xml.html revision 3cef119005159c12167770acb7ce4fbaaa6b3d89
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>xmlDocDump() generates output on one line.</em> 319 <p>Libxml2 will not <strong>invent</strong> spaces in the content of a 320 document since <strong>all spaces in the content of a document are 321 significant</strong>. If you build a tree from the API and want 322 indentation:</p> 323 <ol> 324 <li>the correct way is to generate those yourself too.</li> 325 <li>the dangerous way is to ask libxml2 to add those blanks to your 326 content <strong>modifying the content of your document in the 327 process</strong>. The result may not be what you expect. There is 328 <strong>NO</strong> way to guarantee that such a modification won't 329 affect other parts of the content of your document. See <a 330 href="http://xmlsoft.org/html/libxml-parser.html#xmlKeepBlanksDefault">xmlKeepBlanksDefault 331 ()</a> and <a 332 href="http://xmlsoft.org/html/libxml-tree.html#xmlSaveFormatFile">xmlSaveFormatFile 333 ()</a></li> 334 </ol> 335 </li> 336 <li>Extra nodes in the document: 337 <p><em>For a XML file as below:</em></p> 338 <pre><?xml version="1.0"?> 339<PLAN xmlns="http://www.argus.ca/autotest/1.0/"> 340<NODE CommFlag="0"/> 341<NODE CommFlag="1"/> 342</PLAN></pre> 343 <p><em>after parsing it with the function 344 pxmlDoc=xmlParseFile(...);</em></p> 345 <p><em>I want to the get the content of the first node (node with the 346 CommFlag="0")</em></p> 347 <p><em>so I did it as following;</em></p> 348 <pre>xmlNodePtr pnode; 349pnode=pxmlDoc->children->children;</pre> 350 <p><em>but it does not work. If I change it to</em></p> 351 <pre>pnode=pxmlDoc->children->children->next;</pre> 352 <p><em>then it works. Can someone explain it to me.</em></p> 353 <p></p> 354 <p>In XML all characters in the content of the document are significant 355 <strong>including blanks and formatting line breaks</strong>.</p> 356 <p>The extra nodes you are wondering about are just that, text nodes with 357 the formatting spaces which are part of the document but that people tend 358 to forget. There is a function <a 359 href="http://xmlsoft.org/html/libxml-parser.html">xmlKeepBlanksDefault 360 ()</a> to remove those at parse time, but that's an heuristic, and its 361 use should be limited to cases where you are certain there is no 362 mixed-content in the document.</p> 363 </li> 364 <li><em>I get compilation errors of existing code like when accessing 365 <strong>root</strong> or <strong>child fields</strong> of nodes.</em> 366 <p>You are compiling code developed for libxml version 1 and using a 367 libxml2 development environment. Either switch back to libxml v1 devel or 368 even better fix the code to compile with libxml2 (or both) by <a 369 href="upgrade.html">following the instructions</a>.</p> 370 </li> 371 <li><em>I get compilation errors about non existing 372 <strong>xmlRootNode</strong> or <strong>xmlChildrenNode</strong> 373 fields.</em> 374 <p>The source code you are using has been <a 375 href="upgrade.html">upgraded</a> to be able to compile with both libxml 376 and libxml2, but you need to install a more recent version: 377 libxml(-devel) >= 1.8.8 or libxml2(-devel) >= 2.1.0</p> 378 </li> 379 <li><em>XPath implementation looks seriously broken</em> 380 <p>XPath implementation prior to 2.3.0 was really incomplete. Upgrade to 381 a recent version, there are no known bugs in the current version.</p> 382 </li> 383 <li><em>The example provided in the web page does not compile.</em> 384 <p>It's hard to maintain the documentation in sync with the code 385 <grin/> ...</p> 386 <p>Check the previous points 1/ and 2/ raised before, and please send 387 patches.</p> 388 </li> 389 <li><em>Where can I get more examples and information than provided on the 390 web page?</em> 391 <p>Ideally a libxml2 book would be nice. I have no such plan ... But you 392 can:</p> 393 <ul> 394 <li>check more deeply the <a href="html/libxml-lib.html">existing 395 generated doc</a></li> 396 <li>have a look at <a href="examples/index.html">the set of 397 examples</a>.</li> 398 <li>look for examples of use for libxml2 function using the Gnome code. 399 For example the following will query the full Gnome CVS base for the 400 use of the <strong>xmlAddChild()</strong> function: 401 <p><a 402 href="http://cvs.gnome.org/lxr/search?string=xmlAddChild">http://cvs.gnome.org/lxr/search?string=xmlAddChild</a></p> 403 <p>This may be slow, a large hardware donation to the gnome project 404 could cure this :-)</p> 405 </li> 406 <li><a 407 href="http://cvs.gnome.org/bonsai/rview.cgi?cvsroot=/cvs/gnome&dir=gnome-xml">Browse 408 the libxml2 source</a> , I try to write code as clean and documented 409 as possible, so looking at it may be helpful. In particular the code 410 of xmllint.c and of the various testXXX.c test programs should 411 provide good examples of how to do things with the library.</li> 412 </ul> 413 </li> 414 <li>What about C++ ? 415 <p>libxml2 is written in pure C in order to allow easy reuse on a number 416 of platforms, including embedded systems. I don't intend to convert to 417 C++.</p> 418 <p>There is however a C++ wrapper which may fulfill your needs:</p> 419 <ul> 420 <li>by Ari Johnson <ari@btigate.com>: 421 <p>Website: <a 422 href="http://libxmlplusplus.sourceforge.net/">http://libxmlplusplus.sourceforge.net/</a></p> 423 <p>Download: <a 424 href="http://sourceforge.net/project/showfiles.php?group_id=12999">http://sourceforge.net/project/showfiles.php?group_id=12999</a></p> 425 </li> 426 <!-- Website is currently unavailable as of 2003-08-02 427 <li>by Peter Jones <pjones@pmade.org> 428 <p>Website: <a 429 href="http://pmade.org/pjones/software/xmlwrapp/">http://pmade.org/pjones/software/xmlwrapp/</a></p> 430 </li> 431 --> 432 </ul> 433 </li> 434 <li>How to validate a document a posteriori ? 435 <p>It is possible to validate documents which had not been validated at 436 initial parsing time or documents which have been built from scratch 437 using the API. Use the <a 438 href="http://xmlsoft.org/html/libxml-valid.html#xmlValidateDtd">xmlValidateDtd()</a> 439 function. It is also possible to simply add a DTD to an existing 440 document:</p> 441 <pre>xmlDocPtr doc; /* your existing document */ 442xmlDtdPtr dtd = xmlParseDTD(NULL, filename_of_dtd); /* parse the DTD */ 443 444 dtd->name = xmlStrDup((xmlChar*)"root_name"); /* use the given root */ 445 446 doc->intSubset = dtd; 447 if (doc->children == NULL) xmlAddChild((xmlNodePtr)doc, (xmlNodePtr)dtd); 448 else xmlAddPrevSibling(doc->children, (xmlNodePtr)dtd); 449 </pre> 450 </li> 451 <li>So what is this funky "xmlChar" used all the time? 452 <p>It is a null terminated sequence of utf-8 characters. And only utf-8! 453 You need to convert strings encoded in different ways to utf-8 before 454 passing them to the API. This can be accomplished with the iconv library 455 for instance.</p> 456 </li> 457 <li>etc ...</li> 458</ol> 459 460<p></p> 461 462<h2><a name="Documentat">Developer Menu</a></h2> 463 464<p>There are several on-line resources related to using libxml:</p> 465<ol> 466 <li>Use the <a href="search.php">search engine</a> to look up 467 information.</li> 468 <li>Check the <a href="FAQ.html">FAQ.</a></li> 469 <li>Check the <a href="http://xmlsoft.org/html/libxml-lib.html">extensive 470 documentation</a> automatically extracted from code comments.</li> 471 <li>Look at the documentation about <a href="encoding.html">libxml 472 internationalization support</a>.</li> 473 <li>This page provides a global overview and <a href="example.html">some 474 examples</a> on how to use libxml.</li> 475 <li><a href="examples/index.html">Code examples</a></li> 476 <li>John Fleck's libxml2 tutorial: <a href="tutorial/index.html">html</a> 477 or <a href="tutorial/xmltutorial.pdf">pdf</a>.</li> 478 <li>If you need to parse large files, check the <a 479 href="xmlreader.html">xmlReader</a> API tutorial</li> 480 <li><a href="mailto:james@daa.com.au">James Henstridge</a> wrote <a 481 href="http://www.daa.com.au/~james/gnome/xml-sax/xml-sax.html">some nice 482 documentation</a> explaining how to use the libxml SAX interface.</li> 483 <li>George Lebl wrote <a 484 href="http://www-106.ibm.com/developerworks/library/l-gnome3/">an article 485 for IBM developerWorks</a> about using libxml.</li> 486 <li>Check <a href="http://cvs.gnome.org/lxr/source/gnome-xml/TODO">the TODO 487 file</a>.</li> 488 <li>Read the <a href="upgrade.html">1.x to 2.x upgrade path</a> 489 description. If you are starting a new project using libxml you should 490 really use the 2.x version.</li> 491 <li>And don't forget to look at the <a 492 href="http://mail.gnome.org/archives/xml/">mailing-list archive</a>.</li> 493</ol> 494 495<h2><a name="Reporting">Reporting bugs and getting help</a></h2> 496 497<p>Well, bugs or missing features are always possible, and I will make a 498point of fixing them in a timely fashion. The best way to report a bug is to 499use the <a href="http://bugzilla.gnome.org/buglist.cgi?product=libxml2">Gnome 500bug tracking database</a> (make sure to use the "libxml2" module name). I 501look at reports there regularly and it's good to have a reminder when a bug 502is still open. Be sure to specify that the bug is for the package libxml2.</p> 503 504<p>For small problems you can try to get help on IRC, the #xml channel on 505irc.gnome.org (port 6667) usually have a few person subscribed which may help 506(but there is no garantee and if a real issue is raised it should go on the 507mailing-list for archival).</p> 508 509<p>There is also a mailing-list <a 510href="mailto:xml@gnome.org">xml@gnome.org</a> for libxml, with an <a 511href="http://mail.gnome.org/archives/xml/">on-line archive</a> (<a 512href="http://xmlsoft.org/messages">old</a>). To subscribe to this list, 513please visit the <a 514href="http://mail.gnome.org/mailman/listinfo/xml">associated Web</a> page and 515follow the instructions. <strong>Do not send code, I won't debug it</strong> 516(but patches are really appreciated!).</p> 517 518<p>Please note that with the current amount of virus and SPAM, sending mail 519to the list without being subscribed won't work. There is *far too many 520bounces* (in the order of a thousand a day !) I cannot approve them manually 521anymore. If your mail to the list bounced waiting for administrator approval, 522it is LOST ! Repost it and fix the problem triggering the error.</p> 523 524<p>Check the following <strong><span style="color: #FF0000">before 525posting</span></strong>:</p> 526<ul> 527 <li>Read the <a href="FAQ.html">FAQ</a> and <a href="search.php">use the 528 search engine</a> to get information related to your problem.</li> 529 <li>Make sure you are <a href="ftp://xmlsoft.org/">using a recent 530 version</a>, and that the problem still shows up in a recent version.</li> 531 <li>Check the <a href="http://mail.gnome.org/archives/xml/">list 532 archives</a> to see if the problem was reported already. In this case 533 there is probably a fix available, similarly check the <a 534 href="http://bugzilla.gnome.org/buglist.cgi?product=libxml2">registered 535 open bugs</a>.</li> 536 <li>Make sure you can reproduce the bug with xmllint or one of the test 537 programs found in source in the distribution.</li> 538 <li>Please send the command showing the error as well as the input (as an 539 attachment)</li> 540</ul> 541 542<p>Then send the bug with associated information to reproduce it to the <a 543href="mailto:xml@gnome.org">xml@gnome.org</a> list; if it's really libxml 544related I will approve it. Please do not send mail to me directly, it makes 545things really hard to track and in some cases I am not the best person to 546answer a given question, ask on the list.</p> 547 548<p>To <span style="color: #E50000">be really clear about support</span>:</p> 549<ul> 550 <li>Support or help <span style="color: #E50000">requests MUST be sent to 551 the list or on bugzilla</span> in case of problems, so that the Question 552 and Answers can be shared publicly. Failing to do so carries the implicit 553 message "I want free support but I don't want to share the benefits with 554 others" and is not welcome. I will automatically Carbon-Copy the 555 xml@gnome.org mailing list for any technical reply made about libxml2 or 556 libxslt.</li> 557 <li>There is <span style="color: #E50000">no garantee of support</span>, if 558 your question remains unanswered after a week, repost it, making sure you 559 gave all the detail needed and the information requested.</li> 560 <li>Failing to provide information as requested or double checking first 561 for prior feedback also carries the implicit message "the time of the 562 library maintainers is less valuable than my time" and might not be 563 welcome.</li> 564</ul> 565 566<p>Of course, bugs reported with a suggested patch for fixing them will 567probably be processed faster than those without.</p> 568 569<p>If you're looking for help, a quick look at <a 570href="http://mail.gnome.org/archives/xml/">the list archive</a> may actually 571provide the answer. I usually send source samples when answering libxml2 572usage questions. The <a 573href="http://xmlsoft.org/html/book1.html">auto-generated documentation</a> is 574not as polished as I would like (i need to learn more about DocBook), but 575it's a good starting point.</p> 576 577<h2><a name="help">How to help</a></h2> 578 579<p>You can help the project in various ways, the best thing to do first is to 580subscribe to the mailing-list as explained before, check the <a 581href="http://mail.gnome.org/archives/xml/">archives </a>and the <a 582href="http://bugzilla.gnome.org/buglist.cgi?product=libxml2">Gnome bug 583database</a>:</p> 584<ol> 585 <li>Provide patches when you find problems.</li> 586 <li>Provide the diffs when you port libxml2 to a new platform. They may not 587 be integrated in all cases but help pinpointing portability problems 588 and</li> 589 <li>Provide documentation fixes (either as patches to the code comments or 590 as HTML diffs).</li> 591 <li>Provide new documentations pieces (translations, examples, etc 592 ...).</li> 593 <li>Check the TODO file and try to close one of the items.</li> 594 <li>Take one of the points raised in the archive or the bug database and 595 provide a fix. <a href="mailto:daniel@veillard.com">Get in touch with me 596 </a>before to avoid synchronization problems and check that the suggested 597 fix will fit in nicely :-)</li> 598</ol> 599 600<h2><a name="Downloads">Downloads</a></h2> 601 602<p>The latest versions of libxml2 can be found on the <a 603href="ftp://xmlsoft.org/">xmlsoft.org</a> server ( <a 604href="http://xmlsoft.org/sources/">HTTP</a>, <a 605href="ftp://xmlsoft.org/">FTP</a> and rsync are available), there is also 606mirrors (<a href="ftp://speakeasy.rpmfind.net/pub/libxml/">Seattle</a>, <a 607href="ftp://fr.rpmfind.net/pub/libxml/">France</a>) or on the <a 608href="ftp://ftp.gnome.org/pub/GNOME/MIRRORS.html">Gnome FTP server</a> as <a 609href="ftp://ftp.gnome.org/pub/GNOME/sources/libxml2/2.6/">source archive</a> 610, Antonin Sprinzl also provide <a href="ftp://gd.tuwien.ac.at/pub/libxml/">a 611mirror in Austria</a>. (NOTE that you need both the <a 612href="http://rpmfind.net/linux/RPM/libxml2.html">libxml(2)</a> and <a 613href="http://rpmfind.net/linux/RPM/libxml2-devel.html">libxml(2)-devel</a> 614packages installed to compile applications using libxml.)</p> 615 616<p>You can find all the history of libxml(2) and libxslt releases in the <a 617href="http://xmlsoft.org/sources/old/">old</a> directory. The precompiled 618Windows binaries made by Igor Zlatovic are available in the <a 619href="http://xmlsoft.org/sources/win32/">win32</a> directory.</p> 620 621<p>Binary ports:</p> 622<ul> 623 <li>Red Hat RPMs for i386 are available directly on <a 624 href="ftp://xmlsoft.org/">xmlsoft.org</a>, the source RPM will compile on 625 any architecture supported by Red Hat.</li> 626 <li><a href="mailto:igor@zlatkovic.com">Igor Zlatkovic</a> 627 is now the maintainer of the Windows port, <a 628 href="http://www.zlatkovic.com/projects/libxml/index.html">he provides 629 binaries</a>.</li> 630 <li><a href="mailto:Gary.Pennington@sun.com">Gary Pennington</a> provides 631 <a href="http://garypennington.net/libxml2/">Solaris binaries</a>.</li> 632 <li><a href="mailto:Steve.Ball@zveno.com">Steve Ball</a> provides <a 633 href="http://www.zveno.com/open_source/libxml2xslt.html">Mac Os X 634 binaries</a>.</li> 635 <li>The HP-UX porting center provides <a 636 href="http://hpux.connect.org.uk/hppd/hpux/Gnome/">HP-UX binaries</a></li> 637</ul> 638 639<p>If you know other supported binary ports, please <a 640href="http://veillard.com/">contact me</a>.</p> 641 642<p><a name="Snapshot">Snapshot:</a></p> 643<ul> 644 <li>Code from the W3C cvs base libxml2 module, updated hourly <a 645 href="ftp://xmlsoft.org/cvs-snapshot.tar.gz">cvs-snapshot.tar.gz</a>.</li> 646 <li>Docs, content of the web site, the list archive included <a 647 href="ftp://xmlsoft.org/libxml-docs.tar.gz">libxml-docs.tar.gz</a>.</li> 648</ul> 649 650<p><a name="Contribs">Contributions:</a></p> 651 652<p>I do accept external contributions, especially if compiling on another 653platform, get in touch with the list to upload the package, wrappers for 654various languages have been provided, and can be found in the <a 655href="python.html">bindings section</a></p> 656 657<p>Libxml2 is also available from CVS:</p> 658<ul> 659 <li><p>The <a 660 href="http://cvs.gnome.org/viewcvs/libxml2/">Gnome 661 CVS base</a>. Check the <a 662 href="http://developer.gnome.org/tools/cvs.html">Gnome CVS Tools</a> 663 page; the CVS module is <b>libxml2</b>.</p> 664 </li> 665 <li>The <strong>libxslt</strong> module is also present there</li> 666</ul> 667 668<h2><a name="News">News</a></h2> 669 670<p>Items not finished and worked on, get in touch with the list if you want 671to help those</p> 672<ul> 673 <li>More testing on RelaxNG</li> 674 <li>Finishing up <a href="http://www.w3.org/TR/xmlschema-1/">XML 675 Schemas</a></li> 676</ul> 677 678<p>The <a href="ChangeLog.html">change log</a> describes the recents commits 679to the <a href="http://cvs.gnome.org/viewcvs/libxml2/">CVS</a> code base.</p> 680 681<p>There is the list of public releases:</p> 682 683<h3>2.6.11: July 5 2004</h3> 684<ul> 685 <li>Schemas: a lot of changes and improvements by Kasimier Buchcik for 686 attributes, namespaces and simple types.</li> 687 <li>build fixes: --with-minimum (William Brack), some gcc cleanup 688 (William), --with-thread-alloc (William)</li> 689 <li>portability: Windows binary package change (Igor Zlatkovic), Catalog 690 path on Windows</li> 691 <li>documentation: update to the tutorial (John Fleck), xmllint return code 692 (John Fleck), man pages (Ville Skytta), </li> 693 <li>bug fixes: C14N bug serializing namespaces (Aleksey Sanin), testSAX 694 properly initialize the library (William), empty node set in XPath 695 (William), xmlSchemas errors (William), invalid charref problem pointed 696 by Morus Walter, XInclude xml:base generation (William), Relax-NG bug 697 with div processing (William), XPointer and xml:base problem(William), 698 Reader and entities, xmllint return code for schemas (William), reader 699 streaming problem (Steve Ball), DTD serialization problem (William), 700 libxml.m4 fixes (Mike Hommey), do not provide destructors as methods on 701 Python classes, xmlReader buffer bug, Python bindings memory interfaces 702 improvement (with St�phane Bidoul), Fixed the push parser to be back to 703 synchronous behaviour.</li> 704 <li>improvement: custom per-thread I/O enhancement (Rob Richards), register 705 namespace in debug shell (Stefano Debenedetti), Python based regression 706 test for non-Unix users (William), dynamically increase the number of 707 XPath extension functions in Python and fix a memory leak (Marc-Antoine 708 Parent and William)</li> 709 <li>performance: hack done with Arjan van de Ven to reduce ELF footprint 710 and generated code on Linux, plus use gcc runtime profiling to optimize 711 the code generated in the RPM packages.</li> 712</ul> 713 714<h3>2.6.10: May 17 2004</h3> 715<ul> 716 <li>Web page generated for ChangeLog</li> 717 <li>build fixes: --without-html problems, make check without make all</li> 718 <li>portability: problem with xpath.c on Windows (MSC and Borland), memcmp 719 vs. strncmp on Solaris, XPath tests on Windows (Mark Vakoc), C++ do not 720 use "list" as parameter name, make tests work with Python 1.5 (Ed 721 Davis),</li> 722 <li>improvements: made xmlTextReaderMode public, small buffers resizing 723 (Morten Welinder), add --maxmem option to xmllint, add 724 xmlPopInputCallback() for Matt Sergeant, refactoring of serialization 725 escaping, added escaping customization</li> 726 <li>bugfixes: xsd:extension (Taihei Goi), assorted regexp bugs (William 727 Brack), xmlReader end of stream problem, node deregistration with reader, 728 URI escaping and filemanes, XHTML1 formatting (Nick Wellnhofer), regexp 729 transition reduction (William), various XSD Schemas fixes (Kasimier 730 Buchcik), XInclude fallback problem (William), weird problems with DTD 731 (William), structured error handler callback context (William), reverse 732 xmlEncodeSpecialChars() behaviour back to escaping '"'</li> 733</ul> 734 735<h3>2.6.9: Apr 18 2004</h3> 736<ul> 737 <li>implement xml:id Working Draft, relaxed XPath id() checking</li> 738 <li>bugfixes: xmlCtxtReset (Brent Hendricks), line number and CDATA (Dave 739 Beckett), Relax-NG compilation (William Brack), Regexp patches (with 740 William), xmlUriEscape (Mark Vakoc), a Relax-NG notAllowed problem (with 741 William), Relax-NG name classes compares (William), XInclude duplicate 742 fallback (William), external DTD encoding detection (William), a DTD 743 validation bug (William), xmlReader Close() fix, recusive extention 744 schemas</li> 745 <li>improvements: use xmlRead* APIs in test tools (Mark Vakoc), indenting 746 save optimization, better handle IIS broken HTTP redirect behaviour (Ian 747 Hummel), HTML parser frameset (James Bursa), libxml2-python RPM 748 dependancy, XML Schemas union support (Kasimier Buchcik), warning removal 749 clanup (William), keep ChangeLog compressed when installing from RPMs</li> 750 <li>documentation: examples and xmlDocDumpMemory docs (John Fleck), new 751 example (load, xpath, modify, save), xmlCatalogDump() comments,</li> 752 <li>Windows: Borland C++ builder (Eric Zurcher), work around Microsoft 753 compiler NaN handling bug (Mark Vakoc)</li> 754</ul> 755 756<h3>2.6.8: Mar 23 2004</h3> 757<ul> 758 <li>First step of the cleanup of the serialization code and APIs</li> 759 <li>XML Schemas: mixed content (Adam Dickmeiss), QName handling fixes (Adam 760 Dickmeiss), anyURI for "" (John Belmonte)</li> 761 <li>Python: Canonicalization C14N support added (Anthony Carrico)</li> 762 <li>xmlDocCopyNode() extension (William)</li> 763 <li>Relax-NG: fix when processing XInclude results (William), external 764 reference in interleave (William), missing error on <choice> 765 failure (William), memory leak in schemas datatype facets.</li> 766 <li>xmlWriter: patch for better DTD support (Alfred Mickautsch)</li> 767 <li>bug fixes: xmlXPathLangFunction memory leak (Mike Hommey and William 768 Brack), no ID errors if using HTML_PARSE_NOERROR, xmlcatalog fallbacks to 769 URI on SYSTEM lookup failure, XInclude parse flags inheritance (William), 770 XInclude and XPointer fixes for entities (William), XML parser bug 771 reported by Holger Rauch, nanohttp fd leak (William), regexps char 772 groups '-' handling (William), dictionnary reference counting problems, 773 do not close stderr.</li> 774 <li>performance patches from Petr Pajas</li> 775 <li>Documentation fixes: XML_CATALOG_FILES in man pages (Mike Hommey)</li> 776 <li>compilation and portability fixes: --without-valid, catalog cleanups 777 (Peter Breitenlohner), MingW patch (Roland Schwingel), cross-compilation 778 to Windows (Christophe de Vienne), --with-html-dir fixup (Julio Merino 779 Vidal), Windows build (Eric Zurcher)</li> 780</ul> 781 782<h3>2.6.7: Feb 23 2004</h3> 783<ul> 784 <li>documentation: tutorial updates (John Fleck), benchmark results</li> 785 <li>xmlWriter: updates and fixes (Alfred Mickautsch, Lucas Brasilino)</li> 786 <li>XPath optimization (Petr Pajas)</li> 787 <li>DTD ID handling optimization</li> 788 <li>bugfixes: xpath number with > 19 fractional (William Brack), push 789 mode with unescaped '>' characters, fix xmllint --stream --timing, fix 790 xmllint --memory --stream memory usage, xmlAttrSerializeTxtContent 791 handling NULL, trying to fix Relax-NG/Perl interface.