xml.html revision d99224d79c2390d671b096f46f8819177efbd0f9
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 (FTP and rsync are 604available), there is also mirrors (<a 605href="ftp://speakeasy.rpmfind.net/pub/libxml/">Seattle</a>, <a 606href="ftp://fr.rpmfind.net/pub/libxml/">France</a>) or on the <a 607href="ftp://ftp.gnome.org/pub/GNOME/MIRRORS.html">Gnome FTP server</a> as <a 608href="ftp://ftp.gnome.org/pub/GNOME/sources/libxml2/2.6/">source archive</a> 609, Antonin Sprinzl also provide <a href="ftp://gd.tuwien.ac.at/pub/libxml/">a 610mirror in Austria</a>. (NOTE that you need both the <a 611href="http://rpmfind.net/linux/RPM/libxml2.html">libxml(2)</a> and <a 612href="http://rpmfind.net/linux/RPM/libxml2-devel.html">libxml(2)-devel</a> 613packages installed to compile applications using libxml.)</p> 614 615<p>Binary ports:</p> 616<ul> 617 <li>Red Hat RPMs for i386 are available directly on <a 618 href="ftp://xmlsoft.org/">xmlsoft.org</a>, the source RPM will compile on 619 any architecture supported by Red Hat.</li> 620 <li><p><a href="mailto:igor@zlatkovic.com">Igor Zlatkovic</a></p> 621 is now the maintainer of the Windows port, <a 622 href="http://www.zlatkovic.com/projects/libxml/index.html">he provides 623 binaries</a>.</li> 624 <li><a href="mailto:Gary.Pennington@sun.com">Gary Pennington</a> provides 625 <a href="http://garypennington.net/libxml2/">Solaris binaries</a>.</li> 626 <li><a href="mailto:Steve.Ball@zveno.com">Steve Ball</a> provides <a 627 href="http://www.zveno.com/open_source/libxml2xslt.html">Mac Os X 628 binaries</a>.</li> 629 <li>The HP-UX porting center provides <a 630 href="http://hpux.connect.org.uk/hppd/hpux/Gnome/">HP-UX binaries</a></li> 631</ul> 632 633<p>If you know other supported binary ports, please <a 634href="http://veillard.com/">contact me</a>.</p> 635 636<p><a name="Snapshot">Snapshot:</a></p> 637<ul> 638 <li>Code from the W3C cvs base gnome-xml <a 639 href="ftp://xmlsoft.org/cvs-snapshot.tar.gz">cvs-snapshot.tar.gz</a>.</li> 640 <li>Docs, content of the web site, the list archive included <a 641 href="ftp://xmlsoft.org/libxml-docs.tar.gz">libxml-docs.tar.gz</a>.</li> 642</ul> 643 644<p><a name="Contribs">Contributions:</a></p> 645 646<p>I do accept external contributions, especially if compiling on another 647platform, get in touch with the list to upload the package, wrappers for 648various languages have been provided, and can be found in the <a 649href="python.html">bindings section</a></p> 650 651<p>Libxml2 is also available from CVS:</p> 652<ul> 653 <li><p>The <a 654 href="http://cvs.gnome.org/bonsai/rview.cgi?cvsroot=/cvs/gnome&dir=gnome-xml">Gnome 655 CVS base</a>. Check the <a 656 href="http://developer.gnome.org/tools/cvs.html">Gnome CVS Tools</a> 657 page; the CVS module is <b>libxml2</b>.</p> 658 </li> 659 <li>The <strong>libxslt</strong> module is also present there</li> 660</ul> 661 662<h2><a name="News">News</a></h2> 663 664<p>Items not finished and worked on, get in touch with the list if you want 665to help those</p> 666<ul> 667 <li>More testing on RelaxNG</li> 668 <li>Finishing up <a href="http://www.w3.org/TR/xmlschema-1/">XML 669 Schemas</a></li> 670</ul> 671 672<p>There is the list of public releases:</p> 673 674<h3>2.6.8: Mar 23 2004</h3> 675<ul> 676 <li>First step of the cleanup of the serialization code and APIs</li> 677 <li>XML Schemas: mixed content (Adam Dickmeiss), QName handling fixes (Adam 678 Dickmeiss), anyURI for "" (John Belmonte)</li> 679 <li>Python: Canonicalization C14N support added (Anthony Carrico)</li> 680 <li>xmlDocCopyNode() extension (William)</li> 681 <li>Relax-NG: fix when processing XInclude results (William), external 682 reference in interleave (William), missing error on <choice> 683 failure (William), memory leak in schemas datatype facets.</li> 684 <li>xmlWriter: patch for better DTD support (Alfred Mickautsch)</li> 685 <li>bug fixes: xmlXPathLangFunction memory leak (Mike Hommey and William 686 Brack), no ID errors if using HTML_PARSE_NOERROR, xmlcatalog fallbacks to 687 URI on SYSTEM lookup failure, XInclude parse flags inheritance (William), 688 XInclude and XPointer fixes for entities (William), XML parser bug 689 reported by Holger Rauch, nanohttp fd leak (William), regexps char 690 groups '-' handling (William), dictionnary reference counting problems, 691 do not close stderr.</li> 692 <li>performance patches from Petr Pajas</li> 693 <li>Documentation fixes: XML_CATALOG_FILES in man pages (Mike Hommey)</li> 694 <li>compilation and portability fixes: --without-valid, catalog cleanups 695 (Peter Breitenlohner), MingW patch (Roland Schwingel), cross-compilation 696 to Windows (Christophe de Vienne), --with-html-dir fixup (Julio Merino 697 Vidal), Windows build (Eric Zurcher)</li> 698</ul> 699 700<h3>2.6.7: Feb 23 2004</h3> 701<ul> 702 <li>documentation: tutorial updates (John Fleck), benchmark results</li> 703 <li>xmlWriter: updates and fixes (Alfred Mickautsch, Lucas Brasilino)</li> 704 <li>XPath optimization (Petr Pajas)</li> 705 <li>DTD ID handling optimization</li> 706 <li>bugfixes: xpath number with > 19 fractional (William Brack), push 707 mode with unescaped '>' characters, fix xmllint --stream --timing, fix 708 xmllint --memory --stream memory usage, xmlAttrSerializeTxtContent 709 handling NULL, trying to fix Relax-NG/Perl interface.</li> 710 <li>python: 2.3 compatibility, whitespace fixes (Malcolm Tredinnick)</li> 711 <li>Added relaxng option to xmllint --shell</li> 712</ul> 713 714<h3>2.6.6: Feb 12 2004</h3> 715<ul> 716 <li>nanohttp and nanoftp: buffer overflow error on URI parsing (Igor and 717 William) reported by Yuuichi Teranishi</li> 718 <li>bugfixes: make test and path issues, xmlWriter attribute serialization 719 (William Brack), xmlWriter indentation (William), schemas validation 720 (Eric Haszlakiewicz), XInclude dictionnaries issues (William and Oleg 721 Paraschenko), XInclude empty fallback (William), HTML warnings (William), 722 XPointer in XInclude (William), Python namespace serialization, 723 isolat1ToUTF8 bound error (Alfred Mickautsch), output of parameter 724 entities in internal subset (William), internal subset bug in push mode, 725 <xs:all> fix (Alexey Sarytchev)</li> 726 <li>Build: fix for automake-1.8 (Alexander Winston), warnings removal 727 (Philip Ludlam), SOCKLEN_T detection fixes (Daniel Richard), fix 728 --with-minimum configuration.</li> 729 <li>XInclude: allow the 2001 namespace without warning.</li> 730 <li>Documentation: missing example/index.html (John Fleck), version 731 dependancies (John Fleck)</li> 732 <li>reader API: structured error reporting (Steve Ball)</li> 733 <li>Windows compilation: mingw, msys (Mikhail Grushinskiy), function 734 prototype (Cameron Johnson), MSVC6 compiler warnings, _WINSOCKAPI_ 735 patch</li> 736 <li>Parsers: added xmlByteConsumed(ctxt) API to get the byte offest in 737 input.</li> 738</ul> 739 740<h3>2.6.5: Jan 25 2004</h3> 741<ul> 742 <li>Bugfixes: dictionnaries for schemas (William Brack), regexp segfault 743 (William), xs:all problem (William), a number of XPointer bugfixes 744 (William), xmllint error go to stderr, DTD validation problem with 745 namespace, memory leak (William), SAX1 cleanup and minimal options fixes 746 (Mark Vadoc), parser context reset on error (Shaun McCance), XPath union 747 evaluation problem (William) , xmlReallocLoc with NULL (Aleksey Sanin), 748 XML Schemas double free (Steve Ball), XInclude with no href, argument 749 callbacks order for XPath callbacks (Frederic Peters)</li> 750 <li>Documentation: python scripts (William Brack), xslt stylesheets (John 751 Fleck), doc (Sven Zimmerman), I/O example.</li> 752 <li>Python bindings: fixes (William), enum support (St�phane Bidoul), 753 structured error reporting (St�phane Bidoul)</li> 754 <li>XInclude: various fixes for conformance, problem related to dictionnary 755 references (William & me), recursion (William)</li> 756 <li>xmlWriter: indentation (Lucas Brasilino), memory leaks (Alfred 757 Mickautsch),</li> 758 <li>xmlSchemas: normalizedString datatype (John Belmonte)</li> 759 <li>code cleanup for strings functions (William)</li> 760 <li>Windows: compiler patches (Mark Vakoc)</li> 761 <li>Parser optimizations, a few new XPath and dictionnary APIs for future 762 XSLT optimizations.</li> 763</ul> 764 765<h3>2.6.4: Dec 24 2003</h3> 766<ul> 767 <li>Windows build fixes (Igor Zlatkovic)</li> 768 <li>Some serious XInclude problems reported by Oleg Paraschenko and</li> 769 <li>Unix and Makefile packaging fixes (me, William Brack,</li> 770 <li>Documentation improvements (John Fleck, William Brack), example fix 771 (Lucas Brasilino)</li> 772 <li>bugfixes: xmlTextReaderExpand() with xmlReaderWalker, XPath handling of 773 NULL strings (William Brack) , API building reader or parser from 774 filedescriptor should not close it, changed XPath sorting to be stable 775 again (William Brack), xmlGetNodePath() generating '(null)' (William 776 Brack), DTD validation and namespace bug (William Brack), XML Schemas 777 double inclusion behaviour</li> 778</ul> 779 780<h3>2.6.3: Dec 10 2003</h3> 781<ul> 782 <li>documentation updates and cleanup (DV, William Brack, John Fleck)</li> 783 <li>added a repository of examples, examples from Aleksey Sanin, Dodji 784 Seketeli, Alfred Mickautsch</li> 785 <li>Windows updates: Mark Vakoc, Igor Zlatkovic, Eric Zurcher, Mingw 786 (Kenneth Haley)</li> 787 <li>Unicode range checking (William Brack)</li> 788 <li>code cleanup (William Brack)</li> 789 <li>Python bindings: doc (John Fleck), bug fixes</li> 790 <li>UTF-16 cleanup and BOM issues (William Brack)</li> 791 <li>bug fixes: ID and xmlReader validation, XPath (William Brack), 792 xmlWriter (Alfred Mickautsch), hash.h inclusion problem, HTML parser 793 (James Bursa), attribute defaulting and validation, some serialization 794 cleanups, XML_GET_LINE macro, memory debug when using threads (William 795 Brack), serialization of attributes and entities content, xmlWriter 796 (Daniel Schulman)</li> 797 <li>XInclude bugfix, new APIs and update to the last version including the 798 namespace change.</li> 799 <li>XML Schemas improvements: include (Robert Stepanek), import and 800 namespace handling, fixed the regression tests troubles, added examples 801 based on Eric van der Vlist book, regexp fixes</li> 802 <li>preliminary pattern support for streaming (needed for schemas 803 constraints), added xmlTextReaderPreservePattern() to collect subdocument 804 when streaming.</li> 805 <li>various fixes in the structured error handling</li> 806</ul> 807 808<h3>2.6.2: Nov 4 2003</h3> 809<ul> 810 <li>XPath context unregistration fixes</li> 811 <li>text node coalescing fixes (Mark Lilback)</li> 812 <li>API to screate a W3C Schemas from an existing document (Steve Ball)</li> 813 <li>BeOS patches (Marcin 'Shard' Konicki)</li> 814 <li>xmlStrVPrintf function added (Aleksey Sanin)</li> 815 <li>compilation fixes (Mark Vakoc)</li> 816 <li>stdin parsing fix (William Brack)</li> 817 <li>a posteriori DTD validation fixes</li> 818 <li>xmlReader bug fixes: Walker fixes, python bindings</li> 819 <li>fixed xmlStopParser() to really stop the parser and errors</li> 820 <li>always generate line numbers when using the new xmlReadxxx 821 functions</li> 822 <li>added XInclude support to the xmlReader interface</li> 823 <li>implemented XML_PARSE_NONET parser option</li> 824 <li>DocBook XSLT processing bug fixed</li> 825 <li>HTML serialization for <p> elements (William Brack and me)</li> 826 <li>XPointer failure in XInclude are now handled as resource errors</li> 827 <li>fixed xmllint --html to use the HTML serializer on output (added 828 --xmlout to implement the previous behaviour of saving it using the XML 829 serializer)</li> 830</ul> 831 832<h3>2.6.1: Oct 28 2003</h3> 833<ul> 834 <li>Mostly bugfixes after the big 2.6.0 changes</li> 835 <li>Unix compilation patches: libxml.m4 (Patrick Welche), warnings cleanup 836 (William Brack)</li> 837 <li>Windows compilation patches (Joachim Bauch, Stephane Bidoul, Igor 838 Zlatkovic)</li> 839 <li>xmlWriter bugfix (Alfred Mickautsch)</li> 840 <li>chvalid.[ch]: couple of fixes from Stephane Bidoul</li> 841 <li>context reset: error state reset, push parser reset (Graham 842 Bennett)</li> 843 <li>context reuse: generate errors if file is not readable</li> 844 <li>defaulted attributes for element coming from internal entities 845 (Stephane Bidoul)</li> 846 <li>Python: tab and spaces mix (William Brack)</li> 847 <li>Error handler could crash in DTD validation in 2.6.0</li> 848 <li>xmlReader: do not use the document or element _private field</li> 849 <li>testSAX.c: avoid a problem with some PIs (Massimo Morara)</li> 850 <li>general bug fixes: mandatory encoding in text decl, serializing 851 Document Fragment nodes, xmlSearchNs 2.6.0 problem (Kasimier Buchcik), 852 XPath errors not reported, slow HTML parsing of large documents.</li> 853</ul> 854 855<h3>2.6.0: Oct 20 2003</h3> 856<ul> 857 <li>Major revision release: should be API and ABI compatible but got a lot 858 of change</li> 859 <li>Increased the library modularity, far more options can be stripped out, 860 a --with-minimum configuration will weight around 160KBytes</li> 861 <li>Use per parser and per document dictionnary, allocate names and small 862 text nodes from the dictionnary</li> 863 <li>Switch to a SAX2 like parser rewrote most of the XML parser core, 864 provides namespace resolution and defaulted attributes, minimize memory 865 allocations and copies, namespace checking and specific error handling, 866 immutable buffers, make predefined entities static structures, etc...</li> 867 <li>rewrote all the error handling in the library, all errors can be 868 intercepted at a structured level, with precise information 869 available.</li> 870 <li>New simpler and more generic XML and HTML parser APIs, allowing to 871 easilly modify the parsing options and reuse parser context for multiple 872 consecutive documents.</li> 873 <li>Similar new APIs for the xmlReader, for options and reuse, provided new 874 functions to access content as const strings, use them for Python 875 bindings</li> 876 <li>a lot of other smaller API improvements: xmlStrPrintf (Aleksey Sanin), 877 Walker i.e. reader on a document tree based on Alfred Mickautsch code, 878 make room in nodes for line numbers, reference counting and future PSVI 879 extensions, generation of character ranges to be checked with faster 880 algorithm (William), xmlParserMaxDepth (Crutcher Dunnavant), buffer 881 access</li> 882 <li>New xmlWriter API provided by Alfred Mickautsch</li> 883 <li>Schemas: base64 support by Anthony Carrico</li> 884 <li>Parser<->HTTP integration fix, proper processing of the Mime-Type 885 and charset informations if available.</li> 886 <li>Relax-NG: bug fixes including the one reported by Martijn Faassen and 887 zeroOrMore, better error reporting.</li> 888 <li>Python bindings (St�phane Bidoul), never use stdout for errors 889 output</li> 890 <li>Portability: all the headers have macros for export and calling 891 convention definitions (Igor Zlatkovic), VMS update (Craig A. Berry), 892 Windows: threads (Jesse Pelton), Borland compiler (Eric Zurcher, Igor), 893 Mingw (Igor), typos (Mark Vakoc), beta version (Stephane Bidoul), 894 warning cleanups on AIX and MIPS compilers (William Brack), BeOS (Marcin 895 'Shard' Konicki)</li> 896 <li>Documentation fixes and README (William Brack), search fix (William), 897 tutorial updates (John Fleck), namespace docs (Stefan Kost)</li> 898 <li>Bug fixes: xmlCleanupParser (Dave Beckett), threading uninitialized 899 mutexes, HTML doctype lowercase, SAX/IO (William), compression detection 900 and restore (William), attribute declaration in DTDs (William), namespace 901 on attribute in HTML output (William), input filename (Rob Richards), 902 namespace DTD validation, xmlReplaceNode (Chris Ryland), I/O callbacks 903 (Markus Keim), CDATA serialization (Shaun McCance), xmlReader (Peter 904 Derr), high codepoint charref like &#x10FFFF;, buffer access in push 905 mode (Justin Fletcher), TLS threads on Windows (Jesse Pelton), XPath bug 906 (William), xmlCleanupParser (Marc Liyanage), CDATA output (William), HTTP 907 error handling.</li> 908 <li>xmllint options: --dtdvalidfpi for Tobias Reif, --sax1 for compat 909 testing, --nodict for building without tree dictionnary, --nocdata to 910 replace CDATA by text, --nsclean to remove surperfluous namespace 911 declarations</li> 912 <li>added xml2-config --libtool-libs option from Kevin P. Fleming</li> 913 <li>a lot of profiling and tuning of the code, speedup patch for 914 xmlSearchNs() by Luca Padovani. The xmlReader should do far less 915 allocation and it speed should get closer to SAX. Chris Anderson worked 916 on speeding and cleaning up repetitive checking code.</li> 917 <li>cleanup of "make tests"</li> 918 <li>libxml-2.0-uninstalled.pc from Malcolm Tredinnick</li> 919 <li>deactivated the broken docBook SGML parser code and plugged the XML 920 parser instead.</li> 921</ul> 922 923<h3>2.5.11: Sep 9 2003</h3> 924 925<p>A bugfix only release:</p> 926<ul> 927 <li>risk of crash in Relax-NG</li> 928 <li>risk of crash when using multithreaded programs</li> 929</ul> 930 931<h3>2.5.10: Aug 15 2003</h3> 932 933<p>A bugfixes only release</p> 934<ul> 935 <li>Windows Makefiles (William Brack)</li> 936 <li>UTF-16 support fixes (Mark Itzcovitz)</li> 937 <li>Makefile and portability (William Brack) automake, Linux alpha, Mingw 938 on Windows (Mikhail Grushinskiy)</li> 939 <li>HTML parser (Oliver Stoeneberg)</li> 940 <li>XInclude performance problem reported by Kevin Ruscoe</li> 941 <li>XML parser performance problem reported by Grant Goodale</li> 942 <li>xmlSAXParseDTD() bug fix from Malcolm Tredinnick</li> 943 <li>and a couple other cleanup</li> 944</ul> 945 946<h3>2.5.9: Aug 9 2003</h3> 947<ul> 948 <li>bugfixes: IPv6 portability, xmlHasNsProp (Markus Keim), Windows build 949 (Wiliam Brake, Jesse Pelton, Igor), Schemas (Peter Sobisch), threading 950 (Rob Richards), hexBinary type (), UTF-16 BOM (Dodji Seketeli), 951 xmlReader, Relax-NG schemas compilation, namespace handling, EXSLT (Sean 952 Griffin), HTML parsing problem (William Brack), DTD validation for mixed 953 content + namespaces, HTML serialization, library initialization, 954 progressive HTML parser</li> 955 <li>better interfaces for Relax-NG error handling (Joachim Bauch, )</li> 956 <li>adding xmlXIncludeProcessTree() for XInclud'ing in a subtree</li> 957 <li>doc fixes and improvements (John Fleck)</li> 958 <li>configure flag for -with-fexceptions when embedding in C++</li> 959 <li>couple of new UTF-8 helper functions (William Brack)</li> 960 <li>general encoding cleanup + ISO-8859-x without iconv (Peter Jacobi)</li> 961 <li>xmlTextReader cleanup + enum for node types (Bjorn Reese)</li> 962 <li>general compilation/warning cleanup Solaris/HP-UX/... (William 963 Brack)</li> 964</ul> 965 966<h3>2.5.8: Jul 6 2003</h3> 967<ul> 968 <li>bugfixes: XPath, XInclude, file/URI mapping, UTF-16 save (Mark 969 Itzcovitz), UTF-8 checking, URI saving, error printing (William Brack), 970 PI related memleak, compilation without schemas or without xpath (Joerg 971 Schmitz-Linneweber/Garry Pennington), xmlUnlinkNode problem with DTDs, 972 rpm problem on , i86_64, removed a few compilation problems from 2.5.7, 973 xmlIOParseDTD, and xmlSAXParseDTD (Malcolm Tredinnick)</li> 974 <li>portability: DJGPP (MsDos) , OpenVMS (Craig A. Berry)</li> 975 <li>William Brack fixed multithreading lock problems</li> 976 <li>IPv6 patch for FTP and HTTP accesses (Archana Shah/Wipro)</li> 977 <li>Windows fixes (Igor Zlatkovic, Eric Zurcher), threading (St�phane 978 Bidoul)</li> 979 <li>A few W3C Schemas Structure improvements</li> 980 <li>W3C Schemas Datatype improvements (Charlie Bozeman)</li> 981 <li>Python bindings for thread globals (St�phane Bidoul), and method/class 982 generator</li> 983 <li>added --nonet option to xmllint</li> 984 <li>documentation improvements (John Fleck)</li> 985</ul> 986 987<h3>2.5.7: Apr 25 2003</h3> 988<ul> 989 <li>Relax-NG: Compiling to regexp and streaming validation on top of the 990 xmlReader interface, added to xmllint --stream</li> 991 <li>xmlReader: Expand(), Next() and DOM access glue, bug fixes</li> 992 <li>Support for large files: RGN validated a 4.5GB instance</li> 993 <li>Thread support is now configured in by default</li> 994 <li>Fixes: update of the Trio code (Bjorn), WXS Date and Duration fixes 995 (Charles Bozeman), DTD and namespaces (Brent Hendricks), HTML push parser 996 and zero bytes handling, some missing Windows file path conversions, 997 behaviour of the parser and validator in the presence of "out of memory" 998 error conditions</li> 999 <li>extended the API to be able to plug a garbage collecting memory 1000 allocator, added xmlMallocAtomic() and modified the allocations 1001 accordingly.</li> 1002 <li>Performances: removed excessive malloc() calls, speedup of the push and 1003 xmlReader interfaces, removed excessive thread locking</li> 1004 <li>Documentation: man page (John Fleck), xmlReader documentation</li> 1005 <li>Python: adding binding for xmlCatalogAddLocal (Brent M Hendricks)</li> 1006</ul> 1007 1008<h3>2.5.6: Apr 1 2003</h3> 1009<ul> 1010 <li>Fixed W3C XML Schemas datatype, should be compliant now except for 1011 binHex and base64 which are not supported yet.</li> 1012 <li>bug fixes: non-ASCII IDs, HTML output, XInclude on large docs and 1013 XInclude entities handling, encoding detection on external subsets, XML 1014 Schemas bugs and memory leaks, HTML parser (James Bursa)</li> 1015 <li>portability: python/trio (Albert Chin), Sun compiler warnings</li> 1016 <li>documentation: added --relaxng option to xmllint man page (John)</li> 1017 <li>improved error reporting: xml:space, start/end tag mismatches, Relax NG 1018 errors</li> 1019</ul> 1020 1021<h3>2.5.5: Mar 24 2003</h3> 1022<ul> 1023 <li>Lot of fixes on the Relax NG implementation. More testing including 1024 DocBook and TEI examples.