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blob: 6dcd5a43d1486efcea0e2ed7bd0c64a26cc35eaa [file] [log] [blame]
Daniel Veillard09ab7e12001-07-10 15:49:44 +0000[diff] [blame]1<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"
2 "http://www.w3.org/TR/html4/loose.dtd">
Daniel Veillardccb09631998-10-27 06:21:04 +0000[diff] [blame]3<html>
4<head>
Daniel Veillardec78c0f2000-08-25 10:25:23 +0000[diff] [blame]5 <title>The XML C library for Gnome</title>
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]6 <meta name="GENERATOR" content="amaya V5.0">
Daniel Veillardb24054a1999-12-18 15:32:46 +0000[diff] [blame]7 <meta http-equiv="Content-Type" content="text/html">
Daniel Veillardccb09631998-10-27 06:21:04 +0000[diff] [blame]8</head>
Daniel Veillardccb09631998-10-27 06:21:04 +0000[diff] [blame]9
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]10<body bgcolor="#ffffff">
Daniel Veillardec78c0f2000-08-25 10:25:23 +0000[diff] [blame]11<h1 align="center">The XML C library for Gnome</h1>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]12
Daniel Veillard9c466822001-10-25 12:03:39 +0000[diff] [blame]13<h1>Note: this is the flat content of the <a href="index.html">web
14site</a></h1>
15
Daniel Veillardc9484202001-10-24 12:35:52 +0000[diff] [blame]16<h1 style="text-align: center">libxml, a.k.a. gnome-xml</h1>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]17
18<p></p>
Daniel Veillard9c466822001-10-25 12:03:39 +0000[diff] [blame]19
20<p>Libxml is the XML C library developped for the Gnome project. XML itself
21is a metalanguage to design markup languages, i.e. text language where
22semantic and structure are added to the content using extra "markup"
23information enclosed between angle bracket. HTML is the most well-known
24markup language.</p>
25
26<p>Libxml2 implements a number of existing standards related to markup
27languages:</p>
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]28<ul>
Daniel Veillard9c466822001-10-25 12:03:39 +0000[diff] [blame]29 <li>the XML standard: <a
30 href="http://www.w3.org/TR/REC-xml">http://www.w3.org/TR/REC-xml</a></li>
31 <li>Namespaces in XML: <a
32 href="http://www.w3.org/TR/REC-xml-names/">http://www.w3.org/TR/REC-xml-names/</a></li>
33 <li>XML Base: <a
34 href="http://www.w3.org/TR/xmlbase/">http://www.w3.org/TR/xmlbase/</a></li>
35 <li><a href="http://www.cis.ohio-state.edu/rfc/rfc2396.txt">RFC 2396</a>
Daniel Veillardc6271d22001-10-27 07:50:58 +0000[diff] [blame]36 : Uniform Resource Identifiers <a
Daniel Veillard9c466822001-10-25 12:03:39 +0000[diff] [blame]37 href="http://www.ietf.org/rfc/rfc2396.txt">http://www.ietf.org/rfc/rfc2396.txt</a></li>
38 <li>XML Path Language (XPath) 1.0: <a
39 href="http://www.w3.org/TR/xpath">http://www.w3.org/TR/xpath</a></li>
40 <li>HTML4 parser: <a
41 href="http://www.w3.org/TR/html401/">http://www.w3.org/TR/html401/</a></li>
42 <li>most of XML Pointer Language (XPointer) Version 1.0: <a
43 href="http://www.w3.org/TR/xptr">http://www.w3.org/TR/xptr</a></li>
44 <li>XML Inclusions (XInclude) Version 1.0: <a
45 href="http://www.w3.org/TR/xinclude/">http://www.w3.org/TR/xinclude/</a></li>
46 <li>[ISO-8859-1], <a
47 href="http://www.cis.ohio-state.edu/rfc/rfc2044.txt">rfc2044</a> [UTF-8]
48 and <a href="http://www.cis.ohio-state.edu/rfc/rfc2781.txt">rfc2781</a>
49 [UTF-16] core encodings</li>
50 <li>part of SGML Open Technical Resolution TR9401:1997</li>
51 <li>XML Catalogs Working Draft 06 August 2001: <a
52 href="http://www.oasis-open.org/committees/entity/spec-2001-08-06.html">http://www.oasis-open.org/committees/entity/spec-2001-08-06.html</a></li>
Daniel Veillard96984452000-08-31 13:50:12 +0000[diff] [blame]53</ul>
54
Daniel Veillard9c466822001-10-25 12:03:39 +0000[diff] [blame]55<p>In most cases libxml tries to implement the specifications in a relatively
56strict way. To some extent libxml2 provide some support for the following
57other specification but don't claim to implement them:</p>
58<ul>
59 <li>Document Object Model (DOM) <a
60 href="http://www.w3.org/TR/DOM-Level-2-Core/">http://www.w3.org/TR/DOM-Level-2-Core/</a>
61 it doesn't implement the API itself, gdome2 does this in top of
62 libxml2</li>
63 <li><a href="http://www.cis.ohio-state.edu/rfc/rfc959.txt">RFC 959</a>
Daniel Veillardc6271d22001-10-27 07:50:58 +0000[diff] [blame]64 : libxml implements a basic FTP client code</li>
Daniel Veillard9c466822001-10-25 12:03:39 +0000[diff] [blame]65 <li><a href="http://www.cis.ohio-state.edu/rfc/rfc1945.txt">RFC 1945</a>
Daniel Veillardc6271d22001-10-27 07:50:58 +0000[diff] [blame]66 : HTTP/1.0, again a basic HTTP client code</li>
Daniel Veillard9c466822001-10-25 12:03:39 +0000[diff] [blame]67 <li>SAX: a minimal SAX implementation compatible with early expat
68 versions</li>
69 <li>DocBook SGML v4: libxml2 includes a hackish parser to transition to
70 XML</li>
71</ul>
72
73<p></p>
74
Daniel Veillard96984452000-08-31 13:50:12 +0000[diff] [blame]75<p>Separate documents:</p>
76<ul>
Daniel Veillardc6271d22001-10-27 07:50:58 +0000[diff] [blame]77 <li><a href="http://xmlsoft.org/XSLT/">the libxslt page</a>
