a></li> 3526 <li><a href="#validate">How to debug catalog processing</a></li> 3527 <li><a href="#Declaring">How to create and maintain catalogs</a></li> 3528 <li><a href="#implemento">The implementor corner quick review of the 3529 API</a></li> 3530 <li><a href="#Other">Other resources</a></li> 3531</ol> 3532 3533<h3><a name="General2">General overview</a></h3> 3534 3535<p>What is a catalog? Basically it's a lookup mechanism used when an entity 3536(a file or a remote resource) references another entity. The catalog lookup 3537is inserted between the moment the reference is recognized by the software 3538(XML parser, stylesheet processing, or even images referenced for inclusion 3539in a rendering) and the time where loading that resource is actually 3540started.</p> 3541 3542<p>It is basically used for 3 things:</p> 3543<ul> 3544 <li>mapping from "logical" names, the public identifiers and a more 3545 concrete name usable for download (and URI). For example it can associate 3546 the logical name 3547 <p>"-//OASIS//DTD DocBook XML V4.1.2//EN"</p> 3548 <p>of the DocBook 4.1.2 XML DTD with the actual URL where it can be 3549 downloaded</p> 3550 <p>http://www.oasis-open.org/docbook/xml/4.1.2/docbookx.dtd</p> 3551 </li> 3552 <li>remapping from a given URL to another one, like an HTTP indirection 3553 saying that 3554 <p>"http://www.oasis-open.org/committes/tr.xsl"</p> 3555 <p>should really be looked at</p> 3556 <p>"http://www.oasis-open.org/committes/entity/stylesheets/base/tr.xsl"</p> 3557 </li> 3558 <li>providing a local cache mechanism allowing to load the entities 3559 associated to public identifiers or remote resources, this is a really 3560 important feature for any significant deployment of XML or SGML since it 3561 allows to avoid the aleas and delays associated to fetching remote 3562 resources.</li> 3563</ul> 3564 3565<h3><a name="definition">The definitions</a></h3> 3566 3567<p>Libxml, as of 2.4.3 implements 2 kind of catalogs:</p> 3568<ul> 3569 <li>the older SGML catalogs, the official spec is SGML Open Technical 3570 Resolution TR9401:1997, but is better understood by reading <a 3571 href="http://www.jclark.com/sp/catalog.htm">the SP Catalog page</a> from 3572 James Clark. This is relatively old and not the preferred mode of 3573 operation of libxml.</li> 3574 <li><a href="http://www.oasis-open.org/committees/entity/spec.html">XML 3575 Catalogs</a> is far more flexible, more recent, uses an XML syntax and 3576 should scale quite better. This is the default option of libxml.</li> 3577</ul> 3578 3579<p></p> 3580 3581<h3><a name="Simple">Using catalog</a></h3> 3582 3583<p>In a normal environment libxml2 will by default check the presence of a 3584catalog in /etc/xml/catalog, and assuming it has been correctly populated, 3585the processing is completely transparent to the document user. To take a 3586concrete example, suppose you are authoring a DocBook document, this one 3587starts with the following DOCTYPE definition:</p> 3588<pre><?xml version='1.0'?> 3589<!DOCTYPE book PUBLIC "-//Norman Walsh//DTD DocBk XML V3.1.4//EN" 3590 "http://nwalsh.com/docbook/xml/3.1.4/db3xml.dtd"></pre> 3591 3592<p>When validating the document with libxml, the catalog will be 3593automatically consulted to lookup the public identifier "-//Norman Walsh//DTD 3594DocBk XML V3.1.4//EN" and the system identifier 3595"http://nwalsh.com/docbook/xml/3.1.4/db3xml.dtd", and if these entities have 3596been installed on your system and the catalogs actually point to them, libxml 3597will fetch them from the local disk.</p> 3598 3599<p style="font-size: 10pt"><strong>Note</strong>: Really don't use this 3600DOCTYPE example it's a really old version, but is fine as an example.</p> 3601 3602<p>Libxml2 will check the catalog each time that it is requested to load an 3603entity, this includes DTD, external parsed entities, stylesheets, etc ... If 3604your system is correctly configured all the authoring phase and processing 3605should use only local files, even if your document stays portable because it 3606uses the canonical public and system ID, referencing the remote document.</p> 3607 3608<h3><a name="Some">Some examples:</a></h3> 3609 3610<p>Here is a couple of fragments from XML Catalogs used in libxml2 early 3611regression tests in <code>test/catalogs</code> :</p> 3612<pre><?xml version="1.0"?> 3613<!DOCTYPE catalog PUBLIC 3614 "-//OASIS//DTD Entity Resolution XML Catalog V1.0//EN" 3615 "http://www.oasis-open.org/committees/entity/release/1.0/catalog.dtd"> 3616<catalog xmlns="urn:oasis:names:tc:entity:xmlns:xml:catalog"> 3617 <public publicId="-//OASIS//DTD DocBook XML V4.1.2//EN" 3618 uri="http://www.oasis-open.org/docbook/xml/4.1.2/docbookx.dtd"/> 3619...</pre> 3620 3621<p>This is the beginning of a catalog for DocBook 4.1.2, XML Catalogs are 3622written in XML, there is a specific namespace for catalog elements 3623"urn:oasis:names:tc:entity:xmlns:xml:catalog". The first entry in this 3624catalog is a <code>public</code> mapping it allows to associate a Public 3625Identifier with an URI.</p> 3626<pre>... 3627 <rewriteSystem systemIdStartString="http://www.oasis-open.org/docbook/" 3628 rewritePrefix="file:///usr/share/xml/docbook/"/> 3629...</pre> 3630 3631<p>A <code>rewriteSystem</code> is a very powerful instruction, it says that 3632any URI starting with a given prefix should be looked at another URI 3633constructed by replacing the prefix with an new one. In effect this acts like 3634a cache system for a full area of the Web. In practice it is extremely useful 3635with a file prefix if you have installed a copy of those resources on your 3636local system.</p> 3637<pre>... 3638<delegatePublic publicIdStartString="-//OASIS//DTD XML Catalog //" 3639 catalog="file:///usr/share/xml/docbook.xml"/> 3640<delegatePublic publicIdStartString="-//OASIS//ENTITIES DocBook XML" 3641 catalog="file:///usr/share/xml/docbook.xml"/> 3642<delegatePublic publicIdStartString="-//OASIS//DTD DocBook XML" 3643 catalog="file:///usr/share/xml/docbook.xml"/> 3644<delegateSystem systemIdStartString="http://www.oasis-open.org/docbook/" 3645 catalog="file:///usr/share/xml/docbook.xml"/> 3646<delegateURI uriStartString="http://www.oasis-open.org/docbook/" 3647 catalog="file:///usr/share/xml/docbook.xml"/> 3648...</pre> 3649 3650<p>Delegation is the core features which allows to build a tree of catalogs, 3651easier to maintain than a single catalog, based on Public Identifier, System 3652Identifier or URI prefixes it instructs the catalog software to look up 3653entries in another resource. This feature allow to build hierarchies of 3654catalogs, the set of entries presented should be sufficient to redirect the 3655resolution of all DocBook references to the specific catalog in 3656<code>/usr/share/xml/docbook.xml</code> this one in turn could delegate all 3657references for DocBook 4.2.1 to a specific catalog installed at the same time 3658as the DocBook resources on the local machine.