</li> 792 <li>python: 2.3 compatibility, whitespace fixes (Malcolm Tredinnick)</li> 793 <li>Added relaxng option to xmllint --shell</li> 794</ul> 795 796<h3>2.6.6: Feb 12 2004</h3> 797<ul> 798 <li>nanohttp and nanoftp: buffer overflow error on URI parsing (Igor and 799 William) reported by Yuuichi Teranishi</li> 800 <li>bugfixes: make test and path issues, xmlWriter attribute serialization 801 (William Brack), xmlWriter indentation (William), schemas validation 802 (Eric Haszlakiewicz), XInclude dictionnaries issues (William and Oleg 803 Paraschenko), XInclude empty fallback (William), HTML warnings (William), 804 XPointer in XInclude (William), Python namespace serialization, 805 isolat1ToUTF8 bound error (Alfred Mickautsch), output of parameter 806 entities in internal subset (William), internal subset bug in push mode, 807 <xs:all> fix (Alexey Sarytchev)</li> 808 <li>Build: fix for automake-1.8 (Alexander Winston), warnings removal 809 (Philip Ludlam), SOCKLEN_T detection fixes (Daniel Richard), fix 810 --with-minimum configuration.</li> 811 <li>XInclude: allow the 2001 namespace without warning.</li> 812 <li>Documentation: missing example/index.html (John Fleck), version 813 dependancies (John Fleck)</li> 814 <li>reader API: structured error reporting (Steve Ball)</li> 815 <li>Windows compilation: mingw, msys (Mikhail Grushinskiy), function 816 prototype (Cameron Johnson), MSVC6 compiler warnings, _WINSOCKAPI_ 817 patch</li> 818 <li>Parsers: added xmlByteConsumed(ctxt) API to get the byte offest in 819 input.</li> 820</ul> 821 822<h3>2.6.5: Jan 25 2004</h3> 823<ul> 824 <li>Bugfixes: dictionnaries for schemas (William Brack), regexp segfault 825 (William), xs:all problem (William), a number of XPointer bugfixes 826 (William), xmllint error go to stderr, DTD validation problem with 827 namespace, memory leak (William), SAX1 cleanup and minimal options fixes 828 (Mark Vadoc), parser context reset on error (Shaun McCance), XPath union 829 evaluation problem (William) , xmlReallocLoc with NULL (Aleksey Sanin), 830 XML Schemas double free (Steve Ball), XInclude with no href, argument 831 callbacks order for XPath callbacks (Frederic Peters)</li> 832 <li>Documentation: python scripts (William Brack), xslt stylesheets (John 833 Fleck), doc (Sven Zimmerman), I/O example.</li> 834 <li>Python bindings: fixes (William), enum support (St�phane Bidoul), 835 structured error reporting (St�phane Bidoul)</li> 836 <li>XInclude: various fixes for conformance, problem related to dictionnary 837 references (William & me), recursion (William)</li> 838 <li>xmlWriter: indentation (Lucas Brasilino), memory leaks (Alfred 839 Mickautsch),</li> 840 <li>xmlSchemas: normalizedString datatype (John Belmonte)</li> 841 <li>code cleanup for strings functions (William)</li> 842 <li>Windows: compiler patches (Mark Vakoc)</li> 843 <li>Parser optimizations, a few new XPath and dictionnary APIs for future 844 XSLT optimizations.</li> 845</ul> 846 847<h3>2.6.4: Dec 24 2003</h3> 848<ul> 849 <li>Windows build fixes (Igor Zlatkovic)</li> 850 <li>Some serious XInclude problems reported by Oleg Paraschenko and</li> 851 <li>Unix and Makefile packaging fixes (me, William Brack,</li> 852 <li>Documentation improvements (John Fleck, William Brack), example fix 853 (Lucas Brasilino)</li> 854 <li>bugfixes: xmlTextReaderExpand() with xmlReaderWalker, XPath handling of 855 NULL strings (William Brack) , API building reader or parser from 856 filedescriptor should not close it, changed XPath sorting to be stable 857 again (William Brack), xmlGetNodePath() generating '(null)' (William 858 Brack), DTD validation and namespace bug (William Brack), XML Schemas 859 double inclusion behaviour</li> 860</ul> 861 862<h3>2.6.3: Dec 10 2003</h3> 863<ul> 864 <li>documentation updates and cleanup (DV, William Brack, John Fleck)</li> 865 <li>added a repository of examples, examples from Aleksey Sanin, Dodji 866 Seketeli, Alfred Mickautsch</li> 867 <li>Windows updates: Mark Vakoc, Igor Zlatkovic, Eric Zurcher, Mingw 868 (Kenneth Haley)</li> 869 <li>Unicode range checking (William Brack)</li> 870 <li>code cleanup (William Brack)</li> 871 <li>Python bindings: doc (John Fleck), bug fixes</li> 872 <li>UTF-16 cleanup and BOM issues (William Brack)</li> 873 <li>bug fixes: ID and xmlReader validation, XPath (William Brack), 874 xmlWriter (Alfred Mickautsch), hash.h inclusion problem, HTML parser 875 (James Bursa), attribute defaulting and validation, some serialization 876 cleanups, XML_GET_LINE macro, memory debug when using threads (William 877 Brack), serialization of attributes and entities content, xmlWriter 878 (Daniel Schulman)</li> 879 <li>XInclude bugfix, new APIs and update to the last version including the 880 namespace change.</li> 881 <li>XML Schemas improvements: include (Robert Stepanek), import and 882 namespace handling, fixed the regression tests troubles, added examples 883 based on Eric van der Vlist book, regexp fixes</li> 884 <li>preliminary pattern support for streaming (needed for schemas 885 constraints), added xmlTextReaderPreservePattern() to collect subdocument 886 when streaming.</li> 887 <li>various fixes in the structured error handling</li> 888</ul> 889 890<h3>2.6.2: Nov 4 2003</h3> 891<ul> 892 <li>XPath context unregistration fixes</li> 893 <li>text node coalescing fixes (Mark Lilback)</li> 894 <li>API to screate a W3C Schemas from an existing document (Steve Ball)</li> 895 <li>BeOS patches (Marcin 'Shard' Konicki)</li> 896 <li>xmlStrVPrintf function added (Aleksey Sanin)</li> 897 <li>compilation fixes (Mark Vakoc)</li> 898 <li>stdin parsing fix (William Brack)</li> 899 <li>a posteriori DTD validation fixes</li> 900 <li>xmlReader bug fixes: Walker fixes, python bindings</li> 901 <li>fixed xmlStopParser() to really stop the parser and errors</li> 902 <li>always generate line numbers when using the new xmlReadxxx 903 functions</li> 904 <li>added XInclude support to the xmlReader interface</li> 905 <li>implemented XML_PARSE_NONET parser option</li> 906 <li>DocBook XSLT processing bug fixed</li> 907 <li>HTML serialization for <p> elements (William Brack and me)</li> 908 <li>XPointer failure in XInclude are now handled as resource errors</li> 909 <li>fixed xmllint --html to use the HTML serializer on output (added 910 --xmlout to implement the previous behaviour of saving it using the XML 911 serializer)</li> 912</ul> 913 914<h3>2.6.1: Oct 28 2003</h3> 915<ul> 916 <li>Mostly bugfixes after the big 2.6.0 changes</li> 917 <li>Unix compilation patches: libxml.m4 (Patrick Welche), warnings cleanup 918 (William Brack)</li> 919 <li>Windows compilation patches (Joachim Bauch, Stephane Bidoul, Igor 920 Zlatkovic)</li> 921 <li>xmlWriter bugfix (Alfred Mickautsch)</li> 922 <li>chvalid.[ch]: couple of fixes from Stephane Bidoul</li> 923 <li>context reset: error state reset, push parser reset (Graham 924 Bennett)</li> 925 <li>context reuse: generate errors if file is not readable</li> 926 <li>defaulted attributes for element coming from internal entities 927 (Stephane Bidoul)</li> 928 <li>Python: tab and spaces mix (William Brack)</li> 929 <li>Error handler could crash in DTD validation in 2.6.0</li> 930 <li>xmlReader: do not use the document or element _private field</li> 931 <li>testSAX.c: avoid a problem with some PIs (Massimo Morara)</li> 932 <li>general bug fixes: mandatory encoding in text decl, serializing 933 Document Fragment nodes, xmlSearchNs 2.6.0 problem (Kasimier Buchcik), 934 XPath errors not reported, slow HTML parsing of large documents.</li> 935</ul> 936 937<h3>2.6.0: Oct 20 2003</h3> 938<ul> 939 <li>Major revision release: should be API and ABI compatible but got a lot 940 of change</li> 941 <li>Increased the library modularity, far more options can be stripped out, 942 a --with-minimum configuration will weight around 160KBytes</li> 943 <li>Use per parser and per document dictionnary, allocate names and small 944 text nodes from the dictionnary</li> 945 <li>Switch to a SAX2 like parser rewrote most of the XML parser core, 946 provides namespace resolution and defaulted attributes, minimize memory 947 allocations and copies, namespace checking and specific error handling, 948 immutable buffers, make predefined entities static structures, etc...</li> 949 <li>rewrote all the error handling in the library, all errors can be 950 intercepted at a structured level, with precise information 951 available.</li> 952 <li>New simpler and more generic XML and HTML parser APIs, allowing to 953 easilly modify the parsing options and reuse parser context for multiple 954 consecutive documents.</li> 955 <li>Similar new APIs for the xmlReader, for options and reuse, provided new 956 functions to access content as const strings, use them for Python 957 bindings</li> 958 <li>a lot of other smaller API improvements: xmlStrPrintf (Aleksey Sanin), 959 Walker i.e. reader on a document tree based on Alfred Mickautsch code, 960 make room in nodes for line numbers, reference counting and future PSVI 961 extensions, generation of character ranges to be checked with faster 962 algorithm (William), xmlParserMaxDepth (Crutcher Dunnavant), buffer 963 access</li> 964 <li>New xmlWriter API provided by Alfred Mickautsch</li> 965 <li>Schemas: base64 support by Anthony Carrico</li> 966 <li>Parser<->HTTP integration fix, proper processing of the Mime-Type 967 and charset informations if available.</li> 968 <li>Relax-NG: bug fixes including the one reported by Martijn Faassen and 969 zeroOrMore, better error reporting.</li> 970 <li>Python bindings (St�phane Bidoul), never use stdout for errors 971 output</li> 972 <li>Portability: all the headers have macros for export and calling 973 convention definitions (Igor Zlatkovic), VMS update (Craig A. Berry), 974 Windows: threads (Jesse Pelton), Borland compiler (Eric Zurcher, Igor), 975 Mingw (Igor), typos (Mark Vakoc), beta version (Stephane Bidoul), 976 warning cleanups on AIX and MIPS compilers (William Brack), BeOS (Marcin 977 'Shard' Konicki)</li> 978 <li>Documentation fixes and README (William Brack), search fix (William), 979 tutorial updates (John Fleck), namespace docs (Stefan Kost)</li> 980 <li>Bug fixes: xmlCleanupParser (Dave Beckett), threading uninitialized 981 mutexes, HTML doctype lowercase, SAX/IO (William), compression detection 982 and restore (William), attribute declaration in DTDs (William), namespace 983 on attribute in HTML output (William), input filename (Rob Richards), 984 namespace DTD validation, xmlReplaceNode (Chris Ryland), I/O callbacks 985 (Markus Keim), CDATA serialization (Shaun McCance), xmlReader (Peter 986 Derr), high codepoint charref like &#x10FFFF;, buffer access in push 987 mode (Justin Fletcher), TLS threads on Windows (Jesse Pelton), XPath bug 988 (William), xmlCleanupParser (Marc Liyanage), CDATA output (William), HTTP 989 error handling.</li> 990 <li>xmllint options: --dtdvalidfpi for Tobias Reif, --sax1 for compat 991 testing, --nodict for building without tree dictionnary, --nocdata to 992 replace CDATA by text, --nsclean to remove surperfluous namespace 993 declarations</li> 994 <li>added xml2-config --libtool-libs option from Kevin P. Fleming</li> 995 <li>a lot of profiling and tuning of the code, speedup patch for 996 xmlSearchNs() by Luca Padovani. The xmlReader should do far less 997 allocation and it speed should get closer to SAX. Chris Anderson worked 998 on speeding and cleaning up repetitive checking code.</li> 999 <li>cleanup of "make tests"</li> 1000 <li>libxml-2.0-uninstalled.pc from Malcolm Tredinnick</li> 1001 <li>deactivated the broken docBook SGML parser code and plugged the XML 1002 parser instead.</li> 1003</ul> 1004 1005<h3>2.5.11: Sep 9 2003</h3> 1006 1007<p>A bugfix only release:</p> 1008<ul> 1009 <li>risk of crash in Relax-NG</li> 1010 <li>risk of crash when using multithreaded programs</li> 1011</ul> 1012 1013<h3>2.5.10: Aug 15 2003</h3> 1014 1015<p>A bugfixes only release</p> 1016<ul> 1017 <li>Windows Makefiles (William Brack)</li> 1018 <li>UTF-16 support fixes (Mark Itzcovitz)</li> 1019 <li>Makefile and portability (William Brack) automake, Linux alpha, Mingw 1020 on Windows (Mikhail Grushinskiy)</li> 1021 <li>HTML parser (Oliver Stoeneberg)</li> 1022 <li>XInclude performance problem reported by Kevin Ruscoe</li> 1023 <li>XML parser performance problem reported by Grant Goodale</li> 1024 <li>xmlSAXParseDTD() bug fix from Malcolm Tredinnick</li> 1025 <li>and a couple other cleanup</li> 1026</ul> 1027 1028<h3>2.5.9: Aug 9 2003</h3> 1029<ul> 1030 <li>bugfixes: IPv6 portability, xmlHasNsProp (Markus Keim), Windows build 1031 (Wiliam Brake, Jesse Pelton, Igor), Schemas (Peter Sobisch), threading 1032 (Rob Richards), hexBinary type (), UTF-16 BOM (Dodji Seketeli), 1033 xmlReader, Relax-NG schemas compilation, namespace handling, EXSLT (Sean 1034 Griffin), HTML parsing problem (William Brack), DTD validation for mixed 1035 content + namespaces, HTML serialization, library initialization, 1036 progressive HTML parser</li> 1037 <li>better interfaces for Relax-NG error handling (Joachim Bauch, )</li> 1038 <li>adding xmlXIncludeProcessTree() for XInclud'ing in a subtree</li> 1039 <li>doc fixes and improvements (John Fleck)</li> 1040 <li>configure flag for -with-fexceptions when embedding in C++</li> 1041 <li>couple of new UTF-8 helper functions (William Brack)</li> 1042 <li>general encoding cleanup + ISO-8859-x without iconv (Peter Jacobi)</li> 1043 <li>xmlTextReader cleanup + enum for node types (Bjorn Reese)</li> 1044 <li>general compilation/warning cleanup Solaris/HP-UX/... (William 1045 Brack)</li> 1046</ul> 1047 1048<h3>2.5.8: Jul 6 2003</h3> 1049<ul> 1050 <li>bugfixes: XPath, XInclude, file/URI mapping, UTF-16 save (Mark 1051 Itzcovitz), UTF-8 checking, URI saving, error printing (William Brack), 1052 PI related memleak, compilation without schemas or without xpath (Joerg 1053 Schmitz-Linneweber/Garry Pennington), xmlUnlinkNode problem with DTDs, 1054 rpm problem on , i86_64, removed a few compilation problems from 2.5.7, 1055 xmlIOParseDTD, and xmlSAXParseDTD (Malcolm Tredinnick)</li> 1056 <li>portability: DJGPP (MsDos) , OpenVMS (Craig A. Berry)</li> 1057 <li>William Brack fixed multithreading lock problems</li> 1058 <li>IPv6 patch for FTP and HTTP accesses (Archana Shah/Wipro)</li> 1059 <li>Windows fixes (Igor Zlatkovic, Eric Zurcher), threading (St�phane 1060 Bidoul)</li> 1061 <li>A few W3C Schemas Structure improvements</li> 1062 <li>W3C Schemas Datatype improvements (Charlie Bozeman)</li> 1063 <li>Python bindings for thread globals (St�phane Bidoul), and method/class 1064 generator</li> 1065 <li>added --nonet option to xmllint</li> 1066 <li>documentation improvements (John Fleck)</li> 1067</ul> 1068 1069<h3>2.5.7: Apr 25 2003</h3> 1070<ul> 1071 <li>Relax-NG: Compiling to regexp and streaming validation on top of the 1072 xmlReader interface, added to xmllint --stream</li> 1073 <li>xmlReader: Expand(), Next() and DOM access glue, bug fixes</li> 1074 <li>Support for large files: RGN validated a 4.5GB instance</li> 1075 <li>Thread support is now configured in by default</li> 1076 <li>Fixes: update of the Trio code (Bjorn), WXS Date and Duration fixes 1077 (Charles Bozeman), DTD and namespaces (Brent Hendricks), HTML push parser 1078 and zero bytes handling, some missing Windows file path conversions, 1079 behaviour of the parser and validator in the presence of "out of memory" 1080 error conditions</li> 1081 <li>extended the API to be able to plug a garbage collecting memory 1082 allocator, added xmlMallocAtomic() and modified the allocations 1083 accordingly.</li> 1084 <li>Performances: removed excessive malloc() calls, speedup of the push and 1085 xmlReader interfaces, removed excessive thread locking</li> 1086 <li>Documentation: man page (John Fleck), xmlReader documentation</li> 1087 <li>Python: adding binding for xmlCatalogAddLocal (Brent M Hendricks)</li> 1088</ul> 1089 1090<h3>2.5.6: Apr 1 2003</h3> 1091<ul> 1092 <li>Fixed W3C XML Schemas datatype, should be compliant now except for 1093 binHex and base64 which are not supported yet.</li> 1094 <li>bug fixes: non-ASCII IDs, HTML output, XInclude on large docs and 1095 XInclude entities handling, encoding detection on external subsets, XML 1096 Schemas bugs and memory leaks, HTML parser (James Bursa)</li> 1097 <li>portability: python/trio (Albert Chin), Sun compiler warnings</li> 1098 <li>documentation: added --relaxng option to xmllint man page (John)</li> 1099 <li>improved error reporting: xml:space, start/end tag mismatches, Relax NG 1100 errors</li> 1101</ul> 1102 1103<h3>2.5.5: Mar 24 2003</h3> 1104<ul> 1105 <li>Lot of fixes on the Relax NG implementation. More testing including 1106 DocBook and TEI examples.</li> 1107 <li>Increased the support for W3C XML Schemas datatype</li> 1108 <li>Several bug fixes in the URI handling layer</li> 1109 <li>Bug fixes: HTML parser, xmlReader, DTD validation, XPath, encoding 1110 conversion, line counting in the parser.</li> 1111 <li>Added support for $XMLLINT_INDENT environment variable, FTP delete</li> 1112 <li>Fixed the RPM spec file name</li> 1113</ul> 1114 1115<h3>2.5.4: Feb 20 2003</h3> 1116<ul> 1117 <li>Conformance testing and lot of fixes on Relax NG and XInclude 1118 implementation</li> 1119 <li>Implementation of XPointer element() scheme</li> 1120 <li>Bug fixes: XML parser, XInclude entities merge, validity checking on 1121 namespaces, 1122 <p>2 serialization bugs, node info generation problems, a DTD regexp 1123 generation problem.</p> 1124 </li> 1125 <li>Portability: windows updates and path canonicalization (Igor)</li> 1126 <li>A few typo fixes (Kjartan Maraas)</li> 1127 <li>Python bindings generator fixes (Stephane Bidoul)</li> 1128</ul> 1129 1130<h3>2.5.3: Feb 10 2003</h3> 1131<ul> 1132 <li>RelaxNG and XML Schemas datatypes improvements, and added a first 1133 version of RelaxNG Python bindings</li> 1134 <li>Fixes: XLink (Sean Chittenden), XInclude (Sean Chittenden), API fix for 1135 serializing namespace nodes, encoding conversion bug, XHTML1 1136 serialization</li> 1137 <li>Portability fixes: Windows (Igor), AMD 64bits RPM spec file</li> 1138</ul> 1139 1140<h3>2.5.2: Feb 5 2003</h3> 1141<ul> 1142 <li>First implementation of RelaxNG, added --relaxng flag to xmllint</li> 1143 <li>Schemas support now compiled in by default.</li> 1144 <li>Bug fixes: DTD validation, namespace checking, XInclude and entities, 1145 delegateURI in XML Catalogs, HTML parser, XML reader (St�phane Bidoul), 1146 XPath parser and evaluation, UTF8ToUTF8 serialization, XML reader memory 1147 consumption, HTML parser, HTML serialization in the presence of 1148 namespaces</li> 1149 <li>added an HTML API to check elements and attributes.</li> 1150 <li>Documentation improvement, PDF for the tutorial (John Fleck), doc 1151 patches (Stefan Kost)</li> 1152 <li>Portability fixes: NetBSD (Julio Merino), Windows (Igor Zlatkovic)</li> 1153 <li>Added python bindings for XPointer, contextual error reporting 1154 (St�phane Bidoul)</li> 1155 <li>URI/file escaping problems (Stefano Zacchiroli)</li> 1156</ul> 1157 1158<h3>2.5.1: Jan 8 2003</h3> 1159<ul> 1160 <li>Fixes a memory leak and configuration/compilation problems in 2.5.0</li> 1161 <li>documentation updates (John)</li> 1162 <li>a couple of XmlTextReader fixes</li> 1163</ul> 1164 1165<h3>2.5.0: Jan 6 2003</h3> 1166<ul> 1167 <li>New <a href="xmlreader.html">XmltextReader interface</a> based on C# 1168 API (with help of St�phane Bidoul)</li> 1169 <li>Windows: more exports, including the new API (Igor)</li> 1170 <li>XInclude fallback fix</li> 1171 <li>Python: bindings for the new API, packaging (St�phane Bidoul), 1172 drv_libxml2.py Python xml.sax driver (St�phane Bidoul), fixes, speedup 1173 and iterators for Python-2.2 (Hannu Krosing)</li> 1174 <li>Tutorial fixes (john Fleck and Niraj Tolia) xmllint man update 1175 (John)</li> 1176 <li>Fix an XML parser bug raised by Vyacheslav Pindyura</li> 1177 <li>Fix for VMS serialization (Nigel Hall) and config (Craig A. Berry)</li> 1178 <li>Entities handling fixes</li> 1179 <li>new API to optionally track node creation and deletion (Lukas 1180 Schroeder)</li> 1181 <li>Added documentation for the XmltextReader interface and some <a 1182 href="guidelines.html">XML guidelines</a></li> 1183</ul> 1184 1185<h3>2.4.30: Dec 12 2002</h3> 1186<ul> 1187 <li>2.4.29 broke the python bindings, rereleasing</li> 1188 <li>Improvement/fixes of the XML API generator, and couple of minor code 1189 fixes.</li> 1190</ul> 1191 1192<h3>2.4.29: Dec 11 2002</h3> 1193<ul> 1194 <li>Windows fixes (Igor): Windows CE port, pthread linking, python bindings 1195 (St�phane Bidoul), Mingw (Magnus Henoch), and export list updates</li> 1196 <li>Fix for prev in python bindings (ERDI Gergo)</li> 1197 <li>Fix for entities handling (Marcus Clarke)</li> 1198 <li>Refactored the XML and HTML dumps to a single code path, fixed XHTML1 1199 dump</li> 1200 <li>Fix for URI parsing when handling URNs with fragment identifiers</li> 1201 <li>Fix for HTTP URL escaping problem</li> 1202 <li>added an TextXmlReader (C#) like API (work in progress)</li> 1203 <li>Rewrote the API in XML generation script, includes a C parser and saves 1204 more informations needed for C# bindings</li> 1205</ul> 1206 1207<h3>2.4.28: Nov 22 2002</h3> 1208<ul> 1209 <li>a couple of python binding fixes</li> 1210 <li>2 bug fixes in the XML push parser</li> 1211 <li>potential memory leak removed (Martin Stoilov)</li> 1212 <li>fix to the configure script for Unix (Dimitri Papadopoulos)</li> 1213 <li>added encoding support for XInclude parse="text"</li> 1214 <li>autodetection of XHTML1 and specific serialization rules added</li> 1215 <li>nasty threading bug fixed (William Brack)</li> 1216</ul> 1217 1218<h3>2.4.27: Nov 17 2002</h3> 1219<ul> 1220 <li>fixes for the Python bindings</li> 1221 <li>a number of bug fixes: SGML catalogs, xmlParseBalancedChunkMemory(), 1222 HTML parser, Schemas (Charles Bozeman), document fragment support 1223 (Christian Glahn), xmlReconciliateNs (Brian Stafford), XPointer, 1224 xmlFreeNode(), xmlSAXParseMemory (Peter Jones), xmlGetNodePath (Petr 1225 Pajas), entities processing</li> 1226 <li>added grep to xmllint --shell</li> 1227 <li>VMS update patch from Craig A. Berry</li> 1228 <li>cleanup of the Windows build with support for more compilers (Igor), 1229 better thread support on Windows</li> 1230 <li>cleanup of Unix Makefiles and spec file</li> 1231 <li>Improvements to the documentation (John Fleck)</li> 1232</ul> 1233 1234<h3>2.4.26: Oct 18 2002</h3> 1235<ul> 1236 <li>Patches for Windows CE port, improvements on Windows paths handling</li> 1237 <li>Fixes to the validation code (DTD and Schemas), xmlNodeGetPath() , 1238 HTML serialization, Namespace compliance, and a number of small 1239 problems</li> 1240</ul> 1241 1242<h3>2.4.25: Sep 26 2002</h3> 1243<ul> 1244 <li>A number of bug fixes: XPath, validation, Python bindings, DOM and 1245 tree, xmlI/O, Html</li> 1246 <li>Serious rewrite of XInclude</li> 1247 <li>Made XML Schemas regexp part of the default build and APIs, small fix 1248 and improvement of the regexp core</li> 1249 <li>Changed the validation code to reuse XML Schemas regexp APIs</li> 1250 <li>Better handling of Windows file paths, improvement of Makefiles (Igor, 1251 Daniel Gehriger, Mark Vakoc)</li> 1252 <li>Improved the python I/O bindings, the tests, added resolver and regexp 1253 APIs</li> 1254 <li>New logos from Marc Liyanage</li> 1255 <li>Tutorial improvements: John Fleck, Christopher Harris</li> 1256 <li>Makefile: Fixes for AMD x86_64 (Mandrake), DESTDIR (Christophe 1257 Merlet)</li> 1258 <li>removal of all stderr/perror use for error reporting</li> 1259 <li>Better error reporting: XPath and DTD validation</li> 1260 <li>update of the trio portability layer (Bjorn Reese)</li> 1261</ul> 1262 1263<p><strong>2.4.24: Aug 22 2002</strong></p> 1264<ul> 1265 <li>XPath fixes (William), xf:escape-uri() (Wesley Terpstra)</li> 1266 <li>Python binding fixes: makefiles (William), generator, rpm build, x86-64 1267 (fcrozat)</li> 1268 <li>HTML <style> and boolean attributes serializer fixes</li> 1269 <li>C14N improvements by Aleksey</li> 1270 <li>doc cleanups: Rick Jones</li> 1271 <li>Windows compiler makefile updates: Igor and Elizabeth Barham</li> 1272 <li>XInclude: implementation of fallback and xml:base fixup added</li> 1273</ul> 1274 1275<h3>2.4.23: July 6 2002</h3> 1276<ul> 1277 <li>performances patches: Peter Jacobi</li> 1278 <li>c14n fixes, testsuite and performances: Aleksey Sanin</li> 1279 <li>added xmlDocFormatDump: Chema Celorio</li> 1280 <li>new tutorial: John Fleck</li> 1281 <li>new hash functions and performances: Sander Vesik, portability fix from 1282 Peter Jacobi</li> 1283 <li>a number of bug fixes: XPath (William Brack, Richard Jinks), XML and 1284 HTML parsers, ID lookup function</li> 1285 <li>removal of all remaining sprintf: Aleksey Sanin</li> 1286</ul> 1287 1288<h3>2.4.22: May 27 2002</h3> 1289<ul> 1290 <li>a number of bug fixes: configure scripts, base handling, parser, memory 1291 usage, HTML parser, XPath, documentation (Christian Cornelssen), 1292 indentation, URI parsing</li> 1293 <li>Optimizations for XMLSec, fixing and making public some of the network 1294 protocol handlers (Aleksey)</li> 1295 <li>performance patch from Gary Pennington</li> 1296 <li>Charles Bozeman provided date and time support for XML Schemas 1297 datatypes</li> 1298</ul> 1299 1300<h3>2.4.21: Apr 29 2002</h3> 1301 1302<p>This release is both a bug fix release and also contains the early XML 1303Schemas <a href="http://www.w3.org/TR/xmlschema-1/">structures</a> and <a 1304href="http://www.w3.org/TR/xmlschema-2/">datatypes</a> code, beware, all 1305interfaces are likely to change, there is huge holes, it is clearly a work in 1306progress and don't even think of putting this code in a production system, 1307it's actually not compiled in by default. The real fixes are:</p> 1308<ul> 1309 <li>a couple of bugs or limitations introduced in 2.4.20</li> 1310 <li>patches for Borland C++ and MSC by Igor</li> 1311 <li>some fixes on XPath strings and conformance patches by Richard 1312 Jinks</li> 1313 <li>patch from Aleksey for the ExcC14N specification</li> 1314 <li>OSF/1 bug fix by Bjorn</li> 1315</ul> 1316 1317<h3>2.4.20: Apr 15 2002</h3> 1318<ul> 1319 <li>bug fixes: file descriptor leak, XPath, HTML output, DTD validation</li> 1320 <li>XPath conformance testing by Richard Jinks</li> 1321 <li>Portability fixes: Solaris, MPE/iX, Windows, OSF/1, python bindings, 1322 libxml.m4</li> 1323</ul> 1324 1325<h3>2.4.19: Mar 25 2002</h3> 1326<ul> 1327 <li>bug fixes: half a dozen XPath bugs, Validation, ISO-Latin to UTF8 1328 encoder</li> 1329 <li>portability fixes in the HTTP code</li> 1330 <li>memory allocation checks using valgrind, and profiling tests</li> 1331 <li>revamp of the Windows build and Makefiles</li> 1332</ul> 1333 1334<h3>2.4.18: Mar 18 2002</h3> 1335<ul> 1336 <li>bug fixes: tree, SAX, canonicalization, validation, portability, 1337 XPath</li> 1338 <li>removed the --with-buffer option it was becoming unmaintainable</li> 1339 <li>serious cleanup of the Python makefiles</li> 1340 <li>speedup patch to XPath very effective for DocBook stylesheets</li> 1341 <li>Fixes for Windows build, cleanup of the documentation</li> 1342</ul> 1343 1344<h3>2.4.17: Mar 8 2002</h3> 1345<ul> 1346 <li>a lot of bug fixes, including "namespace nodes have no parents in 1347 XPath"</li> 1348 <li>fixed/improved the Python wrappers, added more examples and more 1349 regression tests, XPath extension functions can now return node-sets</li> 1350 <li>added the XML Canonicalization support from Aleksey Sanin</li> 1351</ul> 1352 1353<h3>2.4.16: Feb 20 2002</h3> 1354<ul> 1355 <li>a lot of bug fixes, most of them were triggered by the XML Testsuite 1356 from OASIS and W3C. Compliance has been significantly improved.