78 providing an implementation of XSLT 1.0 and extensions on top of
79 libxml2</li>
80 <li><a href="http://www.cs.unibo.it/~casarini/gdome2/">the gdome2 page</a>
Daniel Veillard51095312001-10-28 18:51:57 +0000[diff] [blame]81 : a standard DOM2 implementation based on libxml2</li>
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]82</ul>
83
84<h2><a name="Introducti">Introduction</a></h2>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]85
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]86<p>This document describes libxml, the <a
Daniel Veillardec78c0f2000-08-25 10:25:23 +0000[diff] [blame]87href="http://www.w3.org/XML/">XML</a> C library developped for the <a
88href="http://www.gnome.org/">Gnome</a> project. <a
89href="http://www.w3.org/XML/">XML is a standard</a> for building tag-based
90structured documents/data.</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]91
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]92<p>Here are some key points about libxml:</p>
93<ul>
Daniel Veillard189446d2000-10-13 10:23:06 +0000[diff] [blame]94 <li>Libxml exports Push and Pull type parser interfaces for both XML and
95 HTML.</li>
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]96 <li>Libxml can do DTD validation at parse time, using a parsed document
97 instance, or with an arbitrary DTD.</li>
98 <li>Libxml now includes nearly complete <a
Daniel Veillard8c2ecaf2001-07-10 17:53:07 +0000[diff] [blame]99 href="http://www.w3.org/TR/xpath">XPath</a>, <a
100 href="http://www.w3.org/TR/xptr">XPointer</a> and <a
101 href="http://www.w3.org/TR/xinclude">XInclude</a> implementations.</li>
Daniel Veillardec78c0f2000-08-25 10:25:23 +0000[diff] [blame]102 <li>It is written in plain C, making as few assumptions as possible, and
Daniel Veillard189446d2000-10-13 10:23:06 +0000[diff] [blame]103 sticking closely to ANSI C/POSIX for easy embedding. Works on
Daniel Veillardab8500d2000-10-15 21:06:19 +0000[diff] [blame]104 Linux/Unix/Windows, ported to a number of other platforms.</li>
Daniel Veillardec70e912001-02-26 20:10:45 +0000[diff] [blame]105 <li>Basic support for HTTP and FTP client allowing aplications to fetch
106 remote resources</li>
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]107 <li>The design is modular, most of the extensions can be compiled out.</li>
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]108 <li>The internal document repesentation is as close as possible to the <a
109 href="http://www.w3.org/DOM/">DOM</a> interfaces.</li>
110 <li>Libxml also has a <a href="http://www.megginson.com/SAX/index.html">SAX
Daniel Veillard402e8c82000-02-29 22:57:47 +0000[diff] [blame]111 like interface</a>; the interface is designed to be compatible with <a
112 href="http://www.jclark.com/xml/expat.html">Expat</a>.</li>
Daniel Veillardec303412000-03-24 13:41:54 +0000[diff] [blame]113 <li>This library is released both under the <a
114 href="http://www.w3.org/Consortium/Legal/copyright-software-19980720.html">W3C
Daniel Veillard189446d2000-10-13 10:23:06 +0000[diff] [blame]115 IPR</a> and the <a href="http://www.gnu.org/copyleft/lesser.html">GNU
116 LGPL</a>. Use either at your convenience, basically this should make
117 everybody happy, if not, drop me a mail.</li>
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]118</ul>
Daniel Veillardccb09631998-10-27 06:21:04 +0000[diff] [blame]119
Daniel Veillarde0c1d722001-03-21 10:28:36 +0000[diff] [blame]120<p>Warning: unless you are forced to because your application links with a
121Gnome library requiring it, <strong><span
122style="background-color: #FF0000">Do Not Use libxml1</span></strong>, use
123libxml2</p>
124
Daniel Veillardb8cfbd12001-10-25 10:53:28 +0000[diff] [blame]125<h2><a name="FAQ">FAQ</a></h2>
126
127<p>Table of Content:</p>
128<ul>
129 <li><a href="FAQ.html#Licence">Licence(s)</a></li>
130 <li><a href="FAQ.html#Installati">Installation</a></li>
131 <li><a href="FAQ.html#Compilatio">Compilation</a></li>
132 <li><a href="FAQ.html#Developer">Developer corner</a></li>
133</ul>
134
135<h3><a name="Licence">Licence</a>(s)</h3>
136<ol>
137 <li><em>Licensing Terms for libxml</em>
138 <p>libxml is released under 2 (compatible) licences:</p>
139 <ul>
140 <li>the <a href="http://www.gnu.org/copyleft/lgpl.html">LGPL</a>: GNU
141 Library General Public License</li>
142 <li>the <a
143 href="http://www.w3.org/Consortium/Legal/copyright-software-19980720.html">W3C
144 IPR</a>: very similar to the XWindow licence</li>
145 </ul>
146 </li>
147 <li><em>Can I embed libxml in a proprietary application ?</em>
148 <p>Yes. The W3C IPR allows you to also keep proprietary the changes you
149 made to libxml, but it would be graceful to provide back bugfixes and
150 improvements as patches for possible incorporation in the main
151 development tree</p>
152 </li>
153</ol>
154
155<h3><a name="Installati">Installation</a></h3>
156<ol>
157 <li>Unless you are forced to because your application links with a Gnome
158 library requiring it, <strong><span style="background-color: #FF0000">Do
159 Not Use libxml1</span></strong>, use libxml2</li>
160 <li><em>Where can I get libxml</em>
161 ?
