xml.html revision 0d1a845097fa0e224a2712b3c5c5380dd64f3fa7
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</ul> 77 78<p>In most cases libxml2 tries to implement the specifications in a 79relatively strictly compliant way. As of release 2.4.16, libxml2 passes all 801800+ tests from the <a 81href="http://www.oasis-open.org/committees/xml-conformance/">OASIS XML Tests 82Suite</a>.</p> 83 84<p>To some extent libxml2 provides support for the following additional 85specifications but doesn't claim to implement them completely:</p> 86<ul> 87 <li>Document Object Model (DOM) <a 88 href="http://www.w3.org/TR/DOM-Level-2-Core/">http://www.w3.org/TR/DOM-Level-2-Core/</a> 89 it doesn't implement the API itself, gdome2 does this on top of 90 libxml2</li> 91 <li><a href="http://www.cis.ohio-state.edu/rfc/rfc959.txt">RFC 959</a> : 92 libxml2 implements a basic FTP client code</li> 93 <li><a href="http://www.cis.ohio-state.edu/rfc/rfc1945.txt">RFC 1945</a> : 94 HTTP/1.0, again a basic HTTP client code</li> 95 <li>SAX: a minimal SAX implementation compatible with early expat 96 versions</li> 97 <li>DocBook SGML v4: libxml2 includes a hackish parser to transition to 98 XML</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 ( 604<a href="http://xmlsoft.org/sources/">HTTP</a>, 605<a href="ftp://xmlsoft.org/">FTP</a> and rsync are 606available), there is also mirrors (<a 607href="ftp://speakeasy.rpmfind.net/pub/libxml/">Seattle</a>, <a 608href="ftp://fr.rpmfind.net/pub/libxml/">France</a>) or on the <a 609href="ftp://ftp.gnome.org/pub/GNOME/MIRRORS.html">Gnome FTP server</a> as <a 610href="ftp://ftp.gnome.org/pub/GNOME/sources/libxml2/2.6/">source archive</a> 611, Antonin Sprinzl also provide <a href="ftp://gd.tuwien.ac.at/pub/libxml/">a 612mirror in Austria</a>. (NOTE that you need both the <a 613href="http://rpmfind.net/linux/RPM/libxml2.html">libxml(2)</a> and <a 614href="http://rpmfind.net/linux/RPM/libxml2-devel.html">libxml(2)-devel</a> 615packages installed to compile applications using libxml.)</p> 616<p> You can find all the history of libxml(2) and libxslt releases 617in the <a href="http://xmlsoft.org/sources/old/">old</a> directory.</p> 618 619<p>Binary ports:</p> 620<ul> 621 <li>Red Hat RPMs for i386 are available directly on <a 622 href="ftp://xmlsoft.org/">xmlsoft.org</a>, the source RPM will compile on 623 any architecture supported by Red Hat.</li> 624 <li><p><a href="mailto:igor@zlatkovic.com">Igor Zlatkovic</a></p> 625 is now the maintainer of the Windows port, <a 626 href="http://www.zlatkovic.com/projects/libxml/index.html">he provides 627 binaries</a>.</li> 628 <li><a href="mailto:Gary.Pennington@sun.com">Gary Pennington</a> provides 629 <a href="http://garypennington.net/libxml2/">Solaris binaries</a>.</li> 630 <li><a href="mailto:Steve.Ball@zveno.com">Steve Ball</a> provides <a 631 href="http://www.zveno.com/open_source/libxml2xslt.html">Mac Os X 632 binaries</a>.</li> 633 <li>The HP-UX porting center provides <a 634 href="http://hpux.connect.org.uk/hppd/hpux/Gnome/">HP-UX binaries</a></li> 635</ul> 636 637<p>If you know other supported binary ports, please <a 638href="http://veillard.com/">contact me</a>.</p> 639 640<p><a name="Snapshot">Snapshot:</a></p> 641<ul> 642 <li>Code from the W3C cvs base gnome-xml <a 643 href="ftp://xmlsoft.org/cvs-snapshot.tar.gz">cvs-snapshot.tar.gz</a>.</li> 644 <li>Docs, content of the web site, the list archive included <a 645 href="ftp://xmlsoft.org/libxml-docs.tar.gz">libxml-docs.tar.gz</a>.</li> 646</ul> 647 648<p><a name="Contribs">Contributions:</a></p> 649 650<p>I do accept external contributions, especially if compiling on another 651platform, get in touch with the list to upload the package, wrappers for 652various languages have been provided, and can be found in the <a 653href="python.html">bindings section</a></p> 654 655<p>Libxml2 is also available from CVS:</p> 656<ul> 657 <li><p>The <a 658 href="http://cvs.gnome.org/bonsai/rview.cgi?cvsroot=/cvs/gnome&dir=gnome-xml">Gnome 659 CVS base</a>. Check the <a 660 href="http://developer.gnome.org/tools/cvs.html">Gnome CVS Tools</a> 661 page; the CVS module is <b>libxml2</b>.</p> 662 </li> 663 <li>The <strong>libxslt</strong> module is also present there</li> 664</ul> 665 666<h2><a name="News">News</a></h2> 667 668<p>Items not finished and worked on, get in touch with the list if you want 669to help those</p> 670<ul> 671 <li>More testing on RelaxNG</li> 672 <li>Finishing up <a href="http://www.w3.org/TR/xmlschema-1/">XML 673 Schemas</a></li> 674</ul> 675 676<p>There is the list of public releases:</p> 677 678<h3>2.6.8: Mar 23 2004</h3> 679<ul> 680 <li>First step of the cleanup of the serialization code and APIs</li> 681 <li>XML Schemas: mixed content (Adam Dickmeiss), QName handling fixes (Adam 682 Dickmeiss), anyURI for "" (John Belmonte)</li> 683 <li>Python: Canonicalization C14N support added (Anthony Carrico)</li> 684 <li>xmlDocCopyNode() extension (William)</li> 685 <li>Relax-NG: fix when processing XInclude results (William), external 686 reference in interleave (William), missing error on <choice> 687 failure (William), memory leak in schemas datatype facets.</li> 688 <li>xmlWriter: patch for better DTD support (Alfred Mickautsch)</li> 689 <li>bug fixes: xmlXPathLangFunction memory leak (Mike Hommey and William 690 Brack), no ID errors if using HTML_PARSE_NOERROR, xmlcatalog fallbacks to 691 URI on SYSTEM lookup failure, XInclude parse flags inheritance (William), 692 XInclude and XPointer fixes for entities (William), XML parser bug 693 reported by Holger Rauch, nanohttp fd leak (William), regexps char 694 groups '-' handling (William), dictionnary reference counting problems, 695 do not close stderr.</li> 696 <li>performance patches from Petr Pajas</li> 697 <li>Documentation fixes: XML_CATALOG_FILES in man pages (Mike Hommey)</li> 698 <li>compilation and portability fixes: --without-valid, catalog cleanups 699 (Peter Breitenlohner), MingW patch (Roland Schwingel), cross-compilation 700 to Windows (Christophe de Vienne), --with-html-dir fixup (Julio Merino 701 Vidal), Windows build (Eric Zurcher)</li> 702</ul> 703 704<h3>2.6.7: Feb 23 2004</h3> 705<ul> 706 <li>documentation: tutorial updates (John Fleck), benchmark results</li> 707 <li>xmlWriter: updates and fixes (Alfred Mickautsch, Lucas Brasilino)</li> 708 <li>XPath optimization (Petr Pajas)</li> 709 <li>DTD ID handling optimization</li> 710 <li>bugfixes: xpath number with > 19 fractional (William Brack), push 711 mode with unescaped '>' characters, fix xmllint --stream --timing, fix 712 xmllint --memory --stream memory usage, xmlAttrSerializeTxtContent 713 handling NULL, trying to fix Relax-NG/Perl interface.</li> 714 <li>python: 2.3 compatibility, whitespace fixes (Malcolm Tredinnick)</li> 715 <li>Added relaxng option to xmllint --shell</li> 716</ul> 717 718<h3>2.6.6: Feb 12 2004</h3> 719<ul> 720 <li>nanohttp and nanoftp: buffer overflow error on URI parsing (Igor and 721 William) reported by Yuuichi Teranishi</li> 722 <li>bugfixes: make test and path issues, xmlWriter attribute serialization 723 (William Brack), xmlWriter indentation (William), schemas validation 724 (Eric Haszlakiewicz), XInclude dictionnaries issues (William and Oleg 725 Paraschenko), XInclude empty fallback (William), HTML warnings (William), 726 XPointer in XInclude (William), Python namespace serialization, 727 isolat1ToUTF8 bound error (Alfred Mickautsch), output of parameter 728 entities in internal subset (William), internal subset bug in push mode, 729 <xs:all> fix (Alexey Sarytchev)</li> 730 <li>Build: fix for automake-1.8 (Alexander Winston), warnings removal 731 (Philip Ludlam), SOCKLEN_T detection fixes (Daniel Richard), fix 732 --with-minimum configuration.</li> 733 <li>XInclude: allow the 2001 namespace without warning.</li> 734 <li>Documentation: missing example/index.html (John Fleck), version 735 dependancies (John Fleck)</li> 736 <li>reader API: structured error reporting (Steve Ball)</li> 737 <li>Windows compilation: mingw, msys (Mikhail Grushinskiy), function 738 prototype (Cameron Johnson), MSVC6 compiler warnings, _WINSOCKAPI_ 739 patch</li> 740 <li>Parsers: added xmlByteConsumed(ctxt) API to get the byte offest in 741 input.</li> 742</ul> 743 744<h3>2.6.5: Jan 25 2004</h3> 745<ul> 746 <li>Bugfixes: dictionnaries for schemas (William Brack), regexp segfault 747 (William), xs:all problem (William), a number of XPointer bugfixes 748 (William), xmllint error go to stderr, DTD validation problem with 749 namespace, memory leak (William), SAX1 cleanup and minimal options fixes 750 (Mark Vadoc), parser context reset on error (Shaun McCance), XPath union 751 evaluation problem (William) , xmlReallocLoc with NULL (Aleksey Sanin), 752 XML Schemas double free (Steve Ball), XInclude with no href, argument 753 callbacks order for XPath callbacks (Frederic Peters)</li> 754 <li>Documentation: python scripts (William Brack), xslt stylesheets (John 755 Fleck), doc (Sven Zimmerman), I/O example.</li> 756 <li>Python bindings: fixes (William), enum support (St�phane Bidoul), 757 structured error reporting (St�phane Bidoul)</li> 758 <li>XInclude: various fixes for conformance, problem related to dictionnary 759 references (William & me), recursion (William)</li> 760 <li>xmlWriter: indentation (Lucas Brasilino), memory leaks (Alfred 761 Mickautsch),</li> 762 <li>xmlSchemas: normalizedString datatype (John Belmonte)</li> 763 <li>code cleanup for strings functions (William)</li> 764 <li>Windows: compiler patches (Mark Vakoc)</li> 765 <li>Parser optimizations, a few new XPath and dictionnary APIs for future 766 XSLT optimizations.</li> 767</ul> 768 769<h3>2.6.4: Dec 24 2003</h3> 770<ul> 771 <li>Windows build fixes (Igor Zlatkovic)</li> 772 <li>Some serious XInclude problems reported by Oleg Paraschenko and</li> 773 <li>Unix and Makefile packaging fixes (me, William Brack,</li> 774 <li>Documentation improvements (John Fleck, William Brack), example fix 775 (Lucas Brasilino)</li> 776 <li>bugfixes: xmlTextReaderExpand() with xmlReaderWalker, XPath handling of 777 NULL strings (William Brack) , API building reader or parser from 778 filedescriptor should not close it, changed XPath sorting to be stable 779 again (William Brack), xmlGetNodePath() generating '(null)' (William 780 Brack), DTD validation and namespace bug (William Brack), XML Schemas 781 double inclusion behaviour</li> 782</ul> 783 784<h3>2.6.3: Dec 10 2003</h3> 785<ul> 786 <li>documentation updates and cleanup (DV, William Brack, John Fleck)</li> 787 <li>added a repository of examples, examples from Aleksey Sanin, Dodji 788 Seketeli, Alfred Mickautsch</li> 789 <li>Windows updates: Mark Vakoc, Igor Zlatkovic, Eric Zurcher, Mingw 790 (Kenneth Haley)</li> 791 <li>Unicode range checking (William Brack)</li> 792 <li>code cleanup (William Brack)</li> 793 <li>Python bindings: doc (John Fleck), bug fixes</li> 794 <li>UTF-16 cleanup and BOM issues (William Brack)</li> 795 <li>bug fixes: ID and xmlReader validation, XPath (William Brack), 796 xmlWriter (Alfred Mickautsch), hash.h inclusion problem, HTML parser 797 (James Bursa), attribute defaulting and validation, some serialization 798 cleanups, XML_GET_LINE macro, memory debug when using threads (William 799 Brack), serialization of attributes and entities content, xmlWriter 800 (Daniel Schulman)</li> 801 <li>XInclude bugfix, new APIs and update to the last version including the 802 namespace change.</li> 803 <li>XML Schemas improvements: include (Robert Stepanek), import and 804 namespace handling, fixed the regression tests troubles, added examples 805 based on Eric van der Vlist book, regexp fixes</li> 806 <li>preliminary pattern support for streaming (needed for schemas 807 constraints), added xmlTextReaderPreservePattern() to collect subdocument 808 when streaming.</li> 809 <li>various fixes in the structured error handling</li> 810</ul> 811 812<h3>2.6.2: Nov 4 2003</h3> 813<ul> 814 <li>XPath context unregistration fixes</li> 815 <li>text node coalescing fixes (Mark Lilback)</li> 816 <li>API to screate a W3C Schemas from an existing document (Steve Ball)</li> 817 <li>BeOS patches (Marcin 'Shard' Konicki)</li> 818 <li>xmlStrVPrintf function added (Aleksey Sanin)</li> 819 <li>compilation fixes (Mark Vakoc)</li> 820 <li>stdin parsing fix (William Brack)</li> 821 <li>a posteriori DTD validation fixes</li> 822 <li>xmlReader bug fixes: Walker fixes, python bindings</li> 823 <li>fixed xmlStopParser() to really stop the parser and errors</li> 824 <li>always generate line numbers when using the new xmlReadxxx 825 functions</li> 826 <li>added XInclude support to the xmlReader interface</li> 827 <li>implemented XML_PARSE_NONET parser option</li> 828 <li>DocBook XSLT processing bug fixed</li> 829 <li>HTML serialization for <p> elements (William Brack and me)</li> 830 <li>XPointer failure in XInclude are now handled as resource errors</li> 831 <li>fixed xmllint --html to use the HTML serializer on output (added 832 --xmlout to implement the previous behaviour of saving it using the XML 833 serializer)</li> 834</ul> 835 836<h3>2.6.1: Oct 28 2003</h3> 837<ul> 838 <li>Mostly bugfixes after the big 2.6.0 changes</li> 839 <li>Unix compilation patches: libxml.m4 (Patrick Welche), warnings cleanup 840 (William Brack)</li> 841 <li>Windows compilation patches (Joachim Bauch, Stephane Bidoul, Igor 842 Zlatkovic)</li> 843 <li>xmlWriter bugfix (Alfred Mickautsch)</li> 844 <li>chvalid.[ch]: couple of fixes from Stephane Bidoul</li> 845 <li>context reset: error state reset, push parser reset (Graham 846 Bennett)</li> 847 <li>context reuse: generate errors if file is not readable</li> 848 <li>defaulted attributes for element coming from internal entities 849 (Stephane Bidoul)</li> 850 <li>Python: tab and spaces mix (William Brack)</li> 851 <li>Error handler could crash in DTD validation in 2.6.0</li> 852 <li>xmlReader: do not use the document or element _private field</li> 853 <li>testSAX.c: avoid a problem with some PIs (Massimo Morara)</li> 854 <li>general bug fixes: mandatory encoding in text decl, serializing 855 Document Fragment nodes, xmlSearchNs 2.6.0 problem (Kasimier Buchcik), 856 XPath errors not reported, slow HTML parsing of large documents.</li> 857</ul> 858 859<h3>2.6.0: Oct 20 2003</h3> 860<ul> 861 <li>Major revision release: should be API and ABI compatible but got a lot 862 of change</li> 863 <li>Increased the library modularity, far more options can be stripped out, 864 a --with-minimum configuration will weight around 160KBytes</li> 865 <li>Use per parser and per document dictionnary, allocate names and small 866 text nodes from the dictionnary</li> 867 <li>Switch to a SAX2 like parser rewrote most of the XML parser core, 868 provides namespace resolution and defaulted attributes, minimize memory 869 allocations and copies, namespace checking and specific error handling, 870 immutable buffers, make predefined entities static structures, etc...</li> 871 <li>rewrote all the error handling in the library, all errors can be 872 intercepted at a structured level, with precise information 873 available.</li> 874 <li>New simpler and more generic XML and HTML parser APIs, allowing to 875 easilly modify the parsing options and reuse parser context for multiple 876 consecutive documents.</li> 877 <li>Similar new APIs for the xmlReader, for options and reuse, provided new 878 functions to access content as const strings, use them for Python 879 bindings</li> 880 <li>a lot of other smaller API improvements: xmlStrPrintf (Aleksey Sanin), 881 Walker i.e. reader on a document tree based on Alfred Mickautsch code, 882 make room in nodes for line numbers, reference counting and future PSVI 883 extensions, generation of character ranges to be checked with faster 884 algorithm (William), xmlParserMaxDepth (Crutcher Dunnavant), buffer 885 access</li> 886 <li>New xmlWriter API provided by Alfred Mickautsch</li> 887 <li>Schemas: base64 support by Anthony Carrico</li> 888 <li>Parser<->HTTP integration fix, proper processing of the Mime-Type 889 and charset informations if available.</li> 890 <li>Relax-NG: bug fixes including the one reported by Martijn Faassen and 891 zeroOrMore, better error reporting.</li> 892 <li>Python bindings (St�phane Bidoul), never use stdout for errors 893 output</li> 894 <li>Portability: all the headers have macros for export and calling 895 convention definitions (Igor Zlatkovic), VMS update (Craig A. Berry), 896 Windows: threads (Jesse Pelton), Borland compiler (Eric Zurcher, Igor), 897 Mingw (Igor), typos (Mark Vakoc), beta version (Stephane Bidoul), 898 warning cleanups on AIX and MIPS compilers (William Brack), BeOS (Marcin 899 'Shard' Konicki)</li> 900 <li>Documentation fixes and README (William Brack), search fix (William), 901 tutorial updates (John Fleck), namespace docs (Stefan Kost)</li> 902 <li>Bug fixes: xmlCleanupParser (Dave Beckett), threading uninitialized 903 mutexes, HTML doctype lowercase, SAX/IO (William), compression detection 904 and restore (William), attribute declaration in DTDs (William), namespace 905 on attribute in HTML output (William), input filename (Rob Richards), 906 namespace DTD validation, xmlReplaceNode (Chris Ryland), I/O callbacks 907 (Markus Keim), CDATA serialization (Shaun McCance), xmlReader (Peter 908 Derr), high codepoint charref like &#x10FFFF;, buffer access in push 909 mode (Justin Fletcher), TLS threads on Windows (Jesse Pelton), XPath bug 910 (William), xmlCleanupParser (Marc Liyanage), CDATA output (William), HTTP 911 error handling.</li> 912 <li>xmllint options: --dtdvalidfpi for Tobias Reif, --sax1 for compat 913 testing, --nodict for building without tree dictionnary, --nocdata to 914 replace CDATA by text, --nsclean to remove surperfluous namespace 915 declarations</li> 916 <li>added xml2-config --libtool-libs option from Kevin P. Fleming</li> 917 <li>a lot of profiling and tuning of the code, speedup patch for 918 xmlSearchNs() by Luca Padovani. The xmlReader should do far less 919 allocation and it speed should get closer to SAX. Chris Anderson worked 920 on speeding and cleaning up repetitive checking code.</li> 921 <li>cleanup of "make tests"</li> 922 <li>libxml-2.0-uninstalled.pc from Malcolm Tredinnick</li> 923 <li>deactivated the broken docBook SGML parser code and plugged the XML 924 parser instead.</li> 925</ul> 926 927<h3>2.5.11: Sep 9 2003</h3> 928 929<p>A bugfix only release:</p> 930<ul> 931 <li>risk of crash in Relax-NG</li> 932 <li>risk of crash when using multithreaded programs</li> 933</ul> 934 935<h3>2.5.10: Aug 15 2003</h3> 936 937<p>A bugfixes only release</p> 938<ul> 939 <li>Windows Makefiles (William Brack)</li> 940 <li>UTF-16 support fixes (Mark Itzcovitz)</li> 941 <li>Makefile and portability (William Brack) automake, Linux alpha, Mingw 942 on Windows (Mikhail Grushinskiy)</li> 943 <li>HTML parser (Oliver Stoeneberg)</li> 944 <li>XInclude performance problem reported by Kevin Ruscoe</li> 945 <li>XML parser performance problem reported by Grant Goodale</li> 946 <li>xmlSAXParseDTD() bug fix from Malcolm Tredinnick</li> 947 <li>and a couple other cleanup</li> 948</ul> 949 950<h3>2.5.9: Aug 9 2003</h3> 951<ul> 952 <li>bugfixes: IPv6 portability, xmlHasNsProp (Markus Keim), Windows build 953 (Wiliam Brake, Jesse Pelton, Igor), Schemas (Peter Sobisch), threading 954 (Rob Richards), hexBinary type (), UTF-16 BOM (Dodji Seketeli), 955 xmlReader, Relax-NG schemas compilation, namespace handling, EXSLT (Sean 956 Griffin), HTML parsing problem (William Brack), DTD validation for mixed 957 content + namespaces, HTML serialization, library initialization, 958 progressive HTML parser</li> 959 <li>better interfaces for Relax-NG error handling (Joachim Bauch, )</li> 960 <li>adding xmlXIncludeProcessTree() for XInclud'ing in a subtree</li> 961 <li>doc fixes and improvements (John Fleck)</li> 962 <li>configure flag for -with-fexceptions when embedding in C++</li> 963 <li>couple of new UTF-8 helper functions (William Brack)</li> 964 <li>general encoding cleanup + ISO-8859-x without iconv (Peter Jacobi)</li> 965 <li>xmlTextReader cleanup + enum for node types (Bjorn Reese)</li> 966 <li>general compilation/warning cleanup Solaris/HP-UX/... (William 967 Brack)</li> 968</ul> 969 970<h3>2.5.8: Jul 6 2003</h3> 971<ul> 972 <li>bugfixes: XPath, XInclude, file/URI mapping, UTF-16 save (Mark 973 Itzcovitz), UTF-8 checking, URI saving, error printing (William Brack), 974 PI related memleak, compilation without schemas or without xpath (Joerg 975 Schmitz-Linneweber/Garry Pennington), xmlUnlinkNode problem with DTDs, 976 rpm problem on , i86_64, removed a few compilation problems from 2.5.7, 977 xmlIOParseDTD, and xmlSAXParseDTD (Malcolm Tredinnick)</li> 978 <li>portability: DJGPP (MsDos) , OpenVMS (Craig A. Berry)</li> 979 <li>William Brack fixed multithreading lock problems</li> 980 <li>IPv6 patch for FTP and HTTP accesses (Archana Shah/Wipro)</li> 981 <li>Windows fixes (Igor Zlatkovic, Eric Zurcher), threading (St�phane 982 Bidoul)</li> 983 <li>A few W3C Schemas Structure improvements</li> 984 <li>W3C Schemas Datatype improvements (Charlie Bozeman)</li> 985 <li>Python bindings for thread globals (St�phane Bidoul), and method/class 986 generator</li> 987 <li>added --nonet option to xmllint</li> 988 <li>documentation improvements (John Fleck)</li> 989</ul> 990 991<h3>2.5.7: Apr 25 2003</h3> 992<ul> 993 <li>Relax-NG: Compiling to regexp and streaming validation on top of the 994 xmlReader interface, added to xmllint --stream</li> 995 <li>xmlReader: Expand(), Next() and DOM access glue, bug fixes</li> 996 <li>Support for large files: RGN validated a 4.5GB instance</li> 997 <li>Thread support is now configured in by default</li> 998 <li>Fixes: update of the Trio code (Bjorn), WXS Date and Duration fixes 999 (Charles Bozeman), DTD and namespaces (Brent Hendricks), HTML push parser 1000 and zero bytes handling, some missing Windows file path conversions, 1001 behaviour of the parser and validator in the presence of "out of memory" 1002 error conditions</li> 1003 <li>extended the API to be able to plug a garbage collecting memory 1004 allocator, added xmlMallocAtomic() and modified the allocations 1005 accordingly.