</li> 1357 <li>a couple of portability fixes too.</li> 1358</ul> 1359 1360<h3>2.4.15: Feb 11 2002</h3> 1361<ul> 1362 <li>Fixed the Makefiles, especially the python module ones</li> 1363 <li>A few bug fixes and cleanup</li> 1364 <li>Includes cleanup</li> 1365</ul> 1366 1367<h3>2.4.14: Feb 8 2002</h3> 1368<ul> 1369 <li>Change of License to the <a 1370 href="http://www.opensource.org/licenses/mit-license.html">MIT 1371 License</a> basically for integration in XFree86 codebase, and removing 1372 confusion around the previous dual-licensing</li> 1373 <li>added Python bindings, beta software but should already be quite 1374 complete</li> 1375 <li>a large number of fixes and cleanups, especially for all tree 1376 manipulations</li> 1377 <li>cleanup of the headers, generation of a reference API definition in 1378 XML</li> 1379</ul> 1380 1381<h3>2.4.13: Jan 14 2002</h3> 1382<ul> 1383 <li>update of the documentation: John Fleck and Charlie Bozeman</li> 1384 <li>cleanup of timing code from Justin Fletcher</li> 1385 <li>fixes for Windows and initial thread support on Win32: Igor and Serguei 1386 Narojnyi</li> 1387 <li>Cygwin patch from Robert Collins</li> 1388 <li>added xmlSetEntityReferenceFunc() for Keith Isdale work on xsldbg</li> 1389</ul> 1390 1391<h3>2.4.12: Dec 7 2001</h3> 1392<ul> 1393 <li>a few bug fixes: thread (Gary Pennington), xmllint (Geert Kloosterman), 1394 XML parser (Robin Berjon), XPointer (Danny Jamshy), I/O cleanups 1395 (robert)</li> 1396 <li>Eric Lavigne contributed project files for MacOS</li> 1397 <li>some makefiles cleanups</li> 1398</ul> 1399 1400<h3>2.4.11: Nov 26 2001</h3> 1401<ul> 1402 <li>fixed a couple of errors in the includes, fixed a few bugs, some code 1403 cleanups</li> 1404 <li>xmllint man pages improvement by Heiko Rupp</li> 1405 <li>updated VMS build instructions from John A Fotheringham</li> 1406 <li>Windows Makefiles updates from Igor</li> 1407</ul> 1408 1409<h3>2.4.10: Nov 10 2001</h3> 1410<ul> 1411 <li>URI escaping fix (Joel Young)</li> 1412 <li>added xmlGetNodePath() (for paths or XPointers generation)</li> 1413 <li>Fixes namespace handling problems when using DTD and validation</li> 1414 <li>improvements on xmllint: Morus Walter patches for --format and 1415 --encode, Stefan Kost and Heiko Rupp improvements on the --shell</li> 1416 <li>fixes for xmlcatalog linking pointed by Weiqi Gao</li> 1417 <li>fixes to the HTML parser</li> 1418</ul> 1419 1420<h3>2.4.9: Nov 6 2001</h3> 1421<ul> 1422 <li>fixes more catalog bugs</li> 1423 <li>avoid a compilation problem, improve xmlGetLineNo()</li> 1424</ul> 1425 1426<h3>2.4.8: Nov 4 2001</h3> 1427<ul> 1428 <li>fixed SGML catalogs broken in previous release, updated xmlcatalog 1429 tool</li> 1430 <li>fixed a compile errors and some includes troubles.</li> 1431</ul> 1432 1433<h3>2.4.7: Oct 30 2001</h3> 1434<ul> 1435 <li>exported some debugging interfaces</li> 1436 <li>serious rewrite of the catalog code</li> 1437 <li>integrated Gary Pennington thread safety patch, added configure option 1438 and regression tests</li> 1439 <li>removed an HTML parser bug</li> 1440 <li>fixed a couple of potentially serious validation bugs</li> 1441 <li>integrated the SGML DocBook support in xmllint</li> 1442 <li>changed the nanoftp anonymous login passwd</li> 1443 <li>some I/O cleanup and a couple of interfaces for Perl wrapper</li> 1444 <li>general bug fixes</li> 1445 <li>updated xmllint man page by John Fleck</li> 1446 <li>some VMS and Windows updates</li> 1447</ul> 1448 1449<h3>2.4.6: Oct 10 2001</h3> 1450<ul> 1451 <li>added an updated man pages by John Fleck</li> 1452 <li>portability and configure fixes</li> 1453 <li>an infinite loop on the HTML parser was removed (William)</li> 1454 <li>Windows makefile patches from Igor</li> 1455 <li>fixed half a dozen bugs reported for libxml or libxslt</li> 1456 <li>updated xmlcatalog to be able to modify SGML super catalogs</li> 1457</ul> 1458 1459<h3>2.4.5: Sep 14 2001</h3> 1460<ul> 1461 <li>Remove a few annoying bugs in 2.4.4</li> 1462 <li>forces the HTML serializer to output decimal charrefs since some 1463 version of Netscape can't handle hexadecimal ones</li> 1464</ul> 1465 1466<h3>1.8.16: Sep 14 2001</h3> 1467<ul> 1468 <li>maintenance release of the old libxml1 branch, couple of bug and 1469 portability fixes</li> 1470</ul> 1471 1472<h3>2.4.4: Sep 12 2001</h3> 1473<ul> 1474 <li>added --convert to xmlcatalog, bug fixes and cleanups of XML 1475 Catalog</li> 1476 <li>a few bug fixes and some portability changes</li> 1477 <li>some documentation cleanups</li> 1478</ul> 1479 1480<h3>2.4.3: Aug 23 2001</h3> 1481<ul> 1482 <li>XML Catalog support see the doc</li> 1483 <li>New NaN/Infinity floating point code</li> 1484 <li>A few bug fixes</li> 1485</ul> 1486 1487<h3>2.4.2: Aug 15 2001</h3> 1488<ul> 1489 <li>adds xmlLineNumbersDefault() to control line number generation</li> 1490 <li>lot of bug fixes</li> 1491 <li>the Microsoft MSC projects files should now be up to date</li> 1492 <li>inheritance of namespaces from DTD defaulted attributes</li> 1493 <li>fixes a serious potential security bug</li> 1494 <li>added a --format option to xmllint</li> 1495</ul> 1496 1497<h3>2.4.1: July 24 2001</h3> 1498<ul> 1499 <li>possibility to keep line numbers in the tree</li> 1500 <li>some computation NaN fixes</li> 1501 <li>extension of the XPath API</li> 1502 <li>cleanup for alpha and ia64 targets</li> 1503 <li>patch to allow saving through HTTP PUT or POST</li> 1504</ul> 1505 1506<h3>2.4.0: July 10 2001</h3> 1507<ul> 1508 <li>Fixed a few bugs in XPath, validation, and tree handling.</li> 1509 <li>Fixed XML Base implementation, added a couple of examples to the 1510 regression tests</li> 1511 <li>A bit of cleanup</li> 1512</ul> 1513 1514<h3>2.3.14: July 5 2001</h3> 1515<ul> 1516 <li>fixed some entities problems and reduce memory requirement when 1517 substituting them</li> 1518 <li>lots of improvements in the XPath queries interpreter can be 1519 substantially faster</li> 1520 <li>Makefiles and configure cleanups</li> 1521 <li>Fixes to XPath variable eval, and compare on empty node set</li> 1522 <li>HTML tag closing bug fixed</li> 1523 <li>Fixed an URI reference computation problem when validating</li> 1524</ul> 1525 1526<h3>2.3.13: June 28 2001</h3> 1527<ul> 1528 <li>2.3.12 configure.in was broken as well as the push mode XML parser</li> 1529 <li>a few more fixes for compilation on Windows MSC by Yon Derek</li> 1530</ul> 1531 1532<h3>1.8.14: June 28 2001</h3> 1533<ul> 1534 <li>Zbigniew Chyla gave a patch to use the old XML parser in push mode</li> 1535 <li>Small Makefile fix</li> 1536</ul> 1537 1538<h3>2.3.12: June 26 2001</h3> 1539<ul> 1540 <li>lots of cleanup</li> 1541 <li>a couple of validation fix</li> 1542 <li>fixed line number counting</li> 1543 <li>fixed serious problems in the XInclude processing</li> 1544 <li>added support for UTF8 BOM at beginning of entities</li> 1545 <li>fixed a strange gcc optimizer bugs in xpath handling of float, gcc-3.0 1546 miscompile uri.c (William), Thomas Leitner provided a fix for the 1547 optimizer on Tru64</li> 1548 <li>incorporated Yon Derek and Igor Zlatkovic fixes and improvements for 1549 compilation on Windows MSC</li> 1550 <li>update of libxml-doc.el (Felix Natter)</li> 1551 <li>fixed 2 bugs in URI normalization code</li> 1552</ul> 1553 1554<h3>2.3.11: June 17 2001</h3> 1555<ul> 1556 <li>updates to trio, Makefiles and configure should fix some portability 1557 problems (alpha)</li> 1558 <li>fixed some HTML serialization problems (pre, script, and block/inline 1559 handling), added encoding aware APIs, cleanup of this code</li> 1560 <li>added xmlHasNsProp()</li> 1561 <li>implemented a specific PI for encoding support in the DocBook SGML 1562 parser</li> 1563 <li>some XPath fixes (-Infinity, / as a function parameter and namespaces 1564 node selection)</li> 1565 <li>fixed a performance problem and an error in the validation code</li> 1566 <li>fixed XInclude routine to implement the recursive behaviour</li> 1567 <li>fixed xmlFreeNode problem when libxml is included statically twice</li> 1568 <li>added --version to xmllint for bug reports</li> 1569</ul> 1570 1571<h3>2.3.10: June 1 2001</h3> 1572<ul> 1573 <li>fixed the SGML catalog support</li> 1574 <li>a number of reported bugs got fixed, in XPath, iconv detection, 1575 XInclude processing</li> 1576 <li>XPath string function should now handle unicode correctly</li> 1577</ul> 1578 1579<h3>2.3.9: May 19 2001</h3> 1580 1581<p>Lots of bugfixes, and added a basic SGML catalog support:</p> 1582<ul> 1583 <li>HTML push bugfix #54891 and another patch from Jonas Borgstr�m</li> 1584 <li>some serious speed optimization again</li> 1585 <li>some documentation cleanups</li> 1586 <li>trying to get better linking on Solaris (-R)</li> 1587 <li>XPath API cleanup from Thomas Broyer</li> 1588 <li>Validation bug fixed #54631, added a patch from Gary Pennington, fixed 1589 xmlValidGetValidElements()</li> 1590 <li>Added an INSTALL file</li> 1591 <li>Attribute removal added to API: #54433</li> 1592 <li>added a basic support for SGML catalogs</li> 1593 <li>fixed xmlKeepBlanksDefault(0) API</li> 1594 <li>bugfix in xmlNodeGetLang()</li> 1595 <li>fixed a small configure portability problem</li> 1596 <li>fixed an inversion of SYSTEM and PUBLIC identifier in HTML document</li> 1597</ul> 1598 1599<h3>1.8.13: May 14 2001</h3> 1600<ul> 1601 <li>bugfixes release of the old libxml1 branch used by Gnome</li> 1602</ul> 1603 1604<h3>2.3.8: May 3 2001</h3> 1605<ul> 1606 <li>Integrated an SGML DocBook parser for the Gnome project</li> 1607 <li>Fixed a few things in the HTML parser</li> 1608 <li>Fixed some XPath bugs raised by XSLT use, tried to fix the floating 1609 point portability issue</li> 1610 <li>Speed improvement (8M/s for SAX, 3M/s for DOM, 1.5M/s for 1611 DOM+validation using the XML REC as input and a 700MHz celeron).</li> 1612 <li>incorporated more Windows cleanup</li> 1613 <li>added xmlSaveFormatFile()</li> 1614 <li>fixed problems in copying nodes with entities references (gdome)</li> 1615 <li>removed some troubles surrounding the new validation module</li> 1616</ul> 1617 1618<h3>2.3.7: April 22 2001</h3> 1619<ul> 1620 <li>lots of small bug fixes, corrected XPointer</li> 1621 <li>Non deterministic content model validation support</li> 1622 <li>added xmlDocCopyNode for gdome2</li> 1623 <li>revamped the way the HTML parser handles end of tags</li> 1624 <li>XPath: corrections of namespaces support and number formatting</li> 1625 <li>Windows: Igor Zlatkovic patches for MSC compilation</li> 1626 <li>HTML output fixes from P C Chow and William M. Brack</li> 1627 <li>Improved validation speed sensible for DocBook</li> 1628 <li>fixed a big bug with ID declared in external parsed entities</li> 1629 <li>portability fixes, update of Trio from Bjorn Reese</li> 1630</ul> 1631 1632<h3>2.3.6: April 8 2001</h3> 1633<ul> 1634 <li>Code cleanup using extreme gcc compiler warning options, found and 1635 cleared half a dozen potential problem</li> 1636 <li>the Eazel team found an XML parser bug</li> 1637 <li>cleaned up the user of some of the string formatting function. used the 1638 trio library code to provide the one needed when the platform is missing 1639 them</li> 1640 <li>xpath: removed a memory leak and fixed the predicate evaluation 1641 problem, extended the testsuite and cleaned up the result. XPointer seems 1642 broken ...</li> 1643</ul> 1644 1645<h3>2.3.5: Mar 23 2001</h3> 1646<ul> 1647 <li>Biggest change is separate parsing and evaluation of XPath expressions, 1648 there is some new APIs for this too</li> 1649 <li>included a number of bug fixes(XML push parser, 51876, notations, 1650 52299)</li> 1651 <li>Fixed some portability issues</li> 1652</ul> 1653 1654<h3>2.3.4: Mar 10 2001</h3> 1655<ul> 1656 <li>Fixed bugs #51860 and #51861</li> 1657 <li>Added a global variable xmlDefaultBufferSize to allow default buffer 1658 size to be application tunable.</li> 1659 <li>Some cleanup in the validation code, still a bug left and this part 1660 should probably be rewritten to support ambiguous content model :-\</li> 1661 <li>Fix a couple of serious bugs introduced or raised by changes in 2.3.3 1662 parser</li> 1663 <li>Fixed another bug in xmlNodeGetContent()</li> 1664 <li>Bjorn fixed XPath node collection and Number formatting</li> 1665 <li>Fixed a loop reported in the HTML parsing</li> 1666 <li>blank space are reported even if the Dtd content model proves that they 1667 are formatting spaces, this is for XML conformance</li> 1668</ul> 1669 1670<h3>2.3.3: Mar 1 2001</h3> 1671<ul> 1672 <li>small change in XPath for XSLT</li> 1673 <li>documentation cleanups</li> 1674 <li>fix in validation by Gary Pennington</li> 1675 <li>serious parsing performances improvements</li> 1676</ul> 1677 1678<h3>2.3.2: Feb 24 2001</h3> 1679<ul> 1680 <li>chasing XPath bugs, found a bunch, completed some TODO</li> 1681 <li>fixed a Dtd parsing bug</li> 1682 <li>fixed a bug in xmlNodeGetContent</li> 1683 <li>ID/IDREF support partly rewritten by Gary Pennington</li> 1684</ul> 1685 1686<h3>2.3.1: Feb 15 2001</h3> 1687<ul> 1688 <li>some XPath and HTML bug fixes for XSLT</li> 1689 <li>small extension of the hash table interfaces for DOM gdome2 1690 implementation</li> 1691 <li>A few bug fixes</li> 1692</ul> 1693 1694<h3>2.3.0: Feb 8 2001 (2.2.12 was on 25 Jan but I didn't kept track)</h3> 1695<ul> 1696 <li>Lots of XPath bug fixes</li> 1697 <li>Add a mode with Dtd lookup but without validation error reporting for 1698 XSLT</li> 1699 <li>Add support for text node without escaping (XSLT)</li> 1700 <li>bug fixes for xmlCheckFilename</li> 1701 <li>validation code bug fixes from Gary Pennington</li> 1702 <li>Patch from Paul D. Smith correcting URI path normalization</li> 1703 <li>Patch to allow simultaneous install of libxml-devel and 1704 libxml2-devel</li> 1705 <li>the example Makefile is now fixed</li> 1706 <li>added HTML to the RPM packages</li> 1707 <li>tree copying bugfixes</li> 1708 <li>updates to Windows makefiles</li> 1709 <li>optimization patch from Bjorn Reese</li> 1710</ul> 1711 1712<h3>2.2.11: Jan 4 2001</h3> 1713<ul> 1714 <li>bunch of bug fixes (memory I/O, xpath, ftp/http, ...)</li> 1715 <li>added htmlHandleOmittedElem()</li> 1716 <li>Applied Bjorn Reese's IPV6 first patch</li> 1717 <li>Applied Paul D. Smith patches for validation of XInclude results</li> 1718 <li>added XPointer xmlns() new scheme support</li> 1719</ul> 1720 1721<h3>2.2.10: Nov 25 2000</h3> 1722<ul> 1723 <li>Fix the Windows problems of 2.2.8</li> 1724 <li>integrate OpenVMS patches</li> 1725 <li>better handling of some nasty HTML input</li> 1726 <li>Improved the XPointer implementation</li> 1727 <li>integrate a number of provided patches</li> 1728</ul> 1729 1730<h3>2.2.9: Nov 25 2000</h3> 1731<ul> 1732 <li>erroneous release :-(</li> 1733</ul> 1734 1735<h3>2.2.8: Nov 13 2000</h3> 1736<ul> 1737 <li>First version of <a href="http://www.w3.org/TR/xinclude">XInclude</a> 1738 support</li> 1739 <li>Patch in conditional section handling</li> 1740 <li>updated MS compiler project</li> 1741 <li>fixed some XPath problems</li> 1742 <li>added an URI escaping function</li> 1743 <li>some other bug fixes</li> 1744</ul> 1745 1746<h3>2.2.7: Oct 31 2000</h3> 1747<ul> 1748 <li>added message redirection</li> 1749 <li>XPath improvements (thanks TOM !)</li> 1750 <li>xmlIOParseDTD() added</li> 1751 <li>various small fixes in the HTML, URI, HTTP and XPointer support</li> 1752 <li>some cleanup of the Makefile, autoconf and the distribution content</li> 1753</ul> 1754 1755<h3>2.2.6: Oct 25 2000:</h3> 1756<ul> 1757 <li>Added an hash table module, migrated a number of internal structure to 1758 those</li> 1759 <li>Fixed a posteriori validation problems</li> 1760 <li>HTTP module cleanups</li> 1761 <li>HTML parser improvements (tag errors, script/style handling, attribute 1762 normalization)</li> 1763 <li>coalescing of adjacent text nodes</li> 1764 <li>couple of XPath bug fixes, exported the internal API</li> 1765</ul> 1766 1767<h3>2.2.5: Oct 15 2000:</h3> 1768<ul> 1769 <li>XPointer implementation and testsuite</li> 1770 <li>Lot of XPath fixes, added variable and functions registration, more 1771 tests</li> 1772 <li>Portability fixes, lots of enhancements toward an easy Windows build 1773 and release</li> 1774 <li>Late validation fixes</li> 1775 <li>Integrated a lot of contributed patches</li> 1776 <li>added memory management docs</li> 1777 <li>a performance problem when using large buffer seems fixed</li> 1778</ul> 1779 1780<h3>2.2.4: Oct 1 2000:</h3> 1781<ul> 1782 <li>main XPath problem fixed</li> 1783 <li>Integrated portability patches for Windows</li> 1784 <li>Serious bug fixes on the URI and HTML code</li> 1785</ul> 1786 1787<h3>2.2.3: Sep 17 2000</h3> 1788<ul> 1789 <li>bug fixes</li> 1790 <li>cleanup of entity handling code</li> 1791 <li>overall review of all loops in the parsers, all sprintf usage has been 1792 checked too</li> 1793 <li>Far better handling of larges Dtd. Validating against DocBook XML Dtd 1794 works smoothly now.</li> 1795</ul> 1796 1797<h3>1.8.10: Sep 6 2000</h3> 1798<ul> 1799 <li>bug fix release for some Gnome projects</li> 1800</ul> 1801 1802<h3>2.2.2: August 12 2000</h3> 1803<ul> 1804 <li>mostly bug fixes</li> 1805 <li>started adding routines to access xml parser context options</li> 1806</ul> 1807 1808<h3>2.2.1: July 21 2000</h3> 1809<ul> 1810 <li>a purely bug fixes release</li> 1811 <li>fixed an encoding support problem when parsing from a memory block</li> 1812 <li>fixed a DOCTYPE parsing problem</li> 1813 <li>removed a bug in the function allowing to override the memory 1814 allocation routines</li> 1815</ul> 1816 1817<h3>2.2.0: July 14 2000</h3> 1818<ul> 1819 <li>applied a lot of portability fixes</li> 1820 <li>better encoding support/cleanup and saving (content is now always 1821 encoded in UTF-8)</li> 1822 <li>the HTML parser now correctly handles encodings</li> 1823 <li>added xmlHasProp()</li> 1824 <li>fixed a serious problem with &#38;</li> 1825 <li>propagated the fix to FTP client</li> 1826 <li>cleanup, bugfixes, etc ...</li> 1827 <li>Added a page about <a href="encoding.html">libxml Internationalization 1828 support</a></li> 1829</ul> 1830 1831<h3>1.8.9: July 9 2000</h3> 1832<ul> 1833 <li>fixed the spec the RPMs should be better</li> 1834 <li>fixed a serious bug in the FTP implementation, released 1.8.9 to solve 1835 rpmfind users problem</li> 1836</ul> 1837 1838<h3>2.1.1: July 1 2000</h3> 1839<ul> 1840 <li>fixes a couple of bugs in the 2.1.0 packaging</li> 1841 <li>improvements on the HTML parser</li> 1842</ul> 1843 1844<h3>2.1.0 and 1.8.8: June 29 2000</h3> 1845<ul> 1846 <li>1.8.8 is mostly a commodity package for upgrading to libxml2 according 1847 to <a href="upgrade.html">new instructions</a>. It fixes a nasty problem 1848 about &#38; charref parsing</li> 1849 <li>2.1.0 also ease the upgrade from libxml v1 to the recent version. it 1850 also contains numerous fixes and enhancements: 1851 <ul> 1852 <li>added xmlStopParser() to stop parsing</li> 1853 <li>improved a lot parsing speed when there is large CDATA blocs</li> 1854 <li>includes XPath patches provided by Picdar Technology</li> 1855 <li>tried to fix as much as possible DTD validation and namespace 1856 related problems</li> 1857 <li>output to a given encoding has been added/tested</li> 1858 <li>lot of various fixes</li> 1859 </ul> 1860 </li> 1861</ul> 1862 1863<h3>2.0.0: Apr 12 2000</h3> 1864<ul> 1865 <li>First public release of libxml2. If you are using libxml, it's a good 1866 idea to check the 1.x to 2.x upgrade instructions. NOTE: while initially 1867 scheduled for Apr 3 the release occurred only on Apr 12 due to massive 1868 workload.</li> 1869 <li>The include are now located under $prefix/include/libxml (instead of 1870 $prefix/include/gnome-xml), they also are referenced by 1871 <pre>#include <libxml/xxx.h></pre> 1872 <p>instead of</p> 1873 <pre>#include "xxx.h"</pre> 1874 </li> 1875 <li>a new URI module for parsing URIs and following strictly RFC 2396</li> 1876 <li>the memory allocation routines used by libxml can now be overloaded 1877 dynamically by using xmlMemSetup()</li> 1878 <li>The previously CVS only tool tester has been renamed 1879 <strong>xmllint</strong> and is now installed as part of the libxml2 1880 package</li> 1881 <li>The I/O interface has been revamped. There is now ways to plug in 1882 specific I/O modules, either at the URI scheme detection level using 1883 xmlRegisterInputCallbacks() or by passing I/O functions when creating a 1884 parser context using xmlCreateIOParserCtxt()</li> 1885 <li>there is a C preprocessor macro LIBXML_VERSION providing the version 1886 number of the libxml module in use</li> 1887 <li>a number of optional features of libxml can now be excluded at 1888 configure time (FTP/HTTP/HTML/XPath/Debug)</li> 1889</ul> 1890 1891<h3>2.0.0beta: Mar 14 2000</h3> 1892<ul> 1893 <li>This is a first Beta release of libxml version 2</li> 1894 <li>It's available only from<a href="ftp://xmlsoft.org/">xmlsoft.org 1895 FTP</a>, it's packaged as libxml2-2.0.0beta and available as tar and 1896 RPMs</li> 1897 <li>This version is now the head in the Gnome CVS base, the old one is 1898 available under the tag LIB_XML_1_X</li> 1899 <li>This includes a very large set of changes. From a programmatic point 1900 of view applications should not have to be modified too much, check the 1901 <a href="upgrade.html">upgrade page</a></li> 1902 <li>Some interfaces may changes (especially a bit about encoding).