162 <p>The original distribution comes from <a
163 href="ftp://rpmfind.net/pub/libxml/">rpmfind.net</a> or <a
164 href="ftp://ftp.gnome.org/pub/GNOME/stable/sources/libxml/">gnome.org</a></p>
165 <p>Most linux and Bsd distribution includes libxml, this is probably the
166 safer way for end-users</p>
167 <p>David Doolin provides precompiled Windows versions at <a
168 href="http://www.ce.berkeley.edu/~doolin/code/libxmlwin32/ ">http://www.ce.berkeley.edu/~doolin/code/libxmlwin32/</a></p>
169 </li>
170 <li><em>I see libxml and libxml2 releases, which one should I install ?</em>
171 <ul>
172 <li>If you are not concerned by any existing backward compatibility
173 with existing application, install libxml2 only</li>
174 <li>If you are not doing development, you can safely install both.
175 usually the packages <a
176 href="http://rpmfind.net/linux/RPM/libxml.html">libxml</a> and <a
177 href="http://rpmfind.net/linux/RPM/libxml2.html">libxml2</a> are
178 compatible (this is not the case for development packages)</li>
179 <li>If you are a developer and your system provides separate packaging
180 for shared libraries and the development components, it is possible
181 to install libxml and libxml2, and also <a
182 href="http://rpmfind.net/linux/RPM/libxml-devel.html">libxml-devel</a>
183 and <a
184 href="http://rpmfind.net/linux/RPM/libxml2-devel.html">libxml2-devel</a>
185 too for libxml2 &gt;= 2.3.0</li>
186 <li>If you are developing a new application, please develop against
187 libxml2(-devel)</li>
188 </ul>
189 </li>
190 <li><em>I can't install the libxml package it conflicts with libxml0</em>
191 <p>You probably have an old libxml0 package used to provide the shared
192 library for libxml.so.0, you can probably safely remove it. Anyway the
193 libxml packages provided on <a
194 href="ftp://rpmfind.net/pub/libxml/">rpmfind.net</a> provides
195 libxml.so.0</p>
196 </li>
197 <li><em>I can't install the libxml(2) RPM package due to failed
198 dependancies</em>
199 <p>The most generic solution is to refetch the latest src.rpm , and
200 rebuild it locally with</p>
201 <p><code>rpm --rebuild libxml(2)-xxx.src.rpm</code></p>
202 <p>if everything goes well it will generate two binary rpm (one providing
203 the shared libs and xmllint, and the other one, the -devel package
204 providing includes, static libraries and scripts needed to build
205 applications with libxml(2)) that you can install locally.</p>
206 </li>
207</ol>
208
209<h3><a name="Compilatio">Compilation</a></h3>
210<ol>
211 <li><em>What is the process to compile libxml ?</em>
212 <p>As most UNIX libraries libxml follows the "standard":</p>
213 <p><code>gunzip -c xxx.tar.gz | tar xvf -</code></p>
214 <p><code>cd libxml-xxxx</code></p>
215 <p><code>./configure --help</code></p>
216 <p>to see the options, then the compilation/installation proper</p>
217 <p><code>./configure [possible options]</code></p>
218 <p><code>make</code></p>
219 <p><code>make install</code></p>
220 <p>At that point you may have to rerun ldconfig or similar utility to
221 update your list of installed shared libs.</p>
222 </li>
223 <li><em>What other libraries are needed to compile/install libxml ?</em>
224 <p>Libxml does not requires any other library, the normal C ANSI API
225 should be sufficient (please report any violation to this rule you may
226 find).</p>
227 <p>However if found at configuration time libxml will detect and use the
228 following libs:</p>
229 <ul>
230 <li><a href="http://www.info-zip.org/pub/infozip/zlib/">libz</a>
231 : a highly portable and available widely compression library</li>
232 <li>iconv: a powerful character encoding conversion library. It's
233 included by default on recent glibc libraries, so it doesn't need to
234 be installed specifically on linux. It seems it's now <a
235 href="http://www.opennc.org/onlinepubs/7908799/xsh/iconv.html">part
236 of the official UNIX</a> specification. Here is one <a
237 href="http://clisp.cons.org/~haible/packages-libiconv.html">implementation
238 of the library</a> which source can be found <a
239 href="ftp://ftp.ilog.fr/pub/Users/haible/gnu/">here</a>.</li>
240 </ul>
241 </li>
242 <li><em>libxml does not compile with HP-UX's optional ANSI-C compiler</em>
243 <p>this is due to macro limitations. Try to add " -Wp,-H16800 -Ae" to the
244 CFLAGS</p>
245 <p>you can also install and use gcc instead or use a precompiled version
246 of libxml, both available from the <a
247 href="http://hpux.cae.wisc.edu/hppd/auto/summary_all.html">HP-UX Porting
248 and Archive Centre</a></p>
249 </li>
250 <li><em>make check fails on some platforms</em>
251 <p>Sometime the regression tests results don't completely match the value
252 produced by the parser, and the makefile uses diff to print the delta. On
253 some platforms the diff return breaks the compilation process, if the
254 diff is small this is probably not a serious problem</p>
255 </li>
256 <li><em>I use the CVS version and there is no configure script</em>
257 <p>The configure (and other Makefiles) are generated. Use the autogen.sh
258 script to regenerate the configure and Makefiles, like:</p>
259 <p><code>./autogen.sh --prefix=/usr --disable-shared</code></p>
260 </li>
261 <li><em>I have troubles when running make tests with gcc-3.0</em>
262 <p>It seems the initial release of gcc-3.0 has a problem with the
263 optimizer which miscompiles the URI module. Please use another