</li> 1006 <li>Performances: removed excessive malloc() calls, speedup of the push and 1007 xmlReader interfaces, removed excessive thread locking</li> 1008 <li>Documentation: man page (John Fleck), xmlReader documentation</li> 1009 <li>Python: adding binding for xmlCatalogAddLocal (Brent M Hendricks)</li> 1010</ul> 1011 1012<h3>2.5.6: Apr 1 2003</h3> 1013<ul> 1014 <li>Fixed W3C XML Schemas datatype, should be compliant now except for 1015 binHex and base64 which are not supported yet.</li> 1016 <li>bug fixes: non-ASCII IDs, HTML output, XInclude on large docs and 1017 XInclude entities handling, encoding detection on external subsets, XML 1018 Schemas bugs and memory leaks, HTML parser (James Bursa)</li> 1019 <li>portability: python/trio (Albert Chin), Sun compiler warnings</li> 1020 <li>documentation: added --relaxng option to xmllint man page (John)</li> 1021 <li>improved error reporting: xml:space, start/end tag mismatches, Relax NG 1022 errors</li> 1023</ul> 1024 1025<h3>2.5.5: Mar 24 2003</h3> 1026<ul> 1027 <li>Lot of fixes on the Relax NG implementation. More testing including 1028 DocBook and TEI examples.</li> 1029 <li>Increased the support for W3C XML Schemas datatype</li> 1030 <li>Several bug fixes in the URI handling layer</li> 1031 <li>Bug fixes: HTML parser, xmlReader, DTD validation, XPath, encoding 1032 conversion, line counting in the parser.</li> 1033 <li>Added support for $XMLLINT_INDENT environment variable, FTP delete</li> 1034 <li>Fixed the RPM spec file name</li> 1035</ul> 1036 1037<h3>2.5.4: Feb 20 2003</h3> 1038<ul> 1039 <li>Conformance testing and lot of fixes on Relax NG and XInclude 1040 implementation</li> 1041 <li>Implementation of XPointer element() scheme</li> 1042 <li>Bug fixes: XML parser, XInclude entities merge, validity checking on 1043 namespaces, 1044 <p>2 serialization bugs, node info generation problems, a DTD regexp 1045 generation problem.</p> 1046 </li> 1047 <li>Portability: windows updates and path canonicalization (Igor)</li> 1048 <li>A few typo fixes (Kjartan Maraas)</li> 1049 <li>Python bindings generator fixes (Stephane Bidoul)</li> 1050</ul> 1051 1052<h3>2.5.3: Feb 10 2003</h3> 1053<ul> 1054 <li>RelaxNG and XML Schemas datatypes improvements, and added a first 1055 version of RelaxNG Python bindings</li> 1056 <li>Fixes: XLink (Sean Chittenden), XInclude (Sean Chittenden), API fix for 1057 serializing namespace nodes, encoding conversion bug, XHTML1 1058 serialization</li> 1059 <li>Portability fixes: Windows (Igor), AMD 64bits RPM spec file</li> 1060</ul> 1061 1062<h3>2.5.2: Feb 5 2003</h3> 1063<ul> 1064 <li>First implementation of RelaxNG, added --relaxng flag to xmllint</li> 1065 <li>Schemas support now compiled in by default.</li> 1066 <li>Bug fixes: DTD validation, namespace checking, XInclude and entities, 1067 delegateURI in XML Catalogs, HTML parser, XML reader (St�phane Bidoul), 1068 XPath parser and evaluation, UTF8ToUTF8 serialization, XML reader memory 1069 consumption, HTML parser, HTML serialization in the presence of 1070 namespaces</li> 1071 <li>added an HTML API to check elements and attributes.</li> 1072 <li>Documentation improvement, PDF for the tutorial (John Fleck), doc 1073 patches (Stefan Kost)</li> 1074 <li>Portability fixes: NetBSD (Julio Merino), Windows (Igor Zlatkovic)</li> 1075 <li>Added python bindings for XPointer, contextual error reporting 1076 (St�phane Bidoul)</li> 1077 <li>URI/file escaping problems (Stefano Zacchiroli)</li> 1078</ul> 1079 1080<h3>2.5.1: Jan 8 2003</h3> 1081<ul> 1082 <li>Fixes a memory leak and configuration/compilation problems in 2.5.0</li> 1083 <li>documentation updates (John)</li> 1084 <li>a couple of XmlTextReader fixes</li> 1085</ul> 1086 1087<h3>2.5.0: Jan 6 2003</h3> 1088<ul> 1089 <li>New <a href="xmlreader.html">XmltextReader interface</a> based on C# 1090 API (with help of St�phane Bidoul)</li> 1091 <li>Windows: more exports, including the new API (Igor)</li> 1092 <li>XInclude fallback fix</li> 1093 <li>Python: bindings for the new API, packaging (St�phane Bidoul), 1094 drv_libxml2.py Python xml.sax driver (St�phane Bidoul), fixes, speedup 1095 and iterators for Python-2.2 (Hannu Krosing)</li> 1096 <li>Tutorial fixes (john Fleck and Niraj Tolia) xmllint man update 1097 (John)</li> 1098 <li>Fix an XML parser bug raised by Vyacheslav Pindyura</li> 1099 <li>Fix for VMS serialization (Nigel Hall) and config (Craig A. Berry)</li> 1100 <li>Entities handling fixes</li> 1101 <li>new API to optionally track node creation and deletion (Lukas 1102 Schroeder)</li> 1103 <li>Added documentation for the XmltextReader interface and some <a 1104 href="guidelines.html">XML guidelines</a></li> 1105</ul> 1106 1107<h3>2.4.30: Dec 12 2002</h3> 1108<ul> 1109 <li>2.4.29 broke the python bindings, rereleasing</li> 1110 <li>Improvement/fixes of the XML API generator, and couple of minor code 1111 fixes.</li> 1112</ul> 1113 1114<h3>2.4.29: Dec 11 2002</h3> 1115<ul> 1116 <li>Windows fixes (Igor): Windows CE port, pthread linking, python bindings 1117 (St�phane Bidoul), Mingw (Magnus Henoch), and export list updates</li> 1118 <li>Fix for prev in python bindings (ERDI Gergo)</li> 1119 <li>Fix for entities handling (Marcus Clarke)</li> 1120 <li>Refactored the XML and HTML dumps to a single code path, fixed XHTML1 1121 dump</li> 1122 <li>Fix for URI parsing when handling URNs with fragment identifiers</li> 1123 <li>Fix for HTTP URL escaping problem</li> 1124 <li>added an TextXmlReader (C#) like API (work in progress)</li> 1125 <li>Rewrote the API in XML generation script, includes a C parser and saves 1126 more informations needed for C# bindings</li> 1127</ul> 1128 1129<h3>2.4.28: Nov 22 2002</h3> 1130<ul> 1131 <li>a couple of python binding fixes</li> 1132 <li>2 bug fixes in the XML push parser</li> 1133 <li>potential memory leak removed (Martin Stoilov)</li> 1134 <li>fix to the configure script for Unix (Dimitri Papadopoulos)</li> 1135 <li>added encoding support for XInclude parse="text"</li> 1136 <li>autodetection of XHTML1 and specific serialization rules added</li> 1137 <li>nasty threading bug fixed (William Brack)</li> 1138</ul> 1139 1140<h3>2.4.27: Nov 17 2002</h3> 1141<ul> 1142 <li>fixes for the Python bindings</li> 1143 <li>a number of bug fixes: SGML catalogs, xmlParseBalancedChunkMemory(), 1144 HTML parser, Schemas (Charles Bozeman), document fragment support 1145 (Christian Glahn), xmlReconciliateNs (Brian Stafford), XPointer, 1146 xmlFreeNode(), xmlSAXParseMemory (Peter Jones), xmlGetNodePath (Petr 1147 Pajas), entities processing</li> 1148 <li>added grep to xmllint --shell</li> 1149 <li>VMS update patch from Craig A. Berry</li> 1150 <li>cleanup of the Windows build with support for more compilers (Igor), 1151 better thread support on Windows</li> 1152 <li>cleanup of Unix Makefiles and spec file</li> 1153 <li>Improvements to the documentation (John Fleck)</li> 1154</ul> 1155 1156<h3>2.4.26: Oct 18 2002</h3> 1157<ul> 1158 <li>Patches for Windows CE port, improvements on Windows paths handling</li> 1159 <li>Fixes to the validation code (DTD and Schemas), xmlNodeGetPath() , 1160 HTML serialization, Namespace compliance, and a number of small 1161 problems</li> 1162</ul> 1163 1164<h3>2.4.25: Sep 26 2002</h3> 1165<ul> 1166 <li>A number of bug fixes: XPath, validation, Python bindings, DOM and 1167 tree, xmlI/O, Html</li> 1168 <li>Serious rewrite of XInclude</li> 1169 <li>Made XML Schemas regexp part of the default build and APIs, small fix 1170 and improvement of the regexp core</li> 1171 <li>Changed the validation code to reuse XML Schemas regexp APIs</li> 1172 <li>Better handling of Windows file paths, improvement of Makefiles (Igor, 1173 Daniel Gehriger, Mark Vakoc)</li> 1174 <li>Improved the python I/O bindings, the tests, added resolver and regexp 1175 APIs</li> 1176 <li>New logos from Marc Liyanage</li> 1177 <li>Tutorial improvements: John Fleck, Christopher Harris</li> 1178 <li>Makefile: Fixes for AMD x86_64 (Mandrake), DESTDIR (Christophe 1179 Merlet)</li> 1180 <li>removal of all stderr/perror use for error reporting</li> 1181 <li>Better error reporting: XPath and DTD validation</li> 1182 <li>update of the trio portability layer (Bjorn Reese)</li> 1183</ul> 1184 1185<p><strong>2.4.24: Aug 22 2002</strong></p> 1186<ul> 1187 <li>XPath fixes (William), xf:escape-uri() (Wesley Terpstra)</li> 1188 <li>Python binding fixes: makefiles (William), generator, rpm build, x86-64 1189 (fcrozat)</li> 1190 <li>HTML <style> and boolean attributes serializer fixes</li> 1191 <li>C14N improvements by Aleksey</li> 1192 <li>doc cleanups: Rick Jones</li> 1193 <li>Windows compiler makefile updates: Igor and Elizabeth Barham</li> 1194 <li>XInclude: implementation of fallback and xml:base fixup added</li> 1195</ul> 1196 1197<h3>2.4.23: July 6 2002</h3> 1198<ul> 1199 <li>performances patches: Peter Jacobi</li> 1200 <li>c14n fixes, testsuite and performances: Aleksey Sanin</li> 1201 <li>added xmlDocFormatDump: Chema Celorio</li> 1202 <li>new tutorial: John Fleck</li> 1203 <li>new hash functions and performances: Sander Vesik, portability fix from 1204 Peter Jacobi</li> 1205 <li>a number of bug fixes: XPath (William Brack, Richard Jinks), XML and 1206 HTML parsers, ID lookup function</li> 1207 <li>removal of all remaining sprintf: Aleksey Sanin</li> 1208</ul> 1209 1210<h3>2.4.22: May 27 2002</h3> 1211<ul> 1212 <li>a number of bug fixes: configure scripts, base handling, parser, memory 1213 usage, HTML parser, XPath, documentation (Christian Cornelssen), 1214 indentation, URI parsing</li> 1215 <li>Optimizations for XMLSec, fixing and making public some of the network 1216 protocol handlers (Aleksey)</li> 1217 <li>performance patch from Gary Pennington</li> 1218 <li>Charles Bozeman provided date and time support for XML Schemas 1219 datatypes</li> 1220</ul> 1221 1222<h3>2.4.21: Apr 29 2002</h3> 1223 1224<p>This release is both a bug fix release and also contains the early XML 1225Schemas <a href="http://www.w3.org/TR/xmlschema-1/">structures</a> and <a 1226href="http://www.w3.org/TR/xmlschema-2/">datatypes</a> code, beware, all 1227interfaces are likely to change, there is huge holes, it is clearly a work in 1228progress and don't even think of putting this code in a production system, 1229it's actually not compiled in by default. The real fixes are:</p> 1230<ul> 1231 <li>a couple of bugs or limitations introduced in 2.4.20</li> 1232 <li>patches for Borland C++ and MSC by Igor</li> 1233 <li>some fixes on XPath strings and conformance patches by Richard 1234 Jinks</li> 1235 <li>patch from Aleksey for the ExcC14N specification</li> 1236 <li>OSF/1 bug fix by Bjorn</li> 1237</ul> 1238 1239<h3>2.4.20: Apr 15 2002</h3> 1240<ul> 1241 <li>bug fixes: file descriptor leak, XPath, HTML output, DTD validation</li> 1242 <li>XPath conformance testing by Richard Jinks</li> 1243 <li>Portability fixes: Solaris, MPE/iX, Windows, OSF/1, python bindings, 1244 libxml.m4</li> 1245</ul> 1246 1247<h3>2.4.19: Mar 25 2002</h3> 1248<ul> 1249 <li>bug fixes: half a dozen XPath bugs, Validation, ISO-Latin to UTF8 1250 encoder</li> 1251 <li>portability fixes in the HTTP code</li> 1252 <li>memory allocation checks using valgrind, and profiling tests</li> 1253 <li>revamp of the Windows build and Makefiles</li> 1254</ul> 1255 1256<h3>2.4.18: Mar 18 2002</h3> 1257<ul> 1258 <li>bug fixes: tree, SAX, canonicalization, validation, portability, 1259 XPath</li> 1260 <li>removed the --with-buffer option it was becoming unmaintainable</li> 1261 <li>serious cleanup of the Python makefiles</li> 1262 <li>speedup patch to XPath very effective for DocBook stylesheets</li> 1263 <li>Fixes for Windows build, cleanup of the documentation</li> 1264</ul> 1265 1266<h3>2.4.17: Mar 8 2002</h3> 1267<ul> 1268 <li>a lot of bug fixes, including "namespace nodes have no parents in 1269 XPath"</li> 1270 <li>fixed/improved the Python wrappers, added more examples and more 1271 regression tests, XPath extension functions can now return node-sets</li> 1272 <li>added the XML Canonicalization support from Aleksey Sanin</li> 1273</ul> 1274 1275<h3>2.4.16: Feb 20 2002</h3> 1276<ul> 1277 <li>a lot of bug fixes, most of them were triggered by the XML Testsuite 1278 from OASIS and W3C. Compliance has been significantly improved.</li> 1279 <li>a couple of portability fixes too.</li> 1280</ul> 1281 1282<h3>2.4.15: Feb 11 2002</h3> 1283<ul> 1284 <li>Fixed the Makefiles, especially the python module ones</li> 1285 <li>A few bug fixes and cleanup</li> 1286 <li>Includes cleanup</li> 1287</ul> 1288 1289<h3>2.4.14: Feb 8 2002</h3> 1290<ul> 1291 <li>Change of License to the <a 1292 href="http://www.opensource.org/licenses/mit-license.html">MIT 1293 License</a> basically for integration in XFree86 codebase, and removing 1294 confusion around the previous dual-licensing</li> 1295 <li>added Python bindings, beta software but should already be quite 1296 complete</li> 1297 <li>a large number of fixes and cleanups, especially for all tree 1298 manipulations</li> 1299 <li>cleanup of the headers, generation of a reference API definition in 1300 XML</li> 1301</ul> 1302 1303<h3>2.4.13: Jan 14 2002</h3> 1304<ul> 1305 <li>update of the documentation: John Fleck and Charlie Bozeman</li> 1306 <li>cleanup of timing code from Justin Fletcher</li> 1307 <li>fixes for Windows and initial thread support on Win32: Igor and Serguei 1308 Narojnyi</li> 1309 <li>Cygwin patch from Robert Collins</li> 1310 <li>added xmlSetEntityReferenceFunc() for Keith Isdale work on xsldbg</li> 1311</ul> 1312 1313<h3>2.4.12: Dec 7 2001</h3> 1314<ul> 1315 <li>a few bug fixes: thread (Gary Pennington), xmllint (Geert Kloosterman), 1316 XML parser (Robin Berjon), XPointer (Danny Jamshy), I/O cleanups 1317 (robert)</li> 1318 <li>Eric Lavigne contributed project files for MacOS</li> 1319 <li>some makefiles cleanups</li> 1320</ul> 1321 1322<h3>2.4.11: Nov 26 2001</h3> 1323<ul> 1324 <li>fixed a couple of errors in the includes, fixed a few bugs, some code 1325 cleanups</li> 1326 <li>xmllint man pages improvement by Heiko Rupp</li> 1327 <li>updated VMS build instructions from John A Fotheringham</li> 1328 <li>Windows Makefiles updates from Igor</li> 1329</ul> 1330 1331<h3>2.4.10: Nov 10 2001</h3> 1332<ul> 1333 <li>URI escaping fix (Joel Young)</li> 1334 <li>added xmlGetNodePath() (for paths or XPointers generation)</li> 1335 <li>Fixes namespace handling problems when using DTD and validation</li> 1336 <li>improvements on xmllint: Morus Walter patches for --format and 1337 --encode, Stefan Kost and Heiko Rupp improvements on the --shell</li> 1338 <li>fixes for xmlcatalog linking pointed by Weiqi Gao</li> 1339 <li>fixes to the HTML parser</li> 1340</ul> 1341 1342<h3>2.4.9: Nov 6 2001</h3> 1343<ul> 1344 <li>fixes more catalog bugs</li> 1345 <li>avoid a compilation problem, improve xmlGetLineNo()</li> 1346</ul> 1347 1348<h3>2.4.8: Nov 4 2001</h3> 1349<ul> 1350 <li>fixed SGML catalogs broken in previous release, updated xmlcatalog 1351 tool</li> 1352 <li>fixed a compile errors and some includes troubles.</li> 1353</ul> 1354 1355<h3>2.4.7: Oct 30 2001</h3> 1356<ul> 1357 <li>exported some debugging interfaces</li> 1358 <li>serious rewrite of the catalog code</li> 1359 <li>integrated Gary Pennington thread safety patch, added configure option 1360 and regression tests</li> 1361 <li>removed an HTML parser bug</li> 1362 <li>fixed a couple of potentially serious validation bugs</li> 1363 <li>integrated the SGML DocBook support in xmllint</li> 1364 <li>changed the nanoftp anonymous login passwd</li> 1365 <li>some I/O cleanup and a couple of interfaces for Perl wrapper</li> 1366 <li>general bug fixes</li> 1367 <li>updated xmllint man page by John Fleck</li> 1368 <li>some VMS and Windows updates</li> 1369</ul> 1370 1371<h3>2.4.6: Oct 10 2001</h3> 1372<ul> 1373 <li>added an updated man pages by John Fleck</li> 1374 <li>portability and configure fixes</li> 1375 <li>an infinite loop on the HTML parser was removed (William)</li> 1376 <li>Windows makefile patches from Igor</li> 1377 <li>fixed half a dozen bugs reported for libxml or libxslt</li> 1378 <li>updated xmlcatalog to be able to modify SGML super catalogs</li> 1379</ul> 1380 1381<h3>2.4.5: Sep 14 2001</h3> 1382<ul> 1383 <li>Remove a few annoying bugs in 2.4.4</li> 1384 <li>forces the HTML serializer to output decimal charrefs since some 1385 version of Netscape can't handle hexadecimal ones</li> 1386</ul> 1387 1388<h3>1.8.16: Sep 14 2001</h3> 1389<ul> 1390 <li>maintenance release of the old libxml1 branch, couple of bug and 1391 portability fixes</li> 1392</ul> 1393 1394<h3>2.4.4: Sep 12 2001</h3> 1395<ul> 1396 <li>added --convert to xmlcatalog, bug fixes and cleanups of XML 1397 Catalog</li> 1398 <li>a few bug fixes and some portability changes</li> 1399 <li>some documentation cleanups</li> 1400</ul> 1401 1402<h3>2.4.3: Aug 23 2001</h3> 1403<ul> 1404 <li>XML Catalog support see the doc</li> 1405 <li>New NaN/Infinity floating point code</li> 1406 <li>A few bug fixes</li> 1407</ul> 1408 1409<h3>2.4.2: Aug 15 2001</h3> 1410<ul> 1411 <li>adds xmlLineNumbersDefault() to control line number generation</li> 1412 <li>lot of bug fixes</li> 1413 <li>the Microsoft MSC projects files should now be up to date</li> 1414 <li>inheritance of namespaces from DTD defaulted attributes</li> 1415 <li>fixes a serious potential security bug</li> 1416 <li>added a --format option to xmllint</li> 1417</ul> 1418 1419<h3>2.4.1: July 24 2001</h3> 1420<ul> 1421 <li>possibility to keep line numbers in the tree</li> 1422 <li>some computation NaN fixes</li> 1423 <li>extension of the XPath API</li> 1424 <li>cleanup for alpha and ia64 targets</li> 1425 <li>patch to allow saving through HTTP PUT or POST</li> 1426</ul> 1427 1428<h3>2.4.0: July 10 2001</h3> 1429<ul> 1430 <li>Fixed a few bugs in XPath, validation, and tree handling.</li> 1431 <li>Fixed XML Base implementation, added a couple of examples to the 1432 regression tests</li> 1433 <li>A bit of cleanup</li> 1434</ul> 1435 1436<h3>2.3.14: July 5 2001</h3> 1437<ul> 1438 <li>fixed some entities problems and reduce memory requirement when 1439 substituting them</li> 1440 <li>lots of improvements in the XPath queries interpreter can be 1441 substantially faster</li> 1442 <li>Makefiles and configure cleanups</li> 1443 <li>Fixes to XPath variable eval, and compare on empty node set</li> 1444 <li>HTML tag closing bug fixed</li> 1445 <li>Fixed an URI reference computation problem when validating</li> 1446</ul> 1447 1448<h3>2.3.13: June 28 2001</h3> 1449<ul> 1450 <li>2.3.12 configure.in was broken as well as the push mode XML parser</li> 1451 <li>a few more fixes for compilation on Windows MSC by Yon Derek</li> 1452</ul> 1453 1454<h3>1.8.14: June 28 2001</h3> 1455<ul> 1456 <li>Zbigniew Chyla gave a patch to use the old XML parser in push mode</li> 1457 <li>Small Makefile fix</li> 1458</ul> 1459 1460<h3>2.3.12: June 26 2001</h3> 1461<ul> 1462 <li>lots of cleanup</li> 1463 <li>a couple of validation fix</li> 1464 <li>fixed line number counting</li> 1465 <li>fixed serious problems in the XInclude processing</li> 1466 <li>added support for UTF8 BOM at beginning of entities</li> 1467 <li>fixed a strange gcc optimizer bugs in xpath handling of float, gcc-3.0 1468 miscompile uri.c (William), Thomas Leitner provided a fix for the 1469 optimizer on Tru64</li> 1470 <li>incorporated Yon Derek and Igor Zlatkovic fixes and improvements for 1471 compilation on Windows MSC</li> 1472 <li>update of libxml-doc.el (Felix Natter)</li> 1473 <li>fixed 2 bugs in URI normalization code</li> 1474</ul> 1475 1476<h3>2.3.11: June 17 2001</h3> 1477<ul> 1478 <li>updates to trio, Makefiles and configure should fix some portability 1479 problems (alpha)</li> 1480 <li>fixed some HTML serialization problems (pre, script, and block/inline 1481 handling), added encoding aware APIs, cleanup of this code</li> 1482 <li>added xmlHasNsProp()</li> 1483 <li>implemented a specific PI for encoding support in the DocBook SGML 1484 parser</li> 1485 <li>some XPath fixes (-Infinity, / as a function parameter and namespaces 1486 node selection)</li> 1487 <li>fixed a performance problem and an error in the validation code</li> 1488 <li>fixed XInclude routine to implement the recursive behaviour</li> 1489 <li>fixed xmlFreeNode problem when libxml is included statically twice</li> 1490 <li>added --version to xmllint for bug reports</li> 1491</ul> 1492 1493<h3>2.3.10: June 1 2001</h3> 1494<ul> 1495 <li>fixed the SGML catalog support</li> 1496 <li>a number of reported bugs got fixed, in XPath, iconv detection, 1497 XInclude processing</li> 1498 <li>XPath string function should now handle unicode correctly</li> 1499</ul> 1500 1501<h3>2.3.9: May 19 2001</h3> 1502 1503<p>Lots of bugfixes, and added a basic SGML catalog support:</p> 1504<ul> 1505 <li>HTML push bugfix #54891 and another patch from Jonas Borgstr�m</li> 1506 <li>some serious speed optimization again</li> 1507 <li>some documentation cleanups</li> 1508 <li>trying to get better linking on Solaris (-R)</li> 1509 <li>XPath API cleanup from Thomas Broyer</li> 1510 <li>Validation bug fixed #54631, added a patch from Gary Pennington, fixed 1511 xmlValidGetValidElements()</li> 1512 <li>Added an INSTALL file</li> 1513 <li>Attribute removal added to API: #54433</li> 1514 <li>added a basic support for SGML catalogs</li> 1515 <li>fixed xmlKeepBlanksDefault(0) API</li> 1516 <li>bugfix in xmlNodeGetLang()</li> 1517 <li>fixed a small configure portability problem</li> 1518 <li>fixed an inversion of SYSTEM and PUBLIC identifier in HTML document</li> 1519</ul> 1520 1521<h3>1.8.13: May 14 2001</h3> 1522<ul> 1523 <li>bugfixes release of the old libxml1 branch used by Gnome</li> 1524</ul> 1525 1526<h3>2.3.8: May 3 2001</h3> 1527<ul> 1528 <li>Integrated an SGML DocBook parser for the Gnome project</li> 1529 <li>Fixed a few things in the HTML parser</li> 1530 <li>Fixed some XPath bugs raised by XSLT use, tried to fix the floating 1531 point portability issue</li> 1532 <li>Speed improvement (8M/s for SAX, 3M/s for DOM, 1.5M/s for 1533 DOM+validation using the XML REC as input and a 700MHz celeron).