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blob: 205528f46349d03a4debb0683838e278e2d19500 [file] [log] [blame]
Daniel Veillard09ab7e12001-07-10 15:49:44 +0000[diff] [blame]1<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"
2 "http://www.w3.org/TR/html4/loose.dtd">
Daniel Veillardccb09631998-10-27 06:21:04 +0000[diff] [blame]3<html>
4<head>
Daniel Veillardec78c0f2000-08-25 10:25:23 +0000[diff] [blame]5 <title>The XML C library for Gnome</title>
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]6 <meta name="GENERATOR" content="amaya V5.0">
Daniel Veillardb24054a1999-12-18 15:32:46 +0000[diff] [blame]7 <meta http-equiv="Content-Type" content="text/html">
Daniel Veillardccb09631998-10-27 06:21:04 +0000[diff] [blame]8</head>
Daniel Veillardccb09631998-10-27 06:21:04 +0000[diff] [blame]9
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]10<body bgcolor="#ffffff">
Daniel Veillardec78c0f2000-08-25 10:25:23 +0000[diff] [blame]11<h1 align="center">The XML C library for Gnome</h1>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]12
Daniel Veillard9c466822001-10-25 12:03:39 +0000[diff] [blame]13<h1>Note: this is the flat content of the <a href="index.html">web
14site</a></h1>
15
Daniel Veillardc9484202001-10-24 12:35:52 +0000[diff] [blame]16<h1 style="text-align: center">libxml, a.k.a. gnome-xml</h1>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]17
18<p></p>
Daniel Veillard9c466822001-10-25 12:03:39 +0000[diff] [blame]19
20<p>Libxml is the XML C library developped for the Gnome project. XML itself
21is a metalanguage to design markup languages, i.e. text language where
22semantic and structure are added to the content using extra "markup"
23information enclosed between angle bracket. HTML is the most well-known
24markup language.</p>
25
26<p>Libxml2 implements a number of existing standards related to markup
27languages:</p>
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]28<ul>
Daniel Veillard9c466822001-10-25 12:03:39 +0000[diff] [blame]29 <li>the XML standard: <a
30 href="http://www.w3.org/TR/REC-xml">http://www.w3.org/TR/REC-xml</a></li>
31 <li>Namespaces in XML: <a
32 href="http://www.w3.org/TR/REC-xml-names/">http://www.w3.org/TR/REC-xml-names/</a></li>
33 <li>XML Base: <a
34 href="http://www.w3.org/TR/xmlbase/">http://www.w3.org/TR/xmlbase/</a></li>
35 <li><a href="http://www.cis.ohio-state.edu/rfc/rfc2396.txt">RFC 2396</a>
Daniel Veillardc6271d22001-10-27 07:50:58 +0000[diff] [blame]36 : Uniform Resource Identifiers <a
Daniel Veillard9c466822001-10-25 12:03:39 +0000[diff] [blame]37 href="http://www.ietf.org/rfc/rfc2396.txt">http://www.ietf.org/rfc/rfc2396.txt</a></li>
38 <li>XML Path Language (XPath) 1.0: <a
39 href="http://www.w3.org/TR/xpath">http://www.w3.org/TR/xpath</a></li>
40 <li>HTML4 parser: <a
41 href="http://www.w3.org/TR/html401/">http://www.w3.org/TR/html401/</a></li>
42 <li>most of XML Pointer Language (XPointer) Version 1.0: <a
43 href="http://www.w3.org/TR/xptr">http://www.w3.org/TR/xptr</a></li>
44 <li>XML Inclusions (XInclude) Version 1.0: <a
45 href="http://www.w3.org/TR/xinclude/">http://www.w3.org/TR/xinclude/</a></li>
46 <li>[ISO-8859-1], <a
47 href="http://www.cis.ohio-state.edu/rfc/rfc2044.txt">rfc2044</a> [UTF-8]
48 and <a href="http://www.cis.ohio-state.edu/rfc/rfc2781.txt">rfc2781</a>
49 [UTF-16] core encodings</li>
50 <li>part of SGML Open Technical Resolution TR9401:1997</li>
51 <li>XML Catalogs Working Draft 06 August 2001: <a
52 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>
Daniel Veillard96984452000-08-31 13:50:12 +0000[diff] [blame]53</ul>
54
Daniel Veillard9c466822001-10-25 12:03:39 +0000[diff] [blame]55<p>In most cases libxml tries to implement the specifications in a relatively
56strict way. To some extent libxml2 provide some support for the following
57other specification but don't claim to implement them:</p>
58<ul>
59 <li>Document Object Model (DOM) <a
60 href="http://www.w3.org/TR/DOM-Level-2-Core/">http://www.w3.org/TR/DOM-Level-2-Core/</a>
61 it doesn't implement the API itself, gdome2 does this in top of
62 libxml2</li>
63 <li><a href="http://www.cis.ohio-state.edu/rfc/rfc959.txt">RFC 959</a>
Daniel Veillardc6271d22001-10-27 07:50:58 +0000[diff] [blame]64 : libxml implements a basic FTP client code</li>
Daniel Veillard9c466822001-10-25 12:03:39 +0000[diff] [blame]65 <li><a href="http://www.cis.ohio-state.edu/rfc/rfc1945.txt">RFC 1945</a>
Daniel Veillardc6271d22001-10-27 07:50:58 +0000[diff] [blame]66 : HTTP/1.0, again a basic HTTP client code</li>
Daniel Veillard9c466822001-10-25 12:03:39 +0000[diff] [blame]67 <li>SAX: a minimal SAX implementation compatible with early expat
68 versions</li>
69 <li>DocBook SGML v4: libxml2 includes a hackish parser to transition to
70 XML</li>
71</ul>
72
73<p></p>
74
Daniel Veillard96984452000-08-31 13:50:12 +0000[diff] [blame]75<p>Separate documents:</p>
76<ul>
Daniel Veillardc6271d22001-10-27 07:50:58 +0000[diff] [blame]77 <li><a href="http://xmlsoft.org/XSLT/">the libxslt page</a>
78 providing an implementation of XSLT 1.0 and extensions on top of
79 libxml2</li>
80 <li><a href="http://www.cs.unibo.it/~casarini/gdome2/">the gdome2 page</a>
Daniel Veillard51095312001-10-28 18:51:57 +0000[diff] [blame]81 : a standard DOM2 implementation based on libxml2</li>
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]82</ul>
83
84<h2><a name="Introducti">Introduction</a></h2>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]85
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]86<p>This document describes libxml, the <a
Daniel Veillardec78c0f2000-08-25 10:25:23 +0000[diff] [blame]87href="http://www.w3.org/XML/">XML</a> C library developped for the <a
88href="http://www.gnome.org/">Gnome</a> project. <a
89href="http://www.w3.org/XML/">XML is a standard</a> for building tag-based
90structured documents/data.</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]91
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]92<p>Here are some key points about libxml:</p>
93<ul>
Daniel Veillard189446d2000-10-13 10:23:06 +0000[diff] [blame]94 <li>Libxml exports Push and Pull type parser interfaces for both XML and
95 HTML.</li>
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]96 <li>Libxml can do DTD validation at parse time, using a parsed document
97 instance, or with an arbitrary DTD.</li>
98 <li>Libxml now includes nearly complete <a
Daniel Veillard8c2ecaf2001-07-10 17:53:07 +0000[diff] [blame]99 href="http://www.w3.org/TR/xpath">XPath</a>, <a
100 href="http://www.w3.org/TR/xptr">XPointer</a> and <a
101 href="http://www.w3.org/TR/xinclude">XInclude</a> implementations.</li>
Daniel Veillardec78c0f2000-08-25 10:25:23 +0000[diff] [blame]102 <li>It is written in plain C, making as few assumptions as possible, and
Daniel Veillard189446d2000-10-13 10:23:06 +0000[diff] [blame]103 sticking closely to ANSI C/POSIX for easy embedding. Works on
Daniel Veillardab8500d2000-10-15 21:06:19 +0000[diff] [blame]104 Linux/Unix/Windows, ported to a number of other platforms.</li>
Daniel Veillardec70e912001-02-26 20:10:45 +0000[diff] [blame]105 <li>Basic support for HTTP and FTP client allowing aplications to fetch
106 remote resources</li>
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]107 <li>The design is modular, most of the extensions can be compiled out.</li>
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]108 <li>The internal document repesentation is as close as possible to the <a
109 href="http://www.w3.org/DOM/">DOM</a> interfaces.</li>
110 <li>Libxml also has a <a href="http://www.megginson.com/SAX/index.html">SAX
Daniel Veillard402e8c82000-02-29 22:57:47 +0000[diff] [blame]111 like interface</a>; the interface is designed to be compatible with <a
112 href="http://www.jclark.com/xml/expat.html">Expat</a>.</li>
Daniel Veillardec303412000-03-24 13:41:54 +0000[diff] [blame]113 <li>This library is released both under the <a
114 href="http://www.w3.org/Consortium/Legal/copyright-software-19980720.html">W3C
Daniel Veillard189446d2000-10-13 10:23:06 +0000[diff] [blame]115 IPR</a> and the <a href="http://www.gnu.org/copyleft/lesser.html">GNU
116 LGPL</a>. Use either at your convenience, basically this should make
117 everybody happy, if not, drop me a mail.</li>
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]118</ul>
Daniel Veillardccb09631998-10-27 06:21:04 +0000[diff] [blame]119
Daniel Veillarde0c1d722001-03-21 10:28:36 +0000[diff] [blame]120<p>Warning: unless you are forced to because your application links with a
121Gnome library requiring it, <strong><span
122style="background-color: #FF0000">Do Not Use libxml1</span></strong>, use
123libxml2</p>
124
Daniel Veillardb8cfbd12001-10-25 10:53:28 +0000[diff] [blame]125<h2><a name="FAQ">FAQ</a></h2>
126
127<p>Table of Content:</p>
128<ul>
129 <li><a href="FAQ.html#Licence">Licence(s)</a></li>
130 <li><a href="FAQ.html#Installati">Installation</a></li>
131 <li><a href="FAQ.html#Compilatio">Compilation</a></li>
132 <li><a href="FAQ.html#Developer">Developer corner</a></li>
133</ul>
134
135<h3><a name="Licence">Licence</a>(s)</h3>
136<ol>
137 <li><em>Licensing Terms for libxml</em>
138 <p>libxml is released under 2 (compatible) licences:</p>
139 <ul>
140 <li>the <a href="http://www.gnu.org/copyleft/lgpl.html">LGPL</a>: GNU
141 Library General Public License</li>
142 <li>the <a
143 href="http://www.w3.org/Consortium/Legal/copyright-software-19980720.html">W3C
144 IPR</a>: very similar to the XWindow licence</li>
145 </ul>
146 </li>
147 <li><em>Can I embed libxml in a proprietary application ?</em>
148 <p>Yes. The W3C IPR allows you to also keep proprietary the changes you
149 made to libxml, but it would be graceful to provide back bugfixes and
150 improvements as patches for possible incorporation in the main
151 development tree</p>
152 </li>
153</ol>
154
155<h3><a name="Installati">Installation</a></h3>
156<ol>
157 <li>Unless you are forced to because your application links with a Gnome
158 library requiring it, <strong><span style="background-color: #FF0000">Do
159 Not Use libxml1</span></strong>, use libxml2</li>
160 <li><em>Where can I get libxml</em>
161 ?
162 <p>The original distribution comes from <a
163 href="ftp://rpmfind.net/pub/libxml/">rpmfind.net</a> or <a
164 href="ftp://ftp.gnome.org/pub/GNOME/stable/sources/libxml/">gnome.org</a></p>
165 <p>Most linux and Bsd distribution includes libxml, this is probably the
166 safer way for end-users</p>
167 <p>David Doolin provides precompiled Windows versions at <a
168 href="http://www.ce.berkeley.edu/~doolin/code/libxmlwin32/ ">http://www.ce.berkeley.edu/~doolin/code/libxmlwin32/</a></p>
169 </li>
170 <li><em>I see libxml and libxml2 releases, which one should I install ?</em>
171 <ul>
172 <li>If you are not concerned by any existing backward compatibility
173 with existing application, install libxml2 only</li>
174 <li>If you are not doing development, you can safely install both.
175 usually the packages <a
176 href="http://rpmfind.net/linux/RPM/libxml.html">libxml</a> and <a
177 href="http://rpmfind.net/linux/RPM/libxml2.html">libxml2</a> are
178 compatible (this is not the case for development packages)</li>
179 <li>If you are a developer and your system provides separate packaging
180 for shared libraries and the development components, it is possible
181 to install libxml and libxml2, and also <a
182 href="http://rpmfind.net/linux/RPM/libxml-devel.html">libxml-devel</a>
183 and <a
184 href="http://rpmfind.net/linux/RPM/libxml2-devel.html">libxml2-devel</a>
185 too for libxml2 &gt;= 2.3.0</li>
186 <li>If you are developing a new application, please develop against
187 libxml2(-devel)</li>
188 </ul>
189 </li>
190 <li><em>I can't install the libxml package it conflicts with libxml0</em>
191 <p>You probably have an old libxml0 package used to provide the shared
192 library for libxml.so.0, you can probably safely remove it. Anyway the
193 libxml packages provided on <a
194 href="ftp://rpmfind.net/pub/libxml/">rpmfind.net</a> provides
195 libxml.so.0</p>
196 </li>
197 <li><em>I can't install the libxml(2) RPM package due to failed
198 dependancies</em>
199 <p>The most generic solution is to refetch the latest src.rpm , and
200 rebuild it locally with</p>
201 <p><code>rpm --rebuild libxml(2)-xxx.src.rpm</code></p>
202 <p>if everything goes well it will generate two binary rpm (one providing
203 the shared libs and xmllint, and the other one, the -devel package
204 providing includes, static libraries and scripts needed to build
205 applications with libxml(2)) that you can install locally.</p>
206 </li>
207</ol>
208
209<h3><a name="Compilatio">Compilation</a></h3>
210<ol>
211 <li><em>What is the process to compile libxml ?</em>
212 <p>As most UNIX libraries libxml follows the "standard":</p>
213 <p><code>gunzip -c xxx.tar.gz | tar xvf -</code></p>
214 <p><code>cd libxml-xxxx</code></p>
215 <p><code>./configure --help</code></p>
216 <p>to see the options, then the compilation/installation proper</p>
217 <p><code>./configure [possible options]</code></p>
218 <p><code>make</code></p>
219 <p><code>make install</code></p>
220 <p>At that point you may have to rerun ldconfig or similar utility to
221 update your list of installed shared libs.</p>
222 </li>
223 <li><em>What other libraries are needed to compile/install libxml ?</em>
224 <p>Libxml does not requires any other library, the normal C ANSI API
225 should be sufficient (please report any violation to this rule you may
226 find).</p>
227 <p>However if found at configuration time libxml will detect and use the
228 following libs:</p>
229 <ul>
230 <li><a href="http://www.info-zip.org/pub/infozip/zlib/">libz</a>
231 : a highly portable and available widely compression library</li>
232 <li>iconv: a powerful character encoding conversion library. It's
233 included by default on recent glibc libraries, so it doesn't need to
234 be installed specifically on linux. It seems it's now <a
235 href="http://www.opennc.org/onlinepubs/7908799/xsh/iconv.html">part
236 of the official UNIX</a> specification. Here is one <a
237 href="http://clisp.cons.org/~haible/packages-libiconv.html">implementation
238 of the library</a> which source can be found <a
239 href="ftp://ftp.ilog.fr/pub/Users/haible/gnu/">here</a>.</li>
240 </ul>
241 </li>
242 <li><em>libxml does not compile with HP-UX's optional ANSI-C compiler</em>
243 <p>this is due to macro limitations. Try to add " -Wp,-H16800 -Ae" to the
244 CFLAGS</p>
245 <p>you can also install and use gcc instead or use a precompiled version
246 of libxml, both available from the <a
247 href="http://hpux.cae.wisc.edu/hppd/auto/summary_all.html">HP-UX Porting
248 and Archive Centre</a></p>
249 </li>
250 <li><em>make check fails on some platforms</em>
251 <p>Sometime the regression tests results don't completely match the value
252 produced by the parser, and the makefile uses diff to print the delta. On
253 some platforms the diff return breaks the compilation process, if the
254 diff is small this is probably not a serious problem</p>
255 </li>
256 <li><em>I use the CVS version and there is no configure script</em>
257 <p>The configure (and other Makefiles) are generated. Use the autogen.sh
258 script to regenerate the configure and Makefiles, like:</p>
259 <p><code>./autogen.sh --prefix=/usr --disable-shared</code></p>
260 </li>
261 <li><em>I have troubles when running make tests with gcc-3.0</em>
262 <p>It seems the initial release of gcc-3.0 has a problem with the
263 optimizer which miscompiles the URI module. Please use another
264 compiler</p>
265 </li>
266</ol>
267
268<h3><a name="Developer">Developer</a> corner</h3>
269<ol>
270 <li><em>xmlDocDump() generates output on one line</em>
271 <p>libxml will not <strong>invent</strong> spaces in the content of a
272 document since <strong>all spaces in the content of a document are
273 significant</strong>. If you build a tree from the API and want
274 indentation:</p>
275 <ol>
276 <li>the correct way is to generate those yourself too</li>
277 <li>the dangerous way is to ask libxml to add those blanks to your
278 content <strong>modifying the content of your document in the
279 process</strong>. The result may not be what you expect. There is
280 <strong>NO</strong> way to guarantee that such a modification won't
281 impact other part of the content of your document. See <a
282 href="http://xmlsoft.org/html/libxml-parser.html#XMLKEEPBLANKSDEFAULT">xmlKeepBlanksDefault
283 ()</a> and <a
284 href="http://xmlsoft.org/html/libxml-tree.html#XMLSAVEFORMATFILE">xmlSaveFormatFile
285 ()</a></li>
286 </ol>
287 </li>
288 <li>Extra nodes in the document:
289 <p><em>For a XML file as below:</em></p>
290 <pre>&lt;?xml version="1.0"?&gt;
291&lt;PLAN xmlns="http://www.argus.ca/autotest/1.0/"&gt;
292&lt;NODE CommFlag="0"/&gt;
293&lt;NODE CommFlag="1"/&gt;
294&lt;/PLAN&gt;</pre>
295 <p><em>after parsing it with the function
296 pxmlDoc=xmlParseFile(...);</em></p>
297 <p><em>I want to the get the content of the first node (node with the
298 CommFlag="0")</em></p>
299 <p><em>so I did it as following;</em></p>
300 <pre>xmlNodePtr pode;
301pnode=pxmlDoc-&gt;children-&gt;children;</pre>
302 <p><em>but it does not work. If I change it to</em></p>
303 <pre>pnode=pxmlDoc-&gt;children-&gt;children-&gt;next;</pre>
304 <p><em>then it works. Can someone explain it to me.</em></p>
305 <p></p>
306 <p>In XML all characters in the content of the document are significant
307 <strong>including blanks and formatting line breaks</strong>.</p>
308 <p>The extra nodes you are wondering about are just that, text nodes with
309 the formatting spaces wich are part of the document but that people tend
310 to forget. There is a function <a
311 href="http://xmlsoft.org/html/libxml-parser.html">xmlKeepBlanksDefault
312 ()</a> to remove those at parse time, but that's an heuristic, and its
313 use should be limited to case where you are sure there is no
314 mixed-content in the document.</p>
315 </li>
316 <li><em>I get compilation errors of existing code like when accessing
317 <strong>root</strong> or <strong>childs fields</strong> of nodes</em>
318 <p>You are compiling code developed for libxml version 1 and using a
319 libxml2 development environment. Either switch back to libxml v1 devel or
320 even better fix the code to compile with libxml2 (or both) by <a
321 href="upgrade.html">following the instructions</a>.</p>
322 </li>
323 <li><em>I get compilation errors about non existing
324 <strong>xmlRootNode</strong> or <strong>xmlChildrenNode</strong>
325 fields</em>
326 <p>The source code you are using has been <a
327 href="upgrade.html">upgraded</a> to be able to compile with both libxml
328 and libxml2, but you need to install a more recent version:
329 libxml(-devel) &gt;= 1.8.8 or libxml2(-devel) &gt;= 2.1.0</p>
330 </li>
331 <li><em>XPath implementation looks seriously broken</em>
332 <p>XPath implementation prior to 2.3.0 was really incomplete, upgrade to
333 a recent version, the implementation and debug of libxslt generated fixes
334 for most obvious problems.</p>
335 </li>
336 <li><em>The example provided in the web page does not compile</em>
337 <p>It's hard to maintain the documentation in sync with the code
338 &lt;grin/&gt; ...</p>
339 <p>Check the previous points 1/ and 2/ raised before, and send
340 patches.</p>
341 </li>
342 <li><em>Where can I get more examples and informations than in the web
343 page</em>
344 <p>Ideally a libxml book would be nice. I have no such plan ... But you
345 can:</p>
346 <ul>
347 <li>check more deeply the <a href="html/libxml-lib.html">existing
348 generated doc</a></li>
349 <li>looks for examples of use for libxml function using the Gnome code
350 for example the following will query the full Gnome CVs base for the
351 use of the <strong>xmlAddChild()</strong> function:
352 <p><a
353 href="http://cvs.gnome.org/lxr/search?string=xmlAddChild">http://cvs.gnome.org/lxr/search?string=xmlAddChild</a></p>
354 <p>This may be slow, a large hardware donation to the gnome project
355 could cure this :-)</p>
356 </li>
357 <li><a
358 href="http://cvs.gnome.org/bonsai/rview.cgi?cvsroot=/cvs/gnome&amp;dir=gnome-xml">Browse
359 the libxml source</a>
360 , I try to write code as clean and documented as possible, so
361 looking at it may be helpful</li>
362 </ul>
363 </li>
364 <li>What about C++ ?
365 <p>libxml is written in pure C in order to allow easy reuse on a number
366 of platforms, including embedded systems. I don't intend to convert to
367 C++.</p>
368 <p>There is however a C++ wrapper provided by Ari Johnson
369 &lt;ari@btigate.com&gt; which may fullfill your needs:</p>
370 <p>Website: <a
371 href="http://lusis.org/~ari/xml++/">http://lusis.org/~ari/xml++/</a></p>
372 <p>Download: <a
373 href="http://lusis.org/~ari/xml++/libxml++.tar.gz">http://lusis.org/~ari/xml++/libxml++.tar.gz</a></p>
374 </li>
375 <li>How to validate a document a posteriori ?
