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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 Veillardc9484202001-10-24 12:35:52 +0000[diff] [blame]13<h1 style="text-align: center">libxml, a.k.a. gnome-xml</h1>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]14
15<p></p>
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]16<ul>
17 <li><a href="#Introducti">Introduction</a></li>
18 <li><a href="#Documentat">Documentation</a></li>
Daniel Veillardd5f97f82000-09-17 16:38:14 +0000[diff] [blame]19 <li><a href="#Reporting">Reporting bugs and getting help</a></li>
20 <li><a href="#help">how to help</a></li>
Daniel Veillard10a2c651999-12-12 13:03:50 +0000[diff] [blame]21 <li><a href="#Downloads">Downloads</a></li>
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]22 <li><a href="#News">News</a></li>
23 <li><a href="#XML">XML</a></li>
Daniel Veillard82687162001-01-22 15:32:01 +0000[diff] [blame]24 <li><a href="#XSLT">XSLT</a></li>
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]25 <li><a href="#tree">The tree output</a></li>
26 <li><a href="#interface">The SAX interface</a></li>
Daniel Veillardc9484202001-10-24 12:35:52 +0000[diff] [blame]27 <li><a href="#library">The XML library interfaces</a></li>
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]28 <li><a href="#Entities">Entities or no entities</a></li>
29 <li><a href="#Namespaces">Namespaces</a></li>
30 <li><a href="#Validation">Validation</a></li>
31 <li><a href="#Principles">DOM principles</a></li>
32 <li><a href="#real">A real example</a></li>
Daniel Veillard96984452000-08-31 13:50:12 +0000[diff] [blame]33 <li><a href="#Contributi">Contributions</a></li>
34</ul>
35
36<p>Separate documents:</p>
37<ul>
Daniel Veillard6e6a6cc2001-02-15 15:55:44 +0000[diff] [blame]38 <li><a href="http://xmlsoft.org/XSLT/">the libxslt page</a></li>
Daniel Veillard7b06bcb2001-06-22 16:03:51 +0000[diff] [blame]39 <li><a href="http://www.cs.unibo.it/~casarini/gdome2/">the gdome2 page: a
40 standard DOM interface for libxml2</a></li>
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]41</ul>
42
43<h2><a name="Introducti">Introduction</a></h2>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]44
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]45<p>This document describes libxml, the <a
Daniel Veillardec78c0f2000-08-25 10:25:23 +0000[diff] [blame]46href="http://www.w3.org/XML/">XML</a> C library developped for the <a
47href="http://www.gnome.org/">Gnome</a> project. <a
48href="http://www.w3.org/XML/">XML is a standard</a> for building tag-based
49structured documents/data.</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]50
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]51<p>Here are some key points about libxml:</p>
52<ul>
Daniel Veillard189446d2000-10-13 10:23:06 +0000[diff] [blame]53 <li>Libxml exports Push and Pull type parser interfaces for both XML and
54 HTML.</li>
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]55 <li>Libxml can do DTD validation at parse time, using a parsed document
56 instance, or with an arbitrary DTD.</li>
57 <li>Libxml now includes nearly complete <a
Daniel Veillard8c2ecaf2001-07-10 17:53:07 +0000[diff] [blame]58 href="http://www.w3.org/TR/xpath">XPath</a>, <a
59 href="http://www.w3.org/TR/xptr">XPointer</a> and <a
60 href="http://www.w3.org/TR/xinclude">XInclude</a> implementations.</li>
Daniel Veillardec78c0f2000-08-25 10:25:23 +0000[diff] [blame]61 <li>It is written in plain C, making as few assumptions as possible, and
Daniel Veillard189446d2000-10-13 10:23:06 +0000[diff] [blame]62 sticking closely to ANSI C/POSIX for easy embedding. Works on
Daniel Veillardab8500d2000-10-15 21:06:19 +0000[diff] [blame]63 Linux/Unix/Windows, ported to a number of other platforms.</li>
Daniel Veillardec70e912001-02-26 20:10:45 +0000[diff] [blame]64 <li>Basic support for HTTP and FTP client allowing aplications to fetch
65 remote resources</li>
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]66 <li>The design is modular, most of the extensions can be compiled out.</li>
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]67 <li>The internal document repesentation is as close as possible to the <a
68 href="http://www.w3.org/DOM/">DOM</a> interfaces.</li>
69 <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]70 like interface</a>; the interface is designed to be compatible with <a
71 href="http://www.jclark.com/xml/expat.html">Expat</a>.</li>
Daniel Veillardec303412000-03-24 13:41:54 +0000[diff] [blame]72 <li>This library is released both under the <a
73 href="http://www.w3.org/Consortium/Legal/copyright-software-19980720.html">W3C
Daniel Veillard189446d2000-10-13 10:23:06 +0000[diff] [blame]74 IPR</a> and the <a href="http://www.gnu.org/copyleft/lesser.html">GNU
75 LGPL</a>. Use either at your convenience, basically this should make
76 everybody happy, if not, drop me a mail.</li>
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]77</ul>
Daniel Veillardccb09631998-10-27 06:21:04 +0000[diff] [blame]78
Daniel Veillarde0c1d722001-03-21 10:28:36 +0000[diff] [blame]79<p>Warning: unless you are forced to because your application links with a
80Gnome library requiring it, <strong><span
81style="background-color: #FF0000">Do Not Use libxml1</span></strong>, use
82libxml2</p>
83
Daniel Veillardb8cfbd12001-10-25 10:53:28 +0000[diff] [blame^]84<h2><a name="FAQ">FAQ</a></h2>
85
86<p>Table of Content:</p>
87<ul>
88 <li><a href="FAQ.html#Licence">Licence(s)</a></li>
89 <li><a href="FAQ.html#Installati">Installation</a></li>
90 <li><a href="FAQ.html#Compilatio">Compilation</a></li>
91 <li><a href="FAQ.html#Developer">Developer corner</a></li>
92</ul>
93
94<h3><a name="Licence">Licence</a>(s)</h3>
95<ol>
96 <li><em>Licensing Terms for libxml</em>
97 <p>libxml is released under 2 (compatible) licences:</p>
98 <ul>
99 <li>the <a href="http://www.gnu.org/copyleft/lgpl.html">LGPL</a>: GNU
100 Library General Public License</li>
101 <li>the <a
102 href="http://www.w3.org/Consortium/Legal/copyright-software-19980720.html">W3C
103 IPR</a>: very similar to the XWindow licence</li>
104 </ul>
105 </li>
106 <li><em>Can I embed libxml in a proprietary application ?</em>
107 <p>Yes. The W3C IPR allows you to also keep proprietary the changes you
108 made to libxml, but it would be graceful to provide back bugfixes and
109 improvements as patches for possible incorporation in the main
110 development tree</p>
111 </li>
112</ol>
113
114<h3><a name="Installati">Installation</a></h3>
115<ol>
116 <li>Unless you are forced to because your application links with a Gnome
117 library requiring it, <strong><span style="background-color: #FF0000">Do
118 Not Use libxml1</span></strong>, use libxml2</li>
119 <li><em>Where can I get libxml</em>
120 ?
121 <p>The original distribution comes from <a
122 href="ftp://rpmfind.net/pub/libxml/">rpmfind.net</a> or <a
123 href="ftp://ftp.gnome.org/pub/GNOME/stable/sources/libxml/">gnome.org</a></p>
124 <p>Most linux and Bsd distribution includes libxml, this is probably the
125 safer way for end-users</p>
126 <p>David Doolin provides precompiled Windows versions at <a
127 href="http://www.ce.berkeley.edu/~doolin/code/libxmlwin32/ ">http://www.ce.berkeley.edu/~doolin/code/libxmlwin32/</a></p>
128 </li>
129 <li><em>I see libxml and libxml2 releases, which one should I install ?</em>
130 <ul>
131 <li>If you are not concerned by any existing backward compatibility
132 with existing application, install libxml2 only</li>
133 <li>If you are not doing development, you can safely install both.
134 usually the packages <a
135 href="http://rpmfind.net/linux/RPM/libxml.html">libxml</a> and <a
136 href="http://rpmfind.net/linux/RPM/libxml2.html">libxml2</a> are
137 compatible (this is not the case for development packages)</li>
138 <li>If you are a developer and your system provides separate packaging
139 for shared libraries and the development components, it is possible
140 to install libxml and libxml2, and also <a
141 href="http://rpmfind.net/linux/RPM/libxml-devel.html">libxml-devel</a>
142 and <a
143 href="http://rpmfind.net/linux/RPM/libxml2-devel.html">libxml2-devel</a>
144 too for libxml2 &gt;= 2.3.0</li>
145 <li>If you are developing a new application, please develop against
146 libxml2(-devel)</li>
147 </ul>
148 </li>
149 <li><em>I can't install the libxml package it conflicts with libxml0</em>
150 <p>You probably have an old libxml0 package used to provide the shared
151 library for libxml.so.0, you can probably safely remove it. Anyway the
152 libxml packages provided on <a
153 href="ftp://rpmfind.net/pub/libxml/">rpmfind.net</a> provides
154 libxml.so.0</p>
155 </li>
156 <li><em>I can't install the libxml(2) RPM package due to failed
157 dependancies</em>
158 <p>The most generic solution is to refetch the latest src.rpm , and
159 rebuild it locally with</p>
160 <p><code>rpm --rebuild libxml(2)-xxx.src.rpm</code></p>
161 <p>if everything goes well it will generate two binary rpm (one providing
162 the shared libs and xmllint, and the other one, the -devel package
163 providing includes, static libraries and scripts needed to build
164 applications with libxml(2)) that you can install locally.</p>
165 </li>
166</ol>
167
168<h3><a name="Compilatio">Compilation</a></h3>
169<ol>
170 <li><em>What is the process to compile libxml ?</em>
171 <p>As most UNIX libraries libxml follows the "standard":</p>
172 <p><code>gunzip -c xxx.tar.gz | tar xvf -</code></p>
173 <p><code>cd libxml-xxxx</code></p>
174 <p><code>./configure --help</code></p>
175 <p>to see the options, then the compilation/installation proper</p>
176 <p><code>./configure [possible options]</code></p>
177 <p><code>make</code></p>
178 <p><code>make install</code></p>
179 <p>At that point you may have to rerun ldconfig or similar utility to
180 update your list of installed shared libs.</p>
181 </li>
182 <li><em>What other libraries are needed to compile/install libxml ?</em>
183 <p>Libxml does not requires any other library, the normal C ANSI API
184 should be sufficient (please report any violation to this rule you may
185 find).</p>
186 <p>However if found at configuration time libxml will detect and use the
187 following libs:</p>
188 <ul>
189 <li><a href="http://www.info-zip.org/pub/infozip/zlib/">libz</a>
190 : a highly portable and available widely compression library</li>
191 <li>iconv: a powerful character encoding conversion library. It's
192 included by default on recent glibc libraries, so it doesn't need to
193 be installed specifically on linux. It seems it's now <a
194 href="http://www.opennc.org/onlinepubs/7908799/xsh/iconv.html">part
195 of the official UNIX</a> specification. Here is one <a
196 href="http://clisp.cons.org/~haible/packages-libiconv.html">implementation
197 of the library</a> which source can be found <a
198 href="ftp://ftp.ilog.fr/pub/Users/haible/gnu/">here</a>.</li>
199 </ul>
200 </li>
201 <li><em>libxml does not compile with HP-UX's optional ANSI-C compiler</em>
202 <p>this is due to macro limitations. Try to add " -Wp,-H16800 -Ae" to the
203 CFLAGS</p>
204 <p>you can also install and use gcc instead or use a precompiled version
205 of libxml, both available from the <a
206 href="http://hpux.cae.wisc.edu/hppd/auto/summary_all.html">HP-UX Porting
207 and Archive Centre</a></p>
208 </li>
209 <li><em>make check fails on some platforms</em>
210 <p>Sometime the regression tests results don't completely match the value
211 produced by the parser, and the makefile uses diff to print the delta. On
212 some platforms the diff return breaks the compilation process, if the
213 diff is small this is probably not a serious problem</p>
214 </li>
215 <li><em>I use the CVS version and there is no configure script</em>
216 <p>The configure (and other Makefiles) are generated. Use the autogen.sh
217 script to regenerate the configure and Makefiles, like:</p>
218 <p><code>./autogen.sh --prefix=/usr --disable-shared</code></p>
219 </li>
220 <li><em>I have troubles when running make tests with gcc-3.0</em>
221 <p>It seems the initial release of gcc-3.0 has a problem with the
222 optimizer which miscompiles the URI module. Please use another
223 compiler</p>
224 </li>
225</ol>
226
227<h3><a name="Developer">Developer</a> corner</h3>
228<ol>
229 <li><em>xmlDocDump() generates output on one line</em>
230 <p>libxml will not <strong>invent</strong> spaces in the content of a
231 document since <strong>all spaces in the content of a document are
232 significant</strong>. If you build a tree from the API and want
233 indentation:</p>
234 <ol>
235 <li>the correct way is to generate those yourself too</li>
236 <li>the dangerous way is to ask libxml to add those blanks to your
237 content <strong>modifying the content of your document in the
238 process</strong>. The result may not be what you expect. There is
239 <strong>NO</strong> way to guarantee that such a modification won't
240 impact other part of the content of your document. See <a
241 href="http://xmlsoft.org/html/libxml-parser.html#XMLKEEPBLANKSDEFAULT">xmlKeepBlanksDefault
242 ()</a> and <a
243 href="http://xmlsoft.org/html/libxml-tree.html#XMLSAVEFORMATFILE">xmlSaveFormatFile
244 ()</a></li>
245 </ol>
246 </li>
247 <li>Extra nodes in the document:
248 <p><em>For a XML file as below:</em></p>
249 <pre>&lt;?xml version="1.0"?&gt;
250&lt;PLAN xmlns="http://www.argus.ca/autotest/1.0/"&gt;
251&lt;NODE CommFlag="0"/&gt;
252&lt;NODE CommFlag="1"/&gt;
253&lt;/PLAN&gt;</pre>
254 <p><em>after parsing it with the function
255 pxmlDoc=xmlParseFile(...);</em></p>
256 <p><em>I want to the get the content of the first node (node with the
257 CommFlag="0")</em></p>
258 <p><em>so I did it as following;</em></p>
259 <pre>xmlNodePtr pode;
260pnode=pxmlDoc-&gt;children-&gt;children;</pre>
261 <p><em>but it does not work. If I change it to</em></p>
262 <pre>pnode=pxmlDoc-&gt;children-&gt;children-&gt;next;</pre>
263 <p><em>then it works. Can someone explain it to me.</em></p>
264 <p></p>
265 <p>In XML all characters in the content of the document are significant
266 <strong>including blanks and formatting line breaks</strong>.</p>
267 <p>The extra nodes you are wondering about are just that, text nodes with
268 the formatting spaces wich are part of the document but that people tend
269 to forget. There is a function <a
270 href="http://xmlsoft.org/html/libxml-parser.html">xmlKeepBlanksDefault
271 ()</a> to remove those at parse time, but that's an heuristic, and its
272 use should be limited to case where you are sure there is no
273 mixed-content in the document.</p>
274 </li>
275 <li><em>I get compilation errors of existing code like when accessing
276 <strong>root</strong> or <strong>childs fields</strong> of nodes</em>
277 <p>You are compiling code developed for libxml version 1 and using a
278 libxml2 development environment. Either switch back to libxml v1 devel or
279 even better fix the code to compile with libxml2 (or both) by <a
280 href="upgrade.html">following the instructions</a>.</p>
281 </li>
282 <li><em>I get compilation errors about non existing
283 <strong>xmlRootNode</strong> or <strong>xmlChildrenNode</strong>
284 fields</em>
285 <p>The source code you are using has been <a
286 href="upgrade.html">upgraded</a> to be able to compile with both libxml
287 and libxml2, but you need to install a more recent version:
288 libxml(-devel) &gt;= 1.8.8 or libxml2(-devel) &gt;= 2.1.0</p>
289 </li>
290 <li><em>XPath implementation looks seriously broken</em>
291 <p>XPath implementation prior to 2.3.0 was really incomplete, upgrade to
292 a recent version, the implementation and debug of libxslt generated fixes
293 for most obvious problems.</p>
294 </li>
295 <li><em>The example provided in the web page does not compile</em>
296 <p>It's hard to maintain the documentation in sync with the code
297 &lt;grin/&gt; ...</p>
298 <p>Check the previous points 1/ and 2/ raised before, and send
299 patches.</p>
300 </li>
301 <li><em>Where can I get more examples and informations than in the web
302 page</em>
303 <p>Ideally a libxml book would be nice. I have no such plan ... But you
304 can:</p>
305 <ul>
306 <li>check more deeply the <a href="html/libxml-lib.html">existing
307 generated doc</a></li>
308 <li>looks for examples of use for libxml function using the Gnome code
309 for example the following will query the full Gnome CVs base for the
310 use of the <strong>xmlAddChild()</strong> function:
311 <p><a
312 href="http://cvs.gnome.org/lxr/search?string=xmlAddChild">http://cvs.gnome.org/lxr/search?string=xmlAddChild</a></p>
313 <p>This may be slow, a large hardware donation to the gnome project
314 could cure this :-)</p>
315 </li>
316 <li><a
317 href="http://cvs.gnome.org/bonsai/rview.cgi?cvsroot=/cvs/gnome&amp;dir=gnome-xml">Browse
318 the libxml source</a>
319 , I try to write code as clean and documented as possible, so
320 looking at it may be helpful</li>
321 </ul>
322 </li>
323 <li>What about C++ ?
324 <p>libxml is written in pure C in order to allow easy reuse on a number
325 of platforms, including embedded systems. I don't intend to convert to
326 C++.</p>
327 <p>There is however a C++ wrapper provided by Ari Johnson
328 &lt;ari@btigate.com&gt; which may fullfill your needs:</p>
329 <p>Website: <a
330 href="http://lusis.org/~ari/xml++/">http://lusis.org/~ari/xml++/</a></p>
331 <p>Download: <a
332 href="http://lusis.org/~ari/xml++/libxml++.tar.gz">http://lusis.org/~ari/xml++/libxml++.tar.gz</a></p>
333 </li>
334 <li>How to validate a document a posteriori ?