</li> 1534 <li>incorporated more Windows cleanup</li> 1535 <li>added xmlSaveFormatFile()</li> 1536 <li>fixed problems in copying nodes with entities references (gdome)</li> 1537 <li>removed some troubles surrounding the new validation module</li> 1538</ul> 1539 1540<h3>2.3.7: April 22 2001</h3> 1541<ul> 1542 <li>lots of small bug fixes, corrected XPointer</li> 1543 <li>Non deterministic content model validation support</li> 1544 <li>added xmlDocCopyNode for gdome2</li> 1545 <li>revamped the way the HTML parser handles end of tags</li> 1546 <li>XPath: corrections of namespaces support and number formatting</li> 1547 <li>Windows: Igor Zlatkovic patches for MSC compilation</li> 1548 <li>HTML output fixes from P C Chow and William M. Brack</li> 1549 <li>Improved validation speed sensible for DocBook</li> 1550 <li>fixed a big bug with ID declared in external parsed entities</li> 1551 <li>portability fixes, update of Trio from Bjorn Reese</li> 1552</ul> 1553 1554<h3>2.3.6: April 8 2001</h3> 1555<ul> 1556 <li>Code cleanup using extreme gcc compiler warning options, found and 1557 cleared half a dozen potential problem</li> 1558 <li>the Eazel team found an XML parser bug</li> 1559 <li>cleaned up the user of some of the string formatting function. used the 1560 trio library code to provide the one needed when the platform is missing 1561 them</li> 1562 <li>xpath: removed a memory leak and fixed the predicate evaluation 1563 problem, extended the testsuite and cleaned up the result. XPointer seems 1564 broken ...</li> 1565</ul> 1566 1567<h3>2.3.5: Mar 23 2001</h3> 1568<ul> 1569 <li>Biggest change is separate parsing and evaluation of XPath expressions, 1570 there is some new APIs for this too</li> 1571 <li>included a number of bug fixes(XML push parser, 51876, notations, 1572 52299)</li> 1573 <li>Fixed some portability issues</li> 1574</ul> 1575 1576<h3>2.3.4: Mar 10 2001</h3> 1577<ul> 1578 <li>Fixed bugs #51860 and #51861</li> 1579 <li>Added a global variable xmlDefaultBufferSize to allow default buffer 1580 size to be application tunable.</li> 1581 <li>Some cleanup in the validation code, still a bug left and this part 1582 should probably be rewritten to support ambiguous content model :-\</li> 1583 <li>Fix a couple of serious bugs introduced or raised by changes in 2.3.3 1584 parser</li> 1585 <li>Fixed another bug in xmlNodeGetContent()</li> 1586 <li>Bjorn fixed XPath node collection and Number formatting</li> 1587 <li>Fixed a loop reported in the HTML parsing</li> 1588 <li>blank space are reported even if the Dtd content model proves that they 1589 are formatting spaces, this is for XML conformance</li> 1590</ul> 1591 1592<h3>2.3.3: Mar 1 2001</h3> 1593<ul> 1594 <li>small change in XPath for XSLT</li> 1595 <li>documentation cleanups</li> 1596 <li>fix in validation by Gary Pennington</li> 1597 <li>serious parsing performances improvements</li> 1598</ul> 1599 1600<h3>2.3.2: Feb 24 2001</h3> 1601<ul> 1602 <li>chasing XPath bugs, found a bunch, completed some TODO</li> 1603 <li>fixed a Dtd parsing bug</li> 1604 <li>fixed a bug in xmlNodeGetContent</li> 1605 <li>ID/IDREF support partly rewritten by Gary Pennington</li> 1606</ul> 1607 1608<h3>2.3.1: Feb 15 2001</h3> 1609<ul> 1610 <li>some XPath and HTML bug fixes for XSLT</li> 1611 <li>small extension of the hash table interfaces for DOM gdome2 1612 implementation</li> 1613 <li>A few bug fixes</li> 1614</ul> 1615 1616<h3>2.3.0: Feb 8 2001 (2.2.12 was on 25 Jan but I didn't kept track)</h3> 1617<ul> 1618 <li>Lots of XPath bug fixes</li> 1619 <li>Add a mode with Dtd lookup but without validation error reporting for 1620 XSLT</li> 1621 <li>Add support for text node without escaping (XSLT)</li> 1622 <li>bug fixes for xmlCheckFilename</li> 1623 <li>validation code bug fixes from Gary Pennington</li> 1624 <li>Patch from Paul D. Smith correcting URI path normalization</li> 1625 <li>Patch to allow simultaneous install of libxml-devel and 1626 libxml2-devel</li> 1627 <li>the example Makefile is now fixed</li> 1628 <li>added HTML to the RPM packages</li> 1629 <li>tree copying bugfixes</li> 1630 <li>updates to Windows makefiles</li> 1631 <li>optimization patch from Bjorn Reese</li> 1632</ul> 1633 1634<h3>2.2.11: Jan 4 2001</h3> 1635<ul> 1636 <li>bunch of bug fixes (memory I/O, xpath, ftp/http, ...)</li> 1637 <li>added htmlHandleOmittedElem()</li> 1638 <li>Applied Bjorn Reese's IPV6 first patch</li> 1639 <li>Applied Paul D. Smith patches for validation of XInclude results</li> 1640 <li>added XPointer xmlns() new scheme support</li> 1641</ul> 1642 1643<h3>2.2.10: Nov 25 2000</h3> 1644<ul> 1645 <li>Fix the Windows problems of 2.2.8</li> 1646 <li>integrate OpenVMS patches</li> 1647 <li>better handling of some nasty HTML input</li> 1648 <li>Improved the XPointer implementation</li> 1649 <li>integrate a number of provided patches</li> 1650</ul> 1651 1652<h3>2.2.9: Nov 25 2000</h3> 1653<ul> 1654 <li>erroneous release :-(</li> 1655</ul> 1656 1657<h3>2.2.8: Nov 13 2000</h3> 1658<ul> 1659 <li>First version of <a href="http://www.w3.org/TR/xinclude">XInclude</a> 1660 support</li> 1661 <li>Patch in conditional section handling</li> 1662 <li>updated MS compiler project</li> 1663 <li>fixed some XPath problems</li> 1664 <li>added an URI escaping function</li> 1665 <li>some other bug fixes</li> 1666</ul> 1667 1668<h3>2.2.7: Oct 31 2000</h3> 1669<ul> 1670 <li>added message redirection</li> 1671 <li>XPath improvements (thanks TOM !)</li> 1672 <li>xmlIOParseDTD() added</li> 1673 <li>various small fixes in the HTML, URI, HTTP and XPointer support</li> 1674 <li>some cleanup of the Makefile, autoconf and the distribution content</li> 1675</ul> 1676 1677<h3>2.2.6: Oct 25 2000:</h3> 1678<ul> 1679 <li>Added an hash table module, migrated a number of internal structure to 1680 those</li> 1681 <li>Fixed a posteriori validation problems</li> 1682 <li>HTTP module cleanups</li> 1683 <li>HTML parser improvements (tag errors, script/style handling, attribute 1684 normalization)</li> 1685 <li>coalescing of adjacent text nodes</li> 1686 <li>couple of XPath bug fixes, exported the internal API</li> 1687</ul> 1688 1689<h3>2.2.5: Oct 15 2000:</h3> 1690<ul> 1691 <li>XPointer implementation and testsuite</li> 1692 <li>Lot of XPath fixes, added variable and functions registration, more 1693 tests</li> 1694 <li>Portability fixes, lots of enhancements toward an easy Windows build 1695 and release</li> 1696 <li>Late validation fixes</li> 1697 <li>Integrated a lot of contributed patches</li> 1698 <li>added memory management docs</li> 1699 <li>a performance problem when using large buffer seems fixed</li> 1700</ul> 1701 1702<h3>2.2.4: Oct 1 2000:</h3> 1703<ul> 1704 <li>main XPath problem fixed</li> 1705 <li>Integrated portability patches for Windows</li> 1706 <li>Serious bug fixes on the URI and HTML code</li> 1707</ul> 1708 1709<h3>2.2.3: Sep 17 2000</h3> 1710<ul> 1711 <li>bug fixes</li> 1712 <li>cleanup of entity handling code</li> 1713 <li>overall review of all loops in the parsers, all sprintf usage has been 1714 checked too</li> 1715 <li>Far better handling of larges Dtd. Validating against DocBook XML Dtd 1716 works smoothly now.</li> 1717</ul> 1718 1719<h3>1.8.10: Sep 6 2000</h3> 1720<ul> 1721 <li>bug fix release for some Gnome projects</li> 1722</ul> 1723 1724<h3>2.2.2: August 12 2000</h3> 1725<ul> 1726 <li>mostly bug fixes</li> 1727 <li>started adding routines to access xml parser context options</li> 1728</ul> 1729 1730<h3>2.2.1: July 21 2000</h3> 1731<ul> 1732 <li>a purely bug fixes release</li> 1733 <li>fixed an encoding support problem when parsing from a memory block</li> 1734 <li>fixed a DOCTYPE parsing problem</li> 1735 <li>removed a bug in the function allowing to override the memory 1736 allocation routines</li> 1737</ul> 1738 1739<h3>2.2.0: July 14 2000</h3> 1740<ul> 1741 <li>applied a lot of portability fixes</li> 1742 <li>better encoding support/cleanup and saving (content is now always 1743 encoded in UTF-8)</li> 1744 <li>the HTML parser now correctly handles encodings</li> 1745 <li>added xmlHasProp()</li> 1746 <li>fixed a serious problem with &#38;</li> 1747 <li>propagated the fix to FTP client</li> 1748 <li>cleanup, bugfixes, etc ...</li> 1749 <li>Added a page about <a href="encoding.html">libxml Internationalization 1750 support</a></li> 1751</ul> 1752 1753<h3>1.8.9: July 9 2000</h3> 1754<ul> 1755 <li>fixed the spec the RPMs should be better</li> 1756 <li>fixed a serious bug in the FTP implementation, released 1.8.9 to solve 1757 rpmfind users problem</li> 1758</ul> 1759 1760<h3>2.1.1: July 1 2000</h3> 1761<ul> 1762 <li>fixes a couple of bugs in the 2.1.0 packaging</li> 1763 <li>improvements on the HTML parser</li> 1764</ul> 1765 1766<h3>2.1.0 and 1.8.8: June 29 2000</h3> 1767<ul> 1768 <li>1.8.8 is mostly a commodity package for upgrading to libxml2 according 1769 to <a href="upgrade.html">new instructions</a>. It fixes a nasty problem 1770 about &#38; charref parsing</li> 1771 <li>2.1.0 also ease the upgrade from libxml v1 to the recent version. it 1772 also contains numerous fixes and enhancements: 1773 <ul> 1774 <li>added xmlStopParser() to stop parsing</li> 1775 <li>improved a lot parsing speed when there is large CDATA blocs</li> 1776 <li>includes XPath patches provided by Picdar Technology</li> 1777 <li>tried to fix as much as possible DTD validation and namespace 1778 related problems</li> 1779 <li>output to a given encoding has been added/tested</li> 1780 <li>lot of various fixes</li> 1781 </ul> 1782 </li> 1783</ul> 1784 1785<h3>2.0.0: Apr 12 2000</h3> 1786<ul> 1787 <li>First public release of libxml2. If you are using libxml, it's a good 1788 idea to check the 1.x to 2.x upgrade instructions. NOTE: while initially 1789 scheduled for Apr 3 the release occurred only on Apr 12 due to massive 1790 workload.</li> 1791 <li>The include are now located under $prefix/include/libxml (instead of 1792 $prefix/include/gnome-xml), they also are referenced by 1793 <pre>#include <libxml/xxx.h></pre> 1794 <p>instead of</p> 1795 <pre>#include "xxx.h"</pre> 1796 </li> 1797 <li>a new URI module for parsing URIs and following strictly RFC 2396</li> 1798 <li>the memory allocation routines used by libxml can now be overloaded 1799 dynamically by using xmlMemSetup()</li> 1800 <li>The previously CVS only tool tester has been renamed 1801 <strong>xmllint</strong> and is now installed as part of the libxml2 1802 package</li> 1803 <li>The I/O interface has been revamped. There is now ways to plug in 1804 specific I/O modules, either at the URI scheme detection level using 1805 xmlRegisterInputCallbacks() or by passing I/O functions when creating a 1806 parser context using xmlCreateIOParserCtxt()</li> 1807 <li>there is a C preprocessor macro LIBXML_VERSION providing the version 1808 number of the libxml module in use</li> 1809 <li>a number of optional features of libxml can now be excluded at 1810 configure time (FTP/HTTP/HTML/XPath/Debug)</li> 1811</ul> 1812 1813<h3>2.0.0beta: Mar 14 2000</h3> 1814<ul> 1815 <li>This is a first Beta release of libxml version 2</li> 1816 <li>It's available only from<a href="ftp://xmlsoft.org/">xmlsoft.org 1817 FTP</a>, it's packaged as libxml2-2.0.0beta and available as tar and 1818 RPMs</li> 1819 <li>This version is now the head in the Gnome CVS base, the old one is 1820 available under the tag LIB_XML_1_X</li> 1821 <li>This includes a very large set of changes. From a programmatic point 1822 of view applications should not have to be modified too much, check the 1823 <a href="upgrade.html">upgrade page</a></li> 1824 <li>Some interfaces may changes (especially a bit about encoding).</li> 1825 <li>the updates includes: 1826 <ul> 1827 <li>fix I18N support. ISO-Latin-x/UTF-8/UTF-16 (nearly) seems correctly 1828 handled now</li> 1829 <li>Better handling of entities, especially well-formedness checking 1830 and proper PEref extensions in external subsets</li> 1831 <li>DTD conditional sections</li> 1832 <li>Validation now correctly handle entities content</li> 1833 <li><a href="http://rpmfind.net/tools/gdome/messages/0039.html">change 1834 structures to accommodate DOM</a></li> 1835 </ul> 1836 </li> 1837 <li>Serious progress were made toward compliance, <a 1838 href="conf/result.html">here are the result of the test</a> against the 1839 OASIS testsuite (except the Japanese tests since I don't support that 1840 encoding yet). This URL is rebuilt every couple of hours using the CVS 1841 head version.</li> 1842</ul> 1843 1844<h3>1.8.7: Mar 6 2000</h3> 1845<ul> 1846 <li>This is a bug fix release:</li> 1847 <li>It is possible to disable the ignorable blanks heuristic used by 1848 libxml-1.x, a new function xmlKeepBlanksDefault(0) will allow this. Note 1849 that for adherence to XML spec, this behaviour will be disabled by 1850 default in 2.x . The same function will allow to keep compatibility for 1851 old code.</li> 1852 <li>Blanks in <a> </a> constructs are not ignored anymore, 1853 avoiding heuristic is really the Right Way :-\</li> 1854 <li>The unchecked use of snprintf which was breaking libxml-1.8.6 1855 compilation on some platforms has been fixed</li> 1856 <li>nanoftp.c nanohttp.c: Fixed '#' and '?' stripping when processing 1857 URIs</li> 1858</ul> 1859 1860<h3>1.8.6: Jan 31 2000</h3> 1861<ul> 1862 <li>added a nanoFTP transport module, debugged until the new version of <a 1863 href="http://rpmfind.net/linux/rpm2html/rpmfind.html">rpmfind</a> can use 1864 it without troubles</li> 1865</ul> 1866 1867<h3>1.8.5: Jan 21 2000</h3> 1868<ul> 1869 <li>adding APIs to parse a well balanced chunk of XML (production <a 1870 href="http://www.w3.org/TR/REC-xml#NT-content">[43] content</a> of the 1871 XML spec)</li> 1872 <li>fixed a hideous bug in xmlGetProp pointed by Rune.Djurhuus@fast.no</li> 1873 <li>Jody Goldberg <jgoldberg@home.com> provided another patch trying 1874 to solve the zlib checks problems</li> 1875 <li>The current state in gnome CVS base is expected to ship as 1.8.5 with 1876 gnumeric soon</li> 1877</ul> 1878 1879<h3>1.8.4: Jan 13 2000</h3> 1880<ul> 1881 <li>bug fixes, reintroduced xmlNewGlobalNs(), fixed xmlNewNs()</li> 1882 <li>all exit() call should have been removed from libxml</li> 1883 <li>fixed a problem with INCLUDE_WINSOCK on WIN32 platform</li> 1884 <li>added newDocFragment()</li> 1885</ul> 1886 1887<h3>1.8.3: Jan 5 2000</h3> 1888<ul> 1889 <li>a Push interface for the XML and HTML parsers</li> 1890 <li>a shell-like interface to the document tree (try tester --shell :-)</li> 1891 <li>lots of bug fixes and improvement added over XMas holidays</li> 1892 <li>fixed the DTD parsing code to work with the xhtml DTD</li> 1893 <li>added xmlRemoveProp(), xmlRemoveID() and xmlRemoveRef()</li> 1894 <li>Fixed bugs in xmlNewNs()</li> 1895 <li>External entity loading code has been revamped, now it uses 1896 xmlLoadExternalEntity(), some fix on entities processing were added</li> 1897 <li>cleaned up WIN32 includes of socket stuff</li> 1898</ul> 1899 1900<h3>1.8.2: Dec 21 1999</h3> 1901<ul> 1902 <li>I got another problem with includes and C++, I hope this issue is fixed 1903 for good this time</li> 1904 <li>Added a few tree modification functions: xmlReplaceNode, 1905 xmlAddPrevSibling, xmlAddNextSibling, xmlNodeSetName and 1906 xmlDocSetRootElement</li> 1907 <li>Tried to improve the HTML output with help from <a 1908 href="mailto:clahey@umich.edu">Chris Lahey</a></li> 1909</ul> 1910 1911<h3>1.8.1: Dec 18 1999</h3> 1912<ul> 1913 <li>various patches to avoid troubles when using libxml with C++ compilers 1914 the "namespace" keyword and C escaping in include files</li> 1915 <li>a problem in one of the core macros IS_CHAR was corrected</li> 1916 <li>fixed a bug introduced in 1.8.0 breaking default namespace processing, 1917 and more specifically the Dia application</li> 1918 <li>fixed a posteriori validation (validation after parsing, or by using a 1919 Dtd not specified in the original document)</li> 1920 <li>fixed a bug in</li> 1921</ul> 1922 1923<h3>1.8.0: Dec 12 1999</h3> 1924<ul> 1925 <li>cleanup, especially memory wise</li> 1926 <li>the parser should be more reliable, especially the HTML one, it should 1927 not crash, whatever the input !</li> 1928 <li>Integrated various patches, especially a speedup improvement for large 1929 dataset from <a href="mailto:cnygard@bellatlantic.net">Carl Nygard</a>, 1930 configure with --with-buffers to enable them.</li> 1931 <li>attribute normalization, oops should have been added long ago !</li> 1932 <li>attributes defaulted from DTDs should be available, xmlSetProp() now 1933 does entities escaping by default.</li> 1934</ul> 1935 1936<h3>1.7.4: Oct 25 1999</h3> 1937<ul> 1938 <li>Lots of HTML improvement</li> 1939 <li>Fixed some errors when saving both XML and HTML</li> 1940 <li>More examples, the regression tests should now look clean</li> 1941 <li>Fixed a bug with contiguous charref</li> 1942</ul> 1943 1944<h3>1.7.3: Sep 29 1999</h3> 1945<ul> 1946 <li>portability problems fixed</li> 1947 <li>snprintf was used unconditionally, leading to link problems on system 1948 were it's not available, fixed</li> 1949</ul> 1950 1951<h3>1.7.1: Sep 24 1999</h3> 1952<ul> 1953 <li>The basic type for strings manipulated by libxml has been renamed in 1954 1.7.1 from <strong>CHAR</strong> to <strong>xmlChar</strong>. The reason 1955 is that CHAR was conflicting with a predefined type on Windows. However 1956 on non WIN32 environment, compatibility is provided by the way of a 1957 <strong>#define </strong>.</li> 1958 <li>Changed another error : the use of a structure field called errno, and 1959 leading to troubles on platforms where it's a macro</li> 1960</ul> 1961 1962<h3>1.7.0: Sep 23 1999</h3> 1963<ul> 1964 <li>Added the ability to fetch remote DTD or parsed entities, see the <a 1965 href="html/libxml-nanohttp.html">nanohttp</a> module.</li> 1966 <li>Added an errno to report errors by another mean than a simple printf 1967 like callback</li> 1968 <li>Finished ID/IDREF support and checking when validation</li> 1969 <li>Serious memory leaks fixed (there is now a <a 1970 href="html/libxml-xmlmemory.html">memory wrapper</a> module)</li> 1971 <li>Improvement of <a href="http://www.w3.org/TR/xpath">XPath</a> 1972 implementation</li> 1973 <li>Added an HTML parser front-end</li> 1974</ul> 1975 1976<h2><a name="XML">XML</a></h2> 1977 1978<p><a href="http://www.w3.org/TR/REC-xml">XML is a standard</a> for 1979markup-based structured documents. Here is <a name="example">an example XML 1980document</a>:</p> 1981<pre><?xml version="1.0"?> 1982<EXAMPLE prop1="gnome is great" prop2="&amp; linux too"> 1983 <head> 1984 <title>Welcome to Gnome</title> 1985 </head> 1986 <chapter> 1987 <title>The Linux adventure</title> 1988 <p>bla bla bla ...</p> 1989 <image href="linus.gif"/> 1990 <p>...</p> 1991 </chapter> 1992</EXAMPLE></pre> 1993 1994<p>The first line specifies that it is an XML document and gives useful 1995information about its encoding. Then the rest of the document is a text 1996format whose structure is specified by tags between brackets. <strong>Each 1997tag opened has to be closed</strong>. XML is pedantic about this. However, if 1998a tag is empty (no content), a single tag can serve as both the opening and 1999closing tag if it ends with <code>/></code> rather than with 2000<code>></code>. Note that, for example, the image tag has no content (just 2001an attribute) and is closed by ending the tag with <code>/></code>.</p> 2002 2003<p>XML can be applied successfully to a wide range of tasks, ranging from 2004long term structured document maintenance (where it follows the steps of 2005SGML) to simple data encoding mechanisms like configuration file formatting 2006(glade), spreadsheets (gnumeric), or even shorter lived documents such as 2007WebDAV where it is used to encode remote calls between a client and a 2008server.</p> 2009 2010<h2><a name="XSLT">XSLT</a></h2> 2011 2012<p>Check <a href="http://xmlsoft.org/XSLT">the separate libxslt page</a></p> 2013 2014<p><a href="http://www.w3.org/TR/xslt">XSL Transformations</a>, is a 2015language for transforming XML documents into other XML documents (or 2016HTML/textual output).</p> 2017 2018<p>A separate library called libxslt is available implementing XSLT-1.0 for 2019libxml2. This module "libxslt" too can be found in the Gnome CVS base.</p> 2020 2021<p>You can check the <a 2022href="http://cvs.gnome.org/lxr/source/libxslt/FEATURES">features</a> 2023supported and the progresses on the <a 2024href="http://cvs.gnome.org/lxr/source/libxslt/ChangeLog" 2025name="Changelog">Changelog</a>.</p> 2026 2027<h2><a name="Python">Python and bindings</a></h2> 2028 2029<p>There are a number of language bindings and wrappers available for 2030libxml2, the list below is not exhaustive. Please contact the <a 2031href="http://mail.gnome.org/mailman/listinfo/xml-bindings">xml-bindings@gnome.org</a> 2032(<a href="http://mail.gnome.org/archives/xml-bindings/">archives</a>) in 2033order to get updates to this list or to discuss the specific topic of libxml2 2034or libxslt wrappers or bindings:</p> 2035<ul> 2036 <li><a href="http://libxmlplusplus.sourceforge.net/">Libxml++</a> seems the 2037 most up-to-date C++ bindings for libxml2, check the <a 2038 href="http://libxmlplusplus.sourceforge.net/reference/html/hierarchy.html">documentation</a> 2039 and the <a 2040 href="http://cvs.sourceforge.net/cgi-bin/viewcvs.cgi/libxmlplusplus/libxml%2b%2b/examples/">examples</a>.</li> 2041 <li>There is another <a href="http://libgdome-cpp.berlios.de/">C++ wrapper 2042 based on the gdome2 bindings</a> maintained by Tobias Peters.</li> 2043 <li>and a third C++ wrapper by Peter Jones <pjones@pmade.org> 2044 <p>Website: <a 2045 href="http://pmade.org/pjones/software/xmlwrapp/">http://pmade.org/pjones/software/xmlwrapp/</a></p> 2046 </li> 2047 <li><a 2048 href="http://mail.gnome.org/archives/xml/2001-March/msg00014.html">Matt 2049 Sergeant</a> developed <a 2050 href="http://axkit.org/download/">XML::LibXSLT</a>, a Perl wrapper for 2051 libxml2/libxslt as part of the <a href="http://axkit.com/">AxKit XML 2052 application server</a>.</li> 2053 <li>If you're interested into scripting XML processing, have a look at <a 2054 href="http://xsh.sourceforge.net/">XSH</a> an XML editing shell based on 2055 Libxml2 Perl bindings.