</p> 3659 3660<h3><a name="reference">How to tune catalog usage:</a></h3> 3661 3662<p>The user can change the default catalog behaviour by redirecting queries 3663to its own set of catalogs, this can be done by setting the 3664<code>XML_CATALOG_FILES</code> environment variable to a list of catalogs, an 3665empty one should deactivate loading the default <code>/etc/xml/catalog</code> 3666default catalog</p> 3667 3668<h3><a name="validate">How to debug catalog processing:</a></h3> 3669 3670<p>Setting up the <code>XML_DEBUG_CATALOG</code> environment variable will 3671make libxml2 output debugging informations for each catalog operations, for 3672example:</p> 3673<pre>orchis:~/XML -> xmllint --memory --noout test/ent2 3674warning: failed to load external entity "title.xml" 3675orchis:~/XML -> export XML_DEBUG_CATALOG= 3676orchis:~/XML -> xmllint --memory --noout test/ent2 3677Failed to parse catalog /etc/xml/catalog 3678Failed to parse catalog /etc/xml/catalog 3679warning: failed to load external entity "title.xml" 3680Catalogs cleanup 3681orchis:~/XML -> </pre> 3682 3683<p>The test/ent2 references an entity, running the parser from memory makes 3684the base URI unavailable and the the "title.xml" entity cannot be loaded. 3685Setting up the debug environment variable allows to detect that an attempt is 3686made to load the <code>/etc/xml/catalog</code> but since it's not present the 3687resolution fails.</p> 3688 3689<p>But the most advanced way to debug XML catalog processing is to use the 3690<strong>xmlcatalog</strong> command shipped with libxml2, it allows to load 3691catalogs and make resolution queries to see what is going on. This is also 3692used for the regression tests:</p> 3693<pre>orchis:~/XML -> /xmlcatalog test/catalogs/docbook.xml \ 3694 "-//OASIS//DTD DocBook XML V4.1.2//EN" 3695http://www.oasis-open.org/docbook/xml/4.1.2/docbookx.dtd 3696orchis:~/XML -> </pre> 3697 3698<p>For debugging what is going on, adding one -v flags increase the verbosity 3699level to indicate the processing done (adding a second flag also indicate 3700what elements are recognized at parsing):</p> 3701<pre>orchis:~/XML -> /xmlcatalog -v test/catalogs/docbook.xml \ 3702 "-//OASIS//DTD DocBook XML V4.1.2//EN" 3703Parsing catalog test/catalogs/docbook.xml's content 3704Found public match -//OASIS//DTD DocBook XML V4.1.2//EN 3705http://www.oasis-open.org/docbook/xml/4.1.2/docbookx.dtd 3706Catalogs cleanup 3707orchis:~/XML -> </pre> 3708 3709<p>A shell interface is also available to debug and process multiple queries 3710(and for regression tests):</p> 3711<pre>orchis:~/XML -> /xmlcatalog -shell test/catalogs/docbook.xml \ 3712 "-//OASIS//DTD DocBook XML V4.1.2//EN" 3713> help 3714Commands available: 3715public PublicID: make a PUBLIC identifier lookup 3716system SystemID: make a SYSTEM identifier lookup 3717resolve PublicID SystemID: do a full resolver lookup 3718add 'type' 'orig' 'replace' : add an entry 3719del 'values' : remove values 3720dump: print the current catalog state 3721debug: increase the verbosity level 3722quiet: decrease the verbosity level 3723exit: quit the shell 3724> public "-//OASIS//DTD DocBook XML V4.1.2//EN" 3725http://www.oasis-open.org/docbook/xml/4.1.2/docbookx.dtd 3726> quit 3727orchis:~/XML -> </pre> 3728 3729<p>This should be sufficient for most debugging purpose, this was actually 3730used heavily to debug the XML Catalog implementation itself.</p> 3731 3732<h3><a name="Declaring">How to create and maintain</a> catalogs:</h3> 3733 3734<p>Basically XML Catalogs are XML files, you can either use XML tools to 3735manage them or use <strong>xmlcatalog</strong> for this. The basic step is 3736to create a catalog the -create option provide this facility:</p> 3737<pre>orchis:~/XML -> /xmlcatalog --create tst.xml 3738<?xml version="1.0"?> 3739<!DOCTYPE catalog PUBLIC "-//OASIS//DTD Entity Resolution XML Catalog V1.0//EN" 3740 "http://www.oasis-open.org/committees/entity/release/1.0/catalog.dtd"> 3741<catalog xmlns="urn:oasis:names:tc:entity:xmlns:xml:catalog"/> 3742orchis:~/XML -> </pre> 3743 3744<p>By default xmlcatalog does not overwrite the original catalog and save the 3745result on the standard output, this can be overridden using the -noout 3746option. The <code>-add</code> command allows to add entries in the 3747catalog:</p> 3748<pre>orchis:~/XML -> /xmlcatalog --noout --create --add "public" \ 3749 "-//OASIS//DTD DocBook XML V4.1.2//EN" \ 3750 http://www.oasis-open.org/docbook/xml/4.1.2/docbookx.dtd tst.xml 3751orchis:~/XML -> cat tst.xml 3752<?xml version="1.0"?> 3753<!DOCTYPE catalog PUBLIC "-//OASIS//DTD Entity Resolution XML Catalog V1.0//EN" \ 3754 "http://www.oasis-open.org/committees/entity/release/1.0/catalog.dtd"> 3755<catalog xmlns="urn:oasis:names:tc:entity:xmlns:xml:catalog"> 3756<public publicId="-//OASIS//DTD DocBook XML V4.1.2//EN" 3757 uri="http://www.oasis-open.org/docbook/xml/4.1.2/docbookx.dtd"/> 3758</catalog> 3759orchis:~/XML -> </pre> 3760 3761<p>The <code>-add</code> option will always take 3 parameters even if some of 3762the XML Catalog constructs (like nextCatalog) will have only a single 3763argument, just pass a third empty string, it will be ignored.</p> 3764 3765<p>Similarly the <code>-del</code> option remove matching entries from the 3766catalog:</p> 3767<pre>orchis:~/XML -> /xmlcatalog --del \ 3768 "http://www.oasis-open.org/docbook/xml/4.1.2/docbookx.dtd" tst.xml 3769<?xml version="1.0"?> 3770<!DOCTYPE catalog PUBLIC "-//OASIS//DTD Entity Resolution XML Catalog V1.0//EN" 3771 "http://www.oasis-open.org/committees/entity/release/1.0/catalog.dtd"> 3772<catalog xmlns="urn:oasis:names:tc:entity:xmlns:xml:catalog"/> 3773orchis:~/XML -> </pre> 3774 3775<p>The catalog is now empty. Note that the matching of <code>-del</code> is 3776exact and would have worked in a similar fashion with the Public ID 3777string.</p> 3778 3779<p>This is rudimentary but should be sufficient to manage a not too complex 3780catalog tree of resources.</p> 3781 3782<h3><a name="implemento">The implementor corner quick review of the 3783API:</a></h3> 3784 3785<p>First, and like for every other module of libxml, there is an 3786automatically generated <a href="html/libxml-catalog.html">API page for 3787catalog support</a>.