</li> 1903 <li>the updates includes: 1904 <ul> 1905 <li>fix I18N support. ISO-Latin-x/UTF-8/UTF-16 (nearly) seems correctly 1906 handled now</li> 1907 <li>Better handling of entities, especially well-formedness checking 1908 and proper PEref extensions in external subsets</li> 1909 <li>DTD conditional sections</li> 1910 <li>Validation now correctly handle entities content</li> 1911 <li><a href="http://rpmfind.net/tools/gdome/messages/0039.html">change 1912 structures to accommodate DOM</a></li> 1913 </ul> 1914 </li> 1915 <li>Serious progress were made toward compliance, <a 1916 href="conf/result.html">here are the result of the test</a> against the 1917 OASIS testsuite (except the Japanese tests since I don't support that 1918 encoding yet). This URL is rebuilt every couple of hours using the CVS 1919 head version.</li> 1920</ul> 1921 1922<h3>1.8.7: Mar 6 2000</h3> 1923<ul> 1924 <li>This is a bug fix release:</li> 1925 <li>It is possible to disable the ignorable blanks heuristic used by 1926 libxml-1.x, a new function xmlKeepBlanksDefault(0) will allow this. Note 1927 that for adherence to XML spec, this behaviour will be disabled by 1928 default in 2.x . The same function will allow to keep compatibility for 1929 old code.</li> 1930 <li>Blanks in <a> </a> constructs are not ignored anymore, 1931 avoiding heuristic is really the Right Way :-\</li> 1932 <li>The unchecked use of snprintf which was breaking libxml-1.8.6 1933 compilation on some platforms has been fixed</li> 1934 <li>nanoftp.c nanohttp.c: Fixed '#' and '?' stripping when processing 1935 URIs</li> 1936</ul> 1937 1938<h3>1.8.6: Jan 31 2000</h3> 1939<ul> 1940 <li>added a nanoFTP transport module, debugged until the new version of <a 1941 href="http://rpmfind.net/linux/rpm2html/rpmfind.html">rpmfind</a> can use 1942 it without troubles</li> 1943</ul> 1944 1945<h3>1.8.5: Jan 21 2000</h3> 1946<ul> 1947 <li>adding APIs to parse a well balanced chunk of XML (production <a 1948 href="http://www.w3.org/TR/REC-xml#NT-content">[43] content</a> of the 1949 XML spec)</li> 1950 <li>fixed a hideous bug in xmlGetProp pointed by Rune.Djurhuus@fast.no</li> 1951 <li>Jody Goldberg <jgoldberg@home.com> provided another patch trying 1952 to solve the zlib checks problems</li> 1953 <li>The current state in gnome CVS base is expected to ship as 1.8.5 with 1954 gnumeric soon</li> 1955</ul> 1956 1957<h3>1.8.4: Jan 13 2000</h3> 1958<ul> 1959 <li>bug fixes, reintroduced xmlNewGlobalNs(), fixed xmlNewNs()</li> 1960 <li>all exit() call should have been removed from libxml</li> 1961 <li>fixed a problem with INCLUDE_WINSOCK on WIN32 platform</li> 1962 <li>added newDocFragment()</li> 1963</ul> 1964 1965<h3>1.8.3: Jan 5 2000</h3> 1966<ul> 1967 <li>a Push interface for the XML and HTML parsers</li> 1968 <li>a shell-like interface to the document tree (try tester --shell :-)</li> 1969 <li>lots of bug fixes and improvement added over XMas holidays</li> 1970 <li>fixed the DTD parsing code to work with the xhtml DTD</li> 1971 <li>added xmlRemoveProp(), xmlRemoveID() and xmlRemoveRef()</li> 1972 <li>Fixed bugs in xmlNewNs()</li> 1973 <li>External entity loading code has been revamped, now it uses 1974 xmlLoadExternalEntity(), some fix on entities processing were added</li> 1975 <li>cleaned up WIN32 includes of socket stuff</li> 1976</ul> 1977 1978<h3>1.8.2: Dec 21 1999</h3> 1979<ul> 1980 <li>I got another problem with includes and C++, I hope this issue is fixed 1981 for good this time</li> 1982 <li>Added a few tree modification functions: xmlReplaceNode, 1983 xmlAddPrevSibling, xmlAddNextSibling, xmlNodeSetName and 1984 xmlDocSetRootElement</li> 1985 <li>Tried to improve the HTML output with help from <a 1986 href="mailto:clahey@umich.edu">Chris Lahey</a></li> 1987</ul> 1988 1989<h3>1.8.1: Dec 18 1999</h3> 1990<ul> 1991 <li>various patches to avoid troubles when using libxml with C++ compilers 1992 the "namespace" keyword and C escaping in include files</li> 1993 <li>a problem in one of the core macros IS_CHAR was corrected</li> 1994 <li>fixed a bug introduced in 1.8.0 breaking default namespace processing, 1995 and more specifically the Dia application</li> 1996 <li>fixed a posteriori validation (validation after parsing, or by using a 1997 Dtd not specified in the original document)</li> 1998 <li>fixed a bug in</li> 1999</ul> 2000 2001<h3>1.8.0: Dec 12 1999</h3> 2002<ul> 2003 <li>cleanup, especially memory wise</li> 2004 <li>the parser should be more reliable, especially the HTML one, it should 2005 not crash, whatever the input !</li> 2006 <li>Integrated various patches, especially a speedup improvement for large 2007 dataset from <a href="mailto:cnygard@bellatlantic.net">Carl Nygard</a>, 2008 configure with --with-buffers to enable them.</li> 2009 <li>attribute normalization, oops should have been added long ago !</li> 2010 <li>attributes defaulted from DTDs should be available, xmlSetProp() now 2011 does entities escaping by default.</li> 2012</ul> 2013 2014<h3>1.7.4: Oct 25 1999</h3> 2015<ul> 2016 <li>Lots of HTML improvement</li> 2017 <li>Fixed some errors when saving both XML and HTML</li> 2018 <li>More examples, the regression tests should now look clean</li> 2019 <li>Fixed a bug with contiguous charref</li> 2020</ul> 2021 2022<h3>1.7.3: Sep 29 1999</h3> 2023<ul> 2024 <li>portability problems fixed</li> 2025 <li>snprintf was used unconditionally, leading to link problems on system 2026 were it's not available, fixed</li> 2027</ul> 2028 2029<h3>1.7.1: Sep 24 1999</h3> 2030<ul> 2031 <li>The basic type for strings manipulated by libxml has been renamed in 2032 1.7.1 from <strong>CHAR</strong> to <strong>xmlChar</strong>. The reason 2033 is that CHAR was conflicting with a predefined type on Windows. However 2034 on non WIN32 environment, compatibility is provided by the way of a 2035 <strong>#define </strong>.</li> 2036 <li>Changed another error : the use of a structure field called errno, and 2037 leading to troubles on platforms where it's a macro</li> 2038</ul> 2039 2040<h3>1.7.0: Sep 23 1999</h3> 2041<ul> 2042 <li>Added the ability to fetch remote DTD or parsed entities, see the <a 2043 href="html/libxml-nanohttp.html">nanohttp</a> module.</li> 2044 <li>Added an errno to report errors by another mean than a simple printf 2045 like callback</li> 2046 <li>Finished ID/IDREF support and checking when validation</li> 2047 <li>Serious memory leaks fixed (there is now a <a 2048 href="html/libxml-xmlmemory.html">memory wrapper</a> module)</li> 2049 <li>Improvement of <a href="http://www.w3.org/TR/xpath">XPath</a> 2050 implementation</li> 2051 <li>Added an HTML parser front-end</li> 2052</ul> 2053 2054<h2><a name="XML">XML</a></h2> 2055 2056<p><a href="http://www.w3.org/TR/REC-xml">XML is a standard</a> for 2057markup-based structured documents. Here is <a name="example">an example XML 2058document</a>:</p> 2059<pre><?xml version="1.0"?> 2060<EXAMPLE prop1="gnome is great" prop2="&amp; linux too"> 2061 <head> 2062 <title>Welcome to Gnome</title> 2063 </head> 2064 <chapter> 2065 <title>The Linux adventure</title> 2066 <p>bla bla bla ...</p> 2067 <image href="linus.gif"/> 2068 <p>...</p> 2069 </chapter> 2070</EXAMPLE></pre> 2071 2072<p>The first line specifies that it is an XML document and gives useful 2073information about its encoding. Then the rest of the document is a text 2074format whose structure is specified by tags between brackets. <strong>Each 2075tag opened has to be closed</strong>. XML is pedantic about this. However, if 2076a tag is empty (no content), a single tag can serve as both the opening and 2077closing tag if it ends with <code>/></code> rather than with 2078<code>></code>. Note that, for example, the image tag has no content (just 2079an attribute) and is closed by ending the tag with <code>/></code>.</p> 2080 2081<p>XML can be applied successfully to a wide range of tasks, ranging from 2082long term structured document maintenance (where it follows the steps of 2083SGML) to simple data encoding mechanisms like configuration file formatting 2084(glade), spreadsheets (gnumeric), or even shorter lived documents such as 2085WebDAV where it is used to encode remote calls between a client and a 2086server.</p> 2087 2088<h2><a name="XSLT">XSLT</a></h2> 2089 2090<p>Check <a href="http://xmlsoft.org/XSLT">the separate libxslt page</a></p> 2091 2092<p><a href="http://www.w3.org/TR/xslt">XSL Transformations</a>, is a 2093language for transforming XML documents into other XML documents (or 2094HTML/textual output).</p> 2095 2096<p>A separate library called libxslt is available implementing XSLT-1.0 for 2097libxml2. This module "libxslt" too can be found in the Gnome CVS base.</p> 2098 2099<p>You can check the <a 2100href="http://cvs.gnome.org/lxr/source/libxslt/FEATURES">features</a> 2101supported and the progresses on the <a 2102href="http://cvs.gnome.org/lxr/source/libxslt/ChangeLog" 2103name="Changelog">Changelog</a>.</p> 2104 2105<h2><a name="Python">Python and bindings</a></h2> 2106 2107<p>There are a number of language bindings and wrappers available for 2108libxml2, the list below is not exhaustive. Please contact the <a 2109href="http://mail.gnome.org/mailman/listinfo/xml-bindings">xml-bindings@gnome.org</a> 2110(<a href="http://mail.gnome.org/archives/xml-bindings/">archives</a>) in 2111order to get updates to this list or to discuss the specific topic of libxml2 2112or libxslt wrappers or bindings:</p> 2113<ul> 2114 <li><a href="http://libxmlplusplus.sourceforge.net/">Libxml++</a> seems the 2115 most up-to-date C++ bindings for libxml2, check the <a 2116 href="http://libxmlplusplus.sourceforge.net/reference/html/hierarchy.html">documentation</a> 2117 and the <a 2118 href="http://cvs.sourceforge.net/cgi-bin/viewcvs.cgi/libxmlplusplus/libxml%2b%2b/examples/">examples</a>.</li> 2119 <li>There is another <a href="http://libgdome-cpp.berlios.de/">C++ wrapper 2120 based on the gdome2 bindings</a> maintained by Tobias Peters.</li> 2121 <li>and a third C++ wrapper by Peter Jones <pjones@pmade.org> 2122 <p>Website: <a 2123 href="http://pmade.org/pjones/software/xmlwrapp/">http://pmade.org/pjones/software/xmlwrapp/</a></p> 2124 </li> 2125 <li><a 2126 href="http://mail.gnome.org/archives/xml/2001-March/msg00014.html">Matt 2127 Sergeant</a> developed <a 2128 href="http://axkit.org/download/">XML::LibXSLT</a>, a Perl wrapper for 2129 libxml2/libxslt as part of the <a href="http://axkit.com/">AxKit XML 2130 application server</a>.</li> 2131 <li>If you're interested into scripting XML processing, have a look at <a 2132 href="http://xsh.sourceforge.net/">XSH</a> an XML editing shell based on 2133 Libxml2 Perl bindings.</li> 2134 <li><a href="mailto:dkuhlman@cutter.rexx.com">Dave Kuhlman</a> provides an 2135 earlier version of the libxml/libxslt <a 2136 href="http://www.rexx.com/~dkuhlman">wrappers for Python</a>.</li> 2137 <li>Gopal.V and Peter Minten develop <a 2138 href="http://savannah.gnu.org/projects/libxmlsharp">libxml#</a>, a set of 2139 C# libxml2 bindings.</li> 2140 <li>Petr Kozelka provides <a 2141 href="http://sourceforge.net/projects/libxml2-pas">Pascal units to glue 2142 libxml2</a> with Kylix, Delphi and other Pascal compilers.</li> 2143 <li>Uwe Fechner also provides <a 2144 href="http://sourceforge.net/projects/idom2-pas/">idom2</a>, a DOM2 2145 implementation for Kylix2/D5/D6 from Borland.</li> 2146 <li>Wai-Sun "Squidster" Chia provides <a 2147 href="http://www.rubycolor.org/arc/redist/">bindings for Ruby</a> and 2148 libxml2 bindings are also available in Ruby through the <a 2149 href="http://libgdome-ruby.berlios.de/">libgdome-ruby</a> module 2150 maintained by Tobias Peters.</li> 2151 <li>Steve Ball and contributors maintains <a 2152 href="http://tclxml.sourceforge.net/">libxml2 and libxslt bindings for 2153 Tcl</a>.</li> 2154 <li>There is support for libxml2 in the DOM module of PHP.</li> 2155 <li><a href="http://savannah.gnu.org/projects/classpathx/">LibxmlJ</a> is 2156 an effort to create a 100% JAXP-compatible Java wrapper for libxml2 and 2157 libxslt as part of GNU ClasspathX project.</li> 2158 <li>Patrick McPhee provides Rexx bindings fof libxml2 and libxslt, look for 2159 <a href="http://www.interlog.com/~ptjm/software.html">RexxXML</a>.</li> 2160</ul> 2161 2162<p>The distribution includes a set of Python bindings, which are guaranteed 2163to be maintained as part of the library in the future, though the Python 2164interface have not yet reached the completeness of the C API.</p> 2165 2166<p><a href="mailto:stephane.bidoul@softwareag.com">St�phane Bidoul</a> 2167maintains <a href="http://users.skynet.be/sbi/libxml-python/">a Windows port 2168of the Python bindings</a>.</p> 2169 2170<p>Note to people interested in building bindings, the API is formalized as 2171<a href="libxml2-api.xml">an XML API description file</a> which allows to 2172automate a large part of the Python bindings, this includes function 2173descriptions, enums, structures, typedefs, etc... The Python script used to 2174build the bindings is python/generator.py in the source distribution.</p> 2175 2176<p>To install the Python bindings there are 2 options:</p> 2177<ul> 2178 <li>If you use an RPM based distribution, simply install the <a 2179 href="http://rpmfind.net/linux/rpm2html/search.php?query=libxml2-python">libxml2-python 2180 RPM</a> (and if needed the <a 2181 href="http://rpmfind.net/linux/rpm2html/search.php?query=libxslt-python">libxslt-python 2182 RPM</a>).</li> 2183 <li>Otherwise use the <a href="ftp://xmlsoft.org/python/">libxml2-python 2184 module distribution</a> corresponding to your installed version of 2185 libxml2 and libxslt. Note that to install it you will need both libxml2 2186 and libxslt installed and run "python setup.py build install" in the 2187 module tree.</li> 2188</ul> 2189 2190<p>The distribution includes a set of examples and regression tests for the 2191python bindings in the <code>python/tests</code> directory. Here are some 2192excerpts from those tests:</p> 2193 2194<h3>tst.py:</h3> 2195 2196<p>This is a basic test of the file interface and DOM navigation:</p> 2197<pre>import libxml2, sys 2198 2199doc = libxml2.parseFile("tst.xml") 2200if doc.name != "tst.xml": 2201 print "doc.name failed" 2202 sys.exit(1) 2203root = doc.children 2204if root.name != "doc": 2205 print "root.name failed" 2206 sys.exit(1) 2207child = root.children 2208if child.name != "foo": 2209 print "child.name failed" 2210 sys.exit(1) 2211doc.freeDoc()</pre> 2212 2213<p>The Python module is called libxml2; parseFile is the equivalent of 2214xmlParseFile (most of the bindings are automatically generated, and the xml 2215prefix is removed and the casing convention are kept). All node seen at the 2216binding level share the same subset of accessors:</p> 2217<ul> 2218 <li><code>name</code> : returns the node name</li> 2219 <li><code>type</code> : returns a string indicating the node type</li> 2220 <li><code>content</code> : returns the content of the node, it is based on 2221 xmlNodeGetContent() and hence is recursive.</li> 2222 <li><code>parent</code> , <code>children</code>, <code>last</code>, 2223 <code>next</code>, <code>prev</code>, <code>doc</code>, 2224 <code>properties</code>: pointing to the associated element in the tree, 2225 those may return None in case no such link exists.</li> 2226</ul> 2227 2228<p>Also note the need to explicitly deallocate documents with freeDoc() . 2229Reference counting for libxml2 trees would need quite a lot of work to 2230function properly, and rather than risk memory leaks if not implemented 2231correctly it sounds safer to have an explicit function to free a tree. The 2232wrapper python objects like doc, root or child are them automatically garbage 2233collected.</p> 2234 2235<h3>validate.py:</h3> 2236 2237<p>This test check the validation interfaces and redirection of error 2238messages:</p> 2239<pre>import libxml2 2240 2241#deactivate error messages from the validation 2242def noerr(ctx, str): 2243 pass 2244 2245libxml2.registerErrorHandler(noerr, None) 2246 2247ctxt = libxml2.createFileParserCtxt("invalid.xml") 2248ctxt.validate(1) 2249ctxt.parseDocument() 2250doc = ctxt.doc() 2251valid = ctxt.isValid() 2252doc.freeDoc() 2253if valid != 0: 2254 print "validity check failed"</pre> 2255 2256<p>The first thing to notice is the call to registerErrorHandler(), it 2257defines a new error handler global to the library. It is used to avoid seeing 2258the error messages when trying to validate the invalid document.</p> 2259 2260<p>The main interest of that test is the creation of a parser context with 2261createFileParserCtxt() and how the behaviour can be changed before calling 2262parseDocument() . Similarly the informations resulting from the parsing phase 2263are also available using context methods.</p> 2264 2265<p>Contexts like nodes are defined as class and the libxml2 wrappers maps the 2266C function interfaces in terms of objects method as much as possible. The 2267best to get a complete view of what methods are supported is to look at the 2268libxml2.py module containing all the wrappers.</p> 2269 2270<h3>push.py:</h3> 2271 2272<p>This test show how to activate the push parser interface:</p> 2273<pre>import libxml2 2274 2275ctxt = libxml2.createPushParser(None, "<foo", 4, "test.xml") 2276ctxt.parseChunk("/>", 2, 1) 2277doc = ctxt.doc() 2278 2279doc.freeDoc()</pre> 2280 2281<p>The context is created with a special call based on the 2282xmlCreatePushParser() from the C library. The first argument is an optional 2283SAX callback object, then the initial set of data, the length and the name of 2284the resource in case URI-References need to be computed by the parser.</p> 2285 2286<p>Then the data are pushed using the parseChunk() method, the last call 2287setting the third argument terminate to 1.</p> 2288 2289<h3>pushSAX.py:</h3> 2290 2291<p>this test show the use of the event based parsing interfaces. In this case 2292the parser does not build a document, but provides callback information as 2293the parser makes progresses analyzing the data being provided:</p> 2294<pre>import libxml2 2295log = "" 2296 2297class callback: 2298 def startDocument(self): 2299 global log 2300 log = log + "startDocument:" 2301 2302 def endDocument(self): 2303 global log 2304 log = log + "endDocument:" 2305 2306 def startElement(self, tag, attrs): 2307 global log 2308 log = log + "startElement %s %s:" % (tag, attrs) 2309 2310 def endElement(self, tag): 2311 global log 2312 log = log + "endElement %s:" % (tag) 2313 2314 def characters(self, data): 2315 global log 2316 log = log + "characters: %s:" % (data) 2317 2318 def warning(self, msg): 2319 global log 2320 log = log + "warning: %s:" % (msg) 2321 2322 def error(self, msg): 2323 global log 2324 log = log + "error: %s:" % (msg) 2325 2326 def fatalError(self, msg): 2327 global log 2328 log = log + "fatalError: %s:" % (msg) 2329 2330handler = callback() 2331 2332ctxt = libxml2.createPushParser(handler, "<foo", 4, "test.xml") 2333chunk = " url='tst'>b" 2334ctxt.parseChunk(chunk, len(chunk), 0) 2335chunk = "ar</foo>" 2336ctxt.parseChunk(chunk, len(chunk), 1) 2337 2338reference = "startDocument:startElement foo {'url': 'tst'}:" + \ 2339 "characters: bar:endElement foo:endDocument:" 2340if log != reference: 2341 print "Error got: %s" % log 2342 print "Expected: %s" % reference</pre> 2343 2344<p>The key object in that test is the handler, it provides a number of entry 2345points which can be called by the parser as it makes progresses to indicate 2346the information set obtained. The full set of callback is larger than what 2347the callback class in that specific example implements (see the SAX 2348definition for a complete list). The wrapper will only call those supplied by 2349the object when activated. The startElement receives the names of the element 2350and a dictionary containing the attributes carried by this element.</p> 2351 2352<p>Also note that the reference string generated from the callback shows a 2353single character call even though the string "bar" is passed to the parser 2354from 2 different call to parseChunk()</p> 2355 2356<h3>xpath.py:</h3> 2357 2358<p>This is a basic test of XPath wrappers support</p> 2359<pre>import libxml2 2360 2361doc = libxml2.parseFile("tst.xml") 2362ctxt = doc.xpathNewContext() 2363res = ctxt.xpathEval("//*") 2364if len(res) != 2: 2365 print "xpath query: wrong node set size" 2366 sys.exit(1) 2367if res[0].name != "doc" or res[1].name != "foo": 2368 print "xpath query: wrong node set value" 2369 sys.exit(1) 2370doc.freeDoc() 2371ctxt.xpathFreeContext()</pre> 2372 2373<p>This test parses a file, then create an XPath context to evaluate XPath 2374expression on it. The xpathEval() method execute an XPath query and returns 2375the result mapped in a Python way. String and numbers are natively converted, 2376and node sets are returned as a tuple of libxml2 Python nodes wrappers. Like 2377the document, the XPath context need to be freed explicitly, also not that 2378the result of the XPath query may point back to the document tree and hence 2379the document must be freed after the result of the query is used.</p> 2380 2381<h3>xpathext.py:</h3> 2382 2383<p>This test shows how to extend the XPath engine with functions written in 2384python:</p> 2385<pre>import libxml2 2386 2387def foo(ctx, x): 2388 return x + 1 2389 2390doc = libxml2.parseFile("tst.xml") 2391ctxt = doc.xpathNewContext() 2392libxml2.registerXPathFunction(ctxt._o, "foo", None, foo) 2393res = ctxt.xpathEval("foo(1)") 2394if res != 2: 2395 print "xpath extension failure" 2396doc.freeDoc() 2397ctxt.xpathFreeContext()</pre> 2398 2399<p>Note how the extension function is registered with the context (but that 2400part is not yet finalized, this may change slightly in the future).</p> 2401 2402<h3>tstxpath.py:</h3> 2403 2404<p>This test is similar to the previous one but shows how the extension 2405function can access the XPath evaluation context:</p> 2406<pre>def foo(ctx, x): 2407 global called 2408 2409 # 2410 # test that access to the XPath evaluation contexts 2411 # 2412 pctxt = libxml2.xpathParserContext(_obj=ctx) 2413 ctxt = pctxt.context() 2414 called = ctxt.function() 2415 return x + 1</pre> 2416 2417<p>All the interfaces around the XPath parser(or rather evaluation) context 2418are not finalized, but it should be sufficient to do contextual work at the 2419evaluation point.</p> 2420 2421<h3>Memory debugging:</h3> 2422 2423<p>last but not least, all tests starts with the following prologue:</p> 2424<pre>#memory debug specific 2425libxml2.debugMemory(1)</pre> 2426 2427<p>and ends with the following epilogue:</p> 2428<pre>#memory debug specific 2429libxml2.cleanupParser() 2430if libxml2.debugMemory(1) == 0: 2431 print "OK" 2432else: 2433 print "Memory leak %d bytes" % (libxml2.debugMemory(1)) 2434 libxml2.dumpMemory()</pre> 2435 2436<p>Those activate the memory debugging interface of libxml2 where all 2437allocated block in the library are tracked. The prologue then cleans up the 2438library state and checks that all allocated memory has been freed. If not it 2439calls dumpMemory() which saves that list in a <code>.memdump</code> file.