</li> 2056 <li><a href="mailto:dkuhlman@cutter.rexx.com">Dave Kuhlman</a> provides an 2057 earlier version of the libxml/libxslt <a 2058 href="http://www.rexx.com/~dkuhlman">wrappers for Python</a>.</li> 2059 <li>Gopal.V and Peter Minten develop <a 2060 href="http://savannah.gnu.org/projects/libxmlsharp">libxml#</a>, a set of 2061 C# libxml2 bindings.</li> 2062 <li>Petr Kozelka provides <a 2063 href="http://sourceforge.net/projects/libxml2-pas">Pascal units to glue 2064 libxml2</a> with Kylix, Delphi and other Pascal compilers.</li> 2065 <li>Uwe Fechner also provides <a 2066 href="http://sourceforge.net/projects/idom2-pas/">idom2</a>, a DOM2 2067 implementation for Kylix2/D5/D6 from Borland.</li> 2068 <li>Wai-Sun "Squidster" Chia provides <a 2069 href="http://www.rubycolor.org/arc/redist/">bindings for Ruby</a> and 2070 libxml2 bindings are also available in Ruby through the <a 2071 href="http://libgdome-ruby.berlios.de/">libgdome-ruby</a> module 2072 maintained by Tobias Peters.</li> 2073 <li>Steve Ball and contributors maintains <a 2074 href="http://tclxml.sourceforge.net/">libxml2 and libxslt bindings for 2075 Tcl</a>.</li> 2076 <li>There is support for libxml2 in the DOM module of PHP.</li> 2077 <li><a href="http://savannah.gnu.org/projects/classpathx/">LibxmlJ</a> is 2078 an effort to create a 100% JAXP-compatible Java wrapper for libxml2 and 2079 libxslt as part of GNU ClasspathX project.</li> 2080 <li>Patrick McPhee provides Rexx bindings fof libxml2 and libxslt, look for 2081 <a href="http://www.interlog.com/~ptjm/software.html">RexxXML</a>.</li> 2082</ul> 2083 2084<p>The distribution includes a set of Python bindings, which are guaranteed 2085to be maintained as part of the library in the future, though the Python 2086interface have not yet reached the completeness of the C API.</p> 2087 2088<p><a href="mailto:stephane.bidoul@softwareag.com">St�phane Bidoul</a> 2089maintains <a href="http://users.skynet.be/sbi/libxml-python/">a Windows port 2090of the Python bindings</a>.</p> 2091 2092<p>Note to people interested in building bindings, the API is formalized as 2093<a href="libxml2-api.xml">an XML API description file</a> which allows to 2094automate a large part of the Python bindings, this includes function 2095descriptions, enums, structures, typedefs, etc... The Python script used to 2096build the bindings is python/generator.py in the source distribution.</p> 2097 2098<p>To install the Python bindings there are 2 options:</p> 2099<ul> 2100 <li>If you use an RPM based distribution, simply install the <a 2101 href="http://rpmfind.net/linux/rpm2html/search.php?query=libxml2-python">libxml2-python 2102 RPM</a> (and if needed the <a 2103 href="http://rpmfind.net/linux/rpm2html/search.php?query=libxslt-python">libxslt-python 2104 RPM</a>).</li> 2105 <li>Otherwise use the <a href="ftp://xmlsoft.org/python/">libxml2-python 2106 module distribution</a> corresponding to your installed version of 2107 libxml2 and libxslt. Note that to install it you will need both libxml2 2108 and libxslt installed and run "python setup.py build install" in the 2109 module tree.</li> 2110</ul> 2111 2112<p>The distribution includes a set of examples and regression tests for the 2113python bindings in the <code>python/tests</code> directory. Here are some 2114excerpts from those tests:</p> 2115 2116<h3>tst.py:</h3> 2117 2118<p>This is a basic test of the file interface and DOM navigation:</p> 2119<pre>import libxml2, sys 2120 2121doc = libxml2.parseFile("tst.xml") 2122if doc.name != "tst.xml": 2123 print "doc.name failed" 2124 sys.exit(1) 2125root = doc.children 2126if root.name != "doc": 2127 print "root.name failed" 2128 sys.exit(1) 2129child = root.children 2130if child.name != "foo": 2131 print "child.name failed" 2132 sys.exit(1) 2133doc.freeDoc()</pre> 2134 2135<p>The Python module is called libxml2; parseFile is the equivalent of 2136xmlParseFile (most of the bindings are automatically generated, and the xml 2137prefix is removed and the casing convention are kept). All node seen at the 2138binding level share the same subset of accessors:</p> 2139<ul> 2140 <li><code>name</code> : returns the node name</li> 2141 <li><code>type</code> : returns a string indicating the node type</li> 2142 <li><code>content</code> : returns the content of the node, it is based on 2143 xmlNodeGetContent() and hence is recursive.</li> 2144 <li><code>parent</code> , <code>children</code>, <code>last</code>, 2145 <code>next</code>, <code>prev</code>, <code>doc</code>, 2146 <code>properties</code>: pointing to the associated element in the tree, 2147 those may return None in case no such link exists.</li> 2148</ul> 2149 2150<p>Also note the need to explicitly deallocate documents with freeDoc() . 2151Reference counting for libxml2 trees would need quite a lot of work to 2152function properly, and rather than risk memory leaks if not implemented 2153correctly it sounds safer to have an explicit function to free a tree. The 2154wrapper python objects like doc, root or child are them automatically garbage 2155collected.</p> 2156 2157<h3>validate.py:</h3> 2158 2159<p>This test check the validation interfaces and redirection of error 2160messages:</p> 2161<pre>import libxml2 2162 2163#deactivate error messages from the validation 2164def noerr(ctx, str): 2165 pass 2166 2167libxml2.registerErrorHandler(noerr, None) 2168 2169ctxt = libxml2.createFileParserCtxt("invalid.xml") 2170ctxt.validate(1) 2171ctxt.parseDocument() 2172doc = ctxt.doc() 2173valid = ctxt.isValid() 2174doc.freeDoc() 2175if valid != 0: 2176 print "validity check failed"</pre> 2177 2178<p>The first thing to notice is the call to registerErrorHandler(), it 2179defines a new error handler global to the library. It is used to avoid seeing 2180the error messages when trying to validate the invalid document.</p> 2181 2182<p>The main interest of that test is the creation of a parser context with 2183createFileParserCtxt() and how the behaviour can be changed before calling 2184parseDocument() . Similarly the informations resulting from the parsing phase 2185are also available using context methods.</p> 2186 2187<p>Contexts like nodes are defined as class and the libxml2 wrappers maps the 2188C function interfaces in terms of objects method as much as possible. The 2189best to get a complete view of what methods are supported is to look at the 2190libxml2.py module containing all the wrappers.</p> 2191 2192<h3>push.py:</h3> 2193 2194<p>This test show how to activate the push parser interface:</p> 2195<pre>import libxml2 2196 2197ctxt = libxml2.createPushParser(None, "<foo", 4, "test.xml") 2198ctxt.parseChunk("/>", 2, 1) 2199doc = ctxt.doc() 2200 2201doc.freeDoc()</pre> 2202 2203<p>The context is created with a special call based on the 2204xmlCreatePushParser() from the C library. The first argument is an optional 2205SAX callback object, then the initial set of data, the length and the name of 2206the resource in case URI-References need to be computed by the parser.</p> 2207 2208<p>Then the data are pushed using the parseChunk() method, the last call 2209setting the third argument terminate to 1.</p> 2210 2211<h3>pushSAX.py:</h3> 2212 2213<p>this test show the use of the event based parsing interfaces. In this case 2214the parser does not build a document, but provides callback information as 2215the parser makes progresses analyzing the data being provided:</p> 2216<pre>import libxml2 2217log = "" 2218 2219class callback: 2220 def startDocument(self): 2221 global log 2222 log = log + "startDocument:" 2223 2224 def endDocument(self): 2225 global log 2226 log = log + "endDocument:" 2227 2228 def startElement(self, tag, attrs): 2229 global log 2230 log = log + "startElement %s %s:" % (tag, attrs) 2231 2232 def endElement(self, tag): 2233 global log 2234 log = log + "endElement %s:" % (tag) 2235 2236 def characters(self, data): 2237 global log 2238 log = log + "characters: %s:" % (data) 2239 2240 def warning(self, msg): 2241 global log 2242 log = log + "warning: %s:" % (msg) 2243 2244 def error(self, msg): 2245 global log 2246 log = log + "error: %s:" % (msg) 2247 2248 def fatalError(self, msg): 2249 global log 2250 log = log + "fatalError: %s:" % (msg) 2251 2252handler = callback() 2253 2254ctxt = libxml2.createPushParser(handler, "<foo", 4, "test.xml") 2255chunk = " url='tst'>b" 2256ctxt.parseChunk(chunk, len(chunk), 0) 2257chunk = "ar</foo>" 2258ctxt.parseChunk(chunk, len(chunk), 1) 2259 2260reference = "startDocument:startElement foo {'url': 'tst'}:" + \ 2261 "characters: bar:endElement foo:endDocument:" 2262if log != reference: 2263 print "Error got: %s" % log 2264 print "Expected: %s" % reference</pre> 2265 2266<p>The key object in that test is the handler, it provides a number of entry 2267points which can be called by the parser as it makes progresses to indicate 2268the information set obtained. The full set of callback is larger than what 2269the callback class in that specific example implements (see the SAX 2270definition for a complete list). The wrapper will only call those supplied by 2271the object when activated. The startElement receives the names of the element 2272and a dictionary containing the attributes carried by this element.</p> 2273 2274<p>Also note that the reference string generated from the callback shows a 2275single character call even though the string "bar" is passed to the parser 2276from 2 different call to parseChunk()</p> 2277 2278<h3>xpath.py:</h3> 2279 2280<p>This is a basic test of XPath wrappers support</p> 2281<pre>import libxml2 2282 2283doc = libxml2.parseFile("tst.xml") 2284ctxt = doc.xpathNewContext() 2285res = ctxt.xpathEval("//*") 2286if len(res) != 2: 2287 print "xpath query: wrong node set size" 2288 sys.exit(1) 2289if res[0].name != "doc" or res[1].name != "foo": 2290 print "xpath query: wrong node set value" 2291 sys.exit(1) 2292doc.freeDoc() 2293ctxt.xpathFreeContext()</pre> 2294 2295<p>This test parses a file, then create an XPath context to evaluate XPath 2296expression on it. The xpathEval() method execute an XPath query and returns 2297the result mapped in a Python way. String and numbers are natively converted, 2298and node sets are returned as a tuple of libxml2 Python nodes wrappers. Like 2299the document, the XPath context need to be freed explicitly, also not that 2300the result of the XPath query may point back to the document tree and hence 2301the document must be freed after the result of the query is used.</p> 2302 2303<h3>xpathext.py:</h3> 2304 2305<p>This test shows how to extend the XPath engine with functions written in 2306python:</p> 2307<pre>import libxml2 2308 2309def foo(ctx, x): 2310 return x + 1 2311 2312doc = libxml2.parseFile("tst.xml") 2313ctxt = doc.xpathNewContext() 2314libxml2.registerXPathFunction(ctxt._o, "foo", None, foo) 2315res = ctxt.xpathEval("foo(1)") 2316if res != 2: 2317 print "xpath extension failure" 2318doc.freeDoc() 2319ctxt.xpathFreeContext()</pre> 2320 2321<p>Note how the extension function is registered with the context (but that 2322part is not yet finalized, this may change slightly in the future).</p> 2323 2324<h3>tstxpath.py:</h3> 2325 2326<p>This test is similar to the previous one but shows how the extension 2327function can access the XPath evaluation context:</p> 2328<pre>def foo(ctx, x): 2329 global called 2330 2331 # 2332 # test that access to the XPath evaluation contexts 2333 # 2334 pctxt = libxml2.xpathParserContext(_obj=ctx) 2335 ctxt = pctxt.context() 2336 called = ctxt.function() 2337 return x + 1</pre> 2338 2339<p>All the interfaces around the XPath parser(or rather evaluation) context 2340are not finalized, but it should be sufficient to do contextual work at the 2341evaluation point.</p> 2342 2343<h3>Memory debugging:</h3> 2344 2345<p>last but not least, all tests starts with the following prologue:</p> 2346<pre>#memory debug specific 2347libxml2.debugMemory(1)</pre> 2348 2349<p>and ends with the following epilogue:</p> 2350<pre>#memory debug specific 2351libxml2.cleanupParser() 2352if libxml2.debugMemory(1) == 0: 2353 print "OK" 2354else: 2355 print "Memory leak %d bytes" % (libxml2.debugMemory(1)) 2356 libxml2.dumpMemory()</pre> 2357 2358<p>Those activate the memory debugging interface of libxml2 where all 2359allocated block in the library are tracked. The prologue then cleans up the 2360library state and checks that all allocated memory has been freed. If not it 2361calls dumpMemory() which saves that list in a <code>.memdump</code> file.</p> 2362 2363<h2><a name="architecture">libxml2 architecture</a></h2> 2364 2365<p>Libxml2 is made of multiple components; some of them are optional, and 2366most of the block interfaces are public. The main components are:</p> 2367<ul> 2368 <li>an Input/Output layer</li> 2369 <li>FTP and HTTP client layers (optional)</li> 2370 <li>an Internationalization layer managing the encodings support</li> 2371 <li>a URI module</li> 2372 <li>the XML parser and its basic SAX interface</li> 2373 <li>an HTML parser using the same SAX interface (optional)</li> 2374 <li>a SAX tree module to build an in-memory DOM representation</li> 2375 <li>a tree module to manipulate the DOM representation</li> 2376 <li>a validation module using the DOM representation (optional)</li> 2377 <li>an XPath module for global lookup in a DOM representation 2378 (optional)</li> 2379 <li>a debug module (optional)</li> 2380</ul> 2381 2382<p>Graphically this gives the following:</p> 2383 2384<p><img src="libxml.gif" alt="a graphical view of the various"></p> 2385 2386<p></p> 2387 2388<h2><a name="tree">The tree output</a></h2> 2389 2390<p>The parser returns a tree built during the document analysis. The value 2391returned is an <strong>xmlDocPtr</strong> (i.e., a pointer to an 2392<strong>xmlDoc</strong> structure). This structure contains information such 2393as the file name, the document type, and a <strong>children</strong> pointer 2394which is the root of the document (or more exactly the first child under the 2395root which is the document). The tree is made of <strong>xmlNode</strong>s, 2396chained in double-linked lists of siblings and with a children<->parent 2397relationship. An xmlNode can also carry properties (a chain of xmlAttr 2398structures). An attribute may have a value which is a list of TEXT or 2399ENTITY_REF nodes.</p> 2400 2401<p>Here is an example (erroneous with respect to the XML spec since there 2402should be only one ELEMENT under the root):</p> 2403 2404<p><img src="structure.gif" alt=" structure.gif "></p> 2405 2406<p>In the source package there is a small program (not installed by default) 2407called <strong>xmllint</strong> which parses XML files given as argument and 2408prints them back as parsed. This is useful for detecting errors both in XML 2409code and in the XML parser itself. It has an option <strong>--debug</strong> 2410which prints the actual in-memory structure of the document; here is the 2411result with the <a href="#example">example</a> given before:</p> 2412<pre>DOCUMENT 2413version=1.0 2414standalone=true 2415 ELEMENT EXAMPLE 2416 ATTRIBUTE prop1 2417 TEXT 2418 content=gnome is great 2419 ATTRIBUTE prop2 2420 ENTITY_REF 2421 TEXT 2422 content= linux too 2423 ELEMENT head 2424 ELEMENT title 2425 TEXT 2426 content=Welcome to Gnome 2427 ELEMENT chapter 2428 ELEMENT title 2429 TEXT 2430 content=The Linux adventure 2431 ELEMENT p 2432 TEXT 2433 content=bla bla bla ... 2434 ELEMENT image 2435 ATTRIBUTE href 2436 TEXT 2437 content=linus.gif 2438 ELEMENT p 2439 TEXT 2440 content=...</pre> 2441 2442<p>This should be useful for learning the internal representation model.</p> 2443 2444<h2><a name="interface">The SAX interface</a></h2> 2445 2446<p>Sometimes the DOM tree output is just too large to fit reasonably into 2447memory. In that case (and if you don't expect to save back the XML document 2448loaded using libxml), it's better to use the SAX interface of libxml. SAX is 2449a <strong>callback-based interface</strong> to the parser. Before parsing, 2450the application layer registers a customized set of callbacks which are 2451called by the library as it progresses through the XML input.</p> 2452 2453<p>To get more detailed step-by-step guidance on using the SAX interface of 2454libxml, see the <a 2455href="http://www.daa.com.au/~james/gnome/xml-sax/xml-sax.html">nice 2456documentation</a>.written by <a href="mailto:james@daa.com.au">James 2457Henstridge</a>.</p> 2458 2459<p>You can debug the SAX behaviour by using the <strong>testSAX</strong> 2460program located in the gnome-xml module (it's usually not shipped in the 2461binary packages of libxml, but you can find it in the tar source 2462distribution). Here is the sequence of callbacks that would be reported by 2463testSAX when parsing the example XML document shown earlier:</p> 2464<pre>SAX.setDocumentLocator() 2465SAX.startDocument() 2466SAX.getEntity(amp) 2467SAX.startElement(EXAMPLE, prop1='gnome is great', prop2='&amp; linux too') 2468SAX.characters( , 3) 2469SAX.startElement(head) 2470SAX.characters( , 4) 2471SAX.startElement(title) 2472SAX.characters(Welcome to Gnome, 16) 2473SAX.endElement(title) 2474SAX.characters( , 3) 2475SAX.endElement(head) 2476SAX.characters( , 3) 2477SAX.startElement(chapter) 2478SAX.characters( , 4) 2479SAX.startElement(title) 2480SAX.characters(The Linux adventure, 19) 2481SAX.endElement(title) 2482SAX.characters( , 4) 2483SAX.startElement(p) 2484SAX.characters(bla bla bla ..., 15) 2485SAX.endElement(p) 2486SAX.characters( , 4) 2487SAX.startElement(image, href='linus.gif') 2488SAX.endElement(image) 2489SAX.characters( , 4) 2490SAX.startElement(p) 2491SAX.characters(..., 3) 2492SAX.endElement(p) 2493SAX.characters( , 3) 2494SAX.endElement(chapter) 2495SAX.characters( , 1) 2496SAX.endElement(EXAMPLE) 2497SAX.endDocument()</pre> 2498 2499<p>Most of the other interfaces of libxml2 are based on the DOM tree-building 2500facility, so nearly everything up to the end of this document presupposes the 2501use of the standard DOM tree build. Note that the DOM tree itself is built by 2502a set of registered default callbacks, without internal specific 2503interface.</p> 2504 2505<h2><a name="Validation">Validation & DTDs</a></h2> 2506 2507<p>Table of Content:</p> 2508<ol> 2509 <li><a href="#General5">General overview</a></li> 2510 <li><a href="#definition">The definition</a></li> 2511 <li><a href="#Simple">Simple rules</a> 2512 <ol> 2513 <li><a href="#reference">How to reference a DTD from a document</a></li> 2514 <li><a href="#Declaring">Declaring elements</a></li> 2515 <li><a href="#Declaring1">Declaring attributes</a></li> 2516 </ol> 2517 </li> 2518 <li><a href="#Some">Some examples</a></li> 2519 <li><a href="#validate">How to validate</a></li> 2520 <li><a href="#Other">Other resources</a></li> 2521</ol> 2522 2523<h3><a name="General5">General overview</a></h3> 2524 2525<p>Well what is validation and what is a DTD ?</p> 2526 2527<p>DTD is the acronym for Document Type Definition. This is a description of 2528the content for a family of XML files. This is part of the XML 1.0 2529specification, and allows one to describe and verify that a given document 2530instance conforms to the set of rules detailing its structure and content.</p> 2531 2532<p>Validation is the process of checking a document against a DTD (more 2533generally against a set of construction rules).</p> 2534 2535<p>The validation process and building DTDs are the two most difficult parts 2536of the XML life cycle. Briefly a DTD defines all the possible elements to be 2537found within your document, what is the formal shape of your document tree 2538(by defining the allowed content of an element; either text, a regular 2539expression for the allowed list of children, or mixed content i.e. both text 2540and children). The DTD also defines the valid attributes for all elements and 2541the types of those attributes.</p> 2542 2543<h3><a name="definition1">The definition</a></h3> 2544 2545<p>The <a href="http://www.w3.org/TR/REC-xml">W3C XML Recommendation</a> (<a 2546href="http://www.xml.com/axml/axml.html">Tim Bray's annotated version of 2547Rev1</a>):</p> 2548<ul> 2549 <li><a href="http://www.w3.org/TR/REC-xml#elemdecls">Declaring 2550 elements</a></li> 2551 <li><a href="http://www.w3.org/TR/REC-xml#attdecls">Declaring 2552 attributes</a></li> 2553</ul> 2554 2555<p>(unfortunately) all this is inherited from the SGML world, the syntax is 2556ancient...</p> 2557 2558<h3><a name="Simple1">Simple rules</a></h3> 2559 2560<p>Writing DTDs can be done in many ways. The rules to build them if you need 2561something permanent or something which can evolve over time can be radically 2562different. Really complex DTDs like DocBook ones are flexible but quite 2563harder to design. I will just focus on DTDs for a formats with a fixed simple 2564structure. It is just a set of basic rules, and definitely not exhaustive nor 2565usable for complex DTD design.</p> 2566 2567<h4><a name="reference1">How to reference a DTD from a document</a>:</h4> 2568 2569<p>Assuming the top element of the document is <code>spec</code> and the dtd 2570is placed in the file <code>mydtd</code> in the subdirectory 2571<code>dtds</code> of the directory from where the document were loaded:</p> 2572 2573<p><code><!DOCTYPE spec SYSTEM "dtds/mydtd"></code></p> 2574 2575<p>Notes:</p> 2576<ul> 2577 <li>The system string is actually an URI-Reference (as defined in <a 2578 href="http://www.ietf.org/rfc/rfc2396.txt">RFC 2396</a>) so you can use a 2579 full URL string indicating the location of your DTD on the Web. This is a 2580 really good thing to do if you want others to validate your document.</li> 2581 <li>It is also possible to associate a <code>PUBLIC</code> identifier (a 2582 magic string) so that the DTD is looked up in catalogs on the client side 2583 without having to locate it on the web.</li> 2584 <li>A DTD contains a set of element and attribute declarations, but they 2585 don't define what the root of the document should be. This is explicitly 2586 told to the parser/validator as the first element of the 2587 <code>DOCTYPE</code> declaration.