335 <p>It is possible to validate documents which had not been validated at
336 initial parsing time or documents who have been built from scratch using
337 the API. Use the <a
338 href="http://xmlsoft.org/html/libxml-valid.html#XMLVALIDATEDTD">xmlValidateDtd()</a>
339 function. It is also possible to simply add a Dtd to an existing
340 document:</p>
341 <pre>xmlDocPtr doc; /* your existing document */
342 xmlDtdPtr dtd = xmlParseDTD(NULL, filename_of_dtd); /* parse the DTD */
343 dtd-&gt;name = xmlStrDup((xmlChar*)"root_name"); /* use the given root */
344
345 doc-&gt;intSubset = dtd;
346 if (doc-&gt;children == NULL) xmlAddChild((xmlNodePtr)doc, (xmlNodePtr)dtd);
347 else xmlAddPrevSibling(doc-&gt;children, (xmlNodePtr)dtd);
348 </pre>
349 </li>
350 <li>etc ...</li>
351</ol>
352
353<p></p>
354
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]355<h2><a name="Documentat">Documentation</a></h2>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]356
Daniel Veillard402e8c82000-02-29 22:57:47 +0000[diff] [blame]357<p>There are some on-line resources about using libxml:</p>
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]358<ol>
Daniel Veillard365e13b2000-07-02 07:56:37 +0000[diff] [blame]359 <li>Check the <a href="FAQ.html">FAQ</a></li>
Daniel Veillardc19fccc2000-07-03 11:52:01 +0000[diff] [blame]360 <li>Check the <a href="http://xmlsoft.org/html/libxml-lib.html">extensive
Daniel Veillard8c6d6af2000-08-25 17:14:13 +0000[diff] [blame]361 documentation</a> automatically extracted from code comments (using <a
362 href="http://cvs.gnome.org/bonsai/rview.cgi?cvsroot=/cvs/gnome&amp;dir=gtk-doc">gtk
363 doc</a>).</li>
Daniel Veillard8d869642000-07-14 12:12:59 +0000[diff] [blame]364 <li>Look at the documentation about <a href="encoding.html">libxml
365 internationalization support</a></li>
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]366 <li>This page provides a global overview and <a href="#real">some
Daniel Veillard402e8c82000-02-29 22:57:47 +0000[diff] [blame]367 examples</a> on how to use libxml.</li>
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]368 <li><a href="mailto:james@daa.com.au">James Henstridge</a>
369 wrote <a
Daniel Veillard402e8c82000-02-29 22:57:47 +0000[diff] [blame]370 href="http://www.daa.com.au/~james/gnome/xml-sax/xml-sax.html">some nice
371 documentation</a> explaining how to use the libxml SAX interface.</li>
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]372 <li>George Lebl wrote <a
373 href="http://www-4.ibm.com/software/developer/library/gnome3/">an article
Daniel Veillard402e8c82000-02-29 22:57:47 +0000[diff] [blame]374 for IBM developerWorks</a> about using libxml.</li>
Daniel Veillardec303412000-03-24 13:41:54 +0000[diff] [blame]375 <li>Check <a href="http://cvs.gnome.org/lxr/source/gnome-xml/TODO">the TODO
376 file</a></li>
377 <li>Read the <a href="upgrade.html">1.x to 2.x upgrade path</a>. If you are
378 starting a new project using libxml you should really use the 2.x
379 version.</li>
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]380 <li>And don't forget to look at the <a href="/messages/">mailing-list
Daniel Veillardc310d562000-06-23 18:32:15 +0000[diff] [blame]381 archive</a>.</li>
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]382</ol>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]383
Daniel Veillardd5f97f82000-09-17 16:38:14 +0000[diff] [blame]384<h2><a name="Reporting">Reporting bugs and getting help</a></h2>
Daniel Veillard4c3a2031999-11-19 17:46:26 +0000[diff] [blame]385
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]386<p>Well, bugs or missing features are always possible, and I will make a
387point of fixing them in a timely fashion. The best way to report a bug is to
388use the <a href="http://bugzilla.gnome.org/buglist.cgi?product=libxml">Gnome
389bug tracking database</a> (make sure to use the "libxml" module name). I look
390at reports there regularly and it's good to have a reminder when a bug is
391still open. Check the <a
392href="http://bugzilla.gnome.org/bugwritinghelp.html">instructions on
393reporting bugs</a> and be sure to specify that the bug is for the package
394libxml.</p>
Daniel Veillard4c3a2031999-11-19 17:46:26 +0000[diff] [blame]395
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]396<p>There is also a mailing-list <a
Daniel Veillard3197f162001-04-04 00:40:08 +0000[diff] [blame]397href="mailto:xml@gnome.org">xml@gnome.org</a> for libxml, with an <a
398href="http://mail.gnome.org/archives/xml/">on-line archive</a> (<a
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]399href="http://xmlsoft.org/messages">old</a>). To subscribe to this list,
400please visit the <a
401href="http://mail.gnome.org/mailman/listinfo/xml">associated Web</a> page and
402follow the instructions. <strong>Do not send code, I won't debug it</strong>
403(but patches are really appreciated!).</p>
Daniel Veillard234547b2001-07-05 09:46:10 +0000[diff] [blame]404
Daniel Veillard008186f2001-09-13 14:24:44 +0000[diff] [blame]405<p>Check the following <strong><span style="color: #FF0000">before
406posting</span></strong>:</p>
Daniel Veillard234547b2001-07-05 09:46:10 +0000[diff] [blame]407<ul>
Daniel Veillarddadd0872001-09-15 09:21:44 +0000[diff] [blame]408 <li>read the <a href="FAQ.html">FAQ</a></li>
Daniel Veillard234547b2001-07-05 09:46:10 +0000[diff] [blame]409 <li>make sure you are <a href="ftp://xmlsoft.org/">using a recent
410 version</a>, and that the problem still shows up in those</li>
411 <li>check the <a href="http://mail.gnome.org/archives/xml/">list
412 archives</a> to see if the problem was reported already, in this case
Daniel Veillarde7ead2d2001-08-22 23:44:09 +0000[diff] [blame]413 there is probably a fix available, similary check the <a
414 href="http://bugzilla.gnome.org/buglist.cgi?product=libxml">registered
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]415 open bugs</a></li>
Daniel Veillard234547b2001-07-05 09:46:10 +0000[diff] [blame]416 <li>make sure you can reproduce the bug with xmllint or one of the test
417 programs found in source in the distribution</li>
418 <li>Please send the command showing the error as well as the input (as an
419 attachement)</li>
420</ul>
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]421
Daniel Veillarddadd0872001-09-15 09:21:44 +0000[diff] [blame]422<p>Then send the bug with associated informations to reproduce it to the <a
Daniel Veillard33a67802001-03-07 09:44:02 +0000[diff] [blame]423href="mailto:xml@gnome.org">xml@gnome.org</a> list; if it's really libxml
Daniel Veillard008186f2001-09-13 14:24:44 +0000[diff] [blame]424related I will approve it.. Please do not send me mail directly, it makes
425things really harder to track and in some cases I'm not the best person to
426answer a given question, ask the list instead.</p>
Daniel Veillard4c3a2031999-11-19 17:46:26 +0000[diff] [blame]427
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]428<p>Of course, bugs reported with a suggested patch for fixing them will
Daniel Veillardec303412000-03-24 13:41:54 +0000[diff] [blame]429probably be processed faster.</p>
430
431<p>If you're looking for help, a quick look at <a
Daniel Veillardf7ed3362001-08-17 12:01:21 +0000[diff] [blame]432href="http://mail.gnome.org/archives/xml/">the list archive</a> may actually
Daniel Veillardec303412000-03-24 13:41:54 +0000[diff] [blame]433provide the answer, I usually send source samples when answering libxml usage
Daniel Veillard6f0adb52000-07-03 11:41:26 +0000[diff] [blame]434questions. The <a href="http://xmlsoft.org/html/book1.html">auto-generated
Daniel Veillardec303412000-03-24 13:41:54 +0000[diff] [blame]435documentantion</a> is not as polished as I would like (i need to learn more
436about Docbook), but it's a good starting point.</p>
437
Daniel Veillardd5f97f82000-09-17 16:38:14 +0000[diff] [blame]438<h2><a name="help">How to help</a></h2>
439
440<p>You can help the project in various ways, the best thing to do first is to
441subscribe to the mailing-list as explained before, check the <a
Daniel Veillardf7ed3362001-08-17 12:01:21 +0000[diff] [blame]442href="http://mail.gnome.org/archives/xml/">archives </a>and the <a
443href="http://bugzilla.gnome.org/buglist.cgi?product=libxml">Gnome bug
Daniel Veillardd5f97f82000-09-17 16:38:14 +0000[diff] [blame]444database:</a>:</p>
445<ol>
446 <li>provide patches when you find problems</li>
Daniel Veillard189446d2000-10-13 10:23:06 +0000[diff] [blame]447 <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]448 be integrated in all cases but help pinpointing portability problems
449 and</li>
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]450 <li>provide documentation fixes (either as patches to the code comments or
Daniel Veillardd5f97f82000-09-17 16:38:14 +0000[diff] [blame]451 as HTML diffs).</li>
452 <li>provide new documentations pieces (translations, examples, etc ...)</li>
453 <li>Check the TODO file and try to close one of the items</li>
454 <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]455 provide a fix. <a href="mailto:daniel@veillard.com">Get in touch with me
456 </a>before to avoid synchronization problems and check that the suggested
457 fix will fit in nicely :-)</li>
Daniel Veillardd5f97f82000-09-17 16:38:14 +0000[diff] [blame]458</ol>
459
Daniel Veillard10a2c651999-12-12 13:03:50 +0000[diff] [blame]460<h2><a name="Downloads">Downloads</a></h2>
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]461
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]462<p>The latest versions of libxml can be found on <a
Daniel Veillard20c8cf22001-06-26 22:47:36 +0000[diff] [blame]463href="ftp://xmlsoft.org/">xmlsoft.org</a> (<a
464href="ftp://speakeasy.rpmfind.net/pub/libxml/">Seattle</a>, <a
465href="ftp://fr.rpmfind.net/pub/libxml/">France</a>) or on the <a
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]466href="ftp://ftp.gnome.org/pub/GNOME/MIRRORS.html">Gnome FTP server</a> either
Daniel Veillard10a2c651999-12-12 13:03:50 +0000[diff] [blame]467as a <a href="ftp://ftp.gnome.org/pub/GNOME/stable/sources/libxml/">source
Daniel Veillard306be992000-07-03 12:38:45 +0000[diff] [blame]468archive</a> or <a
Daniel Veillarda41123c2001-04-22 19:31:20 +0000[diff] [blame]469href="ftp://ftp.gnome.org/pub/GNOME/stable/redhat/i386/libxml/">RPM
470packages</a>. (NOTE that you need both the <a
Daniel Veillardc19fccc2000-07-03 11:52:01 +0000[diff] [blame]471href="http://rpmfind.net/linux/RPM/libxml2.html">libxml(2)</a> and <a
472href="http://rpmfind.net/linux/RPM/libxml2-devel.html">libxml(2)-devel</a>
Daniel Veillard95189532001-07-26 18:30:26 +0000[diff] [blame]473packages installed to compile applications using libxml.) <a
474href="mailto:izlatkovic@daenet.de">Igor Zlatkovic</a> is now the maintainer
475of the Windows port, <a
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]476href="http://www.fh-frankfurt.de/~igor/projects/libxml/index.html">he
477provides binaries</a></p>
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]478
Daniel Veillard6c8b1172000-03-01 00:40:41 +0000[diff] [blame]479<p><a name="Snapshot">Snapshot:</a></p>
480<ul>
481 <li>Code from the W3C cvs base libxml <a
Daniel Veillard33a67802001-03-07 09:44:02 +0000[diff] [blame]482 href="ftp://xmlsoft.org/cvs-snapshot.tar.gz">cvs-snapshot.tar.gz</a></li>
Daniel Veillard6c8b1172000-03-01 00:40:41 +0000[diff] [blame]483 <li>Docs, content of the web site, the list archive included <a
Daniel Veillard33a67802001-03-07 09:44:02 +0000[diff] [blame]484 href="ftp://xmlsoft.org/libxml-docs.tar.gz">libxml-docs.tar.gz</a></li>
Daniel Veillard6c8b1172000-03-01 00:40:41 +0000[diff] [blame]485</ul>
486
487<p><a name="Contribs">Contribs:</a></p>
488
489<p>I do accept external contributions, especially if compiling on another
490platform, get in touch with me to upload the package. I will keep them in the
Daniel Veillard33a67802001-03-07 09:44:02 +0000[diff] [blame]491<a href="ftp://xmlsoft.org/contribs/">contrib directory</a></p>
Daniel Veillard6c8b1172000-03-01 00:40:41 +0000[diff] [blame]492
Daniel Veillard82687162001-01-22 15:32:01 +0000[diff] [blame]493<p>Libxml is also available from CVS:</p>
Daniel Veillard10a2c651999-12-12 13:03:50 +0000[diff] [blame]494<ul>
Daniel Veillard10a2c651999-12-12 13:03:50 +0000[diff] [blame]495 <li><p>The <a
496 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]497 CVS base</a>. Check the <a
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]498 href="http://developer.gnome.org/tools/cvs.html">Gnome CVS Tools</a>
499 page; the CVS module is <b>gnome-xml</b>.</p>
Daniel Veillard10a2c651999-12-12 13:03:50 +0000[diff] [blame]500 </li>
Daniel Veillard82687162001-01-22 15:32:01 +0000[diff] [blame]501 <li>The <strong>libxslt</strong> module is also present there</li>
Daniel Veillard10a2c651999-12-12 13:03:50 +0000[diff] [blame]502</ul>
503
504<h2><a name="News">News</a></h2>
505
Daniel Veillard944b5ff1999-12-15 19:08:24 +0000[diff] [blame]506<h3>CVS only : check the <a
507href="http://cvs.gnome.org/lxr/source/gnome-xml/ChangeLog">Changelog</a> file
Daniel Veillard189446d2000-10-13 10:23:06 +0000[diff] [blame]508for a really accurate description</h3>
Daniel Veillardab8500d2000-10-15 21:06:19 +0000[diff] [blame]509
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]510<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]511you want to test those</p>
512<ul>
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]513 <li>Implementing <a href="http://xmlsoft.org/XSLT">XSLT</a>, this is done
514 as a separate C library on top of libxml called libxslt</li>
Daniel Veillard28929b22000-11-13 18:22:49 +0000[diff] [blame]515 <li>Finishing up <a href="http://www.w3.org/TR/xptr">XPointer</a> and <a
516 href="http://www.w3.org/TR/xinclude">XInclude</a></li>
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]517 <li>(seeems working but delayed from release) parsing/import of Docbook
518 SGML docs</li>
519</ul>
520
Daniel Veillard60087f32001-10-10 09:45:09 +0000[diff] [blame]521<h3>2.4.6: Oct 10 2001</h3>
522<ul>
523 <li>added and updated man pages by John Fleck</li>
524 <li>portability and configure fixes</li>
525 <li>an infinite loop on the HTML parser was removed (William)</li>
526 <li>Windows makefile patches from Igor</li>
527 <li>fixed half a dozen bugs reported fof libxml or libxslt</li>
528 <li>updated xmlcatalog to be able to modify SGML super catalogs</li>
529</ul>
530
Daniel Veillarddadd0872001-09-15 09:21:44 +0000[diff] [blame]531<h3>2.4.5: Sep 14 2001</h3>
532<ul>
533 <li>Remove a few annoying bugs in 2.4.4</li>
534 <li>forces the HTML serializer to output decimal charrefs since some
535 version of Netscape can't handle hexadecimal ones</li>
536</ul>
537
538<h3>1.8.16: Sep 14 2001</h3>
539<ul>
540 <li>maintenance release of the old libxml1 branch, couple of bug and
541 portability fixes</li>
542</ul>
543
Daniel Veillard04382ae2001-09-12 18:51:30 +0000[diff] [blame]544<h3>2.4.4: Sep 12 2001</h3>
545<ul>
546 <li>added --convert to xmlcatalog, bug fixes and cleanups of XML
547 Catalog</li>
548 <li>a few bug fixes and some portability changes</li>
549 <li>some documentation cleanups</li>
550</ul>
551
Daniel Veillard39936902001-08-24 00:49:01 +0000[diff] [blame]552<h3>2.4.3: Aug 23 2001</h3>
553<ul>
554 <li>XML Catalog support see the doc</li>
555 <li>New NaN/Infinity floating point code</li>
556 <li>A few bug fixes</li>
557</ul>
558
559<h3>2.4.2: Aug 15 2001</h3>
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]560<ul>
561 <li>adds xmlLineNumbersDefault() to control line number generation</li>
562 <li>lot of bug fixes</li>
563 <li>the Microsoft MSC projects files shuld now be up to date</li>
564 <li>inheritance of namespaces from DTD defaulted attributes</li>
565 <li>fixes a serious potential security bug</li>
566 <li>added a --format option to xmllint</li>
567</ul>
568
569<h3>2.4.1: July 24 2001</h3>
570<ul>
571 <li>possibility to keep line numbers in the tree</li>
572 <li>some computation NaN fixes</li>
573 <li>extension of the XPath API</li>
574 <li>cleanup for alpha and ia64 targets</li>
575 <li>patch to allow saving through HTTP PUT or POST</li>
Daniel Veillard09ab7e12001-07-10 15:49:44 +0000[diff] [blame]576</ul>
577
578<h3>2.4.0: July 10 2001</h3>
579<ul>
580 <li>Fixed a few bugs in XPath, validation, and tree handling.</li>
581 <li>Fixed XML Base implementation, added a coupel of examples to the
582 regression tests</li>
583 <li>A bit of cleanup</li>
Daniel Veillardab8500d2000-10-15 21:06:19 +0000[diff] [blame]584</ul>
585
Daniel Veillard5b43fde2001-07-05 23:31:40 +0000[diff] [blame]586<h3>2.3.14: July 5 2001</h3>
587<ul>
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]588 <li>fixed some entities problems and reduce mem requirement when
589 substituing them</li>
Daniel Veillard5b43fde2001-07-05 23:31:40 +0000[diff] [blame]590 <li>lots of improvements in the XPath queries interpreter can be
591 substancially faster</li>
592 <li>Makefiles and configure cleanups</li>
593 <li>Fixes to XPath variable eval, and compare on empty node set</li>
594 <li>HTML tag closing bug fixed</li>
595 <li>Fixed an URI reference computating problem when validating</li>
596</ul>
597
Daniel Veillard2adbb512001-06-28 16:20:36 +0000[diff] [blame]598<h3>2.3.13: June 28 2001</h3>
599<ul>
600 <li>2.3.12 configure.in was broken as well as the push mode XML parser</li>
601 <li>a few more fixes for compilation on Windows MSC by Yon Derek</li>
602</ul>
603
604<h3>1.8.14: June 28 2001</h3>
605<ul>
606 <li>Zbigniew Chyla gave a patch to use the old XML parser in push mode</li>
607 <li>Small Makefile fix</li>
608</ul>
609
Daniel Veillard11648102001-06-26 16:08:24 +0000[diff] [blame]610<h3>2.3.12: June 26 2001</h3>
611<ul>
612 <li>lots of cleanup</li>
613 <li>a couple of validation fix</li>
614 <li>fixed line number counting</li>
615 <li>fixed serious problems in the XInclude processing</li>
616 <li>added support for UTF8 BOM at beginning of entities</li>
617 <li>fixed a strange gcc optimizer bugs in xpath handling of float, gcc-3.0
618 miscompile uri.c (William), Thomas Leitner provided a fix for the
619 optimizer on Tru64</li>
620 <li>incorporated Yon Derek and Igor Zlatkovic fixes and improvements for
621 compilation on Windows MSC</li>
622 <li>update of libxml-doc.el (Felix Natter)</li>
623 <li>fixed 2 bugs in URI normalization code</li>
624</ul>
625
Daniel Veillarde3c81b52001-06-17 14:50:34 +0000[diff] [blame]626<h3>2.3.11: June 17 2001</h3>
627<ul>
628 <li>updates to trio, Makefiles and configure should fix some portability
629 problems (alpha)</li>
630 <li>fixed some HTML serialization problems (pre, script, and block/inline
631 handling), added encoding aware APIs, cleanup of this code</li>
632 <li>added xmlHasNsProp()</li>
633 <li>implemented a specific PI for encoding support in the DocBook SGML
634 parser</li>
635 <li>some XPath fixes (-Infinity, / as a function parameter and namespaces
636 node selection)</li>
637 <li>fixed a performance problem and an error in the validation code</li>
638 <li>fixed XInclude routine to implement the recursive behaviour</li>
639 <li>fixed xmlFreeNode problem when libxml is included statically twice</li>
640 <li>added --version to xmllint for bug reports</li>
641</ul>
642
Daniel Veillard2e4f1882001-06-01 10:11:57 +0000[diff] [blame]643<h3>2.3.10: June 1 2001</h3>
644<ul>
645 <li>fixed the SGML catalog support</li>
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]646 <li>a number of reported bugs got fixed, in XPath, iconv detection,
647 XInclude processing</li>
Daniel Veillard2e4f1882001-06-01 10:11:57 +0000[diff] [blame]648 <li>XPath string function should now handle unicode correctly</li>
649</ul>
650
Daniel Veillard4623acd2001-05-19 15:13:15 +0000[diff] [blame]651<h3>2.3.9: May 19 2001</h3>
652
653<p>Lots of bugfixes, and added a basic SGML catalog support:</p>
654<ul>
655 <li>HTML push bugfix #54891 and another patch from Jonas Borgström</li>
656 <li>some serious speed optimisation again</li>
657 <li>some documentation cleanups</li>
658 <li>trying to get better linking on solaris (-R)</li>
659 <li>XPath API cleanup from Thomas Broyer</li>
660 <li>Validation bug fixed #54631, added a patch from Gary Pennington, fixed
661 xmlValidGetValidElements()</li>
662 <li>Added an INSTALL file</li>
663 <li>Attribute removal added to API: #54433</li>
664 <li>added a basic support for SGML catalogs</li>
665 <li>fixed xmlKeepBlanksDefault(0) API</li>
666 <li>bugfix in xmlNodeGetLang()</li>
667 <li>fixed a small configure portability problem</li>
668 <li>fixed an inversion of SYSTEM and PUBLIC identifier in HTML document</li>
669</ul>
670
Daniel Veillarda265af72001-05-14 11:13:58 +0000[diff] [blame]671<h3>1.8.13: May 14 2001</h3>
672<ul>
673 <li>bugfixes release of the old libxml1 branch used by Gnome</li>
674</ul>
675
Daniel Veillard3bbbe6f2001-05-03 11:15:37 +0000[diff] [blame]676<h3>2.3.8: May 3 2001</h3>
677<ul>
678 <li>Integrated an SGML DocBook parser for the Gnome project</li>
679 <li>Fixed a few things in the HTML parser</li>
680 <li>Fixed some XPath bugs raised by XSLT use, tried to fix the floating
681 point portability issue</li>
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]682 <li>Speed improvement (8M/s for SAX, 3M/s for DOM, 1.5M/s for
683 DOM+validation using the XML REC as input and a 700MHz celeron).</li>
Daniel Veillard3bbbe6f2001-05-03 11:15:37 +0000[diff] [blame]684 <li>incorporated more Windows cleanup</li>
685 <li>added xmlSaveFormatFile()</li>
686 <li>fixed problems in copying nodes with entities references (gdome)</li>
687 <li>removed some troubles surrounding the new validation module</li>
688</ul>
689
Daniel Veillarda41123c2001-04-22 19:31:20 +0000[diff] [blame]690<h3>2.3.7: April 22 2001</h3>
691<ul>
692 <li>lots of small bug fixes, corrected XPointer</li>
693 <li>Non determinist content model validation support</li>
694 <li>added xmlDocCopyNode for gdome2</li>
695 <li>revamped the way the HTML parser handles end of tags</li>
696 <li>XPath: corrctions of namespacessupport and number formatting</li>
697 <li>Windows: Igor Zlatkovic patches for MSC compilation</li>
698 <li>HTML ouput fixes from P C Chow and William M. Brack</li>
699 <li>Improved validation speed sensible for DocBook</li>
700 <li>fixed a big bug with ID declared in external parsed entities</li>
701 <li>portability fixes, update of Trio from Bjorn Reese</li>
702</ul>
703
Daniel Veillardafc73112001-04-11 11:51:41 +0000[diff] [blame]704<h3>2.3.6: April 8 2001</h3>
705<ul>
706 <li>Code cleanup using extreme gcc compiler warning options, found and
707 cleared half a dozen potential problem</li>
708 <li>the Eazel team found an XML parser bug</li>
709 <li>cleaned up the user of some of the string formatting function. used the
710 trio library code to provide the one needed when the platform is missing
711 them</li>
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]712 <li>xpath: removed a memory leak and fixed the predicate evaluation
713 problem, extended the testsuite and cleaned up the result. XPointer seems
714 broken ...</li>
Daniel Veillardafc73112001-04-11 11:51:41 +0000[diff] [blame]715</ul>
716
Daniel Veillard56a4cb82001-03-24 17:00:36 +0000[diff] [blame]717<h3>2.3.5: Mar 23 2001</h3>
718<ul>
719 <li>Biggest change is separate parsing and evaluation of XPath expressions,
720 there is some new APIs for this too</li>
721 <li>included a number of bug fixes(XML push parser, 51876, notations,
722 52299)</li>
723 <li>Fixed some portability issues</li>
724</ul>
725
Daniel Veillarde356c282001-03-10 12:32:04 +0000[diff] [blame]726<h3>2.3.4: Mar 10 2001</h3>
727<ul>
728 <li>Fixed bugs #51860 and #51861</li>
729 <li>Added a global variable xmlDefaultBufferSize to allow default buffer
730 size to be application tunable.</li>
731 <li>Some cleanup in the validation code, still a bug left and this part
732 should probably be rewritten to support ambiguous content model :-\</li>
733 <li>Fix a couple of serious bugs introduced or raised by changes in 2.3.3
734 parser</li>
735 <li>Fixed another bug in xmlNodeGetContent()</li>
736 <li>Bjorn fixed XPath node collection and Number formatting</li>
737 <li>Fixed a loop reported in the HTML parsing</li>
738 <li>blank space are reported even if the Dtd content model proves that they
739 are formatting spaces, this is for XmL conformance</li>