264 compiler</p>
265 </li>
266</ol>
267
268<h3><a name="Developer">Developer</a> corner</h3>
269<ol>
270 <li><em>xmlDocDump() generates output on one line</em>
271 <p>libxml will not <strong>invent</strong> spaces in the content of a
272 document since <strong>all spaces in the content of a document are
273 significant</strong>. If you build a tree from the API and want
274 indentation:</p>
275 <ol>
276 <li>the correct way is to generate those yourself too</li>
277 <li>the dangerous way is to ask libxml to add those blanks to your
278 content <strong>modifying the content of your document in the
279 process</strong>. The result may not be what you expect. There is
280 <strong>NO</strong> way to guarantee that such a modification won't
281 impact other part of the content of your document. See <a
282 href="http://xmlsoft.org/html/libxml-parser.html#XMLKEEPBLANKSDEFAULT">xmlKeepBlanksDefault
283 ()</a> and <a
284 href="http://xmlsoft.org/html/libxml-tree.html#XMLSAVEFORMATFILE">xmlSaveFormatFile
285 ()</a></li>
286 </ol>
287 </li>
288 <li>Extra nodes in the document:
289 <p><em>For a XML file as below:</em></p>
290 <pre>&lt;?xml version="1.0"?&gt;
291&lt;PLAN xmlns="http://www.argus.ca/autotest/1.0/"&gt;
292&lt;NODE CommFlag="0"/&gt;
293&lt;NODE CommFlag="1"/&gt;
294&lt;/PLAN&gt;</pre>
295 <p><em>after parsing it with the function
296 pxmlDoc=xmlParseFile(...);</em></p>
297 <p><em>I want to the get the content of the first node (node with the
298 CommFlag="0")</em></p>
299 <p><em>so I did it as following;</em></p>
300 <pre>xmlNodePtr pode;
301pnode=pxmlDoc-&gt;children-&gt;children;</pre>
302 <p><em>but it does not work. If I change it to</em></p>
303 <pre>pnode=pxmlDoc-&gt;children-&gt;children-&gt;next;</pre>
304 <p><em>then it works. Can someone explain it to me.</em></p>
305 <p></p>
306 <p>In XML all characters in the content of the document are significant
307 <strong>including blanks and formatting line breaks</strong>.</p>
308 <p>The extra nodes you are wondering about are just that, text nodes with
309 the formatting spaces wich are part of the document but that people tend
310 to forget. There is a function <a
311 href="http://xmlsoft.org/html/libxml-parser.html">xmlKeepBlanksDefault
312 ()</a> to remove those at parse time, but that's an heuristic, and its
313 use should be limited to case where you are sure there is no
314 mixed-content in the document.</p>
315 </li>
316 <li><em>I get compilation errors of existing code like when accessing
317 <strong>root</strong> or <strong>childs fields</strong> of nodes</em>
318 <p>You are compiling code developed for libxml version 1 and using a
319 libxml2 development environment. Either switch back to libxml v1 devel or
320 even better fix the code to compile with libxml2 (or both) by <a
321 href="upgrade.html">following the instructions</a>.</p>
322 </li>
323 <li><em>I get compilation errors about non existing
324 <strong>xmlRootNode</strong> or <strong>xmlChildrenNode</strong>
325 fields</em>
326 <p>The source code you are using has been <a
327 href="upgrade.html">upgraded</a> to be able to compile with both libxml
328 and libxml2, but you need to install a more recent version:
329 libxml(-devel) &gt;= 1.8.8 or libxml2(-devel) &gt;= 2.1.0</p>
330 </li>
331 <li><em>XPath implementation looks seriously broken</em>
332 <p>XPath implementation prior to 2.3.0 was really incomplete, upgrade to
333 a recent version, the implementation and debug of libxslt generated fixes
334 for most obvious problems.</p>
335 </li>
336 <li><em>The example provided in the web page does not compile</em>
337 <p>It's hard to maintain the documentation in sync with the code
338 &lt;grin/&gt; ...</p>
339 <p>Check the previous points 1/ and 2/ raised before, and send
340 patches.</p>
341 </li>
342 <li><em>Where can I get more examples and informations than in the web
343 page</em>
344 <p>Ideally a libxml book would be nice. I have no such plan ... But you
345 can:</p>
346 <ul>
347 <li>check more deeply the <a href="html/libxml-lib.html">existing
348 generated doc</a></li>
349 <li>looks for examples of use for libxml function using the Gnome code
350 for example the following will query the full Gnome CVs base for the
351 use of the <strong>xmlAddChild()</strong> function:
352 <p><a
353 href="http://cvs.gnome.org/lxr/search?string=xmlAddChild">http://cvs.gnome.org/lxr/search?string=xmlAddChild</a></p>
354 <p>This may be slow, a large hardware donation to the gnome project
355 could cure this :-)</p>
356 </li>
357 <li><a
358 href="http://cvs.gnome.org/bonsai/rview.cgi?cvsroot=/cvs/gnome&amp;dir=gnome-xml">Browse
359 the libxml source</a>
360 , I try to write code as clean and documented as possible, so
361 looking at it may be helpful</li>
362 </ul>
363 </li>
364 <li>What about C++ ?
365 <p>libxml is written in pure C in order to allow easy reuse on a number
366 of platforms, including embedded systems. I don't intend to convert to
367 C++.</p>
368 <p>There is however a C++ wrapper provided by Ari Johnson
369 &lt;ari@btigate.com&gt; which may fullfill your needs:</p>
370 <p>Website: <a
371 href="http://lusis.org/~ari/xml++/">http://lusis.org/~ari/xml++/</a></p>
372 <p>Download: <a
373 href="http://lusis.org/~ari/xml++/libxml++.tar.gz">http://lusis.org/~ari/xml++/libxml++.tar.gz</a></p>
374 </li>
375 <li>How to validate a document a posteriori ?