</li> 2588</ul> 2589 2590<h4><a name="Declaring2">Declaring elements</a>:</h4> 2591 2592<p>The following declares an element <code>spec</code>:</p> 2593 2594<p><code><!ELEMENT spec (front, body, back?)></code></p> 2595 2596<p>It also expresses that the spec element contains one <code>front</code>, 2597one <code>body</code> and one optional <code>back</code> children elements in 2598this order. The declaration of one element of the structure and its content 2599are done in a single declaration. Similarly the following declares 2600<code>div1</code> elements:</p> 2601 2602<p><code><!ELEMENT div1 (head, (p | list | note)*, div2?)></code></p> 2603 2604<p>which means div1 contains one <code>head</code> then a series of optional 2605<code>p</code>, <code>list</code>s and <code>note</code>s and then an 2606optional <code>div2</code>. And last but not least an element can contain 2607text:</p> 2608 2609<p><code><!ELEMENT b (#PCDATA)></code></p> 2610 2611<p><code>b</code> contains text or being of mixed content (text and elements 2612in no particular order):</p> 2613 2614<p><code><!ELEMENT p (#PCDATA|a|ul|b|i|em)*></code></p> 2615 2616<p><code>p </code>can contain text or <code>a</code>, <code>ul</code>, 2617<code>b</code>, <code>i </code>or <code>em</code> elements in no particular 2618order.</p> 2619 2620<h4><a name="Declaring1">Declaring attributes</a>:</h4> 2621 2622<p>Again the attributes declaration includes their content definition:</p> 2623 2624<p><code><!ATTLIST termdef name CDATA #IMPLIED></code></p> 2625 2626<p>means that the element <code>termdef</code> can have a <code>name</code> 2627attribute containing text (<code>CDATA</code>) and which is optional 2628(<code>#IMPLIED</code>). The attribute value can also be defined within a 2629set:</p> 2630 2631<p><code><!ATTLIST list type (bullets|ordered|glossary) 2632"ordered"></code></p> 2633 2634<p>means <code>list</code> element have a <code>type</code> attribute with 3 2635allowed values "bullets", "ordered" or "glossary" and which default to 2636"ordered" if the attribute is not explicitly specified.</p> 2637 2638<p>The content type of an attribute can be text (<code>CDATA</code>), 2639anchor/reference/references 2640(<code>ID</code>/<code>IDREF</code>/<code>IDREFS</code>), entity(ies) 2641(<code>ENTITY</code>/<code>ENTITIES</code>) or name(s) 2642(<code>NMTOKEN</code>/<code>NMTOKENS</code>). The following defines that a 2643<code>chapter</code> element can have an optional <code>id</code> attribute 2644of type <code>ID</code>, usable for reference from attribute of type 2645IDREF:</p> 2646 2647<p><code><!ATTLIST chapter id ID #IMPLIED></code></p> 2648 2649<p>The last value of an attribute definition can be <code>#REQUIRED 2650</code>meaning that the attribute has to be given, <code>#IMPLIED</code> 2651meaning that it is optional, or the default value (possibly prefixed by 2652<code>#FIXED</code> if it is the only allowed).</p> 2653 2654<p>Notes:</p> 2655<ul> 2656 <li>Usually the attributes pertaining to a given element are declared in a 2657 single expression, but it is just a convention adopted by a lot of DTD 2658 writers: 2659 <pre><!ATTLIST termdef 2660 id ID #REQUIRED 2661 name CDATA #IMPLIED></pre> 2662 <p>The previous construct defines both <code>id</code> and 2663 <code>name</code> attributes for the element <code>termdef</code>.</p> 2664 </li> 2665</ul> 2666 2667<h3><a name="Some1">Some examples</a></h3> 2668 2669<p>The directory <code>test/valid/dtds/</code> in the libxml2 distribution 2670contains some complex DTD examples. The example in the file 2671<code>test/valid/dia.xml</code> shows an XML file where the simple DTD is 2672directly included within the document.</p> 2673 2674<h3><a name="validate1">How to validate</a></h3> 2675 2676<p>The simplest way is to use the xmllint program included with libxml. The 2677<code>--valid</code> option turns-on validation of the files given as input. 2678For example the following validates a copy of the first revision of the XML 26791.0 specification:</p> 2680 2681<p><code>xmllint --valid --noout test/valid/REC-xml-19980210.xml</code></p> 2682 2683<p>the -- noout is used to disable output of the resulting tree.</p> 2684 2685<p>The <code>--dtdvalid dtd</code> allows validation of the document(s) 2686against a given DTD.</p> 2687 2688<p>Libxml2 exports an API to handle DTDs and validation, check the <a 2689href="http://xmlsoft.org/html/libxml-valid.html">associated 2690description</a>.</p> 2691 2692<h3><a name="Other1">Other resources</a></h3> 2693 2694<p>DTDs are as old as SGML. So there may be a number of examples on-line, I 2695will just list one for now, others pointers welcome:</p> 2696<ul> 2697 <li><a href="http://www.xml101.com:8081/dtd/">XML-101 DTD</a></li> 2698</ul> 2699 2700<p>I suggest looking at the examples found under test/valid/dtd and any of 2701the large number of books available on XML. The dia example in test/valid 2702should be both simple and complete enough to allow you to build your own.</p> 2703 2704<p></p> 2705 2706<h2><a name="Memory">Memory Management</a></h2> 2707 2708<p>Table of Content:</p> 2709<ol> 2710 <li><a href="#General3">General overview</a></li> 2711 <li><a href="#setting">Setting libxml2 set of memory routines</a></li> 2712 <li><a href="#cleanup">Cleaning up after parsing</a></li> 2713 <li><a href="#Debugging">Debugging routines</a></li> 2714 <li><a href="#General4">General memory requirements</a></li> 2715</ol> 2716 2717<h3><a name="General3">General overview</a></h3> 2718 2719<p>The module <code><a 2720href="http://xmlsoft.org/html/libxml-xmlmemory.html">xmlmemory.h</a></code> 2721provides the interfaces to the libxml2 memory system:</p> 2722<ul> 2723 <li>libxml2 does not use the libc memory allocator directly but xmlFree(), 2724 xmlMalloc() and xmlRealloc()</li> 2725 <li>those routines can be reallocated to a specific set of routine, by 2726 default the libc ones i.e. free(), malloc() and realloc()</li> 2727 <li>the xmlmemory.c module includes a set of debugging routine</li> 2728</ul> 2729 2730<h3><a name="setting">Setting libxml2 set of memory routines</a></h3> 2731 2732<p>It is sometimes useful to not use the default memory allocator, either for 2733debugging, analysis or to implement a specific behaviour on memory management 2734(like on embedded systems). Two function calls are available to do so:</p> 2735<ul> 2736 <li><a href="http://xmlsoft.org/html/libxml-xmlmemory.html">xmlMemGet 2737 ()</a> which return the current set of functions in use by the parser</li> 2738 <li><a 2739 href="http://xmlsoft.org/html/libxml-xmlmemory.html">xmlMemSetup()</a> 2740 which allow to set up a new set of memory allocation functions</li> 2741</ul> 2742 2743<p>Of course a call to xmlMemSetup() should probably be done before calling 2744any other libxml2 routines (unless you are sure your allocations routines are 2745compatibles).</p> 2746 2747<h3><a name="cleanup">Cleaning up after parsing</a></h3> 2748 2749<p>Libxml2 is not stateless, there is a few set of memory structures needing 2750allocation before the parser is fully functional (some encoding structures 2751for example). This also mean that once parsing is finished there is a tiny 2752amount of memory (a few hundred bytes) which can be recollected if you don't 2753reuse the parser immediately:</p> 2754<ul> 2755 <li><a href="http://xmlsoft.org/html/libxml-parser.html">xmlCleanupParser 2756 ()</a> is a centralized routine to free the parsing states. Note that it 2757 won't deallocate any produced tree if any (use the xmlFreeDoc() and 2758 related routines for this).</li> 2759 <li><a href="http://xmlsoft.org/html/libxml-parser.html">xmlInitParser 2760 ()</a> is the dual routine allowing to preallocate the parsing state 2761 which can be useful for example to avoid initialization reentrancy 2762 problems when using libxml2 in multithreaded applications</li> 2763</ul> 2764 2765<p>Generally xmlCleanupParser() is safe, if needed the state will be rebuild 2766at the next invocation of parser routines, but be careful of the consequences 2767in multithreaded applications.</p> 2768 2769<h3><a name="Debugging">Debugging routines</a></h3> 2770 2771<p>When configured using --with-mem-debug flag (off by default), libxml2 uses 2772a set of memory allocation debugging routines keeping track of all allocated 2773blocks and the location in the code where the routine was called. A couple of 2774other debugging routines allow to dump the memory allocated infos to a file 2775or call a specific routine when a given block number is allocated:</p> 2776<ul> 2777 <li><a 2778 href="http://xmlsoft.org/html/libxml-xmlmemory.html">xmlMallocLoc()</a> 2779 <a 2780 href="http://xmlsoft.org/html/libxml-xmlmemory.html">xmlReallocLoc()</a> 2781 and <a 2782 href="http://xmlsoft.org/html/libxml-xmlmemory.html">xmlMemStrdupLoc()</a> 2783 are the memory debugging replacement allocation routines</li> 2784 <li><a href="http://xmlsoft.org/html/libxml-xmlmemory.html">xmlMemoryDump 2785 ()</a> dumps all the informations about the allocated memory block lefts 2786 in the <code>.memdump</code> file</li> 2787</ul> 2788 2789<p>When developing libxml2 memory debug is enabled, the tests programs call 2790xmlMemoryDump () and the "make test" regression tests will check for any 2791memory leak during the full regression test sequence, this helps a lot 2792ensuring that libxml2 does not leak memory and bullet proof memory 2793allocations use (some libc implementations are known to be far too permissive 2794resulting in major portability problems!).</p> 2795 2796<p>If the .memdump reports a leak, it displays the allocation function and 2797also tries to give some informations about the content and structure of the 2798allocated blocks left. This is sufficient in most cases to find the culprit, 2799but not always. Assuming the allocation problem is reproducible, it is 2800possible to find more easily:</p> 2801<ol> 2802 <li>write down the block number xxxx not allocated</li> 2803 <li>export the environment variable XML_MEM_BREAKPOINT=xxxx , the easiest 2804 when using GDB is to simply give the command 2805 <p><code>set environment XML_MEM_BREAKPOINT xxxx</code></p> 2806 <p>before running the program.</p> 2807 </li> 2808 <li>run the program under a debugger and set a breakpoint on 2809 xmlMallocBreakpoint() a specific function called when this precise block 2810 is allocated</li> 2811 <li>when the breakpoint is reached you can then do a fine analysis of the 2812 allocation an step to see the condition resulting in the missing 2813 deallocation.</li> 2814</ol> 2815 2816<p>I used to use a commercial tool to debug libxml2 memory problems but after 2817noticing that it was not detecting memory leaks that simple mechanism was 2818used and proved extremely efficient until now. Lately I have also used <a 2819href="http://developer.kde.org/~sewardj/">valgrind</a> with quite some 2820success, it is tied to the i386 architecture since it works by emulating the 2821processor and instruction set, it is slow but extremely efficient, i.e. it 2822spot memory usage errors in a very precise way.</p> 2823 2824<h3><a name="General4">General memory requirements</a></h3> 2825 2826<p>How much libxml2 memory require ? It's hard to tell in average it depends 2827of a number of things:</p> 2828<ul> 2829 <li>the parser itself should work in a fixed amount of memory, except for 2830 information maintained about the stacks of names and entities locations. 2831 The I/O and encoding handlers will probably account for a few KBytes. 2832 This is true for both the XML and HTML parser (though the HTML parser 2833 need more state).</li> 2834 <li>If you are generating the DOM tree then memory requirements will grow 2835 nearly linear with the size of the data. In general for a balanced 2836 textual document the internal memory requirement is about 4 times the 2837 size of the UTF8 serialization of this document (example the XML-1.0 2838 recommendation is a bit more of 150KBytes and takes 650KBytes of main 2839 memory when parsed). Validation will add a amount of memory required for 2840 maintaining the external Dtd state which should be linear with the 2841 complexity of the content model defined by the Dtd</li> 2842 <li>If you need to work with fixed memory requirements or don't need the 2843 full DOM tree then using the <a href="xmlreader.html">xmlReader 2844 interface</a> is probably the best way to proceed, it still allows to 2845 validate or operate on subset of the tree if needed.</li> 2846 <li>If you don't care about the advanced features of libxml2 like 2847 validation, DOM, XPath or XPointer, don't use entities, need to work with 2848 fixed memory requirements, and try to get the fastest parsing possible 2849 then the SAX interface should be used, but it has known restrictions.</li> 2850</ul> 2851 2852<p></p> 2853 2854<h2><a name="Encodings">Encodings support</a></h2> 2855 2856<p>Table of Content:</p> 2857<ol> 2858 <li><a href="encoding.html#What">What does internationalization support 2859 mean ?</a></li> 2860 <li><a href="encoding.html#internal">The internal encoding, how and 2861 why</a></li> 2862 <li><a href="encoding.html#implemente">How is it implemented ?</a></li> 2863 <li><a href="encoding.html#Default">Default supported encodings</a></li> 2864 <li><a href="encoding.html#extend">How to extend the existing 2865 support</a></li> 2866</ol> 2867 2868<h3><a name="What">What does internationalization support mean ?</a></h3> 2869 2870<p>If you are not really familiar with Internationalization (usual shortcut 2871is I18N) , Unicode, characters and glyphs, I suggest you read a <a 2872href="http://www.tbray.org/ongoing/When/200x/2003/04/06/Unicode">presentation</a> 2873by Tim Bray on Unicode and why you should care about it.</p> 2874 2875<p>XML was designed from the start to allow the support of any character set 2876by using Unicode. Any conformant XML parser has to support the UTF-8 and 2877UTF-16 default encodings which can both express the full unicode ranges. UTF8 2878is a variable length encoding whose greatest points are to reuse the same 2879encoding for ASCII and to save space for Western encodings, but it is a bit 2880more complex to handle in practice. UTF-16 use 2 bytes per character (and 2881sometimes combines two pairs), it makes implementation easier, but looks a 2882bit overkill for Western languages encoding. Moreover the XML specification 2883allows the document to be encoded in other encodings at the condition that 2884they are clearly labeled as such. For example the following is a wellformed 2885XML document encoded in ISO-8859-1 and using accentuated letters that we 2886French like for both markup and content:</p> 2887<pre><?xml version="1.0" encoding="ISO-8859-1"?> 2888<tr�s>l�</tr�s></pre> 2889 2890<p>Having internationalization support in libxml2 means the following:</p> 2891<ul> 2892 <li>the document is properly parsed</li> 2893 <li>informations about it's encoding are saved</li> 2894 <li>it can be modified</li> 2895 <li>it can be saved in its original encoding</li> 2896 <li>it can also be saved in another encoding supported by libxml2 (for 2897 example straight UTF8 or even an ASCII form)</li> 2898</ul> 2899 2900<p>Another very important point is that the whole libxml2 API, with the 2901exception of a few routines to read with a specific encoding or save to a 2902specific encoding, is completely agnostic about the original encoding of the 2903document.</p> 2904 2905<p>It should be noted too that the HTML parser embedded in libxml2 now obey 2906the same rules too, the following document will be (as of 2.2.2) handled in 2907an internationalized fashion by libxml2 too:</p> 2908<pre><!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN" 2909 "http://www.w3.org/TR/REC-html40/loose.dtd"> 2910<html lang="fr"> 2911<head> 2912 <META HTTP-EQUIV="Content-Type" CONTENT="text/html; charset=ISO-8859-1"> 2913</head> 2914<body> 2915<p>W3C cr�e des standards pour le Web.</body> 2916</html></pre> 2917 2918<h3><a name="internal">The internal encoding, how and why</a></h3> 2919 2920<p>One of the core decisions was to force all documents to be converted to a 2921default internal encoding, and that encoding to be UTF-8, here are the 2922rationales for those choices:</p> 2923<ul> 2924 <li>keeping the native encoding in the internal form would force the libxml 2925 users (or the code associated) to be fully aware of the encoding of the 2926 original document, for examples when adding a text node to a document, 2927 the content would have to be provided in the document encoding, i.e. the 2928 client code would have to check it before hand, make sure it's conformant 2929 to the encoding, etc ... Very hard in practice, though in some specific 2930 cases this may make sense.</li> 2931 <li>the second decision was which encoding. From the XML spec only UTF8 and 2932 UTF16 really makes sense as being the two only encodings for which there 2933 is mandatory support. UCS-4 (32 bits fixed size encoding) could be 2934 considered an intelligent choice too since it's a direct Unicode mapping 2935 support. I selected UTF-8 on the basis of efficiency and compatibility 2936 with surrounding software: 2937 <ul> 2938 <li>UTF-8 while a bit more complex to convert from/to (i.e. slightly 2939 more costly to import and export CPU wise) is also far more compact 2940 than UTF-16 (and UCS-4) for a majority of the documents I see it used 2941 for right now (RPM RDF catalogs, advogato data, various configuration 2942 file formats, etc.) and the key point for today's computer 2943 architecture is efficient uses of caches. If one nearly double the 2944 memory requirement to store the same amount of data, this will trash 2945 caches (main memory/external caches/internal caches) and my take is 2946 that this harms the system far more than the CPU requirements needed 2947 for the conversion to UTF-8</li> 2948 <li>Most of libxml2 version 1 users were using it with straight ASCII 2949 most of the time, doing the conversion with an internal encoding 2950 requiring all their code to be rewritten was a serious show-stopper 2951 for using UTF-16 or UCS-4.</li> 2952 <li>UTF-8 is being used as the de-facto internal encoding standard for 2953 related code like the <a href="http://www.pango.org/">pango</a> 2954 upcoming Gnome text widget, and a lot of Unix code (yet another place 2955 where Unix programmer base takes a different approach from Microsoft 2956 - they are using UTF-16)</li> 2957 </ul> 2958 </li> 2959</ul> 2960 2961<p>What does this mean in practice for the libxml2 user:</p> 2962<ul> 2963 <li>xmlChar, the libxml2 data type is a byte, those bytes must be assembled 2964 as UTF-8 valid strings. The proper way to terminate an xmlChar * string 2965 is simply to append 0 byte, as usual.</li> 2966 <li>One just need to make sure that when using chars outside the ASCII set, 2967 the values has been properly converted to UTF-8</li> 2968</ul> 2969 2970<h3><a name="implemente">How is it implemented ?</a></h3> 2971 2972<p>Let's describe how all this works within libxml, basically the I18N 2973(internationalization) support get triggered only during I/O operation, i.e. 2974when reading a document or saving one. Let's look first at the reading 2975sequence:</p> 2976<ol> 2977 <li>when a document is processed, we usually don't know the encoding, a 2978 simple heuristic allows to detect UTF-16 and UCS-4 from encodings where 2979 the ASCII range (0-0x7F) maps with ASCII</li> 2980 <li>the xml declaration if available is parsed, including the encoding 2981 declaration. At that point, if the autodetected encoding is different 2982 from the one declared a call to xmlSwitchEncoding() is issued.</li> 2983 <li>If there is no encoding declaration, then the input has to be in either 2984 UTF-8 or UTF-16, if it is not then at some point when processing the 2985 input, the converter/checker of UTF-8 form will raise an encoding error. 2986 You may end-up with a garbled document, or no document at all ! Example: 2987 <pre>~/XML -> /xmllint err.xml 2988err.xml:1: error: Input is not proper UTF-8, indicate encoding ! 2989<tr�s>l�</tr�s> 2990 ^ 2991err.xml:1: error: Bytes: 0xE8 0x73 0x3E 0x6C 2992<tr�s>l�</tr�s> 2993 ^</pre> 2994 </li> 2995 <li>xmlSwitchEncoding() does an encoding name lookup, canonicalize it, and 2996 then search the default registered encoding converters for that encoding. 2997 If it's not within the default set and iconv() support has been compiled 2998 it, it will ask iconv for such an encoder. If this fails then the parser 2999 will report an error and stops processing: 3000 <pre>~/XML -> /xmllint err2.xml 3001err2.xml:1: error: Unsupported encoding UnsupportedEnc 3002<?xml version="1.0" encoding="UnsupportedEnc"?> 3003 ^</pre> 3004 </li> 3005 <li>From that point the encoder processes progressively the input (it is 3006 plugged as a front-end to the I/O module) for that entity. It captures 3007 and converts on-the-fly the document to be parsed to UTF-8. The parser 3008 itself just does UTF-8 checking of this input and process it 3009 transparently. The only difference is that the encoding information has 3010 been added to the parsing context (more precisely to the input 3011 corresponding to this entity).</li> 3012 <li>The result (when using DOM) is an internal form completely in UTF-8 3013 with just an encoding information on the document node.</li> 3014</ol> 3015 3016<p>Ok then what happens when saving the document (assuming you 3017collected/built an xmlDoc DOM like structure) ? It depends on the function 3018called, xmlSaveFile() will just try to save in the original encoding, while 3019xmlSaveFileTo() and xmlSaveFileEnc() can optionally save to a given 3020encoding:</p> 3021<ol> 3022 <li>if no encoding is given, libxml2 will look for an encoding value 3023 associated to the document and if it exists will try to save to that 3024 encoding, 3025 <p>otherwise everything is written in the internal form, i.e. UTF-8</p> 3026 </li> 3027 <li>so if an encoding was specified, either at the API level or on the 3028 document, libxml2 will again canonicalize the encoding name, lookup for a 3029 converter in the registered set or through iconv. If not found the 3030 function will return an error code</li> 3031 <li>the converter is placed before the I/O buffer layer, as another kind of 3032 buffer, then libxml2 will simply push the UTF-8 serialization to through 3033 that buffer, which will then progressively be converted and pushed onto 3034 the I/O layer.