740</ul>
741
Daniel Veillardb402c072001-03-01 17:28:58 +0000[diff] [blame]742<h3>2.3.3: Mar 1 2001</h3>
743<ul>
744 <li>small change in XPath for XSLT</li>
745 <li>documentation cleanups</li>
746 <li>fix in validation by Gary Pennington</li>
747 <li>serious parsing performances improvements</li>
748</ul>
749
Daniel Veillardec70e912001-02-26 20:10:45 +0000[diff] [blame]750<h3>2.3.2: Feb 24 2001</h3>
Daniel Veillard71681102001-02-24 17:48:53 +0000[diff] [blame]751<ul>
752 <li>chasing XPath bugs, found a bunch, completed some TODO</li>
753 <li>fixed a Dtd parsing bug</li>
754 <li>fixed a bug in xmlNodeGetContent</li>
755 <li>ID/IDREF support partly rewritten by Gary Pennington</li>
756</ul>
757
Daniel Veillardec70e912001-02-26 20:10:45 +0000[diff] [blame]758<h3>2.3.1: Feb 15 2001</h3>
Daniel Veillard6e6a6cc2001-02-15 15:55:44 +0000[diff] [blame]759<ul>
760 <li>some XPath and HTML bug fixes for XSLT</li>
761 <li>small extension of the hash table interfaces for DOM gdome2
762 implementation</li>
763 <li>A few bug fixes</li>
764</ul>
765
Daniel Veillardec70e912001-02-26 20:10:45 +0000[diff] [blame]766<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]767<ul>
768 <li>Lots of XPath bug fixes</li>
769 <li>Add a mode with Dtd lookup but without validation error reporting for
770 XSLT</li>
771 <li>Add support for text node without escaping (XSLT)</li>
772 <li>bug fixes for xmlCheckFilename</li>
773 <li>validation code bug fixes from Gary Pennington</li>
774 <li>Patch from Paul D. Smith correcting URI path normalization</li>
775 <li>Patch to allow simultaneous install of libxml-devel and
776 libxml2-devel</li>
777 <li>the example Makefile is now fixed</li>
778 <li>added HTML to the RPM packages</li>
779 <li>tree copying bugfixes</li>
780 <li>updates to Windows makefiles</li>
781 <li>optimisation patch from Bjorn Reese</li>
782</ul>
783
Daniel Veillardec70e912001-02-26 20:10:45 +0000[diff] [blame]784<h3>2.2.11: Jan 4 2001</h3>
Daniel Veillard503b8932001-01-05 06:36:31 +0000[diff] [blame]785<ul>
786 <li>bunch of bug fixes (memory I/O, xpath, ftp/http, ...)</li>
787 <li>added htmlHandleOmittedElem()</li>
788 <li>Applied Bjorn Reese's IPV6 first patch</li>
789 <li>Applied Paul D. Smith patches for validation of XInclude results</li>
Daniel Veillard82687162001-01-22 15:32:01 +0000[diff] [blame]790 <li>added XPointer xmlns() new scheme support</li>
Daniel Veillard503b8932001-01-05 06:36:31 +0000[diff] [blame]791</ul>
792
Daniel Veillard2ddd23d2000-11-25 10:42:19 +0000[diff] [blame]793<h3>2.2.10: Nov 25 2000</h3>
Daniel Veillard9d343c42000-11-25 10:12:43 +0000[diff] [blame]794<ul>
795 <li>Fix the Windows problems of 2.2.8</li>
796 <li>integrate OpenVMS patches</li>
797 <li>better handling of some nasty HTML input</li>
798 <li>Improved the XPointer implementation</li>
799 <li>integrate a number of provided patches</li>
800</ul>
801
Daniel Veillard2ddd23d2000-11-25 10:42:19 +0000[diff] [blame]802<h3>2.2.9: Nov 25 2000</h3>
803<ul>
804 <li>erroneous release :-(</li>
805</ul>
806
Daniel Veillard28929b22000-11-13 18:22:49 +0000[diff] [blame]807<h3>2.2.8: Nov 13 2000</h3>
808<ul>
809 <li>First version of <a href="http://www.w3.org/TR/xinclude">XInclude</a>
810 support</li>
811 <li>Patch in conditional section handling</li>
812 <li>updated MS compiler project</li>
813 <li>fixed some XPath problems</li>
814 <li>added an URI escaping function</li>
815 <li>some other bug fixes</li>
816</ul>
817
818<h3>2.2.7: Oct 31 2000</h3>
819<ul>
820 <li>added message redirection</li>
821 <li>XPath improvements (thanks TOM !)</li>
822 <li>xmlIOParseDTD() added</li>
823 <li>various small fixes in the HTML, URI, HTTP and XPointer support</li>
824 <li>some cleanup of the Makefile, autoconf and the distribution content</li>
825</ul>
826
Daniel Veillard29a11cc2000-10-25 13:32:39 +0000[diff] [blame]827<h3>2.2.6: Oct 25 2000:</h3>
828<ul>
829 <li>Added an hash table module, migrated a number of internal structure to
830 those</li>
831 <li>Fixed a posteriori validation problems</li>
832 <li>HTTP module cleanups</li>
833 <li>HTML parser improvements (tag errors, script/style handling, attribute
834 normalization)</li>
835 <li>coalescing of adjacent text nodes</li>
836 <li>couple of XPath bug fixes, exported the internal API</li>
837</ul>
838
Daniel Veillardab8500d2000-10-15 21:06:19 +0000[diff] [blame]839<h3>2.2.5: Oct 15 2000:</h3>
Daniel Veillard4c3a2031999-11-19 17:46:26 +0000[diff] [blame]840<ul>
Daniel Veillard189446d2000-10-13 10:23:06 +0000[diff] [blame]841 <li>XPointer implementation and testsuite</li>
842 <li>Lot of XPath fixes, added variable and functions registration, more
843 tests</li>
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]844 <li>Portability fixes, lots of enhancements toward an easy Windows build
845 and release</li>
Daniel Veillard189446d2000-10-13 10:23:06 +0000[diff] [blame]846 <li>Late validation fixes</li>
847 <li>Integrated a lot of contributed patches</li>
848 <li>added memory management docs</li>
Daniel Veillardab8500d2000-10-15 21:06:19 +0000[diff] [blame]849 <li>a performance problem when using large buffer seems fixed</li>
Daniel Veillard189446d2000-10-13 10:23:06 +0000[diff] [blame]850</ul>
851
852<h3>2.2.4: Oct 1 2000:</h3>
853<ul>
854 <li>main XPath problem fixed</li>
855 <li>Integrated portability patches for Windows</li>
856 <li>Serious bug fixes on the URI and HTML code</li>
Daniel Veillard361d8452000-04-03 19:48:13 +0000[diff] [blame]857</ul>
858
Daniel Veillardd5f97f82000-09-17 16:38:14 +0000[diff] [blame]859<h3>2.2.3: Sep 17 2000</h3>
860<ul>
861 <li>bug fixes</li>
862 <li>cleanup of entity handling code</li>
863 <li>overall review of all loops in the parsers, all sprintf usage has been
864 checked too</li>
865 <li>Far better handling of larges Dtd. Validating against Docbook XML Dtd
866 works smoothly now.</li>
867</ul>
868
869<h3>1.8.10: Sep 6 2000</h3>
870<ul>
871 <li>bug fix release for some Gnome projects</li>
872</ul>
873
874<h3>2.2.2: August 12 2000</h3>
Daniel Veillard786d7c82000-08-12 23:38:57 +0000[diff] [blame]875<ul>
876 <li>mostly bug fixes</li>
Daniel Veillardec78c0f2000-08-25 10:25:23 +0000[diff] [blame]877 <li>started adding routines to access xml parser context options</li>
Daniel Veillard786d7c82000-08-12 23:38:57 +0000[diff] [blame]878</ul>
879
Daniel Veillardd5f97f82000-09-17 16:38:14 +0000[diff] [blame]880<h3>2.2.1: July 21 2000</h3>
Daniel Veillarda2679fa2000-07-22 02:38:15 +0000[diff] [blame]881<ul>
882 <li>a purely bug fixes release</li>
883 <li>fixed an encoding support problem when parsing from a memory block</li>
884 <li>fixed a DOCTYPE parsing problem</li>
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]885 <li>removed a bug in the function allowing to override the memory
886 allocation routines</li>
Daniel Veillarda2679fa2000-07-22 02:38:15 +0000[diff] [blame]887</ul>
888
Daniel Veillardd5f97f82000-09-17 16:38:14 +0000[diff] [blame]889<h3>2.2.0: July 14 2000</h3>
Daniel Veillard94e90602000-07-17 14:38:19 +0000[diff] [blame]890<ul>
891 <li>applied a lot of portability fixes</li>
892 <li>better encoding support/cleanup and saving (content is now always
893 encoded in UTF-8)</li>
894 <li>the HTML parser now correctly handles encodings</li>
895 <li>added xmlHasProp()</li>
896 <li>fixed a serious problem with &amp;#38;</li>
897 <li>propagated the fix to FTP client</li>
898 <li>cleanup, bugfixes, etc ...</li>
899 <li>Added a page about <a href="encoding.html">libxml Internationalization
900 support</a></li>
901</ul>
902
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]903<h3>1.8.9: July 9 2000</h3>
904<ul>
905 <li>fixed the spec the RPMs should be better</li>
906 <li>fixed a serious bug in the FTP implementation, released 1.8.9 to solve
907 rpmfind users problem</li>
908</ul>
909
Daniel Veillard6388e172000-07-03 16:07:19 +0000[diff] [blame]910<h3>2.1.1: July 1 2000</h3>
911<ul>
912 <li>fixes a couple of bugs in the 2.1.0 packaging</li>
913 <li>improvements on the HTML parser</li>
914</ul>
915
Daniel Veillard3f6f7f62000-06-30 17:58:25 +0000[diff] [blame]916<h3>2.1.0 and 1.8.8: June 29 2000</h3>
917<ul>
918 <li>1.8.8 is mostly a comodity package for upgrading to libxml2 accoding to
919 <a href="upgrade.html">new instructions</a>. It fixes a nasty problem
920 about &amp;#38; charref parsing</li>
921 <li>2.1.0 also ease the upgrade from libxml v1 to the recent version. it
922 also contains numerous fixes and enhancements:
923 <ul>
924 <li>added xmlStopParser() to stop parsing</li>
925 <li>improved a lot parsing speed when there is large CDATA blocs</li>
926 <li>includes XPath patches provided by Picdar Technology</li>
927 <li>tried to fix as much as possible DtD validation and namespace
928 related problems</li>
929 <li>output to a given encoding has been added/tested</li>
930 <li>lot of various fixes</li>
931 </ul>
932 </li>
933</ul>
934
Daniel Veillarde0aed302000-04-16 08:52:20 +0000[diff] [blame]935<h3>2.0.0: Apr 12 2000</h3>
Daniel Veillard361d8452000-04-03 19:48:13 +0000[diff] [blame]936<ul>
937 <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]938 idea to check the 1.x to 2.x upgrade instructions. NOTE: while initally
939 scheduled for Apr 3 the relase occured only on Apr 12 due to massive
940 workload.</li>
Daniel Veillard361d8452000-04-03 19:48:13 +0000[diff] [blame]941 <li>The include are now located under $prefix/include/libxml (instead of
Daniel Veillarde0aed302000-04-16 08:52:20 +0000[diff] [blame]942 $prefix/include/gnome-xml), they also are referenced by
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]943 <pre>#include &lt;libxml/xxx.h&gt;</pre>
Daniel Veillarde0aed302000-04-16 08:52:20 +0000[diff] [blame]944 <p>instead of</p>
Daniel Veillard361d8452000-04-03 19:48:13 +0000[diff] [blame]945 <pre>#include "xxx.h"</pre>
946 </li>
Daniel Veillard8f621982000-03-20 13:07:15 +0000[diff] [blame]947 <li>a new URI module for parsing URIs and following strictly RFC 2396</li>
948 <li>the memory allocation routines used by libxml can now be overloaded
949 dynamically by using xmlMemSetup()</li>
Daniel Veillard361d8452000-04-03 19:48:13 +0000[diff] [blame]950 <li>The previously CVS only tool tester has been renamed
951 <strong>xmllint</strong> and is now installed as part of the libxml2
952 package</li>
Daniel Veillarde0aed302000-04-16 08:52:20 +0000[diff] [blame]953 <li>The I/O interface has been revamped. There is now ways to plug in
954 specific I/O modules, either at the URI scheme detection level using
955 xmlRegisterInputCallbacks() or by passing I/O functions when creating a
956 parser context using xmlCreateIOParserCtxt()</li>
957 <li>there is a C preprocessor macro LIBXML_VERSION providing the version
958 number of the libxml module in use</li>
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]959 <li>a number of optional features of libxml can now be excluded at
960 configure time (FTP/HTTP/HTML/XPath/Debug)</li>
Daniel Veillardedfb29b2000-03-14 19:59:05 +0000[diff] [blame]961</ul>
962
963<h3>2.0.0beta: Mar 14 2000</h3>
964<ul>
965 <li>This is a first Beta release of libxml version 2</li>
Daniel Veillarde356c282001-03-10 12:32:04 +0000[diff] [blame]966 <li>It's available only from<a href="ftp://xmlsoft.org/">xmlsoft.org
967 FTP</a>, it's packaged as libxml2-2.0.0beta and available as tar and
968 RPMs</li>
Daniel Veillardedfb29b2000-03-14 19:59:05 +0000[diff] [blame]969 <li>This version is now the head in the Gnome CVS base, the old one is
970 available under the tag LIB_XML_1_X</li>
971 <li>This includes a very large set of changes. Froma programmatic point of
972 view applications should not have to be modified too much, check the <a
973 href="upgrade.html">upgrade page</a></li>
974 <li>Some interfaces may changes (especially a bit about encoding).</li>
975 <li>the updates includes:
Daniel Veillard6c8b1172000-03-01 00:40:41 +0000[diff] [blame]976 <ul>
Daniel Veillardedfb29b2000-03-14 19:59:05 +0000[diff] [blame]977 <li>fix I18N support. ISO-Latin-x/UTF-8/UTF-16 (nearly) seems correctly
978 handled now</li>
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]979 <li>Better handling of entities, especially well formedness checking
980 and proper PEref extensions in external subsets</li>
Daniel Veillard6c8b1172000-03-01 00:40:41 +0000[diff] [blame]981 <li>DTD conditional sections</li>
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]982 <li>Validation now correcly handle entities content</li>
Daniel Veillard6c8b1172000-03-01 00:40:41 +0000[diff] [blame]983 <li><a href="http://rpmfind.net/tools/gdome/messages/0039.html">change
984 structures to accomodate DOM</a></li>
Daniel Veillard6c8b1172000-03-01 00:40:41 +0000[diff] [blame]985 </ul>
986 </li>
Daniel Veillardedfb29b2000-03-14 19:59:05 +0000[diff] [blame]987 <li>Serious progress were made toward compliance, <a
988 href="conf/result.html">here are the result of the test</a> against the
989 OASIS testsuite (except the japanese tests since I don't support that
990 encoding yet). This URL is rebuilt every couple of hours using the CVS
991 head version.</li>
Daniel Veillarde41f2b72000-01-30 20:00:07 +0000[diff] [blame]992</ul>
993
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]994<h3>1.8.7: Mar 6 2000</h3>
995<ul>
996 <li>This is a bug fix release:</li>
997 <li>It is possible to disable the ignorable blanks heuristic used by
998 libxml-1.x, a new function xmlKeepBlanksDefault(0) will allow this. Note
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]999 that for adherence to XML spec, this behaviour will be disabled by
1000 default in 2.x . The same function will allow to keep compatibility for
1001 old code.</li>
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]1002 <li>Blanks in &lt;a&gt; &lt;/a&gt; constructs are not ignored anymore,
1003 avoiding heuristic is really the Right Way :-\</li>
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]1004 <li>The unchecked use of snprintf which was breaking libxml-1.8.6
1005 compilation on some platforms has been fixed</li>
1006 <li>nanoftp.c nanohttp.c: Fixed '#' and '?' stripping when processing
1007 URIs</li>
1008</ul>
1009
Daniel Veillarde41f2b72000-01-30 20:00:07 +0000[diff] [blame]1010<h3>1.8.6: Jan 31 2000</h3>
1011<ul>
1012 <li>added a nanoFTP transport module, debugged until the new version of <a
1013 href="http://rpmfind.net/linux/rpm2html/rpmfind.html">rpmfind</a> can use
1014 it without troubles</li>
Daniel Veillardda07c342000-01-25 18:31:22 +0000[diff] [blame]1015</ul>
1016
1017<h3>1.8.5: Jan 21 2000</h3>
1018<ul>
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]1019 <li>adding APIs to parse a well balanced chunk of XML (production <a
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]1020 href="http://www.w3.org/TR/REC-xml#NT-content">[43] content</a> of the
1021 XML spec)</li>
Daniel Veillard461a66c2000-01-18 18:01:01 +0000[diff] [blame]1022 <li>fixed a hideous bug in xmlGetProp pointed by Rune.Djurhuus@fast.no</li>
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]1023 <li>Jody Goldberg &lt;jgoldberg@home.com&gt; provided another patch trying
1024 to solve the zlib checks problems</li>
Daniel Veillard461a66c2000-01-18 18:01:01 +0000[diff] [blame]1025 <li>The current state in gnome CVS base is expected to ship as 1.8.5 with
1026 gnumeric soon</li>
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]1027</ul>
1028
1029<h3>1.8.4: Jan 13 2000</h3>
1030<ul>
1031 <li>bug fixes, reintroduced xmlNewGlobalNs(), fixed xmlNewNs()</li>
1032 <li>all exit() call should have been removed from libxml</li>
1033 <li>fixed a problem with INCLUDE_WINSOCK on WIN32 platform</li>
1034 <li>added newDocFragment()</li>
Daniel Veillardf84f71f2000-01-05 19:54:23 +0000[diff] [blame]1035</ul>
1036
1037<h3>1.8.3: Jan 5 2000</h3>
1038<ul>
1039 <li>a Push interface for the XML and HTML parsers</li>
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]1040 <li>a shell-like interface to the document tree (try tester --shell :-)</li>
Daniel Veillarddbfd6411999-12-28 16:35:14 +0000[diff] [blame]1041 <li>lots of bug fixes and improvement added over XMas hollidays</li>
Daniel Veillard437b87b2000-01-03 17:30:46 +0000[diff] [blame]1042 <li>fixed the DTD parsing code to work with the xhtml DTD</li>
Daniel Veillardf84f71f2000-01-05 19:54:23 +0000[diff] [blame]1043 <li>added xmlRemoveProp(), xmlRemoveID() and xmlRemoveRef()</li>
1044 <li>Fixed bugs in xmlNewNs()</li>
Daniel Veillard437b87b2000-01-03 17:30:46 +0000[diff] [blame]1045 <li>External entity loading code has been revamped, now it uses
Daniel Veillardf84f71f2000-01-05 19:54:23 +0000[diff] [blame]1046 xmlLoadExternalEntity(), some fix on entities processing were added</li>
Daniel Veillard437b87b2000-01-03 17:30:46 +0000[diff] [blame]1047 <li>cleaned up WIN32 includes of socket stuff</li>
Daniel Veillard5cb5ab81999-12-21 15:35:29 +0000[diff] [blame]1048</ul>
1049
1050<h3>1.8.2: Dec 21 1999</h3>
1051<ul>
Daniel Veillardb24054a1999-12-18 15:32:46 +0000[diff] [blame]1052 <li>I got another problem with includes and C++, I hope this issue is fixed
1053 for good this time</li>
Daniel Veillard5cb5ab81999-12-21 15:35:29 +0000[diff] [blame]1054 <li>Added a few tree modification functions: xmlReplaceNode,
1055 xmlAddPrevSibling, xmlAddNextSibling, xmlNodeSetName and
1056 xmlDocSetRootElement</li>
1057 <li>Tried to improve the HTML output with help from <a
1058 href="mailto:clahey@umich.edu">Chris Lahey</a></li>
Daniel Veillarde4e51311999-12-18 15:32:46 +0000[diff] [blame]1059</ul>
Daniel Veillardb24054a1999-12-18 15:32:46 +0000[diff] [blame]1060
Daniel Veillarde4e51311999-12-18 15:32:46 +0000[diff] [blame]1061<h3>1.8.1: Dec 18 1999</h3>
1062<ul>
1063 <li>various patches to avoid troubles when using libxml with C++ compilers
1064 the "namespace" keyword and C escaping in include files</li>
1065 <li>a problem in one of the core macros IS_CHAR was corrected</li>
1066 <li>fixed a bug introduced in 1.8.0 breaking default namespace processing,
1067 and more specifically the Dia application</li>
Daniel Veillard944b5ff1999-12-15 19:08:24 +0000[diff] [blame]1068 <li>fixed a posteriori validation (validation after parsing, or by using a
1069 Dtd not specified in the original document)</li>
Daniel Veillardb24054a1999-12-18 15:32:46 +0000[diff] [blame]1070 <li>fixed a bug in</li>
Daniel Veillard10a2c651999-12-12 13:03:50 +0000[diff] [blame]1071</ul>
1072
1073<h3>1.8.0: Dec 12 1999</h3>
1074<ul>
1075 <li>cleanup, especially memory wise</li>
1076 <li>the parser should be more reliable, especially the HTML one, it should
1077 not crash, whatever the input !</li>
1078 <li>Integrated various patches, especially a speedup improvement for large
1079 dataset from <a href="mailto:cnygard@bellatlantic.net">Carl Nygard</a>,
1080 configure with --with-buffers to enable them.</li>
1081 <li>attribute normalization, oops should have been added long ago !</li>
1082 <li>attributes defaulted from Dtds should be available, xmlSetProp() now
1083 does entities escapting by default.</li>
Daniel Veillard4c3a2031999-11-19 17:46:26 +0000[diff] [blame]1084</ul>
Daniel Veillard35008381999-10-25 13:15:52 +0000[diff] [blame]1085
1086<h3>1.7.4: Oct 25 1999</h3>
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]1087<ul>
Daniel Veillard35008381999-10-25 13:15:52 +0000[diff] [blame]1088 <li>Lots of HTML improvement</li>
1089 <li>Fixed some errors when saving both XML and HTML</li>
1090 <li>More examples, the regression tests should now look clean</li>
1091 <li>Fixed a bug with contiguous charref</li>
1092</ul>
1093
1094<h3>1.7.3: Sep 29 1999</h3>
1095<ul>
1096 <li>portability problems fixed</li>
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]1097 <li>snprintf was used unconditionnally, leading to link problems on system
Daniel Veillard35008381999-10-25 13:15:52 +0000[diff] [blame]1098 were it's not available, fixed</li>
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]1099</ul>
1100
1101<h3>1.7.1: Sep 24 1999</h3>
1102<ul>
1103 <li>The basic type for strings manipulated by libxml has been renamed in
1104 1.7.1 from <strong>CHAR</strong> to <strong>xmlChar</strong>. The reason
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]1105 is that CHAR was conflicting with a predefined type on Windows. However
1106 on non WIN32 environment, compatibility is provided by the way of a
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]1107 <strong>#define </strong>.</li>
1108 <li>Changed another error : the use of a structure field called errno, and
1109 leading to troubles on platforms where it's a macro</li>
1110</ul>
1111
1112<h3>1.7.0: sep 23 1999</h3>
1113<ul>
1114 <li>Added the ability to fetch remote DTD or parsed entities, see the <a
Daniel Veillard9cb5ff42001-01-29 08:22:21 +0000[diff] [blame]1115 href="html/libxml-nanohttp.html">nanohttp</a> module.</li>
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]1116 <li>Added an errno to report errors by another mean than a simple printf
1117 like callback</li>
1118 <li>Finished ID/IDREF support and checking when validation</li>
1119 <li>Serious memory leaks fixed (there is now a <a
Daniel Veillard9cb5ff42001-01-29 08:22:21 +0000[diff] [blame]1120 href="html/libxml-xmlmemory.html">memory wrapper</a> module)</li>
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]1121 <li>Improvement of <a href="http://www.w3.org/TR/xpath">XPath</a>
1122 implementation</li>
1123 <li>Added an HTML parser front-end</li>
1124</ul>
1125
1126<h2><a name="XML">XML</a></h2>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]1127
Daniel Veillard402e8c82000-02-29 22:57:47 +0000[diff] [blame]1128<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]1129markup-based structured documents. Here is <a name="example">an example XML
1130document</a>:</p>
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]1131<pre>&lt;?xml version="1.0"?&gt;
1132&lt;EXAMPLE prop1="gnome is great" prop2="&amp;amp; linux too"&gt;
1133 &lt;head&gt;
1134 &lt;title&gt;Welcome to Gnome&lt;/title&gt;
1135 &lt;/head&gt;
1136 &lt;chapter&gt;
1137 &lt;title&gt;The Linux adventure&lt;/title&gt;
1138 &lt;p&gt;bla bla bla ...&lt;/p&gt;
1139 &lt;image href="linus.gif"/&gt;
1140 &lt;p&gt;...&lt;/p&gt;
1141 &lt;/chapter&gt;
1142&lt;/EXAMPLE&gt;</pre>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]1143
Daniel Veillard402e8c82000-02-29 22:57:47 +0000[diff] [blame]1144<p>The first line specifies that it's an XML document and gives useful
1145information about its encoding. Then the document is a text format whose
1146structure is specified by tags between brackets. <strong>Each tag opened has
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]1147to be closed</strong>. XML is pedantic about this. However, if a tag is empty
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]1148(no content), a single tag can serve as both the opening and closing tag if
1149it ends with <code>/&gt;</code> rather than with <code>&gt;</code>. Note
1150that, for example, the image tag has no content (just an attribute) and is
1151closed by ending the tag with <code>/&gt;</code>.</p>
Daniel Veillardccb09631998-10-27 06:21:04 +0000[diff] [blame]1152
Daniel Veillard402e8c82000-02-29 22:57:47 +0000[diff] [blame]1153<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]1154structured document maintenance (where it follows the steps of SGML) to
1155simple data encoding mechanisms like configuration file formatting (glade),
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]1156spreadsheets (gnumeric), or even shorter lived documents such as WebDAV where
1157it is used to encode remote calls between a client and a server.</p>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]1158
Daniel Veillard82687162001-01-22 15:32:01 +0000[diff] [blame]1159<h2><a name="XSLT">XSLT</a></h2>
1160
Daniel Veillard6e6a6cc2001-02-15 15:55:44 +0000[diff] [blame]1161<p>Check <a href="http://xmlsoft.org/XSLT">the separate libxslt page</a></p>
1162
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]1163<p><a href="http://www.w3.org/TR/xslt">XSL Transformations</a>, is a
1164language for transforming XML documents into other XML documents (or
1165HTML/textual output).</p>
Daniel Veillard82687162001-01-22 15:32:01 +0000[diff] [blame]1166
1167<p>A separate library called libxslt is being built on top of libxml2. This
1168module "libxslt" can be found in the Gnome CVS base too.</p>