</p> 2440 2441<h2><a name="architecture">libxml2 architecture</a></h2> 2442 2443<p>Libxml2 is made of multiple components; some of them are optional, and 2444most of the block interfaces are public. The main components are:</p> 2445<ul> 2446 <li>an Input/Output layer</li> 2447 <li>FTP and HTTP client layers (optional)</li> 2448 <li>an Internationalization layer managing the encodings support</li> 2449 <li>a URI module</li> 2450 <li>the XML parser and its basic SAX interface</li> 2451 <li>an HTML parser using the same SAX interface (optional)</li> 2452 <li>a SAX tree module to build an in-memory DOM representation</li> 2453 <li>a tree module to manipulate the DOM representation</li> 2454 <li>a validation module using the DOM representation (optional)</li> 2455 <li>an XPath module for global lookup in a DOM representation 2456 (optional)</li> 2457 <li>a debug module (optional)</li> 2458</ul> 2459 2460<p>Graphically this gives the following:</p> 2461 2462<p><img src="libxml.gif" alt="a graphical view of the various"></p> 2463 2464<p></p> 2465 2466<h2><a name="tree">The tree output</a></h2> 2467 2468<p>The parser returns a tree built during the document analysis. The value 2469returned is an <strong>xmlDocPtr</strong> (i.e., a pointer to an 2470<strong>xmlDoc</strong> structure). This structure contains information such 2471as the file name, the document type, and a <strong>children</strong> pointer 2472which is the root of the document (or more exactly the first child under the 2473root which is the document). The tree is made of <strong>xmlNode</strong>s, 2474chained in double-linked lists of siblings and with a children<->parent 2475relationship. An xmlNode can also carry properties (a chain of xmlAttr 2476structures). An attribute may have a value which is a list of TEXT or 2477ENTITY_REF nodes.</p> 2478 2479<p>Here is an example (erroneous with respect to the XML spec since there 2480should be only one ELEMENT under the root):</p> 2481 2482<p><img src="structure.gif" alt=" structure.gif "></p> 2483 2484<p>In the source package there is a small program (not installed by default) 2485called <strong>xmllint</strong> which parses XML files given as argument and 2486prints them back as parsed. This is useful for detecting errors both in XML 2487code and in the XML parser itself. It has an option <strong>--debug</strong> 2488which prints the actual in-memory structure of the document; here is the 2489result with the <a href="#example">example</a> given before:</p> 2490<pre>DOCUMENT 2491version=1.0 2492standalone=true 2493 ELEMENT EXAMPLE 2494 ATTRIBUTE prop1 2495 TEXT 2496 content=gnome is great 2497 ATTRIBUTE prop2 2498 ENTITY_REF 2499 TEXT 2500 content= linux too 2501 ELEMENT head 2502 ELEMENT title 2503 TEXT 2504 content=Welcome to Gnome 2505 ELEMENT chapter 2506 ELEMENT title 2507 TEXT 2508 content=The Linux adventure 2509 ELEMENT p 2510 TEXT 2511 content=bla bla bla ... 2512 ELEMENT image 2513 ATTRIBUTE href 2514 TEXT 2515 content=linus.gif 2516 ELEMENT p 2517 TEXT 2518 content=...</pre> 2519 2520<p>This should be useful for learning the internal representation model.</p> 2521 2522<h2><a name="interface">The SAX interface</a></h2> 2523 2524<p>Sometimes the DOM tree output is just too large to fit reasonably into 2525memory. In that case (and if you don't expect to save back the XML document 2526loaded using libxml), it's better to use the SAX interface of libxml. SAX is 2527a <strong>callback-based interface</strong> to the parser. Before parsing, 2528the application layer registers a customized set of callbacks which are 2529called by the library as it progresses through the XML input.</p> 2530 2531<p>To get more detailed step-by-step guidance on using the SAX interface of 2532libxml, see the <a 2533href="http://www.daa.com.au/~james/gnome/xml-sax/xml-sax.html">nice 2534documentation</a>.written by <a href="mailto:james@daa.com.au">James 2535Henstridge</a>.</p> 2536 2537<p>You can debug the SAX behaviour by using the <strong>testSAX</strong> 2538program located in the gnome-xml module (it's usually not shipped in the 2539binary packages of libxml, but you can find it in the tar source 2540distribution). Here is the sequence of callbacks that would be reported by 2541testSAX when parsing the example XML document shown earlier:</p> 2542<pre>SAX.setDocumentLocator() 2543SAX.startDocument() 2544SAX.getEntity(amp) 2545SAX.startElement(EXAMPLE, prop1='gnome is great', prop2='&amp; linux too') 2546SAX.characters( , 3) 2547SAX.startElement(head) 2548SAX.characters( , 4) 2549SAX.startElement(title) 2550SAX.characters(Welcome to Gnome, 16) 2551SAX.endElement(title) 2552SAX.characters( , 3) 2553SAX.endElement(head) 2554SAX.characters( , 3) 2555SAX.startElement(chapter) 2556SAX.characters( , 4) 2557SAX.startElement(title) 2558SAX.characters(The Linux adventure, 19) 2559SAX.endElement(title) 2560SAX.characters( , 4) 2561SAX.startElement(p) 2562SAX.characters(bla bla bla ..., 15) 2563SAX.endElement(p) 2564SAX.characters( , 4) 2565SAX.startElement(image, href='linus.gif') 2566SAX.endElement(image) 2567SAX.characters( , 4) 2568SAX.startElement(p) 2569SAX.characters(..., 3) 2570SAX.endElement(p) 2571SAX.characters( , 3) 2572SAX.endElement(chapter) 2573SAX.characters( , 1) 2574SAX.endElement(EXAMPLE) 2575SAX.endDocument()</pre> 2576 2577<p>Most of the other interfaces of libxml2 are based on the DOM tree-building 2578facility, so nearly everything up to the end of this document presupposes the 2579use of the standard DOM tree build. Note that the DOM tree itself is built by 2580a set of registered default callbacks, without internal specific 2581interface.</p> 2582 2583<h2><a name="Validation">Validation & DTDs</a></h2> 2584 2585<p>Table of Content:</p> 2586<ol> 2587 <li><a href="#General5">General overview</a></li> 2588 <li><a href="#definition">The definition</a></li> 2589 <li><a href="#Simple">Simple rules</a> 2590 <ol> 2591 <li><a href="#reference">How to reference a DTD from a document</a></li> 2592 <li><a href="#Declaring">Declaring elements</a></li> 2593 <li><a href="#Declaring1">Declaring attributes</a></li> 2594 </ol> 2595 </li> 2596 <li><a href="#Some">Some examples</a></li> 2597 <li><a href="#validate">How to validate</a></li> 2598 <li><a href="#Other">Other resources</a></li> 2599</ol> 2600 2601<h3><a name="General5">General overview</a></h3> 2602 2603<p>Well what is validation and what is a DTD ?</p> 2604 2605<p>DTD is the acronym for Document Type Definition. This is a description of 2606the content for a family of XML files. This is part of the XML 1.0 2607specification, and allows one to describe and verify that a given document 2608instance conforms to the set of rules detailing its structure and content.</p> 2609 2610<p>Validation is the process of checking a document against a DTD (more 2611generally against a set of construction rules).</p> 2612 2613<p>The validation process and building DTDs are the two most difficult parts 2614of the XML life cycle. Briefly a DTD defines all the possible elements to be 2615found within your document, what is the formal shape of your document tree 2616(by defining the allowed content of an element; either text, a regular 2617expression for the allowed list of children, or mixed content i.e. both text 2618and children). The DTD also defines the valid attributes for all elements and 2619the types of those attributes.</p> 2620 2621<h3><a name="definition1">The definition</a></h3> 2622 2623<p>The <a href="http://www.w3.org/TR/REC-xml">W3C XML Recommendation</a> (<a 2624href="http://www.xml.com/axml/axml.html">Tim Bray's annotated version of 2625Rev1</a>):</p> 2626<ul> 2627 <li><a href="http://www.w3.org/TR/REC-xml#elemdecls">Declaring 2628 elements</a></li> 2629 <li><a href="http://www.w3.org/TR/REC-xml#attdecls">Declaring 2630 attributes</a></li> 2631</ul> 2632 2633<p>(unfortunately) all this is inherited from the SGML world, the syntax is 2634ancient...</p> 2635 2636<h3><a name="Simple1">Simple rules</a></h3> 2637 2638<p>Writing DTDs can be done in many ways. The rules to build them if you need 2639something permanent or something which can evolve over time can be radically 2640different. Really complex DTDs like DocBook ones are flexible but quite 2641harder to design. I will just focus on DTDs for a formats with a fixed simple 2642structure. It is just a set of basic rules, and definitely not exhaustive nor 2643usable for complex DTD design.</p> 2644 2645<h4><a name="reference1">How to reference a DTD from a document</a>:</h4> 2646 2647<p>Assuming the top element of the document is <code>spec</code> and the dtd 2648is placed in the file <code>mydtd</code> in the subdirectory 2649<code>dtds</code> of the directory from where the document were loaded:</p> 2650 2651<p><code><!DOCTYPE spec SYSTEM "dtds/mydtd"></code></p> 2652 2653<p>Notes:</p> 2654<ul> 2655 <li>The system string is actually an URI-Reference (as defined in <a 2656 href="http://www.ietf.org/rfc/rfc2396.txt">RFC 2396</a>) so you can use a 2657 full URL string indicating the location of your DTD on the Web. This is a 2658 really good thing to do if you want others to validate your document.</li> 2659 <li>It is also possible to associate a <code>PUBLIC</code> identifier (a 2660 magic string) so that the DTD is looked up in catalogs on the client side 2661 without having to locate it on the web.</li> 2662 <li>A DTD contains a set of element and attribute declarations, but they 2663 don't define what the root of the document should be. This is explicitly 2664 told to the parser/validator as the first element of the 2665 <code>DOCTYPE</code> declaration.</li> 2666</ul> 2667 2668<h4><a name="Declaring2">Declaring elements</a>:</h4> 2669 2670<p>The following declares an element <code>spec</code>:</p> 2671 2672<p><code><!ELEMENT spec (front, body, back?)></code></p> 2673 2674<p>It also expresses that the spec element contains one <code>front</code>, 2675one <code>body</code> and one optional <code>back</code> children elements in 2676this order. The declaration of one element of the structure and its content 2677are done in a single declaration. Similarly the following declares 2678<code>div1</code> elements:</p> 2679 2680<p><code><!ELEMENT div1 (head, (p | list | note)*, div2?)></code></p> 2681 2682<p>which means div1 contains one <code>head</code> then a series of optional 2683<code>p</code>, <code>list</code>s and <code>note</code>s and then an 2684optional <code>div2</code>. And last but not least an element can contain 2685text:</p> 2686 2687<p><code><!ELEMENT b (#PCDATA)></code></p> 2688 2689<p><code>b</code> contains text or being of mixed content (text and elements 2690in no particular order):</p> 2691 2692<p><code><!ELEMENT p (#PCDATA|a|ul|b|i|em)*></code></p> 2693 2694<p><code>p </code>can contain text or <code>a</code>, <code>ul</code>, 2695<code>b</code>, <code>i </code>or <code>em</code> elements in no particular 2696order.</p> 2697 2698<h4><a name="Declaring1">Declaring attributes</a>:</h4> 2699 2700<p>Again the attributes declaration includes their content definition:</p> 2701 2702<p><code><!ATTLIST termdef name CDATA #IMPLIED></code></p> 2703 2704<p>means that the element <code>termdef</code> can have a <code>name</code> 2705attribute containing text (<code>CDATA</code>) and which is optional 2706(<code>#IMPLIED</code>). The attribute value can also be defined within a 2707set:</p> 2708 2709<p><code><!ATTLIST list type (bullets|ordered|glossary) 2710"ordered"></code></p> 2711 2712<p>means <code>list</code> element have a <code>type</code> attribute with 3 2713allowed values "bullets", "ordered" or "glossary" and which default to 2714"ordered" if the attribute is not explicitly specified.</p> 2715 2716<p>The content type of an attribute can be text (<code>CDATA</code>), 2717anchor/reference/references 2718(<code>ID</code>/<code>IDREF</code>/<code>IDREFS</code>), entity(ies) 2719(<code>ENTITY</code>/<code>ENTITIES</code>) or name(s) 2720(<code>NMTOKEN</code>/<code>NMTOKENS</code>). The following defines that a 2721<code>chapter</code> element can have an optional <code>id</code> attribute 2722of type <code>ID</code>, usable for reference from attribute of type 2723IDREF:</p> 2724 2725<p><code><!ATTLIST chapter id ID #IMPLIED></code></p> 2726 2727<p>The last value of an attribute definition can be <code>#REQUIRED 2728</code>meaning that the attribute has to be given, <code>#IMPLIED</code> 2729meaning that it is optional, or the default value (possibly prefixed by 2730<code>#FIXED</code> if it is the only allowed).</p> 2731 2732<p>Notes:</p> 2733<ul> 2734 <li>Usually the attributes pertaining to a given element are declared in a 2735 single expression, but it is just a convention adopted by a lot of DTD 2736 writers: 2737 <pre><!ATTLIST termdef 2738 id ID #REQUIRED 2739 name CDATA #IMPLIED></pre> 2740 <p>The previous construct defines both <code>id</code> and 2741 <code>name</code> attributes for the element <code>termdef</code>.</p> 2742 </li> 2743</ul> 2744 2745<h3><a name="Some1">Some examples</a></h3> 2746 2747<p>The directory <code>test/valid/dtds/</code> in the libxml2 distribution 2748contains some complex DTD examples. The example in the file 2749<code>test/valid/dia.xml</code> shows an XML file where the simple DTD is 2750directly included within the document.</p> 2751 2752<h3><a name="validate1">How to validate</a></h3> 2753 2754<p>The simplest way is to use the xmllint program included with libxml. The 2755<code>--valid</code> option turns-on validation of the files given as input. 2756For example the following validates a copy of the first revision of the XML 27571.0 specification:</p> 2758 2759<p><code>xmllint --valid --noout test/valid/REC-xml-19980210.xml</code></p> 2760 2761<p>the -- noout is used to disable output of the resulting tree.</p> 2762 2763<p>The <code>--dtdvalid dtd</code> allows validation of the document(s) 2764against a given DTD.</p> 2765 2766<p>Libxml2 exports an API to handle DTDs and validation, check the <a 2767href="http://xmlsoft.org/html/libxml-valid.html">associated 2768description</a>.</p> 2769 2770<h3><a name="Other1">Other resources</a></h3> 2771 2772<p>DTDs are as old as SGML. So there may be a number of examples on-line, I 2773will just list one for now, others pointers welcome:</p> 2774<ul> 2775 <li><a href="http://www.xml101.com:8081/dtd/">XML-101 DTD</a></li> 2776</ul> 2777 2778<p>I suggest looking at the examples found under test/valid/dtd and any of 2779the large number of books available on XML. The dia example in test/valid 2780should be both simple and complete enough to allow you to build your own.</p> 2781 2782<p></p> 2783 2784<h2><a name="Memory">Memory Management</a></h2> 2785 2786<p>Table of Content:</p> 2787<ol> 2788 <li><a href="#General3">General overview</a></li> 2789 <li><a href="#setting">Setting libxml2 set of memory routines</a></li> 2790 <li><a href="#cleanup">Cleaning up after parsing</a></li> 2791 <li><a href="#Debugging">Debugging routines</a></li> 2792 <li><a href="#General4">General memory requirements</a></li> 2793</ol> 2794 2795<h3><a name="General3">General overview</a></h3> 2796 2797<p>The module <code><a 2798href="http://xmlsoft.org/html/libxml-xmlmemory.html">xmlmemory.h</a></code> 2799provides the interfaces to the libxml2 memory system:</p> 2800<ul> 2801 <li>libxml2 does not use the libc memory allocator directly but xmlFree(), 2802 xmlMalloc() and xmlRealloc()</li> 2803 <li>those routines can be reallocated to a specific set of routine, by 2804 default the libc ones i.e. free(), malloc() and realloc()</li> 2805 <li>the xmlmemory.c module includes a set of debugging routine</li> 2806</ul> 2807 2808<h3><a name="setting">Setting libxml2 set of memory routines</a></h3> 2809 2810<p>It is sometimes useful to not use the default memory allocator, either for 2811debugging, analysis or to implement a specific behaviour on memory management 2812(like on embedded systems). Two function calls are available to do so:</p> 2813<ul> 2814 <li><a href="http://xmlsoft.org/html/libxml-xmlmemory.html">xmlMemGet 2815 ()</a> which return the current set of functions in use by the parser</li> 2816 <li><a 2817 href="http://xmlsoft.org/html/libxml-xmlmemory.html">xmlMemSetup()</a> 2818 which allow to set up a new set of memory allocation functions</li> 2819</ul> 2820 2821<p>Of course a call to xmlMemSetup() should probably be done before calling 2822any other libxml2 routines (unless you are sure your allocations routines are 2823compatibles).</p> 2824 2825<h3><a name="cleanup">Cleaning up after parsing</a></h3> 2826 2827<p>Libxml2 is not stateless, there is a few set of memory structures needing 2828allocation before the parser is fully functional (some encoding structures 2829for example). This also mean that once parsing is finished there is a tiny 2830amount of memory (a few hundred bytes) which can be recollected if you don't 2831reuse the parser immediately:</p> 2832<ul> 2833 <li><a href="http://xmlsoft.org/html/libxml-parser.html">xmlCleanupParser 2834 ()</a> is a centralized routine to free the parsing states. Note that it 2835 won't deallocate any produced tree if any (use the xmlFreeDoc() and 2836 related routines for this).</li> 2837 <li><a href="http://xmlsoft.org/html/libxml-parser.html">xmlInitParser 2838 ()</a> is the dual routine allowing to preallocate the parsing state 2839 which can be useful for example to avoid initialization reentrancy 2840 problems when using libxml2 in multithreaded applications</li> 2841</ul> 2842 2843<p>Generally xmlCleanupParser() is safe, if needed the state will be rebuild 2844at the next invocation of parser routines, but be careful of the consequences 2845in multithreaded applications.</p> 2846 2847<h3><a name="Debugging">Debugging routines</a></h3> 2848 2849<p>When configured using --with-mem-debug flag (off by default), libxml2 uses 2850a set of memory allocation debugging routines keeping track of all allocated 2851blocks and the location in the code where the routine was called. A couple of 2852other debugging routines allow to dump the memory allocated infos to a file 2853or call a specific routine when a given block number is allocated:</p> 2854<ul> 2855 <li><a 2856 href="http://xmlsoft.org/html/libxml-xmlmemory.html">xmlMallocLoc()</a> 2857 <a 2858 href="http://xmlsoft.org/html/libxml-xmlmemory.html">xmlReallocLoc()</a> 2859 and <a 2860 href="http://xmlsoft.org/html/libxml-xmlmemory.html">xmlMemStrdupLoc()</a> 2861 are the memory debugging replacement allocation routines</li> 2862 <li><a href="http://xmlsoft.org/html/libxml-xmlmemory.html">xmlMemoryDump 2863 ()</a> dumps all the informations about the allocated memory block lefts 2864 in the <code>.memdump</code> file</li> 2865</ul> 2866 2867<p>When developing libxml2 memory debug is enabled, the tests programs call 2868xmlMemoryDump () and the "make test" regression tests will check for any 2869memory leak during the full regression test sequence, this helps a lot 2870ensuring that libxml2 does not leak memory and bullet proof memory 2871allocations use (some libc implementations are known to be far too permissive 2872resulting in major portability problems!).</p> 2873 2874<p>If the .memdump reports a leak, it displays the allocation function and 2875also tries to give some informations about the content and structure of the 2876allocated blocks left. This is sufficient in most cases to find the culprit, 2877but not always. Assuming the allocation problem is reproducible, it is 2878possible to find more easily:</p> 2879<ol> 2880 <li>write down the block number xxxx not allocated</li> 2881 <li>export the environment variable XML_MEM_BREAKPOINT=xxxx , the easiest 2882 when using GDB is to simply give the command 2883 <p><code>set environment XML_MEM_BREAKPOINT xxxx</code></p> 2884 <p>before running the program.</p> 2885 </li> 2886 <li>run the program under a debugger and set a breakpoint on 2887 xmlMallocBreakpoint() a specific function called when this precise block 2888 is allocated</li> 2889 <li>when the breakpoint is reached you can then do a fine analysis of the 2890 allocation an step to see the condition resulting in the missing 2891 deallocation.</li> 2892</ol> 2893 2894<p>I used to use a commercial tool to debug libxml2 memory problems but after 2895noticing that it was not detecting memory leaks that simple mechanism was 2896used and proved extremely efficient until now. Lately I have also used <a 2897href="http://developer.kde.org/~sewardj/">valgrind</a> with quite some 2898success, it is tied to the i386 architecture since it works by emulating the 2899processor and instruction set, it is slow but extremely efficient, i.e. it 2900spot memory usage errors in a very precise way.</p> 2901 2902<h3><a name="General4">General memory requirements</a></h3> 2903 2904<p>How much libxml2 memory require ? It's hard to tell in average it depends 2905of a number of things:</p> 2906<ul> 2907 <li>the parser itself should work in a fixed amount of memory, except for 2908 information maintained about the stacks of names and entities locations. 2909 The I/O and encoding handlers will probably account for a few KBytes. 2910 This is true for both the XML and HTML parser (though the HTML parser 2911 need more state).</li> 2912 <li>If you are generating the DOM tree then memory requirements will grow 2913 nearly linear with the size of the data. In general for a balanced 2914 textual document the internal memory requirement is about 4 times the 2915 size of the UTF8 serialization of this document (example the XML-1.0 2916 recommendation is a bit more of 150KBytes and takes 650KBytes of main 2917 memory when parsed). Validation will add a amount of memory required for 2918 maintaining the external Dtd state which should be linear with the 2919 complexity of the content model defined by the Dtd</li> 2920 <li>If you need to work with fixed memory requirements or don't need the 2921 full DOM tree then using the <a href="xmlreader.html">xmlReader 2922 interface</a> is probably the best way to proceed, it still allows to 2923 validate or operate on subset of the tree if needed.</li> 2924 <li>If you don't care about the advanced features of libxml2 like 2925 validation, DOM, XPath or XPointer, don't use entities, need to work with 2926 fixed memory requirements, and try to get the fastest parsing possible 2927 then the SAX interface should be used, but it has known restrictions.</li> 2928</ul> 2929 2930<p></p> 2931 2932<h2><a name="Encodings">Encodings support</a></h2> 2933 2934<p>Table of Content:</p> 2935<ol> 2936 <li><a href="encoding.html#What">What does internationalization support 2937 mean ?</a></li> 2938 <li><a href="encoding.html#internal">The internal encoding, how and 2939 why</a></li> 2940 <li><a href="encoding.html#implemente">How is it implemented ?</a></li> 2941 <li><a href="encoding.html#Default">Default supported encodings</a></li> 2942 <li><a href="encoding.html#extend">How to extend the existing 2943 support</a></li> 2944</ol> 2945 2946<h3><a name="What">What does internationalization support mean ?</a></h3> 2947 2948<p>If you are not really familiar with Internationalization (usual shortcut 2949is I18N) , Unicode, characters and glyphs, I suggest you read a <a 2950href="http://www.tbray.org/ongoing/When/200x/2003/04/06/Unicode">presentation</a> 2951by Tim Bray on Unicode and why you should care about it.</p> 2952 2953<p>XML was designed from the start to allow the support of any character set 2954by using Unicode. Any conformant XML parser has to support the UTF-8 and 2955UTF-16 default encodings which can both express the full unicode ranges. UTF8 2956is a variable length encoding whose greatest points are to reuse the same 2957encoding for ASCII and to save space for Western encodings, but it is a bit 2958more complex to handle in practice. UTF-16 use 2 bytes per character (and 2959sometimes combines two pairs), it makes implementation easier, but looks a 2960bit overkill for Western languages encoding. Moreover the XML specification 2961allows the document to be encoded in other encodings at the condition that 2962they are clearly labeled as such. For example the following is a wellformed 2963XML document encoded in ISO-8859-1 and using accentuated letters that we 2964French like for both markup and content:</p> 2965<pre><?xml version="1.0" encoding="ISO-8859-1"?> 2966<tr�s>l�</tr�s></pre> 2967 2968<p>Having internationalization support in libxml2 means the following:</p> 2969<ul> 2970 <li>the document is properly parsed</li> 2971 <li>informations about it's encoding are saved</li> 2972 <li>it can be modified</li> 2973 <li>it can be saved in its original encoding</li> 2974 <li>it can also be saved in another encoding supported by libxml2 (for 2975 example straight UTF8 or even an ASCII form)</li> 2976</ul> 2977 2978<p>Another very important point is that the whole libxml2 API, with the 2979exception of a few routines to read with a specific encoding or save to a 2980specific encoding, is completely agnostic about the original encoding of the 2981document.