</li> 1025 <li>Increased the support for W3C XML Schemas datatype</li> 1026 <li>Several bug fixes in the URI handling layer</li> 1027 <li>Bug fixes: HTML parser, xmlReader, DTD validation, XPath, encoding 1028 conversion, line counting in the parser.</li> 1029 <li>Added support for $XMLLINT_INDENT environment variable, FTP delete</li> 1030 <li>Fixed the RPM spec file name</li> 1031</ul> 1032 1033<h3>2.5.4: Feb 20 2003</h3> 1034<ul> 1035 <li>Conformance testing and lot of fixes on Relax NG and XInclude 1036 implementation</li> 1037 <li>Implementation of XPointer element() scheme</li> 1038 <li>Bug fixes: XML parser, XInclude entities merge, validity checking on 1039 namespaces, 1040 <p>2 serialization bugs, node info generation problems, a DTD regexp 1041 generation problem.</p> 1042 </li> 1043 <li>Portability: windows updates and path canonicalization (Igor)</li> 1044 <li>A few typo fixes (Kjartan Maraas)</li> 1045 <li>Python bindings generator fixes (Stephane Bidoul)</li> 1046</ul> 1047 1048<h3>2.5.3: Feb 10 2003</h3> 1049<ul> 1050 <li>RelaxNG and XML Schemas datatypes improvements, and added a first 1051 version of RelaxNG Python bindings</li> 1052 <li>Fixes: XLink (Sean Chittenden), XInclude (Sean Chittenden), API fix for 1053 serializing namespace nodes, encoding conversion bug, XHTML1 1054 serialization</li> 1055 <li>Portability fixes: Windows (Igor), AMD 64bits RPM spec file</li> 1056</ul> 1057 1058<h3>2.5.2: Feb 5 2003</h3> 1059<ul> 1060 <li>First implementation of RelaxNG, added --relaxng flag to xmllint</li> 1061 <li>Schemas support now compiled in by default.</li> 1062 <li>Bug fixes: DTD validation, namespace checking, XInclude and entities, 1063 delegateURI in XML Catalogs, HTML parser, XML reader (St�phane Bidoul), 1064 XPath parser and evaluation, UTF8ToUTF8 serialization, XML reader memory 1065 consumption, HTML parser, HTML serialization in the presence of 1066 namespaces</li> 1067 <li>added an HTML API to check elements and attributes.</li> 1068 <li>Documentation improvement, PDF for the tutorial (John Fleck), doc 1069 patches (Stefan Kost)</li> 1070 <li>Portability fixes: NetBSD (Julio Merino), Windows (Igor Zlatkovic)</li> 1071 <li>Added python bindings for XPointer, contextual error reporting 1072 (St�phane Bidoul)</li> 1073 <li>URI/file escaping problems (Stefano Zacchiroli)</li> 1074</ul> 1075 1076<h3>2.5.1: Jan 8 2003</h3> 1077<ul> 1078 <li>Fixes a memory leak and configuration/compilation problems in 2.5.0</li> 1079 <li>documentation updates (John)</li> 1080 <li>a couple of XmlTextReader fixes</li> 1081</ul> 1082 1083<h3>2.5.0: Jan 6 2003</h3> 1084<ul> 1085 <li>New <a href="xmlreader.html">XmltextReader interface</a> based on C# 1086 API (with help of St�phane Bidoul)</li> 1087 <li>Windows: more exports, including the new API (Igor)</li> 1088 <li>XInclude fallback fix</li> 1089 <li>Python: bindings for the new API, packaging (St�phane Bidoul), 1090 drv_libxml2.py Python xml.sax driver (St�phane Bidoul), fixes, speedup 1091 and iterators for Python-2.2 (Hannu Krosing)</li> 1092 <li>Tutorial fixes (john Fleck and Niraj Tolia) xmllint man update 1093 (John)</li> 1094 <li>Fix an XML parser bug raised by Vyacheslav Pindyura</li> 1095 <li>Fix for VMS serialization (Nigel Hall) and config (Craig A. Berry)</li> 1096 <li>Entities handling fixes</li> 1097 <li>new API to optionally track node creation and deletion (Lukas 1098 Schroeder)</li> 1099 <li>Added documentation for the XmltextReader interface and some <a 1100 href="guidelines.html">XML guidelines</a></li> 1101</ul> 1102 1103<h3>2.4.30: Dec 12 2002</h3> 1104<ul> 1105 <li>2.4.29 broke the python bindings, rereleasing</li> 1106 <li>Improvement/fixes of the XML API generator, and couple of minor code 1107 fixes.</li> 1108</ul> 1109 1110<h3>2.4.29: Dec 11 2002</h3> 1111<ul> 1112 <li>Windows fixes (Igor): Windows CE port, pthread linking, python bindings 1113 (St�phane Bidoul), Mingw (Magnus Henoch), and export list updates</li> 1114 <li>Fix for prev in python bindings (ERDI Gergo)</li> 1115 <li>Fix for entities handling (Marcus Clarke)</li> 1116 <li>Refactored the XML and HTML dumps to a single code path, fixed XHTML1 1117 dump</li> 1118 <li>Fix for URI parsing when handling URNs with fragment identifiers</li> 1119 <li>Fix for HTTP URL escaping problem</li> 1120 <li>added an TextXmlReader (C#) like API (work in progress)</li> 1121 <li>Rewrote the API in XML generation script, includes a C parser and saves 1122 more informations needed for C# bindings</li> 1123</ul> 1124 1125<h3>2.4.28: Nov 22 2002</h3> 1126<ul> 1127 <li>a couple of python binding fixes</li> 1128 <li>2 bug fixes in the XML push parser</li> 1129 <li>potential memory leak removed (Martin Stoilov)</li> 1130 <li>fix to the configure script for Unix (Dimitri Papadopoulos)</li> 1131 <li>added encoding support for XInclude parse="text"</li> 1132 <li>autodetection of XHTML1 and specific serialization rules added</li> 1133 <li>nasty threading bug fixed (William Brack)</li> 1134</ul> 1135 1136<h3>2.4.27: Nov 17 2002</h3> 1137<ul> 1138 <li>fixes for the Python bindings</li> 1139 <li>a number of bug fixes: SGML catalogs, xmlParseBalancedChunkMemory(), 1140 HTML parser, Schemas (Charles Bozeman), document fragment support 1141 (Christian Glahn), xmlReconciliateNs (Brian Stafford), XPointer, 1142 xmlFreeNode(), xmlSAXParseMemory (Peter Jones), xmlGetNodePath (Petr 1143 Pajas), entities processing</li> 1144 <li>added grep to xmllint --shell</li> 1145 <li>VMS update patch from Craig A. Berry</li> 1146 <li>cleanup of the Windows build with support for more compilers (Igor), 1147 better thread support on Windows</li> 1148 <li>cleanup of Unix Makefiles and spec file</li> 1149 <li>Improvements to the documentation (John Fleck)</li> 1150</ul> 1151 1152<h3>2.4.26: Oct 18 2002</h3> 1153<ul> 1154 <li>Patches for Windows CE port, improvements on Windows paths handling</li> 1155 <li>Fixes to the validation code (DTD and Schemas), xmlNodeGetPath() , 1156 HTML serialization, Namespace compliance, and a number of small 1157 problems</li> 1158</ul> 1159 1160<h3>2.4.25: Sep 26 2002</h3> 1161<ul> 1162 <li>A number of bug fixes: XPath, validation, Python bindings, DOM and 1163 tree, xmlI/O, Html</li> 1164 <li>Serious rewrite of XInclude</li> 1165 <li>Made XML Schemas regexp part of the default build and APIs, small fix 1166 and improvement of the regexp core</li> 1167 <li>Changed the validation code to reuse XML Schemas regexp APIs</li> 1168 <li>Better handling of Windows file paths, improvement of Makefiles (Igor, 1169 Daniel Gehriger, Mark Vakoc)</li> 1170 <li>Improved the python I/O bindings, the tests, added resolver and regexp 1171 APIs</li> 1172 <li>New logos from Marc Liyanage</li> 1173 <li>Tutorial improvements: John Fleck, Christopher Harris</li> 1174 <li>Makefile: Fixes for AMD x86_64 (Mandrake), DESTDIR (Christophe 1175 Merlet)</li> 1176 <li>removal of all stderr/perror use for error reporting</li> 1177 <li>Better error reporting: XPath and DTD validation</li> 1178 <li>update of the trio portability layer (Bjorn Reese)</li> 1179</ul> 1180 1181<p><strong>2.4.24: Aug 22 2002</strong></p> 1182<ul> 1183 <li>XPath fixes (William), xf:escape-uri() (Wesley Terpstra)</li> 1184 <li>Python binding fixes: makefiles (William), generator, rpm build, x86-64 1185 (fcrozat)</li> 1186 <li>HTML <style> and boolean attributes serializer fixes</li> 1187 <li>C14N improvements by Aleksey</li> 1188 <li>doc cleanups: Rick Jones</li> 1189 <li>Windows compiler makefile updates: Igor and Elizabeth Barham</li> 1190 <li>XInclude: implementation of fallback and xml:base fixup added</li> 1191</ul> 1192 1193<h3>2.4.23: July 6 2002</h3> 1194<ul> 1195 <li>performances patches: Peter Jacobi</li> 1196 <li>c14n fixes, testsuite and performances: Aleksey Sanin</li> 1197 <li>added xmlDocFormatDump: Chema Celorio</li> 1198 <li>new tutorial: John Fleck</li> 1199 <li>new hash functions and performances: Sander Vesik, portability fix from 1200 Peter Jacobi</li> 1201 <li>a number of bug fixes: XPath (William Brack, Richard Jinks), XML and 1202 HTML parsers, ID lookup function</li> 1203 <li>removal of all remaining sprintf: Aleksey Sanin</li> 1204</ul> 1205 1206<h3>2.4.22: May 27 2002</h3> 1207<ul> 1208 <li>a number of bug fixes: configure scripts, base handling, parser, memory 1209 usage, HTML parser, XPath, documentation (Christian Cornelssen), 1210 indentation, URI parsing</li> 1211 <li>Optimizations for XMLSec, fixing and making public some of the network 1212 protocol handlers (Aleksey)</li> 1213 <li>performance patch from Gary Pennington</li> 1214 <li>Charles Bozeman provided date and time support for XML Schemas 1215 datatypes</li> 1216</ul> 1217 1218<h3>2.4.21: Apr 29 2002</h3> 1219 1220<p>This release is both a bug fix release and also contains the early XML 1221Schemas <a href="http://www.w3.org/TR/xmlschema-1/">structures</a> and <a 1222href="http://www.w3.org/TR/xmlschema-2/">datatypes</a> code, beware, all 1223interfaces are likely to change, there is huge holes, it is clearly a work in 1224progress and don't even think of putting this code in a production system, 1225it's actually not compiled in by default. The real fixes are:</p> 1226<ul> 1227 <li>a couple of bugs or limitations introduced in 2.4.20</li> 1228 <li>patches for Borland C++ and MSC by Igor</li> 1229 <li>some fixes on XPath strings and conformance patches by Richard 1230 Jinks</li> 1231 <li>patch from Aleksey for the ExcC14N specification</li> 1232 <li>OSF/1 bug fix by Bjorn</li> 1233</ul> 1234 1235<h3>2.4.20: Apr 15 2002</h3> 1236<ul> 1237 <li>bug fixes: file descriptor leak, XPath, HTML output, DTD validation</li> 1238 <li>XPath conformance testing by Richard Jinks</li> 1239 <li>Portability fixes: Solaris, MPE/iX, Windows, OSF/1, python bindings, 1240 libxml.m4</li> 1241</ul> 1242 1243<h3>2.4.19: Mar 25 2002</h3> 1244<ul> 1245 <li>bug fixes: half a dozen XPath bugs, Validation, ISO-Latin to UTF8 1246 encoder</li> 1247 <li>portability fixes in the HTTP code</li> 1248 <li>memory allocation checks using valgrind, and profiling tests</li> 1249 <li>revamp of the Windows build and Makefiles</li> 1250</ul> 1251 1252<h3>2.4.18: Mar 18 2002</h3> 1253<ul> 1254 <li>bug fixes: tree, SAX, canonicalization, validation, portability, 1255 XPath</li> 1256 <li>removed the --with-buffer option it was becoming unmaintainable</li> 1257 <li>serious cleanup of the Python makefiles</li> 1258 <li>speedup patch to XPath very effective for DocBook stylesheets</li> 1259 <li>Fixes for Windows build, cleanup of the documentation</li> 1260</ul> 1261 1262<h3>2.4.17: Mar 8 2002</h3> 1263<ul> 1264 <li>a lot of bug fixes, including "namespace nodes have no parents in 1265 XPath"</li> 1266 <li>fixed/improved the Python wrappers, added more examples and more 1267 regression tests, XPath extension functions can now return node-sets</li> 1268 <li>added the XML Canonicalization support from Aleksey Sanin</li> 1269</ul> 1270 1271<h3>2.4.16: Feb 20 2002</h3> 1272<ul> 1273 <li>a lot of bug fixes, most of them were triggered by the XML Testsuite 1274 from OASIS and W3C. Compliance has been significantly improved.</li> 1275 <li>a couple of portability fixes too.</li> 1276</ul> 1277 1278<h3>2.4.15: Feb 11 2002</h3> 1279<ul> 1280 <li>Fixed the Makefiles, especially the python module ones</li> 1281 <li>A few bug fixes and cleanup</li> 1282 <li>Includes cleanup</li> 1283</ul> 1284 1285<h3>2.4.14: Feb 8 2002</h3> 1286<ul> 1287 <li>Change of License to the <a 1288 href="http://www.opensource.org/licenses/mit-license.html">MIT 1289 License</a> basically for integration in XFree86 codebase, and removing 1290 confusion around the previous dual-licensing</li> 1291 <li>added Python bindings, beta software but should already be quite 1292 complete</li> 1293 <li>a large number of fixes and cleanups, especially for all tree 1294 manipulations</li> 1295 <li>cleanup of the headers, generation of a reference API definition in 1296 XML</li> 1297</ul> 1298 1299<h3>2.4.13: Jan 14 2002</h3> 1300<ul> 1301 <li>update of the documentation: John Fleck and Charlie Bozeman</li> 1302 <li>cleanup of timing code from Justin Fletcher</li> 1303 <li>fixes for Windows and initial thread support on Win32: Igor and Serguei 1304 Narojnyi</li> 1305 <li>Cygwin patch from Robert Collins</li> 1306 <li>added xmlSetEntityReferenceFunc() for Keith Isdale work on xsldbg</li> 1307</ul> 1308 1309<h3>2.4.12: Dec 7 2001</h3> 1310<ul> 1311 <li>a few bug fixes: thread (Gary Pennington), xmllint (Geert Kloosterman), 1312 XML parser (Robin Berjon), XPointer (Danny Jamshy), I/O cleanups 1313 (robert)</li> 1314 <li>Eric Lavigne contributed project files for MacOS</li> 1315 <li>some makefiles cleanups</li> 1316</ul> 1317 1318<h3>2.4.11: Nov 26 2001</h3> 1319<ul> 1320 <li>fixed a couple of errors in the includes, fixed a few bugs, some code 1321 cleanups</li> 1322 <li>xmllint man pages improvement by Heiko Rupp</li> 1323 <li>updated VMS build instructions from John A Fotheringham</li> 1324 <li>Windows Makefiles updates from Igor</li> 1325</ul> 1326 1327<h3>2.4.10: Nov 10 2001</h3> 1328<ul> 1329 <li>URI escaping fix (Joel Young)</li> 1330 <li>added xmlGetNodePath() (for paths or XPointers generation)</li> 1331 <li>Fixes namespace handling problems when using DTD and validation</li> 1332 <li>improvements on xmllint: Morus Walter patches for --format and 1333 --encode, Stefan Kost and Heiko Rupp improvements on the --shell</li> 1334 <li>fixes for xmlcatalog linking pointed by Weiqi Gao</li> 1335 <li>fixes to the HTML parser</li> 1336</ul> 1337 1338<h3>2.4.9: Nov 6 2001</h3> 1339<ul> 1340 <li>fixes more catalog bugs</li> 1341 <li>avoid a compilation problem, improve xmlGetLineNo()</li> 1342</ul> 1343 1344<h3>2.4.8: Nov 4 2001</h3> 1345<ul> 1346 <li>fixed SGML catalogs broken in previous release, updated xmlcatalog 1347 tool</li> 1348 <li>fixed a compile errors and some includes troubles.</li> 1349</ul> 1350 1351<h3>2.4.7: Oct 30 2001</h3> 1352<ul> 1353 <li>exported some debugging interfaces</li> 1354 <li>serious rewrite of the catalog code</li> 1355 <li>integrated Gary Pennington thread safety patch, added configure option 1356 and regression tests</li> 1357 <li>removed an HTML parser bug</li> 1358 <li>fixed a couple of potentially serious validation bugs</li> 1359 <li>integrated the SGML DocBook support in xmllint</li> 1360 <li>changed the nanoftp anonymous login passwd</li> 1361 <li>some I/O cleanup and a couple of interfaces for Perl wrapper</li> 1362 <li>general bug fixes</li> 1363 <li>updated xmllint man page by John Fleck</li> 1364 <li>some VMS and Windows updates</li> 1365</ul> 1366 1367<h3>2.4.6: Oct 10 2001</h3> 1368<ul> 1369 <li>added an updated man pages by John Fleck</li> 1370 <li>portability and configure fixes</li> 1371 <li>an infinite loop on the HTML parser was removed (William)</li> 1372 <li>Windows makefile patches from Igor</li> 1373 <li>fixed half a dozen bugs reported for libxml or libxslt</li> 1374 <li>updated xmlcatalog to be able to modify SGML super catalogs</li> 1375</ul> 1376 1377<h3>2.4.5: Sep 14 2001</h3> 1378<ul> 1379 <li>Remove a few annoying bugs in 2.4.4</li> 1380 <li>forces the HTML serializer to output decimal charrefs since some 1381 version of Netscape can't handle hexadecimal ones</li> 1382</ul> 1383 1384<h3>1.8.16: Sep 14 2001</h3> 1385<ul> 1386 <li>maintenance release of the old libxml1 branch, couple of bug and 1387 portability fixes</li> 1388</ul> 1389 1390<h3>2.4.4: Sep 12 2001</h3> 1391<ul> 1392 <li>added --convert to xmlcatalog, bug fixes and cleanups of XML 1393 Catalog</li> 1394 <li>a few bug fixes and some portability changes</li> 1395 <li>some documentation cleanups</li> 1396</ul> 1397 1398<h3>2.4.3: Aug 23 2001</h3> 1399<ul> 1400 <li>XML Catalog support see the doc</li> 1401 <li>New NaN/Infinity floating point code</li> 1402 <li>A few bug fixes</li> 1403</ul> 1404 1405<h3>2.4.2: Aug 15 2001</h3> 1406<ul> 1407 <li>adds xmlLineNumbersDefault() to control line number generation</li> 1408 <li>lot of bug fixes</li> 1409 <li>the Microsoft MSC projects files should now be up to date</li> 1410 <li>inheritance of namespaces from DTD defaulted attributes</li> 1411 <li>fixes a serious potential security bug</li> 1412 <li>added a --format option to xmllint</li> 1413</ul> 1414 1415<h3>2.4.1: July 24 2001</h3> 1416<ul> 1417 <li>possibility to keep line numbers in the tree</li> 1418 <li>some computation NaN fixes</li> 1419 <li>extension of the XPath API</li> 1420 <li>cleanup for alpha and ia64 targets</li> 1421 <li>patch to allow saving through HTTP PUT or POST</li> 1422</ul> 1423 1424<h3>2.4.0: July 10 2001</h3> 1425<ul> 1426 <li>Fixed a few bugs in XPath, validation, and tree handling.</li> 1427 <li>Fixed XML Base implementation, added a couple of examples to the 1428 regression tests</li> 1429 <li>A bit of cleanup</li> 1430</ul> 1431 1432<h3>2.3.14: July 5 2001</h3> 1433<ul> 1434 <li>fixed some entities problems and reduce memory requirement when 1435 substituting them</li> 1436 <li>lots of improvements in the XPath queries interpreter can be 1437 substantially faster</li> 1438 <li>Makefiles and configure cleanups</li> 1439 <li>Fixes to XPath variable eval, and compare on empty node set</li> 1440 <li>HTML tag closing bug fixed</li> 1441 <li>Fixed an URI reference computation problem when validating</li> 1442</ul> 1443 1444<h3>2.3.13: June 28 2001</h3> 1445<ul> 1446 <li>2.3.12 configure.in was broken as well as the push mode XML parser</li> 1447 <li>a few more fixes for compilation on Windows MSC by Yon Derek</li> 1448</ul> 1449 1450<h3>1.8.14: June 28 2001</h3> 1451<ul> 1452 <li>Zbigniew Chyla gave a patch to use the old XML parser in push mode</li> 1453 <li>Small Makefile fix</li> 1454</ul> 1455 1456<h3>2.3.12: June 26 2001</h3> 1457<ul> 1458 <li>lots of cleanup</li> 1459 <li>a couple of validation fix</li> 1460 <li>fixed line number counting</li> 1461 <li>fixed serious problems in the XInclude processing</li> 1462 <li>added support for UTF8 BOM at beginning of entities</li> 1463 <li>fixed a strange gcc optimizer bugs in xpath handling of float, gcc-3.0 1464 miscompile uri.c (William), Thomas Leitner provided a fix for the 1465 optimizer on Tru64</li> 1466 <li>incorporated Yon Derek and Igor Zlatkovic fixes and improvements for 1467 compilation on Windows MSC</li> 1468 <li>update of libxml-doc.el (Felix Natter)</li> 1469 <li>fixed 2 bugs in URI normalization code</li> 1470</ul> 1471 1472<h3>2.3.11: June 17 2001</h3> 1473<ul> 1474 <li>updates to trio, Makefiles and configure should fix some portability 1475 problems (alpha)</li> 1476 <li>fixed some HTML serialization problems (pre, script, and block/inline 1477 handling), added encoding aware APIs, cleanup of this code</li> 1478 <li>added xmlHasNsProp()</li> 1479 <li>implemented a specific PI for encoding support in the DocBook SGML 1480 parser</li> 1481 <li>some XPath fixes (-Infinity, / as a function parameter and namespaces 1482 node selection)</li> 1483 <li>fixed a performance problem and an error in the validation code</li> 1484 <li>fixed XInclude routine to implement the recursive behaviour</li> 1485 <li>fixed xmlFreeNode problem when libxml is included statically twice</li> 1486 <li>added --version to xmllint for bug reports</li> 1487</ul> 1488 1489<h3>2.3.10: June 1 2001</h3> 1490<ul> 1491 <li>fixed the SGML catalog support</li> 1492 <li>a number of reported bugs got fixed, in XPath, iconv detection, 1493 XInclude processing</li> 1494 <li>XPath string function should now handle unicode correctly</li> 1495</ul> 1496 1497<h3>2.3.9: May 19 2001</h3> 1498 1499<p>Lots of bugfixes, and added a basic SGML catalog support:</p> 1500<ul> 1501 <li>HTML push bugfix #54891 and another patch from Jonas Borgstr�m</li> 1502 <li>some serious speed optimization again</li> 1503 <li>some documentation cleanups</li> 1504 <li>trying to get better linking on Solaris (-R)</li> 1505 <li>XPath API cleanup from Thomas Broyer</li> 1506 <li>Validation bug fixed #54631, added a patch from Gary Pennington, fixed 1507 xmlValidGetValidElements()</li> 1508 <li>Added an INSTALL file</li> 1509 <li>Attribute removal added to API: #54433</li> 1510 <li>added a basic support for SGML catalogs</li> 1511 <li>fixed xmlKeepBlanksDefault(0) API</li> 1512 <li>bugfix in xmlNodeGetLang()</li> 1513 <li>fixed a small configure portability problem</li> 1514 <li>fixed an inversion of SYSTEM and PUBLIC identifier in HTML document</li> 1515</ul> 1516 1517<h3>1.8.13: May 14 2001</h3> 1518<ul> 1519 <li>bugfixes release of the old libxml1 branch used by Gnome</li> 1520</ul> 1521 1522<h3>2.3.8: May 3 2001</h3> 1523<ul> 1524 <li>Integrated an SGML DocBook parser for the Gnome project</li> 1525 <li>Fixed a few things in the HTML parser</li> 1526 <li>Fixed some XPath bugs raised by XSLT use, tried to fix the floating 1527 point portability issue</li> 1528 <li>Speed improvement (8M/s for SAX, 3M/s for DOM, 1.5M/s for 1529 DOM+validation using the XML REC as input and a 700MHz celeron).</li> 1530 <li>incorporated more Windows cleanup</li> 1531 <li>added xmlSaveFormatFile()</li> 1532 <li>fixed problems in copying nodes with entities references (gdome)</li> 1533 <li>removed some troubles surrounding the new validation module</li> 1534</ul> 1535 1536<h3>2.3.7: April 22 2001</h3> 1537<ul> 1538 <li>lots of small bug fixes, corrected XPointer</li> 1539 <li>Non deterministic content model validation support</li> 1540 <li>added xmlDocCopyNode for gdome2</li> 1541 <li>revamped the way the HTML parser handles end of tags</li> 1542 <li>XPath: corrections of namespaces support and number formatting</li> 1543 <li>Windows: Igor Zlatkovic patches for MSC compilation</li> 1544 <li>HTML output fixes from P C Chow and William M. Brack</li> 1545 <li>Improved validation speed sensible for DocBook</li> 1546 <li>fixed a big bug with ID declared in external parsed entities</li> 1547 <li>portability fixes, update of Trio from Bjorn Reese</li> 1548</ul> 1549 1550<h3>2.3.6: April 8 2001</h3> 1551<ul> 1552 <li>Code cleanup using extreme gcc compiler warning options, found and 1553 cleared half a dozen potential problem</li> 1554 <li>the Eazel team found an XML parser bug</li> 1555 <li>cleaned up the user of some of the string formatting function. used the 1556 trio library code to provide the one needed when the platform is missing 1557 them</li> 1558 <li>xpath: removed a memory leak and fixed the predicate evaluation 1559 problem, extended the testsuite and cleaned up the result. XPointer seems 1560 broken ...