</p> 3788 3789<p>The header for the catalog interfaces should be included as:</p> 3790<pre>#include <libxml/catalog.h></pre> 3791 3792<p>The API is voluntarily kept very simple. First it is not obvious that 3793applications really need access to it since it is the default behaviour of 3794libxml2 (Note: it is possible to completely override libxml2 default catalog 3795by using <a href="html/libxml-parser.html">xmlSetExternalEntityLoader</a> to 3796plug an application specific resolver).</p> 3797 3798<p>Basically libxml2 support 2 catalog lists:</p> 3799<ul> 3800 <li>the default one, global shared by all the application</li> 3801 <li>a per-document catalog, this one is built if the document uses the 3802 <code>oasis-xml-catalog</code> PIs to specify its own catalog list, it is 3803 associated to the parser context and destroyed when the parsing context 3804 is destroyed.</li> 3805</ul> 3806 3807<p>the document one will be used first if it exists.</p> 3808 3809<h4>Initialization routines:</h4> 3810 3811<p>xmlInitializeCatalog(), xmlLoadCatalog() and xmlLoadCatalogs() should be 3812used at startup to initialize the catalog, if the catalog should be 3813initialized with specific values xmlLoadCatalog() or xmlLoadCatalogs() 3814should be called before xmlInitializeCatalog() which would otherwise do a 3815default initialization first.</p> 3816 3817<p>The xmlCatalogAddLocal() call is used by the parser to grow the document 3818own catalog list if needed.</p> 3819 3820<h4>Preferences setup:</h4> 3821 3822<p>The XML Catalog spec requires the possibility to select default 3823preferences between public and system delegation, 3824xmlCatalogSetDefaultPrefer() allows this, xmlCatalogSetDefaults() and 3825xmlCatalogGetDefaults() allow to control if XML Catalogs resolution should 3826be forbidden, allowed for global catalog, for document catalog or both, the 3827default is to allow both.</p> 3828 3829<p>And of course xmlCatalogSetDebug() allows to generate debug messages 3830(through the xmlGenericError() mechanism).</p> 3831 3832<h4>Querying routines:</h4> 3833 3834<p>xmlCatalogResolve(), xmlCatalogResolveSystem(), xmlCatalogResolvePublic() 3835and xmlCatalogResolveURI() are relatively explicit if you read the XML 3836Catalog specification they correspond to section 7 algorithms, they should 3837also work if you have loaded an SGML catalog with a simplified semantic.</p> 3838 3839<p>xmlCatalogLocalResolve() and xmlCatalogLocalResolveURI() are the same but 3840operate on the document catalog list</p> 3841 3842<h4>Cleanup and Miscellaneous:</h4> 3843 3844<p>xmlCatalogCleanup() free-up the global catalog, xmlCatalogFreeLocal() is 3845the per-document equivalent.</p> 3846 3847<p>xmlCatalogAdd() and xmlCatalogRemove() are used to dynamically modify the 3848first catalog in the global list, and xmlCatalogDump() allows to dump a 3849catalog state, those routines are primarily designed for xmlcatalog, I'm not 3850sure that exposing more complex interfaces (like navigation ones) would be 3851really useful.</p> 3852 3853<p>The xmlParseCatalogFile() is a function used to load XML Catalog files, 3854it's similar as xmlParseFile() except it bypass all catalog lookups, it's 3855provided because this functionality may be useful for client tools.</p> 3856 3857<h4>threaded environments:</h4> 3858 3859<p>Since the catalog tree is built progressively, some care has been taken to 3860try to avoid troubles in multithreaded environments. The code is now thread 3861safe assuming that the libxml2 library has been compiled with threads 3862support.</p> 3863 3864<p></p> 3865 3866<h3><a name="Other">Other resources</a></h3> 3867 3868<p>The XML Catalog specification is relatively recent so there isn't much 3869literature to point at:</p> 3870<ul> 3871 <li>You can find a good rant from Norm Walsh about <a 3872 href="http://www.arbortext.com/Think_Tank/XML_Resources/Issue_Three/issue_three.html">the 3873 need for catalogs</a>, it provides a lot of context informations even if 3874 I don't agree with everything presented. Norm also wrote a more recent 3875 article <a 3876 href="http://wwws.sun.com/software/xml/developers/resolver/article/">XML 3877 entities and URI resolvers</a> describing them.</li> 3878 <li>An <a href="http://home.ccil.org/~cowan/XML/XCatalog.html">old XML 3879 catalog proposal</a> from John Cowan</li> 3880 <li>The <a href="http://www.rddl.org/">Resource Directory Description 3881 Language</a> (RDDL) another catalog system but more oriented toward 3882 providing metadata for XML namespaces.</li> 3883 <li>the page from the OASIS Technical <a 3884 href="http://www.oasis-open.org/committees/entity/">Committee on Entity 3885 Resolution</a> who maintains XML Catalog, you will find pointers to the 3886 specification update, some background and pointers to others tools 3887 providing XML Catalog support</li> 3888 <li>There is a <a href="buildDocBookCatalog">shell script</a> to generate 3889 XML Catalogs for DocBook 4.1.2 . If it can write to the /etc/xml/ 3890 directory, it will set-up /etc/xml/catalog and /etc/xml/docbook based on 3891 the resources found on the system. Otherwise it will just create 3892 ~/xmlcatalog and ~/dbkxmlcatalog and doing: 3893 <p><code>export XML_CATALOG_FILES=$HOME/xmlcatalog</code></p> 3894 <p>should allow to process DocBook documentations without requiring 3895 network accesses for the DTD or stylesheets</p> 3896 </li> 3897 <li>I have uploaded <a href="ftp://xmlsoft.org/test/dbk412catalog.tar.gz">a 3898 small tarball</a> containing XML Catalogs for DocBook 4.1.2 which seems 3899 to work fine for me too</li> 3900 <li>The <a href="http://www.xmlsoft.org/xmlcatalog_man.html">xmlcatalog 3901 manual page</a></li> 3902</ul> 3903 3904<p>If you have suggestions for corrections or additions, simply contact 3905me:</p> 3906 3907<h2><a name="library">The parser interfaces</a></h2> 3908 3909<p>This section is directly intended to help programmers getting bootstrapped 3910using the XML tollkit from the C language. It is not intended to be 3911extensive. I hope the automatically generated documents will provide the 3912completeness required, but as a separate set of documents. The interfaces of 3913the XML parser are by principle low level, Those interested in a higher level 3914API should <a href="#DOM">look at DOM</a>.</p> 3915 3916<p>The <a href="html/libxml-parser.html">parser interfaces for XML</a> are 3917separated from the <a href="html/libxml-htmlparser.html">HTML parser 3918interfaces</a>. Let's have a look at how the XML parser can be called:</p> 3919 3920<h3><a name="Invoking">Invoking the parser : the pull method</a></h3> 3921 3922<p>Usually, the first thing to do is to read an XML input. The parser accepts 3923documents either from in-memory strings or from files. The functions are 3924defined in "parser.h":</p> 3925<dl> 3926 <dt><code>xmlDocPtr xmlParseMemory(char *buffer, int size);</code></dt> 3927 <dd><p>Parse a null-terminated string containing the document.