1169
Daniel Veillard383b1472001-01-23 11:39:52 +0000[diff] [blame]1170<p>You can check the <a
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]1171href="http://cvs.gnome.org/lxr/source/libxslt/FEATURES">features</a>
1172supported and the progresses on the <a
Daniel Veillard82687162001-01-22 15:32:01 +0000[diff] [blame]1173href="http://cvs.gnome.org/lxr/source/libxslt/ChangeLog">Changelog</a></p>
1174
Daniel Veillardb8cfbd12001-10-25 10:53:28 +0000[diff] [blame^]1175<h2><a name="architecture">libxml architecture</a></h2>
Daniel Veillard4540be42000-08-19 16:40:28 +0000[diff] [blame]1176
Daniel Veillardec70e912001-02-26 20:10:45 +0000[diff] [blame]1177<p>Libxml is made of multiple components; some of them are optional, and most
1178of the block interfaces are public. The main components are:</p>
Daniel Veillard4540be42000-08-19 16:40:28 +0000[diff] [blame]1179<ul>
1180 <li>an Input/Output layer</li>
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]1181 <li>FTP and HTTP client layers (optional)</li>
Daniel Veillard4540be42000-08-19 16:40:28 +0000[diff] [blame]1182 <li>an Internationalization layer managing the encodings support</li>
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]1183 <li>a URI module</li>
Daniel Veillard4540be42000-08-19 16:40:28 +0000[diff] [blame]1184 <li>the XML parser and its basic SAX interface</li>
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]1185 <li>an HTML parser using the same SAX interface (optional)</li>
Daniel Veillard4540be42000-08-19 16:40:28 +0000[diff] [blame]1186 <li>a SAX tree module to build an in-memory DOM representation</li>
1187 <li>a tree module to manipulate the DOM representation</li>
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]1188 <li>a validation module using the DOM representation (optional)</li>
Daniel Veillard4540be42000-08-19 16:40:28 +0000[diff] [blame]1189 <li>an XPath module for global lookup in a DOM representation
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]1190 (optional)</li>
1191 <li>a debug module (optional)</li>
Daniel Veillard4540be42000-08-19 16:40:28 +0000[diff] [blame]1192</ul>
1193
1194<p>Graphically this gives the following:</p>
1195
1196<p><img src="libxml.gif" alt="a graphical view of the various"></p>
1197
1198<p></p>
1199
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]1200<h2><a name="tree">The tree output</a></h2>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]1201
1202<p>The parser returns a tree built during the document analysis. The value
Daniel Veillard402e8c82000-02-29 22:57:47 +0000[diff] [blame]1203returned is an <strong>xmlDocPtr</strong> (i.e., a pointer to an
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]1204<strong>xmlDoc</strong> structure). This structure contains information such
Daniel Veillard306be992000-07-03 12:38:45 +0000[diff] [blame]1205as the file name, the document type, and a <strong>children</strong> pointer
1206which is the root of the document (or more exactly the first child under the
1207root which is the document). The tree is made of <strong>xmlNode</strong>s,
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]1208chained in double-linked lists of siblings and with a children&lt;-&gt;parent
Daniel Veillard306be992000-07-03 12:38:45 +0000[diff] [blame]1209relationship. An xmlNode can also carry properties (a chain of xmlAttr
1210structures). An attribute may have a value which is a list of TEXT or
1211ENTITY_REF nodes.</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]1212
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]1213<p>Here is an example (erroneous with respect to the XML spec since there
1214should be only one ELEMENT under the root):</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]1215
1216<p><img src="structure.gif" alt=" structure.gif "></p>
1217
1218<p>In the source package there is a small program (not installed by default)
Daniel Veillard361d8452000-04-03 19:48:13 +0000[diff] [blame]1219called <strong>xmllint</strong> which parses XML files given as argument and
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]1220prints them back as parsed. This is useful for detecting errors both in XML
1221code and in the XML parser itself. It has an option <strong>--debug</strong>
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]1222which prints the actual in-memory structure of the document; here is the
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]1223result with the <a href="#example">example</a> given before:</p>
Daniel Veillard10c6a8f1998-10-28 01:00:12 +0000[diff] [blame]1224<pre>DOCUMENT
1225version=1.0
1226standalone=true
1227 ELEMENT EXAMPLE
1228 ATTRIBUTE prop1
1229 TEXT
1230 content=gnome is great
1231 ATTRIBUTE prop2
1232 ENTITY_REF
1233 TEXT
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]1234 content= linux too
Daniel Veillard402e8c82000-02-29 22:57:47 +0000[diff] [blame]1235 ELEMENT head
Daniel Veillard10c6a8f1998-10-28 01:00:12 +0000[diff] [blame]1236 ELEMENT title
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]1237 TEXT
1238 content=Welcome to Gnome
Daniel Veillard10c6a8f1998-10-28 01:00:12 +0000[diff] [blame]1239 ELEMENT chapter
1240 ELEMENT title
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]1241 TEXT
1242 content=The Linux adventure
Daniel Veillard10c6a8f1998-10-28 01:00:12 +0000[diff] [blame]1243 ELEMENT p
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]1244 TEXT
1245 content=bla bla bla ...
Daniel Veillard10c6a8f1998-10-28 01:00:12 +0000[diff] [blame]1246 ELEMENT image
1247 ATTRIBUTE href
1248 TEXT
1249 content=linus.gif
1250 ELEMENT p
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]1251 TEXT
1252 content=...</pre>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]1253
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]1254<p>This should be useful for learning the internal representation model.</p>
Daniel Veillardccb09631998-10-27 06:21:04 +0000[diff] [blame]1255
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]1256<h2><a name="interface">The SAX interface</a></h2>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]1257
Daniel Veillard402e8c82000-02-29 22:57:47 +0000[diff] [blame]1258<p>Sometimes the DOM tree output is just too large to fit reasonably into
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]1259memory. 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]1260loaded using libxml), it's better to use the SAX interface of libxml. SAX is
1261a <strong>callback-based interface</strong> to the parser. Before parsing,
1262the application layer registers a customized set of callbacks which are
1263called by the library as it progresses through the XML input.</p>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]1264
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]1265<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]1266libxml, see the <a
1267href="http://www.daa.com.au/~james/gnome/xml-sax/xml-sax.html">nice
1268documentation</a>.written by <a href="mailto:james@daa.com.au">James
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]1269Henstridge</a>.</p>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]1270
1271<p>You can debug the SAX behaviour by using the <strong>testSAX</strong>
1272program located in the gnome-xml module (it's usually not shipped in the
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]1273binary packages of libxml, but you can find it in the tar source
Daniel Veillard402e8c82000-02-29 22:57:47 +0000[diff] [blame]1274distribution). Here is the sequence of callbacks that would be reported by
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]1275testSAX when parsing the example XML document shown earlier:</p>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]1276<pre>SAX.setDocumentLocator()
1277SAX.startDocument()
1278SAX.getEntity(amp)
1279SAX.startElement(EXAMPLE, prop1='gnome is great', prop2='&amp;amp; linux too')
1280SAX.characters( , 3)
1281SAX.startElement(head)
1282SAX.characters( , 4)
1283SAX.startElement(title)
1284SAX.characters(Welcome to Gnome, 16)
1285SAX.endElement(title)
1286SAX.characters( , 3)
1287SAX.endElement(head)
1288SAX.characters( , 3)
1289SAX.startElement(chapter)
1290SAX.characters( , 4)
1291SAX.startElement(title)
1292SAX.characters(The Linux adventure, 19)
1293SAX.endElement(title)
1294SAX.characters( , 4)
1295SAX.startElement(p)
1296SAX.characters(bla bla bla ..., 15)
1297SAX.endElement(p)
1298SAX.characters( , 4)
1299SAX.startElement(image, href='linus.gif')
1300SAX.endElement(image)
1301SAX.characters( , 4)
1302SAX.startElement(p)
1303SAX.characters(..., 3)
1304SAX.endElement(p)
1305SAX.characters( , 3)
1306SAX.endElement(chapter)
1307SAX.characters( , 1)
1308SAX.endElement(EXAMPLE)
1309SAX.endDocument()</pre>
1310
Daniel Veillardec70e912001-02-26 20:10:45 +0000[diff] [blame]1311<p>Most of the other interfaces of libxml are based on the DOM tree-building
1312facility, so nearly everything up to the end of this document presupposes the
1313use of the standard DOM tree build. Note that the DOM tree itself is built by
1314a set of registered default callbacks, without internal specific
1315interface.</p>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]1316
Daniel Veillardb8cfbd12001-10-25 10:53:28 +0000[diff] [blame^]1317<h2><a name="Validation">Validation &amp; DTDs</a></h2>
1318
1319<p>Table of Content:</p>
1320<ol>
1321 <li><a href="#General5">General overview</a></li>
1322 <li><a href="#definition">The definition</a></li>
1323 <li><a href="#Simple">Simple rules</a>
1324 <ol>
1325 <li><a href="#reference">How to reference a DTD from a
1326 document</a></li>
1327 <li><a href="#Declaring">Declaring elements</a></li>
1328 <li><a href="#Declaring1">Declaring attributes</a></li>
1329 </ol>
1330 </li>
1331 <li><a href="#Some">Some examples</a></li>
1332 <li><a href="#validate">How to validate</a></li>
1333 <li><a href="#Other">Other resources</a></li>
1334</ol>
1335
1336<h3><a name="General5">General overview</a></h3>
1337
1338<p>Well what is validation and what is a DTD ?</p>
1339
1340<p>DTD is the acronym for Document Type Definition. This is a description of
1341the content for a familly of XML files. This is part of the XML 1.0
1342specification, and alows to describe and check that a given document instance
1343conforms to a set of rules detailing its structure and content.</p>
1344
1345<p>Validation is the process of checking a document against a DTD (more
1346generally against a set of construction rules).</p>
1347
1348<p>The validation process and building DTDs are the two most difficult parts
1349of the XML life cycle. Briefly a DTD defines all the possibles element to be
1350found within your document, what is the formal shape of your document tree
1351(by defining the allowed content of an element, either text, a regular
1352expression for the allowed list of children, or mixed content i.e. both text
1353and children). The DTD also defines the allowed attributes for all elements
1354and the types of the attributes.</p>
1355
1356<h3><a name="definition1">The definition</a></h3>
1357
1358<p>The <a href="http://www.w3.org/TR/REC-xml">W3C XML Recommendation</a> (<a
1359href="http://www.xml.com/axml/axml.html">Tim Bray's annotated version of
1360Rev1</a>):</p>
1361<ul>
1362 <li><a href="http://www.w3.org/TR/REC-xml#elemdecls">Declaring
1363 elements</a></li>
1364 <li><a href="http://www.w3.org/TR/REC-xml#attdecls">Declaring
1365 attributes</a></li>
1366</ul>
1367
1368<p>(unfortunately) all this is inherited from the SGML world, the syntax is
1369ancient...</p>
1370
1371<h3><a name="Simple1">Simple rules</a></h3>
1372
1373<p>Writing DTD can be done in multiple ways, the rules to build them if you
1374need something fixed or something which can evolve over time can be radically
1375different. Really complex DTD like Docbook ones are flexible but quite harder
1376to design. I will just focuse on DTDs for a formats with a fixed simple
1377structure. It is just a set of basic rules, and definitely not exhaustive nor
1378useable for complex DTD design.</p>
1379
1380<h4><a name="reference1">How to reference a DTD from a document</a>:</h4>
1381
1382<p>Assuming the top element of the document is <code>spec</code> and the dtd
1383is placed in the file <code>mydtd</code> in the subdirectory
1384<code>dtds</code> of the directory from where the document were loaded:</p>
1385
1386<p><code>&lt;!DOCTYPE spec SYSTEM "dtds/mydtd"&gt;</code></p>
1387
1388<p>Notes:</p>
1389<ul>
1390 <li>the system string is actually an URI-Reference (as defined in <a
1391 href="http://www.ietf.org/rfc/rfc2396.txt">RFC 2396</a>) so you can use a
1392 full URL string indicating the location of your DTD on the Web, this is a
1393 really good thing to do if you want others to validate your document</li>
1394 <li>it is also possible to associate a <code>PUBLIC</code> identifier (a
1395 magic string) so that the DTd is looked up in catalogs on the client side
1396 without having to locate it on the web</li>
1397 <li>a dtd contains a set of elements and attributes declarations, but they
1398 don't define what the root of the document should be. This is explicitely
1399 told to the parser/validator as the first element of the
1400 <code>DOCTYPE</code> declaration.</li>
1401</ul>
1402
1403<h4><a name="Declaring2">Declaring elements</a>:</h4>
1404
1405<p>The following declares an element <code>spec</code>:</p>
1406
1407<p><code>&lt;!ELEMENT spec (front, body, back?)&gt;</code></p>
1408
1409<p>it also expresses that the spec element contains one <code>front</code>,
1410one <code>body</code> and one optionnal <code>back</code> children elements
1411in this order. The declaration of one element of the structure and its
1412content are done in a single declaration. Similary the following declares
1413<code>div1</code> elements:</p>
1414
1415<p><code>&lt;!ELEMENT div1 (head, (p | list | note)*, div2*)&gt;</code></p>
1416
1417<p>means div1 contains one <code>head</code> then a series of optional
1418<code>p</code>, <code>list</code>s and <code>note</code>s and then an
1419optional <code>div2</code>. And last but not least an element can contain
1420text:</p>
1421
1422<p><code>&lt;!ELEMENT b (#PCDATA)&gt;</code></p>
1423
1424<p><code>b</code> contains text or being of mixed content (text and elements
1425in no particular order):</p>
1426
1427<p><code>&lt;!ELEMENT p (#PCDATA|a|ul|b|i|em)*&gt;</code></p>
1428
1429<p><code>p </code>can contain text or <code>a</code>, <code>ul</code>,
1430<code>b</code>, <code>i </code>or <code>em</code> elements in no particular
1431order.</p>
1432
1433<h4><a name="Declaring1">Declaring attributes</a>:</h4>
1434
1435<p>again the attributes declaration includes their content definition:</p>
1436
1437<p><code>&lt;!ATTLIST termdef name CDATA #IMPLIED&gt;</code></p>
1438
1439<p>means that the element <code>termdef</code> can have a <code>name</code>
1440attribute containing text (<code>CDATA</code>) and which is optionnal
1441(<code>#IMPLIED</code>). The attribute value can also be defined within a
1442set:</p>
1443
1444<p><code>&lt;!ATTLIST list type (bullets|ordered|glossary)
1445"ordered"&gt;</code></p>
1446
1447<p>means <code>list</code> element have a <code>type</code> attribute with 3
1448allowed values "bullets", "ordered" or "glossary" and which default to
1449"ordered" if the attribute is not explicitely specified.</p>
1450
1451<p>The content type of an attribute can be text (<code>CDATA</code>),
1452anchor/reference/references
1453(<code>ID</code>/<code>IDREF</code>/<code>IDREFS</code>), entity(ies)
1454(<code>ENTITY</code>/<code>ENTITIES</code>) or name(s)
1455(<code>NMTOKEN</code>/<code>NMTOKENS</code>). The following defines that a
1456<code>chapter</code> element can have an optional <code>id</code> attribute
1457of type <code>ID</code>, usable for reference from attribute of type
1458IDREF:</p>
1459
1460<p><code>&lt;!ATTLIST chapter id ID #IMPLIED&gt;</code></p>
1461
1462<p>The last value of an attribute definition can be <code>#REQUIRED
1463</code>meaning that the attribute has to be given, <code>#IMPLIED</code>
1464meaning that it is optional, or the default value (possibly prefixed by
1465<code>#FIXED</code> if it is the only allowed).</p>
1466
1467<p>Notes:</p>
1468<ul>
1469 <li>usually the attributes pertaining to a given element are declared in a
1470 single expression, but it is just a convention adopted by a lot of DTD
1471 writers:
1472 <pre>&lt;!ATTLIST termdef
1473 id ID #REQUIRED
1474 name CDATA #IMPLIED&gt;</pre>
1475 <p>The previous construct defines both <code>id</code> and
1476 <code>name</code> attributes for the element <code>termdef</code></p>
1477 </li>
1478</ul>
1479
1480<h3><a name="Some1">Some examples</a></h3>
1481
1482<p>The directory <code>test/valid/dtds/</code> in the libxml distribution
1483contains some complex DTD examples. The <code>test/valid/dia.xml</code>
1484example shows an XML file where the simple DTD is directly included within
1485the document.</p>
1486
1487<h3><a name="validate1">How to validate</a></h3>
1488
1489<p>The simplest is to use the xmllint program comming with libxml. The
1490<code>--valid</code> option turn on validation of the files given as input,
1491for example the following validates a copy of the first revision of the XML
14921.0 specification:</p>
1493
1494<p><code>xmllint --valid --noout test/valid/REC-xml-19980210.xml</code></p>
1495
1496<p>the -- noout is used to not output the resulting tree.</p>
1497
1498<p>The <code>--dtdvalid dtd</code> allows to validate the document(s) against
1499a given DTD.</p>
1500
1501<p>Libxml exports an API to handle DTDs and validation, check the <a
1502href="http://xmlsoft.org/html/libxml-valid.html">associated
1503description</a>.</p>
1504
1505<h3><a name="Other1">Other resources</a></h3>
1506
1507<p>DTDs are as old as SGML. So there may be a number of examples on-line, I
1508will just list one for now, others pointers welcome:</p>
1509<ul>
1510 <li><a href="http://www.xml101.com:8081/dtd/">XML-101 DTD</a></li>
1511</ul>
1512
1513<p>I suggest looking at the examples found under test/valid/dtd and any of
1514the large number of books available on XML. The dia example in test/valid
1515should be both simple and complete enough to allow you to build your own.</p>
1516
1517<p></p>
1518
1519<h2><a name="Memory">Memory Management</a></h2>
1520
1521<p>Table of Content:</p>
1522<ol>
1523 <li><a href="#General3">General overview</a></li>
1524 <li><a href="#setting">Setting libxml set of memory
1525 routines</a></li>
1526 <li><a href="#cleanup">Cleaning up after parsing</a></li>
1527 <li><a href="#Debugging">Debugging routines</a></li>
1528 <li><a href="#General4">General memory requirements</a></li>
1529</ol>
1530
1531<h3><a name="General3">General overview</a></h3>
1532
1533<p>The module <code><a
1534href="http://xmlsoft.org/html/libxml-xmlmemory.html">xmlmemory.h</a></code>
1535provides the interfaces to the libxml memory system:</p>
1536<ul>
1537 <li>libxml does not use the libc memory allocator directly but xmlFree(),
1538 xmlMalloc() and xmlRealloc()</li>
1539 <li>those routines can be reallocated to a specific set of routine, by
1540 default the libc ones i.e. free(), malloc() and realloc()</li>
1541 <li>the xmlmemory.c module includes a set of debugging routine</li>
1542</ul>
1543
1544<h3><a name="setting">Setting libxml set of memory routines</a></h3>
1545
1546<p>It is sometimes useful to not use the default memory allocator, either for
1547debugging, analysis or to implement a specific behaviour on memory management
1548(like on embedded systems). Two function calls are available to do so:</p>
1549<ul>
1550 <li><a href="http://xmlsoft.org/html/libxml-xmlmemory.html">xmlMemGet ()</a>
1551 which return the current set of functions in use by the parser</li>
1552 <li><a
1553 href="http://xmlsoft.org/html/libxml-xmlmemory.html">xmlMemSetup()</a>
1554 which allow to set up a new set of memory allocation functions</li>
1555</ul>
1556
1557<p>Of course a call to xmlMemSetup() should probably be done before calling
1558any other libxml routines (unless you are sure your allocations routines are
1559compatibles).</p>
1560
1561<h3><a name="cleanup">Cleaning up after parsing</a></h3>
1562
1563<p>Libxml is not stateless, there is a few set of memory structures needing
1564allocation before the parser is fully functionnal (some encoding structures
1565for example). This also mean that once parsing is finished there is a tiny
1566amount of memory (a few hundred bytes) which can be recollected if you don't
1567reuse the parser immediately:</p>
1568<ul>
1569 <li><a href="http://xmlsoft.org/html/libxml-parser.html">xmlCleanupParser
1570 ()</a>
1571 is a centralized routine to free the parsing states. Note that it won't
1572 deallocate any produced tree if any (use the xmlFreeDoc() and related
1573 routines for this).</li>
1574 <li><a href="http://xmlsoft.org/html/libxml-parser.html">xmlInitParser
1575 ()</a>
1576 is the dual routine allowing to preallocate the parsing state which can
1577 be useful for example to avoid initialization reentrancy problems when
1578 using libxml in multithreaded applications</li>
1579</ul>
1580
1581<p>Generally xmlCleanupParser() is safe, if needed the state will be rebuild
1582at the next invocation of parser routines, but be careful of the consequences
1583in multithreaded applications.</p>
1584
1585<h3><a name="Debugging">Debugging routines</a></h3>
1586
1587<p>When configured using --with-mem-debug flag (off by default), libxml uses
1588a set of memory allocation debugging routineskeeping track of all allocated
1589blocks and the location in the code where the routine was called. A couple of
1590other debugging routines allow to dump the memory allocated infos to a file
1591or call a specific routine when a given block number is allocated:</p>
1592<ul>
1593 <li><a
1594 href="http://xmlsoft.org/html/libxml-xmlmemory.html">xmlMallocLoc()</a>
1595 <a
1596 href="http://xmlsoft.org/html/libxml-xmlmemory.html">xmlReallocLoc()</a>
1597 and <a
1598 href="http://xmlsoft.org/html/libxml-xmlmemory.html">xmlMemStrdupLoc()</a>
1599 are the memory debugging replacement allocation routines</li>
1600 <li><a href="http://xmlsoft.org/html/libxml-xmlmemory.html">xmlMemoryDump
1601 ()</a>
1602 dumps all the informations about the allocated memory block lefts in the
1603 <code>.memdump</code> file</li>
1604</ul>
1605
1606<p>When developping libxml memory debug is enabled, the tests programs call
1607xmlMemoryDump () and the "make test" regression tests will check for any
1608memory leak during the full regression test sequence, this helps a lot
1609ensuring that libxml does not leak memory and bullet proof memory
1610allocations use (some libc implementations are known to be far too permissive
1611resulting in major portability problems!).</p>
1612
1613<p>If the .memdump reports a leak, it displays the allocation function and
1614also tries to give some informations about the content and structure of the
1615allocated blocks left. This is sufficient in most cases to find the culprit,
1616but not always. Assuming the allocation problem is reproductible, it is
1617possible to find more easilly:</p>
1618<ol>
1619 <li>write down the block number xxxx not allocated</li>
1620 <li>export the environement variable XML_MEM_BREAKPOINT=xxxx</li>
1621 <li>run the program under a debugger and set a breakpoint on
1622 xmlMallocBreakpoint() a specific function called when this precise block
1623 is allocated</li>
1624 <li>when the breakpoint is reached you can then do a fine analysis of the
1625 allocation an step to see the condition resulting in the missing
1626 deallocation.</li>
1627</ol>
1628
1629<p>I used to use a commercial tool to debug libxml memory problems but after
1630noticing that it was not detecting memory leaks that simple mechanism was
1631used and proved extremely efficient until now.</p>
1632
1633<h3><a name="General4">General memory requirements</a></h3>
1634
1635<p>How much libxml memory require ? It's hard to tell in average it depends
1636of a number of things:</p>
1637<ul>
1638 <li>the parser itself should work in a fixed amout of memory, except for
1639 information maintained about the stacks of names and entities locations.