</p> 2982 2983<p>It should be noted too that the HTML parser embedded in libxml2 now obey 2984the same rules too, the following document will be (as of 2.2.2) handled in 2985an internationalized fashion by libxml2 too:</p> 2986<pre><!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN" 2987 "http://www.w3.org/TR/REC-html40/loose.dtd"> 2988<html lang="fr"> 2989<head> 2990 <META HTTP-EQUIV="Content-Type" CONTENT="text/html; charset=ISO-8859-1"> 2991</head> 2992<body> 2993<p>W3C cr�e des standards pour le Web.</body> 2994</html></pre> 2995 2996<h3><a name="internal">The internal encoding, how and why</a></h3> 2997 2998<p>One of the core decisions was to force all documents to be converted to a 2999default internal encoding, and that encoding to be UTF-8, here are the 3000rationales for those choices:</p> 3001<ul> 3002 <li>keeping the native encoding in the internal form would force the libxml 3003 users (or the code associated) to be fully aware of the encoding of the 3004 original document, for examples when adding a text node to a document, 3005 the content would have to be provided in the document encoding, i.e. the 3006 client code would have to check it before hand, make sure it's conformant 3007 to the encoding, etc ... Very hard in practice, though in some specific 3008 cases this may make sense.</li> 3009 <li>the second decision was which encoding. From the XML spec only UTF8 and 3010 UTF16 really makes sense as being the two only encodings for which there 3011 is mandatory support. UCS-4 (32 bits fixed size encoding) could be 3012 considered an intelligent choice too since it's a direct Unicode mapping 3013 support. I selected UTF-8 on the basis of efficiency and compatibility 3014 with surrounding software: 3015 <ul> 3016 <li>UTF-8 while a bit more complex to convert from/to (i.e. slightly 3017 more costly to import and export CPU wise) is also far more compact 3018 than UTF-16 (and UCS-4) for a majority of the documents I see it used 3019 for right now (RPM RDF catalogs, advogato data, various configuration 3020 file formats, etc.) and the key point for today's computer 3021 architecture is efficient uses of caches. If one nearly double the 3022 memory requirement to store the same amount of data, this will trash 3023 caches (main memory/external caches/internal caches) and my take is 3024 that this harms the system far more than the CPU requirements needed 3025 for the conversion to UTF-8</li> 3026 <li>Most of libxml2 version 1 users were using it with straight ASCII 3027 most of the time, doing the conversion with an internal encoding 3028 requiring all their code to be rewritten was a serious show-stopper 3029 for using UTF-16 or UCS-4.</li> 3030 <li>UTF-8 is being used as the de-facto internal encoding standard for 3031 related code like the <a href="http://www.pango.org/">pango</a> 3032 upcoming Gnome text widget, and a lot of Unix code (yet another place 3033 where Unix programmer base takes a different approach from Microsoft 3034 - they are using UTF-16)</li> 3035 </ul> 3036 </li> 3037</ul> 3038 3039<p>What does this mean in practice for the libxml2 user:</p> 3040<ul> 3041 <li>xmlChar, the libxml2 data type is a byte, those bytes must be assembled 3042 as UTF-8 valid strings. The proper way to terminate an xmlChar * string 3043 is simply to append 0 byte, as usual.</li> 3044 <li>One just need to make sure that when using chars outside the ASCII set, 3045 the values has been properly converted to UTF-8</li> 3046</ul> 3047 3048<h3><a name="implemente">How is it implemented ?</a></h3> 3049 3050<p>Let's describe how all this works within libxml, basically the I18N 3051(internationalization) support get triggered only during I/O operation, i.e. 3052when reading a document or saving one. Let's look first at the reading 3053sequence:</p> 3054<ol> 3055 <li>when a document is processed, we usually don't know the encoding, a 3056 simple heuristic allows to detect UTF-16 and UCS-4 from encodings where 3057 the ASCII range (0-0x7F) maps with ASCII</li> 3058 <li>the xml declaration if available is parsed, including the encoding 3059 declaration. At that point, if the autodetected encoding is different 3060 from the one declared a call to xmlSwitchEncoding() is issued.</li> 3061 <li>If there is no encoding declaration, then the input has to be in either 3062 UTF-8 or UTF-16, if it is not then at some point when processing the 3063 input, the converter/checker of UTF-8 form will raise an encoding error. 3064 You may end-up with a garbled document, or no document at all ! Example: 3065 <pre>~/XML -> /xmllint err.xml 3066err.xml:1: error: Input is not proper UTF-8, indicate encoding ! 3067<tr�s>l�</tr�s> 3068 ^ 3069err.xml:1: error: Bytes: 0xE8 0x73 0x3E 0x6C 3070<tr�s>l�</tr�s> 3071 ^</pre> 3072 </li> 3073 <li>xmlSwitchEncoding() does an encoding name lookup, canonicalize it, and 3074 then search the default registered encoding converters for that encoding. 3075 If it's not within the default set and iconv() support has been compiled 3076 it, it will ask iconv for such an encoder. If this fails then the parser 3077 will report an error and stops processing: 3078 <pre>~/XML -> /xmllint err2.xml 3079err2.xml:1: error: Unsupported encoding UnsupportedEnc 3080<?xml version="1.0" encoding="UnsupportedEnc"?> 3081 ^</pre> 3082 </li> 3083 <li>From that point the encoder processes progressively the input (it is 3084 plugged as a front-end to the I/O module) for that entity. It captures 3085 and converts on-the-fly the document to be parsed to UTF-8. The parser 3086 itself just does UTF-8 checking of this input and process it 3087 transparently. The only difference is that the encoding information has 3088 been added to the parsing context (more precisely to the input 3089 corresponding to this entity).</li> 3090 <li>The result (when using DOM) is an internal form completely in UTF-8 3091 with just an encoding information on the document node.</li> 3092</ol> 3093 3094<p>Ok then what happens when saving the document (assuming you 3095collected/built an xmlDoc DOM like structure) ? It depends on the function 3096called, xmlSaveFile() will just try to save in the original encoding, while 3097xmlSaveFileTo() and xmlSaveFileEnc() can optionally save to a given 3098encoding:</p> 3099<ol> 3100 <li>if no encoding is given, libxml2 will look for an encoding value 3101 associated to the document and if it exists will try to save to that 3102 encoding, 3103 <p>otherwise everything is written in the internal form, i.e. UTF-8</p> 3104 </li> 3105 <li>so if an encoding was specified, either at the API level or on the 3106 document, libxml2 will again canonicalize the encoding name, lookup for a 3107 converter in the registered set or through iconv. If not found the 3108 function will return an error code</li> 3109 <li>the converter is placed before the I/O buffer layer, as another kind of 3110 buffer, then libxml2 will simply push the UTF-8 serialization to through 3111 that buffer, which will then progressively be converted and pushed onto 3112 the I/O layer.</li> 3113 <li>It is possible that the converter code fails on some input, for example 3114 trying to push an UTF-8 encoded Chinese character through the UTF-8 to 3115 ISO-8859-1 converter won't work. Since the encoders are progressive they 3116 will just report the error and the number of bytes converted, at that 3117 point libxml2 will decode the offending character, remove it from the 3118 buffer and replace it with the associated charRef encoding &#123; and 3119 resume the conversion. This guarantees that any document will be saved 3120 without losses (except for markup names where this is not legal, this is 3121 a problem in the current version, in practice avoid using non-ascii 3122 characters for tag or attribute names). A special "ascii" encoding name 3123 is used to save documents to a pure ascii form can be used when 3124 portability is really crucial</li> 3125</ol> 3126 3127<p>Here are a few examples based on the same test document:</p> 3128<pre>~/XML -> /xmllint isolat1 3129<?xml version="1.0" encoding="ISO-8859-1"?> 3130<tr�s>l�</tr�s> 3131~/XML -> /xmllint --encode UTF-8 isolat1 3132<?xml version="1.0" encoding="UTF-8"?> 3133<très>l� �</très> 3134~/XML -> </pre> 3135 3136<p>The same processing is applied (and reuse most of the code) for HTML I18N 3137processing. Looking up and modifying the content encoding is a bit more 3138difficult since it is located in a <meta> tag under the <head>, 3139so a couple of functions htmlGetMetaEncoding() and htmlSetMetaEncoding() have 3140been provided. The parser also attempts to switch encoding on the fly when 3141detecting such a tag on input. Except for that the processing is the same 3142(and again reuses the same code).</p> 3143 3144<h3><a name="Default">Default supported encodings</a></h3> 3145 3146<p>libxml2 has a set of default converters for the following encodings 3147(located in encoding.c):</p> 3148<ol> 3149 <li>UTF-8 is supported by default (null handlers)</li> 3150 <li>UTF-16, both little and big endian</li> 3151 <li>ISO-Latin-1 (ISO-8859-1) covering most western languages</li> 3152 <li>ASCII, useful mostly for saving</li> 3153 <li>HTML, a specific handler for the conversion of UTF-8 to ASCII with HTML 3154 predefined entities like &copy; for the Copyright sign.</li> 3155</ol> 3156 3157<p>More over when compiled on an Unix platform with iconv support the full 3158set of encodings supported by iconv can be instantly be used by libxml. On a 3159linux machine with glibc-2.1 the list of supported encodings and aliases fill 31603 full pages, and include UCS-4, the full set of ISO-Latin encodings, and the 3161various Japanese ones.</p> 3162 3163<h4>Encoding aliases</h4> 3164 3165<p>From 2.2.3, libxml2 has support to register encoding names aliases. The 3166goal is to be able to parse document whose encoding is supported but where 3167the name differs (for example from the default set of names accepted by 3168iconv). The following functions allow to register and handle new aliases for 3169existing encodings. Once registered libxml2 will automatically lookup the 3170aliases when handling a document:</p> 3171<ul> 3172 <li>int xmlAddEncodingAlias(const char *name, const char *alias);</li> 3173 <li>int xmlDelEncodingAlias(const char *alias);</li> 3174 <li>const char * xmlGetEncodingAlias(const char *alias);</li> 3175 <li>void xmlCleanupEncodingAliases(void);</li> 3176</ul> 3177 3178<h3><a name="extend">How to extend the existing support</a></h3> 3179 3180<p>Well adding support for new encoding, or overriding one of the encoders 3181(assuming it is buggy) should not be hard, just write input and output 3182conversion routines to/from UTF-8, and register them using 3183xmlNewCharEncodingHandler(name, xxxToUTF8, UTF8Toxxx), and they will be 3184called automatically if the parser(s) encounter such an encoding name 3185(register it uppercase, this will help). The description of the encoders, 3186their arguments and expected return values are described in the encoding.h 3187header.</p> 3188 3189<p>A quick note on the topic of subverting the parser to use a different 3190internal encoding than UTF-8, in some case people will absolutely want to 3191keep the internal encoding different, I think it's still possible (but the 3192encoding must be compliant with ASCII on the same subrange) though I didn't 3193tried it. The key is to override the default conversion routines (by 3194registering null encoders/decoders for your charsets), and bypass the UTF-8 3195checking of the parser by setting the parser context charset 3196(ctxt->charset) to something different than XML_CHAR_ENCODING_UTF8, but 3197there is no guarantee that this will work. You may also have some troubles 3198saving back.</p> 3199 3200<p>Basically proper I18N support is important, this requires at least 3201libxml-2.0.0, but a lot of features and corrections are really available only 3202starting 2.2.</p> 3203 3204<h2><a name="IO">I/O Interfaces</a></h2> 3205 3206<p>Table of Content:</p> 3207<ol> 3208 <li><a href="#General1">General overview</a></li> 3209 <li><a href="#basic">The basic buffer type</a></li> 3210 <li><a href="#Input">Input I/O handlers</a></li> 3211 <li><a href="#Output">Output I/O handlers</a></li> 3212 <li><a href="#entities">The entities loader</a></li> 3213 <li><a href="#Example2">Example of customized I/O</a></li> 3214</ol> 3215 3216<h3><a name="General1">General overview</a></h3> 3217 3218<p>The module <code><a 3219href="http://xmlsoft.org/html/libxml-xmlio.html">xmlIO.h</a></code> provides 3220the interfaces to the libxml2 I/O system. This consists of 4 main parts:</p> 3221<ul> 3222 <li>Entities loader, this is a routine which tries to fetch the entities 3223 (files) based on their PUBLIC and SYSTEM identifiers. The default loader 3224 don't look at the public identifier since libxml2 do not maintain a 3225 catalog. You can redefine you own entity loader by using 3226 <code>xmlGetExternalEntityLoader()</code> and 3227 <code>xmlSetExternalEntityLoader()</code>. <a href="#entities">Check the 3228 example</a>.</li> 3229 <li>Input I/O buffers which are a commodity structure used by the parser(s) 3230 input layer to handle fetching the informations to feed the parser. This 3231 provides buffering and is also a placeholder where the encoding 3232 converters to UTF8 are piggy-backed.</li> 3233 <li>Output I/O buffers are similar to the Input ones and fulfill similar 3234 task but when generating a serialization from a tree.</li> 3235 <li>A mechanism to register sets of I/O callbacks and associate them with 3236 specific naming schemes like the protocol part of the URIs. 3237 <p>This affect the default I/O operations and allows to use specific I/O 3238 handlers for certain names.</p> 3239 </li> 3240</ul> 3241 3242<p>The general mechanism used when loading http://rpmfind.net/xml.html for 3243example in the HTML parser is the following:</p> 3244<ol> 3245 <li>The default entity loader calls <code>xmlNewInputFromFile()</code> with 3246 the parsing context and the URI string.</li> 3247 <li>the URI string is checked against the existing registered handlers 3248 using their match() callback function, if the HTTP module was compiled 3249 in, it is registered and its match() function will succeeds</li> 3250 <li>the open() function of the handler is called and if successful will 3251 return an I/O Input buffer</li> 3252 <li>the parser will the start reading from this buffer and progressively 3253 fetch information from the resource, calling the read() function of the 3254 handler until the resource is exhausted</li> 3255 <li>if an encoding change is detected it will be installed on the input 3256 buffer, providing buffering and efficient use of the conversion 3257 routines</li> 3258 <li>once the parser has finished, the close() function of the handler is 3259 called once and the Input buffer and associated resources are 3260 deallocated.</li> 3261</ol> 3262 3263<p>The user defined callbacks are checked first to allow overriding of the 3264default libxml2 I/O routines.</p> 3265 3266<h3><a name="basic">The basic buffer type</a></h3> 3267 3268<p>All the buffer manipulation handling is done using the 3269<code>xmlBuffer</code> type define in <code><a 3270href="http://xmlsoft.org/html/libxml-tree.html">tree.h</a> </code>which is a 3271resizable memory buffer. The buffer allocation strategy can be selected to be 3272either best-fit or use an exponential doubling one (CPU vs. memory use 3273trade-off). The values are <code>XML_BUFFER_ALLOC_EXACT</code> and 3274<code>XML_BUFFER_ALLOC_DOUBLEIT</code>, and can be set individually or on a 3275system wide basis using <code>xmlBufferSetAllocationScheme()</code>. A number 3276of functions allows to manipulate buffers with names starting with the 3277<code>xmlBuffer...</code> prefix.</p> 3278 3279<h3><a name="Input">Input I/O handlers</a></h3> 3280 3281<p>An Input I/O handler is a simple structure 3282<code>xmlParserInputBuffer</code> containing a context associated to the 3283resource (file descriptor, or pointer to a protocol handler), the read() and 3284close() callbacks to use and an xmlBuffer. And extra xmlBuffer and a charset 3285encoding handler are also present to support charset conversion when 3286needed.</p> 3287 3288<h3><a name="Output">Output I/O handlers</a></h3> 3289 3290<p>An Output handler <code>xmlOutputBuffer</code> is completely similar to an 3291Input one except the callbacks are write() and close().</p> 3292 3293<h3><a name="entities">The entities loader</a></h3> 3294 3295<p>The entity loader resolves requests for new entities and create inputs for 3296the parser. Creating an input from a filename or an URI string is done 3297through the xmlNewInputFromFile() routine. The default entity loader do not 3298handle the PUBLIC identifier associated with an entity (if any). So it just 3299calls xmlNewInputFromFile() with the SYSTEM identifier (which is mandatory in 3300XML).</p> 3301 3302<p>If you want to hook up a catalog mechanism then you simply need to 3303override the default entity loader, here is an example:</p> 3304<pre>#include <libxml/xmlIO.h> 3305 3306xmlExternalEntityLoader defaultLoader = NULL; 3307 3308xmlParserInputPtr 3309xmlMyExternalEntityLoader(const char *URL, const char *ID, 3310 xmlParserCtxtPtr ctxt) { 3311 xmlParserInputPtr ret; 3312 const char *fileID = NULL; 3313 /* lookup for the fileID depending on ID */ 3314 3315 ret = xmlNewInputFromFile(ctxt, fileID); 3316 if (ret != NULL) 3317 return(ret); 3318 if (defaultLoader != NULL) 3319 ret = defaultLoader(URL, ID, ctxt); 3320 return(ret); 3321} 3322 3323int main(..) { 3324 ... 3325 3326 /* 3327 * Install our own entity loader 3328 */ 3329 defaultLoader = xmlGetExternalEntityLoader(); 3330 xmlSetExternalEntityLoader(xmlMyExternalEntityLoader); 3331 3332 ... 3333}</pre> 3334 3335<h3><a name="Example2">Example of customized I/O</a></h3> 3336 3337<p>This example come from <a href="http://xmlsoft.org/messages/0708.html">a 3338real use case</a>, xmlDocDump() closes the FILE * passed by the application 3339and this was a problem. The <a 3340href="http://xmlsoft.org/messages/0711.html">solution</a> was to redefine a 3341new output handler with the closing call deactivated:</p> 3342<ol> 3343 <li>First define a new I/O output allocator where the output don't close 3344 the file: 3345 <pre>xmlOutputBufferPtr 3346xmlOutputBufferCreateOwn(FILE *file, xmlCharEncodingHandlerPtr encoder) { 3347����xmlOutputBufferPtr ret; 3348���� 3349����if (xmlOutputCallbackInitialized == 0) 3350��������xmlRegisterDefaultOutputCallbacks(); 3351 3352����if (file == NULL) return(NULL); 3353����ret = xmlAllocOutputBuffer(encoder); 3354����if (ret != NULL) { 3355��������ret->context = file; 3356��������ret->writecallback = xmlFileWrite; 3357��������ret->closecallback = NULL; /* No close callback */ 3358����} 3359����return(ret); 3360} </pre> 3361 </li> 3362 <li>And then use it to save the document: 3363 <pre>FILE *f; 3364xmlOutputBufferPtr output; 3365xmlDocPtr doc; 3366int res; 3367 3368f = ... 3369doc = .... 3370 3371output = xmlOutputBufferCreateOwn(f, NULL); 3372res = xmlSaveFileTo(output, doc, NULL); 3373 </pre> 3374 </li> 3375</ol> 3376 3377<h2><a name="Catalog">Catalog support</a></h2> 3378 3379<p>Table of Content:</p> 3380<ol> 3381 <li><a href="General2">General overview</a></li> 3382 <li><a href="#definition">The definition</a></li> 3383 <li><a href="#Simple">Using catalogs</a></li> 3384 <li><a href="#Some">Some examples</a></li> 3385 <li><a href="#reference">How to tune catalog usage</a></li> 3386 <li><a href="#validate">How to debug catalog processing</a></li> 3387 <li><a href="#Declaring">How to create and maintain catalogs</a></li> 3388 <li><a href="#implemento">The implementor corner quick review of the 3389 API</a></li> 3390 <li><a href="#Other">Other resources</a></li> 3391</ol> 3392 3393<h3><a name="General2">General overview</a></h3> 3394 3395<p>What is a catalog? Basically it's a lookup mechanism used when an entity 3396(a file or a remote resource) references another entity. The catalog lookup 3397is inserted between the moment the reference is recognized by the software 3398(XML parser, stylesheet processing, or even images referenced for inclusion 3399in a rendering) and the time where loading that resource is actually 3400started.</p> 3401 3402<p>It is basically used for 3 things:</p> 3403<ul> 3404 <li>mapping from "logical" names, the public identifiers and a more 3405 concrete name usable for download (and URI). For example it can associate 3406 the logical name 3407 <p>"-//OASIS//DTD DocBook XML V4.1.2//EN"</p> 3408 <p>of the DocBook 4.1.2 XML DTD with the actual URL where it can be 3409 downloaded</p> 3410 <p>http://www.oasis-open.org/docbook/xml/4.1.2/docbookx.dtd</p> 3411 </li> 3412 <li>remapping from a given URL to another one, like an HTTP indirection 3413 saying that 3414 <p>"http://www.oasis-open.org/committes/tr.xsl"</p> 3415 <p>should really be looked at</p> 3416 <p>"http://www.oasis-open.org/committes/entity/stylesheets/base/tr.xsl"</p> 3417 </li> 3418 <li>providing a local cache mechanism allowing to load the entities 3419 associated to public identifiers or remote resources, this is a really 3420 important feature for any significant deployment of XML or SGML since it 3421 allows to avoid the aleas and delays associated to fetching remote 3422 resources.</li> 3423</ul> 3424 3425<h3><a name="definition">The definitions</a></h3> 3426 3427<p>Libxml, as of 2.4.3 implements 2 kind of catalogs:</p> 3428<ul> 3429 <li>the older SGML catalogs, the official spec is SGML Open Technical 3430 Resolution TR9401:1997, but is better understood by reading <a 3431 href="http://www.jclark.com/sp/catalog.htm">the SP Catalog page</a> from 3432 James Clark. This is relatively old and not the preferred mode of 3433 operation of libxml.</li> 3434 <li><a href="http://www.oasis-open.org/committees/entity/spec.html">XML 3435 Catalogs</a> is far more flexible, more recent, uses an XML syntax and 3436 should scale quite better. This is the default option of libxml.</li> 3437</ul> 3438 3439<p></p> 3440 3441<h3><a name="Simple">Using catalog</a></h3> 3442 3443<p>In a normal environment libxml2 will by default check the presence of a 3444catalog in /etc/xml/catalog, and assuming it has been correctly populated, 3445the processing is completely transparent to the document user. To take a 3446concrete example, suppose you are authoring a DocBook document, this one 3447starts with the following DOCTYPE definition:</p> 3448<pre><?xml version='1.0'?> 3449<!DOCTYPE book PUBLIC "-//Norman Walsh//DTD DocBk XML V3.1.4//EN" 3450 "http://nwalsh.com/docbook/xml/3.1.4/db3xml.dtd"></pre> 3451 3452<p>When validating the document with libxml, the catalog will be 3453automatically consulted to lookup the public identifier "-//Norman Walsh//DTD 3454DocBk XML V3.1.4//EN" and the system identifier 3455"http://nwalsh.com/docbook/xml/3.1.4/db3xml.dtd", and if these entities have 3456been installed on your system and the catalogs actually point to them, libxml 3457will fetch them from the local disk.</p> 3458 3459<p style="font-size: 10pt"><strong>Note</strong>: Really don't use this 3460DOCTYPE example it's a really old version, but is fine as an example.</p> 3461 3462<p>Libxml2 will check the catalog each time that it is requested to load an 3463entity, this includes DTD, external parsed entities, stylesheets, etc ... If 3464your system is correctly configured all the authoring phase and processing 3465should use only local files, even if your document stays portable because it 3466uses the canonical public and system ID, referencing the remote document.</p> 3467 3468<h3><a name="Some">Some examples:</a></h3> 3469 3470<p>Here is a couple of fragments from XML Catalogs used in libxml2 early 3471regression tests in <code>test/catalogs</code> :</p> 3472<pre><?xml version="1.0"?> 3473<!DOCTYPE catalog PUBLIC 3474 "-//OASIS//DTD Entity Resolution XML Catalog V1.0//EN" 3475 "http://www.oasis-open.org/committees/entity/release/1.0/catalog.dtd"> 3476<catalog xmlns="urn:oasis:names:tc:entity:xmlns:xml:catalog"> 3477 <public publicId="-//OASIS//DTD DocBook XML V4.1.2//EN" 3478 uri="http://www.oasis-open.org/docbook/xml/4.1.2/docbookx.dtd"/> 3479...