376 <p>It is possible to validate documents which had not been validated at
377 initial parsing time or documents who have been built from scratch using
378 the API. Use the <a
379 href="http://xmlsoft.org/html/libxml-valid.html#XMLVALIDATEDTD">xmlValidateDtd()</a>
380 function. It is also possible to simply add a Dtd to an existing
381 document:</p>
382 <pre>xmlDocPtr doc; /* your existing document */
383 xmlDtdPtr dtd = xmlParseDTD(NULL, filename_of_dtd); /* parse the DTD */
384 dtd-&gt;name = xmlStrDup((xmlChar*)"root_name"); /* use the given root */
385
386 doc-&gt;intSubset = dtd;
387 if (doc-&gt;children == NULL) xmlAddChild((xmlNodePtr)doc, (xmlNodePtr)dtd);
388 else xmlAddPrevSibling(doc-&gt;children, (xmlNodePtr)dtd);
389 </pre>
390 </li>
391 <li>etc ...</li>
392</ol>
393
394<p></p>
395
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]396<h2><a name="Documentat">Documentation</a></h2>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]397
Daniel Veillard402e8c82000-02-29 22:57:47 +0000[diff] [blame]398<p>There are some on-line resources about using libxml:</p>
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]399<ol>
Daniel Veillard365e13b2000-07-02 07:56:37 +0000[diff] [blame]400 <li>Check the <a href="FAQ.html">FAQ</a></li>
Daniel Veillardc19fccc2000-07-03 11:52:01 +0000[diff] [blame]401 <li>Check the <a href="http://xmlsoft.org/html/libxml-lib.html">extensive
Daniel Veillard8c6d6af2000-08-25 17:14:13 +0000[diff] [blame]402 documentation</a> automatically extracted from code comments (using <a
403 href="http://cvs.gnome.org/bonsai/rview.cgi?cvsroot=/cvs/gnome&amp;dir=gtk-doc">gtk
404 doc</a>).</li>
Daniel Veillard8d869642000-07-14 12:12:59 +0000[diff] [blame]405 <li>Look at the documentation about <a href="encoding.html">libxml
406 internationalization support</a></li>
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]407 <li>This page provides a global overview and <a href="#real">some
Daniel Veillard402e8c82000-02-29 22:57:47 +0000[diff] [blame]408 examples</a> on how to use libxml.</li>
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]409 <li><a href="mailto:james@daa.com.au">James Henstridge</a>
410 wrote <a
Daniel Veillard402e8c82000-02-29 22:57:47 +0000[diff] [blame]411 href="http://www.daa.com.au/~james/gnome/xml-sax/xml-sax.html">some nice
412 documentation</a> explaining how to use the libxml SAX interface.</li>
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]413 <li>George Lebl wrote <a
414 href="http://www-4.ibm.com/software/developer/library/gnome3/">an article
Daniel Veillard402e8c82000-02-29 22:57:47 +0000[diff] [blame]415 for IBM developerWorks</a> about using libxml.</li>
Daniel Veillardec303412000-03-24 13:41:54 +0000[diff] [blame]416 <li>Check <a href="http://cvs.gnome.org/lxr/source/gnome-xml/TODO">the TODO
417 file</a></li>
418 <li>Read the <a href="upgrade.html">1.x to 2.x upgrade path</a>. If you are
419 starting a new project using libxml you should really use the 2.x
420 version.</li>
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]421 <li>And don't forget to look at the <a href="/messages/">mailing-list
Daniel Veillardc310d562000-06-23 18:32:15 +0000[diff] [blame]422 archive</a>.</li>
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]423</ol>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]424
Daniel Veillardd5f97f82000-09-17 16:38:14 +0000[diff] [blame]425<h2><a name="Reporting">Reporting bugs and getting help</a></h2>
Daniel Veillard4c3a2031999-11-19 17:46:26 +0000[diff] [blame]426
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]427<p>Well, bugs or missing features are always possible, and I will make a
428point of fixing them in a timely fashion. The best way to report a bug is to
429use the <a href="http://bugzilla.gnome.org/buglist.cgi?product=libxml">Gnome
430bug tracking database</a> (make sure to use the "libxml" module name). I look
431at reports there regularly and it's good to have a reminder when a bug is
Daniel Veillard51095312001-10-28 18:51:57 +0000[diff] [blame]432still open. Be sure to specify that the bug is for the package libxml.</p>
Daniel Veillard4c3a2031999-11-19 17:46:26 +0000[diff] [blame]433
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]434<p>There is also a mailing-list <a
Daniel Veillard3197f162001-04-04 00:40:08 +0000[diff] [blame]435href="mailto:xml@gnome.org">xml@gnome.org</a> for libxml, with an <a
436href="http://mail.gnome.org/archives/xml/">on-line archive</a> (<a
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]437href="http://xmlsoft.org/messages">old</a>). To subscribe to this list,
438please visit the <a
439href="http://mail.gnome.org/mailman/listinfo/xml">associated Web</a> page and
440follow the instructions. <strong>Do not send code, I won't debug it</strong>
441(but patches are really appreciated!).</p>
Daniel Veillard234547b2001-07-05 09:46:10 +0000[diff] [blame]442
Daniel Veillard008186f2001-09-13 14:24:44 +0000[diff] [blame]443<p>Check the following <strong><span style="color: #FF0000">before
444posting</span></strong>:</p>
Daniel Veillard234547b2001-07-05 09:46:10 +0000[diff] [blame]445<ul>
Daniel Veillarddadd0872001-09-15 09:21:44 +0000[diff] [blame]446 <li>read the <a href="FAQ.html">FAQ</a></li>
Daniel Veillard234547b2001-07-05 09:46:10 +0000[diff] [blame]447 <li>make sure you are <a href="ftp://xmlsoft.org/">using a recent
448 version</a>, and that the problem still shows up in those</li>
449 <li>check the <a href="http://mail.gnome.org/archives/xml/">list
450 archives</a> to see if the problem was reported already, in this case
Daniel Veillarde7ead2d2001-08-22 23:44:09 +0000[diff] [blame]451 there is probably a fix available, similary check the <a
452 href="http://bugzilla.gnome.org/buglist.cgi?product=libxml">registered
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]453 open bugs</a></li>
Daniel Veillard234547b2001-07-05 09:46:10 +0000[diff] [blame]454 <li>make sure you can reproduce the bug with xmllint or one of the test
455 programs found in source in the distribution</li>
456 <li>Please send the command showing the error as well as the input (as an
457 attachement)</li>
458</ul>
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]459
Daniel Veillarddadd0872001-09-15 09:21:44 +0000[diff] [blame]460<p>Then send the bug with associated informations to reproduce it to the <a
Daniel Veillard33a67802001-03-07 09:44:02 +0000[diff] [blame]461href="mailto:xml@gnome.org">xml@gnome.org</a> list; if it's really libxml
Daniel Veillard008186f2001-09-13 14:24:44 +0000[diff] [blame]462related I will approve it.. Please do not send me mail directly, it makes
463things really harder to track and in some cases I'm not the best person to
464answer a given question, ask the list instead.</p>
Daniel Veillard4c3a2031999-11-19 17:46:26 +0000[diff] [blame]465
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]466<p>Of course, bugs reported with a suggested patch for fixing them will
Daniel Veillardec303412000-03-24 13:41:54 +0000[diff] [blame]467probably be processed faster.</p>
468
469<p>If you're looking for help, a quick look at <a
Daniel Veillardf7ed3362001-08-17 12:01:21 +0000[diff] [blame]470href="http://mail.gnome.org/archives/xml/">the list archive</a> may actually
Daniel Veillardec303412000-03-24 13:41:54 +0000[diff] [blame]471provide the answer, I usually send source samples when answering libxml usage
Daniel Veillard6f0adb52000-07-03 11:41:26 +0000[diff] [blame]472questions. The <a href="http://xmlsoft.org/html/book1.html">auto-generated
Daniel Veillardec303412000-03-24 13:41:54 +0000[diff] [blame]473documentantion</a> is not as polished as I would like (i need to learn more
474about Docbook), but it's a good starting point.</p>
475
Daniel Veillardd5f97f82000-09-17 16:38:14 +0000[diff] [blame]476<h2><a name="help">How to help</a></h2>
477
478<p>You can help the project in various ways, the best thing to do first is to
479subscribe to the mailing-list as explained before, check the <a
Daniel Veillardf7ed3362001-08-17 12:01:21 +0000[diff] [blame]480href="http://mail.gnome.org/archives/xml/">archives </a>and the <a
481href="http://bugzilla.gnome.org/buglist.cgi?product=libxml">Gnome bug
Daniel Veillardd5f97f82000-09-17 16:38:14 +0000[diff] [blame]482database:</a>:</p>
483<ol>
484 <li>provide patches when you find problems</li>
Daniel Veillard189446d2000-10-13 10:23:06 +0000[diff] [blame]485 <li>provide the diffs when you port libxml to a new platform. They may not
Daniel Veillardab8500d2000-10-15 21:06:19 +0000[diff] [blame]486 be integrated in all cases but help pinpointing portability problems
487 and</li>
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]488 <li>provide documentation fixes (either as patches to the code comments or
Daniel Veillardd5f97f82000-09-17 16:38:14 +0000[diff] [blame]489 as HTML diffs).</li>
490 <li>provide new documentations pieces (translations, examples, etc ...)</li>
491 <li>Check the TODO file and try to close one of the items</li>
492 <li>take one of the points raised in the archive or the bug database and
Daniel Veillarde7ead2d2001-08-22 23:44:09 +0000[diff] [blame]493 provide a fix. <a href="mailto:daniel@veillard.com">Get in touch with me
494 </a>before to avoid synchronization problems and check that the suggested
495 fix will fit in nicely :-)</li>
Daniel Veillardd5f97f82000-09-17 16:38:14 +0000[diff] [blame]496</ol>
497
Daniel Veillard10a2c651999-12-12 13:03:50 +0000[diff] [blame]498<h2><a name="Downloads">Downloads</a></h2>
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]499
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]500<p>The latest versions of libxml can be found on <a
Daniel Veillard20c8cf22001-06-26 22:47:36 +0000[diff] [blame]501href="ftp://xmlsoft.org/">xmlsoft.org</a> (<a
502href="ftp://speakeasy.rpmfind.net/pub/libxml/">Seattle</a>, <a
503href="ftp://fr.rpmfind.net/pub/libxml/">France</a>) or on the <a
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]504href="ftp://ftp.gnome.org/pub/GNOME/MIRRORS.html">Gnome FTP server</a> either
Daniel Veillard10a2c651999-12-12 13:03:50 +0000[diff] [blame]505as a <a href="ftp://ftp.gnome.org/pub/GNOME/stable/sources/libxml/">source
Daniel Veillard306be992000-07-03 12:38:45 +0000[diff] [blame]506archive</a> or <a
Daniel Veillarda41123c2001-04-22 19:31:20 +0000[diff] [blame]507href="ftp://ftp.gnome.org/pub/GNOME/stable/redhat/i386/libxml/">RPM
508packages</a>. (NOTE that you need both the <a
Daniel Veillardc19fccc2000-07-03 11:52:01 +0000[diff] [blame]509href="http://rpmfind.net/linux/RPM/libxml2.html">libxml(2)</a> and <a
510href="http://rpmfind.net/linux/RPM/libxml2-devel.html">libxml(2)-devel</a>
Daniel Veillard95189532001-07-26 18:30:26 +0000[diff] [blame]511packages installed to compile applications using libxml.) <a
512href="mailto:izlatkovic@daenet.de">Igor Zlatkovic</a> is now the maintainer
513of the Windows port, <a
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]514href="http://www.fh-frankfurt.de/~igor/projects/libxml/index.html">he
Daniel Veillardc6271d22001-10-27 07:50:58 +0000[diff] [blame]515provides binaries</a>. <a href="mailto:Gary.Pennington@sun.com">Gary
516Pennington</a> provides <a
517href="http://pages.eidosnet.co.uk/~garypen/libxml/">Solaris binaries</a>.</p>
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]518
Daniel Veillard6c8b1172000-03-01 00:40:41 +0000[diff] [blame]519<p><a name="Snapshot">Snapshot:</a></p>
520<ul>
521 <li>Code from the W3C cvs base libxml <a
Daniel Veillard33a67802001-03-07 09:44:02 +0000[diff] [blame]522 href="ftp://xmlsoft.org/cvs-snapshot.tar.gz">cvs-snapshot.tar.gz</a></li>
Daniel Veillard6c8b1172000-03-01 00:40:41 +0000[diff] [blame]523 <li>Docs, content of the web site, the list archive included <a
Daniel Veillard33a67802001-03-07 09:44:02 +0000[diff] [blame]524 href="ftp://xmlsoft.org/libxml-docs.tar.gz">libxml-docs.tar.gz</a></li>
Daniel Veillard6c8b1172000-03-01 00:40:41 +0000[diff] [blame]525</ul>
526
Daniel Veillardc6271d22001-10-27 07:50:58 +0000[diff] [blame]527<p><a name="Contribs">Contributions:</a></p>
Daniel Veillard6c8b1172000-03-01 00:40:41 +0000[diff] [blame]528
529<p>I do accept external contributions, especially if compiling on another
Daniel Veillardc6271d22001-10-27 07:50:58 +0000[diff] [blame]530platform, get in touch with me to upload the package, wrappers for various
Daniel Veillard51095312001-10-28 18:51:57 +0000[diff] [blame]531languages have been provided, and can be found in the <a
532href="contribs.html">contrib section</a></p>
Daniel Veillard6c8b1172000-03-01 00:40:41 +0000[diff] [blame]533
Daniel Veillard82687162001-01-22 15:32:01 +0000[diff] [blame]534<p>Libxml is also available from CVS:</p>
Daniel Veillard10a2c651999-12-12 13:03:50 +0000[diff] [blame]535<ul>
Daniel Veillard10a2c651999-12-12 13:03:50 +0000[diff] [blame]536 <li><p>The <a
537 href="http://cvs.gnome.org/bonsai/rview.cgi?cvsroot=/cvs/gnome&amp;dir=gnome-xml">Gnome
Daniel Veillard402e8c82000-02-29 22:57:47 +0000[diff] [blame]538 CVS base</a>. Check the <a
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]539 href="http://developer.gnome.org/tools/cvs.html">Gnome CVS Tools</a>
540 page; the CVS module is <b>gnome-xml</b>.</p>
Daniel Veillard10a2c651999-12-12 13:03:50 +0000[diff] [blame]541 </li>
Daniel Veillard82687162001-01-22 15:32:01 +0000[diff] [blame]542 <li>The <strong>libxslt</strong> module is also present there</li>
Daniel Veillard10a2c651999-12-12 13:03:50 +0000[diff] [blame]543</ul>
544
545<h2><a name="News">News</a></h2>
546
Daniel Veillard944b5ff1999-12-15 19:08:24 +0000[diff] [blame]547<h3>CVS only : check the <a
548href="http://cvs.gnome.org/lxr/source/gnome-xml/ChangeLog">Changelog</a> file
Daniel Veillard189446d2000-10-13 10:23:06 +0000[diff] [blame]549for a really accurate description</h3>
Daniel Veillardab8500d2000-10-15 21:06:19 +0000[diff] [blame]550
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]551<p>Items floating around but not actively worked on, get in touch with me if
Daniel Veillardab8500d2000-10-15 21:06:19 +0000[diff] [blame]552you want to test those</p>
553<ul>
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]554 <li>Implementing <a href="http://xmlsoft.org/XSLT">XSLT</a>, this is done
555 as a separate C library on top of libxml called libxslt</li>
Daniel Veillard28929b22000-11-13 18:22:49 +0000[diff] [blame]556 <li>Finishing up <a href="http://www.w3.org/TR/xptr">XPointer</a> and <a
557 href="http://www.w3.org/TR/xinclude">XInclude</a></li>
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]558 <li>(seeems working but delayed from release) parsing/import of Docbook
559 SGML docs</li>
560</ul>
561
Daniel Veillarded421aa2001-11-04 21:22:45 +0000[diff] [blame^]562<h3>2.4.8: Nov 4 2001</h3>
563<ul>
564 <li>fixed SGML catalogs broken in previous release, updated xmlcatalog
565 tool</li>
566 <li>fixed a compile errors and some includes troubles.</li>
567</ul>
568
Daniel Veillard52dcab32001-10-30 12:51:17 +0000[diff] [blame]569<h3>2.4.7: Oct 30 2001</h3>
570<ul>
571 <li>exported some debugging interfaces</li>
572 <li>serious rewrite of the catalog code</li>
573 <li>integrated Gary Pennington thread safety patch, added configure option
574 and regression tests</li>
575 <li>removed an HTML parser bug</li>
576 <li>fixed a couple of potentially serious validation bugs</li>
577 <li>integrated the SGML DocBook support in xmllint</li>
578 <li>changed the nanoftp anonymous login passwd</li>
579 <li>some I/O cleanup and a couple of interfaces for Perl wrapper</li>
580 <li>general bug fixes</li>
581 <li>updated xmllint man page by John Fleck</li>
582 <li>some VMS and Windows updates</li>
583</ul>
584
Daniel Veillard60087f32001-10-10 09:45:09 +0000[diff] [blame]585<h3>2.4.6: Oct 10 2001</h3>
586<ul>
Daniel Veillard52dcab32001-10-30 12:51:17 +0000[diff] [blame]587 <li>added an updated man pages by John Fleck</li>
Daniel Veillard60087f32001-10-10 09:45:09 +0000[diff] [blame]588 <li>portability and configure fixes</li>
589 <li>an infinite loop on the HTML parser was removed (William)</li>
590 <li>Windows makefile patches from Igor</li>
591 <li>fixed half a dozen bugs reported fof libxml or libxslt</li>
592 <li>updated xmlcatalog to be able to modify SGML super catalogs</li>
593</ul>
594
Daniel Veillarddadd0872001-09-15 09:21:44 +0000[diff] [blame]595<h3>2.4.5: Sep 14 2001</h3>
596<ul>
597 <li>Remove a few annoying bugs in 2.4.4</li>
598 <li>forces the HTML serializer to output decimal charrefs since some
599 version of Netscape can't handle hexadecimal ones</li>
600</ul>
601
602<h3>1.8.16: Sep 14 2001</h3>
603<ul>
604 <li>maintenance release of the old libxml1 branch, couple of bug and
605 portability fixes</li>
606</ul>
607
Daniel Veillard04382ae2001-09-12 18:51:30 +0000[diff] [blame]608<h3>2.4.4: Sep 12 2001</h3>
609<ul>
610 <li>added --convert to xmlcatalog, bug fixes and cleanups of XML
611 Catalog</li>
612 <li>a few bug fixes and some portability changes</li>
613 <li>some documentation cleanups</li>
614</ul>
615
Daniel Veillard39936902001-08-24 00:49:01 +0000[diff] [blame]616<h3>2.4.3: Aug 23 2001</h3>
617<ul>
618 <li>XML Catalog support see the doc</li>
619 <li>New NaN/Infinity floating point code</li>
620 <li>A few bug fixes</li>
621</ul>
622
623<h3>2.4.2: Aug 15 2001</h3>
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]624<ul>
625 <li>adds xmlLineNumbersDefault() to control line number generation</li>
626 <li>lot of bug fixes</li>
627 <li>the Microsoft MSC projects files shuld now be up to date</li>
628 <li>inheritance of namespaces from DTD defaulted attributes</li>
629 <li>fixes a serious potential security bug</li>
630 <li>added a --format option to xmllint</li>
631</ul>
632
633<h3>2.4.1: July 24 2001</h3>
634<ul>
635 <li>possibility to keep line numbers in the tree</li>
636 <li>some computation NaN fixes</li>
637 <li>extension of the XPath API</li>
638 <li>cleanup for alpha and ia64 targets</li>
639 <li>patch to allow saving through HTTP PUT or POST</li>
Daniel Veillard09ab7e12001-07-10 15:49:44 +0000[diff] [blame]640</ul>
641
642<h3>2.4.0: July 10 2001</h3>
643<ul>
644 <li>Fixed a few bugs in XPath, validation, and tree handling.</li>
645 <li>Fixed XML Base implementation, added a coupel of examples to the
646 regression tests</li>
647 <li>A bit of cleanup</li>
Daniel Veillardab8500d2000-10-15 21:06:19 +0000[diff] [blame]648</ul>
649
Daniel Veillard5b43fde2001-07-05 23:31:40 +0000[diff] [blame]650<h3>2.3.14: July 5 2001</h3>
651<ul>
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]652 <li>fixed some entities problems and reduce mem requirement when
653 substituing them</li>
Daniel Veillard5b43fde2001-07-05 23:31:40 +0000[diff] [blame]654 <li>lots of improvements in the XPath queries interpreter can be
655 substancially faster</li>
656 <li>Makefiles and configure cleanups</li>
657 <li>Fixes to XPath variable eval, and compare on empty node set</li>
658 <li>HTML tag closing bug fixed</li>
659 <li>Fixed an URI reference computating problem when validating</li>
660</ul>
661
Daniel Veillard2adbb512001-06-28 16:20:36 +0000[diff] [blame]662<h3>2.3.13: June 28 2001</h3>
663<ul>
664 <li>2.3.12 configure.in was broken as well as the push mode XML parser</li>
665 <li>a few more fixes for compilation on Windows MSC by Yon Derek</li>
666</ul>
667
668<h3>1.8.14: June 28 2001</h3>
669<ul>
670 <li>Zbigniew Chyla gave a patch to use the old XML parser in push mode</li>
671 <li>Small Makefile fix</li>
672</ul>
673
Daniel Veillard11648102001-06-26 16:08:24 +0000[diff] [blame]674<h3>2.3.12: June 26 2001</h3>
675<ul>
676 <li>lots of cleanup</li>
677 <li>a couple of validation fix</li>
678 <li>fixed line number counting</li>
679 <li>fixed serious problems in the XInclude processing</li>
680 <li>added support for UTF8 BOM at beginning of entities</li>
681 <li>fixed a strange gcc optimizer bugs in xpath handling of float, gcc-3.0
682 miscompile uri.c (William), Thomas Leitner provided a fix for the
683 optimizer on Tru64</li>
684 <li>incorporated Yon Derek and Igor Zlatkovic fixes and improvements for
685 compilation on Windows MSC</li>
686 <li>update of libxml-doc.el (Felix Natter)</li>
687 <li>fixed 2 bugs in URI normalization code</li>
688</ul>
689
Daniel Veillarde3c81b52001-06-17 14:50:34 +0000[diff] [blame]690<h3>2.3.11: June 17 2001</h3>
691<ul>
692 <li>updates to trio, Makefiles and configure should fix some portability
693 problems (alpha)</li>
694 <li>fixed some HTML serialization problems (pre, script, and block/inline
695 handling), added encoding aware APIs, cleanup of this code</li>
696 <li>added xmlHasNsProp()</li>
697 <li>implemented a specific PI for encoding support in the DocBook SGML
698 parser</li>
699 <li>some XPath fixes (-Infinity, / as a function parameter and namespaces
700 node selection)</li>
701 <li>fixed a performance problem and an error in the validation code</li>
702 <li>fixed XInclude routine to implement the recursive behaviour</li>
703 <li>fixed xmlFreeNode problem when libxml is included statically twice</li>
704 <li>added --version to xmllint for bug reports</li>
705</ul>
706
Daniel Veillard2e4f1882001-06-01 10:11:57 +0000[diff] [blame]707<h3>2.3.10: June 1 2001</h3>
708<ul>
709 <li>fixed the SGML catalog support</li>
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]710 <li>a number of reported bugs got fixed, in XPath, iconv detection,
711 XInclude processing</li>
Daniel Veillard2e4f1882001-06-01 10:11:57 +0000[diff] [blame]712 <li>XPath string function should now handle unicode correctly</li>
713</ul>
714
Daniel Veillard4623acd2001-05-19 15:13:15 +0000[diff] [blame]715<h3>2.3.9: May 19 2001</h3>
716
717<p>Lots of bugfixes, and added a basic SGML catalog support:</p>
718<ul>
719 <li>HTML push bugfix #54891 and another patch from Jonas Borgström</li>
720 <li>some serious speed optimisation again</li>
721 <li>some documentation cleanups</li>
722 <li>trying to get better linking on solaris (-R)</li>
723 <li>XPath API cleanup from Thomas Broyer</li>
724 <li>Validation bug fixed #54631, added a patch from Gary Pennington, fixed
725 xmlValidGetValidElements()</li>
726 <li>Added an INSTALL file</li>
727 <li>Attribute removal added to API: #54433</li>
728 <li>added a basic support for SGML catalogs</li>
729 <li>fixed xmlKeepBlanksDefault(0) API</li>
730 <li>bugfix in xmlNodeGetLang()</li>
731 <li>fixed a small configure portability problem</li>
732 <li>fixed an inversion of SYSTEM and PUBLIC identifier in HTML document</li>
733</ul>
734
Daniel Veillarda265af72001-05-14 11:13:58 +0000[diff] [blame]735<h3>1.8.13: May 14 2001</h3>
736<ul>
737 <li>bugfixes release of the old libxml1 branch used by Gnome</li>
738</ul>
739
Daniel Veillard3bbbe6f2001-05-03 11:15:37 +0000[diff] [blame]740<h3>2.3.8: May 3 2001</h3>
741<ul>
742 <li>Integrated an SGML DocBook parser for the Gnome project</li>
743 <li>Fixed a few things in the HTML parser</li>
744 <li>Fixed some XPath bugs raised by XSLT use, tried to fix the floating
745 point portability issue</li>
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]746 <li>Speed improvement (8M/s for SAX, 3M/s for DOM, 1.5M/s for
747 DOM+validation using the XML REC as input and a 700MHz celeron).</li>