376 <p>It is possible to validate documents which had not been validated at
377 initial parsing time or documents who have been built from scratch using
378 the API. Use the <a
379 href="http://xmlsoft.org/html/libxml-valid.html#XMLVALIDATEDTD">xmlValidateDtd()</a>
380 function. It is also possible to simply add a Dtd to an existing
381 document:</p>
382 <pre>xmlDocPtr doc; /* your existing document */
383 xmlDtdPtr dtd = xmlParseDTD(NULL, filename_of_dtd); /* parse the DTD */
384 dtd-&gt;name = xmlStrDup((xmlChar*)"root_name"); /* use the given root */
385
386 doc-&gt;intSubset = dtd;
387 if (doc-&gt;children == NULL) xmlAddChild((xmlNodePtr)doc, (xmlNodePtr)dtd);
388 else xmlAddPrevSibling(doc-&gt;children, (xmlNodePtr)dtd);
389 </pre>
390 </li>
391 <li>etc ...</li>
392</ol>
393
394<p></p>
395
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]396<h2><a name="Documentat">Documentation</a></h2>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]397
Daniel Veillard402e8c82000-02-29 22:57:47 +0000[diff] [blame]398<p>There are some on-line resources about using libxml:</p>
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]399<ol>
Daniel Veillard365e13b2000-07-02 07:56:37 +0000[diff] [blame]400 <li>Check the <a href="FAQ.html">FAQ</a></li>
Daniel Veillardc19fccc2000-07-03 11:52:01 +0000[diff] [blame]401 <li>Check the <a href="http://xmlsoft.org/html/libxml-lib.html">extensive
Daniel Veillard8c6d6af2000-08-25 17:14:13 +0000[diff] [blame]402 documentation</a> automatically extracted from code comments (using <a
403 href="http://cvs.gnome.org/bonsai/rview.cgi?cvsroot=/cvs/gnome&amp;dir=gtk-doc">gtk
404 doc</a>).</li>
Daniel Veillard8d869642000-07-14 12:12:59 +0000[diff] [blame]405 <li>Look at the documentation about <a href="encoding.html">libxml
406 internationalization support</a></li>
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]407 <li>This page provides a global overview and <a href="#real">some
Daniel Veillard402e8c82000-02-29 22:57:47 +0000[diff] [blame]408 examples</a> on how to use libxml.</li>
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]409 <li><a href="mailto:james@daa.com.au">James Henstridge</a>
410 wrote <a
Daniel Veillard402e8c82000-02-29 22:57:47 +0000[diff] [blame]411 href="http://www.daa.com.au/~james/gnome/xml-sax/xml-sax.html">some nice
412 documentation</a> explaining how to use the libxml SAX interface.</li>
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]413 <li>George Lebl wrote <a
414 href="http://www-4.ibm.com/software/developer/library/gnome3/">an article
Daniel Veillard402e8c82000-02-29 22:57:47 +0000[diff] [blame]415 for IBM developerWorks</a> about using libxml.</li>
Daniel Veillardec303412000-03-24 13:41:54 +0000[diff] [blame]416 <li>Check <a href="http://cvs.gnome.org/lxr/source/gnome-xml/TODO">the TODO
417 file</a></li>
418 <li>Read the <a href="upgrade.html">1.x to 2.x upgrade path</a>. If you are
419 starting a new project using libxml you should really use the 2.x
420 version.</li>
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]421 <li>And don't forget to look at the <a href="/messages/">mailing-list
Daniel Veillardc310d562000-06-23 18:32:15 +0000[diff] [blame]422 archive</a>.</li>
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]423</ol>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]424
Daniel Veillardd5f97f82000-09-17 16:38:14 +0000[diff] [blame]425<h2><a name="Reporting">Reporting bugs and getting help</a></h2>
Daniel Veillard4c3a2031999-11-19 17:46:26 +0000[diff] [blame]426
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]427<p>Well, bugs or missing features are always possible, and I will make a
428point of fixing them in a timely fashion. The best way to report a bug is to
429use the <a href="http://bugzilla.gnome.org/buglist.cgi?product=libxml">Gnome
430bug tracking database</a> (make sure to use the "libxml" module name). I look
431at reports there regularly and it's good to have a reminder when a bug is
Daniel Veillard51095312001-10-28 18:51:57 +0000[diff] [blame]432still open. Be sure to specify that the bug is for the package libxml.</p>
Daniel Veillard4c3a2031999-11-19 17:46:26 +0000[diff] [blame]433
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]434<p>There is also a mailing-list <a
Daniel Veillard3197f162001-04-04 00:40:08 +0000[diff] [blame]435href="mailto:xml@gnome.org">xml@gnome.org</a> for libxml, with an <a
436href="http://mail.gnome.org/archives/xml/">on-line archive</a> (<a
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]437href="http://xmlsoft.org/messages">old</a>). To subscribe to this list,
438please visit the <a
439href="http://mail.gnome.org/mailman/listinfo/xml">associated Web</a> page and
440follow the instructions. <strong>Do not send code, I won't debug it</strong>
441(but patches are really appreciated!).</p>
Daniel Veillard234547b2001-07-05 09:46:10 +0000[diff] [blame]442
Daniel Veillard008186f2001-09-13 14:24:44 +0000[diff] [blame]443<p>Check the following <strong><span style="color: #FF0000">before
444posting</span></strong>:</p>
Daniel Veillard234547b2001-07-05 09:46:10 +0000[diff] [blame]445<ul>
Daniel Veillarddadd0872001-09-15 09:21:44 +0000[diff] [blame]446 <li>read the <a href="FAQ.html">FAQ</a></li>