</p> 3928 </dd> 3929</dl> 3930<dl> 3931 <dt><code>xmlDocPtr xmlParseFile(const char *filename);</code></dt> 3932 <dd><p>Parse an XML document contained in a (possibly compressed) 3933 file.</p> 3934 </dd> 3935</dl> 3936 3937<p>The parser returns a pointer to the document structure (or NULL in case of 3938failure).</p> 3939 3940<h3 id="Invoking1">Invoking the parser: the push method</h3> 3941 3942<p>In order for the application to keep the control when the document is 3943being fetched (which is common for GUI based programs) libxml2 provides a 3944push interface, too, as of version 1.8.3. Here are the interface 3945functions:</p> 3946<pre>xmlParserCtxtPtr xmlCreatePushParserCtxt(xmlSAXHandlerPtr sax, 3947 void *user_data, 3948 const char *chunk, 3949 int size, 3950 const char *filename); 3951int xmlParseChunk (xmlParserCtxtPtr ctxt, 3952 const char *chunk, 3953 int size, 3954 int terminate);</pre> 3955 3956<p>and here is a simple example showing how to use the interface:</p> 3957<pre> FILE *f; 3958 3959 f = fopen(filename, "r"); 3960 if (f != NULL) { 3961 int res, size = 1024; 3962 char chars[1024]; 3963 xmlParserCtxtPtr ctxt; 3964 3965 res = fread(chars, 1, 4, f); 3966 if (res > 0) { 3967 ctxt = xmlCreatePushParserCtxt(NULL, NULL, 3968 chars, res, filename); 3969 while ((res = fread(chars, 1, size, f)) > 0) { 3970 xmlParseChunk(ctxt, chars, res, 0); 3971 } 3972 xmlParseChunk(ctxt, chars, 0, 1); 3973 doc = ctxt->myDoc; 3974 xmlFreeParserCtxt(ctxt); 3975 } 3976 }</pre> 3977 3978<p>The HTML parser embedded into libxml2 also has a push interface; the 3979functions are just prefixed by "html" rather than "xml".</p> 3980 3981<h3 id="Invoking2">Invoking the parser: the SAX interface</h3> 3982 3983<p>The tree-building interface makes the parser memory-hungry, first loading 3984the document in memory and then building the tree itself. Reading a document 3985without building the tree is possible using the SAX interfaces (see SAX.h and 3986<a href="http://www.daa.com.au/~james/gnome/xml-sax/xml-sax.html">James 3987Henstridge's documentation</a>). Note also that the push interface can be 3988limited to SAX: just use the two first arguments of 3989<code>xmlCreatePushParserCtxt()</code>.</p> 3990 3991<h3><a name="Building">Building a tree from scratch</a></h3> 3992 3993<p>The other way to get an XML tree in memory is by building it. Basically 3994there is a set of functions dedicated to building new elements. (These are 3995also described in <libxml/tree.h>.) For example, here is a piece of 3996code that produces the XML document used in the previous examples:</p> 3997<pre> #include <libxml/tree.h> 3998 xmlDocPtr doc; 3999 xmlNodePtr tree, subtree; 4000 4001 doc = xmlNewDoc("1.0"); 4002 doc->children = xmlNewDocNode(doc, NULL, "EXAMPLE", NULL); 4003 xmlSetProp(doc->children, "prop1", "gnome is great"); 4004 xmlSetProp(doc->children, "prop2", "& linux too"); 4005 tree = xmlNewChild(doc->children, NULL, "head", NULL); 4006 subtree = xmlNewChild(tree, NULL, "title", "Welcome to Gnome"); 4007 tree = xmlNewChild(doc->children, NULL, "chapter", NULL); 4008 subtree = xmlNewChild(tree, NULL, "title", "The Linux adventure"); 4009 subtree = xmlNewChild(tree, NULL, "p", "bla bla bla ..."); 4010 subtree = xmlNewChild(tree, NULL, "image", NULL); 4011 xmlSetProp(subtree, "href", "linus.gif");</pre> 4012 4013<p>Not really rocket science ...</p> 4014 4015<h3><a name="Traversing">Traversing the tree</a></h3> 4016 4017<p>Basically by <a href="html/libxml-tree.html">including "tree.h"</a> your 4018code has access to the internal structure of all the elements of the tree. 4019The names should be somewhat simple like <strong>parent</strong>, 4020<strong>children</strong>, <strong>next</strong>, <strong>prev</strong>, 4021<strong>properties</strong>, etc... For example, still with the previous 4022example:</p> 4023<pre><code>doc->children->children->children</code></pre> 4024 4025<p>points to the title element,</p> 4026<pre>doc->children->children->next->children->children</pre> 4027 4028<p>points to the text node containing the chapter title "The Linux 4029adventure".</p> 4030 4031<p><strong>NOTE</strong>: XML allows <em>PI</em>s and <em>comments</em> to be 4032present before the document root, so <code>doc->children</code> may point 4033to an element which is not the document Root Element; a function 4034<code>xmlDocGetRootElement()</code> was added for this purpose.</p> 4035 4036<h3><a name="Modifying">Modifying the tree</a></h3> 4037 4038<p>Functions are provided for reading and writing the document content. Here 4039is an excerpt from the <a href="html/libxml-tree.html">tree API</a>:</p> 4040<dl> 4041 <dt><code>xmlAttrPtr xmlSetProp(xmlNodePtr node, const xmlChar *name, const 4042 xmlChar *value);</code></dt> 4043 <dd><p>This sets (or changes) an attribute carried by an ELEMENT node. 4044 The value can be NULL.</p> 4045 </dd> 4046</dl> 4047<dl> 4048 <dt><code>const xmlChar *xmlGetProp(xmlNodePtr node, const xmlChar 4049 *name);</code></dt> 4050 <dd><p>This function returns a pointer to new copy of the property 4051 content. Note that the user must deallocate the result.</p> 4052 </dd> 4053</dl> 4054 4055<p>Two functions are provided for reading and writing the text associated 4056with elements:</p> 4057<dl> 4058 <dt><code>xmlNodePtr xmlStringGetNodeList(xmlDocPtr doc, const xmlChar 4059 *value);</code></dt> 4060 <dd><p>This function takes an "external" string and converts it to one 4061 text node or possibly to a list of entity and text nodes. All 4062 non-predefined entity references like &Gnome; will be stored 4063 internally as entity nodes, hence the result of the function may not be 4064 a single node.</p> 4065 </dd> 4066</dl> 4067<dl> 4068 <dt><code>xmlChar *xmlNodeListGetString(xmlDocPtr doc, xmlNodePtr list, int 4069 inLine);</code></dt> 4070 <dd><p>This function is the inverse of 4071 <code>xmlStringGetNodeList()</code>. It generates a new string 4072 containing the content of the text and entity nodes. Note the extra 4073 argument inLine. If this argument is set to 1, the function will expand 4074 entity references. For example, instead of returning the &Gnome; 4075 XML encoding in the string, it will substitute it with its value (say, 4076 "GNU Network Object Model Environment").</p> 4077 </dd> 4078</dl> 4079 4080<h3><a name="Saving">Saving a tree</a></h3> 4081 4082<p>Basically 3 options are possible:</p> 4083<dl> 4084 <dt><code>void xmlDocDumpMemory(xmlDocPtr cur, xmlChar**mem, int 4085 *size);</code></dt> 4086 <dd><p>Returns a buffer into which the document has been saved.