</li> 1561</ul> 1562 1563<h3>2.3.5: Mar 23 2001</h3> 1564<ul> 1565 <li>Biggest change is separate parsing and evaluation of XPath expressions, 1566 there is some new APIs for this too</li> 1567 <li>included a number of bug fixes(XML push parser, 51876, notations, 1568 52299)</li> 1569 <li>Fixed some portability issues</li> 1570</ul> 1571 1572<h3>2.3.4: Mar 10 2001</h3> 1573<ul> 1574 <li>Fixed bugs #51860 and #51861</li> 1575 <li>Added a global variable xmlDefaultBufferSize to allow default buffer 1576 size to be application tunable.</li> 1577 <li>Some cleanup in the validation code, still a bug left and this part 1578 should probably be rewritten to support ambiguous content model :-\</li> 1579 <li>Fix a couple of serious bugs introduced or raised by changes in 2.3.3 1580 parser</li> 1581 <li>Fixed another bug in xmlNodeGetContent()</li> 1582 <li>Bjorn fixed XPath node collection and Number formatting</li> 1583 <li>Fixed a loop reported in the HTML parsing</li> 1584 <li>blank space are reported even if the Dtd content model proves that they 1585 are formatting spaces, this is for XML conformance</li> 1586</ul> 1587 1588<h3>2.3.3: Mar 1 2001</h3> 1589<ul> 1590 <li>small change in XPath for XSLT</li> 1591 <li>documentation cleanups</li> 1592 <li>fix in validation by Gary Pennington</li> 1593 <li>serious parsing performances improvements</li> 1594</ul> 1595 1596<h3>2.3.2: Feb 24 2001</h3> 1597<ul> 1598 <li>chasing XPath bugs, found a bunch, completed some TODO</li> 1599 <li>fixed a Dtd parsing bug</li> 1600 <li>fixed a bug in xmlNodeGetContent</li> 1601 <li>ID/IDREF support partly rewritten by Gary Pennington</li> 1602</ul> 1603 1604<h3>2.3.1: Feb 15 2001</h3> 1605<ul> 1606 <li>some XPath and HTML bug fixes for XSLT</li> 1607 <li>small extension of the hash table interfaces for DOM gdome2 1608 implementation</li> 1609 <li>A few bug fixes</li> 1610</ul> 1611 1612<h3>2.3.0: Feb 8 2001 (2.2.12 was on 25 Jan but I didn't kept track)</h3> 1613<ul> 1614 <li>Lots of XPath bug fixes</li> 1615 <li>Add a mode with Dtd lookup but without validation error reporting for 1616 XSLT</li> 1617 <li>Add support for text node without escaping (XSLT)</li> 1618 <li>bug fixes for xmlCheckFilename</li> 1619 <li>validation code bug fixes from Gary Pennington</li> 1620 <li>Patch from Paul D. Smith correcting URI path normalization</li> 1621 <li>Patch to allow simultaneous install of libxml-devel and 1622 libxml2-devel</li> 1623 <li>the example Makefile is now fixed</li> 1624 <li>added HTML to the RPM packages</li> 1625 <li>tree copying bugfixes</li> 1626 <li>updates to Windows makefiles</li> 1627 <li>optimization patch from Bjorn Reese</li> 1628</ul> 1629 1630<h3>2.2.11: Jan 4 2001</h3> 1631<ul> 1632 <li>bunch of bug fixes (memory I/O, xpath, ftp/http, ...)</li> 1633 <li>added htmlHandleOmittedElem()</li> 1634 <li>Applied Bjorn Reese's IPV6 first patch</li> 1635 <li>Applied Paul D. Smith patches for validation of XInclude results</li> 1636 <li>added XPointer xmlns() new scheme support</li> 1637</ul> 1638 1639<h3>2.2.10: Nov 25 2000</h3> 1640<ul> 1641 <li>Fix the Windows problems of 2.2.8</li> 1642 <li>integrate OpenVMS patches</li> 1643 <li>better handling of some nasty HTML input</li> 1644 <li>Improved the XPointer implementation</li> 1645 <li>integrate a number of provided patches</li> 1646</ul> 1647 1648<h3>2.2.9: Nov 25 2000</h3> 1649<ul> 1650 <li>erroneous release :-(</li> 1651</ul> 1652 1653<h3>2.2.8: Nov 13 2000</h3> 1654<ul> 1655 <li>First version of <a href="http://www.w3.org/TR/xinclude">XInclude</a> 1656 support</li> 1657 <li>Patch in conditional section handling</li> 1658 <li>updated MS compiler project</li> 1659 <li>fixed some XPath problems</li> 1660 <li>added an URI escaping function</li> 1661 <li>some other bug fixes</li> 1662</ul> 1663 1664<h3>2.2.7: Oct 31 2000</h3> 1665<ul> 1666 <li>added message redirection</li> 1667 <li>XPath improvements (thanks TOM !)</li> 1668 <li>xmlIOParseDTD() added</li> 1669 <li>various small fixes in the HTML, URI, HTTP and XPointer support</li> 1670 <li>some cleanup of the Makefile, autoconf and the distribution content</li> 1671</ul> 1672 1673<h3>2.2.6: Oct 25 2000:</h3> 1674<ul> 1675 <li>Added an hash table module, migrated a number of internal structure to 1676 those</li> 1677 <li>Fixed a posteriori validation problems</li> 1678 <li>HTTP module cleanups</li> 1679 <li>HTML parser improvements (tag errors, script/style handling, attribute 1680 normalization)</li> 1681 <li>coalescing of adjacent text nodes</li> 1682 <li>couple of XPath bug fixes, exported the internal API</li> 1683</ul> 1684 1685<h3>2.2.5: Oct 15 2000:</h3> 1686<ul> 1687 <li>XPointer implementation and testsuite</li> 1688 <li>Lot of XPath fixes, added variable and functions registration, more 1689 tests</li> 1690 <li>Portability fixes, lots of enhancements toward an easy Windows build 1691 and release</li> 1692 <li>Late validation fixes</li> 1693 <li>Integrated a lot of contributed patches</li> 1694 <li>added memory management docs</li> 1695 <li>a performance problem when using large buffer seems fixed</li> 1696</ul> 1697 1698<h3>2.2.4: Oct 1 2000:</h3> 1699<ul> 1700 <li>main XPath problem fixed</li> 1701 <li>Integrated portability patches for Windows</li> 1702 <li>Serious bug fixes on the URI and HTML code</li> 1703</ul> 1704 1705<h3>2.2.3: Sep 17 2000</h3> 1706<ul> 1707 <li>bug fixes</li> 1708 <li>cleanup of entity handling code</li> 1709 <li>overall review of all loops in the parsers, all sprintf usage has been 1710 checked too</li> 1711 <li>Far better handling of larges Dtd. Validating against DocBook XML Dtd 1712 works smoothly now.</li> 1713</ul> 1714 1715<h3>1.8.10: Sep 6 2000</h3> 1716<ul> 1717 <li>bug fix release for some Gnome projects</li> 1718</ul> 1719 1720<h3>2.2.2: August 12 2000</h3> 1721<ul> 1722 <li>mostly bug fixes</li> 1723 <li>started adding routines to access xml parser context options</li> 1724</ul> 1725 1726<h3>2.2.1: July 21 2000</h3> 1727<ul> 1728 <li>a purely bug fixes release</li> 1729 <li>fixed an encoding support problem when parsing from a memory block</li> 1730 <li>fixed a DOCTYPE parsing problem</li> 1731 <li>removed a bug in the function allowing to override the memory 1732 allocation routines</li> 1733</ul> 1734 1735<h3>2.2.0: July 14 2000</h3> 1736<ul> 1737 <li>applied a lot of portability fixes</li> 1738 <li>better encoding support/cleanup and saving (content is now always 1739 encoded in UTF-8)</li> 1740 <li>the HTML parser now correctly handles encodings</li> 1741 <li>added xmlHasProp()</li> 1742 <li>fixed a serious problem with &#38;</li> 1743 <li>propagated the fix to FTP client</li> 1744 <li>cleanup, bugfixes, etc ...</li> 1745 <li>Added a page about <a href="encoding.html">libxml Internationalization 1746 support</a></li> 1747</ul> 1748 1749<h3>1.8.9: July 9 2000</h3> 1750<ul> 1751 <li>fixed the spec the RPMs should be better</li> 1752 <li>fixed a serious bug in the FTP implementation, released 1.8.9 to solve 1753 rpmfind users problem</li> 1754</ul> 1755 1756<h3>2.1.1: July 1 2000</h3> 1757<ul> 1758 <li>fixes a couple of bugs in the 2.1.0 packaging</li> 1759 <li>improvements on the HTML parser</li> 1760</ul> 1761 1762<h3>2.1.0 and 1.8.8: June 29 2000</h3> 1763<ul> 1764 <li>1.8.8 is mostly a commodity package for upgrading to libxml2 according 1765 to <a href="upgrade.html">new instructions</a>. It fixes a nasty problem 1766 about &#38; charref parsing</li> 1767 <li>2.1.0 also ease the upgrade from libxml v1 to the recent version. it 1768 also contains numerous fixes and enhancements: 1769 <ul> 1770 <li>added xmlStopParser() to stop parsing</li> 1771 <li>improved a lot parsing speed when there is large CDATA blocs</li> 1772 <li>includes XPath patches provided by Picdar Technology</li> 1773 <li>tried to fix as much as possible DTD validation and namespace 1774 related problems</li> 1775 <li>output to a given encoding has been added/tested</li> 1776 <li>lot of various fixes</li> 1777 </ul> 1778 </li> 1779</ul> 1780 1781<h3>2.0.0: Apr 12 2000</h3> 1782<ul> 1783 <li>First public release of libxml2. If you are using libxml, it's a good 1784 idea to check the 1.x to 2.x upgrade instructions. NOTE: while initially 1785 scheduled for Apr 3 the release occurred only on Apr 12 due to massive 1786 workload.</li> 1787 <li>The include are now located under $prefix/include/libxml (instead of 1788 $prefix/include/gnome-xml), they also are referenced by 1789 <pre>#include <libxml/xxx.h></pre> 1790 <p>instead of</p> 1791 <pre>#include "xxx.h"</pre> 1792 </li> 1793 <li>a new URI module for parsing URIs and following strictly RFC 2396</li> 1794 <li>the memory allocation routines used by libxml can now be overloaded 1795 dynamically by using xmlMemSetup()</li> 1796 <li>The previously CVS only tool tester has been renamed 1797 <strong>xmllint</strong> and is now installed as part of the libxml2 1798 package</li> 1799 <li>The I/O interface has been revamped. There is now ways to plug in 1800 specific I/O modules, either at the URI scheme detection level using 1801 xmlRegisterInputCallbacks() or by passing I/O functions when creating a 1802 parser context using xmlCreateIOParserCtxt()</li> 1803 <li>there is a C preprocessor macro LIBXML_VERSION providing the version 1804 number of the libxml module in use</li> 1805 <li>a number of optional features of libxml can now be excluded at 1806 configure time (FTP/HTTP/HTML/XPath/Debug)</li> 1807</ul> 1808 1809<h3>2.0.0beta: Mar 14 2000</h3> 1810<ul> 1811 <li>This is a first Beta release of libxml version 2</li> 1812 <li>It's available only from<a href="ftp://xmlsoft.org/">xmlsoft.org 1813 FTP</a>, it's packaged as libxml2-2.0.0beta and available as tar and 1814 RPMs</li> 1815 <li>This version is now the head in the Gnome CVS base, the old one is 1816 available under the tag LIB_XML_1_X</li> 1817 <li>This includes a very large set of changes. From a programmatic point 1818 of view applications should not have to be modified too much, check the 1819 <a href="upgrade.html">upgrade page</a></li> 1820 <li>Some interfaces may changes (especially a bit about encoding).</li> 1821 <li>the updates includes: 1822 <ul> 1823 <li>fix I18N support. ISO-Latin-x/UTF-8/UTF-16 (nearly) seems correctly 1824 handled now</li> 1825 <li>Better handling of entities, especially well-formedness checking 1826 and proper PEref extensions in external subsets</li> 1827 <li>DTD conditional sections</li> 1828 <li>Validation now correctly handle entities content</li> 1829 <li><a href="http://rpmfind.net/tools/gdome/messages/0039.html">change 1830 structures to accommodate DOM</a></li> 1831 </ul> 1832 </li> 1833 <li>Serious progress were made toward compliance, <a 1834 href="conf/result.html">here are the result of the test</a> against the 1835 OASIS testsuite (except the Japanese tests since I don't support that 1836 encoding yet). This URL is rebuilt every couple of hours using the CVS 1837 head version.</li> 1838</ul> 1839 1840<h3>1.8.7: Mar 6 2000</h3> 1841<ul> 1842 <li>This is a bug fix release:</li> 1843 <li>It is possible to disable the ignorable blanks heuristic used by 1844 libxml-1.x, a new function xmlKeepBlanksDefault(0) will allow this. Note 1845 that for adherence to XML spec, this behaviour will be disabled by 1846 default in 2.x . The same function will allow to keep compatibility for 1847 old code.</li> 1848 <li>Blanks in <a> </a> constructs are not ignored anymore, 1849 avoiding heuristic is really the Right Way :-\</li> 1850 <li>The unchecked use of snprintf which was breaking libxml-1.8.6 1851 compilation on some platforms has been fixed</li> 1852 <li>nanoftp.c nanohttp.c: Fixed '#' and '?' stripping when processing 1853 URIs</li> 1854</ul> 1855 1856<h3>1.8.6: Jan 31 2000</h3> 1857<ul> 1858 <li>added a nanoFTP transport module, debugged until the new version of <a 1859 href="http://rpmfind.net/linux/rpm2html/rpmfind.html">rpmfind</a> can use 1860 it without troubles</li> 1861</ul> 1862 1863<h3>1.8.5: Jan 21 2000</h3> 1864<ul> 1865 <li>adding APIs to parse a well balanced chunk of XML (production <a 1866 href="http://www.w3.org/TR/REC-xml#NT-content">[43] content</a> of the 1867 XML spec)</li> 1868 <li>fixed a hideous bug in xmlGetProp pointed by Rune.Djurhuus@fast.no</li> 1869 <li>Jody Goldberg <jgoldberg@home.com> provided another patch trying 1870 to solve the zlib checks problems</li> 1871 <li>The current state in gnome CVS base is expected to ship as 1.8.5 with 1872 gnumeric soon</li> 1873</ul> 1874 1875<h3>1.8.4: Jan 13 2000</h3> 1876<ul> 1877 <li>bug fixes, reintroduced xmlNewGlobalNs(), fixed xmlNewNs()</li> 1878 <li>all exit() call should have been removed from libxml</li> 1879 <li>fixed a problem with INCLUDE_WINSOCK on WIN32 platform</li> 1880 <li>added newDocFragment()</li> 1881</ul> 1882 1883<h3>1.8.3: Jan 5 2000</h3> 1884<ul> 1885 <li>a Push interface for the XML and HTML parsers</li> 1886 <li>a shell-like interface to the document tree (try tester --shell :-)</li> 1887 <li>lots of bug fixes and improvement added over XMas holidays</li> 1888 <li>fixed the DTD parsing code to work with the xhtml DTD</li> 1889 <li>added xmlRemoveProp(), xmlRemoveID() and xmlRemoveRef()</li> 1890 <li>Fixed bugs in xmlNewNs()</li> 1891 <li>External entity loading code has been revamped, now it uses 1892 xmlLoadExternalEntity(), some fix on entities processing were added</li> 1893 <li>cleaned up WIN32 includes of socket stuff</li> 1894</ul> 1895 1896<h3>1.8.2: Dec 21 1999</h3> 1897<ul> 1898 <li>I got another problem with includes and C++, I hope this issue is fixed 1899 for good this time</li> 1900 <li>Added a few tree modification functions: xmlReplaceNode, 1901 xmlAddPrevSibling, xmlAddNextSibling, xmlNodeSetName and 1902 xmlDocSetRootElement</li> 1903 <li>Tried to improve the HTML output with help from <a 1904 href="mailto:clahey@umich.edu">Chris Lahey</a></li> 1905</ul> 1906 1907<h3>1.8.1: Dec 18 1999</h3> 1908<ul> 1909 <li>various patches to avoid troubles when using libxml with C++ compilers 1910 the "namespace" keyword and C escaping in include files</li> 1911 <li>a problem in one of the core macros IS_CHAR was corrected</li> 1912 <li>fixed a bug introduced in 1.8.0 breaking default namespace processing, 1913 and more specifically the Dia application</li> 1914 <li>fixed a posteriori validation (validation after parsing, or by using a 1915 Dtd not specified in the original document)</li> 1916 <li>fixed a bug in</li> 1917</ul> 1918 1919<h3>1.8.0: Dec 12 1999</h3> 1920<ul> 1921 <li>cleanup, especially memory wise</li> 1922 <li>the parser should be more reliable, especially the HTML one, it should 1923 not crash, whatever the input !</li> 1924 <li>Integrated various patches, especially a speedup improvement for large 1925 dataset from <a href="mailto:cnygard@bellatlantic.net">Carl Nygard</a>, 1926 configure with --with-buffers to enable them.</li> 1927 <li>attribute normalization, oops should have been added long ago !</li> 1928 <li>attributes defaulted from DTDs should be available, xmlSetProp() now 1929 does entities escaping by default.</li> 1930</ul> 1931 1932<h3>1.7.4: Oct 25 1999</h3> 1933<ul> 1934 <li>Lots of HTML improvement</li> 1935 <li>Fixed some errors when saving both XML and HTML</li> 1936 <li>More examples, the regression tests should now look clean</li> 1937 <li>Fixed a bug with contiguous charref</li> 1938</ul> 1939 1940<h3>1.7.3: Sep 29 1999</h3> 1941<ul> 1942 <li>portability problems fixed</li> 1943 <li>snprintf was used unconditionally, leading to link problems on system 1944 were it's not available, fixed</li> 1945</ul> 1946 1947<h3>1.7.1: Sep 24 1999</h3> 1948<ul> 1949 <li>The basic type for strings manipulated by libxml has been renamed in 1950 1.7.1 from <strong>CHAR</strong> to <strong>xmlChar</strong>. The reason 1951 is that CHAR was conflicting with a predefined type on Windows. However 1952 on non WIN32 environment, compatibility is provided by the way of a 1953 <strong>#define </strong>.</li> 1954 <li>Changed another error : the use of a structure field called errno, and 1955 leading to troubles on platforms where it's a macro</li> 1956</ul> 1957 1958<h3>1.7.0: Sep 23 1999</h3> 1959<ul> 1960 <li>Added the ability to fetch remote DTD or parsed entities, see the <a 1961 href="html/libxml-nanohttp.html">nanohttp</a> module.</li> 1962 <li>Added an errno to report errors by another mean than a simple printf 1963 like callback</li> 1964 <li>Finished ID/IDREF support and checking when validation</li> 1965 <li>Serious memory leaks fixed (there is now a <a 1966 href="html/libxml-xmlmemory.html">memory wrapper</a> module)</li> 1967 <li>Improvement of <a href="http://www.w3.org/TR/xpath">XPath</a> 1968 implementation</li> 1969 <li>Added an HTML parser front-end</li> 1970</ul> 1971 1972<h2><a name="XML">XML</a></h2> 1973 1974<p><a href="http://www.w3.org/TR/REC-xml">XML is a standard</a> for 1975markup-based structured documents. Here is <a name="example">an example XML 1976document</a>:</p> 1977<pre><?xml version="1.0"?> 1978<EXAMPLE prop1="gnome is great" prop2="&amp; linux too"> 1979 <head> 1980 <title>Welcome to Gnome</title> 1981 </head> 1982 <chapter> 1983 <title>The Linux adventure</title> 1984 <p>bla bla bla ...</p> 1985 <image href="linus.gif"/> 1986 <p>...</p> 1987 </chapter> 1988</EXAMPLE></pre> 1989 1990<p>The first line specifies that it is an XML document and gives useful 1991information about its encoding. Then the rest of the document is a text 1992format whose structure is specified by tags between brackets. <strong>Each 1993tag opened has to be closed</strong>. XML is pedantic about this. However, if 1994a tag is empty (no content), a single tag can serve as both the opening and 1995closing tag if it ends with <code>/></code> rather than with 1996<code>></code>. Note that, for example, the image tag has no content (just 1997an attribute) and is closed by ending the tag with <code>/></code>.</p> 1998 1999<p>XML can be applied successfully to a wide range of tasks, ranging from 2000long term structured document maintenance (where it follows the steps of 2001SGML) to simple data encoding mechanisms like configuration file formatting 2002(glade), spreadsheets (gnumeric), or even shorter lived documents such as 2003WebDAV where it is used to encode remote calls between a client and a 2004server.</p> 2005 2006<h2><a name="XSLT">XSLT</a></h2> 2007 2008<p>Check <a href="http://xmlsoft.org/XSLT">the separate libxslt page</a></p> 2009 2010<p><a href="http://www.w3.org/TR/xslt">XSL Transformations</a>, is a 2011language for transforming XML documents into other XML documents (or 2012HTML/textual output).</p> 2013 2014<p>A separate library called libxslt is available implementing XSLT-1.0 for 2015libxml2. This module "libxslt" too can be found in the Gnome CVS base.</p> 2016 2017<p>You can check the <a 2018href="http://cvs.gnome.org/lxr/source/libxslt/FEATURES">features</a> 2019supported and the progresses on the <a 2020href="http://cvs.gnome.org/lxr/source/libxslt/ChangeLog" 2021name="Changelog">Changelog</a>.</p> 2022 2023<h2><a name="Python">Python and bindings</a></h2> 2024 2025<p>There are a number of language bindings and wrappers available for 2026libxml2, the list below is not exhaustive. Please contact the <a 2027href="http://mail.gnome.org/mailman/listinfo/xml-bindings">xml-bindings@gnome.org</a> 2028(<a href="http://mail.gnome.org/archives/xml-bindings/">archives</a>) in 2029order to get updates to this list or to discuss the specific topic of libxml2 2030or libxslt wrappers or bindings:</p> 2031<ul> 2032 <li><a href="http://libxmlplusplus.sourceforge.net/">Libxml++</a> seems the 2033 most up-to-date C++ bindings for libxml2, check the <a 2034 href="http://libxmlplusplus.sourceforge.net/reference/html/hierarchy.html">documentation</a> 2035 and the <a 2036 href="http://cvs.sourceforge.net/cgi-bin/viewcvs.cgi/libxmlplusplus/libxml%2b%2b/examples/">examples</a>.</li> 2037 <li>There is another <a href="http://libgdome-cpp.berlios.de/">C++ wrapper 2038 based on the gdome2 bindings</a> maintained by Tobias Peters.</li> 2039 <li>and a third C++ wrapper by Peter Jones <pjones@pmade.org> 2040 <p>Website: <a 2041 href="http://pmade.org/pjones/software/xmlwrapp/">http://pmade.org/pjones/software/xmlwrapp/</a></p> 2042 </li> 2043 <li><a 2044 href="http://mail.gnome.org/archives/xml/2001-March/msg00014.html">Matt 2045 Sergeant</a> developed <a 2046 href="http://axkit.org/download/">XML::LibXSLT</a>, a Perl wrapper for 2047 libxml2/libxslt as part of the <a href="http://axkit.com/">AxKit XML 2048 application server</a>.</li> 2049 <li>If you're interested into scripting XML processing, have a look at <a 2050 href="http://xsh.sourceforge.net/">XSH</a> an XML editing shell based on 2051 Libxml2 Perl bindings.</li> 2052 <li><a href="mailto:dkuhlman@cutter.rexx.com">Dave Kuhlman</a> provides an 2053 earlier version of the libxml/libxslt <a 2054 href="http://www.rexx.com/~dkuhlman">wrappers for Python</a>.</li> 2055 <li>Gopal.V and Peter Minten develop <a 2056 href="http://savannah.gnu.org/projects/libxmlsharp">libxml#</a>, a set of 2057 C# libxml2 bindings.</li> 2058 <li>Petr Kozelka provides <a 2059 href="http://sourceforge.net/projects/libxml2-pas">Pascal units to glue 2060 libxml2</a> with Kylix, Delphi and other Pascal compilers.</li> 2061 <li>Uwe Fechner also provides <a 2062 href="http://sourceforge.net/projects/idom2-pas/">idom2</a>, a DOM2 2063 implementation for Kylix2/D5/D6 from Borland.