</pre> 3480 3481<p>This is the beginning of a catalog for DocBook 4.1.2, XML Catalogs are 3482written in XML, there is a specific namespace for catalog elements 3483"urn:oasis:names:tc:entity:xmlns:xml:catalog". The first entry in this 3484catalog is a <code>public</code> mapping it allows to associate a Public 3485Identifier with an URI.</p> 3486<pre>... 3487 <rewriteSystem systemIdStartString="http://www.oasis-open.org/docbook/" 3488 rewritePrefix="file:///usr/share/xml/docbook/"/> 3489...</pre> 3490 3491<p>A <code>rewriteSystem</code> is a very powerful instruction, it says that 3492any URI starting with a given prefix should be looked at another URI 3493constructed by replacing the prefix with an new one. In effect this acts like 3494a cache system for a full area of the Web. In practice it is extremely useful 3495with a file prefix if you have installed a copy of those resources on your 3496local system.</p> 3497<pre>... 3498<delegatePublic publicIdStartString="-//OASIS//DTD XML Catalog //" 3499 catalog="file:///usr/share/xml/docbook.xml"/> 3500<delegatePublic publicIdStartString="-//OASIS//ENTITIES DocBook XML" 3501 catalog="file:///usr/share/xml/docbook.xml"/> 3502<delegatePublic publicIdStartString="-//OASIS//DTD DocBook XML" 3503 catalog="file:///usr/share/xml/docbook.xml"/> 3504<delegateSystem systemIdStartString="http://www.oasis-open.org/docbook/" 3505 catalog="file:///usr/share/xml/docbook.xml"/> 3506<delegateURI uriStartString="http://www.oasis-open.org/docbook/" 3507 catalog="file:///usr/share/xml/docbook.xml"/> 3508...</pre> 3509 3510<p>Delegation is the core features which allows to build a tree of catalogs, 3511easier to maintain than a single catalog, based on Public Identifier, System 3512Identifier or URI prefixes it instructs the catalog software to look up 3513entries in another resource. This feature allow to build hierarchies of 3514catalogs, the set of entries presented should be sufficient to redirect the 3515resolution of all DocBook references to the specific catalog in 3516<code>/usr/share/xml/docbook.xml</code> this one in turn could delegate all 3517references for DocBook 4.2.1 to a specific catalog installed at the same time 3518as the DocBook resources on the local machine.</p> 3519 3520<h3><a name="reference">How to tune catalog usage:</a></h3> 3521 3522<p>The user can change the default catalog behaviour by redirecting queries 3523to its own set of catalogs, this can be done by setting the 3524<code>XML_CATALOG_FILES</code> environment variable to a list of catalogs, an 3525empty one should deactivate loading the default <code>/etc/xml/catalog</code> 3526default catalog</p> 3527 3528<h3><a name="validate">How to debug catalog processing:</a></h3> 3529 3530<p>Setting up the <code>XML_DEBUG_CATALOG</code> environment variable will 3531make libxml2 output debugging informations for each catalog operations, for 3532example:</p> 3533<pre>orchis:~/XML -> xmllint --memory --noout test/ent2 3534warning: failed to load external entity "title.xml" 3535orchis:~/XML -> export XML_DEBUG_CATALOG= 3536orchis:~/XML -> xmllint --memory --noout test/ent2 3537Failed to parse catalog /etc/xml/catalog 3538Failed to parse catalog /etc/xml/catalog 3539warning: failed to load external entity "title.xml" 3540Catalogs cleanup 3541orchis:~/XML -> </pre> 3542 3543<p>The test/ent2 references an entity, running the parser from memory makes 3544the base URI unavailable and the the "title.xml" entity cannot be loaded. 3545Setting up the debug environment variable allows to detect that an attempt is 3546made to load the <code>/etc/xml/catalog</code> but since it's not present the 3547resolution fails.</p> 3548 3549<p>But the most advanced way to debug XML catalog processing is to use the 3550<strong>xmlcatalog</strong> command shipped with libxml2, it allows to load 3551catalogs and make resolution queries to see what is going on. This is also 3552used for the regression tests:</p> 3553<pre>orchis:~/XML -> /xmlcatalog test/catalogs/docbook.xml \ 3554 "-//OASIS//DTD DocBook XML V4.1.2//EN" 3555http://www.oasis-open.org/docbook/xml/4.1.2/docbookx.dtd 3556orchis:~/XML -> </pre> 3557 3558<p>For debugging what is going on, adding one -v flags increase the verbosity 3559level to indicate the processing done (adding a second flag also indicate 3560what elements are recognized at parsing):</p> 3561<pre>orchis:~/XML -> /xmlcatalog -v test/catalogs/docbook.xml \ 3562 "-//OASIS//DTD DocBook XML V4.1.2//EN" 3563Parsing catalog test/catalogs/docbook.xml's content 3564Found public match -//OASIS//DTD DocBook XML V4.1.2//EN 3565http://www.oasis-open.org/docbook/xml/4.1.2/docbookx.dtd 3566Catalogs cleanup 3567orchis:~/XML -> </pre> 3568 3569<p>A shell interface is also available to debug and process multiple queries 3570(and for regression tests):</p> 3571<pre>orchis:~/XML -> /xmlcatalog -shell test/catalogs/docbook.xml \ 3572 "-//OASIS//DTD DocBook XML V4.1.2//EN" 3573> help 3574Commands available: 3575public PublicID: make a PUBLIC identifier lookup 3576system SystemID: make a SYSTEM identifier lookup 3577resolve PublicID SystemID: do a full resolver lookup 3578add 'type' 'orig' 'replace' : add an entry 3579del 'values' : remove values 3580dump: print the current catalog state 3581debug: increase the verbosity level 3582quiet: decrease the verbosity level 3583exit: quit the shell 3584> public "-//OASIS//DTD DocBook XML V4.1.2//EN" 3585http://www.oasis-open.org/docbook/xml/4.1.2/docbookx.dtd 3586> quit 3587orchis:~/XML -> </pre> 3588 3589<p>This should be sufficient for most debugging purpose, this was actually 3590used heavily to debug the XML Catalog implementation itself.</p> 3591 3592<h3><a name="Declaring">How to create and maintain</a> catalogs:</h3> 3593 3594<p>Basically XML Catalogs are XML files, you can either use XML tools to 3595manage them or use <strong>xmlcatalog</strong> for this. The basic step is 3596to create a catalog the -create option provide this facility:</p> 3597<pre>orchis:~/XML -> /xmlcatalog --create tst.xml 3598<?xml version="1.0"?> 3599<!DOCTYPE catalog PUBLIC "-//OASIS//DTD Entity Resolution XML Catalog V1.0//EN" 3600 "http://www.oasis-open.org/committees/entity/release/1.0/catalog.dtd"> 3601<catalog xmlns="urn:oasis:names:tc:entity:xmlns:xml:catalog"/> 3602orchis:~/XML -> </pre> 3603 3604<p>By default xmlcatalog does not overwrite the original catalog and save the 3605result on the standard output, this can be overridden using the -noout 3606option. The <code>-add</code> command allows to add entries in the 3607catalog:</p> 3608<pre>orchis:~/XML -> /xmlcatalog --noout --create --add "public" \ 3609 "-//OASIS//DTD DocBook XML V4.1.2//EN" \ 3610 http://www.oasis-open.org/docbook/xml/4.1.2/docbookx.dtd tst.xml 3611orchis:~/XML -> cat tst.xml 3612<?xml version="1.0"?> 3613<!DOCTYPE catalog PUBLIC "-//OASIS//DTD Entity Resolution XML Catalog V1.0//EN" \ 3614 "http://www.oasis-open.org/committees/entity/release/1.0/catalog.dtd"> 3615<catalog xmlns="urn:oasis:names:tc:entity:xmlns:xml:catalog"> 3616<public publicId="-//OASIS//DTD DocBook XML V4.1.2//EN" 3617 uri="http://www.oasis-open.org/docbook/xml/4.1.2/docbookx.dtd"/> 3618</catalog> 3619orchis:~/XML -> </pre> 3620 3621<p>The <code>-add</code> option will always take 3 parameters even if some of 3622the XML Catalog constructs (like nextCatalog) will have only a single 3623argument, just pass a third empty string, it will be ignored.</p> 3624 3625<p>Similarly the <code>-del</code> option remove matching entries from the 3626catalog:</p> 3627<pre>orchis:~/XML -> /xmlcatalog --del \ 3628 "http://www.oasis-open.org/docbook/xml/4.1.2/docbookx.dtd" tst.xml 3629<?xml version="1.0"?> 3630<!DOCTYPE catalog PUBLIC "-//OASIS//DTD Entity Resolution XML Catalog V1.0//EN" 3631 "http://www.oasis-open.org/committees/entity/release/1.0/catalog.dtd"> 3632<catalog xmlns="urn:oasis:names:tc:entity:xmlns:xml:catalog"/> 3633orchis:~/XML -> </pre> 3634 3635<p>The catalog is now empty. Note that the matching of <code>-del</code> is 3636exact and would have worked in a similar fashion with the Public ID 3637string.</p> 3638 3639<p>This is rudimentary but should be sufficient to manage a not too complex 3640catalog tree of resources.</p> 3641 3642<h3><a name="implemento">The implementor corner quick review of the 3643API:</a></h3> 3644 3645<p>First, and like for every other module of libxml, there is an 3646automatically generated <a href="html/libxml-catalog.html">API page for 3647catalog support</a>.</p> 3648 3649<p>The header for the catalog interfaces should be included as:</p> 3650<pre>#include <libxml/catalog.h></pre> 3651 3652<p>The API is voluntarily kept very simple. First it is not obvious that 3653applications really need access to it since it is the default behaviour of 3654libxml2 (Note: it is possible to completely override libxml2 default catalog 3655by using <a href="html/libxml-parser.html">xmlSetExternalEntityLoader</a> to 3656plug an application specific resolver).</p> 3657 3658<p>Basically libxml2 support 2 catalog lists:</p> 3659<ul> 3660 <li>the default one, global shared by all the application</li> 3661 <li>a per-document catalog, this one is built if the document uses the 3662 <code>oasis-xml-catalog</code> PIs to specify its own catalog list, it is 3663 associated to the parser context and destroyed when the parsing context 3664 is destroyed.</li> 3665</ul> 3666 3667<p>the document one will be used first if it exists.</p> 3668 3669<h4>Initialization routines:</h4> 3670 3671<p>xmlInitializeCatalog(), xmlLoadCatalog() and xmlLoadCatalogs() should be 3672used at startup to initialize the catalog, if the catalog should be 3673initialized with specific values xmlLoadCatalog() or xmlLoadCatalogs() 3674should be called before xmlInitializeCatalog() which would otherwise do a 3675default initialization first.</p> 3676 3677<p>The xmlCatalogAddLocal() call is used by the parser to grow the document 3678own catalog list if needed.</p> 3679 3680<h4>Preferences setup:</h4> 3681 3682<p>The XML Catalog spec requires the possibility to select default 3683preferences between public and system delegation, 3684xmlCatalogSetDefaultPrefer() allows this, xmlCatalogSetDefaults() and 3685xmlCatalogGetDefaults() allow to control if XML Catalogs resolution should 3686be forbidden, allowed for global catalog, for document catalog or both, the 3687default is to allow both.</p> 3688 3689<p>And of course xmlCatalogSetDebug() allows to generate debug messages 3690(through the xmlGenericError() mechanism).</p> 3691 3692<h4>Querying routines:</h4> 3693 3694<p>xmlCatalogResolve(), xmlCatalogResolveSystem(), xmlCatalogResolvePublic() 3695and xmlCatalogResolveURI() are relatively explicit if you read the XML 3696Catalog specification they correspond to section 7 algorithms, they should 3697also work if you have loaded an SGML catalog with a simplified semantic.</p> 3698 3699<p>xmlCatalogLocalResolve() and xmlCatalogLocalResolveURI() are the same but 3700operate on the document catalog list</p> 3701 3702<h4>Cleanup and Miscellaneous:</h4> 3703 3704<p>xmlCatalogCleanup() free-up the global catalog, xmlCatalogFreeLocal() is 3705the per-document equivalent.</p> 3706 3707<p>xmlCatalogAdd() and xmlCatalogRemove() are used to dynamically modify the 3708first catalog in the global list, and xmlCatalogDump() allows to dump a 3709catalog state, those routines are primarily designed for xmlcatalog, I'm not 3710sure that exposing more complex interfaces (like navigation ones) would be 3711really useful.</p> 3712 3713<p>The xmlParseCatalogFile() is a function used to load XML Catalog files, 3714it's similar as xmlParseFile() except it bypass all catalog lookups, it's 3715provided because this functionality may be useful for client tools.</p> 3716 3717<h4>threaded environments:</h4> 3718 3719<p>Since the catalog tree is built progressively, some care has been taken to 3720try to avoid troubles in multithreaded environments. The code is now thread 3721safe assuming that the libxml2 library has been compiled with threads 3722support.</p> 3723 3724<p></p> 3725 3726<h3><a name="Other">Other resources</a></h3> 3727 3728<p>The XML Catalog specification is relatively recent so there isn't much 3729literature to point at:</p> 3730<ul> 3731 <li>You can find a good rant from Norm Walsh about <a 3732 href="http://www.arbortext.com/Think_Tank/XML_Resources/Issue_Three/issue_three.html">the 3733 need for catalogs</a>, it provides a lot of context informations even if 3734 I don't agree with everything presented. Norm also wrote a more recent 3735 article <a 3736 href="http://wwws.sun.com/software/xml/developers/resolver/article/">XML 3737 entities and URI resolvers</a> describing them.</li> 3738 <li>An <a href="http://home.ccil.org/~cowan/XML/XCatalog.html">old XML 3739 catalog proposal</a> from John Cowan</li> 3740 <li>The <a href="http://www.rddl.org/">Resource Directory Description 3741 Language</a> (RDDL) another catalog system but more oriented toward 3742 providing metadata for XML namespaces.</li> 3743 <li>the page from the OASIS Technical <a 3744 href="http://www.oasis-open.org/committees/entity/">Committee on Entity 3745 Resolution</a> who maintains XML Catalog, you will find pointers to the 3746 specification update, some background and pointers to others tools 3747 providing XML Catalog support</li> 3748 <li>There is a <a href="buildDocBookCatalog">shell script</a> to generate 3749 XML Catalogs for DocBook 4.1.2 . If it can write to the /etc/xml/ 3750 directory, it will set-up /etc/xml/catalog and /etc/xml/docbook based on 3751 the resources found on the system. Otherwise it will just create 3752 ~/xmlcatalog and ~/dbkxmlcatalog and doing: 3753 <p><code>export XML_CATALOG_FILES=$HOME/xmlcatalog</code></p> 3754 <p>should allow to process DocBook documentations without requiring 3755 network accesses for the DTD or stylesheets</p> 3756 </li> 3757 <li>I have uploaded <a href="ftp://xmlsoft.org/test/dbk412catalog.tar.gz">a 3758 small tarball</a> containing XML Catalogs for DocBook 4.1.2 which seems 3759 to work fine for me too</li> 3760 <li>The <a href="http://www.xmlsoft.org/xmlcatalog_man.html">xmlcatalog 3761 manual page</a></li> 3762</ul> 3763 3764<p>If you have suggestions for corrections or additions, simply contact 3765me:</p> 3766 3767<h2><a name="library">The parser interfaces</a></h2> 3768 3769<p>This section is directly intended to help programmers getting bootstrapped 3770using the XML tollkit from the C language. It is not intended to be 3771extensive. I hope the automatically generated documents will provide the 3772completeness required, but as a separate set of documents. The interfaces of 3773the XML parser are by principle low level, Those interested in a higher level 3774API should <a href="#DOM">look at DOM</a>.</p> 3775 3776<p>The <a href="html/libxml-parser.html">parser interfaces for XML</a> are 3777separated from the <a href="html/libxml-htmlparser.html">HTML parser 3778interfaces</a>. Let's have a look at how the XML parser can be called:</p> 3779 3780<h3><a name="Invoking">Invoking the parser : the pull method</a></h3> 3781 3782<p>Usually, the first thing to do is to read an XML input. The parser accepts 3783documents either from in-memory strings or from files. The functions are 3784defined in "parser.h":</p> 3785<dl> 3786 <dt><code>xmlDocPtr xmlParseMemory(char *buffer, int size);</code></dt> 3787 <dd><p>Parse a null-terminated string containing the document.</p> 3788 </dd> 3789</dl> 3790<dl> 3791 <dt><code>xmlDocPtr xmlParseFile(const char *filename);</code></dt> 3792 <dd><p>Parse an XML document contained in a (possibly compressed) 3793 file.</p> 3794 </dd> 3795</dl> 3796 3797<p>The parser returns a pointer to the document structure (or NULL in case of 3798failure).</p> 3799 3800<h3 id="Invoking1">Invoking the parser: the push method</h3> 3801 3802<p>In order for the application to keep the control when the document is 3803being fetched (which is common for GUI based programs) libxml2 provides a 3804push interface, too, as of version 1.8.3. Here are the interface 3805functions:</p> 3806<pre>xmlParserCtxtPtr xmlCreatePushParserCtxt(xmlSAXHandlerPtr sax, 3807 void *user_data, 3808 const char *chunk, 3809 int size, 3810 const char *filename); 3811int xmlParseChunk (xmlParserCtxtPtr ctxt, 3812 const char *chunk, 3813 int size, 3814 int terminate);</pre> 3815 3816<p>and here is a simple example showing how to use the interface:</p> 3817<pre> FILE *f; 3818 3819 f = fopen(filename, "r"); 3820 if (f != NULL) { 3821 int res, size = 1024; 3822 char chars[1024]; 3823 xmlParserCtxtPtr ctxt; 3824 3825 res = fread(chars, 1, 4, f); 3826 if (res > 0) { 3827 ctxt = xmlCreatePushParserCtxt(NULL, NULL, 3828 chars, res, filename); 3829 while ((res = fread(chars, 1, size, f)) > 0) { 3830 xmlParseChunk(ctxt, chars, res, 0); 3831 } 3832 xmlParseChunk(ctxt, chars, 0, 1); 3833 doc = ctxt->myDoc; 3834 xmlFreeParserCtxt(ctxt); 3835 } 3836 }</pre> 3837 3838<p>The HTML parser embedded into libxml2 also has a push interface; the 3839functions are just prefixed by "html" rather than "xml".</p> 3840 3841<h3 id="Invoking2">Invoking the parser: the SAX interface</h3> 3842 3843<p>The tree-building interface makes the parser memory-hungry, first loading 3844the document in memory and then building the tree itself. Reading a document 3845without building the tree is possible using the SAX interfaces (see SAX.h and 3846<a href="http://www.daa.com.au/~james/gnome/xml-sax/xml-sax.html">James 3847Henstridge's documentation</a>). Note also that the push interface can be 3848limited to SAX: just use the two first arguments of 3849<code>xmlCreatePushParserCtxt()</code>.</p> 3850 3851<h3><a name="Building">Building a tree from scratch</a></h3> 3852 3853<p>The other way to get an XML tree in memory is by building it. Basically 3854there is a set of functions dedicated to building new elements. (These are 3855also described in <libxml/tree.h>.) For example, here is a piece of 3856code that produces the XML document used in the previous examples:</p> 3857<pre> #include <libxml/tree.h> 3858 xmlDocPtr doc; 3859 xmlNodePtr tree, subtree; 3860 3861 doc = xmlNewDoc("1.0"); 3862 doc->children = xmlNewDocNode(doc, NULL, "EXAMPLE", NULL); 3863 xmlSetProp(doc->children, "prop1", "gnome is great"); 3864 xmlSetProp(doc->children, "prop2", "& linux too"); 3865 tree = xmlNewChild(doc->children, NULL, "head", NULL); 3866 subtree = xmlNewChild(tree, NULL, "title", "Welcome to Gnome"); 3867 tree = xmlNewChild(doc->children, NULL, "chapter", NULL); 3868 subtree = xmlNewChild(tree, NULL, "title", "The Linux adventure"); 3869 subtree = xmlNewChild(tree, NULL, "p", "bla bla bla ..."); 3870 subtree = xmlNewChild(tree, NULL, "image", NULL); 3871 xmlSetProp(subtree, "href", "linus.gif");</pre> 3872 3873<p>Not really rocket science ...</p> 3874 3875<h3><a name="Traversing">Traversing the tree</a></h3> 3876 3877<p>Basically by <a href="html/libxml-tree.html">including "tree.h"</a> your 3878code has access to the internal structure of all the elements of the tree. 3879The names should be somewhat simple like <strong>parent</strong>, 3880<strong>children</strong>, <strong>next</strong>, <strong>prev</strong>, 3881<strong>properties</strong>, etc... For example, still with the previous 3882example:</p> 3883<pre><code>doc->children->children->children</code></pre> 3884 3885<p>points to the title element,</p> 3886<pre>doc->children->children->next->children->children</pre> 3887 3888<p>points to the text node containing the chapter title "The Linux 3889adventure".</p> 3890 3891<p><strong>NOTE</strong>: XML allows <em>PI</em>s and <em>comments</em> to be 3892present before the document root, so <code>doc->children</code> may point 3893to an element which is not the document Root Element; a function 3894<code>xmlDocGetRootElement()</code> was added for this purpose.</p> 3895 3896<h3><a name="Modifying">Modifying the tree</a></h3> 3897 3898<p>Functions are provided for reading and writing the document content. Here 3899is an excerpt from the <a href="html/libxml-tree.html">tree API</a>:</p> 3900<dl> 3901 <dt><code>xmlAttrPtr xmlSetProp(xmlNodePtr node, const xmlChar *name, const 3902 xmlChar *value);</code></dt> 3903 <dd><p>This sets (or changes) an attribute carried by an ELEMENT node. 3904 The value can be NULL.</p> 3905 </dd> 3906</dl> 3907<dl> 3908 <dt><code>const xmlChar *xmlGetProp(xmlNodePtr node, const xmlChar 3909 *name);</code></dt> 3910 <dd><p>This function returns a pointer to new copy of the property 3911 content. Note that the user must deallocate the result.</p> 3912 </dd> 3913</dl> 3914 3915<p>Two functions are provided for reading and writing the text associated 3916with elements:</p> 3917<dl> 3918 <dt><code>xmlNodePtr xmlStringGetNodeList(xmlDocPtr doc, const xmlChar 3919 *value);</code></dt> 3920 <dd><p>This function takes an "external" string and converts it to one 3921 text node or possibly to a list of entity and text nodes. All 3922 non-predefined entity references like &Gnome; will be stored 3923 internally as entity nodes, hence the result of the function may not be 3924 a single node.</p> 3925 </dd> 3926</dl> 3927<dl> 3928 <dt><code>xmlChar *xmlNodeListGetString(xmlDocPtr doc, xmlNodePtr list, int 3929 inLine);</code></dt> 3930 <dd><p>This function is the inverse of 3931 <code>xmlStringGetNodeList()</code>. It generates a new string 3932 containing the content of the text and entity nodes. Note the extra 3933 argument inLine. If this argument is set to 1, the function will expand 3934 entity references. For example, instead of returning the &Gnome; 3935 XML encoding in the string, it will substitute it with its value (say, 3936 "GNU Network Object Model Environment").</p> 3937 </dd> 3938</dl> 3939 3940<h3><a name="Saving">Saving a tree</a></h3> 3941 3942<p>Basically 3 options are possible:</p> 3943<dl> 3944 <dt><code>void xmlDocDumpMemory(xmlDocPtr cur, xmlChar**mem, int 3945 *size);</code></dt> 3946 <dd><p>Returns a buffer into which the document has been saved.</p> 3947 </dd> 3948</dl> 3949<dl> 3950 <dt><code>extern void xmlDocDump(FILE *f, xmlDocPtr doc);</code></dt> 3951 <dd><p>Dumps a document to an open file descriptor.</p> 3952 </dd> 3953</dl> 3954<dl> 3955 <dt><code>int xmlSaveFile(const char *filename, xmlDocPtr cur);</code></dt> 3956 <dd><p>Saves the document to a file. In this case, the compression 3957 interface is triggered if it has been turned on.</p> 3958 </dd> 3959</dl> 3960 3961<h3><a name="Compressio">Compression</a></h3> 3962 3963<p>The library transparently handles compression when doing file-based 3964accesses. The level of compression on saves can be turned on either globally 3965or individually for one file:</p> 3966<dl> 3967 <dt><code>int xmlGetDocCompressMode (xmlDocPtr doc);</code></dt> 3968 <dd><p>Gets the document compression ratio (0-9).</p> 3969 </dd> 3970</dl> 3971<dl> 3972 <dt><code>void xmlSetDocCompressMode (xmlDocPtr doc, int mode);</code></dt> 3973 <dd><p>Sets the document compression ratio.</p> 3974 </dd> 3975</dl> 3976<dl> 3977 <dt><code>int xmlGetCompressMode(void);</code></dt> 3978 <dd><p>Gets the default compression ratio.</p> 3979 </dd> 3980</dl> 3981<dl> 3982 <dt><code>void xmlSetCompressMode(int mode);</code></dt> 3983 <dd><p>Sets the default compression ratio.</p> 3984 </dd> 3985</dl> 3986 3987<h2><a name="Entities">Entities or no entities</a></h2> 3988 3989<p>Entities in principle are similar to simple C macros. An entity defines an 3990abbreviation for a given string that you can reuse many times throughout the 3991content of your document. Entities are especially useful when a given string 3992may occur frequently within a document, or to confine the change needed to a 3993document to a restricted area in the internal subset of the document (at the 3994beginning). Example:</p> 3995<pre>1 <?xml version="1.0"?> 39962 <!DOCTYPE EXAMPLE SYSTEM "example.dtd" [ 39973 <!ENTITY xml "Extensible Markup Language"> 39984 ]> 39995 <EXAMPLE> 40006 &xml; 40017 </EXAMPLE></pre> 4002 4003<p>Line 3 declares the xml entity. Line 6 uses the xml entity, by prefixing 4004its name with '&' and following it by ';' without any spaces added. There 4005are 5 predefined entities in libxml2 allowing you to escape characters with 4006predefined meaning in some parts of the xml document content: 4007<strong>&lt;</strong> for the character '<', <strong>&gt;</strong> 4008for the character '>', <strong>&apos;</strong> for the character ''', 4009<strong>&quot;</strong> for the character '"', and 4010<strong>&amp;</strong> for the character '&'.