Daniel Veillard3bbbe6f2001-05-03 11:15:37 +0000[diff] [blame]748 <li>incorporated more Windows cleanup</li>
749 <li>added xmlSaveFormatFile()</li>
750 <li>fixed problems in copying nodes with entities references (gdome)</li>
751 <li>removed some troubles surrounding the new validation module</li>
752</ul>
753
Daniel Veillarda41123c2001-04-22 19:31:20 +0000[diff] [blame]754<h3>2.3.7: April 22 2001</h3>
755<ul>
756 <li>lots of small bug fixes, corrected XPointer</li>
757 <li>Non determinist content model validation support</li>
758 <li>added xmlDocCopyNode for gdome2</li>
759 <li>revamped the way the HTML parser handles end of tags</li>
760 <li>XPath: corrctions of namespacessupport and number formatting</li>
761 <li>Windows: Igor Zlatkovic patches for MSC compilation</li>
762 <li>HTML ouput fixes from P C Chow and William M. Brack</li>
763 <li>Improved validation speed sensible for DocBook</li>
764 <li>fixed a big bug with ID declared in external parsed entities</li>
765 <li>portability fixes, update of Trio from Bjorn Reese</li>
766</ul>
767
Daniel Veillardafc73112001-04-11 11:51:41 +0000[diff] [blame]768<h3>2.3.6: April 8 2001</h3>
769<ul>
770 <li>Code cleanup using extreme gcc compiler warning options, found and
771 cleared half a dozen potential problem</li>
772 <li>the Eazel team found an XML parser bug</li>
773 <li>cleaned up the user of some of the string formatting function. used the
774 trio library code to provide the one needed when the platform is missing
775 them</li>
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]776 <li>xpath: removed a memory leak and fixed the predicate evaluation
777 problem, extended the testsuite and cleaned up the result. XPointer seems
778 broken ...</li>
Daniel Veillardafc73112001-04-11 11:51:41 +0000[diff] [blame]779</ul>
780
Daniel Veillard56a4cb82001-03-24 17:00:36 +0000[diff] [blame]781<h3>2.3.5: Mar 23 2001</h3>
782<ul>
783 <li>Biggest change is separate parsing and evaluation of XPath expressions,
784 there is some new APIs for this too</li>
785 <li>included a number of bug fixes(XML push parser, 51876, notations,
786 52299)</li>
787 <li>Fixed some portability issues</li>
788</ul>
789
Daniel Veillarde356c282001-03-10 12:32:04 +0000[diff] [blame]790<h3>2.3.4: Mar 10 2001</h3>
791<ul>
792 <li>Fixed bugs #51860 and #51861</li>
793 <li>Added a global variable xmlDefaultBufferSize to allow default buffer
794 size to be application tunable.</li>
795 <li>Some cleanup in the validation code, still a bug left and this part
796 should probably be rewritten to support ambiguous content model :-\</li>
797 <li>Fix a couple of serious bugs introduced or raised by changes in 2.3.3
798 parser</li>
799 <li>Fixed another bug in xmlNodeGetContent()</li>
800 <li>Bjorn fixed XPath node collection and Number formatting</li>
801 <li>Fixed a loop reported in the HTML parsing</li>
802 <li>blank space are reported even if the Dtd content model proves that they
803 are formatting spaces, this is for XmL conformance</li>
804</ul>
805
Daniel Veillardb402c072001-03-01 17:28:58 +0000[diff] [blame]806<h3>2.3.3: Mar 1 2001</h3>
807<ul>
808 <li>small change in XPath for XSLT</li>
809 <li>documentation cleanups</li>
810 <li>fix in validation by Gary Pennington</li>
811 <li>serious parsing performances improvements</li>
812</ul>
813
Daniel Veillardec70e912001-02-26 20:10:45 +0000[diff] [blame]814<h3>2.3.2: Feb 24 2001</h3>
Daniel Veillard71681102001-02-24 17:48:53 +0000[diff] [blame]815<ul>
816 <li>chasing XPath bugs, found a bunch, completed some TODO</li>
817 <li>fixed a Dtd parsing bug</li>
818 <li>fixed a bug in xmlNodeGetContent</li>
819 <li>ID/IDREF support partly rewritten by Gary Pennington</li>
820</ul>
821
Daniel Veillardec70e912001-02-26 20:10:45 +0000[diff] [blame]822<h3>2.3.1: Feb 15 2001</h3>
Daniel Veillard6e6a6cc2001-02-15 15:55:44 +0000[diff] [blame]823<ul>
824 <li>some XPath and HTML bug fixes for XSLT</li>
825 <li>small extension of the hash table interfaces for DOM gdome2
826 implementation</li>
827 <li>A few bug fixes</li>
828</ul>
829
Daniel Veillardec70e912001-02-26 20:10:45 +0000[diff] [blame]830<h3>2.3.0: Feb 8 2001 (2.2.12 was on 25 Jan but I didn't kept track)</h3>
Daniel Veillard6e6a6cc2001-02-15 15:55:44 +0000[diff] [blame]831<ul>
832 <li>Lots of XPath bug fixes</li>
833 <li>Add a mode with Dtd lookup but without validation error reporting for
834 XSLT</li>
835 <li>Add support for text node without escaping (XSLT)</li>
836 <li>bug fixes for xmlCheckFilename</li>
837 <li>validation code bug fixes from Gary Pennington</li>
838 <li>Patch from Paul D. Smith correcting URI path normalization</li>
839 <li>Patch to allow simultaneous install of libxml-devel and
840 libxml2-devel</li>
841 <li>the example Makefile is now fixed</li>
842 <li>added HTML to the RPM packages</li>
843 <li>tree copying bugfixes</li>
844 <li>updates to Windows makefiles</li>
845 <li>optimisation patch from Bjorn Reese</li>
846</ul>
847
Daniel Veillardec70e912001-02-26 20:10:45 +0000[diff] [blame]848<h3>2.2.11: Jan 4 2001</h3>
Daniel Veillard503b8932001-01-05 06:36:31 +0000[diff] [blame]849<ul>
850 <li>bunch of bug fixes (memory I/O, xpath, ftp/http, ...)</li>
851 <li>added htmlHandleOmittedElem()</li>
852 <li>Applied Bjorn Reese's IPV6 first patch</li>
853 <li>Applied Paul D. Smith patches for validation of XInclude results</li>
Daniel Veillard82687162001-01-22 15:32:01 +0000[diff] [blame]854 <li>added XPointer xmlns() new scheme support</li>
Daniel Veillard503b8932001-01-05 06:36:31 +0000[diff] [blame]855</ul>
856
Daniel Veillard2ddd23d2000-11-25 10:42:19 +0000[diff] [blame]857<h3>2.2.10: Nov 25 2000</h3>
Daniel Veillard9d343c42000-11-25 10:12:43 +0000[diff] [blame]858<ul>
859 <li>Fix the Windows problems of 2.2.8</li>
860 <li>integrate OpenVMS patches</li>
861 <li>better handling of some nasty HTML input</li>
862 <li>Improved the XPointer implementation</li>
863 <li>integrate a number of provided patches</li>
864</ul>
865
Daniel Veillard2ddd23d2000-11-25 10:42:19 +0000[diff] [blame]866<h3>2.2.9: Nov 25 2000</h3>
867<ul>
868 <li>erroneous release :-(</li>
869</ul>
870
Daniel Veillard28929b22000-11-13 18:22:49 +0000[diff] [blame]871<h3>2.2.8: Nov 13 2000</h3>
872<ul>
873 <li>First version of <a href="http://www.w3.org/TR/xinclude">XInclude</a>
874 support</li>
875 <li>Patch in conditional section handling</li>
876 <li>updated MS compiler project</li>
877 <li>fixed some XPath problems</li>
878 <li>added an URI escaping function</li>
879 <li>some other bug fixes</li>
880</ul>
881
882<h3>2.2.7: Oct 31 2000</h3>
883<ul>
884 <li>added message redirection</li>
885 <li>XPath improvements (thanks TOM !)</li>
886 <li>xmlIOParseDTD() added</li>
887 <li>various small fixes in the HTML, URI, HTTP and XPointer support</li>
888 <li>some cleanup of the Makefile, autoconf and the distribution content</li>
889</ul>
890
Daniel Veillard29a11cc2000-10-25 13:32:39 +0000[diff] [blame]891<h3>2.2.6: Oct 25 2000:</h3>
892<ul>
893 <li>Added an hash table module, migrated a number of internal structure to
894 those</li>
895 <li>Fixed a posteriori validation problems</li>
896 <li>HTTP module cleanups</li>
897 <li>HTML parser improvements (tag errors, script/style handling, attribute
898 normalization)</li>
899 <li>coalescing of adjacent text nodes</li>
900 <li>couple of XPath bug fixes, exported the internal API</li>
901</ul>
902
Daniel Veillardab8500d2000-10-15 21:06:19 +0000[diff] [blame]903<h3>2.2.5: Oct 15 2000:</h3>
Daniel Veillard4c3a2031999-11-19 17:46:26 +0000[diff] [blame]904<ul>
Daniel Veillard189446d2000-10-13 10:23:06 +0000[diff] [blame]905 <li>XPointer implementation and testsuite</li>
906 <li>Lot of XPath fixes, added variable and functions registration, more
907 tests</li>
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]908 <li>Portability fixes, lots of enhancements toward an easy Windows build
909 and release</li>
Daniel Veillard189446d2000-10-13 10:23:06 +0000[diff] [blame]910 <li>Late validation fixes</li>
911 <li>Integrated a lot of contributed patches</li>
912 <li>added memory management docs</li>
Daniel Veillardab8500d2000-10-15 21:06:19 +0000[diff] [blame]913 <li>a performance problem when using large buffer seems fixed</li>
Daniel Veillard189446d2000-10-13 10:23:06 +0000[diff] [blame]914</ul>
915
916<h3>2.2.4: Oct 1 2000:</h3>
917<ul>
918 <li>main XPath problem fixed</li>
919 <li>Integrated portability patches for Windows</li>
920 <li>Serious bug fixes on the URI and HTML code</li>
Daniel Veillard361d8452000-04-03 19:48:13 +0000[diff] [blame]921</ul>
922
Daniel Veillardd5f97f82000-09-17 16:38:14 +0000[diff] [blame]923<h3>2.2.3: Sep 17 2000</h3>
924<ul>
925 <li>bug fixes</li>
926 <li>cleanup of entity handling code</li>
927 <li>overall review of all loops in the parsers, all sprintf usage has been
928 checked too</li>
929 <li>Far better handling of larges Dtd. Validating against Docbook XML Dtd
930 works smoothly now.</li>
931</ul>
932
933<h3>1.8.10: Sep 6 2000</h3>
934<ul>
935 <li>bug fix release for some Gnome projects</li>
936</ul>
937
938<h3>2.2.2: August 12 2000</h3>
Daniel Veillard786d7c82000-08-12 23:38:57 +0000[diff] [blame]939<ul>
940 <li>mostly bug fixes</li>
Daniel Veillardec78c0f2000-08-25 10:25:23 +0000[diff] [blame]941 <li>started adding routines to access xml parser context options</li>
Daniel Veillard786d7c82000-08-12 23:38:57 +0000[diff] [blame]942</ul>
943
Daniel Veillardd5f97f82000-09-17 16:38:14 +0000[diff] [blame]944<h3>2.2.1: July 21 2000</h3>
Daniel Veillarda2679fa2000-07-22 02:38:15 +0000[diff] [blame]945<ul>
946 <li>a purely bug fixes release</li>
947 <li>fixed an encoding support problem when parsing from a memory block</li>
948 <li>fixed a DOCTYPE parsing problem</li>
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]949 <li>removed a bug in the function allowing to override the memory
950 allocation routines</li>
Daniel Veillarda2679fa2000-07-22 02:38:15 +0000[diff] [blame]951</ul>
952
Daniel Veillardd5f97f82000-09-17 16:38:14 +0000[diff] [blame]953<h3>2.2.0: July 14 2000</h3>
Daniel Veillard94e90602000-07-17 14:38:19 +0000[diff] [blame]954<ul>
955 <li>applied a lot of portability fixes</li>
956 <li>better encoding support/cleanup and saving (content is now always
957 encoded in UTF-8)</li>
958 <li>the HTML parser now correctly handles encodings</li>
959 <li>added xmlHasProp()</li>
960 <li>fixed a serious problem with &amp;#38;</li>
961 <li>propagated the fix to FTP client</li>
962 <li>cleanup, bugfixes, etc ...</li>
963 <li>Added a page about <a href="encoding.html">libxml Internationalization
964 support</a></li>
965</ul>
966
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]967<h3>1.8.9: July 9 2000</h3>
968<ul>
969 <li>fixed the spec the RPMs should be better</li>
970 <li>fixed a serious bug in the FTP implementation, released 1.8.9 to solve
971 rpmfind users problem</li>
972</ul>
973
Daniel Veillard6388e172000-07-03 16:07:19 +0000[diff] [blame]974<h3>2.1.1: July 1 2000</h3>
975<ul>
976 <li>fixes a couple of bugs in the 2.1.0 packaging</li>
977 <li>improvements on the HTML parser</li>
978</ul>
979
Daniel Veillard3f6f7f62000-06-30 17:58:25 +0000[diff] [blame]980<h3>2.1.0 and 1.8.8: June 29 2000</h3>
981<ul>
982 <li>1.8.8 is mostly a comodity package for upgrading to libxml2 accoding to
983 <a href="upgrade.html">new instructions</a>. It fixes a nasty problem
984 about &amp;#38; charref parsing</li>
985 <li>2.1.0 also ease the upgrade from libxml v1 to the recent version. it
986 also contains numerous fixes and enhancements:
987 <ul>
988 <li>added xmlStopParser() to stop parsing</li>
989 <li>improved a lot parsing speed when there is large CDATA blocs</li>
990 <li>includes XPath patches provided by Picdar Technology</li>
991 <li>tried to fix as much as possible DtD validation and namespace
992 related problems</li>
993 <li>output to a given encoding has been added/tested</li>
994 <li>lot of various fixes</li>
995 </ul>
996 </li>
997</ul>
998
Daniel Veillarde0aed302000-04-16 08:52:20 +0000[diff] [blame]999<h3>2.0.0: Apr 12 2000</h3>
Daniel Veillard361d8452000-04-03 19:48:13 +0000[diff] [blame]1000<ul>
1001 <li>First public release of libxml2. If you are using libxml, it's a good
Daniel Veillarde0aed302000-04-16 08:52:20 +0000[diff] [blame]1002 idea to check the 1.x to 2.x upgrade instructions. NOTE: while initally
1003 scheduled for Apr 3 the relase occured only on Apr 12 due to massive
1004 workload.</li>
Daniel Veillard361d8452000-04-03 19:48:13 +0000[diff] [blame]1005 <li>The include are now located under $prefix/include/libxml (instead of
Daniel Veillarde0aed302000-04-16 08:52:20 +0000[diff] [blame]1006 $prefix/include/gnome-xml), they also are referenced by
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]1007 <pre>#include &lt;libxml/xxx.h&gt;</pre>
Daniel Veillarde0aed302000-04-16 08:52:20 +0000[diff] [blame]1008 <p>instead of</p>
Daniel Veillard361d8452000-04-03 19:48:13 +0000[diff] [blame]1009 <pre>#include "xxx.h"</pre>
1010 </li>
Daniel Veillard8f621982000-03-20 13:07:15 +0000[diff] [blame]1011 <li>a new URI module for parsing URIs and following strictly RFC 2396</li>
1012 <li>the memory allocation routines used by libxml can now be overloaded
1013 dynamically by using xmlMemSetup()</li>
Daniel Veillard361d8452000-04-03 19:48:13 +0000[diff] [blame]1014 <li>The previously CVS only tool tester has been renamed
1015 <strong>xmllint</strong> and is now installed as part of the libxml2
1016 package</li>
Daniel Veillarde0aed302000-04-16 08:52:20 +0000[diff] [blame]1017 <li>The I/O interface has been revamped. There is now ways to plug in
1018 specific I/O modules, either at the URI scheme detection level using
1019 xmlRegisterInputCallbacks() or by passing I/O functions when creating a
1020 parser context using xmlCreateIOParserCtxt()</li>
1021 <li>there is a C preprocessor macro LIBXML_VERSION providing the version
1022 number of the libxml module in use</li>
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]1023 <li>a number of optional features of libxml can now be excluded at
1024 configure time (FTP/HTTP/HTML/XPath/Debug)</li>
Daniel Veillardedfb29b2000-03-14 19:59:05 +0000[diff] [blame]1025</ul>
1026
1027<h3>2.0.0beta: Mar 14 2000</h3>
1028<ul>
1029 <li>This is a first Beta release of libxml version 2</li>
Daniel Veillarde356c282001-03-10 12:32:04 +0000[diff] [blame]1030 <li>It's available only from<a href="ftp://xmlsoft.org/">xmlsoft.org
1031 FTP</a>, it's packaged as libxml2-2.0.0beta and available as tar and
1032 RPMs</li>
Daniel Veillardedfb29b2000-03-14 19:59:05 +0000[diff] [blame]1033 <li>This version is now the head in the Gnome CVS base, the old one is
1034 available under the tag LIB_XML_1_X</li>
1035 <li>This includes a very large set of changes. Froma programmatic point of
1036 view applications should not have to be modified too much, check the <a
1037 href="upgrade.html">upgrade page</a></li>
1038 <li>Some interfaces may changes (especially a bit about encoding).</li>
1039 <li>the updates includes:
Daniel Veillard6c8b1172000-03-01 00:40:41 +0000[diff] [blame]1040 <ul>
Daniel Veillardedfb29b2000-03-14 19:59:05 +0000[diff] [blame]1041 <li>fix I18N support. ISO-Latin-x/UTF-8/UTF-16 (nearly) seems correctly
1042 handled now</li>
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]1043 <li>Better handling of entities, especially well formedness checking
1044 and proper PEref extensions in external subsets</li>
Daniel Veillard6c8b1172000-03-01 00:40:41 +0000[diff] [blame]1045 <li>DTD conditional sections</li>
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]1046 <li>Validation now correcly handle entities content</li>
Daniel Veillard6c8b1172000-03-01 00:40:41 +0000[diff] [blame]1047 <li><a href="http://rpmfind.net/tools/gdome/messages/0039.html">change
1048 structures to accomodate DOM</a></li>
Daniel Veillard6c8b1172000-03-01 00:40:41 +0000[diff] [blame]1049 </ul>
1050 </li>
Daniel Veillardedfb29b2000-03-14 19:59:05 +0000[diff] [blame]1051 <li>Serious progress were made toward compliance, <a
1052 href="conf/result.html">here are the result of the test</a> against the
1053 OASIS testsuite (except the japanese tests since I don't support that
1054 encoding yet). This URL is rebuilt every couple of hours using the CVS
1055 head version.</li>
Daniel Veillarde41f2b72000-01-30 20:00:07 +0000[diff] [blame]1056</ul>
1057
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]1058<h3>1.8.7: Mar 6 2000</h3>
1059<ul>
1060 <li>This is a bug fix release:</li>
1061 <li>It is possible to disable the ignorable blanks heuristic used by
1062 libxml-1.x, a new function xmlKeepBlanksDefault(0) will allow this. Note
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]1063 that for adherence to XML spec, this behaviour will be disabled by
1064 default in 2.x . The same function will allow to keep compatibility for
1065 old code.</li>
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]1066 <li>Blanks in &lt;a&gt; &lt;/a&gt; constructs are not ignored anymore,
1067 avoiding heuristic is really the Right Way :-\</li>
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]1068 <li>The unchecked use of snprintf which was breaking libxml-1.8.6
1069 compilation on some platforms has been fixed</li>
1070 <li>nanoftp.c nanohttp.c: Fixed '#' and '?' stripping when processing
1071 URIs</li>
1072</ul>
1073
Daniel Veillarde41f2b72000-01-30 20:00:07 +0000[diff] [blame]1074<h3>1.8.6: Jan 31 2000</h3>
1075<ul>
1076 <li>added a nanoFTP transport module, debugged until the new version of <a
1077 href="http://rpmfind.net/linux/rpm2html/rpmfind.html">rpmfind</a> can use
1078 it without troubles</li>
Daniel Veillardda07c342000-01-25 18:31:22 +0000[diff] [blame]1079</ul>
1080
1081<h3>1.8.5: Jan 21 2000</h3>
1082<ul>
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]1083 <li>adding APIs to parse a well balanced chunk of XML (production <a
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]1084 href="http://www.w3.org/TR/REC-xml#NT-content">[43] content</a> of the
1085 XML spec)</li>
Daniel Veillard461a66c2000-01-18 18:01:01 +0000[diff] [blame]1086 <li>fixed a hideous bug in xmlGetProp pointed by Rune.Djurhuus@fast.no</li>
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]1087 <li>Jody Goldberg &lt;jgoldberg@home.com&gt; provided another patch trying
1088 to solve the zlib checks problems</li>
Daniel Veillard461a66c2000-01-18 18:01:01 +0000[diff] [blame]1089 <li>The current state in gnome CVS base is expected to ship as 1.8.5 with
1090 gnumeric soon</li>
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]1091</ul>
1092
1093<h3>1.8.4: Jan 13 2000</h3>
1094<ul>
1095 <li>bug fixes, reintroduced xmlNewGlobalNs(), fixed xmlNewNs()</li>
1096 <li>all exit() call should have been removed from libxml</li>
1097 <li>fixed a problem with INCLUDE_WINSOCK on WIN32 platform</li>
1098 <li>added newDocFragment()</li>
Daniel Veillardf84f71f2000-01-05 19:54:23 +0000[diff] [blame]1099</ul>
1100
1101<h3>1.8.3: Jan 5 2000</h3>
1102<ul>
1103 <li>a Push interface for the XML and HTML parsers</li>
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]1104 <li>a shell-like interface to the document tree (try tester --shell :-)</li>
Daniel Veillarddbfd6411999-12-28 16:35:14 +0000[diff] [blame]1105 <li>lots of bug fixes and improvement added over XMas hollidays</li>
Daniel Veillard437b87b2000-01-03 17:30:46 +0000[diff] [blame]1106 <li>fixed the DTD parsing code to work with the xhtml DTD</li>
Daniel Veillardf84f71f2000-01-05 19:54:23 +0000[diff] [blame]1107 <li>added xmlRemoveProp(), xmlRemoveID() and xmlRemoveRef()</li>
1108 <li>Fixed bugs in xmlNewNs()</li>
Daniel Veillard437b87b2000-01-03 17:30:46 +0000[diff] [blame]1109 <li>External entity loading code has been revamped, now it uses
Daniel Veillardf84f71f2000-01-05 19:54:23 +0000[diff] [blame]1110 xmlLoadExternalEntity(), some fix on entities processing were added</li>
Daniel Veillard437b87b2000-01-03 17:30:46 +0000[diff] [blame]1111 <li>cleaned up WIN32 includes of socket stuff</li>
Daniel Veillard5cb5ab81999-12-21 15:35:29 +0000[diff] [blame]1112</ul>
1113
1114<h3>1.8.2: Dec 21 1999</h3>
1115<ul>
Daniel Veillardb24054a1999-12-18 15:32:46 +0000[diff] [blame]1116 <li>I got another problem with includes and C++, I hope this issue is fixed
1117 for good this time</li>
Daniel Veillard5cb5ab81999-12-21 15:35:29 +0000[diff] [blame]1118 <li>Added a few tree modification functions: xmlReplaceNode,
1119 xmlAddPrevSibling, xmlAddNextSibling, xmlNodeSetName and
1120 xmlDocSetRootElement</li>
1121 <li>Tried to improve the HTML output with help from <a
1122 href="mailto:clahey@umich.edu">Chris Lahey</a></li>
Daniel Veillarde4e51311999-12-18 15:32:46 +0000[diff] [blame]1123</ul>
Daniel Veillardb24054a1999-12-18 15:32:46 +0000[diff] [blame]1124
Daniel Veillarde4e51311999-12-18 15:32:46 +0000[diff] [blame]1125<h3>1.8.1: Dec 18 1999</h3>
1126<ul>
1127 <li>various patches to avoid troubles when using libxml with C++ compilers
1128 the "namespace" keyword and C escaping in include files</li>
1129 <li>a problem in one of the core macros IS_CHAR was corrected</li>
1130 <li>fixed a bug introduced in 1.8.0 breaking default namespace processing,
1131 and more specifically the Dia application</li>
Daniel Veillard944b5ff1999-12-15 19:08:24 +0000[diff] [blame]1132 <li>fixed a posteriori validation (validation after parsing, or by using a
1133 Dtd not specified in the original document)</li>
Daniel Veillardb24054a1999-12-18 15:32:46 +0000[diff] [blame]1134 <li>fixed a bug in</li>
Daniel Veillard10a2c651999-12-12 13:03:50 +0000[diff] [blame]1135</ul>
1136
1137<h3>1.8.0: Dec 12 1999</h3>
1138<ul>
1139 <li>cleanup, especially memory wise</li>
1140 <li>the parser should be more reliable, especially the HTML one, it should
1141 not crash, whatever the input !</li>
1142 <li>Integrated various patches, especially a speedup improvement for large
1143 dataset from <a href="mailto:cnygard@bellatlantic.net">Carl Nygard</a>,
1144 configure with --with-buffers to enable them.</li>
1145 <li>attribute normalization, oops should have been added long ago !</li>
1146 <li>attributes defaulted from Dtds should be available, xmlSetProp() now
1147 does entities escapting by default.</li>
Daniel Veillard4c3a2031999-11-19 17:46:26 +0000[diff] [blame]1148</ul>
Daniel Veillard35008381999-10-25 13:15:52 +0000[diff] [blame]1149
1150<h3>1.7.4: Oct 25 1999</h3>
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]1151<ul>
Daniel Veillard35008381999-10-25 13:15:52 +0000[diff] [blame]1152 <li>Lots of HTML improvement</li>
1153 <li>Fixed some errors when saving both XML and HTML</li>
1154 <li>More examples, the regression tests should now look clean</li>
1155 <li>Fixed a bug with contiguous charref</li>
1156</ul>
1157
1158<h3>1.7.3: Sep 29 1999</h3>
1159<ul>
1160 <li>portability problems fixed</li>
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]1161 <li>snprintf was used unconditionnally, leading to link problems on system
Daniel Veillard35008381999-10-25 13:15:52 +0000[diff] [blame]1162 were it's not available, fixed</li>
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]1163</ul>
1164
1165<h3>1.7.1: Sep 24 1999</h3>
1166<ul>
1167 <li>The basic type for strings manipulated by libxml has been renamed in