</li> 2064 <li>Wai-Sun "Squidster" Chia provides <a 2065 href="http://www.rubycolor.org/arc/redist/">bindings for Ruby</a> and 2066 libxml2 bindings are also available in Ruby through the <a 2067 href="http://libgdome-ruby.berlios.de/">libgdome-ruby</a> module 2068 maintained by Tobias Peters.</li> 2069 <li>Steve Ball and contributors maintains <a 2070 href="http://tclxml.sourceforge.net/">libxml2 and libxslt bindings for 2071 Tcl</a>.</li> 2072 <li>There is support for libxml2 in the DOM module of PHP.</li> 2073 <li><a href="http://savannah.gnu.org/projects/classpathx/">LibxmlJ</a> is 2074 an effort to create a 100% JAXP-compatible Java wrapper for libxml2 and 2075 libxslt as part of GNU ClasspathX project.</li> 2076 <li>Patrick McPhee provides Rexx bindings fof libxml2 and libxslt, look for 2077 <a href="http://www.interlog.com/~ptjm/software.html">RexxXML</a>.</li> 2078</ul> 2079 2080<p>The distribution includes a set of Python bindings, which are guaranteed 2081to be maintained as part of the library in the future, though the Python 2082interface have not yet reached the completeness of the C API.</p> 2083 2084<p><a href="mailto:stephane.bidoul@softwareag.com">St�phane Bidoul</a> 2085maintains <a href="http://users.skynet.be/sbi/libxml-python/">a Windows port 2086of the Python bindings</a>.</p> 2087 2088<p>Note to people interested in building bindings, the API is formalized as 2089<a href="libxml2-api.xml">an XML API description file</a> which allows to 2090automate a large part of the Python bindings, this includes function 2091descriptions, enums, structures, typedefs, etc... The Python script used to 2092build the bindings is python/generator.py in the source distribution.</p> 2093 2094<p>To install the Python bindings there are 2 options:</p> 2095<ul> 2096 <li>If you use an RPM based distribution, simply install the <a 2097 href="http://rpmfind.net/linux/rpm2html/search.php?query=libxml2-python">libxml2-python 2098 RPM</a> (and if needed the <a 2099 href="http://rpmfind.net/linux/rpm2html/search.php?query=libxslt-python">libxslt-python 2100 RPM</a>).</li> 2101 <li>Otherwise use the <a href="ftp://xmlsoft.org/python/">libxml2-python 2102 module distribution</a> corresponding to your installed version of 2103 libxml2 and libxslt. Note that to install it you will need both libxml2 2104 and libxslt installed and run "python setup.py build install" in the 2105 module tree.</li> 2106</ul> 2107 2108<p>The distribution includes a set of examples and regression tests for the 2109python bindings in the <code>python/tests</code> directory. Here are some 2110excerpts from those tests:</p> 2111 2112<h3>tst.py:</h3> 2113 2114<p>This is a basic test of the file interface and DOM navigation:</p> 2115<pre>import libxml2, sys 2116 2117doc = libxml2.parseFile("tst.xml") 2118if doc.name != "tst.xml": 2119 print "doc.name failed" 2120 sys.exit(1) 2121root = doc.children 2122if root.name != "doc": 2123 print "root.name failed" 2124 sys.exit(1) 2125child = root.children 2126if child.name != "foo": 2127 print "child.name failed" 2128 sys.exit(1) 2129doc.freeDoc()</pre> 2130 2131<p>The Python module is called libxml2; parseFile is the equivalent of 2132xmlParseFile (most of the bindings are automatically generated, and the xml 2133prefix is removed and the casing convention are kept). All node seen at the 2134binding level share the same subset of accessors:</p> 2135<ul> 2136 <li><code>name</code> : returns the node name</li> 2137 <li><code>type</code> : returns a string indicating the node type</li> 2138 <li><code>content</code> : returns the content of the node, it is based on 2139 xmlNodeGetContent() and hence is recursive.</li> 2140 <li><code>parent</code> , <code>children</code>, <code>last</code>, 2141 <code>next</code>, <code>prev</code>, <code>doc</code>, 2142 <code>properties</code>: pointing to the associated element in the tree, 2143 those may return None in case no such link exists.</li> 2144</ul> 2145 2146<p>Also note the need to explicitly deallocate documents with freeDoc() . 2147Reference counting for libxml2 trees would need quite a lot of work to 2148function properly, and rather than risk memory leaks if not implemented 2149correctly it sounds safer to have an explicit function to free a tree. The 2150wrapper python objects like doc, root or child are them automatically garbage 2151collected.</p> 2152 2153<h3>validate.py:</h3> 2154 2155<p>This test check the validation interfaces and redirection of error 2156messages:</p> 2157<pre>import libxml2 2158 2159#deactivate error messages from the validation 2160def noerr(ctx, str): 2161 pass 2162 2163libxml2.registerErrorHandler(noerr, None) 2164 2165ctxt = libxml2.createFileParserCtxt("invalid.xml") 2166ctxt.validate(1) 2167ctxt.parseDocument() 2168doc = ctxt.doc() 2169valid = ctxt.isValid() 2170doc.freeDoc() 2171if valid != 0: 2172 print "validity check failed"</pre> 2173 2174<p>The first thing to notice is the call to registerErrorHandler(), it 2175defines a new error handler global to the library. It is used to avoid seeing 2176the error messages when trying to validate the invalid document.</p> 2177 2178<p>The main interest of that test is the creation of a parser context with 2179createFileParserCtxt() and how the behaviour can be changed before calling 2180parseDocument() . Similarly the informations resulting from the parsing phase 2181are also available using context methods.</p> 2182 2183<p>Contexts like nodes are defined as class and the libxml2 wrappers maps the 2184C function interfaces in terms of objects method as much as possible. The 2185best to get a complete view of what methods are supported is to look at the 2186libxml2.py module containing all the wrappers.</p> 2187 2188<h3>push.py:</h3> 2189 2190<p>This test show how to activate the push parser interface:</p> 2191<pre>import libxml2 2192 2193ctxt = libxml2.createPushParser(None, "<foo", 4, "test.xml") 2194ctxt.parseChunk("/>", 2, 1) 2195doc = ctxt.doc() 2196 2197doc.freeDoc()</pre> 2198 2199<p>The context is created with a special call based on the 2200xmlCreatePushParser() from the C library. The first argument is an optional 2201SAX callback object, then the initial set of data, the length and the name of 2202the resource in case URI-References need to be computed by the parser.</p> 2203 2204<p>Then the data are pushed using the parseChunk() method, the last call 2205setting the third argument terminate to 1.</p> 2206 2207<h3>pushSAX.py:</h3> 2208 2209<p>this test show the use of the event based parsing interfaces. In this case 2210the parser does not build a document, but provides callback information as 2211the parser makes progresses analyzing the data being provided:</p> 2212<pre>import libxml2 2213log = "" 2214 2215class callback: 2216 def startDocument(self): 2217 global log 2218 log = log + "startDocument:" 2219 2220 def endDocument(self): 2221 global log 2222 log = log + "endDocument:" 2223 2224 def startElement(self, tag, attrs): 2225 global log 2226 log = log + "startElement %s %s:" % (tag, attrs) 2227 2228 def endElement(self, tag): 2229 global log 2230 log = log + "endElement %s:" % (tag) 2231 2232 def characters(self, data): 2233 global log 2234 log = log + "characters: %s:" % (data) 2235 2236 def warning(self, msg): 2237 global log 2238 log = log + "warning: %s:" % (msg) 2239 2240 def error(self, msg): 2241 global log 2242 log = log + "error: %s:" % (msg) 2243 2244 def fatalError(self, msg): 2245 global log 2246 log = log + "fatalError: %s:" % (msg) 2247 2248handler = callback() 2249 2250ctxt = libxml2.createPushParser(handler, "<foo", 4, "test.xml") 2251chunk = " url='tst'>b" 2252ctxt.parseChunk(chunk, len(chunk), 0) 2253chunk = "ar</foo>" 2254ctxt.parseChunk(chunk, len(chunk), 1) 2255 2256reference = "startDocument:startElement foo {'url': 'tst'}:" + \ 2257 "characters: bar:endElement foo:endDocument:" 2258if log != reference: 2259 print "Error got: %s" % log 2260 print "Expected: %s" % reference</pre> 2261 2262<p>The key object in that test is the handler, it provides a number of entry 2263points which can be called by the parser as it makes progresses to indicate 2264the information set obtained. The full set of callback is larger than what 2265the callback class in that specific example implements (see the SAX 2266definition for a complete list). The wrapper will only call those supplied by 2267the object when activated. The startElement receives the names of the element 2268and a dictionary containing the attributes carried by this element.</p> 2269 2270<p>Also note that the reference string generated from the callback shows a 2271single character call even though the string "bar" is passed to the parser 2272from 2 different call to parseChunk()</p> 2273 2274<h3>xpath.py:</h3> 2275 2276<p>This is a basic test of XPath wrappers support</p> 2277<pre>import libxml2 2278 2279doc = libxml2.parseFile("tst.xml") 2280ctxt = doc.xpathNewContext() 2281res = ctxt.xpathEval("//*") 2282if len(res) != 2: 2283 print "xpath query: wrong node set size" 2284 sys.exit(1) 2285if res[0].name != "doc" or res[1].name != "foo": 2286 print "xpath query: wrong node set value" 2287 sys.exit(1) 2288doc.freeDoc() 2289ctxt.xpathFreeContext()</pre> 2290 2291<p>This test parses a file, then create an XPath context to evaluate XPath 2292expression on it. The xpathEval() method execute an XPath query and returns 2293the result mapped in a Python way. String and numbers are natively converted, 2294and node sets are returned as a tuple of libxml2 Python nodes wrappers. Like 2295the document, the XPath context need to be freed explicitly, also not that 2296the result of the XPath query may point back to the document tree and hence 2297the document must be freed after the result of the query is used.</p> 2298 2299<h3>xpathext.py:</h3> 2300 2301<p>This test shows how to extend the XPath engine with functions written in 2302python:</p> 2303<pre>import libxml2 2304 2305def foo(ctx, x): 2306 return x + 1 2307 2308doc = libxml2.parseFile("tst.xml") 2309ctxt = doc.xpathNewContext() 2310libxml2.registerXPathFunction(ctxt._o, "foo", None, foo) 2311res = ctxt.xpathEval("foo(1)") 2312if res != 2: 2313 print "xpath extension failure" 2314doc.freeDoc() 2315ctxt.xpathFreeContext()</pre> 2316 2317<p>Note how the extension function is registered with the context (but that 2318part is not yet finalized, this may change slightly in the future).</p> 2319 2320<h3>tstxpath.py:</h3> 2321 2322<p>This test is similar to the previous one but shows how the extension 2323function can access the XPath evaluation context:</p> 2324<pre>def foo(ctx, x): 2325 global called 2326 2327 # 2328 # test that access to the XPath evaluation contexts 2329 # 2330 pctxt = libxml2.xpathParserContext(_obj=ctx) 2331 ctxt = pctxt.context() 2332 called = ctxt.function() 2333 return x + 1</pre> 2334 2335<p>All the interfaces around the XPath parser(or rather evaluation) context 2336are not finalized, but it should be sufficient to do contextual work at the 2337evaluation point.</p> 2338 2339<h3>Memory debugging:</h3> 2340 2341<p>last but not least, all tests starts with the following prologue:</p> 2342<pre>#memory debug specific 2343libxml2.debugMemory(1)</pre> 2344 2345<p>and ends with the following epilogue:</p> 2346<pre>#memory debug specific 2347libxml2.cleanupParser() 2348if libxml2.debugMemory(1) == 0: 2349 print "OK" 2350else: 2351 print "Memory leak %d bytes" % (libxml2.debugMemory(1)) 2352 libxml2.dumpMemory()</pre> 2353 2354<p>Those activate the memory debugging interface of libxml2 where all 2355allocated block in the library are tracked. The prologue then cleans up the 2356library state and checks that all allocated memory has been freed. If not it 2357calls dumpMemory() which saves that list in a <code>.memdump</code> file.</p> 2358 2359<h2><a name="architecture">libxml2 architecture</a></h2> 2360 2361<p>Libxml2 is made of multiple components; some of them are optional, and 2362most of the block interfaces are public. The main components are:</p> 2363<ul> 2364 <li>an Input/Output layer</li> 2365 <li>FTP and HTTP client layers (optional)</li> 2366 <li>an Internationalization layer managing the encodings support</li> 2367 <li>a URI module</li> 2368 <li>the XML parser and its basic SAX interface</li> 2369 <li>an HTML parser using the same SAX interface (optional)</li> 2370 <li>a SAX tree module to build an in-memory DOM representation</li> 2371 <li>a tree module to manipulate the DOM representation</li> 2372 <li>a validation module using the DOM representation (optional)</li> 2373 <li>an XPath module for global lookup in a DOM representation 2374 (optional)</li> 2375 <li>a debug module (optional)</li> 2376</ul> 2377 2378<p>Graphically this gives the following:</p> 2379 2380<p><img src="libxml.gif" alt="a graphical view of the various"></p> 2381 2382<p></p> 2383 2384<h2><a name="tree">The tree output</a></h2> 2385 2386<p>The parser returns a tree built during the document analysis. The value 2387returned is an <strong>xmlDocPtr</strong> (i.e., a pointer to an 2388<strong>xmlDoc</strong> structure). This structure contains information such 2389as the file name, the document type, and a <strong>children</strong> pointer 2390which is the root of the document (or more exactly the first child under the 2391root which is the document). The tree is made of <strong>xmlNode</strong>s, 2392chained in double-linked lists of siblings and with a children<->parent 2393relationship. An xmlNode can also carry properties (a chain of xmlAttr 2394structures). An attribute may have a value which is a list of TEXT or 2395ENTITY_REF nodes.</p> 2396 2397<p>Here is an example (erroneous with respect to the XML spec since there 2398should be only one ELEMENT under the root):</p> 2399 2400<p><img src="structure.gif" alt=" structure.gif "></p> 2401 2402<p>In the source package there is a small program (not installed by default) 2403called <strong>xmllint</strong> which parses XML files given as argument and 2404prints them back as parsed. This is useful for detecting errors both in XML 2405code and in the XML parser itself. It has an option <strong>--debug</strong> 2406which prints the actual in-memory structure of the document; here is the 2407result with the <a href="#example">example</a> given before:</p> 2408<pre>DOCUMENT 2409version=1.0 2410standalone=true 2411 ELEMENT EXAMPLE 2412 ATTRIBUTE prop1 2413 TEXT 2414 content=gnome is great 2415 ATTRIBUTE prop2 2416 ENTITY_REF 2417 TEXT 2418 content= linux too 2419 ELEMENT head 2420 ELEMENT title 2421 TEXT 2422 content=Welcome to Gnome 2423 ELEMENT chapter 2424 ELEMENT title 2425 TEXT 2426 content=The Linux adventure 2427 ELEMENT p 2428 TEXT 2429 content=bla bla bla ... 2430 ELEMENT image 2431 ATTRIBUTE href 2432 TEXT 2433 content=linus.gif 2434 ELEMENT p 2435 TEXT 2436 content=...</pre> 2437 2438<p>This should be useful for learning the internal representation model.</p> 2439 2440<h2><a name="interface">The SAX interface</a></h2> 2441 2442<p>Sometimes the DOM tree output is just too large to fit reasonably into 2443memory. In that case (and if you don't expect to save back the XML document 2444loaded using libxml), it's better to use the SAX interface of libxml. SAX is 2445a <strong>callback-based interface</strong> to the parser. Before parsing, 2446the application layer registers a customized set of callbacks which are 2447called by the library as it progresses through the XML input.</p> 2448 2449<p>To get more detailed step-by-step guidance on using the SAX interface of 2450libxml, see the <a 2451href="http://www.daa.com.au/~james/gnome/xml-sax/xml-sax.html">nice 2452documentation</a>.written by <a href="mailto:james@daa.com.au">James 2453Henstridge</a>.</p> 2454 2455<p>You can debug the SAX behaviour by using the <strong>testSAX</strong> 2456program located in the gnome-xml module (it's usually not shipped in the 2457binary packages of libxml, but you can find it in the tar source 2458distribution). Here is the sequence of callbacks that would be reported by 2459testSAX when parsing the example XML document shown earlier:</p> 2460<pre>SAX.setDocumentLocator() 2461SAX.startDocument() 2462SAX.getEntity(amp) 2463SAX.startElement(EXAMPLE, prop1='gnome is great', prop2='&amp; linux too') 2464SAX.characters( , 3) 2465SAX.startElement(head) 2466SAX.characters( , 4) 2467SAX.startElement(title) 2468SAX.characters(Welcome to Gnome, 16) 2469SAX.endElement(title) 2470SAX.characters( , 3) 2471SAX.endElement(head) 2472SAX.characters( , 3) 2473SAX.startElement(chapter) 2474SAX.characters( , 4) 2475SAX.startElement(title) 2476SAX.characters(The Linux adventure, 19) 2477SAX.endElement(title) 2478SAX.characters( , 4) 2479SAX.startElement(p) 2480SAX.characters(bla bla bla ..., 15) 2481SAX.endElement(p) 2482SAX.characters( , 4) 2483SAX.startElement(image, href='linus.gif') 2484SAX.endElement(image) 2485SAX.characters( , 4) 2486SAX.startElement(p) 2487SAX.characters(..., 3) 2488SAX.endElement(p) 2489SAX.characters( , 3) 2490SAX.endElement(chapter) 2491SAX.characters( , 1) 2492SAX.endElement(EXAMPLE) 2493SAX.endDocument()</pre> 2494 2495<p>Most of the other interfaces of libxml2 are based on the DOM tree-building 2496facility, so nearly everything up to the end of this document presupposes the 2497use of the standard DOM tree build. Note that the DOM tree itself is built by 2498a set of registered default callbacks, without internal specific 2499interface.</p> 2500 2501<h2><a name="Validation">Validation & DTDs</a></h2> 2502 2503<p>Table of Content:</p> 2504<ol> 2505 <li><a href="#General5">General overview</a></li> 2506 <li><a href="#definition">The definition</a></li> 2507 <li><a href="#Simple">Simple rules</a> 2508 <ol> 2509 <li><a href="#reference">How to reference a DTD from a document</a></li> 2510 <li><a href="#Declaring">Declaring elements</a></li> 2511 <li><a href="#Declaring1">Declaring attributes</a></li> 2512 </ol> 2513 </li> 2514 <li><a href="#Some">Some examples</a></li> 2515 <li><a href="#validate">How to validate</a></li> 2516 <li><a href="#Other">Other resources</a></li> 2517</ol> 2518 2519<h3><a name="General5">General overview</a></h3> 2520 2521<p>Well what is validation and what is a DTD ?</p> 2522 2523<p>DTD is the acronym for Document Type Definition. This is a description of 2524the content for a family of XML files. This is part of the XML 1.0 2525specification, and allows one to describe and verify that a given document 2526instance conforms to the set of rules detailing its structure and content.</p> 2527 2528<p>Validation is the process of checking a document against a DTD (more 2529generally against a set of construction rules).</p> 2530 2531<p>The validation process and building DTDs are the two most difficult parts 2532of the XML life cycle. Briefly a DTD defines all the possible elements to be 2533found within your document, what is the formal shape of your document tree 2534(by defining the allowed content of an element; either text, a regular 2535expression for the allowed list of children, or mixed content i.e. both text 2536and children). The DTD also defines the valid attributes for all elements and 2537the types of those attributes.</p> 2538 2539<h3><a name="definition1">The definition</a></h3> 2540 2541<p>The <a href="http://www.w3.org/TR/REC-xml">W3C XML Recommendation</a> (<a 2542href="http://www.xml.com/axml/axml.html">Tim Bray's annotated version of 2543Rev1</a>):</p> 2544<ul> 2545 <li><a href="http://www.w3.org/TR/REC-xml#elemdecls">Declaring 2546 elements</a></li> 2547 <li><a href="http://www.w3.org/TR/REC-xml#attdecls">Declaring 2548 attributes</a></li> 2549</ul> 2550 2551<p>(unfortunately) all this is inherited from the SGML world, the syntax is 2552ancient...</p> 2553 2554<h3><a name="Simple1">Simple rules</a></h3> 2555 2556<p>Writing DTDs can be done in many ways. The rules to build them if you need 2557something permanent or something which can evolve over time can be radically 2558different. Really complex DTDs like DocBook ones are flexible but quite 2559harder to design. I will just focus on DTDs for a formats with a fixed simple 2560structure. It is just a set of basic rules, and definitely not exhaustive nor 2561usable for complex DTD design.</p> 2562 2563<h4><a name="reference1">How to reference a DTD from a document</a>:</h4> 2564 2565<p>Assuming the top element of the document is <code>spec</code> and the dtd 2566is placed in the file <code>mydtd</code> in the subdirectory 2567<code>dtds</code> of the directory from where the document were loaded:</p> 2568 2569<p><code><!DOCTYPE spec SYSTEM "dtds/mydtd"></code></p> 2570 2571<p>Notes:</p> 2572<ul> 2573 <li>The system string is actually an URI-Reference (as defined in <a 2574 href="http://www.ietf.org/rfc/rfc2396.txt">RFC 2396</a>) so you can use a 2575 full URL string indicating the location of your DTD on the Web. This is a 2576 really good thing to do if you want others to validate your document.</li> 2577 <li>It is also possible to associate a <code>PUBLIC</code> identifier (a 2578 magic string) so that the DTD is looked up in catalogs on the client side 2579 without having to locate it on the web.</li> 2580 <li>A DTD contains a set of element and attribute declarations, but they 2581 don't define what the root of the document should be. This is explicitly 2582 told to the parser/validator as the first element of the 2583 <code>DOCTYPE</code> declaration.</li> 2584</ul> 2585 2586<h4><a name="Declaring2">Declaring elements</a>:</h4> 2587 2588<p>The following declares an element <code>spec</code>:</p> 2589 2590<p><code><!ELEMENT spec (front, body, back?)></code></p> 2591 2592<p>It also expresses that the spec element contains one <code>front</code>, 2593one <code>body</code> and one optional <code>back</code> children elements in 2594this order. The declaration of one element of the structure and its content 2595are done in a single declaration. Similarly the following declares 2596<code>div1</code> elements:</p> 2597 2598<p><code><!ELEMENT div1 (head, (p | list | note)*, div2?)