</li> 3035 <li>It is possible that the converter code fails on some input, for example 3036 trying to push an UTF-8 encoded Chinese character through the UTF-8 to 3037 ISO-8859-1 converter won't work. Since the encoders are progressive they 3038 will just report the error and the number of bytes converted, at that 3039 point libxml2 will decode the offending character, remove it from the 3040 buffer and replace it with the associated charRef encoding &#123; and 3041 resume the conversion. This guarantees that any document will be saved 3042 without losses (except for markup names where this is not legal, this is 3043 a problem in the current version, in practice avoid using non-ascii 3044 characters for tag or attribute names). A special "ascii" encoding name 3045 is used to save documents to a pure ascii form can be used when 3046 portability is really crucial</li> 3047</ol> 3048 3049<p>Here are a few examples based on the same test document:</p> 3050<pre>~/XML -> /xmllint isolat1 3051<?xml version="1.0" encoding="ISO-8859-1"?> 3052<tr�s>l�</tr�s> 3053~/XML -> /xmllint --encode UTF-8 isolat1 3054<?xml version="1.0" encoding="UTF-8"?> 3055<très>l� �</très> 3056~/XML -> </pre> 3057 3058<p>The same processing is applied (and reuse most of the code) for HTML I18N 3059processing. Looking up and modifying the content encoding is a bit more 3060difficult since it is located in a <meta> tag under the <head>, 3061so a couple of functions htmlGetMetaEncoding() and htmlSetMetaEncoding() have 3062been provided. The parser also attempts to switch encoding on the fly when 3063detecting such a tag on input. Except for that the processing is the same 3064(and again reuses the same code).</p> 3065 3066<h3><a name="Default">Default supported encodings</a></h3> 3067 3068<p>libxml2 has a set of default converters for the following encodings 3069(located in encoding.c):</p> 3070<ol> 3071 <li>UTF-8 is supported by default (null handlers)</li> 3072 <li>UTF-16, both little and big endian</li> 3073 <li>ISO-Latin-1 (ISO-8859-1) covering most western languages</li> 3074 <li>ASCII, useful mostly for saving</li> 3075 <li>HTML, a specific handler for the conversion of UTF-8 to ASCII with HTML 3076 predefined entities like &copy; for the Copyright sign.</li> 3077</ol> 3078 3079<p>More over when compiled on an Unix platform with iconv support the full 3080set of encodings supported by iconv can be instantly be used by libxml. On a 3081linux machine with glibc-2.1 the list of supported encodings and aliases fill 30823 full pages, and include UCS-4, the full set of ISO-Latin encodings, and the 3083various Japanese ones.</p> 3084 3085<h4>Encoding aliases</h4> 3086 3087<p>From 2.2.3, libxml2 has support to register encoding names aliases. The 3088goal is to be able to parse document whose encoding is supported but where 3089the name differs (for example from the default set of names accepted by 3090iconv). The following functions allow to register and handle new aliases for 3091existing encodings. Once registered libxml2 will automatically lookup the 3092aliases when handling a document:</p> 3093<ul> 3094 <li>int xmlAddEncodingAlias(const char *name, const char *alias);</li> 3095 <li>int xmlDelEncodingAlias(const char *alias);</li> 3096 <li>const char * xmlGetEncodingAlias(const char *alias);</li> 3097 <li>void xmlCleanupEncodingAliases(void);</li> 3098</ul> 3099 3100<h3><a name="extend">How to extend the existing support</a></h3> 3101 3102<p>Well adding support for new encoding, or overriding one of the encoders 3103(assuming it is buggy) should not be hard, just write input and output 3104conversion routines to/from UTF-8, and register them using 3105xmlNewCharEncodingHandler(name, xxxToUTF8, UTF8Toxxx), and they will be 3106called automatically if the parser(s) encounter such an encoding name 3107(register it uppercase, this will help). The description of the encoders, 3108their arguments and expected return values are described in the encoding.h 3109header.</p> 3110 3111<p>A quick note on the topic of subverting the parser to use a different 3112internal encoding than UTF-8, in some case people will absolutely want to 3113keep the internal encoding different, I think it's still possible (but the 3114encoding must be compliant with ASCII on the same subrange) though I didn't 3115tried it. The key is to override the default conversion routines (by 3116registering null encoders/decoders for your charsets), and bypass the UTF-8 3117checking of the parser by setting the parser context charset 3118(ctxt->charset) to something different than XML_CHAR_ENCODING_UTF8, but 3119there is no guarantee that this will work. You may also have some troubles 3120saving back.</p> 3121 3122<p>Basically proper I18N support is important, this requires at least 3123libxml-2.0.0, but a lot of features and corrections are really available only 3124starting 2.2.</p> 3125 3126<h2><a name="IO">I/O Interfaces</a></h2> 3127 3128<p>Table of Content:</p> 3129<ol> 3130 <li><a href="#General1">General overview</a></li> 3131 <li><a href="#basic">The basic buffer type</a></li> 3132 <li><a href="#Input">Input I/O handlers</a></li> 3133 <li><a href="#Output">Output I/O handlers</a></li> 3134 <li><a href="#entities">The entities loader</a></li> 3135 <li><a href="#Example2">Example of customized I/O</a></li> 3136</ol> 3137 3138<h3><a name="General1">General overview</a></h3> 3139 3140<p>The module <code><a 3141href="http://xmlsoft.org/html/libxml-xmlio.html">xmlIO.h</a></code> provides 3142the interfaces to the libxml2 I/O system. This consists of 4 main parts:</p> 3143<ul> 3144 <li>Entities loader, this is a routine which tries to fetch the entities 3145 (files) based on their PUBLIC and SYSTEM identifiers. The default loader 3146 don't look at the public identifier since libxml2 do not maintain a 3147 catalog. You can redefine you own entity loader by using 3148 <code>xmlGetExternalEntityLoader()</code> and 3149 <code>xmlSetExternalEntityLoader()</code>. <a href="#entities">Check the 3150 example</a>.</li> 3151 <li>Input I/O buffers which are a commodity structure used by the parser(s) 3152 input layer to handle fetching the informations to feed the parser. This 3153 provides buffering and is also a placeholder where the encoding 3154 converters to UTF8 are piggy-backed.</li> 3155 <li>Output I/O buffers are similar to the Input ones and fulfill similar 3156 task but when generating a serialization from a tree.</li> 3157 <li>A mechanism to register sets of I/O callbacks and associate them with 3158 specific naming schemes like the protocol part of the URIs. 3159 <p>This affect the default I/O operations and allows to use specific I/O 3160 handlers for certain names.</p> 3161 </li> 3162</ul> 3163 3164<p>The general mechanism used when loading http://rpmfind.net/xml.html for 3165example in the HTML parser is the following:</p> 3166<ol> 3167 <li>The default entity loader calls <code>xmlNewInputFromFile()</code> with 3168 the parsing context and the URI string.</li> 3169 <li>the URI string is checked against the existing registered handlers 3170 using their match() callback function, if the HTTP module was compiled 3171 in, it is registered and its match() function will succeeds</li> 3172 <li>the open() function of the handler is called and if successful will 3173 return an I/O Input buffer</li> 3174 <li>the parser will the start reading from this buffer and progressively 3175 fetch information from the resource, calling the read() function of the 3176 handler until the resource is exhausted</li> 3177 <li>if an encoding change is detected it will be installed on the input 3178 buffer, providing buffering and efficient use of the conversion 3179 routines</li> 3180 <li>once the parser has finished, the close() function of the handler is 3181 called once and the Input buffer and associated resources are 3182 deallocated.</li> 3183</ol> 3184 3185<p>The user defined callbacks are checked first to allow overriding of the 3186default libxml2 I/O routines.</p> 3187 3188<h3><a name="basic">The basic buffer type</a></h3> 3189 3190<p>All the buffer manipulation handling is done using the 3191<code>xmlBuffer</code> type define in <code><a 3192href="http://xmlsoft.org/html/libxml-tree.html">tree.h</a> </code>which is a 3193resizable memory buffer. The buffer allocation strategy can be selected to be 3194either best-fit or use an exponential doubling one (CPU vs. memory use 3195trade-off). The values are <code>XML_BUFFER_ALLOC_EXACT</code> and 3196<code>XML_BUFFER_ALLOC_DOUBLEIT</code>, and can be set individually or on a 3197system wide basis using <code>xmlBufferSetAllocationScheme()</code>. A number 3198of functions allows to manipulate buffers with names starting with the 3199<code>xmlBuffer...</code> prefix.</p> 3200 3201<h3><a name="Input">Input I/O handlers</a></h3> 3202 3203<p>An Input I/O handler is a simple structure 3204<code>xmlParserInputBuffer</code> containing a context associated to the 3205resource (file descriptor, or pointer to a protocol handler), the read() and 3206close() callbacks to use and an xmlBuffer. And extra xmlBuffer and a charset 3207encoding handler are also present to support charset conversion when 3208needed.</p> 3209 3210<h3><a name="Output">Output I/O handlers</a></h3> 3211 3212<p>An Output handler <code>xmlOutputBuffer</code> is completely similar to an 3213Input one except the callbacks are write() and close().</p> 3214 3215<h3><a name="entities">The entities loader</a></h3> 3216 3217<p>The entity loader resolves requests for new entities and create inputs for 3218the parser. Creating an input from a filename or an URI string is done 3219through the xmlNewInputFromFile() routine. The default entity loader do not 3220handle the PUBLIC identifier associated with an entity (if any). So it just 3221calls xmlNewInputFromFile() with the SYSTEM identifier (which is mandatory in 3222XML).</p> 3223 3224<p>If you want to hook up a catalog mechanism then you simply need to 3225override the default entity loader, here is an example:</p> 3226<pre>#include <libxml/xmlIO.h> 3227 3228xmlExternalEntityLoader defaultLoader = NULL; 3229 3230xmlParserInputPtr 3231xmlMyExternalEntityLoader(const char *URL, const char *ID, 3232 xmlParserCtxtPtr ctxt) { 3233 xmlParserInputPtr ret; 3234 const char *fileID = NULL; 3235 /* lookup for the fileID depending on ID */ 3236 3237 ret = xmlNewInputFromFile(ctxt, fileID); 3238 if (ret != NULL) 3239 return(ret); 3240 if (defaultLoader != NULL) 3241 ret = defaultLoader(URL, ID, ctxt); 3242 return(ret); 3243} 3244 3245int main(..) { 3246 ... 3247 3248 /* 3249 * Install our own entity loader 3250 */ 3251 defaultLoader = xmlGetExternalEntityLoader(); 3252 xmlSetExternalEntityLoader(xmlMyExternalEntityLoader); 3253 3254 ... 3255}</pre> 3256 3257<h3><a name="Example2">Example of customized I/O</a></h3> 3258 3259<p>This example come from <a href="http://xmlsoft.org/messages/0708.html">a 3260real use case</a>, xmlDocDump() closes the FILE * passed by the application 3261and this was a problem. The <a 3262href="http://xmlsoft.org/messages/0711.html">solution</a> was to redefine a 3263new output handler with the closing call deactivated:</p> 3264<ol> 3265 <li>First define a new I/O output allocator where the output don't close 3266 the file: 3267 <pre>xmlOutputBufferPtr 3268xmlOutputBufferCreateOwn(FILE *file, xmlCharEncodingHandlerPtr encoder) { 3269����xmlOutputBufferPtr ret; 3270���� 3271����if (xmlOutputCallbackInitialized == 0) 3272��������xmlRegisterDefaultOutputCallbacks(); 3273 3274����if (file == NULL) return(NULL); 3275����ret = xmlAllocOutputBuffer(encoder); 3276����if (ret != NULL) { 3277��������ret->context = file; 3278��������ret->writecallback = xmlFileWrite; 3279��������ret->closecallback = NULL; /* No close callback */ 3280����} 3281����return(ret); 3282} </pre> 3283 </li> 3284 <li>And then use it to save the document: 3285 <pre>FILE *f; 3286xmlOutputBufferPtr output; 3287xmlDocPtr doc; 3288int res; 3289 3290f = ... 3291doc = .... 3292 3293output = xmlOutputBufferCreateOwn(f, NULL); 3294res = xmlSaveFileTo(output, doc, NULL); 3295 </pre> 3296 </li> 3297</ol> 3298 3299<h2><a name="Catalog">Catalog support</a></h2> 3300 3301<p>Table of Content:</p> 3302<ol> 3303 <li><a href="General2">General overview</a></li> 3304 <li><a href="#definition">The definition</a></li> 3305 <li><a href="#Simple">Using catalogs</a></li> 3306 <li><a href="#Some">Some examples</a></li> 3307 <li><a href="#reference">How to tune catalog usage</a></li> 3308 <li><a href="#validate">How to debug catalog processing</a></li> 3309 <li><a href="#Declaring">How to create and maintain catalogs</a></li> 3310 <li><a href="#implemento">The implementor corner quick review of the 3311 API</a></li> 3312 <li><a href="#Other">Other resources</a></li> 3313</ol> 3314 3315<h3><a name="General2">General overview</a></h3> 3316 3317<p>What is a catalog? Basically it's a lookup mechanism used when an entity 3318(a file or a remote resource) references another entity. The catalog lookup 3319is inserted between the moment the reference is recognized by the software 3320(XML parser, stylesheet processing, or even images referenced for inclusion 3321in a rendering) and the time where loading that resource is actually 3322started.</p> 3323 3324<p>It is basically used for 3 things:</p> 3325<ul> 3326 <li>mapping from "logical" names, the public identifiers and a more 3327 concrete name usable for download (and URI). For example it can associate 3328 the logical name 3329 <p>"-//OASIS//DTD DocBook XML V4.1.2//EN"</p> 3330 <p>of the DocBook 4.1.2 XML DTD with the actual URL where it can be 3331 downloaded</p> 3332 <p>http://www.oasis-open.org/docbook/xml/4.1.2/docbookx.dtd</p> 3333 </li> 3334 <li>remapping from a given URL to another one, like an HTTP indirection 3335 saying that 3336 <p>"http://www.oasis-open.org/committes/tr.xsl"</p> 3337 <p>should really be looked at</p> 3338 <p>"http://www.oasis-open.org/committes/entity/stylesheets/base/tr.xsl"</p> 3339 </li> 3340 <li>providing a local cache mechanism allowing to load the entities 3341 associated to public identifiers or remote resources, this is a really 3342 important feature for any significant deployment of XML or SGML since it 3343 allows to avoid the aleas and delays associated to fetching remote 3344 resources.</li> 3345</ul> 3346 3347<h3><a name="definition">The definitions</a></h3> 3348 3349<p>Libxml, as of 2.4.3 implements 2 kind of catalogs:</p> 3350<ul> 3351 <li>the older SGML catalogs, the official spec is SGML Open Technical 3352 Resolution TR9401:1997, but is better understood by reading <a 3353 href="http://www.jclark.com/sp/catalog.htm">the SP Catalog page</a> from 3354 James Clark. This is relatively old and not the preferred mode of 3355 operation of libxml.</li> 3356 <li><a href="http://www.oasis-open.org/committees/entity/spec.html">XML 3357 Catalogs</a> is far more flexible, more recent, uses an XML syntax and 3358 should scale quite better. This is the default option of libxml.</li> 3359</ul> 3360 3361<p></p> 3362 3363<h3><a name="Simple">Using catalog</a></h3> 3364 3365<p>In a normal environment libxml2 will by default check the presence of a 3366catalog in /etc/xml/catalog, and assuming it has been correctly populated, 3367the processing is completely transparent to the document user. To take a 3368concrete example, suppose you are authoring a DocBook document, this one 3369starts with the following DOCTYPE definition:</p> 3370<pre><?xml version='1.0'?> 3371<!DOCTYPE book PUBLIC "-//Norman Walsh//DTD DocBk XML V3.1.4//EN" 3372 "http://nwalsh.com/docbook/xml/3.1.4/db3xml.dtd"></pre> 3373 3374<p>When validating the document with libxml, the catalog will be 3375automatically consulted to lookup the public identifier "-//Norman Walsh//DTD 3376DocBk XML V3.1.4//EN" and the system identifier 3377"http://nwalsh.com/docbook/xml/3.1.4/db3xml.dtd", and if these entities have 3378been installed on your system and the catalogs actually point to them, libxml 3379will fetch them from the local disk.</p> 3380 3381<p style="font-size: 10pt"><strong>Note</strong>: Really don't use this 3382DOCTYPE example it's a really old version, but is fine as an example.</p> 3383 3384<p>Libxml2 will check the catalog each time that it is requested to load an 3385entity, this includes DTD, external parsed entities, stylesheets, etc ... If 3386your system is correctly configured all the authoring phase and processing 3387should use only local files, even if your document stays portable because it 3388uses the canonical public and system ID, referencing the remote document.</p> 3389 3390<h3><a name="Some">Some examples:</a></h3> 3391 3392<p>Here is a couple of fragments from XML Catalogs used in libxml2 early 3393regression tests in <code>test/catalogs</code> :</p> 3394<pre><?xml version="1.0"?> 3395<!DOCTYPE catalog PUBLIC 3396 "-//OASIS//DTD Entity Resolution XML Catalog V1.0//EN" 3397 "http://www.oasis-open.org/committees/entity/release/1.0/catalog.dtd"> 3398<catalog xmlns="urn:oasis:names:tc:entity:xmlns:xml:catalog"> 3399 <public publicId="-//OASIS//DTD DocBook XML V4.1.2//EN" 3400 uri="http://www.oasis-open.org/docbook/xml/4.1.2/docbookx.dtd"/> 3401...</pre> 3402 3403<p>This is the beginning of a catalog for DocBook 4.1.2, XML Catalogs are 3404written in XML, there is a specific namespace for catalog elements 3405"urn:oasis:names:tc:entity:xmlns:xml:catalog". The first entry in this 3406catalog is a <code>public</code> mapping it allows to associate a Public 3407Identifier with an URI.</p> 3408<pre>... 3409 <rewriteSystem systemIdStartString="http://www.oasis-open.org/docbook/" 3410 rewritePrefix="file:///usr/share/xml/docbook/"/> 3411...</pre> 3412 3413<p>A <code>rewriteSystem</code> is a very powerful instruction, it says that 3414any URI starting with a given prefix should be looked at another URI 3415constructed by replacing the prefix with an new one. In effect this acts like 3416a cache system for a full area of the Web. In practice it is extremely useful 3417with a file prefix if you have installed a copy of those resources on your 3418local system.</p> 3419<pre>... 3420<delegatePublic publicIdStartString="-//OASIS//DTD XML Catalog //" 3421 catalog="file:///usr/share/xml/docbook.xml"/> 3422<delegatePublic publicIdStartString="-//OASIS//ENTITIES DocBook XML" 3423 catalog="file:///usr/share/xml/docbook.xml"/> 3424<delegatePublic publicIdStartString="-//OASIS//DTD DocBook XML" 3425 catalog="file:///usr/share/xml/docbook.xml"/> 3426<delegateSystem systemIdStartString="http://www.oasis-open.org/docbook/" 3427 catalog="file:///usr/share/xml/docbook.xml"/> 3428<delegateURI uriStartString="http://www.oasis-open.org/docbook/" 3429 catalog="file:///usr/share/xml/docbook.xml"/> 3430...</pre> 3431 3432<p>Delegation is the core features which allows to build a tree of catalogs, 3433easier to maintain than a single catalog, based on Public Identifier, System 3434Identifier or URI prefixes it instructs the catalog software to look up 3435entries in another resource. This feature allow to build hierarchies of 3436catalogs, the set of entries presented should be sufficient to redirect the 3437resolution of all DocBook references to the specific catalog in 3438<code>/usr/share/xml/docbook.xml</code> this one in turn could delegate all 3439references for DocBook 4.2.1 to a specific catalog installed at the same time 3440as the DocBook resources on the local machine.</p> 3441 3442<h3><a name="reference">How to tune catalog usage:</a></h3> 3443 3444<p>The user can change the default catalog behaviour by redirecting queries 3445to its own set of catalogs, this can be done by setting the 3446<code>XML_CATALOG_FILES</code> environment variable to a list of catalogs, an 3447empty one should deactivate loading the default <code>/etc/xml/catalog</code> 3448default catalog</p> 3449 3450<h3><a name="validate">How to debug catalog processing:</a></h3> 3451 3452<p>Setting up the <code>XML_DEBUG_CATALOG</code> environment variable will 3453make libxml2 output debugging informations for each catalog operations, for 3454example:</p> 3455<pre>orchis:~/XML -> xmllint --memory --noout test/ent2 3456warning: failed to load external entity "title.xml" 3457orchis:~/XML -> export XML_DEBUG_CATALOG= 3458orchis:~/XML -> xmllint --memory --noout test/ent2 3459Failed to parse catalog /etc/xml/catalog 3460Failed to parse catalog /etc/xml/catalog 3461warning: failed to load external entity "title.xml" 3462Catalogs cleanup 3463orchis:~/XML -> </pre> 3464 3465<p>The test/ent2 references an entity, running the parser from memory makes 3466the base URI unavailable and the the "title.xml" entity cannot be loaded. 3467Setting up the debug environment variable allows to detect that an attempt is 3468made to load the <code>/etc/xml/catalog</code> but since it's not present the 3469resolution fails.