1168 1.7.1 from <strong>CHAR</strong> to <strong>xmlChar</strong>. The reason
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]1169 is that CHAR was conflicting with a predefined type on Windows. However
1170 on non WIN32 environment, compatibility is provided by the way of a
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]1171 <strong>#define </strong>.</li>
1172 <li>Changed another error : the use of a structure field called errno, and
1173 leading to troubles on platforms where it's a macro</li>
1174</ul>
1175
1176<h3>1.7.0: sep 23 1999</h3>
1177<ul>
1178 <li>Added the ability to fetch remote DTD or parsed entities, see the <a
Daniel Veillard9cb5ff42001-01-29 08:22:21 +0000[diff] [blame]1179 href="html/libxml-nanohttp.html">nanohttp</a> module.</li>
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]1180 <li>Added an errno to report errors by another mean than a simple printf
1181 like callback</li>
1182 <li>Finished ID/IDREF support and checking when validation</li>
1183 <li>Serious memory leaks fixed (there is now a <a
Daniel Veillard9cb5ff42001-01-29 08:22:21 +0000[diff] [blame]1184 href="html/libxml-xmlmemory.html">memory wrapper</a> module)</li>
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]1185 <li>Improvement of <a href="http://www.w3.org/TR/xpath">XPath</a>
1186 implementation</li>
1187 <li>Added an HTML parser front-end</li>
1188</ul>
1189
1190<h2><a name="XML">XML</a></h2>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]1191
Daniel Veillard402e8c82000-02-29 22:57:47 +0000[diff] [blame]1192<p><a href="http://www.w3.org/TR/REC-xml">XML is a standard</a> for
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]1193markup-based structured documents. Here is <a name="example">an example XML
1194document</a>:</p>
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]1195<pre>&lt;?xml version="1.0"?&gt;
1196&lt;EXAMPLE prop1="gnome is great" prop2="&amp;amp; linux too"&gt;
1197 &lt;head&gt;
1198 &lt;title&gt;Welcome to Gnome&lt;/title&gt;
1199 &lt;/head&gt;
1200 &lt;chapter&gt;
1201 &lt;title&gt;The Linux adventure&lt;/title&gt;
1202 &lt;p&gt;bla bla bla ...&lt;/p&gt;
1203 &lt;image href="linus.gif"/&gt;
1204 &lt;p&gt;...&lt;/p&gt;
1205 &lt;/chapter&gt;
1206&lt;/EXAMPLE&gt;</pre>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]1207
Daniel Veillard402e8c82000-02-29 22:57:47 +0000[diff] [blame]1208<p>The first line specifies that it's an XML document and gives useful
1209information about its encoding. Then the document is a text format whose
1210structure is specified by tags between brackets. <strong>Each tag opened has
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]1211to be closed</strong>. XML is pedantic about this. However, if a tag is empty
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]1212(no content), a single tag can serve as both the opening and closing tag if
1213it ends with <code>/&gt;</code> rather than with <code>&gt;</code>. Note
1214that, for example, the image tag has no content (just an attribute) and is
1215closed by ending the tag with <code>/&gt;</code>.</p>
Daniel Veillardccb09631998-10-27 06:21:04 +0000[diff] [blame]1216
Daniel Veillard402e8c82000-02-29 22:57:47 +0000[diff] [blame]1217<p>XML can be applied sucessfully to a wide range of uses, from long term
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]1218structured document maintenance (where it follows the steps of SGML) to
1219simple data encoding mechanisms like configuration file formatting (glade),
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]1220spreadsheets (gnumeric), or even shorter lived documents such as WebDAV where
1221it is used to encode remote calls between a client and a server.</p>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]1222
Daniel Veillard82687162001-01-22 15:32:01 +0000[diff] [blame]1223<h2><a name="XSLT">XSLT</a></h2>
1224
Daniel Veillard6e6a6cc2001-02-15 15:55:44 +0000[diff] [blame]1225<p>Check <a href="http://xmlsoft.org/XSLT">the separate libxslt page</a></p>
1226
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]1227<p><a href="http://www.w3.org/TR/xslt">XSL Transformations</a>, is a
1228language for transforming XML documents into other XML documents (or
1229HTML/textual output).</p>
Daniel Veillard82687162001-01-22 15:32:01 +0000[diff] [blame]1230
1231<p>A separate library called libxslt is being built on top of libxml2. This
1232module "libxslt" can be found in the Gnome CVS base too.</p>
1233
Daniel Veillard383b1472001-01-23 11:39:52 +0000[diff] [blame]1234<p>You can check the <a
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]1235href="http://cvs.gnome.org/lxr/source/libxslt/FEATURES">features</a>
1236supported and the progresses on the <a
Daniel Veillard82687162001-01-22 15:32:01 +0000[diff] [blame]1237href="http://cvs.gnome.org/lxr/source/libxslt/ChangeLog">Changelog</a></p>
1238
Daniel Veillardb8cfbd12001-10-25 10:53:28 +0000[diff] [blame]1239<h2><a name="architecture">libxml architecture</a></h2>
Daniel Veillard4540be42000-08-19 16:40:28 +0000[diff] [blame]1240
Daniel Veillardec70e912001-02-26 20:10:45 +0000[diff] [blame]1241<p>Libxml is made of multiple components; some of them are optional, and most
1242of the block interfaces are public. The main components are:</p>
Daniel Veillard4540be42000-08-19 16:40:28 +0000[diff] [blame]1243<ul>
1244 <li>an Input/Output layer</li>
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]1245 <li>FTP and HTTP client layers (optional)</li>
Daniel Veillard4540be42000-08-19 16:40:28 +0000[diff] [blame]1246 <li>an Internationalization layer managing the encodings support</li>
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]1247 <li>a URI module</li>
Daniel Veillard4540be42000-08-19 16:40:28 +0000[diff] [blame]1248 <li>the XML parser and its basic SAX interface</li>
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]1249 <li>an HTML parser using the same SAX interface (optional)</li>
Daniel Veillard4540be42000-08-19 16:40:28 +0000[diff] [blame]1250 <li>a SAX tree module to build an in-memory DOM representation</li>
1251 <li>a tree module to manipulate the DOM representation</li>
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]1252 <li>a validation module using the DOM representation (optional)</li>
Daniel Veillard4540be42000-08-19 16:40:28 +0000[diff] [blame]1253 <li>an XPath module for global lookup in a DOM representation
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]1254 (optional)</li>
1255 <li>a debug module (optional)</li>
Daniel Veillard4540be42000-08-19 16:40:28 +0000[diff] [blame]1256</ul>
1257
1258<p>Graphically this gives the following:</p>
1259
1260<p><img src="libxml.gif" alt="a graphical view of the various"></p>
1261
1262<p></p>
1263
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]1264<h2><a name="tree">The tree output</a></h2>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]1265
1266<p>The parser returns a tree built during the document analysis. The value
Daniel Veillard402e8c82000-02-29 22:57:47 +0000[diff] [blame]1267returned is an <strong>xmlDocPtr</strong> (i.e., a pointer to an
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]1268<strong>xmlDoc</strong> structure). This structure contains information such
Daniel Veillard306be992000-07-03 12:38:45 +0000[diff] [blame]1269as the file name, the document type, and a <strong>children</strong> pointer
1270which is the root of the document (or more exactly the first child under the
1271root which is the document). The tree is made of <strong>xmlNode</strong>s,
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]1272chained in double-linked lists of siblings and with a children&lt;-&gt;parent
Daniel Veillard306be992000-07-03 12:38:45 +0000[diff] [blame]1273relationship. An xmlNode can also carry properties (a chain of xmlAttr
1274structures). An attribute may have a value which is a list of TEXT or
1275ENTITY_REF nodes.</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]1276
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]1277<p>Here is an example (erroneous with respect to the XML spec since there
1278should be only one ELEMENT under the root):</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]1279
1280<p><img src="structure.gif" alt=" structure.gif "></p>
1281
1282<p>In the source package there is a small program (not installed by default)
Daniel Veillard361d8452000-04-03 19:48:13 +0000[diff] [blame]1283called <strong>xmllint</strong> which parses XML files given as argument and
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]1284prints them back as parsed. This is useful for detecting errors both in XML
1285code and in the XML parser itself. It has an option <strong>--debug</strong>
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]1286which prints the actual in-memory structure of the document; here is the
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]1287result with the <a href="#example">example</a> given before:</p>
Daniel Veillard10c6a8f1998-10-28 01:00:12 +0000[diff] [blame]1288<pre>DOCUMENT
1289version=1.0
1290standalone=true
1291 ELEMENT EXAMPLE
1292 ATTRIBUTE prop1
1293 TEXT
1294 content=gnome is great
1295 ATTRIBUTE prop2
1296 ENTITY_REF
1297 TEXT
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]1298 content= linux too
Daniel Veillard402e8c82000-02-29 22:57:47 +0000[diff] [blame]1299 ELEMENT head
Daniel Veillard10c6a8f1998-10-28 01:00:12 +0000[diff] [blame]1300 ELEMENT title
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]1301 TEXT
1302 content=Welcome to Gnome
Daniel Veillard10c6a8f1998-10-28 01:00:12 +0000[diff] [blame]1303 ELEMENT chapter
1304 ELEMENT title
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]1305 TEXT
1306 content=The Linux adventure
Daniel Veillard10c6a8f1998-10-28 01:00:12 +0000[diff] [blame]1307 ELEMENT p
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]1308 TEXT
1309 content=bla bla bla ...
Daniel Veillard10c6a8f1998-10-28 01:00:12 +0000[diff] [blame]1310 ELEMENT image
1311 ATTRIBUTE href
1312 TEXT
1313 content=linus.gif
1314 ELEMENT p
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]1315 TEXT
1316 content=...</pre>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]1317
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]1318<p>This should be useful for learning the internal representation model.</p>
Daniel Veillardccb09631998-10-27 06:21:04 +0000[diff] [blame]1319
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]1320<h2><a name="interface">The SAX interface</a></h2>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]1321
Daniel Veillard402e8c82000-02-29 22:57:47 +0000[diff] [blame]1322<p>Sometimes the DOM tree output is just too large to fit reasonably into
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]1323memory. In that case (and if you don't expect to save back the XML document
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]1324loaded using libxml), it's better to use the SAX interface of libxml. SAX is
1325a <strong>callback-based interface</strong> to the parser. Before parsing,
1326the application layer registers a customized set of callbacks which are
1327called by the library as it progresses through the XML input.</p>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]1328
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]1329<p>To get more detailed step-by-step guidance on using the SAX interface of
Daniel Veillard4540be42000-08-19 16:40:28 +0000[diff] [blame]1330libxml, see the <a
1331href="http://www.daa.com.au/~james/gnome/xml-sax/xml-sax.html">nice
1332documentation</a>.written by <a href="mailto:james@daa.com.au">James
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]1333Henstridge</a>.</p>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]1334
1335<p>You can debug the SAX behaviour by using the <strong>testSAX</strong>
1336program located in the gnome-xml module (it's usually not shipped in the
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]1337binary packages of libxml, but you can find it in the tar source
Daniel Veillard402e8c82000-02-29 22:57:47 +0000[diff] [blame]1338distribution). Here is the sequence of callbacks that would be reported by
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]1339testSAX when parsing the example XML document shown earlier:</p>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]1340<pre>SAX.setDocumentLocator()
1341SAX.startDocument()
1342SAX.getEntity(amp)
1343SAX.startElement(EXAMPLE, prop1='gnome is great', prop2='&amp;amp; linux too')
1344SAX.characters( , 3)
1345SAX.startElement(head)
1346SAX.characters( , 4)
1347SAX.startElement(title)
1348SAX.characters(Welcome to Gnome, 16)
1349SAX.endElement(title)
1350SAX.characters( , 3)
1351SAX.endElement(head)
1352SAX.characters( , 3)
1353SAX.startElement(chapter)
1354SAX.characters( , 4)
1355SAX.startElement(title)
1356SAX.characters(The Linux adventure, 19)
1357SAX.endElement(title)
1358SAX.characters( , 4)
1359SAX.startElement(p)
1360SAX.characters(bla bla bla ..., 15)
1361SAX.endElement(p)
1362SAX.characters( , 4)
1363SAX.startElement(image, href='linus.gif')
1364SAX.endElement(image)
1365SAX.characters( , 4)
1366SAX.startElement(p)
1367SAX.characters(..., 3)
1368SAX.endElement(p)
1369SAX.characters( , 3)
1370SAX.endElement(chapter)
1371SAX.characters( , 1)
1372SAX.endElement(EXAMPLE)
1373SAX.endDocument()</pre>
1374
Daniel Veillardec70e912001-02-26 20:10:45 +0000[diff] [blame]1375<p>Most of the other interfaces of libxml are based on the DOM tree-building
1376facility, so nearly everything up to the end of this document presupposes the
1377use of the standard DOM tree build. Note that the DOM tree itself is built by
1378a set of registered default callbacks, without internal specific
1379interface.</p>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]1380
Daniel Veillardb8cfbd12001-10-25 10:53:28 +0000[diff] [blame]1381<h2><a name="Validation">Validation &amp; DTDs</a></h2>
1382
1383<p>Table of Content:</p>
1384<ol>
1385 <li><a href="#General5">General overview</a></li>
1386 <li><a href="#definition">The definition</a></li>
1387 <li><a href="#Simple">Simple rules</a>
1388 <ol>
Daniel Veillard9c466822001-10-25 12:03:39 +0000[diff] [blame]1389 <li><a href="#reference">How to reference a DTD from a document</a></li>
Daniel Veillardb8cfbd12001-10-25 10:53:28 +0000[diff] [blame]1390 <li><a href="#Declaring">Declaring elements</a></li>
1391 <li><a href="#Declaring1">Declaring attributes</a></li>
1392 </ol>
1393 </li>
1394 <li><a href="#Some">Some examples</a></li>
1395 <li><a href="#validate">How to validate</a></li>
1396 <li><a href="#Other">Other resources</a></li>
1397</ol>
1398
1399<h3><a name="General5">General overview</a></h3>
1400
1401<p>Well what is validation and what is a DTD ?</p>
1402
1403<p>DTD is the acronym for Document Type Definition. This is a description of
1404the content for a familly of XML files. This is part of the XML 1.0
1405specification, and alows to describe and check that a given document instance
1406conforms to a set of rules detailing its structure and content.</p>
1407
1408<p>Validation is the process of checking a document against a DTD (more
1409generally against a set of construction rules).</p>
1410
1411<p>The validation process and building DTDs are the two most difficult parts
1412of the XML life cycle. Briefly a DTD defines all the possibles element to be
1413found within your document, what is the formal shape of your document tree
1414(by defining the allowed content of an element, either text, a regular
1415expression for the allowed list of children, or mixed content i.e. both text
1416and children). The DTD also defines the allowed attributes for all elements
1417and the types of the attributes.</p>
1418
1419<h3><a name="definition1">The definition</a></h3>
1420
1421<p>The <a href="http://www.w3.org/TR/REC-xml">W3C XML Recommendation</a> (<a
1422href="http://www.xml.com/axml/axml.html">Tim Bray's annotated version of
1423Rev1</a>):</p>
1424<ul>
1425 <li><a href="http://www.w3.org/TR/REC-xml#elemdecls">Declaring
1426 elements</a></li>
1427 <li><a href="http://www.w3.org/TR/REC-xml#attdecls">Declaring
1428 attributes</a></li>
1429</ul>
1430
1431<p>(unfortunately) all this is inherited from the SGML world, the syntax is
1432ancient...</p>
1433
1434<h3><a name="Simple1">Simple rules</a></h3>
1435
1436<p>Writing DTD can be done in multiple ways, the rules to build them if you
1437need something fixed or something which can evolve over time can be radically
1438different. Really complex DTD like Docbook ones are flexible but quite harder
1439to design. I will just focuse on DTDs for a formats with a fixed simple
1440structure. It is just a set of basic rules, and definitely not exhaustive nor
1441useable for complex DTD design.</p>
1442
1443<h4><a name="reference1">How to reference a DTD from a document</a>:</h4>
1444
1445<p>Assuming the top element of the document is <code>spec</code> and the dtd
1446is placed in the file <code>mydtd</code> in the subdirectory
1447<code>dtds</code> of the directory from where the document were loaded:</p>
1448
1449<p><code>&lt;!DOCTYPE spec SYSTEM "dtds/mydtd"&gt;</code></p>
1450
1451<p>Notes:</p>
1452<ul>
1453 <li>the system string is actually an URI-Reference (as defined in <a
1454 href="http://www.ietf.org/rfc/rfc2396.txt">RFC 2396</a>) so you can use a
1455 full URL string indicating the location of your DTD on the Web, this is a
1456 really good thing to do if you want others to validate your document</li>
1457 <li>it is also possible to associate a <code>PUBLIC</code> identifier (a
1458 magic string) so that the DTd is looked up in catalogs on the client side
1459 without having to locate it on the web</li>
1460 <li>a dtd contains a set of elements and attributes declarations, but they
1461 don't define what the root of the document should be. This is explicitely
1462 told to the parser/validator as the first element of the
1463 <code>DOCTYPE</code> declaration.</li>
1464</ul>
1465
1466<h4><a name="Declaring2">Declaring elements</a>:</h4>
1467
1468<p>The following declares an element <code>spec</code>:</p>
1469
1470<p><code>&lt;!ELEMENT spec (front, body, back?)&gt;</code></p>
1471
1472<p>it also expresses that the spec element contains one <code>front</code>,
1473one <code>body</code> and one optionnal <code>back</code> children elements
1474in this order. The declaration of one element of the structure and its
1475content are done in a single declaration. Similary the following declares
1476<code>div1</code> elements:</p>
1477
1478<p><code>&lt;!ELEMENT div1 (head, (p | list | note)*, div2*)&gt;</code></p>
1479
1480<p>means div1 contains one <code>head</code> then a series of optional
1481<code>p</code>, <code>list</code>s and <code>note</code>s and then an
1482optional <code>div2</code>. And last but not least an element can contain
1483text:</p>
1484
1485<p><code>&lt;!ELEMENT b (#PCDATA)&gt;</code></p>
1486
1487<p><code>b</code> contains text or being of mixed content (text and elements
1488in no particular order):</p>
1489
1490<p><code>&lt;!ELEMENT p (#PCDATA|a|ul|b|i|em)*&gt;</code></p>
1491
1492<p><code>p </code>can contain text or <code>a</code>, <code>ul</code>,
1493<code>b</code>, <code>i </code>or <code>em</code> elements in no particular
1494order.</p>
1495
1496<h4><a name="Declaring1">Declaring attributes</a>:</h4>
1497
1498<p>again the attributes declaration includes their content definition:</p>
1499
1500<p><code>&lt;!ATTLIST termdef name CDATA #IMPLIED&gt;</code></p>
1501
1502<p>means that the element <code>termdef</code> can have a <code>name</code>
1503attribute containing text (<code>CDATA</code>) and which is optionnal
1504(<code>#IMPLIED</code>). The attribute value can also be defined within a
1505set:</p>
1506
1507<p><code>&lt;!ATTLIST list type (bullets|ordered|glossary)
1508"ordered"&gt;</code></p>
1509
1510<p>means <code>list</code> element have a <code>type</code> attribute with 3
1511allowed values "bullets", "ordered" or "glossary" and which default to
1512"ordered" if the attribute is not explicitely specified.</p>
1513
1514<p>The content type of an attribute can be text (<code>CDATA</code>),
1515anchor/reference/references
1516(<code>ID</code>/<code>IDREF</code>/<code>IDREFS</code>), entity(ies)
1517(<code>ENTITY</code>/<code>ENTITIES</code>) or name(s)
1518(<code>NMTOKEN</code>/<code>NMTOKENS</code>). The following defines that a
1519<code>chapter</code> element can have an optional <code>id</code> attribute
1520of type <code>ID</code>, usable for reference from attribute of type
1521IDREF:</p>
1522
1523<p><code>&lt;!ATTLIST chapter id ID #IMPLIED&gt;</code></p>
1524
1525<p>The last value of an attribute definition can be <code>#REQUIRED
1526</code>meaning that the attribute has to be given, <code>#IMPLIED</code>
1527meaning that it is optional, or the default value (possibly prefixed by
1528<code>#FIXED</code> if it is the only allowed).</p>
1529
1530<p>Notes:</p>
1531<ul>
1532 <li>usually the attributes pertaining to a given element are declared in a
1533 single expression, but it is just a convention adopted by a lot of DTD
1534 writers:
1535 <pre>&lt;!ATTLIST termdef
1536 id ID #REQUIRED
1537 name CDATA #IMPLIED&gt;</pre>
1538 <p>The previous construct defines both <code>id</code> and
1539 <code>name</code> attributes for the element <code>termdef</code></p>
1540 </li>
1541</ul>
1542
1543<h3><a name="Some1">Some examples</a></h3>
1544
1545<p>The directory <code>test/valid/dtds/</code> in the libxml distribution
1546contains some complex DTD examples. The <code>test/valid/dia.xml</code>
1547example shows an XML file where the simple DTD is directly included within
1548the document.</p>
1549
1550<h3><a name="validate1">How to validate</a></h3>
1551
1552<p>The simplest is to use the xmllint program comming with libxml. The
1553<code>--valid</code> option turn on validation of the files given as input,
1554for example the following validates a copy of the first revision of the XML
15551.0 specification:</p>
1556
1557<p><code>xmllint --valid --noout test/valid/REC-xml-19980210.xml</code></p>
1558
1559<p>the -- noout is used to not output the resulting tree.</p>
1560
1561<p>The <code>--dtdvalid dtd</code> allows to validate the document(s) against
1562a given DTD.</p>
1563
1564<p>Libxml exports an API to handle DTDs and validation, check the <a
1565href="http://xmlsoft.org/html/libxml-valid.html">associated
1566description</a>.</p>
1567
1568<h3><a name="Other1">Other resources</a></h3>
1569
1570<p>DTDs are as old as SGML. So there may be a number of examples on-line, I
1571will just list one for now, others pointers welcome:</p>
1572<ul>
1573 <li><a href="http://www.xml101.com:8081/dtd/">XML-101 DTD</a></li>
1574</ul>
1575
1576<p>I suggest looking at the examples found under test/valid/dtd and any of
1577the large number of books available on XML. The dia example in test/valid
1578should be both simple and complete enough to allow you to build your own.</p>
1579
1580<p></p>
1581
1582<h2><a name="Memory">Memory Management</a></h2>
1583
1584<p>Table of Content:</p>
1585<ol>
1586 <li><a href="#General3">General overview</a></li>