</p> 4087 </dd> 4088</dl> 4089<dl> 4090 <dt><code>extern void xmlDocDump(FILE *f, xmlDocPtr doc);</code></dt> 4091 <dd><p>Dumps a document to an open file descriptor.</p> 4092 </dd> 4093</dl> 4094<dl> 4095 <dt><code>int xmlSaveFile(const char *filename, xmlDocPtr cur);</code></dt> 4096 <dd><p>Saves the document to a file. In this case, the compression 4097 interface is triggered if it has been turned on.</p> 4098 </dd> 4099</dl> 4100 4101<h3><a name="Compressio">Compression</a></h3> 4102 4103<p>The library transparently handles compression when doing file-based 4104accesses. The level of compression on saves can be turned on either globally 4105or individually for one file:</p> 4106<dl> 4107 <dt><code>int xmlGetDocCompressMode (xmlDocPtr doc);</code></dt> 4108 <dd><p>Gets the document compression ratio (0-9).</p> 4109 </dd> 4110</dl> 4111<dl> 4112 <dt><code>void xmlSetDocCompressMode (xmlDocPtr doc, int mode);</code></dt> 4113 <dd><p>Sets the document compression ratio.</p> 4114 </dd> 4115</dl> 4116<dl> 4117 <dt><code>int xmlGetCompressMode(void);</code></dt> 4118 <dd><p>Gets the default compression ratio.</p> 4119 </dd> 4120</dl> 4121<dl> 4122 <dt><code>void xmlSetCompressMode(int mode);</code></dt> 4123 <dd><p>Sets the default compression ratio.</p> 4124 </dd> 4125</dl> 4126 4127<h2><a name="Entities">Entities or no entities</a></h2> 4128 4129<p>Entities in principle are similar to simple C macros. An entity defines an 4130abbreviation for a given string that you can reuse many times throughout the 4131content of your document. Entities are especially useful when a given string 4132may occur frequently within a document, or to confine the change needed to a 4133document to a restricted area in the internal subset of the document (at the 4134beginning). Example:</p> 4135<pre>1 <?xml version="1.0"?> 41362 <!DOCTYPE EXAMPLE SYSTEM "example.dtd" [ 41373 <!ENTITY xml "Extensible Markup Language"> 41384 ]> 41395 <EXAMPLE> 41406 &xml; 41417 </EXAMPLE></pre> 4142 4143<p>Line 3 declares the xml entity. Line 6 uses the xml entity, by prefixing 4144its name with '&' and following it by ';' without any spaces added. There 4145are 5 predefined entities in libxml2 allowing you to escape characters with 4146predefined meaning in some parts of the xml document content: 4147<strong>&lt;</strong> for the character '<', <strong>&gt;</strong> 4148for the character '>', <strong>&apos;</strong> for the character ''', 4149<strong>&quot;</strong> for the character '"', and 4150<strong>&amp;</strong> for the character '&'.</p> 4151 4152<p>One of the problems related to entities is that you may want the parser to 4153substitute an entity's content so that you can see the replacement text in 4154your application. Or you may prefer to keep entity references as such in the 4155content to be able to save the document back without losing this usually 4156precious information (if the user went through the pain of explicitly 4157defining entities, he may have a a rather negative attitude if you blindly 4158substitute them as saving time). The <a 4159href="html/libxml-parser.html#xmlSubstituteEntitiesDefault">xmlSubstituteEntitiesDefault()</a> 4160function allows you to check and change the behaviour, which is to not 4161substitute entities by default.</p> 4162 4163<p>Here is the DOM tree built by libxml2 for the previous document in the 4164default case:</p> 4165<pre>/gnome/src/gnome-xml -> /xmllint --debug test/ent1 4166DOCUMENT 4167version=1.0 4168 ELEMENT EXAMPLE 4169 TEXT 4170 content= 4171 ENTITY_REF 4172 INTERNAL_GENERAL_ENTITY xml 4173 content=Extensible Markup Language 4174 TEXT 4175 content=</pre> 4176 4177<p>And here is the result when substituting entities:</p> 4178<pre>/gnome/src/gnome-xml -> /tester --debug --noent test/ent1 4179DOCUMENT 4180version=1.0 4181 ELEMENT EXAMPLE 4182 TEXT 4183 content= Extensible Markup Language</pre> 4184 4185<p>So, entities or no entities? Basically, it depends on your use case. I 4186suggest that you keep the non-substituting default behaviour and avoid using 4187entities in your XML document or data if you are not willing to handle the 4188entity references elements in the DOM tree.</p> 4189 4190<p>Note that at save time libxml2 enforces the conversion of the predefined 4191entities where necessary to prevent well-formedness problems, and will also 4192transparently replace those with chars (i.e. it will not generate entity 4193reference elements in the DOM tree or call the reference() SAX callback when 4194finding them in the input).</p> 4195 4196<p><span style="background-color: #FF0000">WARNING</span>: handling entities 4197on top of the libxml2 SAX interface is difficult!!! If you plan to use 4198non-predefined entities in your documents, then the learning curve to handle 4199then using the SAX API may be long. If you plan to use complex documents, I 4200strongly suggest you consider using the DOM interface instead and let libxml 4201deal with the complexity rather than trying to do it yourself.</p> 4202 4203<h2><a name="Namespaces">Namespaces</a></h2> 4204 4205<p>The libxml2 library implements <a 4206href="http://www.w3.org/TR/REC-xml-names/">XML namespaces</a> support by 4207recognizing namespace constructs in the input, and does namespace lookup 4208automatically when building the DOM tree. A namespace declaration is 4209associated with an in-memory structure and all elements or attributes within 4210that namespace point to it. Hence testing the namespace is a simple and fast 4211equality operation at the user level.</p> 4212 4213<p>I suggest that people using libxml2 use a namespace, and declare it in the 4214root element of their document as the default namespace. Then they don't need 4215to use the prefix in the content but we will have a basis for future semantic 4216refinement and merging of data from different sources. This doesn't increase 4217the size of the XML output significantly, but significantly increases its 4218value in the long-term. Example:</p> 4219<pre><mydoc xmlns="http://mydoc.example.org/schemas/"> 4220 <elem1>...</elem1> 4221 <elem2>...</elem2> 4222</mydoc></pre> 4223 4224<p>The namespace value has to be an absolute URL, but the URL doesn't have to 4225point to any existing resource on the Web. It will bind all the element and 4226attributes with that URL. I suggest to use an URL within a domain you 4227control, and that the URL should contain some kind of version information if 4228possible. For example, <code>"http://www.gnome.org/gnumeric/1.0/"</code> is a 4229good namespace scheme.