1640 The I/O and encoding handlers will probably account for a few KBytes.
1641 This is true for both the XML and HTML parser (though the HTML parser
1642 need more state).</li>
1643 <li>If you are generating the DOM tree then memory requirements will grow
1644 nearly lineary with the size of the data. In general for a balanced
1645 textual document the internal memory requirement is about 4 times the
1646 size of the UTF8 serialization of this document (exmple the XML-1.0
1647 recommendation is a bit more of 150KBytes and takes 650KBytes of main
1648 memory when parsed). Validation will add a amount of memory required for
1649 maintaining the external Dtd state which should be linear with the
1650 complexity of the content model defined by the Dtd</li>
1651 <li>If you don't care about the advanced features of libxml like
1652 validation, DOM, XPath or XPointer, but really need to work fixed memory
1653 requirements, then the SAX interface should be used.</li>
1654</ul>
1655
1656<p></p>
1657
1658<h2><a name="Encodings">Encodings support</a></h2>
1659
1660<p>Table of Content:</p>
1661<ol>
1662 <li><a href="encoding.html#What">What does internationalization support
1663 mean ?</a></li>
1664 <li><a href="encoding.html#internal">The internal encoding, how and
1665 why</a></li>
1666 <li><a href="encoding.html#implemente">How is it implemented ?</a></li>
1667 <li><a href="encoding.html#Default">Default supported encodings</a></li>
1668 <li><a href="encoding.html#extend">How to extend the existing
1669 support</a></li>
1670</ol>
1671
1672<h3><a name="What">What does internationalization support mean ?</a></h3>
1673
1674<p>XML was designed from the start to allow the support of any character set
1675by using Unicode. Any conformant XML parser has to support the UTF-8 and
1676UTF-16 default encodings which can both express the full unicode ranges. UTF8
1677is a variable length encoding whose greatest point are to resuse the same
1678emcoding for ASCII and to save space for Western encodings, but it is a bit
1679more complex to handle in practice. UTF-16 use 2 bytes per characters (and
1680sometimes combines two pairs), it makes implementation easier, but looks a
1681bit overkill for Western languages encoding. Moreover the XML specification
1682allows document to be encoded in other encodings at the condition that they
1683are clearly labelled as such. For example the following is a wellformed XML
1684document encoded in ISO-8859 1 and using accentuated letter that we French
1685likes for both markup and content:</p>
1686<pre>&lt;?xml version="1.0" encoding="ISO-8859-1"?&gt;
1687&lt;très&gt;là&lt;/très&gt;</pre>
1688
1689<p>Having internationalization support in libxml means the foolowing:</p>
1690<ul>
1691 <li>the document is properly parsed</li>
1692 <li>informations about it's encoding are saved</li>
1693 <li>it can be modified</li>
1694 <li>it can be saved in its original encoding</li>
1695 <li>it can also be saved in another encoding supported by libxml (for
1696 example straight UTF8 or even an ASCII form)</li>
1697</ul>
1698
1699<p>Another very important point is that the whole libxml API, with the
1700exception of a few routines to read with a specific encoding or save to a
1701specific encoding, is completely agnostic about the original encoding of the
1702document.</p>
1703
1704<p>It should be noted too that the HTML parser embedded in libxml now obbey
1705the same rules too, the following document will be (as of 2.2.2) handled in
1706an internationalized fashion by libxml too:</p>
1707<pre>&lt;!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN"
1708 "http://www.w3.org/TR/REC-html40/loose.dtd"&gt;
1709&lt;html lang="fr"&gt;
1710&lt;head&gt;
1711 &lt;META HTTP-EQUIV="Content-Type" CONTENT="text/html; charset=ISO-8859-1"&gt;
1712&lt;/head&gt;
1713&lt;body&gt;
1714&lt;p&gt;W3C crée des standards pour le Web.&lt;/body&gt;
1715&lt;/html&gt;</pre>
1716
1717<h3><a name="internal">The internal encoding, how and why</a></h3>
1718
1719<p>One of the core decision was to force all documents to be converted to a
1720default internal encoding, and that encoding to be UTF-8, here are the
1721rationale for those choices:</p>
1722<ul>
1723 <li>keeping the native encoding in the internal form would force the libxml
1724 users (or the code associated) to be fully aware of the encoding of the
1725 original document, for examples when adding a text node to a document,
1726 the content would have to be provided in the document encoding, i.e. the
1727 client code would have to check it before hand, make sure it's conformant
1728 to the encoding, etc ... Very hard in practice, though in some specific
1729 cases this may make sense.</li>
1730 <li>the second decision was which encoding. From the XML spec only UTF8 and
1731 UTF16 really makes sense as being the two only encodings for which there
1732 is amndatory support. UCS-4 (32 bits fixed size encoding) could be
1733 considered an intelligent choice too since it's a direct Unicode mapping
1734 support. I selected UTF-8 on the basis of efficiency and compatibility
1735 with surrounding software:
1736 <ul>
1737 <li>UTF-8 while a bit more complex to convert from/to (i.e. slightly
1738 more costly to import and export CPU wise) is also far more compact
1739 than UTF-16 (and UCS-4) for a majority of the documents I see it used
1740 for right now (RPM RDF catalogs, advogato data, various configuration
1741 file formats, etc.) and the key point for today's computer
1742 architecture is efficient uses of caches. If one nearly double the
1743 memory requirement to store the same amount of data, this will trash
1744 caches (main memory/external caches/internal caches) and my take is
1745 that this harms the system far more than the CPU requirements needed
1746 for the conversion to UTF-8</li>
1747 <li>Most of libxml version 1 users were using it with straight ASCII
1748 most of the time, doing the conversion with an internal encoding
1749 requiring all their code to be rewritten was a serious show-stopper
1750 for using UTF-16 or UCS-4.</li>
1751 <li>UTF-8 is being used as the de-facto internal encoding standard for
1752 related code like the <a href="http://www.pango.org/">pango</a>
1753 upcoming Gnome text widget, and a lot of Unix code (yep another place
1754 where Unix programmer base takes a different approach from Microsoft
1755 - they are using UTF-16)</li>
1756 </ul>
1757 </li>
1758</ul>
1759
1760<p>What does this mean in practice for the libxml user:</p>
1761<ul>
1762 <li>xmlChar, the libxml data type is a byte, those bytes must be assembled
1763 as UTF-8 valid strings. The proper way to terminate an xmlChar * string
1764 is simply to append 0 byte, as usual.</li>
1765 <li>One just need to make sure that when using chars outside the ASCII set,
1766 the values has been properly converted to UTF-8</li>
1767</ul>
1768
1769<h3><a name="implemente">How is it implemented ?</a></h3>
1770
1771<p>Let's describe how all this works within libxml, basically the I18N
1772(internationalization) support get triggered only during I/O operation, i.e.
1773when reading a document or saving one. Let's look first at the reading
1774sequence:</p>
1775<ol>
1776 <li>when a document is processed, we usually don't know the encoding, a
1777 simple heuristic allows to detect UTF-18 and UCS-4 from whose where the
1778 ASCII range (0-0x7F) maps with ASCII</li>
1779 <li>the xml declaration if available is parsed, including the encoding
1780 declaration. At that point, if the autodetected encoding is different
1781 from the one declared a call to xmlSwitchEncoding() is issued.</li>
1782 <li>If there is no encoding declaration, then the input has to be in either
1783 UTF-8 or UTF-16, if it is not then at some point when processing the
1784 input, the converter/checker of UTF-8 form will raise an encoding error.
1785 You may end-up with a garbled document, or no document at all ! Example:
1786 <pre>~/XML -&gt; ./xmllint err.xml
1787err.xml:1: error: Input is not proper UTF-8, indicate encoding !
1788&lt;très&gt;là&lt;/très&gt;
1789 ^
1790err.xml:1: error: Bytes: 0xE8 0x73 0x3E 0x6C
1791&lt;très&gt;là&lt;/très&gt;
1792 ^</pre>
1793 </li>
1794 <li>xmlSwitchEncoding() does an encoding name lookup, canonalize it, and
1795 then search the default registered encoding converters for that encoding.
1796 If it's not within the default set and iconv() support has been compiled
1797 it, it will ask iconv for such an encoder. If this fails then the parser
1798 will report an error and stops processing:
1799 <pre>~/XML -&gt; ./xmllint err2.xml
1800err2.xml:1: error: Unsupported encoding UnsupportedEnc
1801&lt;?xml version="1.0" encoding="UnsupportedEnc"?&gt;
1802 ^</pre>
1803 </li>
1804 <li>From that point the encoder process progressingly the input (it is
1805 plugged as a front-end to the I/O module) for that entity. It captures
1806 and convert on-the-fly the document to be parsed to UTF-8. The parser
1807 itself just does UTF-8 checking of this input and process it
1808 transparently. The only difference is that the encoding information has
1809 been added to the parsing context (more precisely to the input
1810 corresponding to this entity).</li>
1811 <li>The result (when using DOM) is an internal form completely in UTF-8
1812 with just an encoding information on the document node.</li>
1813</ol>
1814
1815<p>Ok then what's happen when saving the document (assuming you
1816colllected/built an xmlDoc DOM like structure) ? It depends on the function
1817called, xmlSaveFile() will just try to save in the original encoding, while
1818xmlSaveFileTo() and xmlSaveFileEnc() can optionally save to a given
1819encoding:</p>
1820<ol>
1821 <li>if no encoding is given, libxml will look for an encoding value
1822 associated to the document and if it exists will try to save to that
1823 encoding,
1824 <p>otherwise everything is written in the internal form, i.e. UTF-8</p>
1825 </li>
1826 <li>so if an encoding was specified, either at the API level or on the
1827 document, libxml will again canonalize the encoding name, lookup for a
1828 converter in the registered set or through iconv. If not found the
1829 function will return an error code</li>
1830 <li>the converter is placed before the I/O buffer layer, as another kind of
1831 buffer, then libxml will simply push the UTF-8 serialization to through
1832 that buffer, which will then progressively be converted and pushed onto
1833 the I/O layer.</li>
1834 <li>It is possible that the converter code fails on some input, for example
1835 trying to push an UTF-8 encoded chinese character through the UTF-8 to
1836 ISO-8859-1 converter won't work. Since the encoders are progressive they
1837 will just report the error and the number of bytes converted, at that
1838 point libxml will decode the offending character, remove it from the
1839 buffer and replace it with the associated charRef encoding &amp;#123; and
1840 resume the convertion. This guarante that any document will be saved
1841 without losses (except for markup names where this is not legal, this is
1842 a problem in the current version, in pactice avoid using non-ascci
1843 characters for tags or attributes names @@). A special "ascii" encoding
1844 name is used to save documents to a pure ascii form can be used when
1845 portability is really crucial</li>
1846</ol>
1847
1848<p>Here is a few examples based on the same test document:</p>
1849<pre>~/XML -&gt; ./xmllint isolat1
1850&lt;?xml version="1.0" encoding="ISO-8859-1"?&gt;
1851&lt;très&gt;là&lt;/très&gt;
1852~/XML -&gt; ./xmllint --encode UTF-8 isolat1
1853&lt;?xml version="1.0" encoding="UTF-8"?&gt;
1854&lt;très&gt;là  &lt;/très&gt;
1855~/XML -&gt; </pre>
1856
1857<p>The same processing is applied (and reuse most of the code) for HTML I18N
1858processing. Looking up and modifying the content encoding is a bit more
1859difficult since it is located in a &lt;meta&gt; tag under the &lt;head&gt;,
1860so a couple of functions htmlGetMetaEncoding() and htmlSetMetaEncoding() have
1861been provided. The parser also attempts to switch encoding on the fly when
1862detecting such a tag on input. Except for that the processing is the same
1863(and again reuses the same code).</p>
1864
1865<h3><a name="Default">Default supported encodings</a></h3>
1866
1867<p>libxml has a set of default converters for the following encodings
1868(located in encoding.c):</p>
1869<ol>
1870 <li>UTF-8 is supported by default (null handlers)</li>
1871 <li>UTF-16, both little and big endian</li>
1872 <li>ISO-Latin-1 (ISO-8859-1) covering most western languages</li>
1873 <li>ASCII, useful mostly for saving</li>
1874 <li>HTML, a specific handler for the conversion of UTF-8 to ASCII with HTML
1875 predefined entities like &amp;copy; for the Copyright sign.</li>
1876</ol>
1877
1878<p>More over when compiled on an Unix platfor with iconv support the full set
1879of encodings supported by iconv can be instantly be used by libxml. On a
1880linux machine with glibc-2.1 the list of supported encodings and aliases fill
18813 full pages, and include UCS-4, the full set of ISO-Latin encodings, and the
1882various Japanese ones.</p>
1883
1884<h4>Encoding aliases</h4>
1885
1886<p>From 2.2.3, libxml has support to register encoding names aliases. The
1887goal is to be able to parse document whose encoding is supported but where
1888the name differs (for example from the default set of names accepted by
1889iconv). The following functions allow to register and handle new aliases for
1890existing encodings. Once registered libxml will automatically lookup the
1891aliases when handling a document:</p>
1892<ul>
1893 <li>int xmlAddEncodingAlias(const char *name, const char *alias);</li>
1894 <li>int xmlDelEncodingAlias(const char *alias);</li>
1895 <li>const char * xmlGetEncodingAlias(const char *alias);</li>
1896 <li>void xmlCleanupEncodingAliases(void);</li>
1897</ul>
1898
1899<h3><a name="extend">How to extend the existing support</a></h3>
1900
1901<p>Well adding support for new encoding, or overriding one of the encoders
1902(assuming it is buggy) should not be hard, just write an input and output
1903conversion routines to/from UTF-8, and register them using
1904xmlNewCharEncodingHandler(name, xxxToUTF8, UTF8Toxxx), and they will be
1905called automatically if the parser(s) encounter such an encoding name
1906(register it uppercase, this will help). The description of the encoders,
1907their arguments and expected return values are described in the encoding.h
1908header.</p>
1909
1910<p>A quick note on the topic of subverting the parser to use a different
1911internal encoding than UTF-8, in some case people will absolutely want to
1912keep the internal encoding different, I think it's still possible (but the
1913encoding must be compliant with ASCII on the same subrange) though I didn't
1914tried it. The key is to override the default conversion routines (by
1915registering null encoders/decoders for your charsets), and bypass the UTF-8
1916checking of the parser by setting the parser context charset
1917(ctxt-&gt;charset) to something different than XML_CHAR_ENCODING_UTF8, but
1918there is no guarantee taht this will work. You may also have some troubles
1919saving back.</p>
1920
1921<p>Basically proper I18N support is important, this requires at least
1922libxml-2.0.0, but a lot of features and corrections are really available only
1923starting 2.2.</p>
1924
1925<h2><a name="IO">I/O Interfaces</a></h2>
1926
1927<p>Table of Content:</p>
1928<ol>
1929 <li><a href="#General1">General overview</a></li>
1930 <li><a href="#basic">The basic buffer type</a></li>
1931 <li><a href="#Input">Input I/O handlers</a></li>
1932 <li><a href="#Output">Output I/O handlers</a></li>
1933 <li><a href="#entities">The entities loader</a></li>
1934 <li><a href="#Example2">Example of customized I/O</a></li>
1935</ol>
1936
1937<h3><a name="General1">General overview</a></h3>
1938
1939<p>The module <code><a
1940href="http://xmlsoft.org/html/libxml-xmlio.html">xmlIO.h</a></code> provides
1941the interfaces to the libxml I/O system. This consists of 4 main parts:</p>
1942<ul>
1943 <li>Entities loader, this is a routine which tries to fetch the entities
1944 (files) based on their PUBLIC and SYSTEM identifiers. The default loader
1945 don't look at the public identifier since libxml do not maintain a
1946 catalog. You can redefine you own entity loader by using
1947 <code>xmlGetExternalEntityLoader()</code> and
1948 <code>xmlSetExternalEntityLoader()</code>. <a
1949 href="#entities">Check the example</a>.</li>
1950 <li>Input I/O buffers which are a commodity structure used by the parser(s)
1951 input layer to handle fetching the informations to feed the parser. This
1952 provides buffering and is also a placeholder where the encoding
1953 convertors to UTF8 are piggy-backed.</li>
1954 <li>Output I/O buffers are similar to the Input ones and fulfill similar
1955 task but when generating a serialization from a tree.</li>
1956 <li>A mechanism to register sets of I/O callbacks and associate them with
1957 specific naming schemes like the protocol part of the URIs.