Daniel Veillard9c466822001-10-25 12:03:39 +0000[diff] [blame]1587 <li><a href="#setting">Setting libxml set of memory routines</a></li>
Daniel Veillardb8cfbd12001-10-25 10:53:28 +0000[diff] [blame]1588 <li><a href="#cleanup">Cleaning up after parsing</a></li>
1589 <li><a href="#Debugging">Debugging routines</a></li>
1590 <li><a href="#General4">General memory requirements</a></li>
1591</ol>
1592
1593<h3><a name="General3">General overview</a></h3>
1594
1595<p>The module <code><a
1596href="http://xmlsoft.org/html/libxml-xmlmemory.html">xmlmemory.h</a></code>
1597provides the interfaces to the libxml memory system:</p>
1598<ul>
1599 <li>libxml does not use the libc memory allocator directly but xmlFree(),
1600 xmlMalloc() and xmlRealloc()</li>
1601 <li>those routines can be reallocated to a specific set of routine, by
1602 default the libc ones i.e. free(), malloc() and realloc()</li>
1603 <li>the xmlmemory.c module includes a set of debugging routine</li>
1604</ul>
1605
1606<h3><a name="setting">Setting libxml set of memory routines</a></h3>
1607
1608<p>It is sometimes useful to not use the default memory allocator, either for
1609debugging, analysis or to implement a specific behaviour on memory management
1610(like on embedded systems). Two function calls are available to do so:</p>
1611<ul>
1612 <li><a href="http://xmlsoft.org/html/libxml-xmlmemory.html">xmlMemGet ()</a>
1613 which return the current set of functions in use by the parser</li>
1614 <li><a
1615 href="http://xmlsoft.org/html/libxml-xmlmemory.html">xmlMemSetup()</a>
1616 which allow to set up a new set of memory allocation functions</li>
1617</ul>
1618
1619<p>Of course a call to xmlMemSetup() should probably be done before calling
1620any other libxml routines (unless you are sure your allocations routines are
1621compatibles).</p>
1622
1623<h3><a name="cleanup">Cleaning up after parsing</a></h3>
1624
1625<p>Libxml is not stateless, there is a few set of memory structures needing
1626allocation before the parser is fully functionnal (some encoding structures
1627for example). This also mean that once parsing is finished there is a tiny
1628amount of memory (a few hundred bytes) which can be recollected if you don't
1629reuse the parser immediately:</p>
1630<ul>
1631 <li><a href="http://xmlsoft.org/html/libxml-parser.html">xmlCleanupParser
1632 ()</a>
1633 is a centralized routine to free the parsing states. Note that it won't
1634 deallocate any produced tree if any (use the xmlFreeDoc() and related
1635 routines for this).</li>
1636 <li><a href="http://xmlsoft.org/html/libxml-parser.html">xmlInitParser
1637 ()</a>
1638 is the dual routine allowing to preallocate the parsing state which can
1639 be useful for example to avoid initialization reentrancy problems when
1640 using libxml in multithreaded applications</li>
1641</ul>
1642
1643<p>Generally xmlCleanupParser() is safe, if needed the state will be rebuild
1644at the next invocation of parser routines, but be careful of the consequences
1645in multithreaded applications.</p>
1646
1647<h3><a name="Debugging">Debugging routines</a></h3>
1648
1649<p>When configured using --with-mem-debug flag (off by default), libxml uses
1650a set of memory allocation debugging routineskeeping track of all allocated
1651blocks and the location in the code where the routine was called. A couple of
1652other debugging routines allow to dump the memory allocated infos to a file
1653or call a specific routine when a given block number is allocated:</p>
1654<ul>
1655 <li><a
1656 href="http://xmlsoft.org/html/libxml-xmlmemory.html">xmlMallocLoc()</a>
1657 <a
1658 href="http://xmlsoft.org/html/libxml-xmlmemory.html">xmlReallocLoc()</a>
1659 and <a
1660 href="http://xmlsoft.org/html/libxml-xmlmemory.html">xmlMemStrdupLoc()</a>
1661 are the memory debugging replacement allocation routines</li>
1662 <li><a href="http://xmlsoft.org/html/libxml-xmlmemory.html">xmlMemoryDump
1663 ()</a>
1664 dumps all the informations about the allocated memory block lefts in the
1665 <code>.memdump</code> file</li>
1666</ul>
1667
1668<p>When developping libxml memory debug is enabled, the tests programs call
1669xmlMemoryDump () and the "make test" regression tests will check for any
1670memory leak during the full regression test sequence, this helps a lot
1671ensuring that libxml does not leak memory and bullet proof memory
1672allocations use (some libc implementations are known to be far too permissive
1673resulting in major portability problems!).</p>
1674
1675<p>If the .memdump reports a leak, it displays the allocation function and
1676also tries to give some informations about the content and structure of the
1677allocated blocks left. This is sufficient in most cases to find the culprit,
1678but not always. Assuming the allocation problem is reproductible, it is
1679possible to find more easilly:</p>
1680<ol>
1681 <li>write down the block number xxxx not allocated</li>
1682 <li>export the environement variable XML_MEM_BREAKPOINT=xxxx</li>
1683 <li>run the program under a debugger and set a breakpoint on
1684 xmlMallocBreakpoint() a specific function called when this precise block
1685 is allocated</li>
1686 <li>when the breakpoint is reached you can then do a fine analysis of the
1687 allocation an step to see the condition resulting in the missing
1688 deallocation.</li>
1689</ol>
1690
1691<p>I used to use a commercial tool to debug libxml memory problems but after
1692noticing that it was not detecting memory leaks that simple mechanism was
1693used and proved extremely efficient until now.</p>
1694
1695<h3><a name="General4">General memory requirements</a></h3>
1696
1697<p>How much libxml memory require ? It's hard to tell in average it depends
1698of a number of things:</p>
1699<ul>
1700 <li>the parser itself should work in a fixed amout of memory, except for
1701 information maintained about the stacks of names and entities locations.
1702 The I/O and encoding handlers will probably account for a few KBytes.
1703 This is true for both the XML and HTML parser (though the HTML parser
1704 need more state).</li>
1705 <li>If you are generating the DOM tree then memory requirements will grow
1706 nearly lineary with the size of the data. In general for a balanced
1707 textual document the internal memory requirement is about 4 times the
1708 size of the UTF8 serialization of this document (exmple the XML-1.0
1709 recommendation is a bit more of 150KBytes and takes 650KBytes of main
1710 memory when parsed). Validation will add a amount of memory required for
1711 maintaining the external Dtd state which should be linear with the
1712 complexity of the content model defined by the Dtd</li>
1713 <li>If you don't care about the advanced features of libxml like
1714 validation, DOM, XPath or XPointer, but really need to work fixed memory
1715 requirements, then the SAX interface should be used.</li>
1716</ul>
1717
1718<p></p>
1719
1720<h2><a name="Encodings">Encodings support</a></h2>
1721
1722<p>Table of Content:</p>
1723<ol>
1724 <li><a href="encoding.html#What">What does internationalization support
1725 mean ?</a></li>
1726 <li><a href="encoding.html#internal">The internal encoding, how and
1727 why</a></li>
1728 <li><a href="encoding.html#implemente">How is it implemented ?</a></li>
1729 <li><a href="encoding.html#Default">Default supported encodings</a></li>
1730 <li><a href="encoding.html#extend">How to extend the existing
1731 support</a></li>
1732</ol>
1733
1734<h3><a name="What">What does internationalization support mean ?</a></h3>
1735
1736<p>XML was designed from the start to allow the support of any character set
1737by using Unicode. Any conformant XML parser has to support the UTF-8 and
1738UTF-16 default encodings which can both express the full unicode ranges. UTF8
1739is a variable length encoding whose greatest point are to resuse the same
1740emcoding for ASCII and to save space for Western encodings, but it is a bit
1741more complex to handle in practice. UTF-16 use 2 bytes per characters (and
1742sometimes combines two pairs), it makes implementation easier, but looks a
1743bit overkill for Western languages encoding. Moreover the XML specification
1744allows document to be encoded in other encodings at the condition that they
1745are clearly labelled as such. For example the following is a wellformed XML
1746document encoded in ISO-8859 1 and using accentuated letter that we French
1747likes for both markup and content:</p>
1748<pre>&lt;?xml version="1.0" encoding="ISO-8859-1"?&gt;
1749&lt;très&gt;là&lt;/très&gt;</pre>
1750
1751<p>Having internationalization support in libxml means the foolowing:</p>
1752<ul>
1753 <li>the document is properly parsed</li>
1754 <li>informations about it's encoding are saved</li>
1755 <li>it can be modified</li>
1756 <li>it can be saved in its original encoding</li>
1757 <li>it can also be saved in another encoding supported by libxml (for
1758 example straight UTF8 or even an ASCII form)</li>
1759</ul>
1760
1761<p>Another very important point is that the whole libxml API, with the
1762exception of a few routines to read with a specific encoding or save to a
1763specific encoding, is completely agnostic about the original encoding of the
1764document.</p>
1765
1766<p>It should be noted too that the HTML parser embedded in libxml now obbey
1767the same rules too, the following document will be (as of 2.2.2) handled in
1768an internationalized fashion by libxml too:</p>
1769<pre>&lt;!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN"
1770 "http://www.w3.org/TR/REC-html40/loose.dtd"&gt;
1771&lt;html lang="fr"&gt;
1772&lt;head&gt;
1773 &lt;META HTTP-EQUIV="Content-Type" CONTENT="text/html; charset=ISO-8859-1"&gt;
1774&lt;/head&gt;
1775&lt;body&gt;
1776&lt;p&gt;W3C crée des standards pour le Web.&lt;/body&gt;
1777&lt;/html&gt;</pre>
1778
1779<h3><a name="internal">The internal encoding, how and why</a></h3>
1780
1781<p>One of the core decision was to force all documents to be converted to a
1782default internal encoding, and that encoding to be UTF-8, here are the
1783rationale for those choices:</p>
1784<ul>
1785 <li>keeping the native encoding in the internal form would force the libxml
1786 users (or the code associated) to be fully aware of the encoding of the
1787 original document, for examples when adding a text node to a document,
1788 the content would have to be provided in the document encoding, i.e. the
1789 client code would have to check it before hand, make sure it's conformant
1790 to the encoding, etc ... Very hard in practice, though in some specific
1791 cases this may make sense.</li>
1792 <li>the second decision was which encoding. From the XML spec only UTF8 and
1793 UTF16 really makes sense as being the two only encodings for which there
1794 is amndatory support. UCS-4 (32 bits fixed size encoding) could be
1795 considered an intelligent choice too since it's a direct Unicode mapping
1796 support. I selected UTF-8 on the basis of efficiency and compatibility
1797 with surrounding software:
1798 <ul>
1799 <li>UTF-8 while a bit more complex to convert from/to (i.e. slightly
1800 more costly to import and export CPU wise) is also far more compact
1801 than UTF-16 (and UCS-4) for a majority of the documents I see it used
1802 for right now (RPM RDF catalogs, advogato data, various configuration
1803 file formats, etc.) and the key point for today's computer
1804 architecture is efficient uses of caches. If one nearly double the
1805 memory requirement to store the same amount of data, this will trash
1806 caches (main memory/external caches/internal caches) and my take is
1807 that this harms the system far more than the CPU requirements needed
1808 for the conversion to UTF-8</li>
1809 <li>Most of libxml version 1 users were using it with straight ASCII
1810 most of the time, doing the conversion with an internal encoding
1811 requiring all their code to be rewritten was a serious show-stopper
1812 for using UTF-16 or UCS-4.</li>
1813 <li>UTF-8 is being used as the de-facto internal encoding standard for
1814 related code like the <a href="http://www.pango.org/">pango</a>
1815 upcoming Gnome text widget, and a lot of Unix code (yep another place
1816 where Unix programmer base takes a different approach from Microsoft
1817 - they are using UTF-16)</li>
1818 </ul>
1819 </li>
1820</ul>
1821
1822<p>What does this mean in practice for the libxml user:</p>
1823<ul>
1824 <li>xmlChar, the libxml data type is a byte, those bytes must be assembled
1825 as UTF-8 valid strings. The proper way to terminate an xmlChar * string
1826 is simply to append 0 byte, as usual.</li>
1827 <li>One just need to make sure that when using chars outside the ASCII set,
1828 the values has been properly converted to UTF-8</li>
1829</ul>
1830
1831<h3><a name="implemente">How is it implemented ?</a></h3>
1832
1833<p>Let's describe how all this works within libxml, basically the I18N
1834(internationalization) support get triggered only during I/O operation, i.e.
1835when reading a document or saving one. Let's look first at the reading
1836sequence:</p>
1837<ol>
1838 <li>when a document is processed, we usually don't know the encoding, a
1839 simple heuristic allows to detect UTF-18 and UCS-4 from whose where the
1840 ASCII range (0-0x7F) maps with ASCII</li>
1841 <li>the xml declaration if available is parsed, including the encoding
1842 declaration. At that point, if the autodetected encoding is different
1843 from the one declared a call to xmlSwitchEncoding() is issued.</li>
1844 <li>If there is no encoding declaration, then the input has to be in either
1845 UTF-8 or UTF-16, if it is not then at some point when processing the
1846 input, the converter/checker of UTF-8 form will raise an encoding error.
1847 You may end-up with a garbled document, or no document at all ! Example:
1848 <pre>~/XML -&gt; ./xmllint err.xml
1849err.xml:1: error: Input is not proper UTF-8, indicate encoding !
1850&lt;très&gt;là&lt;/très&gt;
1851 ^
1852err.xml:1: error: Bytes: 0xE8 0x73 0x3E 0x6C
1853&lt;très&gt;là&lt;/très&gt;
1854 ^</pre>
1855 </li>
1856 <li>xmlSwitchEncoding() does an encoding name lookup, canonalize it, and
1857 then search the default registered encoding converters for that encoding.
1858 If it's not within the default set and iconv() support has been compiled
1859 it, it will ask iconv for such an encoder. If this fails then the parser
1860 will report an error and stops processing:
1861 <pre>~/XML -&gt; ./xmllint err2.xml
1862err2.xml:1: error: Unsupported encoding UnsupportedEnc
1863&lt;?xml version="1.0" encoding="UnsupportedEnc"?&gt;
1864 ^</pre>
1865 </li>
1866 <li>From that point the encoder process progressingly the input (it is
1867 plugged as a front-end to the I/O module) for that entity. It captures
1868 and convert on-the-fly the document to be parsed to UTF-8. The parser
1869 itself just does UTF-8 checking of this input and process it
1870 transparently. The only difference is that the encoding information has
1871 been added to the parsing context (more precisely to the input
1872 corresponding to this entity).</li>
1873 <li>The result (when using DOM) is an internal form completely in UTF-8
1874 with just an encoding information on the document node.</li>
1875</ol>
1876
1877<p>Ok then what's happen when saving the document (assuming you
1878colllected/built an xmlDoc DOM like structure) ? It depends on the function
1879called, xmlSaveFile() will just try to save in the original encoding, while
1880xmlSaveFileTo() and xmlSaveFileEnc() can optionally save to a given
1881encoding:</p>
1882<ol>
1883 <li>if no encoding is given, libxml will look for an encoding value
1884 associated to the document and if it exists will try to save to that
1885 encoding,
1886 <p>otherwise everything is written in the internal form, i.e. UTF-8</p>
1887 </li>
1888 <li>so if an encoding was specified, either at the API level or on the
1889 document, libxml will again canonalize the encoding name, lookup for a
1890 converter in the registered set or through iconv. If not found the
1891 function will return an error code</li>
1892 <li>the converter is placed before the I/O buffer layer, as another kind of
1893 buffer, then libxml will simply push the UTF-8 serialization to through
1894 that buffer, which will then progressively be converted and pushed onto
1895 the I/O layer.</li>
1896 <li>It is possible that the converter code fails on some input, for example
1897 trying to push an UTF-8 encoded chinese character through the UTF-8 to
1898 ISO-8859-1 converter won't work. Since the encoders are progressive they
1899 will just report the error and the number of bytes converted, at that
1900 point libxml will decode the offending character, remove it from the
1901 buffer and replace it with the associated charRef encoding &amp;#123; and
1902 resume the convertion. This guarante that any document will be saved
1903 without losses (except for markup names where this is not legal, this is
1904 a problem in the current version, in pactice avoid using non-ascci
1905 characters for tags or attributes names @@). A special "ascii" encoding
1906 name is used to save documents to a pure ascii form can be used when
1907 portability is really crucial</li>
1908</ol>
1909
1910<p>Here is a few examples based on the same test document:</p>
1911<pre>~/XML -&gt; ./xmllint isolat1
1912&lt;?xml version="1.0" encoding="ISO-8859-1"?&gt;
1913&lt;très&gt;là&lt;/très&gt;
1914~/XML -&gt; ./xmllint --encode UTF-8 isolat1
1915&lt;?xml version="1.0" encoding="UTF-8"?&gt;
1916&lt;très&gt;là  &lt;/très&gt;
1917~/XML -&gt; </pre>
1918
1919<p>The same processing is applied (and reuse most of the code) for HTML I18N
1920processing. Looking up and modifying the content encoding is a bit more
1921difficult since it is located in a &lt;meta&gt; tag under the &lt;head&gt;,
1922so a couple of functions htmlGetMetaEncoding() and htmlSetMetaEncoding() have
1923been provided. The parser also attempts to switch encoding on the fly when
1924detecting such a tag on input. Except for that the processing is the same
1925(and again reuses the same code).</p>
1926
1927<h3><a name="Default">Default supported encodings</a></h3>
1928
1929<p>libxml has a set of default converters for the following encodings
1930(located in encoding.c):</p>
1931<ol>
1932 <li>UTF-8 is supported by default (null handlers)</li>
1933 <li>UTF-16, both little and big endian</li>
1934 <li>ISO-Latin-1 (ISO-8859-1) covering most western languages</li>
1935 <li>ASCII, useful mostly for saving</li>
1936 <li>HTML, a specific handler for the conversion of UTF-8 to ASCII with HTML
1937 predefined entities like &amp;copy; for the Copyright sign.</li>
1938</ol>
1939
1940<p>More over when compiled on an Unix platfor with iconv support the full set
1941of encodings supported by iconv can be instantly be used by libxml. On a
1942linux machine with glibc-2.1 the list of supported encodings and aliases fill
19433 full pages, and include UCS-4, the full set of ISO-Latin encodings, and the
1944various Japanese ones.</p>
1945
1946<h4>Encoding aliases</h4>
1947
1948<p>From 2.2.3, libxml has support to register encoding names aliases. The
1949goal is to be able to parse document whose encoding is supported but where
1950the name differs (for example from the default set of names accepted by
1951iconv). The following functions allow to register and handle new aliases for
1952existing encodings. Once registered libxml will automatically lookup the
1953aliases when handling a document:</p>
1954<ul>
1955 <li>int xmlAddEncodingAlias(const char *name, const char *alias);</li>
1956 <li>int xmlDelEncodingAlias(const char *alias);</li>
1957 <li>const char * xmlGetEncodingAlias(const char *alias);</li>
1958 <li>void xmlCleanupEncodingAliases(void);</li>
1959</ul>
1960
1961<h3><a name="extend">How to extend the existing support</a></h3>
1962
1963<p>Well adding support for new encoding, or overriding one of the encoders
1964(assuming it is buggy) should not be hard, just write an input and output
1965conversion routines to/from UTF-8, and register them using
1966xmlNewCharEncodingHandler(name, xxxToUTF8, UTF8Toxxx), and they will be
1967called automatically if the parser(s) encounter such an encoding name
1968(register it uppercase, this will help). The description of the encoders,
1969their arguments and expected return values are described in the encoding.h
1970header.</p>
1971
1972<p>A quick note on the topic of subverting the parser to use a different
1973internal encoding than UTF-8, in some case people will absolutely want to
1974keep the internal encoding different, I think it's still possible (but the
1975encoding must be compliant with ASCII on the same subrange) though I didn't
1976tried it. The key is to override the default conversion routines (by
1977registering null encoders/decoders for your charsets), and bypass the UTF-8
1978checking of the parser by setting the parser context charset
1979(ctxt-&gt;charset) to something different than XML_CHAR_ENCODING_UTF8, but
1980there is no guarantee taht this will work. You may also have some troubles
1981saving back.</p>
1982
1983<p>Basically proper I18N support is important, this requires at least
1984libxml-2.0.0, but a lot of features and corrections are really available only
1985starting 2.2.</p>
1986
1987<h2><a name="IO">I/O Interfaces</a></h2>
1988
1989<p>Table of Content:</p>
1990<ol>
1991 <li><a href="#General1">General overview</a></li>
1992 <li><a href="#basic">The basic buffer type</a></li>
1993 <li><a href="#Input">Input I/O handlers</a></li>
1994 <li><a href="#Output">Output I/O handlers</a></li>
1995 <li><a href="#entities">The entities loader</a></li>
1996 <li><a href="#Example2">Example of customized I/O</a></li>
1997</ol>
1998
1999<h3><a name="General1">General overview</a></h3>
2000
2001<p>The module <code><a
2002href="http://xmlsoft.org/html/libxml-xmlio.html">xmlIO.h</a></code> provides
2003the interfaces to the libxml I/O system. This consists of 4 main parts:</p>
2004<ul>
2005 <li>Entities loader, this is a routine which tries to fetch the entities
2006 (files) based on their PUBLIC and SYSTEM identifiers. The default loader
2007 don't look at the public identifier since libxml do not maintain a
2008 catalog. You can redefine you own entity loader by using
2009 <code>xmlGetExternalEntityLoader()</code> and
Daniel Veillard9c466822001-10-25 12:03:39 +0000[diff] [blame]2010 <code>xmlSetExternalEntityLoader()</code>. <a href="#entities">Check the
2011 example</a>.</li>
Daniel Veillardb8cfbd12001-10-25 10:53:28 +0000[diff] [blame]2012 <li>Input I/O buffers which are a commodity structure used by the parser(s)
2013 input layer to handle fetching the informations to feed the parser. This
2014 provides buffering and is also a placeholder where the encoding
2015 convertors to UTF8 are piggy-backed.</li>
2016 <li>Output I/O buffers are similar to the Input ones and fulfill similar
2017 task but when generating a serialization from a tree.</li>
2018 <li>A mechanism to register sets of I/O callbacks and associate them with
2019 specific naming schemes like the protocol part of the URIs.