></code></p> 2599 2600<p>which means div1 contains one <code>head</code> then a series of optional 2601<code>p</code>, <code>list</code>s and <code>note</code>s and then an 2602optional <code>div2</code>. And last but not least an element can contain 2603text:</p> 2604 2605<p><code><!ELEMENT b (#PCDATA)></code></p> 2606 2607<p><code>b</code> contains text or being of mixed content (text and elements 2608in no particular order):</p> 2609 2610<p><code><!ELEMENT p (#PCDATA|a|ul|b|i|em)*></code></p> 2611 2612<p><code>p </code>can contain text or <code>a</code>, <code>ul</code>, 2613<code>b</code>, <code>i </code>or <code>em</code> elements in no particular 2614order.</p> 2615 2616<h4><a name="Declaring1">Declaring attributes</a>:</h4> 2617 2618<p>Again the attributes declaration includes their content definition:</p> 2619 2620<p><code><!ATTLIST termdef name CDATA #IMPLIED></code></p> 2621 2622<p>means that the element <code>termdef</code> can have a <code>name</code> 2623attribute containing text (<code>CDATA</code>) and which is optional 2624(<code>#IMPLIED</code>). The attribute value can also be defined within a 2625set:</p> 2626 2627<p><code><!ATTLIST list type (bullets|ordered|glossary) 2628"ordered"></code></p> 2629 2630<p>means <code>list</code> element have a <code>type</code> attribute with 3 2631allowed values "bullets", "ordered" or "glossary" and which default to 2632"ordered" if the attribute is not explicitly specified.</p> 2633 2634<p>The content type of an attribute can be text (<code>CDATA</code>), 2635anchor/reference/references 2636(<code>ID</code>/<code>IDREF</code>/<code>IDREFS</code>), entity(ies) 2637(<code>ENTITY</code>/<code>ENTITIES</code>) or name(s) 2638(<code>NMTOKEN</code>/<code>NMTOKENS</code>). The following defines that a 2639<code>chapter</code> element can have an optional <code>id</code> attribute 2640of type <code>ID</code>, usable for reference from attribute of type 2641IDREF:</p> 2642 2643<p><code><!ATTLIST chapter id ID #IMPLIED></code></p> 2644 2645<p>The last value of an attribute definition can be <code>#REQUIRED 2646</code>meaning that the attribute has to be given, <code>#IMPLIED</code> 2647meaning that it is optional, or the default value (possibly prefixed by 2648<code>#FIXED</code> if it is the only allowed).</p> 2649 2650<p>Notes:</p> 2651<ul> 2652 <li>Usually the attributes pertaining to a given element are declared in a 2653 single expression, but it is just a convention adopted by a lot of DTD 2654 writers: 2655 <pre><!ATTLIST termdef 2656 id ID #REQUIRED 2657 name CDATA #IMPLIED></pre> 2658 <p>The previous construct defines both <code>id</code> and 2659 <code>name</code> attributes for the element <code>termdef</code>.</p> 2660 </li> 2661</ul> 2662 2663<h3><a name="Some1">Some examples</a></h3> 2664 2665<p>The directory <code>test/valid/dtds/</code> in the libxml2 distribution 2666contains some complex DTD examples. The example in the file 2667<code>test/valid/dia.xml</code> shows an XML file where the simple DTD is 2668directly included within the document.</p> 2669 2670<h3><a name="validate1">How to validate</a></h3> 2671 2672<p>The simplest way is to use the xmllint program included with libxml. The 2673<code>--valid</code> option turns-on validation of the files given as input. 2674For example the following validates a copy of the first revision of the XML 26751.0 specification:</p> 2676 2677<p><code>xmllint --valid --noout test/valid/REC-xml-19980210.xml</code></p> 2678 2679<p>the -- noout is used to disable output of the resulting tree.</p> 2680 2681<p>The <code>--dtdvalid dtd</code> allows validation of the document(s) 2682against a given DTD.</p> 2683 2684<p>Libxml2 exports an API to handle DTDs and validation, check the <a 2685href="http://xmlsoft.org/html/libxml-valid.html">associated 2686description</a>.</p> 2687 2688<h3><a name="Other1">Other resources</a></h3> 2689 2690<p>DTDs are as old as SGML. So there may be a number of examples on-line, I 2691will just list one for now, others pointers welcome:</p> 2692<ul> 2693 <li><a href="http://www.xml101.com:8081/dtd/">XML-101 DTD</a></li> 2694</ul> 2695 2696<p>I suggest looking at the examples found under test/valid/dtd and any of 2697the large number of books available on XML. The dia example in test/valid 2698should be both simple and complete enough to allow you to build your own.</p> 2699 2700<p></p> 2701 2702<h2><a name="Memory">Memory Management</a></h2> 2703 2704<p>Table of Content:</p> 2705<ol> 2706 <li><a href="#General3">General overview</a></li> 2707 <li><a href="#setting">Setting libxml2 set of memory routines</a></li> 2708 <li><a href="#cleanup">Cleaning up after parsing</a></li> 2709 <li><a href="#Debugging">Debugging routines</a></li> 2710 <li><a href="#General4">General memory requirements</a></li> 2711</ol> 2712 2713<h3><a name="General3">General overview</a></h3> 2714 2715<p>The module <code><a 2716href="http://xmlsoft.org/html/libxml-xmlmemory.html">xmlmemory.h</a></code> 2717provides the interfaces to the libxml2 memory system:</p> 2718<ul> 2719 <li>libxml2 does not use the libc memory allocator directly but xmlFree(), 2720 xmlMalloc() and xmlRealloc()</li> 2721 <li>those routines can be reallocated to a specific set of routine, by 2722 default the libc ones i.e. free(), malloc() and realloc()</li> 2723 <li>the xmlmemory.c module includes a set of debugging routine</li> 2724</ul> 2725 2726<h3><a name="setting">Setting libxml2 set of memory routines</a></h3> 2727 2728<p>It is sometimes useful to not use the default memory allocator, either for 2729debugging, analysis or to implement a specific behaviour on memory management 2730(like on embedded systems). Two function calls are available to do so:</p> 2731<ul> 2732 <li><a href="http://xmlsoft.org/html/libxml-xmlmemory.html">xmlMemGet 2733 ()</a> which return the current set of functions in use by the parser</li> 2734 <li><a 2735 href="http://xmlsoft.org/html/libxml-xmlmemory.html">xmlMemSetup()</a> 2736 which allow to set up a new set of memory allocation functions</li> 2737</ul> 2738 2739<p>Of course a call to xmlMemSetup() should probably be done before calling 2740any other libxml2 routines (unless you are sure your allocations routines are 2741compatibles).</p> 2742 2743<h3><a name="cleanup">Cleaning up after parsing</a></h3> 2744 2745<p>Libxml2 is not stateless, there is a few set of memory structures needing 2746allocation before the parser is fully functional (some encoding structures 2747for example). This also mean that once parsing is finished there is a tiny 2748amount of memory (a few hundred bytes) which can be recollected if you don't 2749reuse the parser immediately:</p> 2750<ul> 2751 <li><a href="http://xmlsoft.org/html/libxml-parser.html">xmlCleanupParser 2752 ()</a> is a centralized routine to free the parsing states. Note that it 2753 won't deallocate any produced tree if any (use the xmlFreeDoc() and 2754 related routines for this).</li> 2755 <li><a href="http://xmlsoft.org/html/libxml-parser.html">xmlInitParser 2756 ()</a> is the dual routine allowing to preallocate the parsing state 2757 which can be useful for example to avoid initialization reentrancy 2758 problems when using libxml2 in multithreaded applications</li> 2759</ul> 2760 2761<p>Generally xmlCleanupParser() is safe, if needed the state will be rebuild 2762at the next invocation of parser routines, but be careful of the consequences 2763in multithreaded applications.</p> 2764 2765<h3><a name="Debugging">Debugging routines</a></h3> 2766 2767<p>When configured using --with-mem-debug flag (off by default), libxml2 uses 2768a set of memory allocation debugging routines keeping track of all allocated 2769blocks and the location in the code where the routine was called. A couple of 2770other debugging routines allow to dump the memory allocated infos to a file 2771or call a specific routine when a given block number is allocated:</p> 2772<ul> 2773 <li><a 2774 href="http://xmlsoft.org/html/libxml-xmlmemory.html">xmlMallocLoc()</a> 2775 <a 2776 href="http://xmlsoft.org/html/libxml-xmlmemory.html">xmlReallocLoc()</a> 2777 and <a 2778 href="http://xmlsoft.org/html/libxml-xmlmemory.html">xmlMemStrdupLoc()</a> 2779 are the memory debugging replacement allocation routines</li> 2780 <li><a href="http://xmlsoft.org/html/libxml-xmlmemory.html">xmlMemoryDump 2781 ()</a> dumps all the informations about the allocated memory block lefts 2782 in the <code>.memdump</code> file</li> 2783</ul> 2784 2785<p>When developing libxml2 memory debug is enabled, the tests programs call 2786xmlMemoryDump () and the "make test" regression tests will check for any 2787memory leak during the full regression test sequence, this helps a lot 2788ensuring that libxml2 does not leak memory and bullet proof memory 2789allocations use (some libc implementations are known to be far too permissive 2790resulting in major portability problems!).</p> 2791 2792<p>If the .memdump reports a leak, it displays the allocation function and 2793also tries to give some informations about the content and structure of the 2794allocated blocks left. This is sufficient in most cases to find the culprit, 2795but not always. Assuming the allocation problem is reproducible, it is 2796possible to find more easily:</p> 2797<ol> 2798 <li>write down the block number xxxx not allocated</li> 2799 <li>export the environment variable XML_MEM_BREAKPOINT=xxxx , the easiest 2800 when using GDB is to simply give the command 2801 <p><code>set environment XML_MEM_BREAKPOINT xxxx</code></p> 2802 <p>before running the program.</p> 2803 </li> 2804 <li>run the program under a debugger and set a breakpoint on 2805 xmlMallocBreakpoint() a specific function called when this precise block 2806 is allocated</li> 2807 <li>when the breakpoint is reached you can then do a fine analysis of the 2808 allocation an step to see the condition resulting in the missing 2809 deallocation.</li> 2810</ol> 2811 2812<p>I used to use a commercial tool to debug libxml2 memory problems but after 2813noticing that it was not detecting memory leaks that simple mechanism was 2814used and proved extremely efficient until now. Lately I have also used <a 2815href="http://developer.kde.org/~sewardj/">valgrind</a> with quite some 2816success, it is tied to the i386 architecture since it works by emulating the 2817processor and instruction set, it is slow but extremely efficient, i.e. it 2818spot memory usage errors in a very precise way.</p> 2819 2820<h3><a name="General4">General memory requirements</a></h3> 2821 2822<p>How much libxml2 memory require ? It's hard to tell in average it depends 2823of a number of things:</p> 2824<ul> 2825 <li>the parser itself should work in a fixed amount of memory, except for 2826 information maintained about the stacks of names and entities locations. 2827 The I/O and encoding handlers will probably account for a few KBytes. 2828 This is true for both the XML and HTML parser (though the HTML parser 2829 need more state).</li> 2830 <li>If you are generating the DOM tree then memory requirements will grow 2831 nearly linear with the size of the data. In general for a balanced 2832 textual document the internal memory requirement is about 4 times the 2833 size of the UTF8 serialization of this document (example the XML-1.0 2834 recommendation is a bit more of 150KBytes and takes 650KBytes of main 2835 memory when parsed). Validation will add a amount of memory required for 2836 maintaining the external Dtd state which should be linear with the 2837 complexity of the content model defined by the Dtd</li> 2838 <li>If you need to work with fixed memory requirements or don't need the 2839 full DOM tree then using the <a href="xmlreader.html">xmlReader 2840 interface</a> is probably the best way to proceed, it still allows to 2841 validate or operate on subset of the tree if needed.</li> 2842 <li>If you don't care about the advanced features of libxml2 like 2843 validation, DOM, XPath or XPointer, don't use entities, need to work with 2844 fixed memory requirements, and try to get the fastest parsing possible 2845 then the SAX interface should be used, but it has known restrictions.</li> 2846</ul> 2847 2848<p></p> 2849 2850<h2><a name="Encodings">Encodings support</a></h2> 2851 2852<p>Table of Content:</p> 2853<ol> 2854 <li><a href="encoding.html#What">What does internationalization support 2855 mean ?</a></li> 2856 <li><a href="encoding.html#internal">The internal encoding, how and 2857 why</a></li> 2858 <li><a href="encoding.html#implemente">How is it implemented ?</a></li> 2859 <li><a href="encoding.html#Default">Default supported encodings</a></li> 2860 <li><a href="encoding.html#extend">How to extend the existing 2861 support</a></li> 2862</ol> 2863 2864<h3><a name="What">What does internationalization support mean ?</a></h3> 2865 2866<p>If you are not really familiar with Internationalization (usual shortcut 2867is I18N) , Unicode, characters and glyphs, I suggest you read a <a 2868href="http://www.tbray.org/ongoing/When/200x/2003/04/06/Unicode">presentation</a> 2869by Tim Bray on Unicode and why you should care about it.</p> 2870 2871<p>XML was designed from the start to allow the support of any character set 2872by using Unicode. Any conformant XML parser has to support the UTF-8 and 2873UTF-16 default encodings which can both express the full unicode ranges. UTF8 2874is a variable length encoding whose greatest points are to reuse the same 2875encoding for ASCII and to save space for Western encodings, but it is a bit 2876more complex to handle in practice. UTF-16 use 2 bytes per character (and 2877sometimes combines two pairs), it makes implementation easier, but looks a 2878bit overkill for Western languages encoding. Moreover the XML specification 2879allows the document to be encoded in other encodings at the condition that 2880they are clearly labeled as such. For example the following is a wellformed 2881XML document encoded in ISO-8859-1 and using accentuated letters that we 2882French like for both markup and content:</p> 2883<pre><?xml version="1.0" encoding="ISO-8859-1"?> 2884<tr�s>l�</tr�s></pre> 2885 2886<p>Having internationalization support in libxml2 means the following:</p> 2887<ul> 2888 <li>the document is properly parsed</li> 2889 <li>informations about it's encoding are saved</li> 2890 <li>it can be modified</li> 2891 <li>it can be saved in its original encoding</li> 2892 <li>it can also be saved in another encoding supported by libxml2 (for 2893 example straight UTF8 or even an ASCII form)</li> 2894</ul> 2895 2896<p>Another very important point is that the whole libxml2 API, with the 2897exception of a few routines to read with a specific encoding or save to a 2898specific encoding, is completely agnostic about the original encoding of the 2899document.</p> 2900 2901<p>It should be noted too that the HTML parser embedded in libxml2 now obey 2902the same rules too, the following document will be (as of 2.2.2) handled in 2903an internationalized fashion by libxml2 too:</p> 2904<pre><!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN" 2905 "http://www.w3.org/TR/REC-html40/loose.dtd"> 2906<html lang="fr"> 2907<head> 2908 <META HTTP-EQUIV="Content-Type" CONTENT="text/html; charset=ISO-8859-1"> 2909</head> 2910<body> 2911<p>W3C cr�e des standards pour le Web.</body> 2912</html></pre> 2913 2914<h3><a name="internal">The internal encoding, how and why</a></h3> 2915 2916<p>One of the core decisions was to force all documents to be converted to a 2917default internal encoding, and that encoding to be UTF-8, here are the 2918rationales for those choices:</p> 2919<ul> 2920 <li>keeping the native encoding in the internal form would force the libxml 2921 users (or the code associated) to be fully aware of the encoding of the 2922 original document, for examples when adding a text node to a document, 2923 the content would have to be provided in the document encoding, i.e. the 2924 client code would have to check it before hand, make sure it's conformant 2925 to the encoding, etc ... Very hard in practice, though in some specific 2926 cases this may make sense.</li> 2927 <li>the second decision was which encoding. From the XML spec only UTF8 and 2928 UTF16 really makes sense as being the two only encodings for which there 2929 is mandatory support. UCS-4 (32 bits fixed size encoding) could be 2930 considered an intelligent choice too since it's a direct Unicode mapping 2931 support. I selected UTF-8 on the basis of efficiency and compatibility 2932 with surrounding software: 2933 <ul> 2934 <li>UTF-8 while a bit more complex to convert from/to (i.e. slightly 2935 more costly to import and export CPU wise) is also far more compact 2936 than UTF-16 (and UCS-4) for a majority of the documents I see it used 2937 for right now (RPM RDF catalogs, advogato data, various configuration 2938 file formats, etc.) and the key point for today's computer 2939 architecture is efficient uses of caches. If one nearly double the 2940 memory requirement to store the same amount of data, this will trash 2941 caches (main memory/external caches/internal caches) and my take is 2942 that this harms the system far more than the CPU requirements needed 2943 for the conversion to UTF-8</li> 2944 <li>Most of libxml2 version 1 users were using it with straight ASCII 2945 most of the time, doing the conversion with an internal encoding 2946 requiring all their code to be rewritten was a serious show-stopper 2947 for using UTF-16 or UCS-4.</li> 2948 <li>UTF-8 is being used as the de-facto internal encoding standard for 2949 related code like the <a href="http://www.pango.org/">pango</a> 2950 upcoming Gnome text widget, and a lot of Unix code (yet another place 2951 where Unix programmer base takes a different approach from Microsoft 2952 - they are using UTF-16)</li> 2953 </ul> 2954 </li> 2955</ul> 2956 2957<p>What does this mean in practice for the libxml2 user:</p> 2958<ul> 2959 <li>xmlChar, the libxml2 data type is a byte, those bytes must be assembled 2960 as UTF-8 valid strings. The proper way to terminate an xmlChar * string 2961 is simply to append 0 byte, as usual.</li> 2962 <li>One just need to make sure that when using chars outside the ASCII set, 2963 the values has been properly converted to UTF-8</li> 2964</ul> 2965 2966<h3><a name="implemente">How is it implemented ?</a></h3> 2967 2968<p>Let's describe how all this works within libxml, basically the I18N 2969(internationalization) support get triggered only during I/O operation, i.e. 2970when reading a document or saving one. Let's look first at the reading 2971sequence:</p> 2972<ol> 2973 <li>when a document is processed, we usually don't know the encoding, a 2974 simple heuristic allows to detect UTF-16 and UCS-4 from encodings where 2975 the ASCII range (0-0x7F) maps with ASCII</li> 2976 <li>the xml declaration if available is parsed, including the encoding 2977 declaration. At that point, if the autodetected encoding is different 2978 from the one declared a call to xmlSwitchEncoding() is issued.</li> 2979 <li>If there is no encoding declaration, then the input has to be in either 2980 UTF-8 or UTF-16, if it is not then at some point when processing the 2981 input, the converter/checker of UTF-8 form will raise an encoding error. 2982 You may end-up with a garbled document, or no document at all ! Example: 2983 <pre>~/XML -> /xmllint err.xml 2984err.xml:1: error: Input is not proper UTF-8, indicate encoding ! 2985<tr�s>l�</tr�s> 2986 ^ 2987err.xml:1: error: Bytes: 0xE8 0x73 0x3E 0x6C 2988<tr�s>l�</tr�s> 2989 ^</pre> 2990 </li> 2991 <li>xmlSwitchEncoding() does an encoding name lookup, canonicalize it, and 2992 then search the default registered encoding converters for that encoding. 2993 If it's not within the default set and iconv() support has been compiled 2994 it, it will ask iconv for such an encoder. If this fails then the parser 2995 will report an error and stops processing: 2996 <pre>~/XML -> /xmllint err2.xml 2997err2.xml:1: error: Unsupported encoding UnsupportedEnc 2998<?xml version="1.0" encoding="UnsupportedEnc"?> 2999 ^</pre> 3000 </li> 3001 <li>From that point the encoder processes progressively the input (it is 3002 plugged as a front-end to the I/O module) for that entity. It captures 3003 and converts on-the-fly the document to be parsed to UTF-8. The parser 3004 itself just does UTF-8 checking of this input and process it 3005 transparently. The only difference is that the encoding information has 3006 been added to the parsing context (more precisely to the input 3007 corresponding to this entity).</li> 3008 <li>The result (when using DOM) is an internal form completely in UTF-8 3009 with just an encoding information on the document node.</li> 3010</ol> 3011 3012<p>Ok then what happens when saving the document (assuming you 3013collected/built an xmlDoc DOM like structure) ? It depends on the function 3014called, xmlSaveFile() will just try to save in the original encoding, while 3015xmlSaveFileTo() and xmlSaveFileEnc() can optionally save to a given 3016encoding:</p> 3017<ol> 3018 <li>if no encoding is given, libxml2 will look for an encoding value 3019 associated to the document and if it exists will try to save to that 3020 encoding, 3021 <p>otherwise everything is written in the internal form, i.e. UTF-8</p> 3022 </li> 3023 <li>so if an encoding was specified, either at the API level or on the 3024 document, libxml2 will again canonicalize the encoding name, lookup for a 3025 converter in the registered set or through iconv. If not found the 3026 function will return an error code</li> 3027 <li>the converter is placed before the I/O buffer layer, as another kind of 3028 buffer, then libxml2 will simply push the UTF-8 serialization to through 3029 that buffer, which will then progressively be converted and pushed onto 3030 the I/O layer.