1958 <p>This affect the default I/O operations and allows to use specific I/O
1959 handlers for certain names.</p>
1960 </li>
1961</ul>
1962
1963<p>The general mechanism used when loading http://rpmfind.net/xml.html for
1964example in the HTML parser is the following:</p>
1965<ol>
1966 <li>The default entity loader calls <code>xmlNewInputFromFile()</code> with
1967 the parsing context and the URI string.</li>
1968 <li>the URI string is checked against the existing registered handlers
1969 using their match() callback function, if the HTTP module was compiled
1970 in, it is registered and its match() function will succeeds</li>
1971 <li>the open() function of the handler is called and if successful will
1972 return an I/O Input buffer</li>
1973 <li>the parser will the start reading from this buffer and progressively
1974 fetch information from the resource, calling the read() function of the
1975 handler until the resource is exhausted</li>
1976 <li>if an encoding change is detected it will be installed on the input
1977 buffer, providing buffering and efficient use of the conversion
1978 routines</li>
1979 <li>once the parser has finished, the close() function of the handler is
1980 called once and the Input buffer and associed resources are
1981 deallocated.</li>
1982</ol>
1983
1984<p>The user defined callbacks are checked first to allow overriding of the
1985default libxml I/O routines.</p>
1986
1987<h3><a name="basic">The basic buffer type</a></h3>
1988
1989<p>All the buffer manipulation handling is done using the
1990<code>xmlBuffer</code> type define in <code><a
1991href="http://xmlsoft.org/html/libxml-tree.html">tree.h</a> </code>which is a
1992resizable memory buffer. The buffer allocation strategy can be selected to be
1993either best-fit or use an exponential doubling one (CPU vs. memory use
1994tradeoff). The values are <code>XML_BUFFER_ALLOC_EXACT</code> and
1995<code>XML_BUFFER_ALLOC_DOUBLEIT</code>, and can be set individually or on a
1996system wide basis using <code>xmlBufferSetAllocationScheme()</code>. A number
1997of functions allows to manipulate buffers with names starting with the
1998<code>xmlBuffer...</code> prefix.</p>
1999
2000<h3><a name="Input">Input I/O handlers</a></h3>
2001
2002<p>An Input I/O handler is a simple structure
2003<code>xmlParserInputBuffer</code> containing a context associated to the
2004resource (file descriptor, or pointer to a protocol handler), the read() and
2005close() callbacks to use and an xmlBuffer. And extra xmlBuffer and a charset
2006encoding handler are also present to support charset conversion when
2007needed.</p>
2008
2009<h3><a name="Output">Output I/O handlers</a></h3>
2010
2011<p>An Output handler <code>xmlOutputBuffer</code> is completely similar to an
2012Input one except the callbacks are write() and close().</p>
2013
2014<h3><a name="entities">The entities loader</a></h3>
2015
2016<p>The entity loader resolves requests for new entities and create inputs for
2017the parser. Creating an input from a filename or an URI string is done
2018through the xmlNewInputFromFile() routine. The default entity loader do not
2019handle the PUBLIC identifier associated with an entity (if any). So it just
2020calls xmlNewInputFromFile() with the SYSTEM identifier (which is mandatory in
2021XML).</p>
2022
2023<p>If you want to hook up a catalog mechanism then you simply need to
2024override the default entity loader, here is an example:</p>
2025<pre>#include &lt;libxml/xmlIO.h&gt;
2026
2027xmlExternalEntityLoader defaultLoader = NULL;
2028
2029xmlParserInputPtr
2030xmlMyExternalEntityLoader(const char *URL, const char *ID,
2031 xmlParserCtxtPtr ctxt) {
2032 xmlParserInputPtr ret;
2033 const char *fileID = NULL;
2034 /* lookup for the fileID depending on ID */
2035
2036 ret = xmlNewInputFromFile(ctxt, fileID);
2037 if (ret != NULL)
2038 return(ret);
2039 if (defaultLoader != NULL)
2040 ret = defaultLoader(URL, ID, ctxt);
2041 return(ret);
2042}
2043
2044int main(..) {
2045 ...
2046
2047 /*
2048 * Install our own entity loader
2049 */
2050 defaultLoader = xmlGetExternalEntityLoader();
2051 xmlSetExternalEntityLoader(xmlMyExternalEntityLoader);
2052
2053 ...
2054}</pre>
2055
2056<h3><a name="Example2">Example of customized I/O</a></h3>
2057
2058<p>This example come from <a href="http://xmlsoft.org/messages/0708.html">a
2059real use case</a>, xmlDocDump() closes the FILE * passed by the application
2060and this was a problem. The <a
2061href="http://xmlsoft.org/messages/0711.html">solution</a> was to redefine a
2062new output handler with the closing call deactivated:</p>
2063<ol>
2064 <li>First define a new I/O ouput allocator where the output don't close the
2065 file:
2066 <pre>xmlOutputBufferPtr
2067xmlOutputBufferCreateOwn(FILE *file, xmlCharEncodingHandlerPtr encoder) {
2068    xmlOutputBufferPtr ret;
2069    
2070    if (xmlOutputCallbackInitialized == 0)
2071        xmlRegisterDefaultOutputCallbacks();
2072
2073    if (file == NULL) return(NULL);
2074    ret = xmlAllocOutputBuffer(encoder);
2075    if (ret != NULL) {
2076        ret-&gt;context = file;
2077        ret-&gt;writecallback = xmlFileWrite;
2078        ret-&gt;closecallback = NULL; /* No close callback */
2079    }
2080    return(ret); <br>
2081
2082
2083
2084} </pre>
2085 </li>
2086 <li>And then use it to save the document:
2087 <pre>FILE *f;
2088xmlOutputBufferPtr output;
2089xmlDocPtr doc;
2090int res;
2091
2092f = ...
2093doc = ....
2094
2095output = xmlOutputBufferCreateOwn(f, NULL);
2096res = xmlSaveFileTo(output, doc, NULL);
2097 </pre>
2098 </li>
2099</ol>
2100
2101<h2><a name="Catalog">Catalog support</a></h2>
2102
2103<p>Table of Content:</p>
2104<ol>
2105 <li><a href="General2">General overview</a></li>
2106 <li><a href="#definition">The definition</a></li>
2107 <li><a href="#Simple">Using catalogs</a></li>
2108 <li><a href="#Some">Some examples</a></li>
2109 <li><a href="#reference">How to tune catalog usage</a></li>
2110 <li><a href="#validate">How to debug catalog processing</a></li>
2111 <li><a href="#Declaring">How to create and maintain catalogs</a></li>
2112 <li><a href="#implemento">The implementor corner quick review of the
2113 API</a></li>
2114 <li><a href="#Other">Other resources</a></li>
2115</ol>
2116
2117<h3><a name="General2">General overview</a></h3>
2118
2119<p>What is a catalog? Basically it's a lookup mechanism used when an entity
2120(a file or a remote resource) references another entity. The catalog lookup
2121is inserted between the moment the reference is recognized by the software
2122(XML parser, stylesheet processing, or even images referenced for inclusion
2123in a rendering) and the time where loading that resource is actually
2124started.</p>
2125
2126<p>It is basically used for 3 things:</p>
2127<ul>
2128 <li>mapping from "logical" names, the public identifiers and a more
2129 concrete name usable for download (and URI). For example it can associate
2130 the logical name
2131 <p>"-//OASIS//DTD DocBook XML V4.1.2//EN"</p>
2132 <p>of the DocBook 4.1.2 XML DTD with the actual URL where it can be
2133 downloaded</p>
2134 <p>http://www.oasis-open.org/docbook/xml/4.1.2/docbookx.dtd</p>
2135 </li>
2136 <li>remapping from a given URL to another one, like an HTTP indirection
2137 saying that
2138 <p>"http://www.oasis-open.org/committes/tr.xsl"</p>
2139 <p>should really be looked at</p>
2140 <p>"http://www.oasis-open.org/committes/entity/stylesheets/base/tr.xsl"</p>
2141 </li>
2142 <li>providing a local cache mechanism allowing to load the entities
2143 associated to public identifiers or remote resources, this is a really
2144 important feature for any significant deployment of XML or SGML since it
2145 allows to avoid the aleas and delays associated to fetching remote
2146 resources.</li>
2147</ul>
2148
2149<h3><a name="definition">The definitions</a></h3>
2150
2151<p>Libxml, as of 2.4.3 implements 2 kind of catalogs:</p>
2152<ul>
2153 <li>the older SGML catalogs, the official spec is SGML Open Technical
2154 Resolution TR9401:1997, but is better understood by reading <a
2155 href="http://www.jclark.com/sp/catalog.htm">the SP Catalog page</a> from
2156 James Clark. This is relatively old and not the preferred mode of
2157 operation of libxml.</li>
2158 <li><a href="http://www.oasis-open.org/committees/entity/spec.html">XML
2159 Catalogs</a>
2160 is far more flexible, more recent, uses an XML syntax and should scale
2161 quite better. This is the default option of libxml.</li>
2162</ul>
2163
2164<p></p>
2165
2166<h3><a name="Simple">Using catalog</a></h3>
2167
2168<p>In a normal environment libxml will by default check the presence of a
2169catalog in /etc/xml/catalog, and assuming it has been correctly populated,
2170the processing is completely transparent to the document user. To take a
2171concrete example, suppose you are authoring a DocBook document, this one
2172starts with the following DOCTYPE definition:</p>
2173<pre>&lt;?xml version='1.0'?&gt;
2174&lt;!DOCTYPE book PUBLIC "-//Norman Walsh//DTD DocBk XML V3.1.4//EN"
2175 "http://nwalsh.com/docbook/xml/3.1.4/db3xml.dtd"&gt;</pre>
2176
2177<p>When validating the document with libxml, the catalog will be
2178automatically consulted to lookup the public identifier "-//Norman Walsh//DTD
2179DocBk XML V3.1.4//EN" and the system identifier
2180"http://nwalsh.com/docbook/xml/3.1.4/db3xml.dtd", and if these entities have
2181been installed on your system and the catalogs actually point to them, libxml
2182will fetch them from the local disk.</p>
2183
2184<p style="font-size: 10pt"><strong>Note</strong>: Really don't use this
2185DOCTYPE example it's a really old version, but is fine as an example.</p>
2186
2187<p>Libxml will check the catalog each time that it is requested to load an
2188entity, this includes DTD, external parsed entities, stylesheets, etc ... If
2189your system is correctly configured all the authoring phase and processing
2190should use only local files, even if your document stays portable because it
2191uses the canonical public and system ID, referencing the remote document.</p>
2192
2193<h3><a name="Some">Some examples:</a></h3>
2194
2195<p>Here is a couple of fragments from XML Catalogs used in libxml early
2196regression tests in <code>test/catalogs</code> :</p>
2197<pre>&lt;?xml version="1.0"?&gt;
2198&lt;!DOCTYPE catalog PUBLIC
2199 "-//OASIS//DTD Entity Resolution XML Catalog V1.0//EN"
2200 "http://www.oasis-open.org/committees/entity/release/1.0/catalog.dtd"&gt;
2201&lt;catalog xmlns="urn:oasis:names:tc:entity:xmlns:xml:catalog"&gt;
2202 &lt;public publicId="-//OASIS//DTD DocBook XML V4.1.2//EN"
2203 uri="http://www.oasis-open.org/docbook/xml/4.1.2/docbookx.dtd"/&gt;
2204...</pre>
2205
2206<p>This is the beginning of a catalog for DocBook 4.1.2, XML Catalogs are
2207written in XML, there is a specific namespace for catalog elements
2208"urn:oasis:names:tc:entity:xmlns:xml:catalog". The first entry in this
2209catalog is a <code>public</code> mapping it allows to associate a Public
2210Identifier with an URI.</p>
2211<pre>...
2212 &lt;rewriteSystem systemIdStartString="http://www.oasis-open.org/docbook/"
2213 rewritePrefix="file:///usr/share/xml/docbook/"/&gt;
2214...</pre>
2215
2216<p>A <code>rewriteSystem</code> is a very powerful instruction, it says that
2217any URI starting with a given prefix should be looked at another URI
2218constructed by replacing the prefix with an new one. In effect this acts like
2219a cache system for a full area of the Web. In practice it is extremely useful
2220with a file prefix if you have installed a copy of those resources on your
2221local system.</p>
2222<pre>...
2223&lt;delegatePublic publicIdStartString="-//OASIS//DTD XML Catalog //"
2224 catalog="file:///usr/share/xml/docbook.xml"/&gt;
2225&lt;delegatePublic publicIdStartString="-//OASIS//ENTITIES DocBook XML"
2226 catalog="file:///usr/share/xml/docbook.xml"/&gt;
2227&lt;delegatePublic publicIdStartString="-//OASIS//DTD DocBook XML"
2228 catalog="file:///usr/share/xml/docbook.xml"/&gt;
2229&lt;delegateSystem systemIdStartString="http://www.oasis-open.org/docbook/"
2230 catalog="file:///usr/share/xml/docbook.xml"/&gt;
2231&lt;delegateURI uriStartString="http://www.oasis-open.org/docbook/"
2232 catalog="file:///usr/share/xml/docbook.xml"/&gt;
2233...</pre>
2234
2235<p>Delegation is the core features which allows to build a tree of catalogs,
2236easier to maintain than a single catalog, based on Public Identifier, System
2237Identifier or URI prefixes it instructs the catalog software to look up
2238entries in another resource. This feature allow to build hierarchies of
2239catalogs, the set of entries presented should be sufficient to redirect the
2240resolution of all DocBook references to the specific catalog in
2241<code>/usr/share/xml/docbook.xml</code> this one in turn could delegate all
2242references for DocBook 4.2.1 to a specific catalog installed at the same time
2243as the DocBook resources on the local machine.</p>
2244
2245<h3><a name="reference">How to tune catalog usage:</a></h3>
2246
2247<p>The user can change the default catalog behaviour by redirecting queries
2248to its own set of catalogs, this can be done by setting the
2249<code>XML_CATALOG_FILES</code> environment variable to a list of catalogs, an
2250empty one should deactivate loading the default <code>/etc/xml/catalog</code>
2251default catalog</p>
2252
2253<h3><a name="validate">How to debug catalog processing:</a></h3>
2254
2255<p>Setting up the <code>XML_DEBUG_CATALOG</code> environment variable will
2256make libxml output debugging informations for each catalog operations, for
2257example:</p>
2258<pre>orchis:~/XML -&gt; xmllint --memory --noout test/ent2
2259warning: failed to load external entity "title.xml"
2260orchis:~/XML -&gt; export XML_DEBUG_CATALOG=
2261orchis:~/XML -&gt; xmllint --memory --noout test/ent2
2262Failed to parse catalog /etc/xml/catalog
2263Failed to parse catalog /etc/xml/catalog
2264warning: failed to load external entity "title.xml"
2265Catalogs cleanup
2266orchis:~/XML -&gt; </pre>
2267
2268<p>The test/ent2 references an entity, running the parser from memory makes
2269the base URI unavailable and the the "title.xml" entity cannot be loaded.
2270Setting up the debug environment variable allows to detect that an attempt is
2271made to load the <code>/etc/xml/catalog</code> but since it's not present the
2272resolution fails.</p>
2273
2274<p>But the most advanced way to debug XML catalog processing is to use the
2275<strong>xmlcatalog</strong> command shipped with libxml2, it allows to load
2276catalogs and make resolution queries to see what is going on. This is also
2277used for the regression tests:</p>
2278<pre>orchis:~/XML -&gt; ./xmlcatalog test/catalogs/docbook.xml \
2279 "-//OASIS//DTD DocBook XML V4.1.2//EN"
2280http://www.oasis-open.org/docbook/xml/4.1.2/docbookx.dtd
2281orchis:~/XML -&gt; </pre>
2282
2283<p>For debugging what is going on, adding one -v flags increase the verbosity
2284level to indicate the processing done (adding a second flag also indicate
2285what elements are recognized at parsing):</p>
2286<pre>orchis:~/XML -&gt; ./xmlcatalog -v test/catalogs/docbook.xml \
2287 "-//OASIS//DTD DocBook XML V4.1.2//EN"
2288Parsing catalog test/catalogs/docbook.xml's content
2289Found public match -//OASIS//DTD DocBook XML V4.1.2//EN
2290http://www.oasis-open.org/docbook/xml/4.1.2/docbookx.dtd
2291Catalogs cleanup
2292orchis:~/XML -&gt; </pre>
2293
2294<p>A shell interface is also available to debug and process multiple queries
2295(and for regression tests):</p>
2296<pre>orchis:~/XML -&gt; ./xmlcatalog -shell test/catalogs/docbook.xml \
2297 "-//OASIS//DTD DocBook XML V4.1.2//EN"
2298&gt; help
2299Commands available:
2300public PublicID: make a PUBLIC identifier lookup
2301system SystemID: make a SYSTEM identifier lookup
2302resolve PublicID SystemID: do a full resolver lookup
2303add 'type' 'orig' 'replace' : add an entry
2304del 'values' : remove values
2305dump: print the current catalog state
2306debug: increase the verbosity level
2307quiet: decrease the verbosity level
2308exit: quit the shell
2309&gt; public "-//OASIS//DTD DocBook XML V4.1.2//EN"
2310http://www.oasis-open.org/docbook/xml/4.1.2/docbookx.dtd
2311&gt; quit
2312orchis:~/XML -&gt; </pre>
2313
2314<p>This should be sufficient for most debugging purpose, this was actually
2315used heavily to debug the XML Catalog implementation itself.</p>
2316
2317<h3><a name="Declaring">How to create and maintain</a> catalogs:</h3>
2318
2319<p>Basically XML Catalogs are XML files, you can either use XML tools to
2320manage them or use <strong>xmlcatalog</strong> for this. The basic step is
2321to create a catalog the -create option provide this facility:</p>
2322<pre>orchis:~/XML -&gt; ./xmlcatalog --create tst.xml
2323&lt;?xml version="1.0"?&gt;
2324&lt;!DOCTYPE catalog PUBLIC "-//OASIS//DTD Entity Resolution XML Catalog V1.0//EN"
2325 "http://www.oasis-open.org/committees/entity/release/1.0/catalog.dtd"&gt;
2326&lt;catalog xmlns="urn:oasis:names:tc:entity:xmlns:xml:catalog"/&gt;
2327orchis:~/XML -&gt; </pre>
2328
2329<p>By default xmlcatalog does not overwrite the original catalog and save the
2330result on the standard output, this can be overridden using the -noout
2331option. The <code>-add</code> command allows to add entries in the
2332catalog:</p>
2333<pre>orchis:~/XML -&gt; ./xmlcatalog --noout --create --add "public" \
2334 "-//OASIS//DTD DocBook XML V4.1.2//EN" \
2335 http://www.oasis-open.org/docbook/xml/4.1.2/docbookx.dtd tst.xml
2336orchis:~/XML -&gt; cat tst.xml
2337&lt;?xml version="1.0"?&gt;
2338&lt;!DOCTYPE catalog PUBLIC "-//OASIS//DTD Entity Resolution XML Catalog V1.0//EN" \
2339 "http://www.oasis-open.org/committees/entity/release/1.0/catalog.dtd"&gt;
2340&lt;catalog xmlns="urn:oasis:names:tc:entity:xmlns:xml:catalog"&gt;
2341&lt;public publicId="-//OASIS//DTD DocBook XML V4.1.2//EN"
2342 uri="http://www.oasis-open.org/docbook/xml/4.1.2/docbookx.dtd"/&gt;
2343&lt;/catalog&gt;
2344orchis:~/XML -&gt; </pre>
2345
2346<p>The <code>-add</code> option will always take 3 parameters even if some of
2347the XML Catalog constructs (like nextCatalog) will have only a single
2348argument, just pass a third empty string, it will be ignored.</p>
2349
2350<p>Similarly the <code>-del</code> option remove matching entries from the
2351catalog:</p>
2352<pre>orchis:~/XML -&gt; ./xmlcatalog --del \
2353 "http://www.oasis-open.org/docbook/xml/4.1.2/docbookx.dtd" tst.xml
2354&lt;?xml version="1.0"?&gt;
2355&lt;!DOCTYPE catalog PUBLIC "-//OASIS//DTD Entity Resolution XML Catalog V1.0//EN"
2356 "http://www.oasis-open.org/committees/entity/release/1.0/catalog.dtd"&gt;
2357&lt;catalog xmlns="urn:oasis:names:tc:entity:xmlns:xml:catalog"/&gt;
2358orchis:~/XML -&gt; </pre>
2359
2360<p>The catalog is now empty. Note that the matching of <code>-del</code> is
2361exact and would have worked in a similar fashion with the Public ID
2362string.</p>
2363
2364<p>This is rudimentary but should be sufficient to manage a not too complex
2365catalog tree of resources.</p>
2366
2367<h3><a name="implemento">The implementor corner quick review of the
2368API:</a></h3>
2369
2370<p>First, and like for every other module of libxml, there is an
2371automatically generated <a href="html/libxml-catalog.html">API page for
2372catalog support</a>.</p>
2373
2374<p>The header for the catalog interfaces should be included as:</p>
2375<pre>#include &lt;libxml/catalog.h&gt;</pre>
2376
2377<p>The API is voluntarily kept very simple. First it is not obvious that
2378applications really need access to it since it is the default behaviour of
2379libxml (Note: it is possible to completely override libxml default catalog by
2380using <a href="html/libxml-parser.html">xmlSetExternalEntityLoader</a> to
2381plug an application specific resolver).</p>
2382
2383<p>Basically libxml support 2 catalog lists:</p>
2384<ul>
2385 <li>the default one, global shared by all the application</li>
2386 <li>a per-document catalog, this one is built if the document uses the
2387 <code>oasis-xml-catalog</code> PIs to specify its own catalog list, it is
2388 associated to the parser context and destroyed when the parsing context
2389 is destroyed.</li>
2390</ul>
2391
2392<p>the document one will be used first if it exists.</p>
2393
2394<h4>Initialization routines:</h4>
2395
2396<p>xmlInitializeCatalog(), xmlLoadCatalog() and xmlLoadCatalogs() should be
2397used at startup to initialize the catalog, if the catalog should be
2398initialized with specific values xmlLoadCatalog() or xmlLoadCatalogs()
2399should be called before xmlInitializeCatalog() which would otherwise do a
2400default initialization first.</p>
2401
2402<p>The xmlCatalogAddLocal() call is used by the parser to grow the document
2403own catalog list if needed.</p>
2404
2405<h4>Preferences setup:</h4>
2406
2407<p>The XML Catalog spec requires the possibility to select default
2408preferences between public and system delegation,
2409xmlCatalogSetDefaultPrefer() allows this, xmlCatalogSetDefaults() and
2410xmlCatalogGetDefaults() allow to control if XML Catalogs resolution should
2411be forbidden, allowed for global catalog, for document catalog or both, the
2412default is to allow both.</p>
2413
2414<p>And of course xmlCatalogSetDebug() allows to generate debug messages
2415(through the xmlGenericError() mechanism).</p>
2416
2417<h4>Querying routines:</h4>
2418
2419<p>xmlCatalogResolve(), xmlCatalogResolveSystem(), xmlCatalogResolvePublic()
2420and xmlCatalogResolveURI() are relatively explicit if you read the XML
2421Catalog specification they correspond to section 7 algorithms, they should
2422also work if you have loaded an SGML catalog with a simplified semantic.</p>
2423
2424<p>xmlCatalogLocalResolve() and xmlCatalogLocalResolveURI() are the same but
2425operate on the document catalog list</p>
2426
2427<h4>Cleanup and Miscellaneous:</h4>
2428
2429<p>xmlCatalogCleanup() free-up the global catalog, xmlCatalogFreeLocal() is
2430the per-document equivalent.</p>
2431
2432<p>xmlCatalogAdd() and xmlCatalogRemove() are used to dynamically modify the
2433first catalog in the global list, and xmlCatalogDump() allows to dump a
2434catalog state, those routines are primarily designed for xmlcatalog, I'm not
2435sure that exposing more complex interfaces (like navigation ones) would be
2436really useful.</p>
2437
2438<p>The xmlParseCatalogFile() is a function used to load XML Catalog files,
2439it's similar as xmlParseFile() except it bypass all catalog lookups, it's
2440provided because this functionality may be useful for client tools.</p>
2441
2442<h4>threaded environments:</h4>
2443
2444<p>Since the catalog tree is built progressively, some care has been taken to
2445try to avoid troubles in multithreaded environments. The code is now thread
2446safe assuming that the libxml library has been compiled with threads
2447support.</p>
2448
2449<p></p>
2450
2451<h3><a name="Other">Other resources</a></h3>
2452
2453<p>The XML Catalog specification is relatively recent so there isn't much
2454literature to point at:</p>
2455<ul>
2456 <li>You can find an good rant from Norm Walsh about <a
2457 href="http://www.arbortext.com/Think_Tank/XML_Resources/Issue_Three/issue_three.html">the
2458 need for catalogs</a>, it provides a lot of context informations even if
2459 I don't agree with everything presented.</li>
2460 <li>An <a href="http://home.ccil.org/~cowan/XML/XCatalog.html">old XML
2461 catalog proposal</a> from John Cowan</li>
2462 <li>The <a href="http://www.rddl.org/">Resource Directory Description
2463 Language</a> (RDDL) another catalog system but more oriented toward
2464 providing metadata for XML namespaces.</li>
2465 <li>the page from the OASIS Technical <a
2466 href="http://www.oasis-open.org/committees/entity/">Committee on Entity
2467 Resolution</a> who maintains XML Catalog, you will find pointers to the
2468 specification update, some background and pointers to others tools
2469 providing XML Catalog support</li>
2470 <li>I have uploaded <a href="ftp://xmlsoft.org/test/dbk412catalog.tar.gz">a
2471 mall tarball</a> containing XML Catalogs for DocBook 4.1.2 which seems to
2472 work fine for me</li>
2473 <li>The <a href="http://www.xmlsoft.org/xmlcatalog_man.html">xmlcatalog
2474 manual page</a></li>
2475</ul>
2476
2477<p>If you have suggestions for corrections or additions, simply contact
2478me:</p>
2479
2480<h2><a name="library">The parser interfaces</a></h2>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2481
2482<p>This section is directly intended to help programmers getting bootstrapped
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]2483using the XML library from the C language. It is not intended to be
2484extensive. I hope the automatically generated documents will provide the
2485completeness required, but as a separate set of documents. The interfaces of
2486the XML library are by principle low level, there is nearly zero abstraction.