2020 <p>This affect the default I/O operations and allows to use specific I/O
2021 handlers for certain names.</p>
2022 </li>
2023</ul>
2024
2025<p>The general mechanism used when loading http://rpmfind.net/xml.html for
2026example in the HTML parser is the following:</p>
2027<ol>
2028 <li>The default entity loader calls <code>xmlNewInputFromFile()</code> with
2029 the parsing context and the URI string.</li>
2030 <li>the URI string is checked against the existing registered handlers
2031 using their match() callback function, if the HTTP module was compiled
2032 in, it is registered and its match() function will succeeds</li>
2033 <li>the open() function of the handler is called and if successful will
2034 return an I/O Input buffer</li>
2035 <li>the parser will the start reading from this buffer and progressively
2036 fetch information from the resource, calling the read() function of the
2037 handler until the resource is exhausted</li>
2038 <li>if an encoding change is detected it will be installed on the input
2039 buffer, providing buffering and efficient use of the conversion
2040 routines</li>
2041 <li>once the parser has finished, the close() function of the handler is
2042 called once and the Input buffer and associed resources are
2043 deallocated.</li>
2044</ol>
2045
2046<p>The user defined callbacks are checked first to allow overriding of the
2047default libxml I/O routines.</p>
2048
2049<h3><a name="basic">The basic buffer type</a></h3>
2050
2051<p>All the buffer manipulation handling is done using the
2052<code>xmlBuffer</code> type define in <code><a
2053href="http://xmlsoft.org/html/libxml-tree.html">tree.h</a> </code>which is a
2054resizable memory buffer. The buffer allocation strategy can be selected to be
2055either best-fit or use an exponential doubling one (CPU vs. memory use
2056tradeoff). The values are <code>XML_BUFFER_ALLOC_EXACT</code> and
2057<code>XML_BUFFER_ALLOC_DOUBLEIT</code>, and can be set individually or on a
2058system wide basis using <code>xmlBufferSetAllocationScheme()</code>. A number
2059of functions allows to manipulate buffers with names starting with the
2060<code>xmlBuffer...</code> prefix.</p>
2061
2062<h3><a name="Input">Input I/O handlers</a></h3>
2063
2064<p>An Input I/O handler is a simple structure
2065<code>xmlParserInputBuffer</code> containing a context associated to the
2066resource (file descriptor, or pointer to a protocol handler), the read() and
2067close() callbacks to use and an xmlBuffer. And extra xmlBuffer and a charset
2068encoding handler are also present to support charset conversion when
2069needed.</p>
2070
2071<h3><a name="Output">Output I/O handlers</a></h3>
2072
2073<p>An Output handler <code>xmlOutputBuffer</code> is completely similar to an
2074Input one except the callbacks are write() and close().</p>
2075
2076<h3><a name="entities">The entities loader</a></h3>
2077
2078<p>The entity loader resolves requests for new entities and create inputs for
2079the parser. Creating an input from a filename or an URI string is done
2080through the xmlNewInputFromFile() routine. The default entity loader do not
2081handle the PUBLIC identifier associated with an entity (if any). So it just
2082calls xmlNewInputFromFile() with the SYSTEM identifier (which is mandatory in
2083XML).</p>
2084
2085<p>If you want to hook up a catalog mechanism then you simply need to
2086override the default entity loader, here is an example:</p>
2087<pre>#include &lt;libxml/xmlIO.h&gt;
2088
2089xmlExternalEntityLoader defaultLoader = NULL;
2090
2091xmlParserInputPtr
2092xmlMyExternalEntityLoader(const char *URL, const char *ID,
2093 xmlParserCtxtPtr ctxt) {
2094 xmlParserInputPtr ret;
2095 const char *fileID = NULL;
2096 /* lookup for the fileID depending on ID */
2097
2098 ret = xmlNewInputFromFile(ctxt, fileID);
2099 if (ret != NULL)
2100 return(ret);
2101 if (defaultLoader != NULL)
2102 ret = defaultLoader(URL, ID, ctxt);
2103 return(ret);
2104}
2105
2106int main(..) {
2107 ...
2108
2109 /*
2110 * Install our own entity loader
2111 */
2112 defaultLoader = xmlGetExternalEntityLoader();
2113 xmlSetExternalEntityLoader(xmlMyExternalEntityLoader);
2114
2115 ...
2116}</pre>
2117
2118<h3><a name="Example2">Example of customized I/O</a></h3>
2119
2120<p>This example come from <a href="http://xmlsoft.org/messages/0708.html">a
2121real use case</a>, xmlDocDump() closes the FILE * passed by the application
2122and this was a problem. The <a
2123href="http://xmlsoft.org/messages/0711.html">solution</a> was to redefine a
2124new output handler with the closing call deactivated:</p>
2125<ol>
2126 <li>First define a new I/O ouput allocator where the output don't close the
2127 file:
2128 <pre>xmlOutputBufferPtr
2129xmlOutputBufferCreateOwn(FILE *file, xmlCharEncodingHandlerPtr encoder) {
2130    xmlOutputBufferPtr ret;
2131    
2132    if (xmlOutputCallbackInitialized == 0)
2133        xmlRegisterDefaultOutputCallbacks();
2134
2135    if (file == NULL) return(NULL);
2136    ret = xmlAllocOutputBuffer(encoder);
2137    if (ret != NULL) {
2138        ret-&gt;context = file;
2139        ret-&gt;writecallback = xmlFileWrite;
2140        ret-&gt;closecallback = NULL; /* No close callback */
2141    }
2142    return(ret); <br>
2143
2144
2145
Daniel Veillard9c466822001-10-25 12:03:39 +0000[diff] [blame]2146
2147
Daniel Veillardc6271d22001-10-27 07:50:58 +0000[diff] [blame]2148
Daniel Veillard51095312001-10-28 18:51:57 +0000[diff] [blame]2149
Daniel Veillard52dcab32001-10-30 12:51:17 +0000[diff] [blame]2150
Daniel Veillarded421aa2001-11-04 21:22:45 +0000[diff] [blame^]2151
Daniel Veillardb8cfbd12001-10-25 10:53:28 +0000[diff] [blame]2152} </pre>
2153 </li>
2154 <li>And then use it to save the document:
2155 <pre>FILE *f;
2156xmlOutputBufferPtr output;
2157xmlDocPtr doc;
2158int res;
2159
2160f = ...
2161doc = ....
2162
2163output = xmlOutputBufferCreateOwn(f, NULL);
2164res = xmlSaveFileTo(output, doc, NULL);
2165 </pre>
2166 </li>
2167</ol>
2168
2169<h2><a name="Catalog">Catalog support</a></h2>
2170
2171<p>Table of Content:</p>
2172<ol>
2173 <li><a href="General2">General overview</a></li>
2174 <li><a href="#definition">The definition</a></li>
2175 <li><a href="#Simple">Using catalogs</a></li>
2176 <li><a href="#Some">Some examples</a></li>
2177 <li><a href="#reference">How to tune catalog usage</a></li>
2178 <li><a href="#validate">How to debug catalog processing</a></li>
2179 <li><a href="#Declaring">How to create and maintain catalogs</a></li>
2180 <li><a href="#implemento">The implementor corner quick review of the
2181 API</a></li>
2182 <li><a href="#Other">Other resources</a></li>
2183</ol>
2184
2185<h3><a name="General2">General overview</a></h3>
2186
2187<p>What is a catalog? Basically it's a lookup mechanism used when an entity
2188(a file or a remote resource) references another entity. The catalog lookup
2189is inserted between the moment the reference is recognized by the software
2190(XML parser, stylesheet processing, or even images referenced for inclusion
2191in a rendering) and the time where loading that resource is actually
2192started.</p>
2193
2194<p>It is basically used for 3 things:</p>
2195<ul>
2196 <li>mapping from "logical" names, the public identifiers and a more
2197 concrete name usable for download (and URI). For example it can associate
2198 the logical name
2199 <p>"-//OASIS//DTD DocBook XML V4.1.2//EN"</p>
2200 <p>of the DocBook 4.1.2 XML DTD with the actual URL where it can be
2201 downloaded</p>
2202 <p>http://www.oasis-open.org/docbook/xml/4.1.2/docbookx.dtd</p>
2203 </li>
2204 <li>remapping from a given URL to another one, like an HTTP indirection
2205 saying that
2206 <p>"http://www.oasis-open.org/committes/tr.xsl"</p>
2207 <p>should really be looked at</p>
2208 <p>"http://www.oasis-open.org/committes/entity/stylesheets/base/tr.xsl"</p>
2209 </li>
2210 <li>providing a local cache mechanism allowing to load the entities
2211 associated to public identifiers or remote resources, this is a really
2212 important feature for any significant deployment of XML or SGML since it
2213 allows to avoid the aleas and delays associated to fetching remote
2214 resources.</li>
2215</ul>
2216
2217<h3><a name="definition">The definitions</a></h3>
2218
2219<p>Libxml, as of 2.4.3 implements 2 kind of catalogs:</p>
2220<ul>
2221 <li>the older SGML catalogs, the official spec is SGML Open Technical
2222 Resolution TR9401:1997, but is better understood by reading <a
2223 href="http://www.jclark.com/sp/catalog.htm">the SP Catalog page</a> from
2224 James Clark. This is relatively old and not the preferred mode of
2225 operation of libxml.</li>
2226 <li><a href="http://www.oasis-open.org/committees/entity/spec.html">XML
2227 Catalogs</a>
2228 is far more flexible, more recent, uses an XML syntax and should scale
2229 quite better. This is the default option of libxml.</li>
2230</ul>
2231
2232<p></p>
2233
2234<h3><a name="Simple">Using catalog</a></h3>
2235
2236<p>In a normal environment libxml will by default check the presence of a
2237catalog in /etc/xml/catalog, and assuming it has been correctly populated,
2238the processing is completely transparent to the document user. To take a
2239concrete example, suppose you are authoring a DocBook document, this one
2240starts with the following DOCTYPE definition:</p>
2241<pre>&lt;?xml version='1.0'?&gt;
2242&lt;!DOCTYPE book PUBLIC "-//Norman Walsh//DTD DocBk XML V3.1.4//EN"
2243 "http://nwalsh.com/docbook/xml/3.1.4/db3xml.dtd"&gt;</pre>
2244
2245<p>When validating the document with libxml, the catalog will be
2246automatically consulted to lookup the public identifier "-//Norman Walsh//DTD
2247DocBk XML V3.1.4//EN" and the system identifier
2248"http://nwalsh.com/docbook/xml/3.1.4/db3xml.dtd", and if these entities have
2249been installed on your system and the catalogs actually point to them, libxml
2250will fetch them from the local disk.</p>
2251
2252<p style="font-size: 10pt"><strong>Note</strong>: Really don't use this
2253DOCTYPE example it's a really old version, but is fine as an example.</p>
2254
2255<p>Libxml will check the catalog each time that it is requested to load an
2256entity, this includes DTD, external parsed entities, stylesheets, etc ... If
2257your system is correctly configured all the authoring phase and processing
2258should use only local files, even if your document stays portable because it
2259uses the canonical public and system ID, referencing the remote document.</p>
2260
2261<h3><a name="Some">Some examples:</a></h3>
2262
2263<p>Here is a couple of fragments from XML Catalogs used in libxml early
2264regression tests in <code>test/catalogs</code> :</p>
2265<pre>&lt;?xml version="1.0"?&gt;
2266&lt;!DOCTYPE catalog PUBLIC
2267 "-//OASIS//DTD Entity Resolution XML Catalog V1.0//EN"
2268 "http://www.oasis-open.org/committees/entity/release/1.0/catalog.dtd"&gt;
2269&lt;catalog xmlns="urn:oasis:names:tc:entity:xmlns:xml:catalog"&gt;
2270 &lt;public publicId="-//OASIS//DTD DocBook XML V4.1.2//EN"
2271 uri="http://www.oasis-open.org/docbook/xml/4.1.2/docbookx.dtd"/&gt;
2272...</pre>
2273
2274<p>This is the beginning of a catalog for DocBook 4.1.2, XML Catalogs are
2275written in XML, there is a specific namespace for catalog elements
2276"urn:oasis:names:tc:entity:xmlns:xml:catalog". The first entry in this
2277catalog is a <code>public</code> mapping it allows to associate a Public
2278Identifier with an URI.</p>
2279<pre>...
2280 &lt;rewriteSystem systemIdStartString="http://www.oasis-open.org/docbook/"
2281 rewritePrefix="file:///usr/share/xml/docbook/"/&gt;
2282...</pre>
2283
2284<p>A <code>rewriteSystem</code> is a very powerful instruction, it says that
2285any URI starting with a given prefix should be looked at another URI
2286constructed by replacing the prefix with an new one. In effect this acts like
2287a cache system for a full area of the Web. In practice it is extremely useful
2288with a file prefix if you have installed a copy of those resources on your
2289local system.</p>
2290<pre>...
2291&lt;delegatePublic publicIdStartString="-//OASIS//DTD XML Catalog //"
2292 catalog="file:///usr/share/xml/docbook.xml"/&gt;
2293&lt;delegatePublic publicIdStartString="-//OASIS//ENTITIES DocBook XML"
2294 catalog="file:///usr/share/xml/docbook.xml"/&gt;
2295&lt;delegatePublic publicIdStartString="-//OASIS//DTD DocBook XML"
2296 catalog="file:///usr/share/xml/docbook.xml"/&gt;
2297&lt;delegateSystem systemIdStartString="http://www.oasis-open.org/docbook/"
2298 catalog="file:///usr/share/xml/docbook.xml"/&gt;
2299&lt;delegateURI uriStartString="http://www.oasis-open.org/docbook/"
2300 catalog="file:///usr/share/xml/docbook.xml"/&gt;
2301...</pre>
2302
2303<p>Delegation is the core features which allows to build a tree of catalogs,
2304easier to maintain than a single catalog, based on Public Identifier, System
2305Identifier or URI prefixes it instructs the catalog software to look up
2306entries in another resource. This feature allow to build hierarchies of
2307catalogs, the set of entries presented should be sufficient to redirect the
2308resolution of all DocBook references to the specific catalog in
2309<code>/usr/share/xml/docbook.xml</code> this one in turn could delegate all
2310references for DocBook 4.2.1 to a specific catalog installed at the same time
2311as the DocBook resources on the local machine.</p>
2312
2313<h3><a name="reference">How to tune catalog usage:</a></h3>
2314
2315<p>The user can change the default catalog behaviour by redirecting queries
2316to its own set of catalogs, this can be done by setting the
2317<code>XML_CATALOG_FILES</code> environment variable to a list of catalogs, an
2318empty one should deactivate loading the default <code>/etc/xml/catalog</code>
2319default catalog</p>
2320
2321<h3><a name="validate">How to debug catalog processing:</a></h3>
2322
2323<p>Setting up the <code>XML_DEBUG_CATALOG</code> environment variable will
2324make libxml output debugging informations for each catalog operations, for
2325example:</p>
2326<pre>orchis:~/XML -&gt; xmllint --memory --noout test/ent2
2327warning: failed to load external entity "title.xml"
2328orchis:~/XML -&gt; export XML_DEBUG_CATALOG=
2329orchis:~/XML -&gt; xmllint --memory --noout test/ent2
2330Failed to parse catalog /etc/xml/catalog
2331Failed to parse catalog /etc/xml/catalog
2332warning: failed to load external entity "title.xml"
2333Catalogs cleanup
2334orchis:~/XML -&gt; </pre>
2335
2336<p>The test/ent2 references an entity, running the parser from memory makes
2337the base URI unavailable and the the "title.xml" entity cannot be loaded.
2338Setting up the debug environment variable allows to detect that an attempt is
2339made to load the <code>/etc/xml/catalog</code> but since it's not present the
2340resolution fails.</p>
2341
2342<p>But the most advanced way to debug XML catalog processing is to use the
2343<strong>xmlcatalog</strong> command shipped with libxml2, it allows to load
2344catalogs and make resolution queries to see what is going on. This is also
2345used for the regression tests:</p>
2346<pre>orchis:~/XML -&gt; ./xmlcatalog test/catalogs/docbook.xml \
2347 "-//OASIS//DTD DocBook XML V4.1.2//EN"
2348http://www.oasis-open.org/docbook/xml/4.1.2/docbookx.dtd
2349orchis:~/XML -&gt; </pre>
2350
2351<p>For debugging what is going on, adding one -v flags increase the verbosity
2352level to indicate the processing done (adding a second flag also indicate
2353what elements are recognized at parsing):</p>
2354<pre>orchis:~/XML -&gt; ./xmlcatalog -v test/catalogs/docbook.xml \
2355 "-//OASIS//DTD DocBook XML V4.1.2//EN"
2356Parsing catalog test/catalogs/docbook.xml's content
2357Found public match -//OASIS//DTD DocBook XML V4.1.2//EN
2358http://www.oasis-open.org/docbook/xml/4.1.2/docbookx.dtd
2359Catalogs cleanup
2360orchis:~/XML -&gt; </pre>
2361
2362<p>A shell interface is also available to debug and process multiple queries
2363(and for regression tests):</p>
2364<pre>orchis:~/XML -&gt; ./xmlcatalog -shell test/catalogs/docbook.xml \
2365 "-//OASIS//DTD DocBook XML V4.1.2//EN"
2366&gt; help
2367Commands available:
2368public PublicID: make a PUBLIC identifier lookup
2369system SystemID: make a SYSTEM identifier lookup
2370resolve PublicID SystemID: do a full resolver lookup
2371add 'type' 'orig' 'replace' : add an entry
2372del 'values' : remove values
2373dump: print the current catalog state
2374debug: increase the verbosity level
2375quiet: decrease the verbosity level
2376exit: quit the shell
2377&gt; public "-//OASIS//DTD DocBook XML V4.1.2//EN"
2378http://www.oasis-open.org/docbook/xml/4.1.2/docbookx.dtd
2379&gt; quit
2380orchis:~/XML -&gt; </pre>
2381
2382<p>This should be sufficient for most debugging purpose, this was actually
2383used heavily to debug the XML Catalog implementation itself.</p>
2384
2385<h3><a name="Declaring">How to create and maintain</a> catalogs:</h3>
2386
2387<p>Basically XML Catalogs are XML files, you can either use XML tools to
2388manage them or use <strong>xmlcatalog</strong> for this. The basic step is
2389to create a catalog the -create option provide this facility:</p>
2390<pre>orchis:~/XML -&gt; ./xmlcatalog --create tst.xml
2391&lt;?xml version="1.0"?&gt;
2392&lt;!DOCTYPE catalog PUBLIC "-//OASIS//DTD Entity Resolution XML Catalog V1.0//EN"
2393 "http://www.oasis-open.org/committees/entity/release/1.0/catalog.dtd"&gt;
2394&lt;catalog xmlns="urn:oasis:names:tc:entity:xmlns:xml:catalog"/&gt;
2395orchis:~/XML -&gt; </pre>
2396
2397<p>By default xmlcatalog does not overwrite the original catalog and save the
2398result on the standard output, this can be overridden using the -noout
2399option. The <code>-add</code> command allows to add entries in the
2400catalog:</p>
2401<pre>orchis:~/XML -&gt; ./xmlcatalog --noout --create --add "public" \
2402 "-//OASIS//DTD DocBook XML V4.1.2//EN" \
2403 http://www.oasis-open.org/docbook/xml/4.1.2/docbookx.dtd tst.xml
2404orchis:~/XML -&gt; cat tst.xml
2405&lt;?xml version="1.0"?&gt;
2406&lt;!DOCTYPE catalog PUBLIC "-//OASIS//DTD Entity Resolution XML Catalog V1.0//EN" \
2407 "http://www.oasis-open.org/committees/entity/release/1.0/catalog.dtd"&gt;
2408&lt;catalog xmlns="urn:oasis:names:tc:entity:xmlns:xml:catalog"&gt;
2409&lt;public publicId="-//OASIS//DTD DocBook XML V4.1.2//EN"
2410 uri="http://www.oasis-open.org/docbook/xml/4.1.2/docbookx.dtd"/&gt;
2411&lt;/catalog&gt;
2412orchis:~/XML -&gt; </pre>
2413
2414<p>The <code>-add</code> option will always take 3 parameters even if some of
2415the XML Catalog constructs (like nextCatalog) will have only a single
2416argument, just pass a third empty string, it will be ignored.</p>
2417
2418<p>Similarly the <code>-del</code> option remove matching entries from the
2419catalog:</p>
2420<pre>orchis:~/XML -&gt; ./xmlcatalog --del \
2421 "http://www.oasis-open.org/docbook/xml/4.1.2/docbookx.dtd" tst.xml
2422&lt;?xml version="1.0"?&gt;
2423&lt;!DOCTYPE catalog PUBLIC "-//OASIS//DTD Entity Resolution XML Catalog V1.0//EN"
2424 "http://www.oasis-open.org/committees/entity/release/1.0/catalog.dtd"&gt;
2425&lt;catalog xmlns="urn:oasis:names:tc:entity:xmlns:xml:catalog"/&gt;
2426orchis:~/XML -&gt; </pre>
2427
2428<p>The catalog is now empty. Note that the matching of <code>-del</code> is
2429exact and would have worked in a similar fashion with the Public ID
2430string.</p>
2431
2432<p>This is rudimentary but should be sufficient to manage a not too complex
2433catalog tree of resources.</p>
2434
2435<h3><a name="implemento">The implementor corner quick review of the
2436API:</a></h3>
2437
2438<p>First, and like for every other module of libxml, there is an
2439automatically generated <a href="html/libxml-catalog.html">API page for
2440catalog support</a>.</p>
2441
2442<p>The header for the catalog interfaces should be included as:</p>
2443<pre>#include &lt;libxml/catalog.h&gt;</pre>
2444
2445<p>The API is voluntarily kept very simple. First it is not obvious that
2446applications really need access to it since it is the default behaviour of
2447libxml (Note: it is possible to completely override libxml default catalog by
2448using <a href="html/libxml-parser.html">xmlSetExternalEntityLoader</a> to
2449plug an application specific resolver).</p>
2450
2451<p>Basically libxml support 2 catalog lists:</p>
2452<ul>
2453 <li>the default one, global shared by all the application</li>
2454 <li>a per-document catalog, this one is built if the document uses the
2455 <code>oasis-xml-catalog</code> PIs to specify its own catalog list, it is
2456 associated to the parser context and destroyed when the parsing context
2457 is destroyed.</li>
2458</ul>
2459
2460<p>the document one will be used first if it exists.</p>
2461
2462<h4>Initialization routines:</h4>
2463
2464<p>xmlInitializeCatalog(), xmlLoadCatalog() and xmlLoadCatalogs() should be
2465used at startup to initialize the catalog, if the catalog should be
2466initialized with specific values xmlLoadCatalog() or xmlLoadCatalogs()
2467should be called before xmlInitializeCatalog() which would otherwise do a
2468default initialization first.</p>
2469
2470<p>The xmlCatalogAddLocal() call is used by the parser to grow the document
2471own catalog list if needed.</p>
2472
2473<h4>Preferences setup:</h4>
2474
2475<p>The XML Catalog spec requires the possibility to select default
2476preferences between public and system delegation,
2477xmlCatalogSetDefaultPrefer() allows this, xmlCatalogSetDefaults() and
2478xmlCatalogGetDefaults() allow to control if XML Catalogs resolution should
2479be forbidden, allowed for global catalog, for document catalog or both, the
2480default is to allow both.</p>
2481
2482<p>And of course xmlCatalogSetDebug() allows to generate debug messages
2483(through the xmlGenericError() mechanism).</p>
2484
2485<h4>Querying routines:</h4>
2486
2487<p>xmlCatalogResolve(), xmlCatalogResolveSystem(), xmlCatalogResolvePublic()
2488and xmlCatalogResolveURI() are relatively explicit if you read the XML
2489Catalog specification they correspond to section 7 algorithms, they should
2490also work if you have loaded an SGML catalog with a simplified semantic.</p>
2491
2492<p>xmlCatalogLocalResolve() and xmlCatalogLocalResolveURI() are the same but
2493operate on the document catalog list</p>
2494
2495<h4>Cleanup and Miscellaneous:</h4>
2496
2497<p>xmlCatalogCleanup() free-up the global catalog, xmlCatalogFreeLocal() is
2498the per-document equivalent.</p>
2499
2500<p>xmlCatalogAdd() and xmlCatalogRemove() are used to dynamically modify the
2501first catalog in the global list, and xmlCatalogDump() allows to dump a
2502catalog state, those routines are primarily designed for xmlcatalog, I'm not
2503sure that exposing more complex interfaces (like navigation ones) would be
2504really useful.</p>
2505
2506<p>The xmlParseCatalogFile() is a function used to load XML Catalog files,
2507it's similar as xmlParseFile() except it bypass all catalog lookups, it's
2508provided because this functionality may be useful for client tools.</p>
2509
2510<h4>threaded environments:</h4>
2511
2512<p>Since the catalog tree is built progressively, some care has been taken to
2513try to avoid troubles in multithreaded environments. The code is now thread
2514safe assuming that the libxml library has been compiled with threads
2515support.</p>
2516
2517<p></p>
2518
2519<h3><a name="Other">Other resources</a></h3>
2520
2521<p>The XML Catalog specification is relatively recent so there isn't much
2522literature to point at:</p>
2523<ul>
2524 <li>You can find an good rant from Norm Walsh about <a
2525 href="http://www.arbortext.com/Think_Tank/XML_Resources/Issue_Three/issue_three.html">the
2526 need for catalogs</a>, it provides a lot of context informations even if
2527 I don't agree with everything presented.</li>
2528 <li>An <a href="http://home.ccil.org/~cowan/XML/XCatalog.html">old XML
2529 catalog proposal</a> from John Cowan</li>
2530 <li>The <a href="http://www.rddl.org/">Resource Directory Description
2531 Language</a> (RDDL) another catalog system but more oriented toward
2532 providing metadata for XML namespaces.</li>
2533 <li>the page from the OASIS Technical <a
2534 href="http://www.oasis-open.org/committees/entity/">Committee on Entity
2535 Resolution</a> who maintains XML Catalog, you will find pointers to the
2536 specification update, some background and pointers to others tools
2537 providing XML Catalog support</li>
2538 <li>I have uploaded <a href="ftp://xmlsoft.org/test/dbk412catalog.tar.gz">a
2539 mall tarball</a> containing XML Catalogs for DocBook 4.1.2 which seems to
2540 work fine for me</li>
2541 <li>The <a href="http://www.xmlsoft.org/xmlcatalog_man.html">xmlcatalog
2542 manual page</a></li>
2543</ul>
2544
2545<p>If you have suggestions for corrections or additions, simply contact
2546me:</p>
2547
2548<h2><a name="library">The parser interfaces</a></h2>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2549
2550<p>This section is directly intended to help programmers getting bootstrapped
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]2551using the XML library from the C language. It is not intended to be
2552extensive. I hope the automatically generated documents will provide the
2553completeness required, but as a separate set of documents. The interfaces of
2554the XML library are by principle low level, there is nearly zero abstraction.