Daniel Veillard234547b2001-07-05 09:46:10 +0000[diff] [blame]447 <li>make sure you are <a href="ftp://xmlsoft.org/">using a recent
448 version</a>, and that the problem still shows up in those</li>
449 <li>check the <a href="http://mail.gnome.org/archives/xml/">list
450 archives</a> to see if the problem was reported already, in this case
Daniel Veillarde7ead2d2001-08-22 23:44:09 +0000[diff] [blame]451 there is probably a fix available, similary check the <a
452 href="http://bugzilla.gnome.org/buglist.cgi?product=libxml">registered
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]453 open bugs</a></li>
Daniel Veillard234547b2001-07-05 09:46:10 +0000[diff] [blame]454 <li>make sure you can reproduce the bug with xmllint or one of the test
455 programs found in source in the distribution</li>
456 <li>Please send the command showing the error as well as the input (as an
457 attachement)</li>
458</ul>
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]459
Daniel Veillarddadd0872001-09-15 09:21:44 +0000[diff] [blame]460<p>Then send the bug with associated informations to reproduce it to the <a
Daniel Veillard33a67802001-03-07 09:44:02 +0000[diff] [blame]461href="mailto:xml@gnome.org">xml@gnome.org</a> list; if it's really libxml
Daniel Veillard008186f2001-09-13 14:24:44 +0000[diff] [blame]462related I will approve it.. Please do not send me mail directly, it makes
463things really harder to track and in some cases I'm not the best person to
464answer a given question, ask the list instead.</p>
Daniel Veillard4c3a2031999-11-19 17:46:26 +0000[diff] [blame]465
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]466<p>Of course, bugs reported with a suggested patch for fixing them will
Daniel Veillardec303412000-03-24 13:41:54 +0000[diff] [blame]467probably be processed faster.</p>
468
469<p>If you're looking for help, a quick look at <a
Daniel Veillardf7ed3362001-08-17 12:01:21 +0000[diff] [blame]470href="http://mail.gnome.org/archives/xml/">the list archive</a> may actually
Daniel Veillardec303412000-03-24 13:41:54 +0000[diff] [blame]471provide the answer, I usually send source samples when answering libxml usage
Daniel Veillard6f0adb52000-07-03 11:41:26 +0000[diff] [blame]472questions. The <a href="http://xmlsoft.org/html/book1.html">auto-generated
Daniel Veillardec303412000-03-24 13:41:54 +0000[diff] [blame]473documentantion</a> is not as polished as I would like (i need to learn more
474about Docbook), but it's a good starting point.</p>
475
Daniel Veillardd5f97f82000-09-17 16:38:14 +0000[diff] [blame]476<h2><a name="help">How to help</a></h2>
477
478<p>You can help the project in various ways, the best thing to do first is to
479subscribe to the mailing-list as explained before, check the <a
Daniel Veillardf7ed3362001-08-17 12:01:21 +0000[diff] [blame]480href="http://mail.gnome.org/archives/xml/">archives </a>and the <a
481href="http://bugzilla.gnome.org/buglist.cgi?product=libxml">Gnome bug
Daniel Veillardd5f97f82000-09-17 16:38:14 +0000[diff] [blame]482database:</a>:</p>
483<ol>
484 <li>provide patches when you find problems</li>
Daniel Veillard189446d2000-10-13 10:23:06 +0000[diff] [blame]485 <li>provide the diffs when you port libxml to a new platform. They may not
Daniel Veillardab8500d2000-10-15 21:06:19 +0000[diff] [blame]486 be integrated in all cases but help pinpointing portability problems
487 and</li>
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]488 <li>provide documentation fixes (either as patches to the code comments or
Daniel Veillardd5f97f82000-09-17 16:38:14 +0000[diff] [blame]489 as HTML diffs).</li>
490 <li>provide new documentations pieces (translations, examples, etc ...)</li>
491 <li>Check the TODO file and try to close one of the items</li>
492 <li>take one of the points raised in the archive or the bug database and
Daniel Veillarde7ead2d2001-08-22 23:44:09 +0000[diff] [blame]493 provide a fix. <a href="mailto:daniel@veillard.com">Get in touch with me
494 </a>before to avoid synchronization problems and check that the suggested
495 fix will fit in nicely :-)</li>
Daniel Veillardd5f97f82000-09-17 16:38:14 +0000[diff] [blame]496</ol>
497
Daniel Veillard10a2c651999-12-12 13:03:50 +0000[diff] [blame]498<h2><a name="Downloads">Downloads</a></h2>
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]499
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]500<p>The latest versions of libxml can be found on <a
Daniel Veillard20c8cf22001-06-26 22:47:36 +0000[diff] [blame]501href="ftp://xmlsoft.org/">xmlsoft.org</a> (<a
502href="ftp://speakeasy.rpmfind.net/pub/libxml/">Seattle</a>, <a
503href="ftp://fr.rpmfind.net/pub/libxml/">France</a>) or on the <a
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]504href="ftp://ftp.gnome.org/pub/GNOME/MIRRORS.html">Gnome FTP server</a> either
Daniel Veillard10a2c651999-12-12 13:03:50 +0000[diff] [blame]505as a <a href="ftp://ftp.gnome.org/pub/GNOME/stable/sources/libxml/">source
Daniel Veillard306be992000-07-03 12:38:45 +0000[diff] [blame]506archive</a> or <a
Daniel Veillarda41123c2001-04-22 19:31:20 +0000[diff] [blame]507href="ftp://ftp.gnome.org/pub/GNOME/stable/redhat/i386/libxml/">RPM
508packages</a>. (NOTE that you need both the <a
Daniel Veillardc19fccc2000-07-03 11:52:01 +0000[diff] [blame]509href="http://rpmfind.net/linux/RPM/libxml2.html">libxml(2)</a> and <a