</li> 3031 <li>It is possible that the converter code fails on some input, for example 3032 trying to push an UTF-8 encoded Chinese character through the UTF-8 to 3033 ISO-8859-1 converter won't work. Since the encoders are progressive they 3034 will just report the error and the number of bytes converted, at that 3035 point libxml2 will decode the offending character, remove it from the 3036 buffer and replace it with the associated charRef encoding &#123; and 3037 resume the conversion. This guarantees that any document will be saved 3038 without losses (except for markup names where this is not legal, this is 3039 a problem in the current version, in practice avoid using non-ascii 3040 characters for tag or attribute names). A special "ascii" encoding name 3041 is used to save documents to a pure ascii form can be used when 3042 portability is really crucial</li> 3043</ol> 3044 3045<p>Here are a few examples based on the same test document:</p> 3046<pre>~/XML -> /xmllint isolat1 3047<?xml version="1.0" encoding="ISO-8859-1"?> 3048<tr�s>l�</tr�s> 3049~/XML -> /xmllint --encode UTF-8 isolat1 3050<?xml version="1.0" encoding="UTF-8"?> 3051<très>l� �</très> 3052~/XML -> </pre> 3053 3054<p>The same processing is applied (and reuse most of the code) for HTML I18N 3055processing. Looking up and modifying the content encoding is a bit more 3056difficult since it is located in a <meta> tag under the <head>, 3057so a couple of functions htmlGetMetaEncoding() and htmlSetMetaEncoding() have 3058been provided. The parser also attempts to switch encoding on the fly when 3059detecting such a tag on input. Except for that the processing is the same 3060(and again reuses the same code).</p> 3061 3062<h3><a name="Default">Default supported encodings</a></h3> 3063 3064<p>libxml2 has a set of default converters for the following encodings 3065(located in encoding.c):</p> 3066<ol> 3067 <li>UTF-8 is supported by default (null handlers)</li> 3068 <li>UTF-16, both little and big endian</li> 3069 <li>ISO-Latin-1 (ISO-8859-1) covering most western languages</li> 3070 <li>ASCII, useful mostly for saving</li> 3071 <li>HTML, a specific handler for the conversion of UTF-8 to ASCII with HTML 3072 predefined entities like &copy; for the Copyright sign.</li> 3073</ol> 3074 3075<p>More over when compiled on an Unix platform with iconv support the full 3076set of encodings supported by iconv can be instantly be used by libxml. On a 3077linux machine with glibc-2.1 the list of supported encodings and aliases fill 30783 full pages, and include UCS-4, the full set of ISO-Latin encodings, and the 3079various Japanese ones.</p> 3080 3081<h4>Encoding aliases</h4> 3082 3083<p>From 2.2.3, libxml2 has support to register encoding names aliases. The 3084goal is to be able to parse document whose encoding is supported but where 3085the name differs (for example from the default set of names accepted by 3086iconv). The following functions allow to register and handle new aliases for 3087existing encodings. Once registered libxml2 will automatically lookup the 3088aliases when handling a document:</p> 3089<ul> 3090 <li>int xmlAddEncodingAlias(const char *name, const char *alias);</li> 3091 <li>int xmlDelEncodingAlias(const char *alias);</li> 3092 <li>const char * xmlGetEncodingAlias(const char *alias);</li> 3093 <li>void xmlCleanupEncodingAliases(void);</li> 3094</ul> 3095 3096<h3><a name="extend">How to extend the existing support</a></h3> 3097 3098<p>Well adding support for new encoding, or overriding one of the encoders 3099(assuming it is buggy) should not be hard, just write input and output 3100conversion routines to/from UTF-8, and register them using 3101xmlNewCharEncodingHandler(name, xxxToUTF8, UTF8Toxxx), and they will be 3102called automatically if the parser(s) encounter such an encoding name 3103(register it uppercase, this will help). The description of the encoders, 3104their arguments and expected return values are described in the encoding.h 3105header.</p> 3106 3107<p>A quick note on the topic of subverting the parser to use a different 3108internal encoding than UTF-8, in some case people will absolutely want to 3109keep the internal encoding different, I think it's still possible (but the 3110encoding must be compliant with ASCII on the same subrange) though I didn't 3111tried it. The key is to override the default conversion routines (by 3112registering null encoders/decoders for your charsets), and bypass the UTF-8 3113checking of the parser by setting the parser context charset 3114(ctxt->charset) to something different than XML_CHAR_ENCODING_UTF8, but 3115there is no guarantee that this will work. You may also have some troubles 3116saving back.</p> 3117 3118<p>Basically proper I18N support is important, this requires at least 3119libxml-2.0.0, but a lot of features and corrections are really available only 3120starting 2.2.</p> 3121 3122<h2><a name="IO">I/O Interfaces</a></h2> 3123 3124<p>Table of Content:</p> 3125<ol> 3126 <li><a href="#General1">General overview</a></li> 3127 <li><a href="#basic">The basic buffer type</a></li> 3128 <li><a href="#Input">Input I/O handlers</a></li> 3129 <li><a href="#Output">Output I/O handlers</a></li> 3130 <li><a href="#entities">The entities loader</a></li> 3131 <li><a href="#Example2">Example of customized I/O</a></li> 3132</ol> 3133 3134<h3><a name="General1">General overview</a></h3> 3135 3136<p>The module <code><a 3137href="http://xmlsoft.org/html/libxml-xmlio.html">xmlIO.h</a></code> provides 3138the interfaces to the libxml2 I/O system. This consists of 4 main parts:</p> 3139<ul> 3140 <li>Entities loader, this is a routine which tries to fetch the entities 3141 (files) based on their PUBLIC and SYSTEM identifiers. The default loader 3142 don't look at the public identifier since libxml2 do not maintain a 3143 catalog. You can redefine you own entity loader by using 3144 <code>xmlGetExternalEntityLoader()</code> and 3145 <code>xmlSetExternalEntityLoader()</code>. <a href="#entities">Check the 3146 example</a>.</li> 3147 <li>Input I/O buffers which are a commodity structure used by the parser(s) 3148 input layer to handle fetching the informations to feed the parser. This 3149 provides buffering and is also a placeholder where the encoding 3150 converters to UTF8 are piggy-backed.</li> 3151 <li>Output I/O buffers are similar to the Input ones and fulfill similar 3152 task but when generating a serialization from a tree.</li> 3153 <li>A mechanism to register sets of I/O callbacks and associate them with 3154 specific naming schemes like the protocol part of the URIs. 3155 <p>This affect the default I/O operations and allows to use specific I/O 3156 handlers for certain names.</p> 3157 </li> 3158</ul> 3159 3160<p>The general mechanism used when loading http://rpmfind.net/xml.html for 3161example in the HTML parser is the following:</p> 3162<ol> 3163 <li>The default entity loader calls <code>xmlNewInputFromFile()</code> with 3164 the parsing context and the URI string.</li> 3165 <li>the URI string is checked against the existing registered handlers 3166 using their match() callback function, if the HTTP module was compiled 3167 in, it is registered and its match() function will succeeds</li> 3168 <li>the open() function of the handler is called and if successful will 3169 return an I/O Input buffer</li> 3170 <li>the parser will the start reading from this buffer and progressively 3171 fetch information from the resource, calling the read() function of the 3172 handler until the resource is exhausted</li> 3173 <li>if an encoding change is detected it will be installed on the input 3174 buffer, providing buffering and efficient use of the conversion 3175 routines</li> 3176 <li>once the parser has finished, the close() function of the handler is 3177 called once and the Input buffer and associated resources are 3178 deallocated.</li> 3179</ol> 3180 3181<p>The user defined callbacks are checked first to allow overriding of the 3182default libxml2 I/O routines.</p> 3183 3184<h3><a name="basic">The basic buffer type</a></h3> 3185 3186<p>All the buffer manipulation handling is done using the 3187<code>xmlBuffer</code> type define in <code><a 3188href="http://xmlsoft.org/html/libxml-tree.html">tree.h</a> </code>which is a 3189resizable memory buffer. The buffer allocation strategy can be selected to be 3190either best-fit or use an exponential doubling one (CPU vs. memory use 3191trade-off). The values are <code>XML_BUFFER_ALLOC_EXACT</code> and 3192<code>XML_BUFFER_ALLOC_DOUBLEIT</code>, and can be set individually or on a 3193system wide basis using <code>xmlBufferSetAllocationScheme()</code>. A number 3194of functions allows to manipulate buffers with names starting with the 3195<code>xmlBuffer...</code> prefix.</p> 3196 3197<h3><a name="Input">Input I/O handlers</a></h3> 3198 3199<p>An Input I/O handler is a simple structure 3200<code>xmlParserInputBuffer</code> containing a context associated to the 3201resource (file descriptor, or pointer to a protocol handler), the read() and 3202close() callbacks to use and an xmlBuffer. And extra xmlBuffer and a charset 3203encoding handler are also present to support charset conversion when 3204needed.</p> 3205 3206<h3><a name="Output">Output I/O handlers</a></h3> 3207 3208<p>An Output handler <code>xmlOutputBuffer</code> is completely similar to an 3209Input one except the callbacks are write() and close().</p> 3210 3211<h3><a name="entities">The entities loader</a></h3> 3212 3213<p>The entity loader resolves requests for new entities and create inputs for 3214the parser. Creating an input from a filename or an URI string is done 3215through the xmlNewInputFromFile() routine. The default entity loader do not 3216handle the PUBLIC identifier associated with an entity (if any). So it just 3217calls xmlNewInputFromFile() with the SYSTEM identifier (which is mandatory in 3218XML).</p> 3219 3220<p>If you want to hook up a catalog mechanism then you simply need to 3221override the default entity loader, here is an example:</p> 3222<pre>#include <libxml/xmlIO.h> 3223 3224xmlExternalEntityLoader defaultLoader = NULL; 3225 3226xmlParserInputPtr 3227xmlMyExternalEntityLoader(const char *URL, const char *ID, 3228 xmlParserCtxtPtr ctxt) { 3229 xmlParserInputPtr ret; 3230 const char *fileID = NULL; 3231 /* lookup for the fileID depending on ID */ 3232 3233 ret = xmlNewInputFromFile(ctxt, fileID); 3234 if (ret != NULL) 3235 return(ret); 3236 if (defaultLoader != NULL) 3237 ret = defaultLoader(URL, ID, ctxt); 3238 return(ret); 3239} 3240 3241int main(..) { 3242 ... 3243 3244 /* 3245 * Install our own entity loader 3246 */ 3247 defaultLoader = xmlGetExternalEntityLoader(); 3248 xmlSetExternalEntityLoader(xmlMyExternalEntityLoader); 3249 3250 ... 3251}</pre> 3252 3253<h3><a name="Example2">Example of customized I/O</a></h3> 3254 3255<p>This example come from <a href="http://xmlsoft.org/messages/0708.html">a 3256real use case</a>, xmlDocDump() closes the FILE * passed by the application 3257and this was a problem. The <a 3258href="http://xmlsoft.org/messages/0711.html">solution</a> was to redefine a 3259new output handler with the closing call deactivated:</p> 3260<ol> 3261 <li>First define a new I/O output allocator where the output don't close 3262 the file: 3263 <pre>xmlOutputBufferPtr 3264xmlOutputBufferCreateOwn(FILE *file, xmlCharEncodingHandlerPtr encoder) { 3265����xmlOutputBufferPtr ret; 3266���� 3267����if (xmlOutputCallbackInitialized == 0) 3268��������xmlRegisterDefaultOutputCallbacks(); 3269 3270����if (file == NULL) return(NULL); 3271����ret = xmlAllocOutputBuffer(encoder); 3272����if (ret != NULL) { 3273��������ret->context = file; 3274��������ret->writecallback = xmlFileWrite; 3275��������ret->closecallback = NULL; /* No close callback */ 3276����} 3277����return(ret); 3278} </pre> 3279 </li> 3280 <li>And then use it to save the document: 3281 <pre>FILE *f; 3282xmlOutputBufferPtr output; 3283xmlDocPtr doc; 3284int res; 3285 3286f = ... 3287doc = .... 3288 3289output = xmlOutputBufferCreateOwn(f, NULL); 3290res = xmlSaveFileTo(output, doc, NULL); 3291 </pre> 3292 </li> 3293</ol> 3294 3295<h2><a name="Catalog">Catalog support</a></h2> 3296 3297<p>Table of Content:</p> 3298<ol> 3299 <li><a href="General2">General overview</a></li> 3300 <li><a href="#definition">The definition</a></li> 3301 <li><a href="#Simple">Using catalogs</a></li> 3302 <li><a href="#Some">Some examples</a></li> 3303 <li><a href="#reference">How to tune catalog usage</a></li> 3304 <li><a href="#validate">How to debug catalog processing</a></li> 3305 <li><a href="#Declaring">How to create and maintain catalogs</a></li> 3306 <li><a href="#implemento">The implementor corner quick review of the 3307 API</a></li> 3308 <li><a href="#Other">Other resources</a></li> 3309</ol> 3310 3311<h3><a name="General2">General overview</a></h3> 3312 3313<p>What is a catalog? Basically it's a lookup mechanism used when an entity 3314(a file or a remote resource) references another entity. The catalog lookup 3315is inserted between the moment the reference is recognized by the software 3316(XML parser, stylesheet processing, or even images referenced for inclusion 3317in a rendering) and the time where loading that resource is actually 3318started.</p> 3319 3320<p>It is basically used for 3 things:</p> 3321<ul> 3322 <li>mapping from "logical" names, the public identifiers and a more 3323 concrete name usable for download (and URI). For example it can associate 3324 the logical name 3325 <p>"-//OASIS//DTD DocBook XML V4.1.2//EN"</p> 3326 <p>of the DocBook 4.1.2 XML DTD with the actual URL where it can be 3327 downloaded</p> 3328 <p>http://www.oasis-open.org/docbook/xml/4.1.2/docbookx.dtd</p> 3329 </li> 3330 <li>remapping from a given URL to another one, like an HTTP indirection 3331 saying that 3332 <p>"http://www.oasis-open.org/committes/tr.xsl"</p> 3333 <p>should really be looked at</p> 3334 <p>"http://www.oasis-open.org/committes/entity/stylesheets/base/tr.xsl"</p> 3335 </li> 3336 <li>providing a local cache mechanism allowing to load the entities 3337 associated to public identifiers or remote resources, this is a really 3338 important feature for any significant deployment of XML or SGML since it 3339 allows to avoid the aleas and delays associated to fetching remote 3340 resources.</li> 3341</ul> 3342 3343<h3><a name="definition">The definitions</a></h3> 3344 3345<p>Libxml, as of 2.4.3 implements 2 kind of catalogs:</p> 3346<ul> 3347 <li>the older SGML catalogs, the official spec is SGML Open Technical 3348 Resolution TR9401:1997, but is better understood by reading <a 3349 href="http://www.jclark.com/sp/catalog.htm">the SP Catalog page</a> from 3350 James Clark. This is relatively old and not the preferred mode of 3351 operation of libxml.</li> 3352 <li><a href="http://www.oasis-open.org/committees/entity/spec.html">XML 3353 Catalogs</a> is far more flexible, more recent, uses an XML syntax and 3354 should scale quite better. This is the default option of libxml.</li> 3355</ul> 3356 3357<p></p> 3358 3359<h3><a name="Simple">Using catalog</a></h3> 3360 3361<p>In a normal environment libxml2 will by default check the presence of a 3362catalog in /etc/xml/catalog, and assuming it has been correctly populated, 3363the processing is completely transparent to the document user. To take a 3364concrete example, suppose you are authoring a DocBook document, this one 3365starts with the following DOCTYPE definition:</p> 3366<pre><?xml version='1.0'?> 3367<!DOCTYPE book PUBLIC "-//Norman Walsh//DTD DocBk XML V3.1.4//EN" 3368 "http://nwalsh.com/docbook/xml/3.1.4/db3xml.dtd"></pre> 3369 3370<p>When validating the document with libxml, the catalog will be 3371automatically consulted to lookup the public identifier "-//Norman Walsh//DTD 3372DocBk XML V3.1.4//EN" and the system identifier 3373"http://nwalsh.com/docbook/xml/3.1.4/db3xml.dtd", and if these entities have 3374been installed on your system and the catalogs actually point to them, libxml 3375will fetch them from the local disk.</p> 3376 3377<p style="font-size: 10pt"><strong>Note</strong>: Really don't use this 3378DOCTYPE example it's a really old version, but is fine as an example.</p> 3379 3380<p>Libxml2 will check the catalog each time that it is requested to load an 3381entity, this includes DTD, external parsed entities, stylesheets, etc ... If 3382your system is correctly configured all the authoring phase and processing 3383should use only local files, even if your document stays portable because it 3384uses the canonical public and system ID, referencing the remote document.</p> 3385 3386<h3><a name="Some">Some examples:</a></h3> 3387 3388<p>Here is a couple of fragments from XML Catalogs used in libxml2 early 3389regression tests in <code>test/catalogs</code> :</p> 3390<pre><?xml version="1.0"?> 3391<!DOCTYPE catalog PUBLIC 3392 "-//OASIS//DTD Entity Resolution XML Catalog V1.0//EN" 3393 "http://www.oasis-open.org/committees/entity/release/1.0/catalog.dtd"> 3394<catalog xmlns="urn:oasis:names:tc:entity:xmlns:xml:catalog"> 3395 <public publicId="-//OASIS//DTD DocBook XML V4.1.2//EN" 3396 uri="http://www.oasis-open.org/docbook/xml/4.1.2/docbookx.dtd"/> 3397...</pre> 3398 3399<p>This is the beginning of a catalog for DocBook 4.1.2, XML Catalogs are 3400written in XML, there is a specific namespace for catalog elements 3401"urn:oasis:names:tc:entity:xmlns:xml:catalog". The first entry in this 3402catalog is a <code>public</code> mapping it allows to associate a Public 3403Identifier with an URI.</p> 3404<pre>... 3405 <rewriteSystem systemIdStartString="http://www.oasis-open.org/docbook/" 3406 rewritePrefix="file:///usr/share/xml/docbook/"/> 3407...</pre> 3408 3409<p>A <code>rewriteSystem</code> is a very powerful instruction, it says that 3410any URI starting with a given prefix should be looked at another URI 3411constructed by replacing the prefix with an new one. In effect this acts like 3412a cache system for a full area of the Web. In practice it is extremely useful 3413with a file prefix if you have installed a copy of those resources on your 3414local system.</p> 3415<pre>... 3416<delegatePublic publicIdStartString="-//OASIS//DTD XML Catalog //" 3417 catalog="file:///usr/share/xml/docbook.xml"/> 3418<delegatePublic publicIdStartString="-//OASIS//ENTITIES DocBook XML" 3419 catalog="file:///usr/share/xml/docbook.xml"/> 3420<delegatePublic publicIdStartString="-//OASIS//DTD DocBook XML" 3421 catalog="file:///usr/share/xml/docbook.xml"/> 3422<delegateSystem systemIdStartString="http://www.oasis-open.org/docbook/" 3423 catalog="file:///usr/share/xml/docbook.xml"/> 3424<delegateURI uriStartString="http://www.oasis-open.org/docbook/" 3425 catalog="file:///usr/share/xml/docbook.xml"/> 3426...</pre> 3427 3428<p>Delegation is the core features which allows to build a tree of catalogs, 3429easier to maintain than a single catalog, based on Public Identifier, System 3430Identifier or URI prefixes it instructs the catalog software to look up 3431entries in another resource. This feature allow to build hierarchies of 3432catalogs, the set of entries presented should be sufficient to redirect the 3433resolution of all DocBook references to the specific catalog in 3434<code>/usr/share/xml/docbook.xml</code> this one in turn could delegate all 3435references for DocBook 4.2.1 to a specific catalog installed at the same time 3436as the DocBook resources on the local machine.</p> 3437 3438<h3><a name="reference">How to tune catalog usage:</a></h3> 3439 3440<p>The user can change the default catalog behaviour by redirecting queries 3441to its own set of catalogs, this can be done by setting the 3442<code>XML_CATALOG_FILES</code> environment variable to a list of catalogs, an 3443empty one should deactivate loading the default <code>/etc/xml/catalog</code> 3444default catalog</p> 3445 3446<h3><a name="validate">How to debug catalog processing:</a></h3> 3447 3448<p>Setting up the <code>XML_DEBUG_CATALOG</code> environment variable will 3449make libxml2 output debugging informations for each catalog operations, for 3450example:</p> 3451<pre>orchis:~/XML -> xmllint --memory --noout test/ent2 3452warning: failed to load external entity "title.xml" 3453orchis:~/XML -> export XML_DEBUG_CATALOG= 3454orchis:~/XML -> xmllint --memory --noout test/ent2 3455Failed to parse catalog /etc/xml/catalog 3456Failed to parse catalog /etc/xml/catalog 3457warning: failed to load external entity "title.xml" 3458Catalogs cleanup 3459orchis:~/XML -> </pre> 3460 3461<p>The test/ent2 references an entity, running the parser from memory makes 3462the base URI unavailable and the the "title.xml" entity cannot be loaded. 3463Setting up the debug environment variable allows to detect that an attempt is 3464made to load the <code>/etc/xml/catalog</code> but since it's not present the 3465resolution fails.</p> 3466 3467<p>But the most advanced way to debug XML catalog processing is to use the 3468<strong>xmlcatalog</strong> command shipped with libxml2, it allows to load 3469catalogs and make resolution queries to see what is going on. This is also 3470used for the regression tests:</p> 3471<pre>orchis:~/XML -> /xmlcatalog test/catalogs/docbook.xml \ 3472 "-//OASIS//DTD DocBook XML V4.1.2//EN" 3473http://www.oasis-open.org/docbook/xml/4.1.2/docbookx.dtd 3474orchis:~/XML -> </pre> 3475 3476<p>For debugging what is going on, adding one -v flags increase the verbosity 3477level to indicate the processing done (adding a second flag also indicate 3478what elements are recognized at parsing):</p> 3479<pre>orchis:~/XML -> /xmlcatalog -v test/catalogs/docbook.xml \ 3480 "-//OASIS//DTD DocBook XML V4.1.2//EN" 3481Parsing catalog test/catalogs/docbook.xml's content 3482Found public match -//OASIS//DTD DocBook XML V4.1.2//EN 3483http://www.oasis-open.org/docbook/xml/4.1.2/docbookx.dtd 3484Catalogs cleanup 3485orchis:~/XML -> </pre> 3486 3487<p>A shell interface is also available to debug and process multiple queries 3488(and for regression tests):</p> 3489<pre>orchis:~/XML -> /xmlcatalog -shell test/catalogs/docbook.xml \ 3490 "-//OASIS//DTD DocBook XML V4.1.2//EN" 3491> help 3492Commands available: 3493public PublicID: make a PUBLIC identifier lookup 3494system SystemID: make a SYSTEM identifier lookup 3495resolve PublicID SystemID: do a full resolver lookup 3496add 'type' 'orig' 'replace' : add an entry 3497del 'values' : remove values 3498dump: print the current catalog state 3499debug: increase the verbosity level 3500quiet: decrease the verbosity level 3501exit: quit the shell 3502> public "-//OASIS//DTD DocBook XML V4.1.2//EN" 3503http://www.oasis-open.org/docbook/xml/4.1.2/docbookx.dtd 3504> quit 3505orchis:~/XML -> </pre> 3506 3507<p>This should be sufficient for most debugging purpose, this was actually 3508used heavily to debug the XML Catalog implementation itself.