2555Those interested in a higher level API should <a href="#DOM">look at
2556DOM</a>.</p>
Daniel Veillardccb09631998-10-27 06:21:04 +0000[diff] [blame]2557
Daniel Veillard9cb5ff42001-01-29 08:22:21 +0000[diff] [blame]2558<p>The <a href="html/libxml-parser.html">parser interfaces for XML</a> are
2559separated from the <a href="html/libxml-htmlparser.html">HTML parser
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]2560interfaces</a>. Let's have a look at how the XML parser can be called:</p>
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]2561
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]2562<h3><a name="Invoking">Invoking the parser : the pull method</a></h3>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2563
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]2564<p>Usually, the first thing to do is to read an XML input. The parser accepts
2565documents either from in-memory strings or from files. The functions are
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2566defined in "parser.h":</p>
Daniel Veillard10c6a8f1998-10-28 01:00:12 +0000[diff] [blame]2567<dl>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2568 <dt><code>xmlDocPtr xmlParseMemory(char *buffer, int size);</code></dt>
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]2569 <dd><p>Parse a null-terminated string containing the document.</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2570 </dd>
Daniel Veillard10c6a8f1998-10-28 01:00:12 +0000[diff] [blame]2571</dl>
2572<dl>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2573 <dt><code>xmlDocPtr xmlParseFile(const char *filename);</code></dt>
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]2574 <dd><p>Parse an XML document contained in a (possibly compressed)
2575 file.</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2576 </dd>
Daniel Veillard10c6a8f1998-10-28 01:00:12 +0000[diff] [blame]2577</dl>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2578
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]2579<p>The parser returns a pointer to the document structure (or NULL in case of
Daniel Veillard10c6a8f1998-10-28 01:00:12 +0000[diff] [blame]2580failure).</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2581
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]2582<h3 id="Invoking1">Invoking the parser: the push method</h3>
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]2583
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]2584<p>In order for the application to keep the control when the document is
2585being fetched (which is common for GUI based programs) libxml provides a push
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]2586interface, too, as of version 1.8.3. Here are the interface functions:</p>
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]2587<pre>xmlParserCtxtPtr xmlCreatePushParserCtxt(xmlSAXHandlerPtr sax,
2588 void *user_data,
2589 const char *chunk,
2590 int size,
2591 const char *filename);
2592int xmlParseChunk (xmlParserCtxtPtr ctxt,
2593 const char *chunk,
2594 int size,
2595 int terminate);</pre>
2596
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]2597<p>and here is a simple example showing how to use the interface:</p>
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]2598<pre> FILE *f;
2599
2600 f = fopen(filename, "r");
2601 if (f != NULL) {
2602 int res, size = 1024;
2603 char chars[1024];
2604 xmlParserCtxtPtr ctxt;
2605
2606 res = fread(chars, 1, 4, f);
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]2607 if (res &gt; 0) {
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]2608 ctxt = xmlCreatePushParserCtxt(NULL, NULL,
2609 chars, res, filename);
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]2610 while ((res = fread(chars, 1, size, f)) &gt; 0) {
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]2611 xmlParseChunk(ctxt, chars, res, 0);
2612 }
2613 xmlParseChunk(ctxt, chars, 0, 1);
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]2614 doc = ctxt-&gt;myDoc;
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]2615 xmlFreeParserCtxt(ctxt);
2616 }
2617 }</pre>
2618
Daniel Veillardec70e912001-02-26 20:10:45 +0000[diff] [blame]2619<p>The HTML parser embedded into libxml also has a push interface; the
2620functions are just prefixed by "html" rather than "xml".</p>
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]2621
2622<h3 id="Invoking2">Invoking the parser: the SAX interface</h3>
2623
Daniel Veillardec70e912001-02-26 20:10:45 +0000[diff] [blame]2624<p>The tree-building interface makes the parser memory-hungry, first loading
2625the document in memory and then building the tree itself. Reading a document
2626without building the tree is possible using the SAX interfaces (see SAX.h and
2627<a href="http://www.daa.com.au/~james/gnome/xml-sax/xml-sax.html">James
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]2628Henstridge's documentation</a>). Note also that the push interface can be
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]2629limited to SAX: just use the two first arguments of
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]2630<code>xmlCreatePushParserCtxt()</code>.</p>
Daniel Veillardccb09631998-10-27 06:21:04 +0000[diff] [blame]2631
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]2632<h3><a name="Building">Building a tree from scratch</a></h3>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2633
2634<p>The other way to get an XML tree in memory is by building it. Basically
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]2635there is a set of functions dedicated to building new elements. (These are
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]2636also described in &lt;libxml/tree.h&gt;.) For example, here is a piece of
2637code that produces the XML document used in the previous examples:</p>
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]2638<pre> #include &lt;libxml/tree.h&gt;
Daniel Veillard361d8452000-04-03 19:48:13 +0000[diff] [blame]2639 xmlDocPtr doc;
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]2640 xmlNodePtr tree, subtree;
2641
2642 doc = xmlNewDoc("1.0");
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]2643 doc-&gt;children = xmlNewDocNode(doc, NULL, "EXAMPLE", NULL);
2644 xmlSetProp(doc-&gt;children, "prop1", "gnome is great");
2645 xmlSetProp(doc-&gt;children, "prop2", "&amp; linux too");
2646 tree = xmlNewChild(doc-&gt;children, NULL, "head", NULL);
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]2647 subtree = xmlNewChild(tree, NULL, "title", "Welcome to Gnome");
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]2648 tree = xmlNewChild(doc-&gt;children, NULL, "chapter", NULL);
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]2649 subtree = xmlNewChild(tree, NULL, "title", "The Linux adventure");
2650 subtree = xmlNewChild(tree, NULL, "p", "bla bla bla ...");
2651 subtree = xmlNewChild(tree, NULL, "image", NULL);
2652 xmlSetProp(subtree, "href", "linus.gif");</pre>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2653
2654<p>Not really rocket science ...</p>
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]2655
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]2656<h3><a name="Traversing">Traversing the tree</a></h3>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2657
Daniel Veillard9cb5ff42001-01-29 08:22:21 +0000[diff] [blame]2658<p>Basically by <a href="html/libxml-tree.html">including "tree.h"</a> your
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]2659code has access to the internal structure of all the elements of the tree.
2660The names should be somewhat simple like <strong>parent</strong>,
Daniel Veillard306be992000-07-03 12:38:45 +0000[diff] [blame]2661<strong>children</strong>, <strong>next</strong>, <strong>prev</strong>,
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]2662<strong>properties</strong>, etc... For example, still with the previous
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]2663example:</p>
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]2664<pre><code>doc-&gt;children-&gt;children-&gt;children</code></pre>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2665
2666<p>points to the title element,</p>
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]2667<pre>doc-&gt;children-&gt;children-&gt;next-&gt;children-&gt;children</pre>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2668
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]2669<p>points to the text node containing the chapter title "The Linux
2670adventure".</p>
Daniel Veillard10c6a8f1998-10-28 01:00:12 +0000[diff] [blame]2671
Daniel Veillardb24054a1999-12-18 15:32:46 +0000[diff] [blame]2672<p><strong>NOTE</strong>: XML allows <em>PI</em>s and <em>comments</em> to be
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]2673present before the document root, so <code>doc-&gt;children</code> may point
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]2674to an element which is not the document Root Element; a function
Daniel Veillard5cb5ab81999-12-21 15:35:29 +0000[diff] [blame]2675<code>xmlDocGetRootElement()</code> was added for this purpose.</p>
Daniel Veillardb24054a1999-12-18 15:32:46 +0000[diff] [blame]2676
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]2677<h3><a name="Modifying">Modifying the tree</a></h3>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2678
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]2679<p>Functions are provided for reading and writing the document content. Here
Daniel Veillard9cb5ff42001-01-29 08:22:21 +0000[diff] [blame]2680is an excerpt from the <a href="html/libxml-tree.html">tree API</a>:</p>
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]2681<dl>
Daniel Veillarddd6b3671999-09-23 22:19:22 +0000[diff] [blame]2682 <dt><code>xmlAttrPtr xmlSetProp(xmlNodePtr node, const xmlChar *name, const
2683 xmlChar *value);</code></dt>
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]2684 <dd><p>This sets (or changes) an attribute carried by an ELEMENT node.
2685 The value can be NULL.</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2686 </dd>
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]2687</dl>
2688<dl>
Daniel Veillarddd6b3671999-09-23 22:19:22 +0000[diff] [blame]2689 <dt><code>const xmlChar *xmlGetProp(xmlNodePtr node, const xmlChar
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2690 *name);</code></dt>
Daniel Veillardc92c3042000-09-29 02:42:04 +0000[diff] [blame]2691 <dd><p>This function returns a pointer to new copy of the property
2692 content. Note that the user must deallocate the result.</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2693 </dd>
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]2694</dl>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2695
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]2696<p>Two functions are provided for reading and writing the text associated
2697with elements:</p>
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]2698<dl>
Daniel Veillarddd6b3671999-09-23 22:19:22 +0000[diff] [blame]2699 <dt><code>xmlNodePtr xmlStringGetNodeList(xmlDocPtr doc, const xmlChar
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2700 *value);</code></dt>
Daniel Veillardec70e912001-02-26 20:10:45 +0000[diff] [blame]2701 <dd><p>This function takes an "external" string and converts it to one
2702 text node or possibly to a list of entity and text nodes. All
2703 non-predefined entity references like &amp;Gnome; will be stored
2704 internally as entity nodes, hence the result of the function may not be
2705 a single node.</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2706 </dd>
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]2707</dl>
2708<dl>
Daniel Veillarddd6b3671999-09-23 22:19:22 +0000[diff] [blame]2709 <dt><code>xmlChar *xmlNodeListGetString(xmlDocPtr doc, xmlNodePtr list, int
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2710 inLine);</code></dt>
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]2711 <dd><p>This function is the inverse of
2712 <code>xmlStringGetNodeList()</code>. It generates a new string
2713 containing the content of the text and entity nodes. Note the extra
2714 argument inLine. If this argument is set to 1, the function will expand
2715 entity references. For example, instead of returning the &amp;Gnome;
2716 XML encoding in the string, it will substitute it with its value (say,
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]2717 "GNU Network Object Model Environment").</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2718 </dd>
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]2719</dl>
Daniel Veillard10c6a8f1998-10-28 01:00:12 +0000[diff] [blame]2720
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]2721<h3><a name="Saving">Saving a tree</a></h3>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2722
2723<p>Basically 3 options are possible:</p>
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]2724<dl>
Daniel Veillarddd6b3671999-09-23 22:19:22 +0000[diff] [blame]2725 <dt><code>void xmlDocDumpMemory(xmlDocPtr cur, xmlChar**mem, int
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2726 *size);</code></dt>
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]2727 <dd><p>Returns a buffer into which the document has been saved.</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2728 </dd>
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]2729</dl>
2730<dl>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2731 <dt><code>extern void xmlDocDump(FILE *f, xmlDocPtr doc);</code></dt>
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]2732 <dd><p>Dumps a document to an open file descriptor.</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2733 </dd>
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]2734</dl>
2735<dl>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2736 <dt><code>int xmlSaveFile(const char *filename, xmlDocPtr cur);</code></dt>
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]2737 <dd><p>Saves the document to a file. In this case, the compression
2738 interface is triggered if it has been turned on.</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2739 </dd>
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]2740</dl>
Daniel Veillard10c6a8f1998-10-28 01:00:12 +0000[diff] [blame]2741
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]2742<h3><a name="Compressio">Compression</a></h3>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2743
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]2744<p>The library transparently handles compression when doing file-based
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]2745accesses. The level of compression on saves can be turned on either globally
2746or individually for one file:</p>
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]2747<dl>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2748 <dt><code>int xmlGetDocCompressMode (xmlDocPtr doc);</code></dt>
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]2749 <dd><p>Gets the document compression ratio (0-9).</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2750 </dd>
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]2751</dl>
2752<dl>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2753 <dt><code>void xmlSetDocCompressMode (xmlDocPtr doc, int mode);</code></dt>
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]2754 <dd><p>Sets the document compression ratio.</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2755 </dd>
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]2756</dl>
2757<dl>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2758 <dt><code>int xmlGetCompressMode(void);</code></dt>
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]2759 <dd><p>Gets the default compression ratio.</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2760 </dd>
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]2761</dl>
2762<dl>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2763 <dt><code>void xmlSetCompressMode(int mode);</code></dt>
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]2764 <dd><p>Sets the default compression ratio.</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2765 </dd>
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]2766</dl>
2767
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]2768<h2><a name="Entities">Entities or no entities</a></h2>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]2769
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]2770<p>Entities in principle are similar to simple C macros. An entity defines an
2771abbreviation for a given string that you can reuse many times throughout the
2772content of your document. Entities are especially useful when a given string
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]2773may occur frequently within a document, or to confine the change needed to a
2774document to a restricted area in the internal subset of the document (at the
2775beginning). Example:</p>
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]2776<pre>1 &lt;?xml version="1.0"?&gt;
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]27772 &lt;!DOCTYPE EXAMPLE SYSTEM "example.dtd" [
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]27783 &lt;!ENTITY xml "Extensible Markup Language"&gt;
27794 ]&gt;
27805 &lt;EXAMPLE&gt;
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]27816 &amp;xml;
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]27827 &lt;/EXAMPLE&gt;</pre>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]2783
2784<p>Line 3 declares the xml entity. Line 6 uses the xml entity, by prefixing
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]2785its name with '&amp;' and following it by ';' without any spaces added. There
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]2786are 5 predefined entities in libxml allowing you to escape charaters with
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]2787predefined meaning in some parts of the xml document content:
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]2788<strong>&amp;lt;</strong> for the character '&lt;', <strong>&amp;gt;</strong>
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]2789for the character '&gt;', <strong>&amp;apos;</strong> for the character ''',
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]2790<strong>&amp;quot;</strong> for the character '"', and
2791<strong>&amp;amp;</strong> for the character '&amp;'.</p>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]2792
2793<p>One of the problems related to entities is that you may want the parser to
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]2794substitute an entity's content so that you can see the replacement text in
2795your application. Or you may prefer to keep entity references as such in the
2796content to be able to save the document back without losing this usually
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]2797precious information (if the user went through the pain of explicitly
2798defining entities, he may have a a rather negative attitude if you blindly
2799susbtitute them as saving time). The <a
Daniel Veillard9cb5ff42001-01-29 08:22:21 +0000[diff] [blame]2800href="html/libxml-parser.html#XMLSUBSTITUTEENTITIESDEFAULT">xmlSubstituteEntitiesDefault()</a>
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]2801function allows you to check and change the behaviour, which is to not
2802substitute entities by default.</p>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]2803
2804<p>Here is the DOM tree built by libxml for the previous document in the
2805default case:</p>
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]2806<pre>/gnome/src/gnome-xml -&gt; ./xmllint --debug test/ent1
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]2807DOCUMENT
2808version=1.0
2809 ELEMENT EXAMPLE
2810 TEXT
2811 content=
2812 ENTITY_REF
2813 INTERNAL_GENERAL_ENTITY xml
2814 content=Extensible Markup Language
2815 TEXT
2816 content=</pre>
2817
2818<p>And here is the result when substituting entities:</p>
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]2819<pre>/gnome/src/gnome-xml -&gt; ./tester --debug --noent test/ent1
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]2820DOCUMENT
2821version=1.0
2822 ELEMENT EXAMPLE
2823 TEXT
2824 content= Extensible Markup Language</pre>
2825
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]2826<p>So, entities or no entities? Basically, it depends on your use case. I
2827suggest that you keep the non-substituting default behaviour and avoid using
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]2828entities in your XML document or data if you are not willing to handle the
2829entity references elements in the DOM tree.</p>
2830
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]2831<p>Note that at save time libxml enforces the conversion of the predefined
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]2832entities where necessary to prevent well-formedness problems, and will also
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]2833transparently replace those with chars (i.e. it will not generate entity
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]2834reference elements in the DOM tree or call the reference() SAX callback when
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]2835finding them in the input).</p>
2836
Daniel Veillard7b9c4b72000-08-25 16:26:50 +0000[diff] [blame]2837<p><span style="background-color: #FF0000">WARNING</span>: handling entities
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]2838on top of the libxml SAX interface is difficult!!! If you plan to use
Daniel Veillard7b9c4b72000-08-25 16:26:50 +0000[diff] [blame]2839non-predefined entities in your documents, then the learning cuvre to handle
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]2840then using the SAX API may be long. If you plan to use complex documents, I
Daniel Veillard7b9c4b72000-08-25 16:26:50 +0000[diff] [blame]2841strongly suggest you consider using the DOM interface instead and let libxml
Daniel Veillard8c6d6af2000-08-25 17:14:13 +0000[diff] [blame]2842deal with the complexity rather than trying to do it yourself.</p>
Daniel Veillard7b9c4b72000-08-25 16:26:50 +0000[diff] [blame]2843
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]2844<h2><a name="Namespaces">Namespaces</a></h2>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]2845
Daniel Veillardec303412000-03-24 13:41:54 +0000[diff] [blame]2846<p>The libxml library implements <a
2847href="http://www.w3.org/TR/REC-xml-names/">XML namespaces</a> support by
2848recognizing namespace contructs in the input, and does namespace lookup
2849automatically when building the DOM tree. A namespace declaration is
2850associated with an in-memory structure and all elements or attributes within
2851that namespace point to it. Hence testing the namespace is a simple and fast
2852equality operation at the user level.</p>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]2853
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]2854<p>I suggest that people using libxml use a namespace, and declare it in the
2855root element of their document as the default namespace. Then they don't need
2856to use the prefix in the content but we will have a basis for future semantic
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]2857refinement and merging of data from different sources. This doesn't increase
Daniel Veillardec70e912001-02-26 20:10:45 +0000[diff] [blame]2858the size of the XML output significantly, but significantly increases its
2859value in the long-term. Example:</p>
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]2860<pre>&lt;mydoc xmlns="http://mydoc.example.org/schemas/"&gt;
2861 &lt;elem1&gt;...&lt;/elem1&gt;
2862 &lt;elem2&gt;...&lt;/elem2&gt;
2863&lt;/mydoc&gt;</pre>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]2864
Daniel Veillardec70e912001-02-26 20:10:45 +0000[diff] [blame]2865<p>The namespace value has to be an absolute URL, but the URL doesn't have to
2866point to any existing resource on the Web. It will bind all the element and
2867atributes with that URL. I suggest to use an URL within a domain you control,
2868and that the URL should contain some kind of version information if possible.
2869For example, <code>"http://www.gnome.org/gnumeric/1.0/"</code> is a good
2870namespace scheme.</p>
Daniel Veillardec303412000-03-24 13:41:54 +0000[diff] [blame]2871
2872<p>Then when you load a file, make sure that a namespace carrying the
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]2873version-independent prefix is installed on the root element of your document,
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]2874and if the version information don't match something you know, warn the user
2875and be liberal in what you accept as the input. Also do *not* try to base
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]2876namespace checking on the prefix value. &lt;foo:text&gt; may be exactly the
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]2877same as &lt;bar:text&gt; in another document. What really matters is the URI
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]2878associated with the element or the attribute, not the prefix string (which is
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]2879just a shortcut for the full URI). In libxml, element and attributes have an
Daniel Veillardec303412000-03-24 13:41:54 +0000[diff] [blame]2880<code>ns</code> field pointing to an xmlNs structure detailing the namespace
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]2881prefix and its URI.</p>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]2882
2883<p>@@Interfaces@@</p>
2884
2885<p>@@Examples@@</p>
2886
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]2887<p>Usually people object to using namespaces together with validity checking.