</p> 4230 4231<p>Then when you load a file, make sure that a namespace carrying the 4232version-independent prefix is installed on the root element of your document, 4233and if the version information don't match something you know, warn the user 4234and be liberal in what you accept as the input. Also do *not* try to base 4235namespace checking on the prefix value. <foo:text> may be exactly the 4236same as <bar:text> in another document. What really matters is the URI 4237associated with the element or the attribute, not the prefix string (which is 4238just a shortcut for the full URI). In libxml, element and attributes have an 4239<code>ns</code> field pointing to an xmlNs structure detailing the namespace 4240prefix and its URI.</p> 4241 4242<p>@@Interfaces@@</p> 4243<pre>xmlNodePtr node; 4244if(!strncmp(node->name,"mytag",5) 4245 && node->ns 4246 && !strcmp(node->ns->href,"http://www.mysite.com/myns/1.0")) { 4247 ... 4248}</pre> 4249 4250<p>Usually people object to using namespaces together with validity checking. 4251I will try to make sure that using namespaces won't break validity checking, 4252so even if you plan to use or currently are using validation I strongly 4253suggest adding namespaces to your document. A default namespace scheme 4254<code>xmlns="http://...."</code> should not break validity even on less 4255flexible parsers. Using namespaces to mix and differentiate content coming 4256from multiple DTDs will certainly break current validation schemes. To check 4257such documents one needs to use schema-validation, which is supported in 4258libxml2 as well. See <a href="http://www.relaxng.org/">relagx-ng</a> and <a 4259href="http://www.w3c.org/XML/Schema">w3c-schema</a>.</p> 4260 4261<h2><a name="Upgrading">Upgrading 1.x code</a></h2> 4262 4263<p>Incompatible changes:</p> 4264 4265<p>Version 2 of libxml2 is the first version introducing serious backward 4266incompatible changes. The main goals were:</p> 4267<ul> 4268 <li>a general cleanup. A number of mistakes inherited from the very early 4269 versions couldn't be changed due to compatibility constraints. Example 4270 the "childs" element in the nodes.</li> 4271 <li>Uniformization of the various nodes, at least for their header and link 4272 parts (doc, parent, children, prev, next), the goal is a simpler 4273 programming model and simplifying the task of the DOM implementors.</li> 4274 <li>better conformances to the XML specification, for example version 1.x 4275 had an heuristic to try to detect ignorable white spaces. As a result the 4276 SAX event generated were ignorableWhitespace() while the spec requires 4277 character() in that case. This also mean that a number of DOM node 4278 containing blank text may populate the DOM tree which were not present 4279 before.</li> 4280</ul> 4281 4282<h3>How to fix libxml-1.x code:</h3> 4283 4284<p>So client code of libxml designed to run with version 1.x may have to be 4285changed to compile against version 2.x of libxml. Here is a list of changes 4286that I have collected, they may not be sufficient, so in case you find other 4287change which are required, <a href="mailto:Daniel.Veillard@w3.org">drop me a 4288mail</a>:</p> 4289<ol> 4290 <li>The package name have changed from libxml to libxml2, the library name 4291 is now -lxml2 . There is a new xml2-config script which should be used to 4292 select the right parameters libxml2</li> 4293 <li>Node <strong>childs</strong> field has been renamed 4294 <strong>children</strong> so s/childs/children/g should be applied 4295 (probability of having "childs" anywhere else is close to 0+</li> 4296 <li>The document don't have anymore a <strong>root</strong> element it has 4297 been replaced by <strong>children</strong> and usually you will get a 4298 list of element here. For example a Dtd element for the internal subset 4299 and it's declaration may be found in that list, as well as processing 4300 instructions or comments found before or after the document root element. 4301 Use <strong>xmlDocGetRootElement(doc)</strong> to get the root element of 4302 a document. Alternatively if you are sure to not reference DTDs nor have 4303 PIs or comments before or after the root element 4304 s/->root/->children/g will probably do it.</li> 4305 <li>The white space issue, this one is more complex, unless special case of 4306 validating parsing, the line breaks and spaces usually used for indenting 4307 and formatting the document content becomes significant. So they are 4308 reported by SAX and if your using the DOM tree, corresponding nodes are 4309 generated. Too approach can be taken: 4310 <ol> 4311 <li>lazy one, use the compatibility call 4312 <strong>xmlKeepBlanksDefault(0)</strong> but be aware that you are 4313 relying on a special (and possibly broken) set of heuristics of 4314 libxml to detect ignorable blanks. Don't complain if it breaks or 4315 make your application not 100% clean w.r.t. to it's input.</li> 4316 <li>the Right Way: change you code to accept possibly insignificant 4317 blanks characters, or have your tree populated with weird blank text 4318 nodes. You can spot them using the commodity function 4319 <strong>xmlIsBlankNode(node)</strong> returning 1 for such blank 4320 nodes.</li> 4321 </ol> 4322 <p>Note also that with the new default the output functions don't add any 4323 extra indentation when saving a tree in order to be able to round trip 4324 (read and save) without inflating the document with extra formatting 4325 chars.</p> 4326 </li> 4327 <li>The include path has changed to $prefix/libxml/ and the includes 4328 themselves uses this new prefix in includes instructions... If you are 4329 using (as expected) the 4330 <pre>xml2-config --cflags</pre> 4331 <p>output to generate you compile commands this will probably work out of 4332 the box</p> 4333 </li> 4334 <li>xmlDetectCharEncoding takes an extra argument indicating the length in 4335 byte of the head of the document available for character detection.</li> 4336</ol> 4337 4338<h3>Ensuring both libxml-1.x and libxml-2.x compatibility</h3> 4339 4340<p>Two new version of libxml (1.8.11) and libxml2 (2.3.4) have been released 4341to allow smooth upgrade of existing libxml v1code while retaining 4342compatibility. They offers the following:</p> 4343<ol> 4344 <li>similar include naming, one should use 4345 <strong>#include<libxml/...></strong> in both cases.