</p> 4011 4012<p>One of the problems related to entities is that you may want the parser to 4013substitute an entity's content so that you can see the replacement text in 4014your application. Or you may prefer to keep entity references as such in the 4015content to be able to save the document back without losing this usually 4016precious information (if the user went through the pain of explicitly 4017defining entities, he may have a a rather negative attitude if you blindly 4018substitute them as saving time). The <a 4019href="html/libxml-parser.html#xmlSubstituteEntitiesDefault">xmlSubstituteEntitiesDefault()</a> 4020function allows you to check and change the behaviour, which is to not 4021substitute entities by default.</p> 4022 4023<p>Here is the DOM tree built by libxml2 for the previous document in the 4024default case:</p> 4025<pre>/gnome/src/gnome-xml -> /xmllint --debug test/ent1 4026DOCUMENT 4027version=1.0 4028 ELEMENT EXAMPLE 4029 TEXT 4030 content= 4031 ENTITY_REF 4032 INTERNAL_GENERAL_ENTITY xml 4033 content=Extensible Markup Language 4034 TEXT 4035 content=</pre> 4036 4037<p>And here is the result when substituting entities:</p> 4038<pre>/gnome/src/gnome-xml -> /tester --debug --noent test/ent1 4039DOCUMENT 4040version=1.0 4041 ELEMENT EXAMPLE 4042 TEXT 4043 content= Extensible Markup Language</pre> 4044 4045<p>So, entities or no entities? Basically, it depends on your use case. I 4046suggest that you keep the non-substituting default behaviour and avoid using 4047entities in your XML document or data if you are not willing to handle the 4048entity references elements in the DOM tree.</p> 4049 4050<p>Note that at save time libxml2 enforces the conversion of the predefined 4051entities where necessary to prevent well-formedness problems, and will also 4052transparently replace those with chars (i.e. it will not generate entity 4053reference elements in the DOM tree or call the reference() SAX callback when 4054finding them in the input).</p> 4055 4056<p><span style="background-color: #FF0000">WARNING</span>: handling entities 4057on top of the libxml2 SAX interface is difficult!!! If you plan to use 4058non-predefined entities in your documents, then the learning curve to handle 4059then using the SAX API may be long. If you plan to use complex documents, I 4060strongly suggest you consider using the DOM interface instead and let libxml 4061deal with the complexity rather than trying to do it yourself.</p> 4062 4063<h2><a name="Namespaces">Namespaces</a></h2> 4064 4065<p>The libxml2 library implements <a 4066href="http://www.w3.org/TR/REC-xml-names/">XML namespaces</a> support by 4067recognizing namespace constructs in the input, and does namespace lookup 4068automatically when building the DOM tree. A namespace declaration is 4069associated with an in-memory structure and all elements or attributes within 4070that namespace point to it. Hence testing the namespace is a simple and fast 4071equality operation at the user level.</p> 4072 4073<p>I suggest that people using libxml2 use a namespace, and declare it in the 4074root element of their document as the default namespace. Then they don't need 4075to use the prefix in the content but we will have a basis for future semantic 4076refinement and merging of data from different sources. This doesn't increase 4077the size of the XML output significantly, but significantly increases its 4078value in the long-term. Example:</p> 4079<pre><mydoc xmlns="http://mydoc.example.org/schemas/"> 4080 <elem1>...</elem1> 4081 <elem2>...</elem2> 4082</mydoc></pre> 4083 4084<p>The namespace value has to be an absolute URL, but the URL doesn't have to 4085point to any existing resource on the Web. It will bind all the element and 4086attributes with that URL. I suggest to use an URL within a domain you 4087control, and that the URL should contain some kind of version information if 4088possible. For example, <code>"http://www.gnome.org/gnumeric/1.0/"</code> is a 4089good namespace scheme.</p> 4090 4091<p>Then when you load a file, make sure that a namespace carrying the 4092version-independent prefix is installed on the root element of your document, 4093and if the version information don't match something you know, warn the user 4094and be liberal in what you accept as the input. Also do *not* try to base 4095namespace checking on the prefix value. <foo:text> may be exactly the 4096same as <bar:text> in another document. What really matters is the URI 4097associated with the element or the attribute, not the prefix string (which is 4098just a shortcut for the full URI). In libxml, element and attributes have an 4099<code>ns</code> field pointing to an xmlNs structure detailing the namespace 4100prefix and its URI.</p> 4101 4102<p>@@Interfaces@@</p> 4103<pre>xmlNodePtr node; 4104if(!strncmp(node->name,"mytag",5) 4105 && node->ns 4106 && !strcmp(node->ns->href,"http://www.mysite.com/myns/1.0")) { 4107 ... 4108}</pre> 4109 4110<p>Usually people object to using namespaces together with validity checking. 4111I will try to make sure that using namespaces won't break validity checking, 4112so even if you plan to use or currently are using validation I strongly 4113suggest adding namespaces to your document. A default namespace scheme 4114<code>xmlns="http://...."</code> should not break validity even on less 4115flexible parsers. Using namespaces to mix and differentiate content coming 4116from multiple DTDs will certainly break current validation schemes. To check 4117such documents one needs to use schema-validation, which is supported in 4118libxml2 as well. See <a href="http://www.relaxng.org/">relagx-ng</a> and <a 4119href="http://www.w3c.org/XML/Schema">w3c-schema</a>.</p> 4120 4121<h2><a name="Upgrading">Upgrading 1.x code</a></h2> 4122 4123<p>Incompatible changes:</p> 4124 4125<p>Version 2 of libxml2 is the first version introducing serious backward 4126incompatible changes. The main goals were:</p> 4127<ul> 4128 <li>a general cleanup. A number of mistakes inherited from the very early 4129 versions couldn't be changed due to compatibility constraints. Example 4130 the "childs" element in the nodes.</li> 4131 <li>Uniformization of the various nodes, at least for their header and link 4132 parts (doc, parent, children, prev, next), the goal is a simpler 4133 programming model and simplifying the task of the DOM implementors.</li> 4134 <li>better conformances to the XML specification, for example version 1.x 4135 had an heuristic to try to detect ignorable white spaces. As a result the 4136 SAX event generated were ignorableWhitespace() while the spec requires 4137 character() in that case. This also mean that a number of DOM node 4138 containing blank text may populate the DOM tree which were not present 4139 before.</li> 4140</ul> 4141 4142<h3>How to fix libxml-1.x code:</h3> 4143 4144<p>So client code of libxml designed to run with version 1.x may have to be 4145changed to compile against version 2.x of libxml. Here is a list of changes 4146that I have collected, they may not be sufficient, so in case you find other 4147change which are required, <a href="mailto:Daniel.Veillard@w3.org">drop me a 4148mail</a>:</p> 4149<ol> 4150 <li>The package name have changed from libxml to libxml2, the library name 4151 is now -lxml2 . There is a new xml2-config script which should be used to 4152 select the right parameters libxml2</li> 4153 <li>Node <strong>childs</strong> field has been renamed 4154 <strong>children</strong> so s/childs/children/g should be applied 4155 (probability of having "childs" anywhere else is close to 0+</li> 4156 <li>The document don't have anymore a <strong>root</strong> element it has 4157 been replaced by <strong>children</strong> and usually you will get a 4158 list of element here. For example a Dtd element for the internal subset 4159 and it's declaration may be found in that list, as well as processing 4160 instructions or comments found before or after the document root element. 4161 Use <strong>xmlDocGetRootElement(doc)</strong> to get the root element of 4162 a document. Alternatively if you are sure to not reference DTDs nor have 4163 PIs or comments before or after the root element 4164 s/->root/->children/g will probably do it.</li> 4165 <li>The white space issue, this one is more complex, unless special case of 4166 validating parsing, the line breaks and spaces usually used for indenting 4167 and formatting the document content becomes significant. So they are 4168 reported by SAX and if your using the DOM tree, corresponding nodes are 4169 generated. Too approach can be taken: 4170 <ol> 4171 <li>lazy one, use the compatibility call 4172 <strong>xmlKeepBlanksDefault(0)</strong> but be aware that you are 4173 relying on a special (and possibly broken) set of heuristics of 4174 libxml to detect ignorable blanks. Don't complain if it breaks or 4175 make your application not 100% clean w.r.t. to it's input.</li> 4176 <li>the Right Way: change you code to accept possibly insignificant 4177 blanks characters, or have your tree populated with weird blank text 4178 nodes. You can spot them using the commodity function 4179 <strong>xmlIsBlankNode(node)</strong> returning 1 for such blank 4180 nodes.</li> 4181 </ol> 4182 <p>Note also that with the new default the output functions don't add any 4183 extra indentation when saving a tree in order to be able to round trip 4184 (read and save) without inflating the document with extra formatting 4185 chars.</p> 4186 </li> 4187 <li>The include path has changed to $prefix/libxml/ and the includes 4188 themselves uses this new prefix in includes instructions... If you are 4189 using (as expected) the 4190 <pre>xml2-config --cflags</pre> 4191 <p>output to generate you compile commands this will probably work out of 4192 the box</p> 4193 </li> 4194 <li>xmlDetectCharEncoding takes an extra argument indicating the length in 4195 byte of the head of the document available for character detection.</li> 4196</ol> 4197 4198<h3>Ensuring both libxml-1.x and libxml-2.x compatibility</h3> 4199 4200<p>Two new version of libxml (1.8.11) and libxml2 (2.3.4) have been released 4201to allow smooth upgrade of existing libxml v1code while retaining 4202compatibility. They offers the following:</p> 4203<ol> 4204 <li>similar include naming, one should use 4205 <strong>#include<libxml/...></strong> in both cases.</li> 4206 <li>similar identifiers defined via macros for the child and root fields: 4207 respectively <strong>xmlChildrenNode</strong> and 4208 <strong>xmlRootNode</strong></li> 4209 <li>a new macro <strong>LIBXML_TEST_VERSION</strong> which should be 4210 inserted once in the client code</li> 4211</ol> 4212 4213<p>So the roadmap to upgrade your existing libxml applications is the 4214following:</p> 4215<ol> 4216 <li>install the libxml-1.8.8 (and libxml-devel-1.8.8) packages</li> 4217 <li>find all occurrences where the xmlDoc <strong>root</strong> field is 4218 used and change it to <strong>xmlRootNode</strong></li> 4219 <li>similarly find all occurrences where the xmlNode 4220 <strong>childs</strong> field is used and change it to 4221 <strong>xmlChildrenNode</strong></li> 4222 <li>add a <strong>LIBXML_TEST_VERSION</strong> macro somewhere in your 4223 <strong>main()</strong> or in the library init entry point</li> 4224 <li>Recompile, check compatibility, it should still work</li> 4225 <li>Change your configure script to look first for xml2-config and fall 4226 back using xml-config . Use the --cflags and --libs output of the command 4227 as the Include and Linking parameters needed to use libxml.</li> 4228 <li>install libxml2-2.3.x and libxml2-devel-2.3.x (libxml-1.8.y and 4229 libxml-devel-1.8.y can be kept simultaneously)</li> 4230 <li>remove your config.cache, relaunch your configuration mechanism, and 4231 recompile, if steps 2 and 3 were done right it should compile as-is</li> 4232 <li>Test that your application is still running correctly, if not this may 4233 be due to extra empty nodes due to formating spaces being kept in libxml2 4234 contrary to libxml1, in that case insert xmlKeepBlanksDefault(1) in your 4235 code before calling the parser (next to 4236 <strong>LIBXML_TEST_VERSION</strong> is a fine place).</li> 4237</ol> 4238 4239<p>Following those steps should work. It worked for some of my own code.</p> 4240 4241<p>Let me put some emphasis on the fact that there is far more changes from 4242libxml 1.x to 2.x than the ones you may have to patch for. The overall code 4243has been considerably cleaned up and the conformance to the XML specification 4244has been drastically improved too. Don't take those changes as an excuse to 4245not upgrade, it may cost a lot on the long term ...</p> 4246 4247<h2><a name="Thread">Thread safety</a></h2> 4248 4249<p>Starting with 2.4.7, libxml2 makes provisions to ensure that concurrent 4250threads can safely work in parallel parsing different documents. There is 4251however a couple of things to do to ensure it:</p> 4252<ul> 4253 <li>configure the library accordingly using the --with-threads options</li> 4254 <li>call xmlInitParser() in the "main" thread before using any of the 4255 libxml2 API (except possibly selecting a different memory allocator)</li> 4256</ul> 4257 4258<p>Note that the thread safety cannot be ensured for multiple threads sharing 4259the same document, the locking must be done at the application level, libxml 4260exports a basic mutex and reentrant mutexes API in <libxml/threads.h>. 4261The parts of the library checked for thread safety are:</p> 4262<ul> 4263 <li>concurrent loading</li> 4264 <li>file access resolution</li> 4265 <li>catalog access</li> 4266 <li>catalog building</li> 4267 <li>entities lookup/accesses</li> 4268 <li>validation</li> 4269 <li>global variables per-thread override</li> 4270 <li>memory handling</li> 4271</ul> 4272 4273<p>XPath is supposed to be thread safe now, but this wasn't tested 4274seriously.</p> 4275 4276<h2><a name="DOM"></a><a name="Principles">DOM Principles</a></h2> 4277 4278<p><a href="http://www.w3.org/DOM/">DOM</a> stands for the <em>Document 4279Object Model</em>; this is an API for accessing XML or HTML structured 4280documents. Native support for DOM in Gnome is on the way (module gnome-dom), 4281and will be based on gnome-xml. This will be a far cleaner interface to 4282manipulate XML files within Gnome since it won't expose the internal 4283structure.</p> 4284 4285<p>The current DOM implementation on top of libxml2 is the <a 4286href="http://cvs.gnome.org/lxr/source/gdome2/">gdome2 Gnome module</a>, this 4287is a full DOM interface, thanks to Paolo Casarini, check the <a 4288href="http://www.cs.unibo.it/~casarini/gdome2/">Gdome2 homepage</a> for more 4289informations.</p> 4290 4291<h2><a name="Example"></a><a name="real">A real example</a></h2> 4292 4293<p>Here is a real size example, where the actual content of the application 4294data is not kept in the DOM tree but uses internal structures. It is based on 4295a proposal to keep a database of jobs related to Gnome, with an XML based 4296storage structure. Here is an <a href="gjobs.xml">XML encoded jobs 4297base</a>:</p> 4298<pre><?xml version="1.0"?> 4299<gjob:Helping xmlns:gjob="http://www.gnome.org/some-location"> 4300 <gjob:Jobs> 4301 4302 <gjob:Job> 4303 <gjob:Project ID="3"/> 4304 <gjob:Application>GBackup</gjob:Application> 4305 <gjob:Category>Development</gjob:Category> 4306 4307 <gjob:Update> 4308 <gjob:Status>Open</gjob:Status> 4309 <gjob:Modified>Mon, 07 Jun 1999 20:27:45 -0400 MET DST</gjob:Modified> 4310 <gjob:Salary>USD 0.00</gjob:Salary> 4311 </gjob:Update> 4312 4313 <gjob:Developers> 4314 <gjob:Developer> 4315 </gjob:Developer> 4316 </gjob:Developers> 4317 4318 <gjob:Contact> 4319 <gjob:Person>Nathan Clemons</gjob:Person> 4320 <gjob:Email>nathan@windsofstorm.net</gjob:Email> 4321 <gjob:Company> 4322 </gjob:Company> 4323 <gjob:Organisation> 4324 </gjob:Organisation> 4325 <gjob:Webpage> 4326 </gjob:Webpage> 4327 <gjob:Snailmail> 4328 </gjob:Snailmail> 4329 <gjob:Phone> 4330 </gjob:Phone> 4331 </gjob:Contact> 4332 4333 <gjob:Requirements> 4334 The program should be released as free software, under the GPL. 4335 </gjob:Requirements> 4336 4337 <gjob:Skills> 4338 </gjob:Skills> 4339 4340 <gjob:Details> 4341 A GNOME based system that will allow a superuser to configure 4342 compressed and uncompressed files and/or file systems to be backed 4343 up with a supported media in the system. This should be able to 4344 perform via find commands generating a list of files that are passed 4345 to tar, dd, cpio, cp, gzip, etc., to be directed to the tape machine 4346 or via operations performed on the filesystem itself. Email 4347 notification and GUI status display very important. 4348 </gjob:Details> 4349 4350 </gjob:Job> 4351 4352 </gjob:Jobs> 4353</gjob:Helping></pre> 4354 4355<p>While loading the XML file into an internal DOM tree is a matter of 4356calling only a couple of functions, browsing the tree to gather the data and 4357generate the internal structures is harder, and more error prone.</p> 4358 4359<p>The suggested principle is to be tolerant with respect to the input 4360structure. For example, the ordering of the attributes is not significant, 4361the XML specification is clear about it. It's also usually a good idea not to 4362depend on the order of the children of a given node, unless it really makes 4363things harder. Here is some code to parse the information for a person:</p> 4364<pre>/* 4365 * A person record 4366 */ 4367typedef struct person { 4368 char *name; 4369 char *email; 4370 char *company; 4371 char *organisation; 4372 char *smail; 4373 char *webPage; 4374 char *phone; 4375} person, *personPtr; 4376 4377/* 4378 * And the code needed to parse it 4379 */ 4380personPtr parsePerson(xmlDocPtr doc, xmlNsPtr ns, xmlNodePtr cur) { 4381 personPtr ret = NULL; 4382 4383DEBUG("parsePerson\n"); 4384 /* 4385 * allocate the struct 4386 */ 4387 ret = (personPtr) malloc(sizeof(person)); 4388 if (ret == NULL) { 4389 fprintf(stderr,"out of memory\n"); 4390 return(NULL); 4391 } 4392 memset(ret, 0, sizeof(person)); 4393 4394 /* We don't care what the top level element name is */ 4395 cur = cur->xmlChildrenNode; 4396 while (cur != NULL) { 4397 if ((!strcmp(cur->name, "Person")) && (cur->ns == ns)) 4398 ret->name = xmlNodeListGetString(doc, cur->xmlChildrenNode, 1); 4399 if ((!strcmp(cur->name, "Email")) && (cur->ns == ns)) 4400 ret->email = xmlNodeListGetString(doc, cur->xmlChildrenNode, 1); 4401 cur = cur->next; 4402 } 4403 4404 return(ret); 4405}</pre> 4406 4407<p>Here are a couple of things to notice:</p> 4408<ul> 4409 <li>Usually a recursive parsing style is the more convenient one: XML data 4410 is by nature subject to repetitive constructs and usually exhibits highly 4411 structured patterns.</li> 4412 <li>The two arguments of type <em>xmlDocPtr</em> and <em>xmlNsPtr</em>, 4413 i.e. the pointer to the global XML document and the namespace reserved to 4414 the application. Document wide information are needed for example to 4415 decode entities and it's a good coding practice to define a namespace for 4416 your application set of data and test that the element and attributes 4417 you're analyzing actually pertains to your application space. This is 4418 done by a simple equality test (cur->ns == ns).</li> 4419 <li>To retrieve text and attributes value, you can use the function 4420 <em>xmlNodeListGetString</em> to gather all the text and entity reference 4421 nodes generated by the DOM output and produce an single text string.</li> 4422</ul> 4423 4424<p>Here is another piece of code used to parse another level of the 4425structure:</p> 4426<pre>#include <libxml/tree.h> 4427/* 4428 * a Description for a Job 4429 */ 4430typedef struct job { 4431 char *projectID; 4432 char *application; 4433 char *category; 4434 personPtr contact; 4435 int nbDevelopers; 4436 personPtr developers[100]; /* using dynamic alloc is left as an exercise */ 4437} job, *jobPtr; 4438 4439/* 4440 * And the code needed to parse it 4441 */ 4442jobPtr parseJob(xmlDocPtr doc, xmlNsPtr ns, xmlNodePtr cur) { 4443 jobPtr ret = NULL; 4444 4445DEBUG("parseJob\n"); 4446 /* 4447 * allocate the struct 4448 */ 4449 ret = (jobPtr) malloc(sizeof(job)); 4450 if (ret == NULL) { 4451 fprintf(stderr,"out of memory\n"); 4452 return(NULL); 4453 } 4454 memset(ret, 0, sizeof(job)); 4455 4456 /* We don't care what the top level element name is */ 4457 cur = cur->xmlChildrenNode; 4458 while (cur != NULL) { 4459 4460 if ((!strcmp(cur->name, "Project")) && (cur->ns == ns)) { 4461 ret->projectID = xmlGetProp(cur, "ID"); 4462 if (ret->projectID == NULL) { 4463 fprintf(stderr, "Project has no ID\n"); 4464 } 4465 } 4466 if ((!strcmp(cur->name, "Application")) && (cur->ns == ns)) 4467 ret->application = xmlNodeListGetString(doc, cur->xmlChildrenNode, 1); 4468 if ((!strcmp(cur->name, "Category")) && (cur->ns == ns)) 4469 ret->category = xmlNodeListGetString(doc, cur->xmlChildrenNode, 1); 4470 if ((!strcmp(cur->name, "Contact")) && (cur->ns == ns)) 4471 ret->contact = parsePerson(doc, ns, cur); 4472 cur = cur->next; 4473 } 4474 4475 return(ret); 4476}</pre> 4477 4478<p>Once you are used to it, writing this kind of code is quite simple, but 4479boring. Ultimately, it could be possible to write stubbers taking either C 4480data structure definitions, a set of XML examples or an XML DTD and produce 4481the code needed to import and export the content between C data and XML 4482storage. This is left as an exercise to the reader :-)</p> 4483 4484<p>Feel free to use <a href="example/gjobread.c">the code for the full C 4485parsing example</a> as a template, it is also available with Makefile in the 4486Gnome CVS base under gnome-xml/example</p> 4487 4488<h2><a name="Contributi">Contributions</a></h2> 4489<ul> 4490 <li>Bjorn Reese, William Brack and Thomas Broyer have provided a number of 4491 patches, Gary Pennington worked on the validation API, threading support 4492 and Solaris port.</li> 4493 <li>John Fleck helps maintaining the documentation and man pages.</li> 4494 <li><a href="mailto:igor@zlatkovic.com">Igor Zlatkovic</a> is now the 4495 maintainer of the Windows port, <a 4496 href="http://www.zlatkovic.com/projects/libxml/index.html">he provides 4497 binaries</a></li> 4498 <li><a href="mailto:Gary.Pennington@sun.com">Gary Pennington</a> provides 4499 <a href="http://garypennington.net/libxml2/">Solaris binaries</a></li> 4500 <li><a 4501 href="http://mail.gnome.org/archives/xml/2001-March/msg00014.html">Matt 4502 Sergeant</a> developed <a 4503 href="http://axkit.org/download/">XML::LibXSLT</a>, a Perl wrapper for 4504 libxml2/libxslt as part of the <a href="http://axkit.com/">AxKit XML 4505 application server</a></li> 4506 <li><a href="mailto:fnatter@gmx.net">Felix Natter</a> and <a 4507 href="mailto:geertk@ai.rug.nl">Geert Kloosterman</a> provide <a 4508 href="libxml-doc.el">an emacs module</a> to lookup libxml(2) functions 4509 documentation</li> 4510 <li><a href="mailto:sherwin@nlm.nih.gov">Ziying Sherwin</a> provided <a 4511 href="http://xmlsoft.org/messages/0488.html">man pages</a></li> 4512 <li>there is a module for <a 4513 href="http://acs-misc.sourceforge.net/nsxml.html">libxml/libxslt support 4514 in OpenNSD/AOLServer</a></li> 4515 <li><a href="mailto:dkuhlman@cutter.rexx.com">Dave Kuhlman</a> provided the 4516 first version of libxml/libxslt <a 4517 href="http://www.rexx.com/~dkuhlman">wrappers for Python</a></li> 4518 <li>Petr Kozelka provides <a 4519 href="http://sourceforge.net/projects/libxml2-pas">Pascal units to glue 4520 libxml2</a> with Kylix and Delphi and other Pascal compilers</li> 4521 <li><a href="mailto:aleksey@aleksey.com">Aleksey Sanin</a> implemented the 4522 <a href="http://www.w3.org/Signature/">XML Canonicalization and XML 4523 Digital Signature</a> <a 4524 href="http://www.aleksey.com/xmlsec/">implementations for libxml2</a></li> 4525 <li><a href="mailto:Steve.Ball@zveno.com">Steve Ball</a>, <a 4526 href="http://www.zveno.com/">Zveno</a> and contributors maintain <a 4527 href="http://tclxml.sourceforge.net/">tcl bindings for libxml2 and 4528 libxslt</a>, as well as <a 4529 href="http://tclxml.sf.net/tkxmllint.html">tkxmllint</a> a GUI for 4530 xmllint and <a href="http://tclxml.sf.net/tkxsltproc.html">tkxsltproc</a> 4531 a GUI for xsltproc.</li> 4532</ul> 4533 4534<p></p> 4535</body> 4536</html> 4537