510href="http://rpmfind.net/linux/RPM/libxml2-devel.html">libxml(2)-devel</a>
Daniel Veillard95189532001-07-26 18:30:26 +0000[diff] [blame]511packages installed to compile applications using libxml.) <a
512href="mailto:izlatkovic@daenet.de">Igor Zlatkovic</a> is now the maintainer
513of the Windows port, <a
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]514href="http://www.fh-frankfurt.de/~igor/projects/libxml/index.html">he
Daniel Veillardc6271d22001-10-27 07:50:58 +0000[diff] [blame]515provides binaries</a>. <a href="mailto:Gary.Pennington@sun.com">Gary
516Pennington</a> provides <a
517href="http://pages.eidosnet.co.uk/~garypen/libxml/">Solaris binaries</a>.</p>
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]518
Daniel Veillard6c8b1172000-03-01 00:40:41 +0000[diff] [blame]519<p><a name="Snapshot">Snapshot:</a></p>
520<ul>
521 <li>Code from the W3C cvs base libxml <a
Daniel Veillard33a67802001-03-07 09:44:02 +0000[diff] [blame]522 href="ftp://xmlsoft.org/cvs-snapshot.tar.gz">cvs-snapshot.tar.gz</a></li>
Daniel Veillard6c8b1172000-03-01 00:40:41 +0000[diff] [blame]523 <li>Docs, content of the web site, the list archive included <a
Daniel Veillard33a67802001-03-07 09:44:02 +0000[diff] [blame]524 href="ftp://xmlsoft.org/libxml-docs.tar.gz">libxml-docs.tar.gz</a></li>
Daniel Veillard6c8b1172000-03-01 00:40:41 +0000[diff] [blame]525</ul>
526
Daniel Veillardc6271d22001-10-27 07:50:58 +0000[diff] [blame]527<p><a name="Contribs">Contributions:</a></p>
Daniel Veillard6c8b1172000-03-01 00:40:41 +0000[diff] [blame]528
529<p>I do accept external contributions, especially if compiling on another
Daniel Veillardc6271d22001-10-27 07:50:58 +0000[diff] [blame]530platform, get in touch with me to upload the package, wrappers for various
Daniel Veillard51095312001-10-28 18:51:57 +0000[diff] [blame]531languages have been provided, and can be found in the <a
532href="contribs.html">contrib section</a></p>
Daniel Veillard6c8b1172000-03-01 00:40:41 +0000[diff] [blame]533
Daniel Veillard82687162001-01-22 15:32:01 +0000[diff] [blame]534<p>Libxml is also available from CVS:</p>
Daniel Veillard10a2c651999-12-12 13:03:50 +0000[diff] [blame]535<ul>
Daniel Veillard10a2c651999-12-12 13:03:50 +0000[diff] [blame]536 <li><p>The <a
537 href="http://cvs.gnome.org/bonsai/rview.cgi?cvsroot=/cvs/gnome&amp;dir=gnome-xml">Gnome
Daniel Veillard402e8c82000-02-29 22:57:47 +0000[diff] [blame]538 CVS base</a>. Check the <a
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]539 href="http://developer.gnome.org/tools/cvs.html">Gnome CVS Tools</a>
540 page; the CVS module is <b>gnome-xml</b>.</p>
Daniel Veillard10a2c651999-12-12 13:03:50 +0000[diff] [blame]541 </li>
Daniel Veillard82687162001-01-22 15:32:01 +0000[diff] [blame]542 <li>The <strong>libxslt</strong> module is also present there</li>
Daniel Veillard10a2c651999-12-12 13:03:50 +0000[diff] [blame]543</ul>
544
545<h2><a name="News">News</a></h2>
546
Daniel Veillard944b5ff1999-12-15 19:08:24 +0000[diff] [blame]547<h3>CVS only : check the <a
548href="http://cvs.gnome.org/lxr/source/gnome-xml/ChangeLog">Changelog</a> file
Daniel Veillard189446d2000-10-13 10:23:06 +0000[diff] [blame]549for a really accurate description</h3>
Daniel Veillardab8500d2000-10-15 21:06:19 +0000[diff] [blame]550
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]551<p>Items floating around but not actively worked on, get in touch with me if
Daniel Veillardab8500d2000-10-15 21:06:19 +0000[diff] [blame]552you want to test those</p>
553<ul>
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]554 <li>Implementing <a href="http://xmlsoft.org/XSLT">XSLT</a>, this is done
555 as a separate C library on top of libxml called libxslt</li>
Daniel Veillard28929b22000-11-13 18:22:49 +0000[diff] [blame]556 <li>Finishing up <a href="http://www.w3.org/TR/xptr">XPointer</a> and <a
557 href="http://www.w3.org/TR/xinclude">XInclude</a></li>
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]558 <li>(seeems working but delayed from release) parsing/import of Docbook
559 SGML docs</li>
560</ul>
561
Daniel Veillarda4871052001-11-26 13:19:48 +0000[diff] [blame^]562<h3>2.4.11: Nov 26 2001</h3>
563<ul>
564 <li>fixed a couple of errors in the includes, fixed a few bugs, some code
565 cleanups</li>
566 <li>xmllint man pages improvement by Heiko Rupp</li>
567 <li>updated VMS build instructions from John A Fotheringham</li>
568 <li>Windows Makefiles updates from Igor</li>
569</ul>
570
Daniel Veillard43d3f612001-11-10 11:57:23 +0000[diff] [blame]571<h3>2.4.10: Nov 10 2001</h3>
572<ul>
573 <li>URI escaping fix (Joel Young)</li>
574 <li>added xmlGetNodePath() (for paths or XPointers generation)</li>
575 <li>Fixes namespace handling problems when using DTD and validation</li>
576 <li>improvements on xmllint: Morus Walter patches for --format and
577 --encode, Stefan Kost and Heiko Rupp improvements on the --shell</li>
578 <li>fixes for xmlcatalog linking pointed by Weiqi Gao</li>
579 <li>fixes to the HTML parser</li>
580</ul>
581
582<h3>2.4.9: Nov 6 2001</h3>
583<ul>
584 <li>fixes more catalog bugs</li>
585 <li>avoid a compilation problem, improve xmlGetLineNo()</li>
586</ul>
587
Daniel Veillarded421aa2001-11-04 21:22:45 +0000[diff] [blame]588<h3>2.4.8: Nov 4 2001</h3>
589<ul>
590 <li>fixed SGML catalogs broken in previous release, updated xmlcatalog