2487Those interested in a higher level API should <a href="#DOM">look at
2488DOM</a>.</p>
Daniel Veillardccb09631998-10-27 06:21:04 +0000[diff] [blame]2489
Daniel Veillard9cb5ff42001-01-29 08:22:21 +0000[diff] [blame]2490<p>The <a href="html/libxml-parser.html">parser interfaces for XML</a> are
2491separated from the <a href="html/libxml-htmlparser.html">HTML parser
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]2492interfaces</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]2493
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]2494<h3><a name="Invoking">Invoking the parser : the pull method</a></h3>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2495
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]2496<p>Usually, the first thing to do is to read an XML input. The parser accepts
2497documents either from in-memory strings or from files. The functions are
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2498defined in "parser.h":</p>
Daniel Veillard10c6a8f1998-10-28 01:00:12 +0000[diff] [blame]2499<dl>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2500 <dt><code>xmlDocPtr xmlParseMemory(char *buffer, int size);</code></dt>
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]2501 <dd><p>Parse a null-terminated string containing the document.</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2502 </dd>
Daniel Veillard10c6a8f1998-10-28 01:00:12 +0000[diff] [blame]2503</dl>
2504<dl>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2505 <dt><code>xmlDocPtr xmlParseFile(const char *filename);</code></dt>
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]2506 <dd><p>Parse an XML document contained in a (possibly compressed)
2507 file.</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2508 </dd>
Daniel Veillard10c6a8f1998-10-28 01:00:12 +0000[diff] [blame]2509</dl>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2510
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]2511<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]2512failure).</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2513
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]2514<h3 id="Invoking1">Invoking the parser: the push method</h3>
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]2515
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]2516<p>In order for the application to keep the control when the document is
2517being fetched (which is common for GUI based programs) libxml provides a push
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]2518interface, too, as of version 1.8.3. Here are the interface functions:</p>
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]2519<pre>xmlParserCtxtPtr xmlCreatePushParserCtxt(xmlSAXHandlerPtr sax,
2520 void *user_data,
2521 const char *chunk,
2522 int size,
2523 const char *filename);
2524int xmlParseChunk (xmlParserCtxtPtr ctxt,
2525 const char *chunk,
2526 int size,
2527 int terminate);</pre>
2528
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]2529<p>and here is a simple example showing how to use the interface:</p>
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]2530<pre> FILE *f;
2531
2532 f = fopen(filename, "r");
2533 if (f != NULL) {
2534 int res, size = 1024;
2535 char chars[1024];
2536 xmlParserCtxtPtr ctxt;
2537
2538 res = fread(chars, 1, 4, f);
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]2539 if (res &gt; 0) {
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]2540 ctxt = xmlCreatePushParserCtxt(NULL, NULL,
2541 chars, res, filename);
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]2542 while ((res = fread(chars, 1, size, f)) &gt; 0) {
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]2543 xmlParseChunk(ctxt, chars, res, 0);
2544 }
2545 xmlParseChunk(ctxt, chars, 0, 1);
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]2546 doc = ctxt-&gt;myDoc;
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]2547 xmlFreeParserCtxt(ctxt);
2548 }
2549 }</pre>
2550
Daniel Veillardec70e912001-02-26 20:10:45 +0000[diff] [blame]2551<p>The HTML parser embedded into libxml also has a push interface; the
2552functions are just prefixed by "html" rather than "xml".</p>
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]2553
2554<h3 id="Invoking2">Invoking the parser: the SAX interface</h3>
2555
Daniel Veillardec70e912001-02-26 20:10:45 +0000[diff] [blame]2556<p>The tree-building interface makes the parser memory-hungry, first loading
2557the document in memory and then building the tree itself. Reading a document
2558without building the tree is possible using the SAX interfaces (see SAX.h and
2559<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]2560Henstridge's documentation</a>). Note also that the push interface can be
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]2561limited to SAX: just use the two first arguments of
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]2562<code>xmlCreatePushParserCtxt()</code>.</p>
Daniel Veillardccb09631998-10-27 06:21:04 +0000[diff] [blame]2563
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]2564<h3><a name="Building">Building a tree from scratch</a></h3>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2565
2566<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]2567there is a set of functions dedicated to building new elements. (These are
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]2568also described in &lt;libxml/tree.h&gt;.) For example, here is a piece of
2569code that produces the XML document used in the previous examples:</p>
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]2570<pre> #include &lt;libxml/tree.h&gt;
Daniel Veillard361d8452000-04-03 19:48:13 +0000[diff] [blame]2571 xmlDocPtr doc;
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]2572 xmlNodePtr tree, subtree;
2573
2574 doc = xmlNewDoc("1.0");
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]2575 doc-&gt;children = xmlNewDocNode(doc, NULL, "EXAMPLE", NULL);
2576 xmlSetProp(doc-&gt;children, "prop1", "gnome is great");
2577 xmlSetProp(doc-&gt;children, "prop2", "&amp; linux too");
2578 tree = xmlNewChild(doc-&gt;children, NULL, "head", NULL);
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]2579 subtree = xmlNewChild(tree, NULL, "title", "Welcome to Gnome");
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]2580 tree = xmlNewChild(doc-&gt;children, NULL, "chapter", NULL);
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]2581 subtree = xmlNewChild(tree, NULL, "title", "The Linux adventure");
2582 subtree = xmlNewChild(tree, NULL, "p", "bla bla bla ...");
2583 subtree = xmlNewChild(tree, NULL, "image", NULL);
2584 xmlSetProp(subtree, "href", "linus.gif");</pre>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2585
2586<p>Not really rocket science ...</p>
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]2587
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]2588<h3><a name="Traversing">Traversing the tree</a></h3>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2589
Daniel Veillard9cb5ff42001-01-29 08:22:21 +0000[diff] [blame]2590<p>Basically by <a href="html/libxml-tree.html">including "tree.h"</a> your
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]2591code has access to the internal structure of all the elements of the tree.
2592The names should be somewhat simple like <strong>parent</strong>,
Daniel Veillard306be992000-07-03 12:38:45 +0000[diff] [blame]2593<strong>children</strong>, <strong>next</strong>, <strong>prev</strong>,
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]2594<strong>properties</strong>, etc... For example, still with the previous
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]2595example:</p>
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]2596<pre><code>doc-&gt;children-&gt;children-&gt;children</code></pre>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2597
2598<p>points to the title element,</p>
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]2599<pre>doc-&gt;children-&gt;children-&gt;next-&gt;children-&gt;children</pre>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2600
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]2601<p>points to the text node containing the chapter title "The Linux
2602adventure".</p>
Daniel Veillard10c6a8f1998-10-28 01:00:12 +0000[diff] [blame]2603
Daniel Veillardb24054a1999-12-18 15:32:46 +0000[diff] [blame]2604<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]2605present before the document root, so <code>doc-&gt;children</code> may point
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]2606to an element which is not the document Root Element; a function
Daniel Veillard5cb5ab81999-12-21 15:35:29 +0000[diff] [blame]2607<code>xmlDocGetRootElement()</code> was added for this purpose.</p>
Daniel Veillardb24054a1999-12-18 15:32:46 +0000[diff] [blame]2608
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]2609<h3><a name="Modifying">Modifying the tree</a></h3>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2610
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]2611<p>Functions are provided for reading and writing the document content. Here
Daniel Veillard9cb5ff42001-01-29 08:22:21 +0000[diff] [blame]2612is an excerpt from the <a href="html/libxml-tree.html">tree API</a>:</p>
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]2613<dl>
Daniel Veillarddd6b3671999-09-23 22:19:22 +0000[diff] [blame]2614 <dt><code>xmlAttrPtr xmlSetProp(xmlNodePtr node, const xmlChar *name, const
2615 xmlChar *value);</code></dt>
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]2616 <dd><p>This sets (or changes) an attribute carried by an ELEMENT node.
2617 The value can be NULL.</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2618 </dd>
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]2619</dl>
2620<dl>
Daniel Veillarddd6b3671999-09-23 22:19:22 +0000[diff] [blame]2621 <dt><code>const xmlChar *xmlGetProp(xmlNodePtr node, const xmlChar
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2622 *name);</code></dt>
Daniel Veillardc92c3042000-09-29 02:42:04 +0000[diff] [blame]2623 <dd><p>This function returns a pointer to new copy of the property
2624 content. Note that the user must deallocate the result.</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2625 </dd>
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]2626</dl>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2627
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]2628<p>Two functions are provided for reading and writing the text associated
2629with elements:</p>
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]2630<dl>
Daniel Veillarddd6b3671999-09-23 22:19:22 +0000[diff] [blame]2631 <dt><code>xmlNodePtr xmlStringGetNodeList(xmlDocPtr doc, const xmlChar
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2632 *value);</code></dt>
Daniel Veillardec70e912001-02-26 20:10:45 +0000[diff] [blame]2633 <dd><p>This function takes an "external" string and converts it to one
2634 text node or possibly to a list of entity and text nodes. All
2635 non-predefined entity references like &amp;Gnome; will be stored
2636 internally as entity nodes, hence the result of the function may not be
2637 a single node.</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2638 </dd>
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]2639</dl>
2640<dl>
Daniel Veillarddd6b3671999-09-23 22:19:22 +0000[diff] [blame]2641 <dt><code>xmlChar *xmlNodeListGetString(xmlDocPtr doc, xmlNodePtr list, int
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2642 inLine);</code></dt>
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]2643 <dd><p>This function is the inverse of
2644 <code>xmlStringGetNodeList()</code>. It generates a new string
2645 containing the content of the text and entity nodes. Note the extra
2646 argument inLine. If this argument is set to 1, the function will expand
2647 entity references. For example, instead of returning the &amp;Gnome;
2648 XML encoding in the string, it will substitute it with its value (say,
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]2649 "GNU Network Object Model Environment").</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2650 </dd>
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]2651</dl>
Daniel Veillard10c6a8f1998-10-28 01:00:12 +0000[diff] [blame]2652
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]2653<h3><a name="Saving">Saving a tree</a></h3>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2654
2655<p>Basically 3 options are possible:</p>
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]2656<dl>
Daniel Veillarddd6b3671999-09-23 22:19:22 +0000[diff] [blame]2657 <dt><code>void xmlDocDumpMemory(xmlDocPtr cur, xmlChar**mem, int
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2658 *size);</code></dt>
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]2659 <dd><p>Returns a buffer into which the document has been saved.</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2660 </dd>
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]2661</dl>
2662<dl>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2663 <dt><code>extern void xmlDocDump(FILE *f, xmlDocPtr doc);</code></dt>
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]2664 <dd><p>Dumps a document to an open file descriptor.</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2665 </dd>
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]2666</dl>
2667<dl>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2668 <dt><code>int xmlSaveFile(const char *filename, xmlDocPtr cur);</code></dt>
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]2669 <dd><p>Saves the document to a file. In this case, the compression
2670 interface is triggered if it has been turned on.</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2671 </dd>
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]2672</dl>
Daniel Veillard10c6a8f1998-10-28 01:00:12 +0000[diff] [blame]2673
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]2674<h3><a name="Compressio">Compression</a></h3>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2675
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]2676<p>The library transparently handles compression when doing file-based
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]2677accesses. The level of compression on saves can be turned on either globally
2678or individually for one file:</p>
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]2679<dl>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2680 <dt><code>int xmlGetDocCompressMode (xmlDocPtr doc);</code></dt>
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]2681 <dd><p>Gets the document compression ratio (0-9).</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2682 </dd>
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]2683</dl>
2684<dl>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2685 <dt><code>void xmlSetDocCompressMode (xmlDocPtr doc, int mode);</code></dt>
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]2686 <dd><p>Sets the document compression ratio.</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2687 </dd>
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]2688</dl>
2689<dl>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2690 <dt><code>int xmlGetCompressMode(void);</code></dt>
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]2691 <dd><p>Gets the default compression ratio.</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2692 </dd>
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]2693</dl>
2694<dl>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2695 <dt><code>void xmlSetCompressMode(int mode);</code></dt>
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]2696 <dd><p>Sets the default compression ratio.</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2697 </dd>
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]2698</dl>
2699
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]2700<h2><a name="Entities">Entities or no entities</a></h2>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]2701
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]2702<p>Entities in principle are similar to simple C macros. An entity defines an
2703abbreviation for a given string that you can reuse many times throughout the
2704content of your document. Entities are especially useful when a given string
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]2705may occur frequently within a document, or to confine the change needed to a
2706document to a restricted area in the internal subset of the document (at the
2707beginning). Example:</p>
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]2708<pre>1 &lt;?xml version="1.0"?&gt;
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]27092 &lt;!DOCTYPE EXAMPLE SYSTEM "example.dtd" [
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]27103 &lt;!ENTITY xml "Extensible Markup Language"&gt;
27114 ]&gt;
27125 &lt;EXAMPLE&gt;
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]27136 &amp;xml;
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]27147 &lt;/EXAMPLE&gt;</pre>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]2715
2716<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]2717its name with '&amp;' and following it by ';' without any spaces added. There
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]2718are 5 predefined entities in libxml allowing you to escape charaters with
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]2719predefined meaning in some parts of the xml document content:
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]2720<strong>&amp;lt;</strong> for the character '&lt;', <strong>&amp;gt;</strong>
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]2721for the character '&gt;', <strong>&amp;apos;</strong> for the character ''',
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]2722<strong>&amp;quot;</strong> for the character '"', and
2723<strong>&amp;amp;</strong> for the character '&amp;'.</p>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]2724
2725<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]2726substitute an entity's content so that you can see the replacement text in
2727your application. Or you may prefer to keep entity references as such in the
2728content to be able to save the document back without losing this usually
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]2729precious information (if the user went through the pain of explicitly
2730defining entities, he may have a a rather negative attitude if you blindly
2731susbtitute them as saving time). The <a
Daniel Veillard9cb5ff42001-01-29 08:22:21 +0000[diff] [blame]2732href="html/libxml-parser.html#XMLSUBSTITUTEENTITIESDEFAULT">xmlSubstituteEntitiesDefault()</a>
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]2733function allows you to check and change the behaviour, which is to not
2734substitute entities by default.</p>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]2735
2736<p>Here is the DOM tree built by libxml for the previous document in the
2737default case:</p>
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]2738<pre>/gnome/src/gnome-xml -&gt; ./xmllint --debug test/ent1
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]2739DOCUMENT
2740version=1.0
2741 ELEMENT EXAMPLE
2742 TEXT
2743 content=
2744 ENTITY_REF
2745 INTERNAL_GENERAL_ENTITY xml
2746 content=Extensible Markup Language
2747 TEXT
2748 content=</pre>
2749
2750<p>And here is the result when substituting entities:</p>
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]2751<pre>/gnome/src/gnome-xml -&gt; ./tester --debug --noent test/ent1
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]2752DOCUMENT
2753version=1.0
2754 ELEMENT EXAMPLE
2755 TEXT
2756 content= Extensible Markup Language</pre>
2757
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]2758<p>So, entities or no entities? Basically, it depends on your use case. I
2759suggest that you keep the non-substituting default behaviour and avoid using
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]2760entities in your XML document or data if you are not willing to handle the
2761entity references elements in the DOM tree.</p>
2762
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]2763<p>Note that at save time libxml enforces the conversion of the predefined
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]2764entities where necessary to prevent well-formedness problems, and will also
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]2765transparently replace those with chars (i.e. it will not generate entity
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]2766reference elements in the DOM tree or call the reference() SAX callback when
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]2767finding them in the input).</p>
2768
Daniel Veillard7b9c4b72000-08-25 16:26:50 +0000[diff] [blame]2769<p><span style="background-color: #FF0000">WARNING</span>: handling entities
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]2770on top of the libxml SAX interface is difficult!!! If you plan to use
Daniel Veillard7b9c4b72000-08-25 16:26:50 +0000[diff] [blame]2771non-predefined entities in your documents, then the learning cuvre to handle
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]2772then 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]2773strongly suggest you consider using the DOM interface instead and let libxml
Daniel Veillard8c6d6af2000-08-25 17:14:13 +0000[diff] [blame]2774deal with the complexity rather than trying to do it yourself.</p>
Daniel Veillard7b9c4b72000-08-25 16:26:50 +0000[diff] [blame]2775
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]2776<h2><a name="Namespaces">Namespaces</a></h2>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]2777
Daniel Veillardec303412000-03-24 13:41:54 +0000[diff] [blame]2778<p>The libxml library implements <a
2779href="http://www.w3.org/TR/REC-xml-names/">XML namespaces</a> support by
2780recognizing namespace contructs in the input, and does namespace lookup
2781automatically when building the DOM tree. A namespace declaration is
2782associated with an in-memory structure and all elements or attributes within
2783that namespace point to it. Hence testing the namespace is a simple and fast
2784equality operation at the user level.</p>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]2785
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]2786<p>I suggest that people using libxml use a namespace, and declare it in the
2787root element of their document as the default namespace. Then they don't need
2788to 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]2789refinement and merging of data from different sources. This doesn't increase
Daniel Veillardec70e912001-02-26 20:10:45 +0000[diff] [blame]2790the size of the XML output significantly, but significantly increases its
2791value in the long-term. Example:</p>
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]2792<pre>&lt;mydoc xmlns="http://mydoc.example.org/schemas/"&gt;
2793 &lt;elem1&gt;...&lt;/elem1&gt;
2794 &lt;elem2&gt;...&lt;/elem2&gt;
2795&lt;/mydoc&gt;</pre>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]2796
Daniel Veillardec70e912001-02-26 20:10:45 +0000[diff] [blame]2797<p>The namespace value has to be an absolute URL, but the URL doesn't have to
2798point to any existing resource on the Web. It will bind all the element and
2799atributes with that URL. I suggest to use an URL within a domain you control,
2800and that the URL should contain some kind of version information if possible.
2801For example, <code>"http://www.gnome.org/gnumeric/1.0/"</code> is a good
2802namespace scheme.</p>
Daniel Veillardec303412000-03-24 13:41:54 +0000[diff] [blame]2803
2804<p>Then when you load a file, make sure that a namespace carrying the
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]2805version-independent prefix is installed on the root element of your document,
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]2806and if the version information don't match something you know, warn the user
2807and 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]2808namespace checking on the prefix value. &lt;foo:text&gt; may be exactly the
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]2809same as &lt;bar:text&gt; in another document. What really matters is the URI
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]2810associated with the element or the attribute, not the prefix string (which is
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]2811just a shortcut for the full URI). In libxml, element and attributes have an
Daniel Veillardec303412000-03-24 13:41:54 +0000[diff] [blame]2812<code>ns</code> field pointing to an xmlNs structure detailing the namespace
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]2813prefix and its URI.</p>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]2814
2815<p>@@Interfaces@@</p>
2816
2817<p>@@Examples@@</p>
2818
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]2819<p>Usually people object to using namespaces together with validity checking.