</p> 3509 3510<h3><a name="Declaring">How to create and maintain</a> catalogs:</h3> 3511 3512<p>Basically XML Catalogs are XML files, you can either use XML tools to 3513manage them or use <strong>xmlcatalog</strong> for this. The basic step is 3514to create a catalog the -create option provide this facility:</p> 3515<pre>orchis:~/XML -> /xmlcatalog --create tst.xml 3516<?xml version="1.0"?> 3517<!DOCTYPE catalog PUBLIC "-//OASIS//DTD Entity Resolution XML Catalog V1.0//EN" 3518 "http://www.oasis-open.org/committees/entity/release/1.0/catalog.dtd"> 3519<catalog xmlns="urn:oasis:names:tc:entity:xmlns:xml:catalog"/> 3520orchis:~/XML -> </pre> 3521 3522<p>By default xmlcatalog does not overwrite the original catalog and save the 3523result on the standard output, this can be overridden using the -noout 3524option. The <code>-add</code> command allows to add entries in the 3525catalog:</p> 3526<pre>orchis:~/XML -> /xmlcatalog --noout --create --add "public" \ 3527 "-//OASIS//DTD DocBook XML V4.1.2//EN" \ 3528 http://www.oasis-open.org/docbook/xml/4.1.2/docbookx.dtd tst.xml 3529orchis:~/XML -> cat tst.xml 3530<?xml version="1.0"?> 3531<!DOCTYPE catalog PUBLIC "-//OASIS//DTD Entity Resolution XML Catalog V1.0//EN" \ 3532 "http://www.oasis-open.org/committees/entity/release/1.0/catalog.dtd"> 3533<catalog xmlns="urn:oasis:names:tc:entity:xmlns:xml:catalog"> 3534<public publicId="-//OASIS//DTD DocBook XML V4.1.2//EN" 3535 uri="http://www.oasis-open.org/docbook/xml/4.1.2/docbookx.dtd"/> 3536</catalog> 3537orchis:~/XML -> </pre> 3538 3539<p>The <code>-add</code> option will always take 3 parameters even if some of 3540the XML Catalog constructs (like nextCatalog) will have only a single 3541argument, just pass a third empty string, it will be ignored.</p> 3542 3543<p>Similarly the <code>-del</code> option remove matching entries from the 3544catalog:</p> 3545<pre>orchis:~/XML -> /xmlcatalog --del \ 3546 "http://www.oasis-open.org/docbook/xml/4.1.2/docbookx.dtd" tst.xml 3547<?xml version="1.0"?> 3548<!DOCTYPE catalog PUBLIC "-//OASIS//DTD Entity Resolution XML Catalog V1.0//EN" 3549 "http://www.oasis-open.org/committees/entity/release/1.0/catalog.dtd"> 3550<catalog xmlns="urn:oasis:names:tc:entity:xmlns:xml:catalog"/> 3551orchis:~/XML -> </pre> 3552 3553<p>The catalog is now empty. Note that the matching of <code>-del</code> is 3554exact and would have worked in a similar fashion with the Public ID 3555string.</p> 3556 3557<p>This is rudimentary but should be sufficient to manage a not too complex 3558catalog tree of resources.</p> 3559 3560<h3><a name="implemento">The implementor corner quick review of the 3561API:</a></h3> 3562 3563<p>First, and like for every other module of libxml, there is an 3564automatically generated <a href="html/libxml-catalog.html">API page for 3565catalog support</a>.</p> 3566 3567<p>The header for the catalog interfaces should be included as:</p> 3568<pre>#include <libxml/catalog.h></pre> 3569 3570<p>The API is voluntarily kept very simple. First it is not obvious that 3571applications really need access to it since it is the default behaviour of 3572libxml2 (Note: it is possible to completely override libxml2 default catalog 3573by using <a href="html/libxml-parser.html">xmlSetExternalEntityLoader</a> to 3574plug an application specific resolver).</p> 3575 3576<p>Basically libxml2 support 2 catalog lists:</p> 3577<ul> 3578 <li>the default one, global shared by all the application</li> 3579 <li>a per-document catalog, this one is built if the document uses the 3580 <code>oasis-xml-catalog</code> PIs to specify its own catalog list, it is 3581 associated to the parser context and destroyed when the parsing context 3582 is destroyed.</li> 3583</ul> 3584 3585<p>the document one will be used first if it exists.</p> 3586 3587<h4>Initialization routines:</h4> 3588 3589<p>xmlInitializeCatalog(), xmlLoadCatalog() and xmlLoadCatalogs() should be 3590used at startup to initialize the catalog, if the catalog should be 3591initialized with specific values xmlLoadCatalog() or xmlLoadCatalogs() 3592should be called before xmlInitializeCatalog() which would otherwise do a 3593default initialization first.</p> 3594 3595<p>The xmlCatalogAddLocal() call is used by the parser to grow the document 3596own catalog list if needed.</p> 3597 3598<h4>Preferences setup:</h4> 3599 3600<p>The XML Catalog spec requires the possibility to select default 3601preferences between public and system delegation, 3602xmlCatalogSetDefaultPrefer() allows this, xmlCatalogSetDefaults() and 3603xmlCatalogGetDefaults() allow to control if XML Catalogs resolution should 3604be forbidden, allowed for global catalog, for document catalog or both, the 3605default is to allow both.</p> 3606 3607<p>And of course xmlCatalogSetDebug() allows to generate debug messages 3608(through the xmlGenericError() mechanism).</p> 3609 3610<h4>Querying routines:</h4> 3611 3612<p>xmlCatalogResolve(), xmlCatalogResolveSystem(), xmlCatalogResolvePublic() 3613and xmlCatalogResolveURI() are relatively explicit if you read the XML 3614Catalog specification they correspond to section 7 algorithms, they should 3615also work if you have loaded an SGML catalog with a simplified semantic.</p> 3616 3617<p>xmlCatalogLocalResolve() and xmlCatalogLocalResolveURI() are the same but 3618operate on the document catalog list</p> 3619 3620<h4>Cleanup and Miscellaneous:</h4> 3621 3622<p>xmlCatalogCleanup() free-up the global catalog, xmlCatalogFreeLocal() is 3623the per-document equivalent.</p> 3624 3625<p>xmlCatalogAdd() and xmlCatalogRemove() are used to dynamically modify the 3626first catalog in the global list, and xmlCatalogDump() allows to dump a 3627catalog state, those routines are primarily designed for xmlcatalog, I'm not 3628sure that exposing more complex interfaces (like navigation ones) would be 3629really useful.</p> 3630 3631<p>The xmlParseCatalogFile() is a function used to load XML Catalog files, 3632it's similar as xmlParseFile() except it bypass all catalog lookups, it's 3633provided because this functionality may be useful for client tools.</p> 3634 3635<h4>threaded environments:</h4> 3636 3637<p>Since the catalog tree is built progressively, some care has been taken to 3638try to avoid troubles in multithreaded environments. The code is now thread 3639safe assuming that the libxml2 library has been compiled with threads 3640support.</p> 3641 3642<p></p> 3643 3644<h3><a name="Other">Other resources</a></h3> 3645 3646<p>The XML Catalog specification is relatively recent so there isn't much 3647literature to point at:</p> 3648<ul> 3649 <li>You can find a good rant from Norm Walsh about <a 3650 href="http://www.arbortext.com/Think_Tank/XML_Resources/Issue_Three/issue_three.html">the 3651 need for catalogs</a>, it provides a lot of context informations even if 3652 I don't agree with everything presented. Norm also wrote a more recent 3653 article <a 3654 href="http://wwws.sun.com/software/xml/developers/resolver/article/">XML 3655 entities and URI resolvers</a> describing them.</li> 3656 <li>An <a href="http://home.ccil.org/~cowan/XML/XCatalog.html">old XML 3657 catalog proposal</a> from John Cowan</li> 3658 <li>The <a href="http://www.rddl.org/">Resource Directory Description 3659 Language</a> (RDDL) another catalog system but more oriented toward 3660 providing metadata for XML namespaces.</li> 3661 <li>the page from the OASIS Technical <a 3662 href="http://www.oasis-open.org/committees/entity/">Committee on Entity 3663 Resolution</a> who maintains XML Catalog, you will find pointers to the 3664 specification update, some background and pointers to others tools 3665 providing XML Catalog support</li> 3666 <li>There is a <a href="buildDocBookCatalog">shell script</a> to generate 3667 XML Catalogs for DocBook 4.1.2 . If it can write to the /etc/xml/ 3668 directory, it will set-up /etc/xml/catalog and /etc/xml/docbook based on 3669 the resources found on the system. Otherwise it will just create 3670 ~/xmlcatalog and ~/dbkxmlcatalog and doing: 3671 <p><code>export XML_CATALOG_FILES=$HOME/xmlcatalog</code></p> 3672 <p>should allow to process DocBook documentations without requiring 3673 network accesses for the DTD or stylesheets</p> 3674 </li> 3675 <li>I have uploaded <a href="ftp://xmlsoft.org/test/dbk412catalog.tar.gz">a 3676 small tarball</a> containing XML Catalogs for DocBook 4.1.2 which seems 3677 to work fine for me too</li> 3678 <li>The <a href="http://www.xmlsoft.org/xmlcatalog_man.html">xmlcatalog 3679 manual page</a></li> 3680</ul> 3681 3682<p>If you have suggestions for corrections or additions, simply contact 3683me:</p> 3684 3685<h2><a name="library">The parser interfaces</a></h2> 3686 3687<p>This section is directly intended to help programmers getting bootstrapped 3688using the XML tollkit from the C language. It is not intended to be 3689extensive. I hope the automatically generated documents will provide the 3690completeness required, but as a separate set of documents. The interfaces of 3691the XML parser are by principle low level, Those interested in a higher level 3692API should <a href="#DOM">look at DOM</a>.</p> 3693 3694<p>The <a href="html/libxml-parser.html">parser interfaces for XML</a> are 3695separated from the <a href="html/libxml-htmlparser.html">HTML parser 3696interfaces</a>. Let's have a look at how the XML parser can be called:</p> 3697 3698<h3><a name="Invoking">Invoking the parser : the pull method</a></h3> 3699 3700<p>Usually, the first thing to do is to read an XML input. The parser accepts 3701documents either from in-memory strings or from files. The functions are 3702defined in "parser.h":</p> 3703<dl> 3704 <dt><code>xmlDocPtr xmlParseMemory(char *buffer, int size);</code></dt> 3705 <dd><p>Parse a null-terminated string containing the document.</p> 3706 </dd> 3707</dl> 3708<dl> 3709 <dt><code>xmlDocPtr xmlParseFile(const char *filename);</code></dt> 3710 <dd><p>Parse an XML document contained in a (possibly compressed) 3711 file.</p> 3712 </dd> 3713</dl> 3714 3715<p>The parser returns a pointer to the document structure (or NULL in case of 3716failure).</p> 3717 3718<h3 id="Invoking1">Invoking the parser: the push method</h3> 3719 3720<p>In order for the application to keep the control when the document is 3721being fetched (which is common for GUI based programs) libxml2 provides a 3722push interface, too, as of version 1.8.3. Here are the interface 3723functions:</p> 3724<pre>xmlParserCtxtPtr xmlCreatePushParserCtxt(xmlSAXHandlerPtr sax, 3725 void *user_data, 3726 const char *chunk, 3727 int size, 3728 const char *filename); 3729int xmlParseChunk (xmlParserCtxtPtr ctxt, 3730 const char *chunk, 3731 int size, 3732 int terminate);</pre> 3733 3734<p>and here is a simple example showing how to use the interface:</p> 3735<pre> FILE *f; 3736 3737 f = fopen(filename, "r"); 3738 if (f != NULL) { 3739 int res, size = 1024; 3740 char chars[1024]; 3741 xmlParserCtxtPtr ctxt; 3742 3743 res = fread(chars, 1, 4, f); 3744 if (res > 0) { 3745 ctxt = xmlCreatePushParserCtxt(NULL, NULL, 3746 chars, res, filename); 3747 while ((res = fread(chars, 1, size, f)) > 0) { 3748 xmlParseChunk(ctxt, chars, res, 0); 3749 } 3750 xmlParseChunk(ctxt, chars, 0, 1); 3751 doc = ctxt->myDoc; 3752 xmlFreeParserCtxt(ctxt); 3753 } 3754 }</pre> 3755 3756<p>The HTML parser embedded into libxml2 also has a push interface; the 3757functions are just prefixed by "html" rather than "xml".</p> 3758 3759<h3 id="Invoking2">Invoking the parser: the SAX interface</h3> 3760 3761<p>The tree-building interface makes the parser memory-hungry, first loading 3762the document in memory and then building the tree itself. Reading a document 3763without building the tree is possible using the SAX interfaces (see SAX.h and 3764<a href="http://www.daa.com.au/~james/gnome/xml-sax/xml-sax.html">James 3765Henstridge's documentation</a>). Note also that the push interface can be 3766limited to SAX: just use the two first arguments of 3767<code>xmlCreatePushParserCtxt()</code>.</p> 3768 3769<h3><a name="Building">Building a tree from scratch</a></h3> 3770 3771<p>The other way to get an XML tree in memory is by building it. Basically 3772there is a set of functions dedicated to building new elements. (These are 3773also described in <libxml/tree.h>.) For example, here is a piece of 3774code that produces the XML document used in the previous examples:</p> 3775<pre> #include <libxml/tree.h> 3776 xmlDocPtr doc; 3777 xmlNodePtr tree, subtree; 3778 3779 doc = xmlNewDoc("1.0"); 3780 doc->children = xmlNewDocNode(doc, NULL, "EXAMPLE", NULL); 3781 xmlSetProp(doc->children, "prop1", "gnome is great"); 3782 xmlSetProp(doc->children, "prop2", "& linux too"); 3783 tree = xmlNewChild(doc->children, NULL, "head", NULL); 3784 subtree = xmlNewChild(tree, NULL, "title", "Welcome to Gnome"); 3785 tree = xmlNewChild(doc->children, NULL, "chapter", NULL); 3786 subtree = xmlNewChild(tree, NULL, "title", "The Linux adventure"); 3787 subtree = xmlNewChild(tree, NULL, "p", "bla bla bla ..."); 3788 subtree = xmlNewChild(tree, NULL, "image", NULL); 3789 xmlSetProp(subtree, "href", "linus.gif");</pre> 3790 3791<p>Not really rocket science ...</p> 3792 3793<h3><a name="Traversing">Traversing the tree</a></h3> 3794 3795<p>Basically by <a href="html/libxml-tree.html">including "tree.h"</a> your 3796code has access to the internal structure of all the elements of the tree. 3797The names should be somewhat simple like <strong>parent</strong>, 3798<strong>children</strong>, <strong>next</strong>, <strong>prev</strong>, 3799<strong>properties</strong>, etc... For example, still with the previous 3800example:</p> 3801<pre><code>doc->children->children->children</code></pre> 3802 3803<p>points to the title element,</p> 3804<pre>doc->children->children->next->children->children</pre> 3805 3806<p>points to the text node containing the chapter title "The Linux 3807adventure".</p> 3808 3809<p><strong>NOTE</strong>: XML allows <em>PI</em>s and <em>comments</em> to be 3810present before the document root, so <code>doc->children</code> may point 3811to an element which is not the document Root Element; a function 3812<code>xmlDocGetRootElement()</code> was added for this purpose.</p> 3813 3814<h3><a name="Modifying">Modifying the tree</a></h3> 3815 3816<p>Functions are provided for reading and writing the document content. Here 3817is an excerpt from the <a href="html/libxml-tree.html">tree API</a>:</p> 3818<dl> 3819 <dt><code>xmlAttrPtr xmlSetProp(xmlNodePtr node, const xmlChar *name, const 3820 xmlChar *value);</code></dt> 3821 <dd><p>This sets (or changes) an attribute carried by an ELEMENT node. 3822 The value can be NULL.</p> 3823 </dd> 3824</dl> 3825<dl> 3826 <dt><code>const xmlChar *xmlGetProp(xmlNodePtr node, const xmlChar 3827 *name);</code></dt> 3828 <dd><p>This function returns a pointer to new copy of the property 3829 content. Note that the user must deallocate the result.</p> 3830 </dd> 3831</dl> 3832 3833<p>Two functions are provided for reading and writing the text associated 3834with elements:</p> 3835<dl> 3836 <dt><code>xmlNodePtr xmlStringGetNodeList(xmlDocPtr doc, const xmlChar 3837 *value);</code></dt> 3838 <dd><p>This function takes an "external" string and converts it to one 3839 text node or possibly to a list of entity and text nodes. All 3840 non-predefined entity references like &Gnome; will be stored 3841 internally as entity nodes, hence the result of the function may not be 3842 a single node.</p> 3843 </dd> 3844</dl> 3845<dl> 3846 <dt><code>xmlChar *xmlNodeListGetString(xmlDocPtr doc, xmlNodePtr list, int 3847 inLine);</code></dt> 3848 <dd><p>This function is the inverse of 3849 <code>xmlStringGetNodeList()</code>. It generates a new string 3850 containing the content of the text and entity nodes. Note the extra 3851 argument inLine. If this argument is set to 1, the function will expand 3852 entity references. For example, instead of returning the &Gnome; 3853 XML encoding in the string, it will substitute it with its value (say, 3854 "GNU Network Object Model Environment").</p> 3855 </dd> 3856</dl> 3857 3858<h3><a name="Saving">Saving a tree</a></h3> 3859 3860<p>Basically 3 options are possible:</p> 3861<dl> 3862 <dt><code>void xmlDocDumpMemory(xmlDocPtr cur, xmlChar**mem, int 3863 *size);</code></dt> 3864 <dd><p>Returns a buffer into which the document has been saved.</p> 3865 </dd> 3866</dl> 3867<dl> 3868 <dt><code>extern void xmlDocDump(FILE *f, xmlDocPtr doc);</code></dt> 3869 <dd><p>Dumps a document to an open file descriptor.</p> 3870 </dd> 3871</dl> 3872<dl> 3873 <dt><code>int xmlSaveFile(const char *filename, xmlDocPtr cur);</code></dt> 3874 <dd><p>Saves the document to a file. In this case, the compression 3875 interface is triggered if it has been turned on.</p> 3876 </dd> 3877</dl> 3878 3879<h3><a name="Compressio">Compression</a></h3> 3880 3881<p>The library transparently handles compression when doing file-based 3882accesses. The level of compression on saves can be turned on either globally 3883or individually for one file:</p> 3884<dl> 3885 <dt><code>int xmlGetDocCompressMode (xmlDocPtr doc);</code></dt> 3886 <dd><p>Gets the document compression ratio (0-9).</p> 3887 </dd> 3888</dl> 3889<dl> 3890 <dt><code>void xmlSetDocCompressMode (xmlDocPtr doc, int mode);</code></dt> 3891 <dd><p>Sets the document compression ratio.</p> 3892 </dd> 3893</dl> 3894<dl> 3895 <dt><code>int xmlGetCompressMode(void);</code></dt> 3896 <dd><p>Gets the default compression ratio.</p> 3897 </dd> 3898</dl> 3899<dl> 3900 <dt><code>void xmlSetCompressMode(int mode);</code></dt> 3901 <dd><p>Sets the default compression ratio.</p> 3902 </dd> 3903</dl> 3904 3905<h2><a name="Entities">Entities or no entities</a></h2> 3906 3907<p>Entities in principle are similar to simple C macros. An entity defines an 3908abbreviation for a given string that you can reuse many times throughout the 3909content of your document. Entities are especially useful when a given string 3910may occur frequently within a document, or to confine the change needed to a 3911document to a restricted area in the internal subset of the document (at the 3912beginning). Example:</p> 3913<pre>1 <?xml version="1.0"?> 39142 <!DOCTYPE EXAMPLE SYSTEM "example.dtd" [ 39153 <!ENTITY xml "Extensible Markup Language"> 39164 ]> 39175 <EXAMPLE> 39186 &xml; 39197 </EXAMPLE></pre> 3920 3921<p>Line 3 declares the xml entity. Line 6 uses the xml entity, by prefixing 3922its name with '&' and following it by ';' without any spaces added. There 3923are 5 predefined entities in libxml2 allowing you to escape characters with 3924predefined meaning in some parts of the xml document content: 3925<strong>&lt;</strong> for the character '<', <strong>&gt;</strong> 3926for the character '>', <strong>&apos;</strong> for the character ''', 3927<strong>&quot;</strong> for the character '"', and 3928<strong>&amp;</strong> for the character '&'.</p> 3929 3930<p>One of the problems related to entities is that you may want the parser to 3931substitute an entity's content so that you can see the replacement text in 3932your application. Or you may prefer to keep entity references as such in the 3933content to be able to save the document back without losing this usually 3934precious information (if the user went through the pain of explicitly 3935defining entities, he may have a a rather negative attitude if you blindly 3936substitute them as saving time). The <a 3937href="html/libxml-parser.html#xmlSubstituteEntitiesDefault">xmlSubstituteEntitiesDefault()</a> 3938function allows you to check and change the behaviour, which is to not 3939substitute entities by default.</p> 3940 3941<p>Here is the DOM tree built by libxml2 for the previous document in the 3942default case:</p> 3943<pre>/gnome/src/gnome-xml -> /xmllint --debug test/ent1 3944DOCUMENT 3945version=1.0 3946 ELEMENT EXAMPLE 3947 TEXT 3948 content= 3949 ENTITY_REF 3950 INTERNAL_GENERAL_ENTITY xml 3951 content=Extensible Markup Language 3952 TEXT 3953 content=</pre> 3954 3955<p>And here is the result when substituting entities:</p> 3956<pre>/gnome/src/gnome-xml -> /tester --debug --noent test/ent1 3957DOCUMENT 3958version=1.0 3959 ELEMENT EXAMPLE 3960 TEXT 3961 content= Extensible Markup Language</pre> 3962 3963<p>So, entities or no entities? Basically, it depends on your use case. I 3964suggest that you keep the non-substituting default behaviour and avoid using 3965entities in your XML document or data if you are not willing to handle the 3966entity references elements in the DOM tree.</p> 3967 3968<p>Note that at save time libxml2 enforces the conversion of the predefined 3969entities where necessary to prevent well-formedness problems, and will also 3970transparently replace those with chars (i.e. it will not generate entity 3971reference elements in the DOM tree or call the reference() SAX callback when 3972finding them in the input).</p> 3973 3974<p><span style="background-color: #FF0000">WARNING</span>: handling entities 3975on top of the libxml2 SAX interface is difficult!!! If you plan to use 3976non-predefined entities in your documents, then the learning curve to handle 3977then using the SAX API may be long. If you plan to use complex documents, I 3978strongly suggest you consider using the DOM interface instead and let libxml 3979deal with the complexity rather than trying to do it yourself.