</li> 4346 <li>similar identifiers defined via macros for the child and root fields: 4347 respectively <strong>xmlChildrenNode</strong> and 4348 <strong>xmlRootNode</strong></li> 4349 <li>a new macro <strong>LIBXML_TEST_VERSION</strong> which should be 4350 inserted once in the client code</li> 4351</ol> 4352 4353<p>So the roadmap to upgrade your existing libxml applications is the 4354following:</p> 4355<ol> 4356 <li>install the libxml-1.8.8 (and libxml-devel-1.8.8) packages</li> 4357 <li>find all occurrences where the xmlDoc <strong>root</strong> field is 4358 used and change it to <strong>xmlRootNode</strong></li> 4359 <li>similarly find all occurrences where the xmlNode 4360 <strong>childs</strong> field is used and change it to 4361 <strong>xmlChildrenNode</strong></li> 4362 <li>add a <strong>LIBXML_TEST_VERSION</strong> macro somewhere in your 4363 <strong>main()</strong> or in the library init entry point</li> 4364 <li>Recompile, check compatibility, it should still work</li> 4365 <li>Change your configure script to look first for xml2-config and fall 4366 back using xml-config . Use the --cflags and --libs output of the command 4367 as the Include and Linking parameters needed to use libxml.</li> 4368 <li>install libxml2-2.3.x and libxml2-devel-2.3.x (libxml-1.8.y and 4369 libxml-devel-1.8.y can be kept simultaneously)</li> 4370 <li>remove your config.cache, relaunch your configuration mechanism, and 4371 recompile, if steps 2 and 3 were done right it should compile as-is</li> 4372 <li>Test that your application is still running correctly, if not this may 4373 be due to extra empty nodes due to formating spaces being kept in libxml2 4374 contrary to libxml1, in that case insert xmlKeepBlanksDefault(1) in your 4375 code before calling the parser (next to 4376 <strong>LIBXML_TEST_VERSION</strong> is a fine place).</li> 4377</ol> 4378 4379<p>Following those steps should work. It worked for some of my own code.</p> 4380 4381<p>Let me put some emphasis on the fact that there is far more changes from 4382libxml 1.x to 2.x than the ones you may have to patch for. The overall code 4383has been considerably cleaned up and the conformance to the XML specification 4384has been drastically improved too. Don't take those changes as an excuse to 4385not upgrade, it may cost a lot on the long term ...</p> 4386 4387<h2><a name="Thread">Thread safety</a></h2> 4388 4389<p>Starting with 2.4.7, libxml2 makes provisions to ensure that concurrent 4390threads can safely work in parallel parsing different documents. There is 4391however a couple of things to do to ensure it:</p> 4392<ul> 4393 <li>configure the library accordingly using the --with-threads options</li> 4394 <li>call xmlInitParser() in the "main" thread before using any of the 4395 libxml2 API (except possibly selecting a different memory allocator)</li> 4396</ul> 4397 4398<p>Note that the thread safety cannot be ensured for multiple threads sharing 4399the same document, the locking must be done at the application level, libxml 4400exports a basic mutex and reentrant mutexes API in <libxml/threads.h>. 4401The parts of the library checked for thread safety are:</p> 4402<ul> 4403 <li>concurrent loading</li> 4404 <li>file access resolution</li> 4405 <li>catalog access</li> 4406 <li>catalog building</li> 4407 <li>entities lookup/accesses</li> 4408 <li>validation</li> 4409 <li>global variables per-thread override</li> 4410 <li>memory handling</li> 4411</ul> 4412 4413<p>XPath is supposed to be thread safe now, but this wasn't tested 4414seriously.</p> 4415 4416<h2><a name="DOM"></a><a name="Principles">DOM Principles</a></h2> 4417 4418<p><a href="http://www.w3.org/DOM/">DOM</a> stands for the <em>Document 4419Object Model</em>; this is an API for accessing XML or HTML structured 4420documents. Native support for DOM in Gnome is on the way (module gnome-dom), 4421and will be based on gnome-xml. This will be a far cleaner interface to 4422manipulate XML files within Gnome since it won't expose the internal 4423structure.</p> 4424 4425<p>The current DOM implementation on top of libxml2 is the <a 4426href="http://cvs.gnome.org/lxr/source/gdome2/">gdome2 Gnome module</a>, this 4427is a full DOM interface, thanks to Paolo Casarini, check the <a 4428href="http://www.cs.unibo.it/~casarini/gdome2/">Gdome2 homepage</a> for more 4429informations.</p> 4430 4431<h2><a name="Example"></a><a name="real">A real example</a></h2> 4432 4433<p>Here is a real size example, where the actual content of the application 4434data is not kept in the DOM tree but uses internal structures. It is based on 4435a proposal to keep a database of jobs related to Gnome, with an XML based 4436storage structure. Here is an <a href="gjobs.xml">XML encoded jobs 4437base</a>:</p> 4438<pre><?xml version="1.0"?> 4439<gjob:Helping xmlns:gjob="http://www.gnome.org/some-location"> 4440 <gjob:Jobs> 4441 4442 <gjob:Job> 4443 <gjob:Project ID="3"/> 4444 <gjob:Application>GBackup</gjob:Application> 4445 <gjob:Category>Development</gjob:Category> 4446 4447 <gjob:Update> 4448 <gjob:Status>Open</gjob:Status> 4449 <gjob:Modified>Mon, 07 Jun 1999 20:27:45 -0400 MET DST</gjob:Modified> 4450 <gjob:Salary>USD 0.00</gjob:Salary> 4451 </gjob:Update> 4452 4453 <gjob:Developers> 4454 <gjob:Developer> 4455 </gjob:Developer> 4456 </gjob:Developers> 4457 4458 <gjob:Contact> 4459 <gjob:Person>Nathan Clemons</gjob:Person> 4460 <gjob:Email>nathan@windsofstorm.net</gjob:Email> 4461 <gjob:Company> 4462 </gjob:Company> 4463 <gjob:Organisation> 4464 </gjob:Organisation> 4465 <gjob:Webpage> 4466 </gjob:Webpage> 4467 <gjob:Snailmail> 4468 </gjob:Snailmail> 4469 <gjob:Phone> 4470 </gjob:Phone> 4471 </gjob:Contact> 4472 4473 <gjob:Requirements> 4474 The program should be released as free software, under the GPL. 4475 </gjob:Requirements> 4476 4477 <gjob:Skills> 4478 </gjob:Skills> 4479 4480 <gjob:Details> 4481 A GNOME based system that will allow a superuser to configure 4482 compressed and uncompressed files and/or file systems to be backed 4483 up with a supported media in the system. This should be able to 4484 perform via find commands generating a list of files that are passed 4485 to tar, dd, cpio, cp, gzip, etc., to be directed to the tape machine 4486 or via operations performed on the filesystem itself. Email 4487 notification and GUI status display very important. 4488 </gjob:Details> 4489 4490 </gjob:Job> 4491 4492 </gjob:Jobs> 4493</gjob:Helping></pre> 4494 4495<p>While loading the XML file into an internal DOM tree is a matter of 4496calling only a couple of functions, browsing the tree to gather the data and 4497generate the internal structures is harder, and more error prone.