2888I will try to make sure that using namespaces won't break validity checking,
2889so even if you plan to use or currently are using validation I strongly
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]2890suggest adding namespaces to your document. A default namespace scheme
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]2891<code>xmlns="http://...."</code> should not break validity even on less
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]2892flexible parsers. Using namespaces to mix and differentiate content coming
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]2893from multiple DTDs will certainly break current validation schemes. I will
2894try to provide ways to do this, but this may not be portable or
2895standardized.</p>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]2896
Daniel Veillardb8cfbd12001-10-25 10:53:28 +0000[diff] [blame]2897<h2><a name="Upgrading">Upgrading 1.x code</a></h2>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]2898
Daniel Veillardb8cfbd12001-10-25 10:53:28 +0000[diff] [blame]2899<p>Incompatible changes:</p>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]2900
Daniel Veillardb8cfbd12001-10-25 10:53:28 +0000[diff] [blame]2901<p>Version 2 of libxml is the first version introducing serious backward
2902incompatible changes. The main goals were:</p>
2903<ul>
2904 <li>a general cleanup. A number of mistakes inherited from the very early
2905 versions couldn't be changed due to compatibility constraints. Example
2906 the "childs" element in the nodes.</li>
2907 <li>Uniformization of the various nodes, at least for their header and link
2908 parts (doc, parent, children, prev, next), the goal is a simpler
2909 programming model and simplifying the task of the DOM implementors.</li>
2910 <li>better conformances to the XML specification, for example version 1.x
2911 had an heuristic to try to detect ignorable white spaces. As a result the
2912 SAX event generated were ignorableWhitespace() while the spec requires
2913 character() in that case. This also mean that a number of DOM node
2914 containing blank text may populate the DOM tree which were not present
2915 before.</li>
2916</ul>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]2917
Daniel Veillardb8cfbd12001-10-25 10:53:28 +0000[diff] [blame]2918<h3>How to fix libxml-1.x code:</h3>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]2919
Daniel Veillardb8cfbd12001-10-25 10:53:28 +0000[diff] [blame]2920<p>So client code of libxml designed to run with version 1.x may have to be
2921changed to compile against version 2.x of libxml. Here is a list of changes
2922that I have collected, they may not be sufficient, so in case you find other
2923change which are required, <a href="mailto:Daniel.Ïeillardw3.org">drop me a
2924mail</a>:</p>
2925<ol>
2926 <li>The package name have changed from libxml to libxml2, the library name
2927 is now -lxml2 . There is a new xml2-config script which should be used to
2928 select the right parameters libxml2</li>
2929 <li>Node <strong>childs</strong> field has been renamed
2930 <strong>children</strong> so s/childs/children/g should be applied
2931 (probablility of having "childs" anywere else is close to 0+</li>
2932 <li>The document don't have anymore a <strong>root</strong> element it has
2933 been replaced by <strong>children</strong> and usually you will get a
2934 list of element here. For example a Dtd element for the internal subset
2935 and it's declaration may be found in that list, as well as processing
2936 instructions or comments found before or after the document root element.
2937 Use <strong>xmlDocGetRootElement(doc)</strong> to get the root element of
2938 a document. Alternatively if you are sure to not reference Dtds nor have
2939 PIs or comments before or after the root element
2940 s/-&gt;root/-&gt;children/g will probably do it.</li>
2941 <li>The white space issue, this one is more complex, unless special case of
2942 validating parsing, the line breaks and spaces usually used for indenting
2943 and formatting the document content becomes significant. So they are
2944 reported by SAX and if your using the DOM tree, corresponding nodes are
2945 generated. Too approach can be taken:
2946 <ol>
2947 <li>lazy one, use the compatibility call
2948 <strong>xmlKeepBlanksDefault(0)</strong> but be aware that you are
2949 relying on a special (and possibly broken) set of heuristics of
2950 libxml to detect ignorable blanks. Don't complain if it breaks or
2951 make your application not 100% clean w.r.t. to it's input.</li>
2952 <li>the Right Way: change you code to accept possibly unsignificant
2953 blanks characters, or have your tree populated with weird blank text
2954 nodes. You can spot them using the comodity function
2955 <strong>xmlIsBlankNode(node)</strong> returning 1 for such blank
2956 nodes.</li>
2957 </ol>
2958 <p>Note also that with the new default the output functions don't add any
2959 extra indentation when saving a tree in order to be able to round trip
2960 (read and save) without inflating the document with extra formatting
2961 chars.</p>
2962 </li>
2963 <li>The include path has changed to $prefix/libxml/ and the includes
2964 themselves uses this new prefix in includes instructions... If you are
2965 using (as expected) the
2966 <pre>xml2-config --cflags</pre>
2967 <p>output to generate you compile commands this will probably work out of
2968 the box</p>
2969 </li>
2970 <li>xmlDetectCharEncoding takes an extra argument indicating the lenght in
2971 byte of the head of the document available for character detection.</li>
2972</ol>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]2973
Daniel Veillardb8cfbd12001-10-25 10:53:28 +0000[diff] [blame]2974<h3>Ensuring both libxml-1.x and libxml-2.x compatibility</h3>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]2975
Daniel Veillardb8cfbd12001-10-25 10:53:28 +0000[diff] [blame]2976<p>Two new version of libxml (1.8.11) and libxml2 (2.3.4) have been released
2977to allow smoth upgrade of existing libxml v1code while retaining
2978compatibility. They offers the following:</p>
2979<ol>
2980 <li>similar include naming, one should use
2981 <strong>#include&lt;libxml/...&gt;</strong> in both cases.</li>
2982 <li>similar identifiers defined via macros for the child and root fields:
2983 respectively <strong>xmlChildrenNode</strong> and
2984 <strong>xmlRootNode</strong></li>
2985 <li>a new macro <strong>LIBXML_TEST_VERSION</strong> which should be
2986 inserted once in the client code</li>
2987</ol>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]2988
Daniel Veillardb8cfbd12001-10-25 10:53:28 +0000[diff] [blame]2989<p>So the roadmap to upgrade your existing libxml applications is the
2990following:</p>
2991<ol>
2992 <li>install the libxml-1.8.8 (and libxml-devel-1.8.8) packages</li>
2993 <li>find all occurences where the xmlDoc <strong>root</strong> field is
2994 used and change it to <strong>xmlRootNode</strong></li>
2995 <li>similary find all occurences where the xmlNode <strong>childs</strong>
2996 field is used and change it to <strong>xmlChildrenNode</strong></li>
2997 <li>add a <strong>LIBXML_TEST_VERSION</strong> macro somewhere in your
2998 <strong>main()</strong> or in the library init entry point</li>
2999 <li>Recompile, check compatibility, it should still work</li>
3000 <li>Change your configure script to look first for xml2-config and fallback
3001 using xml-config . Use the --cflags and --libs ouptut of the command as
3002 the Include and Linking parameters needed to use libxml.</li>
3003 <li>install libxml2-2.3.x and libxml2-devel-2.3.x (libxml-1.8.y and
3004 libxml-devel-1.8.y can be kept simultaneously)</li>
3005 <li>remove your config.cache, relaunch your configuration mechanism, and
3006 recompile, if steps 2 and 3 were done right it should compile as-is</li>
3007 <li>Test that your application is still running correctly, if not this may
3008 be due to extra empty nodes due to formating spaces being kept in libxml2
3009 contrary to libxml1, in that case insert xmlKeepBlanksDefault(1) in your
3010 code before calling the parser (next to
3011 <strong>LIBXML_TEST_VERSION</strong> is a fine place).</li>
3012</ol>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]3013
Daniel Veillardb8cfbd12001-10-25 10:53:28 +0000[diff] [blame]3014<p>Following those steps should work. It worked for some of my own code.</p>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]3015
Daniel Veillardb8cfbd12001-10-25 10:53:28 +0000[diff] [blame]3016<p>Let me put some emphasis on the fact that there is far more changes from
3017libxml 1.x to 2.x than the ones you may have to patch for. The overall code
3018has been considerably cleaned up and the conformance to the XML specification
3019has been drastically improved too. Don't take those changes as an excuse to
3020not upgrade, it may cost a lot on the long term ...</p>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]3021
Daniel Veillard52dcab32001-10-30 12:51:17 +0000[diff] [blame]3022<h2><a name="Thread">Thread safety</a></h2>
3023
3024<p>Starting with 2.4.7, libxml makes provisions to ensure that concurent
3025threads can safely work in parallel parsing different documents. There is
3026however a couple of things to do to ensure it:</p>
3027<ul>
3028 <li>configure the library accordingly using the --with-threads options</li>
3029 <li>call xmlInitParser() in the "main" thread before using any of the
3030 libxml API (except possibly selecting a different memory allocator)</li>
3031</ul>
3032
3033<p>Note that the thread safety cannot be ensured for multiple threads sharing
3034the same document, the locking must be done at the application level, libxml
3035exports a basic mutex and reentrant mutexes API in &lt;libxml/threads.h&gt;.
3036The parts of the library checked for thread safety are:</p>
3037<ul>
3038 <li>concurrent loading</li>
3039 <li>file access resolution</li>
3040 <li>catalog access</li>
3041 <li>catalog building</li>
3042 <li>entities lookup/accesses</li>
3043 <li>validation</li>
3044 <li>global variables per-thread override</li>
3045 <li>memory handling</li>
3046</ul>
3047
3048<p>XPath is supposed to be thread safe now, but this wasn't tested
3049seriously.</p>
3050
Daniel Veillard35008381999-10-25 13:15:52 +0000[diff] [blame]3051<h2><a name="DOM"></a><a name="Principles">DOM Principles</a></h2>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]3052
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]3053<p><a href="http://www.w3.org/DOM/">DOM</a> stands for the <em>Document
3054Object Model</em>; this is an API for accessing XML or HTML structured
3055documents. Native support for DOM in Gnome is on the way (module gnome-dom),
3056and will be based on gnome-xml. This will be a far cleaner interface to
3057manipulate XML files within Gnome since it won't expose the internal
3058structure.</p>
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]3059
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]3060<p>The current DOM implementation on top of libxml is the <a
Daniel Veillarda47fb3d2001-03-25 17:23:49 +0000[diff] [blame]3061href="http://cvs.gnome.org/lxr/source/gdome2/">gdome2 Gnome module</a>, this
3062is a full DOM interface, thanks to Paolo Casarini, check the <a
3063href="http://www.cs.unibo.it/~casarini/gdome2/">Gdome2 homepage</a> for more
3064informations.</p>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]3065
Daniel Veillard35008381999-10-25 13:15:52 +0000[diff] [blame]3066<h2><a name="Example"></a><a name="real">A real example</a></h2>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]3067
3068<p>Here is a real size example, where the actual content of the application
3069data is not kept in the DOM tree but uses internal structures. It is based on
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]3070a proposal to keep a database of jobs related to Gnome, with an XML based
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]3071storage structure. Here is an <a href="gjobs.xml">XML encoded jobs
3072base</a>:</p>
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]3073<pre>&lt;?xml version="1.0"?&gt;
3074&lt;gjob:Helping xmlns:gjob="http://www.gnome.org/some-location"&gt;
3075 &lt;gjob:Jobs&gt;
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]3076
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]3077 &lt;gjob:Job&gt;
3078 &lt;gjob:Project ID="3"/&gt;
3079 &lt;gjob:Application&gt;GBackup&lt;/gjob:Application&gt;
3080 &lt;gjob:Category&gt;Development&lt;/gjob:Category&gt;
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]3081
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]3082 &lt;gjob:Update&gt;
3083 &lt;gjob:Status&gt;Open&lt;/gjob:Status&gt;
3084 &lt;gjob:Modified&gt;Mon, 07 Jun 1999 20:27:45 -0400 MET DST&lt;/gjob:Modified&gt;
3085 &lt;gjob:Salary&gt;USD 0.00&lt;/gjob:Salary&gt;
3086 &lt;/gjob:Update&gt;
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]3087
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]3088 &lt;gjob:Developers&gt;
3089 &lt;gjob:Developer&gt;
3090 &lt;/gjob:Developer&gt;
3091 &lt;/gjob:Developers&gt;
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]3092
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]3093 &lt;gjob:Contact&gt;
3094 &lt;gjob:Person&gt;Nathan Clemons&lt;/gjob:Person&gt;
3095 &lt;gjob:Email&gt;nathan@windsofstorm.net&lt;/gjob:Email&gt;
3096 &lt;gjob:Company&gt;
3097 &lt;/gjob:Company&gt;
3098 &lt;gjob:Organisation&gt;
3099 &lt;/gjob:Organisation&gt;
3100 &lt;gjob:Webpage&gt;
3101 &lt;/gjob:Webpage&gt;
3102 &lt;gjob:Snailmail&gt;
3103 &lt;/gjob:Snailmail&gt;
3104 &lt;gjob:Phone&gt;
3105 &lt;/gjob:Phone&gt;
3106 &lt;/gjob:Contact&gt;
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]3107
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]3108 &lt;gjob:Requirements&gt;
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]3109 The program should be released as free software, under the GPL.
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]3110 &lt;/gjob:Requirements&gt;
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]3111
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]3112 &lt;gjob:Skills&gt;
3113 &lt;/gjob:Skills&gt;
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]3114
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]3115 &lt;gjob:Details&gt;
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]3116 A GNOME based system that will allow a superuser to configure
3117 compressed and uncompressed files and/or file systems to be backed
3118 up with a supported media in the system. This should be able to
3119 perform via find commands generating a list of files that are passed
3120 to tar, dd, cpio, cp, gzip, etc., to be directed to the tape machine
3121 or via operations performed on the filesystem itself. Email
3122 notification and GUI status display very important.
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]3123 &lt;/gjob:Details&gt;
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]3124
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]3125 &lt;/gjob:Job&gt;
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]3126
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]3127 &lt;/gjob:Jobs&gt;
3128&lt;/gjob:Helping&gt;</pre>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]3129
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]3130<p>While loading the XML file into an internal DOM tree is a matter of
3131calling only a couple of functions, browsing the tree to gather the ata and
3132generate the internal structures is harder, and more error prone.</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]3133
3134<p>The suggested principle is to be tolerant with respect to the input
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]3135structure. For example, the ordering of the attributes is not significant,
3136the XML specification is clear about it. It's also usually a good idea not to
Daniel Veillardec70e912001-02-26 20:10:45 +0000[diff] [blame]3137depend on the order of the children of a given node, unless it really makes
3138things harder. Here is some code to parse the information for a person:</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]3139<pre>/*
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]3140 * A person record
3141 */
3142typedef struct person {
3143 char *name;
3144 char *email;
3145 char *company;
3146 char *organisation;
3147 char *smail;
3148 char *webPage;
3149 char *phone;
3150} person, *personPtr;
3151
3152/*
3153 * And the code needed to parse it
3154 */
3155personPtr parsePerson(xmlDocPtr doc, xmlNsPtr ns, xmlNodePtr cur) {
3156 personPtr ret = NULL;
3157
3158DEBUG("parsePerson\n");
3159 /*
3160 * allocate the struct
3161 */
3162 ret = (personPtr) malloc(sizeof(person));
3163 if (ret == NULL) {
3164 fprintf(stderr,"out of memory\n");
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]3165 return(NULL);
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]3166 }
3167 memset(ret, 0, sizeof(person));
3168
3169 /* We don't care what the top level element name is */
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]3170 cur = cur-&gt;xmlChildrenNode;
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]3171 while (cur != NULL) {
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]3172 if ((!strcmp(cur-&gt;name, "Person")) &amp;&amp; (cur-&gt;ns == ns))
3173 ret-&gt;name = xmlNodeListGetString(doc, cur-&gt;xmlChildrenNode, 1);
3174 if ((!strcmp(cur-&gt;name, "Email")) &amp;&amp; (cur-&gt;ns == ns))
3175 ret-&gt;email = xmlNodeListGetString(doc, cur-&gt;xmlChildrenNode, 1);
3176 cur = cur-&gt;next;
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]3177 }
3178
3179 return(ret);
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]3180}</pre>
3181
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]3182<p>Here are a couple of things to notice:</p>
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]3183<ul>
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]3184 <li>Usually a recursive parsing style is the more convenient one: XML data
3185 is by nature subject to repetitive constructs and usually exibits highly
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]3186 stuctured patterns.</li>
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]3187 <li>The two arguments of type <em>xmlDocPtr</em> and <em>xmlNsPtr</em>,
3188 i.e. the pointer to the global XML document and the namespace reserved to
3189 the application. Document wide information are needed for example to
3190 decode entities and it's a good coding practice to define a namespace for
3191 your application set of data and test that the element and attributes
3192 you're analyzing actually pertains to your application space. This is
3193 done by a simple equality test (cur-&gt;ns == ns).</li>
Daniel Veillardec70e912001-02-26 20:10:45 +0000[diff] [blame]3194 <li>To retrieve text and attributes value, you can use the function
3195 <em>xmlNodeListGetString</em> to gather all the text and entity reference
3196 nodes generated by the DOM output and produce an single text string.</li>
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]3197</ul>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]3198
3199<p>Here is another piece of code used to parse another level of the
3200structure:</p>
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]3201<pre>#include &lt;libxml/tree.h&gt;
Daniel Veillard361d8452000-04-03 19:48:13 +0000[diff] [blame]3202/*
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]3203 * a Description for a Job
3204 */
3205typedef struct job {
3206 char *projectID;
3207 char *application;
3208 char *category;
3209 personPtr contact;
3210 int nbDevelopers;
3211 personPtr developers[100]; /* using dynamic alloc is left as an exercise */
3212} job, *jobPtr;
3213
3214/*
3215 * And the code needed to parse it
3216 */
3217jobPtr parseJob(xmlDocPtr doc, xmlNsPtr ns, xmlNodePtr cur) {
3218 jobPtr ret = NULL;
3219
3220DEBUG("parseJob\n");
3221 /*
3222 * allocate the struct
3223 */
3224 ret = (jobPtr) malloc(sizeof(job));
3225 if (ret == NULL) {
3226 fprintf(stderr,"out of memory\n");
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]3227 return(NULL);
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]3228 }
3229 memset(ret, 0, sizeof(job));
3230
3231 /* We don't care what the top level element name is */
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]3232 cur = cur-&gt;xmlChildrenNode;
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]3233 while (cur != NULL) {
3234
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]3235 if ((!strcmp(cur-&gt;name, "Project")) &amp;&amp; (cur-&gt;ns == ns)) {
3236 ret-&gt;projectID = xmlGetProp(cur, "ID");
3237 if (ret-&gt;projectID == NULL) {
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]3238 fprintf(stderr, "Project has no ID\n");
3239 }
3240 }
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]3241 if ((!strcmp(cur-&gt;name, "Application")) &amp;&amp; (cur-&gt;ns == ns))
3242 ret-&gt;application = xmlNodeListGetString(doc, cur-&gt;xmlChildrenNode, 1);
3243 if ((!strcmp(cur-&gt;name, "Category")) &amp;&amp; (cur-&gt;ns == ns))
3244 ret-&gt;category = xmlNodeListGetString(doc, cur-&gt;xmlChildrenNode, 1);
3245 if ((!strcmp(cur-&gt;name, "Contact")) &amp;&amp; (cur-&gt;ns == ns))
3246 ret-&gt;contact = parsePerson(doc, ns, cur);
3247 cur = cur-&gt;next;
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]3248 }
3249
3250 return(ret);
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]3251}</pre>
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]3252
Daniel Veillardec70e912001-02-26 20:10:45 +0000[diff] [blame]3253<p>Once you are used to it, writing this kind of code is quite simple, but
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]3254boring. Ultimately, it could be possble to write stubbers taking either C
3255data structure definitions, a set of XML examples or an XML DTD and produce
3256the code needed to import and export the content between C data and XML
3257storage. This is left as an exercise to the reader :-)</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]3258
Daniel Veillard6f0adb52000-07-03 11:41:26 +0000[diff] [blame]3259<p>Feel free to use <a href="example/gjobread.c">the code for the full C
3260parsing example</a> as a template, it is also available with Makefile in the
3261Gnome CVS base under gnome-xml/example</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]3262
Daniel Veillardc310d562000-06-23 18:32:15 +0000[diff] [blame]3263<h2><a name="Contributi">Contributions</a></h2>
3264<ul>
Daniel Veillardb8cfbd12001-10-25 10:53:28 +0000[diff] [blame]3265 <li>Bjorn Reese, William Brack and Thomas Broyer have provided a number of
3266 patches, Gary Pennington worked on the validation API, threading support
3267 and Solaris port.</li>
3268 <li>John Fleck helps maintaining the documentation and man pages.</li>
Daniel Veillardc6271d22001-10-27 07:50:58 +0000[diff] [blame]3269 <li><a href="mailto:ari@lusis.org">Ari Johnson</a>
Daniel Veillard51095312001-10-28 18:51:57 +0000[diff] [blame]3270 provides a C++ wrapper for libxml:<br>
Daniel Veillardc6271d22001-10-27 07:50:58 +0000[diff] [blame]3271 Website: <a
3272 href="http://lusis.org/~ari/xml++/">http://lusis.org/~ari/xml++/</a><br>
3273 Download: <a
Daniel Veillard51095312001-10-28 18:51:57 +0000[diff] [blame]3274 href="http://lusis.org/~ari/xml++/libxml++.tar.gz">http://lusis.org/~ari/xml++/libxml++.tar.gz</a></li>
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]3275 <li><a href="mailto:izlatkovic@daenet.de">Igor Zlatkovic</a>
3276 is now the maintainer of the Windows port, <a
Daniel Veillard95189532001-07-26 18:30:26 +0000[diff] [blame]3277 href="http://www.fh-frankfurt.de/~igor/projects/libxml/index.html">he
3278 provides binaries</a></li>
Daniel Veillardc9484202001-10-24 12:35:52 +0000[diff] [blame]3279 <li><a href="mailto:Gary.Pennington@sun.com">Gary Pennington</a>
3280 provides <a href="http://pages.eidosnet.co.uk/~garypen/libxml/">Solaris
Daniel Veillard0a702dc2001-10-19 14:50:57 +0000[diff] [blame]3281 binaries</a></li>
Daniel Veillarde356c282001-03-10 12:32:04 +0000[diff] [blame]3282 <li><a
3283 href="http://mail.gnome.org/archives/xml/2001-March/msg00014.html">Matt
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]3284 Sergeant</a>
3285 developped <a href="http://axkit.org/download/">XML::LibXSLT</a>, a perl
3286 wrapper for libxml2/libxslt as part of the <a
3287 href="http://axkit.com/">AxKit XML application server</a></li>
3288 <li><a href="mailto:fnatter@gmx.net">Felix Natter</a>
3289 and <a href="mailto:geertk@ai.rug.nl">Geert Kloosterman</a> provide <a
Daniel Veillardca989762001-06-23 17:39:29 +0000[diff] [blame]3290 href="libxml-doc.el">an emacs module</a> to lookup libxml(2) functions
Daniel Veillard3f6f7f62000-06-30 17:58:25 +0000[diff] [blame]3291 documentation</li>
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]3292 <li><a href="mailto:sherwin@nlm.nih.gov">Ziying Sherwin</a>
3293 provided <a href="http://xmlsoft.org/messages/0488.html">man
3294 pages</a></li>
Daniel Veillard5168dbf2001-07-07 00:18:23 +0000[diff] [blame]3295 <li>there is a module for <a
3296 href="http://acs-misc.sourceforge.net/nsxml.html">libxml/libxslt support
3297 in OpenNSD/AOLServer</a></li>
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]3298 <li><a href="mailto:dkuhlman@cutter.rexx.com">Dave Kuhlman</a>
3299 provides libxml/libxslt <a href="http://www.rexx.com/~dkuhlman">wrappers
3300 for Python</a></li>
Daniel Veillardc310d562000-06-23 18:32:15 +0000[diff] [blame]3301</ul>
3302
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]3303<p></p>
Daniel Veillardccb09631998-10-27 06:21:04 +0000[diff] [blame]3304</body>
3305</html>