</p> 3470 3471<p>But the most advanced way to debug XML catalog processing is to use the 3472<strong>xmlcatalog</strong> command shipped with libxml2, it allows to load 3473catalogs and make resolution queries to see what is going on. This is also 3474used for the regression tests:</p> 3475<pre>orchis:~/XML -> /xmlcatalog test/catalogs/docbook.xml \ 3476 "-//OASIS//DTD DocBook XML V4.1.2//EN" 3477http://www.oasis-open.org/docbook/xml/4.1.2/docbookx.dtd 3478orchis:~/XML -> </pre> 3479 3480<p>For debugging what is going on, adding one -v flags increase the verbosity 3481level to indicate the processing done (adding a second flag also indicate 3482what elements are recognized at parsing):</p> 3483<pre>orchis:~/XML -> /xmlcatalog -v test/catalogs/docbook.xml \ 3484 "-//OASIS//DTD DocBook XML V4.1.2//EN" 3485Parsing catalog test/catalogs/docbook.xml's content 3486Found public match -//OASIS//DTD DocBook XML V4.1.2//EN 3487http://www.oasis-open.org/docbook/xml/4.1.2/docbookx.dtd 3488Catalogs cleanup 3489orchis:~/XML -> </pre> 3490 3491<p>A shell interface is also available to debug and process multiple queries 3492(and for regression tests):</p> 3493<pre>orchis:~/XML -> /xmlcatalog -shell test/catalogs/docbook.xml \ 3494 "-//OASIS//DTD DocBook XML V4.1.2//EN" 3495> help 3496Commands available: 3497public PublicID: make a PUBLIC identifier lookup 3498system SystemID: make a SYSTEM identifier lookup 3499resolve PublicID SystemID: do a full resolver lookup 3500add 'type' 'orig' 'replace' : add an entry 3501del 'values' : remove values 3502dump: print the current catalog state 3503debug: increase the verbosity level 3504quiet: decrease the verbosity level 3505exit: quit the shell 3506> public "-//OASIS//DTD DocBook XML V4.1.2//EN" 3507http://www.oasis-open.org/docbook/xml/4.1.2/docbookx.dtd 3508> quit 3509orchis:~/XML -> </pre> 3510 3511<p>This should be sufficient for most debugging purpose, this was actually 3512used heavily to debug the XML Catalog implementation itself.</p> 3513 3514<h3><a name="Declaring">How to create and maintain</a> catalogs:</h3> 3515 3516<p>Basically XML Catalogs are XML files, you can either use XML tools to 3517manage them or use <strong>xmlcatalog</strong> for this. The basic step is 3518to create a catalog the -create option provide this facility:</p> 3519<pre>orchis:~/XML -> /xmlcatalog --create tst.xml 3520<?xml version="1.0"?> 3521<!DOCTYPE catalog PUBLIC "-//OASIS//DTD Entity Resolution XML Catalog V1.0//EN" 3522 "http://www.oasis-open.org/committees/entity/release/1.0/catalog.dtd"> 3523<catalog xmlns="urn:oasis:names:tc:entity:xmlns:xml:catalog"/> 3524orchis:~/XML -> </pre> 3525 3526<p>By default xmlcatalog does not overwrite the original catalog and save the 3527result on the standard output, this can be overridden using the -noout 3528option. The <code>-add</code> command allows to add entries in the 3529catalog:</p> 3530<pre>orchis:~/XML -> /xmlcatalog --noout --create --add "public" \ 3531 "-//OASIS//DTD DocBook XML V4.1.2//EN" \ 3532 http://www.oasis-open.org/docbook/xml/4.1.2/docbookx.dtd tst.xml 3533orchis:~/XML -> cat tst.xml 3534<?xml version="1.0"?> 3535<!DOCTYPE catalog PUBLIC "-//OASIS//DTD Entity Resolution XML Catalog V1.0//EN" \ 3536 "http://www.oasis-open.org/committees/entity/release/1.0/catalog.dtd"> 3537<catalog xmlns="urn:oasis:names:tc:entity:xmlns:xml:catalog"> 3538<public publicId="-//OASIS//DTD DocBook XML V4.1.2//EN" 3539 uri="http://www.oasis-open.org/docbook/xml/4.1.2/docbookx.dtd"/> 3540</catalog> 3541orchis:~/XML -> </pre> 3542 3543<p>The <code>-add</code> option will always take 3 parameters even if some of 3544the XML Catalog constructs (like nextCatalog) will have only a single 3545argument, just pass a third empty string, it will be ignored.</p> 3546 3547<p>Similarly the <code>-del</code> option remove matching entries from the 3548catalog:</p> 3549<pre>orchis:~/XML -> /xmlcatalog --del \ 3550 "http://www.oasis-open.org/docbook/xml/4.1.2/docbookx.dtd" tst.xml 3551<?xml version="1.0"?> 3552<!DOCTYPE catalog PUBLIC "-//OASIS//DTD Entity Resolution XML Catalog V1.0//EN" 3553 "http://www.oasis-open.org/committees/entity/release/1.0/catalog.dtd"> 3554<catalog xmlns="urn:oasis:names:tc:entity:xmlns:xml:catalog"/> 3555orchis:~/XML -> </pre> 3556 3557<p>The catalog is now empty. Note that the matching of <code>-del</code> is 3558exact and would have worked in a similar fashion with the Public ID 3559string.</p> 3560 3561<p>This is rudimentary but should be sufficient to manage a not too complex 3562catalog tree of resources.</p> 3563 3564<h3><a name="implemento">The implementor corner quick review of the 3565API:</a></h3> 3566 3567<p>First, and like for every other module of libxml, there is an 3568automatically generated <a href="html/libxml-catalog.html">API page for 3569catalog support</a>.</p> 3570 3571<p>The header for the catalog interfaces should be included as:</p> 3572<pre>#include <libxml/catalog.h></pre> 3573 3574<p>The API is voluntarily kept very simple. First it is not obvious that 3575applications really need access to it since it is the default behaviour of 3576libxml2 (Note: it is possible to completely override libxml2 default catalog 3577by using <a href="html/libxml-parser.html">xmlSetExternalEntityLoader</a> to 3578plug an application specific resolver).</p> 3579 3580<p>Basically libxml2 support 2 catalog lists:</p> 3581<ul> 3582 <li>the default one, global shared by all the application</li> 3583 <li>a per-document catalog, this one is built if the document uses the 3584 <code>oasis-xml-catalog</code> PIs to specify its own catalog list, it is 3585 associated to the parser context and destroyed when the parsing context 3586 is destroyed.</li> 3587</ul> 3588 3589<p>the document one will be used first if it exists.</p> 3590 3591<h4>Initialization routines:</h4> 3592 3593<p>xmlInitializeCatalog(), xmlLoadCatalog() and xmlLoadCatalogs() should be 3594used at startup to initialize the catalog, if the catalog should be 3595initialized with specific values xmlLoadCatalog() or xmlLoadCatalogs() 3596should be called before xmlInitializeCatalog() which would otherwise do a 3597default initialization first.</p> 3598 3599<p>The xmlCatalogAddLocal() call is used by the parser to grow the document 3600own catalog list if needed.</p> 3601 3602<h4>Preferences setup:</h4> 3603 3604<p>The XML Catalog spec requires the possibility to select default 3605preferences between public and system delegation, 3606xmlCatalogSetDefaultPrefer() allows this, xmlCatalogSetDefaults() and 3607xmlCatalogGetDefaults() allow to control if XML Catalogs resolution should 3608be forbidden, allowed for global catalog, for document catalog or both, the 3609default is to allow both.</p> 3610 3611<p>And of course xmlCatalogSetDebug() allows to generate debug messages 3612(through the xmlGenericError() mechanism).</p> 3613 3614<h4>Querying routines:</h4> 3615 3616<p>xmlCatalogResolve(), xmlCatalogResolveSystem(), xmlCatalogResolvePublic() 3617and xmlCatalogResolveURI() are relatively explicit if you read the XML 3618Catalog specification they correspond to section 7 algorithms, they should 3619also work if you have loaded an SGML catalog with a simplified semantic.</p> 3620 3621<p>xmlCatalogLocalResolve() and xmlCatalogLocalResolveURI() are the same but 3622operate on the document catalog list</p> 3623 3624<h4>Cleanup and Miscellaneous:</h4> 3625 3626<p>xmlCatalogCleanup() free-up the global catalog, xmlCatalogFreeLocal() is 3627the per-document equivalent.</p> 3628 3629<p>xmlCatalogAdd() and xmlCatalogRemove() are used to dynamically modify the 3630first catalog in the global list, and xmlCatalogDump() allows to dump a 3631catalog state, those routines are primarily designed for xmlcatalog, I'm not 3632sure that exposing more complex interfaces (like navigation ones) would be 3633really useful.</p> 3634 3635<p>The xmlParseCatalogFile() is a function used to load XML Catalog files, 3636it's similar as xmlParseFile() except it bypass all catalog lookups, it's 3637provided because this functionality may be useful for client tools.</p> 3638 3639<h4>threaded environments:</h4> 3640 3641<p>Since the catalog tree is built progressively, some care has been taken to 3642try to avoid troubles in multithreaded environments. The code is now thread 3643safe assuming that the libxml2 library has been compiled with threads 3644support.</p> 3645 3646<p></p> 3647 3648<h3><a name="Other">Other resources</a></h3> 3649 3650<p>The XML Catalog specification is relatively recent so there isn't much 3651literature to point at:</p> 3652<ul> 3653 <li>You can find a good rant from Norm Walsh about <a 3654 href="http://www.arbortext.com/Think_Tank/XML_Resources/Issue_Three/issue_three.html">the 3655 need for catalogs</a>, it provides a lot of context informations even if 3656 I don't agree with everything presented. Norm also wrote a more recent 3657 article <a 3658 href="http://wwws.sun.com/software/xml/developers/resolver/article/">XML 3659 entities and URI resolvers</a> describing them.</li> 3660 <li>An <a href="http://home.ccil.org/~cowan/XML/XCatalog.html">old XML 3661 catalog proposal</a> from John Cowan</li> 3662 <li>The <a href="http://www.rddl.org/">Resource Directory Description 3663 Language</a> (RDDL) another catalog system but more oriented toward 3664 providing metadata for XML namespaces.</li> 3665 <li>the page from the OASIS Technical <a 3666 href="http://www.oasis-open.org/committees/entity/">Committee on Entity 3667 Resolution</a> who maintains XML Catalog, you will find pointers to the 3668 specification update, some background and pointers to others tools 3669 providing XML Catalog support</li> 3670 <li>There is a <a href="buildDocBookCatalog">shell script</a> to generate 3671 XML Catalogs for DocBook 4.1.2 . If it can write to the /etc/xml/ 3672 directory, it will set-up /etc/xml/catalog and /etc/xml/docbook based on 3673 the resources found on the system. Otherwise it will just create 3674 ~/xmlcatalog and ~/dbkxmlcatalog and doing: 3675 <p><code>export XML_CATALOG_FILES=$HOME/xmlcatalog</code></p> 3676 <p>should allow to process DocBook documentations without requiring 3677 network accesses for the DTD or stylesheets</p> 3678 </li> 3679 <li>I have uploaded <a href="ftp://xmlsoft.org/test/dbk412catalog.tar.gz">a 3680 small tarball</a> containing XML Catalogs for DocBook 4.1.2 which seems 3681 to work fine for me too</li> 3682 <li>The <a href="http://www.xmlsoft.org/xmlcatalog_man.html">xmlcatalog 3683 manual page</a></li> 3684</ul> 3685 3686<p>If you have suggestions for corrections or additions, simply contact 3687me:</p> 3688 3689<h2><a name="library">The parser interfaces</a></h2> 3690 3691<p>This section is directly intended to help programmers getting bootstrapped 3692using the XML tollkit from the C language. It is not intended to be 3693extensive. I hope the automatically generated documents will provide the 3694completeness required, but as a separate set of documents. The interfaces of 3695the XML parser are by principle low level, Those interested in a higher level 3696API should <a href="#DOM">look at DOM</a>.</p> 3697 3698<p>The <a href="html/libxml-parser.html">parser interfaces for XML</a> are 3699separated from the <a href="html/libxml-htmlparser.html">HTML parser 3700interfaces</a>. Let's have a look at how the XML parser can be called:</p> 3701 3702<h3><a name="Invoking">Invoking the parser : the pull method</a></h3> 3703 3704<p>Usually, the first thing to do is to read an XML input. The parser accepts 3705documents either from in-memory strings or from files. The functions are 3706defined in "parser.h":</p> 3707<dl> 3708 <dt><code>xmlDocPtr xmlParseMemory(char *buffer, int size);</code></dt> 3709 <dd><p>Parse a null-terminated string containing the document.</p> 3710 </dd> 3711</dl> 3712<dl> 3713 <dt><code>xmlDocPtr xmlParseFile(const char *filename);</code></dt> 3714 <dd><p>Parse an XML document contained in a (possibly compressed) 3715 file.</p> 3716 </dd> 3717</dl> 3718 3719<p>The parser returns a pointer to the document structure (or NULL in case of 3720failure).</p> 3721 3722<h3 id="Invoking1">Invoking the parser: the push method</h3> 3723 3724<p>In order for the application to keep the control when the document is 3725being fetched (which is common for GUI based programs) libxml2 provides a 3726push interface, too, as of version 1.8.3. Here are the interface 3727functions:</p> 3728<pre>xmlParserCtxtPtr xmlCreatePushParserCtxt(xmlSAXHandlerPtr sax, 3729 void *user_data, 3730 const char *chunk, 3731 int size, 3732 const char *filename); 3733int xmlParseChunk (xmlParserCtxtPtr ctxt, 3734 const char *chunk, 3735 int size, 3736 int terminate);</pre> 3737 3738<p>and here is a simple example showing how to use the interface:</p> 3739<pre> FILE *f; 3740 3741 f = fopen(filename, "r"); 3742 if (f != NULL) { 3743 int res, size = 1024; 3744 char chars[1024]; 3745 xmlParserCtxtPtr ctxt; 3746 3747 res = fread(chars, 1, 4, f); 3748 if (res > 0) { 3749 ctxt = xmlCreatePushParserCtxt(NULL, NULL, 3750 chars, res, filename); 3751 while ((res = fread(chars, 1, size, f)) > 0) { 3752 xmlParseChunk(ctxt, chars, res, 0); 3753 } 3754 xmlParseChunk(ctxt, chars, 0, 1); 3755 doc = ctxt->myDoc; 3756 xmlFreeParserCtxt(ctxt); 3757 } 3758 }</pre> 3759 3760<p>The HTML parser embedded into libxml2 also has a push interface; the 3761functions are just prefixed by "html" rather than "xml".</p> 3762 3763<h3 id="Invoking2">Invoking the parser: the SAX interface</h3> 3764 3765<p>The tree-building interface makes the parser memory-hungry, first loading 3766the document in memory and then building the tree itself. Reading a document 3767without building the tree is possible using the SAX interfaces (see SAX.h and 3768<a href="http://www.daa.com.au/~james/gnome/xml-sax/xml-sax.html">James 3769Henstridge's documentation</a>). Note also that the push interface can be 3770limited to SAX: just use the two first arguments of 3771<code>xmlCreatePushParserCtxt()</code>.</p> 3772 3773<h3><a name="Building">Building a tree from scratch</a></h3> 3774 3775<p>The other way to get an XML tree in memory is by building it. Basically 3776there is a set of functions dedicated to building new elements. (These are 3777also described in <libxml/tree.h>.) For example, here is a piece of 3778code that produces the XML document used in the previous examples:</p> 3779<pre> #include <libxml/tree.h> 3780 xmlDocPtr doc; 3781 xmlNodePtr tree, subtree; 3782 3783 doc = xmlNewDoc("1.0"); 3784 doc->children = xmlNewDocNode(doc, NULL, "EXAMPLE", NULL); 3785 xmlSetProp(doc->children, "prop1", "gnome is great"); 3786 xmlSetProp(doc->children, "prop2", "& linux too"); 3787 tree = xmlNewChild(doc->children, NULL, "head", NULL); 3788 subtree = xmlNewChild(tree, NULL, "title", "Welcome to Gnome"); 3789 tree = xmlNewChild(doc->children, NULL, "chapter", NULL); 3790 subtree = xmlNewChild(tree, NULL, "title", "The Linux adventure"); 3791 subtree = xmlNewChild(tree, NULL, "p", "bla bla bla ..."); 3792 subtree = xmlNewChild(tree, NULL, "image", NULL); 3793 xmlSetProp(subtree, "href", "linus.gif");</pre> 3794 3795<p>Not really rocket science ...</p> 3796 3797<h3><a name="Traversing">Traversing the tree</a></h3> 3798 3799<p>Basically by <a href="html/libxml-tree.html">including "tree.h"</a> your 3800code has access to the internal structure of all the elements of the tree. 3801The names should be somewhat simple like <strong>parent</strong>, 3802<strong>children</strong>, <strong>next</strong>, <strong>prev</strong>, 3803<strong>properties</strong>, etc... For example, still with the previous 3804example:</p> 3805<pre><code>doc->children->children->children</code></pre> 3806 3807<p>points to the title element,</p> 3808<pre>doc->children->children->next->children->children</pre> 3809 3810<p>points to the text node containing the chapter title "The Linux 3811adventure".</p> 3812 3813<p><strong>NOTE</strong>: XML allows <em>PI</em>s and <em>comments</em> to be 3814present before the document root, so <code>doc->children</code> may point 3815to an element which is not the document Root Element; a function 3816<code>xmlDocGetRootElement()</code> was added for this purpose.</p> 3817 3818<h3><a name="Modifying">Modifying the tree</a></h3> 3819 3820<p>Functions are provided for reading and writing the document content. Here 3821is an excerpt from the <a href="html/libxml-tree.html">tree API</a>:</p> 3822<dl> 3823 <dt><code>xmlAttrPtr xmlSetProp(xmlNodePtr node, const xmlChar *name, const 3824 xmlChar *value);</code></dt> 3825 <dd><p>This sets (or changes) an attribute carried by an ELEMENT node. 3826 The value can be NULL.</p> 3827 </dd> 3828</dl> 3829<dl> 3830 <dt><code>const xmlChar *xmlGetProp(xmlNodePtr node, const xmlChar 3831 *name);</code></dt> 3832 <dd><p>This function returns a pointer to new copy of the property 3833 content. Note that the user must deallocate the result.</p> 3834 </dd> 3835</dl> 3836 3837<p>Two functions are provided for reading and writing the text associated 3838with elements:</p> 3839<dl> 3840 <dt><code>xmlNodePtr xmlStringGetNodeList(xmlDocPtr doc, const xmlChar 3841 *value);</code></dt> 3842 <dd><p>This function takes an "external" string and converts it to one 3843 text node or possibly to a list of entity and text nodes. All 3844 non-predefined entity references like &Gnome; will be stored 3845 internally as entity nodes, hence the result of the function may not be 3846 a single node.</p> 3847 </dd> 3848</dl> 3849<dl> 3850 <dt><code>xmlChar *xmlNodeListGetString(xmlDocPtr doc, xmlNodePtr list, int 3851 inLine);</code></dt> 3852 <dd><p>This function is the inverse of 3853 <code>xmlStringGetNodeList()</code>. It generates a new string 3854 containing the content of the text and entity nodes. Note the extra 3855 argument inLine. If this argument is set to 1, the function will expand 3856 entity references. For example, instead of returning the &Gnome; 3857 XML encoding in the string, it will substitute it with its value (say, 3858 "GNU Network Object Model Environment").</p> 3859 </dd> 3860</dl> 3861 3862<h3><a name="Saving">Saving a tree</a></h3> 3863 3864<p>Basically 3 options are possible:</p> 3865<dl> 3866 <dt><code>void xmlDocDumpMemory(xmlDocPtr cur, xmlChar**mem, int 3867 *size);</code></dt> 3868 <dd><p>Returns a buffer into which the document has been saved.</p> 3869 </dd> 3870</dl> 3871<dl> 3872 <dt><code>extern void xmlDocDump(FILE *f, xmlDocPtr doc);</code></dt> 3873 <dd><p>Dumps a document to an open file descriptor.</p> 3874 </dd> 3875</dl> 3876<dl> 3877 <dt><code>int xmlSaveFile(const char *filename, xmlDocPtr cur);</code></dt> 3878 <dd><p>Saves the document to a file. In this case, the compression 3879 interface is triggered if it has been turned on.</p> 3880 </dd> 3881</dl> 3882 3883<h3><a name="Compressio">Compression</a></h3> 3884 3885<p>The library transparently handles compression when doing file-based 3886accesses. The level of compression on saves can be turned on either globally 3887or individually for one file:</p> 3888<dl> 3889 <dt><code>int xmlGetDocCompressMode (xmlDocPtr doc);</code></dt> 3890 <dd><p>Gets the document compression ratio (0-9).</p> 3891 </dd> 3892</dl> 3893<dl> 3894 <dt><code>void xmlSetDocCompressMode (xmlDocPtr doc, int mode);</code></dt> 3895 <dd><p>Sets the document compression ratio.</p> 3896 </dd> 3897</dl> 3898<dl> 3899 <dt><code>int xmlGetCompressMode(void);</code></dt> 3900 <dd><p>Gets the default compression ratio.</p> 3901 </dd> 3902</dl> 3903<dl> 3904 <dt><code>void xmlSetCompressMode(int mode);</code></dt> 3905 <dd><p>Sets the default compression ratio.</p> 3906 </dd> 3907</dl> 3908 3909<h2><a name="Entities">Entities or no entities</a></h2> 3910 3911<p>Entities in principle are similar to simple C macros. An entity defines an 3912abbreviation for a given string that you can reuse many times throughout the 3913content of your document. Entities are especially useful when a given string 3914may occur frequently within a document, or to confine the change needed to a 3915document to a restricted area in the internal subset of the document (at the 3916beginning). Example:</p> 3917<pre>1 <?xml version="1.0"?> 39182 <!DOCTYPE EXAMPLE SYSTEM "example.dtd" [ 39193 <!ENTITY xml "Extensible Markup Language"> 39204 ]> 39215 <EXAMPLE> 39226 &xml; 39237 </EXAMPLE></pre> 3924 3925<p>Line 3 declares the xml entity. Line 6 uses the xml entity, by prefixing 3926its name with '&' and following it by ';' without any spaces added. There 3927are 5 predefined entities in libxml2 allowing you to escape characters with 3928predefined meaning in some parts of the xml document content: 3929<strong>&lt;</strong> for the character '<', <strong>&gt;</strong> 3930for the character '>', <strong>&apos;</strong> for the character ''', 3931<strong>&quot;</strong> for the character '"', and 3932<strong>&amp;</strong> for the character '&'.</p> 3933 3934<p>One of the problems related to entities is that you may want the parser to 3935substitute an entity's content so that you can see the replacement text in 3936your application. Or you may prefer to keep entity references as such in the 3937content to be able to save the document back without losing this usually 3938precious information (if the user went through the pain of explicitly 3939defining entities, he may have a a rather negative attitude if you blindly 3940substitute them as saving time). The <a 3941href="html/libxml-parser.html#xmlSubstituteEntitiesDefault">xmlSubstituteEntitiesDefault()</a> 3942function allows you to check and change the behaviour, which is to not 3943substitute entities by default.</p> 3944 3945<p>Here is the DOM tree built by libxml2 for the previous document in the 3946default case:</p> 3947<pre>/gnome/src/gnome-xml -> /xmllint --debug test/ent1 3948DOCUMENT 3949version=1.0 3950 ELEMENT EXAMPLE 3951 TEXT 3952 content= 3953 ENTITY_REF 3954 INTERNAL_GENERAL_ENTITY xml 3955 content=Extensible Markup Language 3956 TEXT 3957 content=</pre> 3958 3959<p>And here is the result when substituting entities:</p> 3960<pre>/gnome/src/gnome-xml -> /tester --debug --noent test/ent1 3961DOCUMENT 3962version=1.0 3963 ELEMENT EXAMPLE 3964 TEXT 3965 content= Extensible Markup Language</pre> 3966 3967<p>So, entities or no entities? Basically, it depends on your use case. I 3968suggest that you keep the non-substituting default behaviour and avoid using 3969entities in your XML document or data if you are not willing to handle the 3970entity references elements in the DOM tree.</p> 3971 3972<p>Note that at save time libxml2 enforces the conversion of the predefined 3973entities where necessary to prevent well-formedness problems, and will also 3974transparently replace those with chars (i.e. it will not generate entity 3975reference elements in the DOM tree or call the reference() SAX callback when 3976finding them in the input).