2820I will try to make sure that using namespaces won't break validity checking,
2821so even if you plan to use or currently are using validation I strongly
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]2822suggest adding namespaces to your document. A default namespace scheme
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]2823<code>xmlns="http://...."</code> should not break validity even on less
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]2824flexible parsers. Using namespaces to mix and differentiate content coming
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]2825from multiple DTDs will certainly break current validation schemes. I will
2826try to provide ways to do this, but this may not be portable or
2827standardized.</p>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]2828
Daniel Veillardb8cfbd12001-10-25 10:53:28 +0000[diff] [blame^]2829<h2><a name="Upgrading">Upgrading 1.x code</a></h2>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]2830
Daniel Veillardb8cfbd12001-10-25 10:53:28 +0000[diff] [blame^]2831<p>Incompatible changes:</p>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]2832
Daniel Veillardb8cfbd12001-10-25 10:53:28 +0000[diff] [blame^]2833<p>Version 2 of libxml is the first version introducing serious backward
2834incompatible changes. The main goals were:</p>
2835<ul>
2836 <li>a general cleanup. A number of mistakes inherited from the very early
2837 versions couldn't be changed due to compatibility constraints. Example
2838 the "childs" element in the nodes.</li>
2839 <li>Uniformization of the various nodes, at least for their header and link
2840 parts (doc, parent, children, prev, next), the goal is a simpler
2841 programming model and simplifying the task of the DOM implementors.</li>
2842 <li>better conformances to the XML specification, for example version 1.x
2843 had an heuristic to try to detect ignorable white spaces. As a result the
2844 SAX event generated were ignorableWhitespace() while the spec requires
2845 character() in that case. This also mean that a number of DOM node
2846 containing blank text may populate the DOM tree which were not present
2847 before.</li>
2848</ul>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]2849
Daniel Veillardb8cfbd12001-10-25 10:53:28 +0000[diff] [blame^]2850<h3>How to fix libxml-1.x code:</h3>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]2851
Daniel Veillardb8cfbd12001-10-25 10:53:28 +0000[diff] [blame^]2852<p>So client code of libxml designed to run with version 1.x may have to be
2853changed to compile against version 2.x of libxml. Here is a list of changes
2854that I have collected, they may not be sufficient, so in case you find other
2855change which are required, <a href="mailto:Daniel.Ïeillardw3.org">drop me a
2856mail</a>:</p>
2857<ol>
2858 <li>The package name have changed from libxml to libxml2, the library name
2859 is now -lxml2 . There is a new xml2-config script which should be used to
2860 select the right parameters libxml2</li>
2861 <li>Node <strong>childs</strong> field has been renamed
2862 <strong>children</strong> so s/childs/children/g should be applied
2863 (probablility of having "childs" anywere else is close to 0+</li>
2864 <li>The document don't have anymore a <strong>root</strong> element it has
2865 been replaced by <strong>children</strong> and usually you will get a
2866 list of element here. For example a Dtd element for the internal subset
2867 and it's declaration may be found in that list, as well as processing
2868 instructions or comments found before or after the document root element.
2869 Use <strong>xmlDocGetRootElement(doc)</strong> to get the root element of
2870 a document. Alternatively if you are sure to not reference Dtds nor have
2871 PIs or comments before or after the root element
2872 s/-&gt;root/-&gt;children/g will probably do it.</li>
2873 <li>The white space issue, this one is more complex, unless special case of
2874 validating parsing, the line breaks and spaces usually used for indenting
2875 and formatting the document content becomes significant. So they are
2876 reported by SAX and if your using the DOM tree, corresponding nodes are
2877 generated. Too approach can be taken:
2878 <ol>
2879 <li>lazy one, use the compatibility call
2880 <strong>xmlKeepBlanksDefault(0)</strong> but be aware that you are
2881 relying on a special (and possibly broken) set of heuristics of
2882 libxml to detect ignorable blanks. Don't complain if it breaks or
2883 make your application not 100% clean w.r.t. to it's input.</li>
2884 <li>the Right Way: change you code to accept possibly unsignificant
2885 blanks characters, or have your tree populated with weird blank text
2886 nodes. You can spot them using the comodity function
2887 <strong>xmlIsBlankNode(node)</strong> returning 1 for such blank
2888 nodes.</li>
2889 </ol>
2890 <p>Note also that with the new default the output functions don't add any
2891 extra indentation when saving a tree in order to be able to round trip
2892 (read and save) without inflating the document with extra formatting
2893 chars.</p>
2894 </li>
2895 <li>The include path has changed to $prefix/libxml/ and the includes
2896 themselves uses this new prefix in includes instructions... If you are
2897 using (as expected) the
2898 <pre>xml2-config --cflags</pre>
2899 <p>output to generate you compile commands this will probably work out of
2900 the box</p>
2901 </li>
2902 <li>xmlDetectCharEncoding takes an extra argument indicating the lenght in
2903 byte of the head of the document available for character detection.</li>
2904</ol>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]2905
Daniel Veillardb8cfbd12001-10-25 10:53:28 +0000[diff] [blame^]2906<h3>Ensuring both libxml-1.x and libxml-2.x compatibility</h3>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]2907
Daniel Veillardb8cfbd12001-10-25 10:53:28 +0000[diff] [blame^]2908<p>Two new version of libxml (1.8.11) and libxml2 (2.3.4) have been released
2909to allow smoth upgrade of existing libxml v1code while retaining
2910compatibility. They offers the following:</p>
2911<ol>
2912 <li>similar include naming, one should use
2913 <strong>#include&lt;libxml/...&gt;</strong> in both cases.</li>
2914 <li>similar identifiers defined via macros for the child and root fields:
2915 respectively <strong>xmlChildrenNode</strong> and
2916 <strong>xmlRootNode</strong></li>
2917 <li>a new macro <strong>LIBXML_TEST_VERSION</strong> which should be
2918 inserted once in the client code</li>
2919</ol>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]2920
Daniel Veillardb8cfbd12001-10-25 10:53:28 +0000[diff] [blame^]2921<p>So the roadmap to upgrade your existing libxml applications is the
2922following:</p>
2923<ol>
2924 <li>install the libxml-1.8.8 (and libxml-devel-1.8.8) packages</li>
2925 <li>find all occurences where the xmlDoc <strong>root</strong> field is
2926 used and change it to <strong>xmlRootNode</strong></li>
2927 <li>similary find all occurences where the xmlNode <strong>childs</strong>
2928 field is used and change it to <strong>xmlChildrenNode</strong></li>
2929 <li>add a <strong>LIBXML_TEST_VERSION</strong> macro somewhere in your
2930 <strong>main()</strong> or in the library init entry point</li>
2931 <li>Recompile, check compatibility, it should still work</li>
2932 <li>Change your configure script to look first for xml2-config and fallback
2933 using xml-config . Use the --cflags and --libs ouptut of the command as
2934 the Include and Linking parameters needed to use libxml.</li>
2935 <li>install libxml2-2.3.x and libxml2-devel-2.3.x (libxml-1.8.y and
2936 libxml-devel-1.8.y can be kept simultaneously)</li>
2937 <li>remove your config.cache, relaunch your configuration mechanism, and
2938 recompile, if steps 2 and 3 were done right it should compile as-is</li>
2939 <li>Test that your application is still running correctly, if not this may
2940 be due to extra empty nodes due to formating spaces being kept in libxml2
2941 contrary to libxml1, in that case insert xmlKeepBlanksDefault(1) in your
2942 code before calling the parser (next to
2943 <strong>LIBXML_TEST_VERSION</strong> is a fine place).</li>
2944</ol>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]2945
Daniel Veillardb8cfbd12001-10-25 10:53:28 +0000[diff] [blame^]2946<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]2947
Daniel Veillardb8cfbd12001-10-25 10:53:28 +0000[diff] [blame^]2948<p>Let me put some emphasis on the fact that there is far more changes from
2949libxml 1.x to 2.x than the ones you may have to patch for. The overall code
2950has been considerably cleaned up and the conformance to the XML specification
2951has been drastically improved too. Don't take those changes as an excuse to
2952not upgrade, it may cost a lot on the long term ...</p>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]2953
Daniel Veillard35008381999-10-25 13:15:52 +0000[diff] [blame]2954<h2><a name="DOM"></a><a name="Principles">DOM Principles</a></h2>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2955
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]2956<p><a href="http://www.w3.org/DOM/">DOM</a> stands for the <em>Document
2957Object Model</em>; this is an API for accessing XML or HTML structured
2958documents. Native support for DOM in Gnome is on the way (module gnome-dom),
2959and will be based on gnome-xml. This will be a far cleaner interface to
2960manipulate XML files within Gnome since it won't expose the internal
2961structure.</p>
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]2962
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]2963<p>The current DOM implementation on top of libxml is the <a
Daniel Veillarda47fb3d2001-03-25 17:23:49 +0000[diff] [blame]2964href="http://cvs.gnome.org/lxr/source/gdome2/">gdome2 Gnome module</a>, this
2965is a full DOM interface, thanks to Paolo Casarini, check the <a
2966href="http://www.cs.unibo.it/~casarini/gdome2/">Gdome2 homepage</a> for more
2967informations.</p>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]2968
Daniel Veillard35008381999-10-25 13:15:52 +0000[diff] [blame]2969<h2><a name="Example"></a><a name="real">A real example</a></h2>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2970
2971<p>Here is a real size example, where the actual content of the application
2972data 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]2973a proposal to keep a database of jobs related to Gnome, with an XML based
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2974storage structure. Here is an <a href="gjobs.xml">XML encoded jobs
2975base</a>:</p>
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]2976<pre>&lt;?xml version="1.0"?&gt;
2977&lt;gjob:Helping xmlns:gjob="http://www.gnome.org/some-location"&gt;
2978 &lt;gjob:Jobs&gt;
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]2979
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]2980 &lt;gjob:Job&gt;
2981 &lt;gjob:Project ID="3"/&gt;
2982 &lt;gjob:Application&gt;GBackup&lt;/gjob:Application&gt;
2983 &lt;gjob:Category&gt;Development&lt;/gjob:Category&gt;
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]2984
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]2985 &lt;gjob:Update&gt;
2986 &lt;gjob:Status&gt;Open&lt;/gjob:Status&gt;
2987 &lt;gjob:Modified&gt;Mon, 07 Jun 1999 20:27:45 -0400 MET DST&lt;/gjob:Modified&gt;
2988 &lt;gjob:Salary&gt;USD 0.00&lt;/gjob:Salary&gt;
2989 &lt;/gjob:Update&gt;
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]2990
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]2991 &lt;gjob:Developers&gt;
2992 &lt;gjob:Developer&gt;
2993 &lt;/gjob:Developer&gt;
2994 &lt;/gjob:Developers&gt;
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]2995
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]2996 &lt;gjob:Contact&gt;
2997 &lt;gjob:Person&gt;Nathan Clemons&lt;/gjob:Person&gt;
2998 &lt;gjob:Email&gt;nathan@windsofstorm.net&lt;/gjob:Email&gt;
2999 &lt;gjob:Company&gt;
3000 &lt;/gjob:Company&gt;
3001 &lt;gjob:Organisation&gt;
3002 &lt;/gjob:Organisation&gt;
3003 &lt;gjob:Webpage&gt;
3004 &lt;/gjob:Webpage&gt;
3005 &lt;gjob:Snailmail&gt;
3006 &lt;/gjob:Snailmail&gt;
3007 &lt;gjob:Phone&gt;
3008 &lt;/gjob:Phone&gt;
3009 &lt;/gjob:Contact&gt;
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]3010
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]3011 &lt;gjob:Requirements&gt;
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]3012 The program should be released as free software, under the GPL.
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]3013 &lt;/gjob:Requirements&gt;
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]3014
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]3015 &lt;gjob:Skills&gt;
3016 &lt;/gjob:Skills&gt;
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]3017
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]3018 &lt;gjob:Details&gt;
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]3019 A GNOME based system that will allow a superuser to configure
3020 compressed and uncompressed files and/or file systems to be backed
3021 up with a supported media in the system. This should be able to
3022 perform via find commands generating a list of files that are passed
3023 to tar, dd, cpio, cp, gzip, etc., to be directed to the tape machine
3024 or via operations performed on the filesystem itself. Email
3025 notification and GUI status display very important.
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]3026 &lt;/gjob:Details&gt;
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]3027
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]3028 &lt;/gjob:Job&gt;
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]3029
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]3030 &lt;/gjob:Jobs&gt;
3031&lt;/gjob:Helping&gt;</pre>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]3032
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]3033<p>While loading the XML file into an internal DOM tree is a matter of
3034calling only a couple of functions, browsing the tree to gather the ata and
3035generate the internal structures is harder, and more error prone.</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]3036
3037<p>The suggested principle is to be tolerant with respect to the input
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]3038structure. For example, the ordering of the attributes is not significant,
3039the 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]3040depend on the order of the children of a given node, unless it really makes
3041things harder. Here is some code to parse the information for a person:</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]3042<pre>/*
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]3043 * A person record
3044 */
3045typedef struct person {
3046 char *name;
3047 char *email;
3048 char *company;
3049 char *organisation;
3050 char *smail;
3051 char *webPage;
3052 char *phone;
3053} person, *personPtr;
3054
3055/*
3056 * And the code needed to parse it
3057 */
3058personPtr parsePerson(xmlDocPtr doc, xmlNsPtr ns, xmlNodePtr cur) {
3059 personPtr ret = NULL;
3060
3061DEBUG("parsePerson\n");
3062 /*
3063 * allocate the struct
3064 */
3065 ret = (personPtr) malloc(sizeof(person));
3066 if (ret == NULL) {
3067 fprintf(stderr,"out of memory\n");
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]3068 return(NULL);
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]3069 }
3070 memset(ret, 0, sizeof(person));
3071
3072 /* We don't care what the top level element name is */
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]3073 cur = cur-&gt;xmlChildrenNode;
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]3074 while (cur != NULL) {
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]3075 if ((!strcmp(cur-&gt;name, "Person")) &amp;&amp; (cur-&gt;ns == ns))
3076 ret-&gt;name = xmlNodeListGetString(doc, cur-&gt;xmlChildrenNode, 1);
3077 if ((!strcmp(cur-&gt;name, "Email")) &amp;&amp; (cur-&gt;ns == ns))
3078 ret-&gt;email = xmlNodeListGetString(doc, cur-&gt;xmlChildrenNode, 1);
3079 cur = cur-&gt;next;
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]3080 }
3081
3082 return(ret);
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]3083}</pre>
3084
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]3085<p>Here are a couple of things to notice:</p>
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]3086<ul>
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]3087 <li>Usually a recursive parsing style is the more convenient one: XML data
3088 is by nature subject to repetitive constructs and usually exibits highly
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]3089 stuctured patterns.</li>
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]3090 <li>The two arguments of type <em>xmlDocPtr</em> and <em>xmlNsPtr</em>,
3091 i.e. the pointer to the global XML document and the namespace reserved to
3092 the application. Document wide information are needed for example to
3093 decode entities and it's a good coding practice to define a namespace for
3094 your application set of data and test that the element and attributes
3095 you're analyzing actually pertains to your application space. This is
3096 done by a simple equality test (cur-&gt;ns == ns).</li>
Daniel Veillardec70e912001-02-26 20:10:45 +0000[diff] [blame]3097 <li>To retrieve text and attributes value, you can use the function
3098 <em>xmlNodeListGetString</em> to gather all the text and entity reference
3099 nodes generated by the DOM output and produce an single text string.</li>
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]3100</ul>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]3101
3102<p>Here is another piece of code used to parse another level of the
3103structure:</p>
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]3104<pre>#include &lt;libxml/tree.h&gt;
Daniel Veillard361d8452000-04-03 19:48:13 +0000[diff] [blame]3105/*
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]3106 * a Description for a Job
3107 */
3108typedef struct job {
3109 char *projectID;
3110 char *application;
3111 char *category;
3112 personPtr contact;
3113 int nbDevelopers;
3114 personPtr developers[100]; /* using dynamic alloc is left as an exercise */
3115} job, *jobPtr;
3116
3117/*
3118 * And the code needed to parse it
3119 */
3120jobPtr parseJob(xmlDocPtr doc, xmlNsPtr ns, xmlNodePtr cur) {
3121 jobPtr ret = NULL;
3122
3123DEBUG("parseJob\n");
3124 /*
3125 * allocate the struct
3126 */
3127 ret = (jobPtr) malloc(sizeof(job));
3128 if (ret == NULL) {
3129 fprintf(stderr,"out of memory\n");
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]3130 return(NULL);
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]3131 }
3132 memset(ret, 0, sizeof(job));
3133
3134 /* We don't care what the top level element name is */
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]3135 cur = cur-&gt;xmlChildrenNode;
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]3136 while (cur != NULL) {
3137
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]3138 if ((!strcmp(cur-&gt;name, "Project")) &amp;&amp; (cur-&gt;ns == ns)) {
3139 ret-&gt;projectID = xmlGetProp(cur, "ID");
3140 if (ret-&gt;projectID == NULL) {
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]3141 fprintf(stderr, "Project has no ID\n");
3142 }
3143 }
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]3144 if ((!strcmp(cur-&gt;name, "Application")) &amp;&amp; (cur-&gt;ns == ns))
3145 ret-&gt;application = xmlNodeListGetString(doc, cur-&gt;xmlChildrenNode, 1);
3146 if ((!strcmp(cur-&gt;name, "Category")) &amp;&amp; (cur-&gt;ns == ns))
3147 ret-&gt;category = xmlNodeListGetString(doc, cur-&gt;xmlChildrenNode, 1);
3148 if ((!strcmp(cur-&gt;name, "Contact")) &amp;&amp; (cur-&gt;ns == ns))
3149 ret-&gt;contact = parsePerson(doc, ns, cur);
3150 cur = cur-&gt;next;
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]3151 }
3152
3153 return(ret);
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]3154}</pre>
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]3155
Daniel Veillardec70e912001-02-26 20:10:45 +0000[diff] [blame]3156<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]3157boring. Ultimately, it could be possble to write stubbers taking either C
3158data structure definitions, a set of XML examples or an XML DTD and produce
3159the code needed to import and export the content between C data and XML
3160storage. This is left as an exercise to the reader :-)</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]3161
Daniel Veillard6f0adb52000-07-03 11:41:26 +0000[diff] [blame]3162<p>Feel free to use <a href="example/gjobread.c">the code for the full C
3163parsing example</a> as a template, it is also available with Makefile in the
3164Gnome CVS base under gnome-xml/example</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]3165
Daniel Veillardc310d562000-06-23 18:32:15 +0000[diff] [blame]3166<h2><a name="Contributi">Contributions</a></h2>
3167<ul>
Daniel Veillardb8cfbd12001-10-25 10:53:28 +0000[diff] [blame^]3168 <li>Bjorn Reese, William Brack and Thomas Broyer have provided a number of
3169 patches, Gary Pennington worked on the validation API, threading support
3170 and Solaris port.</li>
3171 <li>John Fleck helps maintaining the documentation and man pages.</li>
3172 <li><p><a href="mailto:ari@lusis.org">Ari Johnson</a></p>
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]3173 provides a C++ wrapper for libxml:
Daniel Veillardc310d562000-06-23 18:32:15 +0000[diff] [blame]3174 <p>Website: <a
3175 href="http://lusis.org/~ari/xml++/">http://lusis.org/~ari/xml++/</a></p>
3176 <p>Download: <a
3177 href="http://lusis.org/~ari/xml++/libxml++.tar.gz">http://lusis.org/~ari/xml++/libxml++.tar.gz</a></p>
3178 </li>
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]3179 <li><a href="mailto:izlatkovic@daenet.de">Igor Zlatkovic</a>
3180 is now the maintainer of the Windows port, <a
Daniel Veillard95189532001-07-26 18:30:26 +0000[diff] [blame]3181 href="http://www.fh-frankfurt.de/~igor/projects/libxml/index.html">he
3182 provides binaries</a></li>
Daniel Veillardc9484202001-10-24 12:35:52 +0000[diff] [blame]3183 <li><a href="mailto:Gary.Pennington@sun.com">Gary Pennington</a>
3184 provides <a href="http://pages.eidosnet.co.uk/~garypen/libxml/">Solaris
Daniel Veillard0a702dc2001-10-19 14:50:57 +0000[diff] [blame]3185 binaries</a></li>
Daniel Veillarde356c282001-03-10 12:32:04 +0000[diff] [blame]3186 <li><a
3187 href="http://mail.gnome.org/archives/xml/2001-March/msg00014.html">Matt
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]3188 Sergeant</a>
3189 developped <a href="http://axkit.org/download/">XML::LibXSLT</a>, a perl
3190 wrapper for libxml2/libxslt as part of the <a
3191 href="http://axkit.com/">AxKit XML application server</a></li>
3192 <li><a href="mailto:fnatter@gmx.net">Felix Natter</a>
3193 and <a href="mailto:geertk@ai.rug.nl">Geert Kloosterman</a> provide <a
Daniel Veillardca989762001-06-23 17:39:29 +0000[diff] [blame]3194 href="libxml-doc.el">an emacs module</a> to lookup libxml(2) functions
Daniel Veillard3f6f7f62000-06-30 17:58:25 +0000[diff] [blame]3195 documentation</li>
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]3196 <li><a href="mailto:sherwin@nlm.nih.gov">Ziying Sherwin</a>
3197 provided <a href="http://xmlsoft.org/messages/0488.html">man
3198 pages</a></li>
Daniel Veillard5168dbf2001-07-07 00:18:23 +0000[diff] [blame]3199 <li>there is a module for <a
3200 href="http://acs-misc.sourceforge.net/nsxml.html">libxml/libxslt support
3201 in OpenNSD/AOLServer</a></li>
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]3202 <li><a href="mailto:dkuhlman@cutter.rexx.com">Dave Kuhlman</a>
3203 provides libxml/libxslt <a href="http://www.rexx.com/~dkuhlman">wrappers
3204 for Python</a></li>
Daniel Veillardc310d562000-06-23 18:32:15 +0000[diff] [blame]3205</ul>
3206
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]3207<p></p>
3208
Daniel Veillardf7ed3362001-08-17 12:01:21 +0000[diff] [blame]3209<p><a href="mailto:daniel@veillard.com">Daniel Veillard</a></p>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]3210
Daniel Veillardb8cfbd12001-10-25 10:53:28 +0000[diff] [blame^]3211<p>$Id: xml.html,v 1.114 2001/10/24 12:35:52 veillard Exp $</p>
Daniel Veillardccb09631998-10-27 06:21:04 +0000[diff] [blame]3212</body>
3213</html>