</p> 4498 4499<p>The suggested principle is to be tolerant with respect to the input 4500structure. For example, the ordering of the attributes is not significant, 4501the XML specification is clear about it. It's also usually a good idea not to 4502depend on the order of the children of a given node, unless it really makes 4503things harder. Here is some code to parse the information for a person:</p> 4504<pre>/* 4505 * A person record 4506 */ 4507typedef struct person { 4508 char *name; 4509 char *email; 4510 char *company; 4511 char *organisation; 4512 char *smail; 4513 char *webPage; 4514 char *phone; 4515} person, *personPtr; 4516 4517/* 4518 * And the code needed to parse it 4519 */ 4520personPtr parsePerson(xmlDocPtr doc, xmlNsPtr ns, xmlNodePtr cur) { 4521 personPtr ret = NULL; 4522 4523DEBUG("parsePerson\n"); 4524 /* 4525 * allocate the struct 4526 */ 4527 ret = (personPtr) malloc(sizeof(person)); 4528 if (ret == NULL) { 4529 fprintf(stderr,"out of memory\n"); 4530 return(NULL); 4531 } 4532 memset(ret, 0, sizeof(person)); 4533 4534 /* We don't care what the top level element name is */ 4535 cur = cur->xmlChildrenNode; 4536 while (cur != NULL) { 4537 if ((!strcmp(cur->name, "Person")) && (cur->ns == ns)) 4538 ret->name = xmlNodeListGetString(doc, cur->xmlChildrenNode, 1); 4539 if ((!strcmp(cur->name, "Email")) && (cur->ns == ns)) 4540 ret->email = xmlNodeListGetString(doc, cur->xmlChildrenNode, 1); 4541 cur = cur->next; 4542 } 4543 4544 return(ret); 4545}</pre> 4546 4547<p>Here are a couple of things to notice:</p> 4548<ul> 4549 <li>Usually a recursive parsing style is the more convenient one: XML data 4550 is by nature subject to repetitive constructs and usually exhibits highly 4551 structured patterns.</li> 4552 <li>The two arguments of type <em>xmlDocPtr</em> and <em>xmlNsPtr</em>, 4553 i.e. the pointer to the global XML document and the namespace reserved to 4554 the application. Document wide information are needed for example to 4555 decode entities and it's a good coding practice to define a namespace for 4556 your application set of data and test that the element and attributes 4557 you're analyzing actually pertains to your application space. This is 4558 done by a simple equality test (cur->ns == ns).</li> 4559 <li>To retrieve text and attributes value, you can use the function 4560 <em>xmlNodeListGetString</em> to gather all the text and entity reference 4561 nodes generated by the DOM output and produce an single text string.</li> 4562</ul> 4563 4564<p>Here is another piece of code used to parse another level of the 4565structure:</p> 4566<pre>#include <libxml/tree.h> 4567/* 4568 * a Description for a Job 4569 */ 4570typedef struct job { 4571 char *projectID; 4572 char *application; 4573 char *category; 4574 personPtr contact; 4575 int nbDevelopers; 4576 personPtr developers[100]; /* using dynamic alloc is left as an exercise */ 4577} job, *jobPtr; 4578 4579/* 4580 * And the code needed to parse it 4581 */ 4582jobPtr parseJob(xmlDocPtr doc, xmlNsPtr ns, xmlNodePtr cur) { 4583 jobPtr ret = NULL; 4584 4585DEBUG("parseJob\n"); 4586 /* 4587 * allocate the struct 4588 */ 4589 ret = (jobPtr) malloc(sizeof(job)); 4590 if (ret == NULL) { 4591 fprintf(stderr,"out of memory\n"); 4592 return(NULL); 4593 } 4594 memset(ret, 0, sizeof(job)); 4595 4596 /* We don't care what the top level element name is */ 4597 cur = cur->xmlChildrenNode; 4598 while (cur != NULL) { 4599 4600 if ((!strcmp(cur->name, "Project")) && (cur->ns == ns)) { 4601 ret->projectID = xmlGetProp(cur, "ID"); 4602 if (ret->projectID == NULL) { 4603 fprintf(stderr, "Project has no ID\n"); 4604 } 4605 } 4606 if ((!strcmp(cur->name, "Application")) && (cur->ns == ns)) 4607 ret->application = xmlNodeListGetString(doc, cur->xmlChildrenNode, 1); 4608 if ((!strcmp(cur->name, "Category")) && (cur->ns == ns)) 4609 ret->category = xmlNodeListGetString(doc, cur->xmlChildrenNode, 1); 4610 if ((!strcmp(cur->name, "Contact")) && (cur->ns == ns)) 4611 ret->contact = parsePerson(doc, ns, cur); 4612 cur = cur->next; 4613 } 4614 4615 return(ret); 4616}</pre> 4617 4618<p>Once you are used to it, writing this kind of code is quite simple, but 4619boring. Ultimately, it could be possible to write stubbers taking either C 4620data structure definitions, a set of XML examples or an XML DTD and produce 4621the code needed to import and export the content between C data and XML 4622storage. This is left as an exercise to the reader :-)</p> 4623 4624<p>Feel free to use <a href="example/gjobread.c">the code for the full C 4625parsing example</a> as a template, it is also available with Makefile in the 4626Gnome CVS base under gnome-xml/example</p> 4627 4628<h2><a name="Contributi">Contributions</a></h2> 4629<ul> 4630 <li>Bjorn Reese, William Brack and Thomas Broyer have provided a number of 4631 patches, Gary Pennington worked on the validation API, threading support 4632 and Solaris port.</li> 4633 <li>John Fleck helps maintaining the documentation and man pages.</li> 4634 <li><a href="mailto:igor@zlatkovic.com">Igor Zlatkovic</a> is now the 4635 maintainer of the Windows port, <a 4636 href="http://www.zlatkovic.com/projects/libxml/index.html">he provides 4637 binaries</a></li> 4638 <li><a href="mailto:Gary.Pennington@sun.com">Gary Pennington</a> provides 4639 <a href="http://garypennington.net/libxml2/">Solaris binaries</a></li> 4640 <li><a 4641 href="http://mail.gnome.org/archives/xml/2001-March/msg00014.html">Matt 4642 Sergeant</a> developed <a 4643 href="http://axkit.org/download/">XML::LibXSLT</a>, a Perl wrapper for 4644 libxml2/libxslt as part of the <a href="http://axkit.com/">AxKit XML 4645 application server</a></li> 4646 <li><a href="mailto:fnatter@gmx.net">Felix Natter</a> and <a 4647 href="mailto:geertk@ai.rug.nl">Geert Kloosterman</a> provide <a 4648 href="libxml-doc.el">an emacs module</a> to lookup libxml(2) functions 4649 documentation</li> 4650 <li><a href="mailto:sherwin@nlm.nih.gov">Ziying Sherwin</a> provided <a 4651 href="http://xmlsoft.org/messages/0488.html">man pages</a></li> 4652 <li>there is a module for <a 4653 href="http://acs-misc.sourceforge.net/nsxml.html">libxml/libxslt support 4654 in OpenNSD/AOLServer</a></li> 4655 <li><a href="mailto:dkuhlman@cutter.rexx.com">Dave Kuhlman</a> provided the 4656 first version of libxml/libxslt <a 4657 href="http://www.rexx.com/~dkuhlman">wrappers for Python</a></li> 4658 <li>Petr Kozelka provides <a 4659 href="http://sourceforge.net/projects/libxml2-pas">Pascal units to glue 4660 libxml2</a> with Kylix and Delphi and other Pascal compilers</li> 4661 <li><a href="mailto:aleksey@aleksey.com">Aleksey Sanin</a> implemented the 4662 <a href="http://www.w3.org/Signature/">XML Canonicalization and XML 4663 Digital Signature</a> <a 4664 href="http://www.aleksey.com/xmlsec/">implementations for libxml2</a></li> 4665 <li><a href="mailto:Steve.Ball@zveno.com">Steve Ball</a>, <a 4666 href="http://www.zveno.com/">Zveno</a> and contributors maintain <a 4667 href="http://tclxml.sourceforge.net/">tcl bindings for libxml2 and 4668 libxslt</a>, as well as <a 4669 href="http://tclxml.sf.net/tkxmllint.html">tkxmllint</a> a GUI for 4670 xmllint and <a href="http://tclxml.sf.net/tkxsltproc.html">tkxsltproc</a> 4671 a GUI for xsltproc.</li> 4672</ul> 4673 4674<p></p> 4675</body> 4676</html> 4677