</p> 3980 3981<h2><a name="Namespaces">Namespaces</a></h2> 3982 3983<p>The libxml2 library implements <a 3984href="http://www.w3.org/TR/REC-xml-names/">XML namespaces</a> support by 3985recognizing namespace constructs in the input, and does namespace lookup 3986automatically when building the DOM tree. A namespace declaration is 3987associated with an in-memory structure and all elements or attributes within 3988that namespace point to it. Hence testing the namespace is a simple and fast 3989equality operation at the user level.</p> 3990 3991<p>I suggest that people using libxml2 use a namespace, and declare it in the 3992root element of their document as the default namespace. Then they don't need 3993to use the prefix in the content but we will have a basis for future semantic 3994refinement and merging of data from different sources. This doesn't increase 3995the size of the XML output significantly, but significantly increases its 3996value in the long-term. Example:</p> 3997<pre><mydoc xmlns="http://mydoc.example.org/schemas/"> 3998 <elem1>...</elem1> 3999 <elem2>...</elem2> 4000</mydoc></pre> 4001 4002<p>The namespace value has to be an absolute URL, but the URL doesn't have to 4003point to any existing resource on the Web. It will bind all the element and 4004attributes with that URL. I suggest to use an URL within a domain you 4005control, and that the URL should contain some kind of version information if 4006possible. For example, <code>"http://www.gnome.org/gnumeric/1.0/"</code> is a 4007good namespace scheme.</p> 4008 4009<p>Then when you load a file, make sure that a namespace carrying the 4010version-independent prefix is installed on the root element of your document, 4011and if the version information don't match something you know, warn the user 4012and be liberal in what you accept as the input. Also do *not* try to base 4013namespace checking on the prefix value. <foo:text> may be exactly the 4014same as <bar:text> in another document. What really matters is the URI 4015associated with the element or the attribute, not the prefix string (which is 4016just a shortcut for the full URI). In libxml, element and attributes have an 4017<code>ns</code> field pointing to an xmlNs structure detailing the namespace 4018prefix and its URI.</p> 4019 4020<p>@@Interfaces@@</p> 4021<pre>xmlNodePtr node; 4022if(!strncmp(node->name,"mytag",5) 4023 && node->ns 4024 && !strcmp(node->ns->href,"http://www.mysite.com/myns/1.0")) { 4025 ... 4026}</pre> 4027 4028<p>Usually people object to using namespaces together with validity checking. 4029I will try to make sure that using namespaces won't break validity checking, 4030so even if you plan to use or currently are using validation I strongly 4031suggest adding namespaces to your document. A default namespace scheme 4032<code>xmlns="http://...."</code> should not break validity even on less 4033flexible parsers. Using namespaces to mix and differentiate content coming 4034from multiple DTDs will certainly break current validation schemes. To check 4035such documents one needs to use schema-validation, which is supported in 4036libxml2 as well. See <a href="http://www.relaxng.org/">relagx-ng</a> and <a 4037href="http://www.w3c.org/XML/Schema">w3c-schema</a>.</p> 4038 4039<h2><a name="Upgrading">Upgrading 1.x code</a></h2> 4040 4041<p>Incompatible changes:</p> 4042 4043<p>Version 2 of libxml2 is the first version introducing serious backward 4044incompatible changes. The main goals were:</p> 4045<ul> 4046 <li>a general cleanup. A number of mistakes inherited from the very early 4047 versions couldn't be changed due to compatibility constraints. Example 4048 the "childs" element in the nodes.</li> 4049 <li>Uniformization of the various nodes, at least for their header and link 4050 parts (doc, parent, children, prev, next), the goal is a simpler 4051 programming model and simplifying the task of the DOM implementors.</li> 4052 <li>better conformances to the XML specification, for example version 1.x 4053 had an heuristic to try to detect ignorable white spaces. As a result the 4054 SAX event generated were ignorableWhitespace() while the spec requires 4055 character() in that case. This also mean that a number of DOM node 4056 containing blank text may populate the DOM tree which were not present 4057 before.</li> 4058</ul> 4059 4060<h3>How to fix libxml-1.x code:</h3> 4061 4062<p>So client code of libxml designed to run with version 1.x may have to be 4063changed to compile against version 2.x of libxml. Here is a list of changes 4064that I have collected, they may not be sufficient, so in case you find other 4065change which are required, <a href="mailto:Daniel.Veillard@w3.org">drop me a 4066mail</a>:</p> 4067<ol> 4068 <li>The package name have changed from libxml to libxml2, the library name 4069 is now -lxml2 . There is a new xml2-config script which should be used to 4070 select the right parameters libxml2</li> 4071 <li>Node <strong>childs</strong> field has been renamed 4072 <strong>children</strong> so s/childs/children/g should be applied 4073 (probability of having "childs" anywhere else is close to 0+</li> 4074 <li>The document don't have anymore a <strong>root</strong> element it has 4075 been replaced by <strong>children</strong> and usually you will get a 4076 list of element here. For example a Dtd element for the internal subset 4077 and it's declaration may be found in that list, as well as processing 4078 instructions or comments found before or after the document root element. 4079 Use <strong>xmlDocGetRootElement(doc)</strong> to get the root element of 4080 a document. Alternatively if you are sure to not reference DTDs nor have 4081 PIs or comments before or after the root element 4082 s/->root/->children/g will probably do it.</li> 4083 <li>The white space issue, this one is more complex, unless special case of 4084 validating parsing, the line breaks and spaces usually used for indenting 4085 and formatting the document content becomes significant. So they are 4086 reported by SAX and if your using the DOM tree, corresponding nodes are 4087 generated. Too approach can be taken: 4088 <ol> 4089 <li>lazy one, use the compatibility call 4090 <strong>xmlKeepBlanksDefault(0)</strong> but be aware that you are 4091 relying on a special (and possibly broken) set of heuristics of 4092 libxml to detect ignorable blanks. Don't complain if it breaks or 4093 make your application not 100% clean w.r.t. to it's input.</li> 4094 <li>the Right Way: change you code to accept possibly insignificant 4095 blanks characters, or have your tree populated with weird blank text 4096 nodes. You can spot them using the commodity function 4097 <strong>xmlIsBlankNode(node)</strong> returning 1 for such blank 4098 nodes.</li> 4099 </ol> 4100 <p>Note also that with the new default the output functions don't add any 4101 extra indentation when saving a tree in order to be able to round trip 4102 (read and save) without inflating the document with extra formatting 4103 chars.</p> 4104 </li> 4105 <li>The include path has changed to $prefix/libxml/ and the includes 4106 themselves uses this new prefix in includes instructions... If you are 4107 using (as expected) the 4108 <pre>xml2-config --cflags</pre> 4109 <p>output to generate you compile commands this will probably work out of 4110 the box</p> 4111 </li> 4112 <li>xmlDetectCharEncoding takes an extra argument indicating the length in 4113 byte of the head of the document available for character detection.</li> 4114</ol> 4115 4116<h3>Ensuring both libxml-1.x and libxml-2.x compatibility</h3> 4117 4118<p>Two new version of libxml (1.8.11) and libxml2 (2.3.4) have been released 4119to allow smooth upgrade of existing libxml v1code while retaining 4120compatibility. They offers the following:</p> 4121<ol> 4122 <li>similar include naming, one should use 4123 <strong>#include<libxml/...></strong> in both cases.</li> 4124 <li>similar identifiers defined via macros for the child and root fields: 4125 respectively <strong>xmlChildrenNode</strong> and 4126 <strong>xmlRootNode</strong></li> 4127 <li>a new macro <strong>LIBXML_TEST_VERSION</strong> which should be 4128 inserted once in the client code</li> 4129</ol> 4130 4131<p>So the roadmap to upgrade your existing libxml applications is the 4132following:</p> 4133<ol> 4134 <li>install the libxml-1.8.8 (and libxml-devel-1.8.8) packages</li> 4135 <li>find all occurrences where the xmlDoc <strong>root</strong> field is 4136 used and change it to <strong>xmlRootNode</strong></li> 4137 <li>similarly find all occurrences where the xmlNode 4138 <strong>childs</strong> field is used and change it to 4139 <strong>xmlChildrenNode</strong></li> 4140 <li>add a <strong>LIBXML_TEST_VERSION</strong> macro somewhere in your 4141 <strong>main()</strong> or in the library init entry point</li> 4142 <li>Recompile, check compatibility, it should still work</li> 4143 <li>Change your configure script to look first for xml2-config and fall 4144 back using xml-config . Use the --cflags and --libs output of the command 4145 as the Include and Linking parameters needed to use libxml.</li> 4146 <li>install libxml2-2.3.x and libxml2-devel-2.3.x (libxml-1.8.y and 4147 libxml-devel-1.8.y can be kept simultaneously)</li> 4148 <li>remove your config.cache, relaunch your configuration mechanism, and 4149 recompile, if steps 2 and 3 were done right it should compile as-is</li> 4150 <li>Test that your application is still running correctly, if not this may 4151 be due to extra empty nodes due to formating spaces being kept in libxml2 4152 contrary to libxml1, in that case insert xmlKeepBlanksDefault(1) in your 4153 code before calling the parser (next to 4154 <strong>LIBXML_TEST_VERSION</strong> is a fine place).</li> 4155</ol> 4156 4157<p>Following those steps should work. It worked for some of my own code.</p> 4158 4159<p>Let me put some emphasis on the fact that there is far more changes from 4160libxml 1.x to 2.x than the ones you may have to patch for. The overall code 4161has been considerably cleaned up and the conformance to the XML specification 4162has been drastically improved too. Don't take those changes as an excuse to 4163not upgrade, it may cost a lot on the long term ...</p> 4164 4165<h2><a name="Thread">Thread safety</a></h2> 4166 4167<p>Starting with 2.4.7, libxml2 makes provisions to ensure that concurrent 4168threads can safely work in parallel parsing different documents. There is 4169however a couple of things to do to ensure it:</p> 4170<ul> 4171 <li>configure the library accordingly using the --with-threads options</li> 4172 <li>call xmlInitParser() in the "main" thread before using any of the 4173 libxml2 API (except possibly selecting a different memory allocator)</li> 4174</ul> 4175 4176<p>Note that the thread safety cannot be ensured for multiple threads sharing 4177the same document, the locking must be done at the application level, libxml 4178exports a basic mutex and reentrant mutexes API in <libxml/threads.h>. 4179The parts of the library checked for thread safety are:</p> 4180<ul> 4181 <li>concurrent loading</li> 4182 <li>file access resolution</li> 4183 <li>catalog access</li> 4184 <li>catalog building</li> 4185 <li>entities lookup/accesses</li> 4186 <li>validation</li> 4187 <li>global variables per-thread override</li> 4188 <li>memory handling</li> 4189</ul> 4190 4191<p>XPath is supposed to be thread safe now, but this wasn't tested 4192seriously.</p> 4193 4194<h2><a name="DOM"></a><a name="Principles">DOM Principles</a></h2> 4195 4196<p><a href="http://www.w3.org/DOM/">DOM</a> stands for the <em>Document 4197Object Model</em>; this is an API for accessing XML or HTML structured 4198documents. Native support for DOM in Gnome is on the way (module gnome-dom), 4199and will be based on gnome-xml. This will be a far cleaner interface to 4200manipulate XML files within Gnome since it won't expose the internal 4201structure.</p> 4202 4203<p>The current DOM implementation on top of libxml2 is the <a 4204href="http://cvs.gnome.org/lxr/source/gdome2/">gdome2 Gnome module</a>, this 4205is a full DOM interface, thanks to Paolo Casarini, check the <a 4206href="http://www.cs.unibo.it/~casarini/gdome2/">Gdome2 homepage</a> for more 4207informations.</p> 4208 4209<h2><a name="Example"></a><a name="real">A real example</a></h2> 4210 4211<p>Here is a real size example, where the actual content of the application 4212data is not kept in the DOM tree but uses internal structures. It is based on 4213a proposal to keep a database of jobs related to Gnome, with an XML based 4214storage structure. Here is an <a href="gjobs.xml">XML encoded jobs 4215base</a>:</p> 4216<pre><?xml version="1.0"?> 4217<gjob:Helping xmlns:gjob="http://www.gnome.org/some-location"> 4218 <gjob:Jobs> 4219 4220 <gjob:Job> 4221 <gjob:Project ID="3"/> 4222 <gjob:Application>GBackup</gjob:Application> 4223 <gjob:Category>Development</gjob:Category> 4224 4225 <gjob:Update> 4226 <gjob:Status>Open</gjob:Status> 4227 <gjob:Modified>Mon, 07 Jun 1999 20:27:45 -0400 MET DST</gjob:Modified> 4228 <gjob:Salary>USD 0.00</gjob:Salary> 4229 </gjob:Update> 4230 4231 <gjob:Developers> 4232 <gjob:Developer> 4233 </gjob:Developer> 4234 </gjob:Developers> 4235 4236 <gjob:Contact> 4237 <gjob:Person>Nathan Clemons</gjob:Person> 4238 <gjob:Email>nathan@windsofstorm.net</gjob:Email> 4239 <gjob:Company> 4240 </gjob:Company> 4241 <gjob:Organisation> 4242 </gjob:Organisation> 4243 <gjob:Webpage> 4244 </gjob:Webpage> 4245 <gjob:Snailmail> 4246 </gjob:Snailmail> 4247 <gjob:Phone> 4248 </gjob:Phone> 4249 </gjob:Contact> 4250 4251 <gjob:Requirements> 4252 The program should be released as free software, under the GPL. 4253 </gjob:Requirements> 4254 4255 <gjob:Skills> 4256 </gjob:Skills> 4257 4258 <gjob:Details> 4259 A GNOME based system that will allow a superuser to configure 4260 compressed and uncompressed files and/or file systems to be backed 4261 up with a supported media in the system. This should be able to 4262 perform via find commands generating a list of files that are passed 4263 to tar, dd, cpio, cp, gzip, etc., to be directed to the tape machine 4264 or via operations performed on the filesystem itself. Email 4265 notification and GUI status display very important. 4266 </gjob:Details> 4267 4268 </gjob:Job> 4269 4270 </gjob:Jobs> 4271</gjob:Helping></pre> 4272 4273<p>While loading the XML file into an internal DOM tree is a matter of 4274calling only a couple of functions, browsing the tree to gather the data and 4275generate the internal structures is harder, and more error prone.</p> 4276 4277<p>The suggested principle is to be tolerant with respect to the input 4278structure. For example, the ordering of the attributes is not significant, 4279the XML specification is clear about it. It's also usually a good idea not to 4280depend on the order of the children of a given node, unless it really makes 4281things harder. Here is some code to parse the information for a person:</p> 4282<pre>/* 4283 * A person record 4284 */ 4285typedef struct person { 4286 char *name; 4287 char *email; 4288 char *company; 4289 char *organisation; 4290 char *smail; 4291 char *webPage; 4292 char *phone; 4293} person, *personPtr; 4294 4295/* 4296 * And the code needed to parse it 4297 */ 4298personPtr parsePerson(xmlDocPtr doc, xmlNsPtr ns, xmlNodePtr cur) { 4299 personPtr ret = NULL; 4300 4301DEBUG("parsePerson\n"); 4302 /* 4303 * allocate the struct 4304 */ 4305 ret = (personPtr) malloc(sizeof(person)); 4306 if (ret == NULL) { 4307 fprintf(stderr,"out of memory\n"); 4308 return(NULL); 4309 } 4310 memset(ret, 0, sizeof(person)); 4311 4312 /* We don't care what the top level element name is */ 4313 cur = cur->xmlChildrenNode; 4314 while (cur != NULL) { 4315 if ((!strcmp(cur->name, "Person")) && (cur->ns == ns)) 4316 ret->name = xmlNodeListGetString(doc, cur->xmlChildrenNode, 1); 4317 if ((!strcmp(cur->name, "Email")) && (cur->ns == ns)) 4318 ret->email = xmlNodeListGetString(doc, cur->xmlChildrenNode, 1); 4319 cur = cur->next; 4320 } 4321 4322 return(ret); 4323}</pre> 4324 4325<p>Here are a couple of things to notice:</p> 4326<ul> 4327 <li>Usually a recursive parsing style is the more convenient one: XML data 4328 is by nature subject to repetitive constructs and usually exhibits highly 4329 structured patterns.</li> 4330 <li>The two arguments of type <em>xmlDocPtr</em> and <em>xmlNsPtr</em>, 4331 i.e. the pointer to the global XML document and the namespace reserved to 4332 the application. Document wide information are needed for example to 4333 decode entities and it's a good coding practice to define a namespace for 4334 your application set of data and test that the element and attributes 4335 you're analyzing actually pertains to your application space. This is 4336 done by a simple equality test (cur->ns == ns).</li> 4337 <li>To retrieve text and attributes value, you can use the function 4338 <em>xmlNodeListGetString</em> to gather all the text and entity reference 4339 nodes generated by the DOM output and produce an single text string.</li> 4340</ul> 4341 4342<p>Here is another piece of code used to parse another level of the 4343structure:</p> 4344<pre>#include <libxml/tree.h> 4345/* 4346 * a Description for a Job 4347 */ 4348typedef struct job { 4349 char *projectID; 4350 char *application; 4351 char *category; 4352 personPtr contact; 4353 int nbDevelopers; 4354 personPtr developers[100]; /* using dynamic alloc is left as an exercise */ 4355} job, *jobPtr; 4356 4357/* 4358 * And the code needed to parse it 4359 */ 4360jobPtr parseJob(xmlDocPtr doc, xmlNsPtr ns, xmlNodePtr cur) { 4361 jobPtr ret = NULL; 4362 4363DEBUG("parseJob\n"); 4364 /* 4365 * allocate the struct 4366 */ 4367 ret = (jobPtr) malloc(sizeof(job)); 4368 if (ret == NULL) { 4369 fprintf(stderr,"out of memory\n"); 4370 return(NULL); 4371 } 4372 memset(ret, 0, sizeof(job)); 4373 4374 /* We don't care what the top level element name is */ 4375 cur = cur->xmlChildrenNode; 4376 while (cur != NULL) { 4377 4378 if ((!strcmp(cur->name, "Project")) && (cur->ns == ns)) { 4379 ret->projectID = xmlGetProp(cur, "ID"); 4380 if (ret->projectID == NULL) { 4381 fprintf(stderr, "Project has no ID\n"); 4382 } 4383 } 4384 if ((!strcmp(cur->name, "Application")) && (cur->ns == ns)) 4385 ret->application = xmlNodeListGetString(doc, cur->xmlChildrenNode, 1); 4386 if ((!strcmp(cur->name, "Category")) && (cur->ns == ns)) 4387 ret->category = xmlNodeListGetString(doc, cur->xmlChildrenNode, 1); 4388 if ((!strcmp(cur->name, "Contact")) && (cur->ns == ns)) 4389 ret->contact = parsePerson(doc, ns, cur); 4390 cur = cur->next; 4391 } 4392 4393 return(ret); 4394}</pre> 4395 4396<p>Once you are used to it, writing this kind of code is quite simple, but 4397boring. Ultimately, it could be possible to write stubbers taking either C 4398data structure definitions, a set of XML examples or an XML DTD and produce 4399the code needed to import and export the content between C data and XML 4400storage. This is left as an exercise to the reader :-)</p> 4401 4402<p>Feel free to use <a href="example/gjobread.c">the code for the full C 4403parsing example</a> as a template, it is also available with Makefile in the 4404Gnome CVS base under gnome-xml/example</p> 4405 4406<h2><a name="Contributi">Contributions</a></h2> 4407<ul> 4408 <li>Bjorn Reese, William Brack and Thomas Broyer have provided a number of 4409 patches, Gary Pennington worked on the validation API, threading support 4410 and Solaris port.</li> 4411 <li>John Fleck helps maintaining the documentation and man pages.</li> 4412 <li><a href="mailto:igor@zlatkovic.com">Igor Zlatkovic</a> is now the 4413 maintainer of the Windows port, <a 4414 href="http://www.zlatkovic.com/projects/libxml/index.html">he provides 4415 binaries</a></li> 4416 <li><a href="mailto:Gary.Pennington@sun.com">Gary Pennington</a> provides 4417 <a href="http://garypennington.net/libxml2/">Solaris binaries</a></li> 4418 <li><a 4419 href="http://mail.gnome.org/archives/xml/2001-March/msg00014.html">Matt 4420 Sergeant</a> developed <a 4421 href="http://axkit.org/download/">XML::LibXSLT</a>, a Perl wrapper for 4422 libxml2/libxslt as part of the <a href="http://axkit.com/">AxKit XML 4423 application server</a></li> 4424 <li><a href="mailto:fnatter@gmx.net">Felix Natter</a> and <a 4425 href="mailto:geertk@ai.rug.nl">Geert Kloosterman</a> provide <a 4426 href="libxml-doc.el">an emacs module</a> to lookup libxml(2) functions 4427 documentation</li> 4428 <li><a href="mailto:sherwin@nlm.nih.gov">Ziying Sherwin</a> provided <a 4429 href="http://xmlsoft.org/messages/0488.html">man pages</a></li> 4430 <li>there is a module for <a 4431 href="http://acs-misc.sourceforge.net/nsxml.html">libxml/libxslt support 4432 in OpenNSD/AOLServer</a></li> 4433 <li><a href="mailto:dkuhlman@cutter.rexx.com">Dave Kuhlman</a> provided the 4434 first version of libxml/libxslt <a 4435 href="http://www.rexx.com/~dkuhlman">wrappers for Python</a></li> 4436 <li>Petr Kozelka provides <a 4437 href="http://sourceforge.net/projects/libxml2-pas">Pascal units to glue 4438 libxml2</a> with Kylix and Delphi and other Pascal compilers</li> 4439 <li><a href="mailto:aleksey@aleksey.com">Aleksey Sanin</a> implemented the 4440 <a href="http://www.w3.org/Signature/">XML Canonicalization and XML 4441 Digital Signature</a> <a 4442 href="http://www.aleksey.com/xmlsec/">implementations for libxml2</a></li> 4443 <li><a href="mailto:Steve.Ball@zveno.com">Steve Ball</a>, <a 4444 href="http://www.zveno.com/">Zveno</a> and contributors maintain <a 4445 href="http://tclxml.sourceforge.net/">tcl bindings for libxml2 and 4446 libxslt</a>, as well as <a 4447 href="http://tclxml.sf.net/tkxmllint.html">tkxmllint</a> a GUI for 4448 xmllint and <a href="http://tclxml.sf.net/tkxsltproc.html">tkxsltproc</a> 4449 a GUI for xsltproc.</li> 4450</ul> 4451 4452<p></p> 4453</body> 4454</html> 4455