</p> 3977 3978<p><span style="background-color: #FF0000">WARNING</span>: handling entities 3979on top of the libxml2 SAX interface is difficult!!! If you plan to use 3980non-predefined entities in your documents, then the learning curve to handle 3981then using the SAX API may be long. If you plan to use complex documents, I 3982strongly suggest you consider using the DOM interface instead and let libxml 3983deal with the complexity rather than trying to do it yourself.</p> 3984 3985<h2><a name="Namespaces">Namespaces</a></h2> 3986 3987<p>The libxml2 library implements <a 3988href="http://www.w3.org/TR/REC-xml-names/">XML namespaces</a> support by 3989recognizing namespace constructs in the input, and does namespace lookup 3990automatically when building the DOM tree. A namespace declaration is 3991associated with an in-memory structure and all elements or attributes within 3992that namespace point to it. Hence testing the namespace is a simple and fast 3993equality operation at the user level.</p> 3994 3995<p>I suggest that people using libxml2 use a namespace, and declare it in the 3996root element of their document as the default namespace. Then they don't need 3997to use the prefix in the content but we will have a basis for future semantic 3998refinement and merging of data from different sources. This doesn't increase 3999the size of the XML output significantly, but significantly increases its 4000value in the long-term. Example:</p> 4001<pre><mydoc xmlns="http://mydoc.example.org/schemas/"> 4002 <elem1>...</elem1> 4003 <elem2>...</elem2> 4004</mydoc></pre> 4005 4006<p>The namespace value has to be an absolute URL, but the URL doesn't have to 4007point to any existing resource on the Web. It will bind all the element and 4008attributes with that URL. I suggest to use an URL within a domain you 4009control, and that the URL should contain some kind of version information if 4010possible. For example, <code>"http://www.gnome.org/gnumeric/1.0/"</code> is a 4011good namespace scheme.</p> 4012 4013<p>Then when you load a file, make sure that a namespace carrying the 4014version-independent prefix is installed on the root element of your document, 4015and if the version information don't match something you know, warn the user 4016and be liberal in what you accept as the input. Also do *not* try to base 4017namespace checking on the prefix value. <foo:text> may be exactly the 4018same as <bar:text> in another document. What really matters is the URI 4019associated with the element or the attribute, not the prefix string (which is 4020just a shortcut for the full URI). In libxml, element and attributes have an 4021<code>ns</code> field pointing to an xmlNs structure detailing the namespace 4022prefix and its URI.</p> 4023 4024<p>@@Interfaces@@</p> 4025<pre>xmlNodePtr node; 4026if(!strncmp(node->name,"mytag",5) 4027 && node->ns 4028 && !strcmp(node->ns->href,"http://www.mysite.com/myns/1.0")) { 4029 ... 4030}</pre> 4031 4032<p>Usually people object to using namespaces together with validity checking. 4033I will try to make sure that using namespaces won't break validity checking, 4034so even if you plan to use or currently are using validation I strongly 4035suggest adding namespaces to your document. A default namespace scheme 4036<code>xmlns="http://...."</code> should not break validity even on less 4037flexible parsers. Using namespaces to mix and differentiate content coming 4038from multiple DTDs will certainly break current validation schemes. To check 4039such documents one needs to use schema-validation, which is supported in 4040libxml2 as well. See <a href="http://www.relaxng.org/">relagx-ng</a> and <a 4041href="http://www.w3c.org/XML/Schema">w3c-schema</a>.</p> 4042 4043<h2><a name="Upgrading">Upgrading 1.x code</a></h2> 4044 4045<p>Incompatible changes:</p> 4046 4047<p>Version 2 of libxml2 is the first version introducing serious backward 4048incompatible changes. The main goals were:</p> 4049<ul> 4050 <li>a general cleanup. A number of mistakes inherited from the very early 4051 versions couldn't be changed due to compatibility constraints. Example 4052 the "childs" element in the nodes.</li> 4053 <li>Uniformization of the various nodes, at least for their header and link 4054 parts (doc, parent, children, prev, next), the goal is a simpler 4055 programming model and simplifying the task of the DOM implementors.</li> 4056 <li>better conformances to the XML specification, for example version 1.x 4057 had an heuristic to try to detect ignorable white spaces. As a result the 4058 SAX event generated were ignorableWhitespace() while the spec requires 4059 character() in that case. This also mean that a number of DOM node 4060 containing blank text may populate the DOM tree which were not present 4061 before.</li> 4062</ul> 4063 4064<h3>How to fix libxml-1.x code:</h3> 4065 4066<p>So client code of libxml designed to run with version 1.x may have to be 4067changed to compile against version 2.x of libxml. Here is a list of changes 4068that I have collected, they may not be sufficient, so in case you find other 4069change which are required, <a href="mailto:Daniel.Veillard@w3.org">drop me a 4070mail</a>:</p> 4071<ol> 4072 <li>The package name have changed from libxml to libxml2, the library name 4073 is now -lxml2 . There is a new xml2-config script which should be used to 4074 select the right parameters libxml2</li> 4075 <li>Node <strong>childs</strong> field has been renamed 4076 <strong>children</strong> so s/childs/children/g should be applied 4077 (probability of having "childs" anywhere else is close to 0+</li> 4078 <li>The document don't have anymore a <strong>root</strong> element it has 4079 been replaced by <strong>children</strong> and usually you will get a 4080 list of element here. For example a Dtd element for the internal subset 4081 and it's declaration may be found in that list, as well as processing 4082 instructions or comments found before or after the document root element. 4083 Use <strong>xmlDocGetRootElement(doc)</strong> to get the root element of 4084 a document. Alternatively if you are sure to not reference DTDs nor have 4085 PIs or comments before or after the root element 4086 s/->root/->children/g will probably do it.</li> 4087 <li>The white space issue, this one is more complex, unless special case of 4088 validating parsing, the line breaks and spaces usually used for indenting 4089 and formatting the document content becomes significant. So they are 4090 reported by SAX and if your using the DOM tree, corresponding nodes are 4091 generated. Too approach can be taken: 4092 <ol> 4093 <li>lazy one, use the compatibility call 4094 <strong>xmlKeepBlanksDefault(0)</strong> but be aware that you are 4095 relying on a special (and possibly broken) set of heuristics of 4096 libxml to detect ignorable blanks. Don't complain if it breaks or 4097 make your application not 100% clean w.r.t. to it's input.</li> 4098 <li>the Right Way: change you code to accept possibly insignificant 4099 blanks characters, or have your tree populated with weird blank text 4100 nodes. You can spot them using the commodity function 4101 <strong>xmlIsBlankNode(node)</strong> returning 1 for such blank 4102 nodes.</li> 4103 </ol> 4104 <p>Note also that with the new default the output functions don't add any 4105 extra indentation when saving a tree in order to be able to round trip 4106 (read and save) without inflating the document with extra formatting 4107 chars.</p> 4108 </li> 4109 <li>The include path has changed to $prefix/libxml/ and the includes 4110 themselves uses this new prefix in includes instructions... If you are 4111 using (as expected) the 4112 <pre>xml2-config --cflags</pre> 4113 <p>output to generate you compile commands this will probably work out of 4114 the box</p> 4115 </li> 4116 <li>xmlDetectCharEncoding takes an extra argument indicating the length in 4117 byte of the head of the document available for character detection.</li> 4118</ol> 4119 4120<h3>Ensuring both libxml-1.x and libxml-2.x compatibility</h3> 4121 4122<p>Two new version of libxml (1.8.11) and libxml2 (2.3.4) have been released 4123to allow smooth upgrade of existing libxml v1code while retaining 4124compatibility. They offers the following:</p> 4125<ol> 4126 <li>similar include naming, one should use 4127 <strong>#include<libxml/...></strong> in both cases.</li> 4128 <li>similar identifiers defined via macros for the child and root fields: 4129 respectively <strong>xmlChildrenNode</strong> and 4130 <strong>xmlRootNode</strong></li> 4131 <li>a new macro <strong>LIBXML_TEST_VERSION</strong> which should be 4132 inserted once in the client code</li> 4133</ol> 4134 4135<p>So the roadmap to upgrade your existing libxml applications is the 4136following:</p> 4137<ol> 4138 <li>install the libxml-1.8.8 (and libxml-devel-1.8.8) packages</li> 4139 <li>find all occurrences where the xmlDoc <strong>root</strong> field is 4140 used and change it to <strong>xmlRootNode</strong></li> 4141 <li>similarly find all occurrences where the xmlNode 4142 <strong>childs</strong> field is used and change it to 4143 <strong>xmlChildrenNode</strong></li> 4144 <li>add a <strong>LIBXML_TEST_VERSION</strong> macro somewhere in your 4145 <strong>main()</strong> or in the library init entry point</li> 4146 <li>Recompile, check compatibility, it should still work</li> 4147 <li>Change your configure script to look first for xml2-config and fall 4148 back using xml-config . Use the --cflags and --libs output of the command 4149 as the Include and Linking parameters needed to use libxml.</li> 4150 <li>install libxml2-2.3.x and libxml2-devel-2.3.x (libxml-1.8.y and 4151 libxml-devel-1.8.y can be kept simultaneously)</li> 4152 <li>remove your config.cache, relaunch your configuration mechanism, and 4153 recompile, if steps 2 and 3 were done right it should compile as-is</li> 4154 <li>Test that your application is still running correctly, if not this may 4155 be due to extra empty nodes due to formating spaces being kept in libxml2 4156 contrary to libxml1, in that case insert xmlKeepBlanksDefault(1) in your 4157 code before calling the parser (next to 4158 <strong>LIBXML_TEST_VERSION</strong> is a fine place).</li> 4159</ol> 4160 4161<p>Following those steps should work. It worked for some of my own code.</p> 4162 4163<p>Let me put some emphasis on the fact that there is far more changes from 4164libxml 1.x to 2.x than the ones you may have to patch for. The overall code 4165has been considerably cleaned up and the conformance to the XML specification 4166has been drastically improved too. Don't take those changes as an excuse to 4167not upgrade, it may cost a lot on the long term ...</p> 4168 4169<h2><a name="Thread">Thread safety</a></h2> 4170 4171<p>Starting with 2.4.7, libxml2 makes provisions to ensure that concurrent 4172threads can safely work in parallel parsing different documents. There is 4173however a couple of things to do to ensure it:</p> 4174<ul> 4175 <li>configure the library accordingly using the --with-threads options</li> 4176 <li>call xmlInitParser() in the "main" thread before using any of the 4177 libxml2 API (except possibly selecting a different memory allocator)</li> 4178</ul> 4179 4180<p>Note that the thread safety cannot be ensured for multiple threads sharing 4181the same document, the locking must be done at the application level, libxml 4182exports a basic mutex and reentrant mutexes API in <libxml/threads.h>. 4183The parts of the library checked for thread safety are:</p> 4184<ul> 4185 <li>concurrent loading</li> 4186 <li>file access resolution</li> 4187 <li>catalog access</li> 4188 <li>catalog building</li> 4189 <li>entities lookup/accesses</li> 4190 <li>validation</li> 4191 <li>global variables per-thread override</li> 4192 <li>memory handling</li> 4193</ul> 4194 4195<p>XPath is supposed to be thread safe now, but this wasn't tested 4196seriously.</p> 4197 4198<h2><a name="DOM"></a><a name="Principles">DOM Principles</a></h2> 4199 4200<p><a href="http://www.w3.org/DOM/">DOM</a> stands for the <em>Document 4201Object Model</em>; this is an API for accessing XML or HTML structured 4202documents. Native support for DOM in Gnome is on the way (module gnome-dom), 4203and will be based on gnome-xml. This will be a far cleaner interface to 4204manipulate XML files within Gnome since it won't expose the internal 4205structure.</p> 4206 4207<p>The current DOM implementation on top of libxml2 is the <a 4208href="http://cvs.gnome.org/lxr/source/gdome2/">gdome2 Gnome module</a>, this 4209is a full DOM interface, thanks to Paolo Casarini, check the <a 4210href="http://www.cs.unibo.it/~casarini/gdome2/">Gdome2 homepage</a> for more 4211informations.</p> 4212 4213<h2><a name="Example"></a><a name="real">A real example</a></h2> 4214 4215<p>Here is a real size example, where the actual content of the application 4216data is not kept in the DOM tree but uses internal structures. It is based on 4217a proposal to keep a database of jobs related to Gnome, with an XML based 4218storage structure. Here is an <a href="gjobs.xml">XML encoded jobs 4219base</a>:</p> 4220<pre><?xml version="1.0"?> 4221<gjob:Helping xmlns:gjob="http://www.gnome.org/some-location"> 4222 <gjob:Jobs> 4223 4224 <gjob:Job> 4225 <gjob:Project ID="3"/> 4226 <gjob:Application>GBackup</gjob:Application> 4227 <gjob:Category>Development</gjob:Category> 4228 4229 <gjob:Update> 4230 <gjob:Status>Open</gjob:Status> 4231 <gjob:Modified>Mon, 07 Jun 1999 20:27:45 -0400 MET DST</gjob:Modified> 4232 <gjob:Salary>USD 0.00</gjob:Salary> 4233 </gjob:Update> 4234 4235 <gjob:Developers> 4236 <gjob:Developer> 4237 </gjob:Developer> 4238 </gjob:Developers> 4239 4240 <gjob:Contact> 4241 <gjob:Person>Nathan Clemons</gjob:Person> 4242 <gjob:Email>nathan@windsofstorm.net</gjob:Email> 4243 <gjob:Company> 4244 </gjob:Company> 4245 <gjob:Organisation> 4246 </gjob:Organisation> 4247 <gjob:Webpage> 4248 </gjob:Webpage> 4249 <gjob:Snailmail> 4250 </gjob:Snailmail> 4251 <gjob:Phone> 4252 </gjob:Phone> 4253 </gjob:Contact> 4254 4255 <gjob:Requirements> 4256 The program should be released as free software, under the GPL. 4257 </gjob:Requirements> 4258 4259 <gjob:Skills> 4260 </gjob:Skills> 4261 4262 <gjob:Details> 4263 A GNOME based system that will allow a superuser to configure 4264 compressed and uncompressed files and/or file systems to be backed 4265 up with a supported media in the system. This should be able to 4266 perform via find commands generating a list of files that are passed 4267 to tar, dd, cpio, cp, gzip, etc., to be directed to the tape machine 4268 or via operations performed on the filesystem itself. Email 4269 notification and GUI status display very important. 4270 </gjob:Details> 4271 4272 </gjob:Job> 4273 4274 </gjob:Jobs> 4275</gjob:Helping></pre> 4276 4277<p>While loading the XML file into an internal DOM tree is a matter of 4278calling only a couple of functions, browsing the tree to gather the data and 4279generate the internal structures is harder, and more error prone.</p> 4280 4281<p>The suggested principle is to be tolerant with respect to the input 4282structure. For example, the ordering of the attributes is not significant, 4283the XML specification is clear about it. It's also usually a good idea not to 4284depend on the order of the children of a given node, unless it really makes 4285things harder. Here is some code to parse the information for a person:</p> 4286<pre>/* 4287 * A person record 4288 */ 4289typedef struct person { 4290 char *name; 4291 char *email; 4292 char *company; 4293 char *organisation; 4294 char *smail; 4295 char *webPage; 4296 char *phone; 4297} person, *personPtr; 4298 4299/* 4300 * And the code needed to parse it 4301 */ 4302personPtr parsePerson(xmlDocPtr doc, xmlNsPtr ns, xmlNodePtr cur) { 4303 personPtr ret = NULL; 4304 4305DEBUG("parsePerson\n"); 4306 /* 4307 * allocate the struct 4308 */ 4309 ret = (personPtr) malloc(sizeof(person)); 4310 if (ret == NULL) { 4311 fprintf(stderr,"out of memory\n"); 4312 return(NULL); 4313 } 4314 memset(ret, 0, sizeof(person)); 4315 4316 /* We don't care what the top level element name is */ 4317 cur = cur->xmlChildrenNode; 4318 while (cur != NULL) { 4319 if ((!strcmp(cur->name, "Person")) && (cur->ns == ns)) 4320 ret->name = xmlNodeListGetString(doc, cur->xmlChildrenNode, 1); 4321 if ((!strcmp(cur->name, "Email")) && (cur->ns == ns)) 4322 ret->email = xmlNodeListGetString(doc, cur->xmlChildrenNode, 1); 4323 cur = cur->next; 4324 } 4325 4326 return(ret); 4327}</pre> 4328 4329<p>Here are a couple of things to notice:</p> 4330<ul> 4331 <li>Usually a recursive parsing style is the more convenient one: XML data 4332 is by nature subject to repetitive constructs and usually exhibits highly 4333 structured patterns.</li> 4334 <li>The two arguments of type <em>xmlDocPtr</em> and <em>xmlNsPtr</em>, 4335 i.e. the pointer to the global XML document and the namespace reserved to 4336 the application. Document wide information are needed for example to 4337 decode entities and it's a good coding practice to define a namespace for 4338 your application set of data and test that the element and attributes 4339 you're analyzing actually pertains to your application space. This is 4340 done by a simple equality test (cur->ns == ns).</li> 4341 <li>To retrieve text and attributes value, you can use the function 4342 <em>xmlNodeListGetString</em> to gather all the text and entity reference 4343 nodes generated by the DOM output and produce an single text string.</li> 4344</ul> 4345 4346<p>Here is another piece of code used to parse another level of the 4347structure:</p> 4348<pre>#include <libxml/tree.h> 4349/* 4350 * a Description for a Job 4351 */ 4352typedef struct job { 4353 char *projectID; 4354 char *application; 4355 char *category; 4356 personPtr contact; 4357 int nbDevelopers; 4358 personPtr developers[100]; /* using dynamic alloc is left as an exercise */ 4359} job, *jobPtr; 4360 4361/* 4362 * And the code needed to parse it 4363 */ 4364jobPtr parseJob(xmlDocPtr doc, xmlNsPtr ns, xmlNodePtr cur) { 4365 jobPtr ret = NULL; 4366 4367DEBUG("parseJob\n"); 4368 /* 4369 * allocate the struct 4370 */ 4371 ret = (jobPtr) malloc(sizeof(job)); 4372 if (ret == NULL) { 4373 fprintf(stderr,"out of memory\n"); 4374 return(NULL); 4375 } 4376 memset(ret, 0, sizeof(job)); 4377 4378 /* We don't care what the top level element name is */ 4379 cur = cur->xmlChildrenNode; 4380 while (cur != NULL) { 4381 4382 if ((!strcmp(cur->name, "Project")) && (cur->ns == ns)) { 4383 ret->projectID = xmlGetProp(cur, "ID"); 4384 if (ret->projectID == NULL) { 4385 fprintf(stderr, "Project has no ID\n"); 4386 } 4387 } 4388 if ((!strcmp(cur->name, "Application")) && (cur->ns == ns)) 4389 ret->application = xmlNodeListGetString(doc, cur->xmlChildrenNode, 1); 4390 if ((!strcmp(cur->name, "Category")) && (cur->ns == ns)) 4391 ret->category = xmlNodeListGetString(doc, cur->xmlChildrenNode, 1); 4392 if ((!strcmp(cur->name, "Contact")) && (cur->ns == ns)) 4393 ret->contact = parsePerson(doc, ns, cur); 4394 cur = cur->next; 4395 } 4396 4397 return(ret); 4398}</pre> 4399 4400<p>Once you are used to it, writing this kind of code is quite simple, but 4401boring. Ultimately, it could be possible to write stubbers taking either C 4402data structure definitions, a set of XML examples or an XML DTD and produce 4403the code needed to import and export the content between C data and XML 4404storage. This is left as an exercise to the reader :-)</p> 4405 4406<p>Feel free to use <a href="example/gjobread.c">the code for the full C 4407parsing example</a> as a template, it is also available with Makefile in the 4408Gnome CVS base under gnome-xml/example</p> 4409 4410<h2><a name="Contributi">Contributions</a></h2> 4411<ul> 4412 <li>Bjorn Reese, William Brack and Thomas Broyer have provided a number of 4413 patches, Gary Pennington worked on the validation API, threading support 4414 and Solaris port.</li> 4415 <li>John Fleck helps maintaining the documentation and man pages.</li> 4416 <li><a href="mailto:igor@zlatkovic.com">Igor Zlatkovic</a> is now the 4417 maintainer of the Windows port, <a 4418 href="http://www.zlatkovic.com/projects/libxml/index.html">he provides 4419 binaries</a></li> 4420 <li><a href="mailto:Gary.Pennington@sun.com">Gary Pennington</a> provides 4421 <a href="http://garypennington.net/libxml2/">Solaris binaries</a></li> 4422 <li><a 4423 href="http://mail.gnome.org/archives/xml/2001-March/msg00014.html">Matt 4424 Sergeant</a> developed <a 4425 href="http://axkit.org/download/">XML::LibXSLT</a>, a Perl wrapper for 4426 libxml2/libxslt as part of the <a href="http://axkit.com/">AxKit XML 4427 application server</a></li> 4428 <li><a href="mailto:fnatter@gmx.net">Felix Natter</a> and <a 4429 href="mailto:geertk@ai.rug.nl">Geert Kloosterman</a> provide <a 4430 href="libxml-doc.el">an emacs module</a> to lookup libxml(2) functions 4431 documentation</li> 4432 <li><a href="mailto:sherwin@nlm.nih.gov">Ziying Sherwin</a> provided <a 4433 href="http://xmlsoft.org/messages/0488.html">man pages</a></li> 4434 <li>there is a module for <a 4435 href="http://acs-misc.sourceforge.net/nsxml.html">libxml/libxslt support 4436 in OpenNSD/AOLServer</a></li> 4437 <li><a href="mailto:dkuhlman@cutter.rexx.com">Dave Kuhlman</a> provided the 4438 first version of libxml/libxslt <a 4439 href="http://www.rexx.com/~dkuhlman">wrappers for Python</a></li> 4440 <li>Petr Kozelka provides <a 4441 href="http://sourceforge.net/projects/libxml2-pas">Pascal units to glue 4442 libxml2</a> with Kylix and Delphi and other Pascal compilers</li> 4443 <li><a href="mailto:aleksey@aleksey.com">Aleksey Sanin</a> implemented the 4444 <a href="http://www.w3.org/Signature/">XML Canonicalization and XML 4445 Digital Signature</a> <a 4446 href="http://www.aleksey.com/xmlsec/">implementations for libxml2</a></li> 4447 <li><a href="mailto:Steve.Ball@zveno.com">Steve Ball</a>, <a 4448 href="http://www.zveno.com/">Zveno</a> and contributors maintain <a 4449 href="http://tclxml.sourceforge.net/">tcl bindings for libxml2 and 4450 libxslt</a>, as well as <a 4451 href="http://tclxml.sf.net/tkxmllint.html">tkxmllint</a> a GUI for 4452 xmllint and <a href="http://tclxml.sf.net/tkxsltproc.html">tkxsltproc</a> 4453 a GUI for xsltproc.</li> 4454</ul> 4455 4456<p></p> 4457</body> 4458</html> 4459