591 tool</li>
592 <li>fixed a compile errors and some includes troubles.</li>
593</ul>
594
Daniel Veillard52dcab32001-10-30 12:51:17 +0000[diff] [blame]595<h3>2.4.7: Oct 30 2001</h3>
596<ul>
597 <li>exported some debugging interfaces</li>
598 <li>serious rewrite of the catalog code</li>
599 <li>integrated Gary Pennington thread safety patch, added configure option
600 and regression tests</li>
601 <li>removed an HTML parser bug</li>
602 <li>fixed a couple of potentially serious validation bugs</li>
603 <li>integrated the SGML DocBook support in xmllint</li>
604 <li>changed the nanoftp anonymous login passwd</li>
605 <li>some I/O cleanup and a couple of interfaces for Perl wrapper</li>
606 <li>general bug fixes</li>
607 <li>updated xmllint man page by John Fleck</li>
608 <li>some VMS and Windows updates</li>
609</ul>
610
Daniel Veillard60087f32001-10-10 09:45:09 +0000[diff] [blame]611<h3>2.4.6: Oct 10 2001</h3>
612<ul>
Daniel Veillard52dcab32001-10-30 12:51:17 +0000[diff] [blame]613 <li>added an updated man pages by John Fleck</li>
Daniel Veillard60087f32001-10-10 09:45:09 +0000[diff] [blame]614 <li>portability and configure fixes</li>
615 <li>an infinite loop on the HTML parser was removed (William)</li>
616 <li>Windows makefile patches from Igor</li>
617 <li>fixed half a dozen bugs reported fof libxml or libxslt</li>
618 <li>updated xmlcatalog to be able to modify SGML super catalogs</li>
619</ul>
620
Daniel Veillarddadd0872001-09-15 09:21:44 +0000[diff] [blame]621<h3>2.4.5: Sep 14 2001</h3>
622<ul>
623 <li>Remove a few annoying bugs in 2.4.4</li>
624 <li>forces the HTML serializer to output decimal charrefs since some
625 version of Netscape can't handle hexadecimal ones</li>
626</ul>
627
628<h3>1.8.16: Sep 14 2001</h3>
629<ul>
630 <li>maintenance release of the old libxml1 branch, couple of bug and
631 portability fixes</li>
632</ul>
633
Daniel Veillard04382ae2001-09-12 18:51:30 +0000[diff] [blame]634<h3>2.4.4: Sep 12 2001</h3>
635<ul>
636 <li>added --convert to xmlcatalog, bug fixes and cleanups of XML
637 Catalog</li>
638 <li>a few bug fixes and some portability changes</li>
639 <li>some documentation cleanups</li>
640</ul>
641
Daniel Veillard39936902001-08-24 00:49:01 +0000[diff] [blame]642<h3>2.4.3: Aug 23 2001</h3>
643<ul>
644 <li>XML Catalog support see the doc</li>
645 <li>New NaN/Infinity floating point code</li>
646 <li>A few bug fixes</li>
647</ul>
648
649<h3>2.4.2: Aug 15 2001</h3>
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]650<ul>
651 <li>adds xmlLineNumbersDefault() to control line number generation</li>
652 <li>lot of bug fixes</li>
653 <li>the Microsoft MSC projects files shuld now be up to date</li>
654 <li>inheritance of namespaces from DTD defaulted attributes</li>
655 <li>fixes a serious potential security bug</li>
656 <li>added a --format option to xmllint</li>
657</ul>
658
659<h3>2.4.1: July 24 2001</h3>
660<ul>
661 <li>possibility to keep line numbers in the tree</li>
662 <li>some computation NaN fixes</li>
663 <li>extension of the XPath API</li>
664 <li>cleanup for alpha and ia64 targets</li>
665 <li>patch to allow saving through HTTP PUT or POST</li>
Daniel Veillard09ab7e12001-07-10 15:49:44 +0000[diff] [blame]666</ul>
667
668<h3>2.4.0: July 10 2001</h3>
669<ul>
670 <li>Fixed a few bugs in XPath, validation, and tree handling.</li>
671 <li>Fixed XML Base implementation, added a coupel of examples to the
672 regression tests</li>
673 <li>A bit of cleanup</li>
Daniel Veillardab8500d2000-10-15 21:06:19 +0000[diff] [blame]674</ul>
675
Daniel Veillard5b43fde2001-07-05 23:31:40 +0000[diff] [blame]676<h3>2.3.14: July 5 2001</h3>
677<ul>
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]678 <li>fixed some entities problems and reduce mem requirement when
679 substituing them</li>
Daniel Veillard5b43fde2001-07-05 23:31:40 +0000[diff] [blame]680 <li>lots of improvements in the XPath queries interpreter can be
681 substancially faster</li>
682 <li>Makefiles and configure cleanups</li>
683 <li>Fixes to XPath variable eval, and compare on empty node set</li>
684 <li>HTML tag closing bug fixed</li>
685 <li>Fixed an URI reference computating problem when validating</li>
686</ul>
687
Daniel Veillard2adbb512001-06-28 16:20:36 +0000[diff] [blame]688<h3>2.3.13: June 28 2001</h3>
689<ul>
690 <li>2.3.12 configure.in was broken as well as the push mode XML parser</li>
691 <li>a few more fixes for compilation on Windows MSC by Yon Derek</li>
692</ul>
693
694<h3>1.8.14: June 28 2001</h3>
695<ul>
696 <li>Zbigniew Chyla gave a patch to use the old XML parser in push mode</li>
697 <li>Small Makefile fix</li>
698</ul>
699
Daniel Veillard11648102001-06-26 16:08:24 +0000[diff] [blame]700<h3>2.3.12: June 26 2001</h3>
701<ul>
702 <li>lots of cleanup</li>
703 <li>a couple of validation fix</li>
704 <li>fixed line number counting</li>
705 <li>fixed serious problems in the XInclude processing</li>
706 <li>added support for UTF8 BOM at beginning of entities</li>
707 <li>fixed a strange gcc optimizer bugs in xpath handling of float, gcc-3.0
708 miscompile uri.c (William), Thomas Leitner provided a fix for the
709 optimizer on Tru64</li>
710 <li>incorporated Yon Derek and Igor Zlatkovic fixes and improvements for
711 compilation on Windows MSC</li>
712 <li>update of libxml-doc.el (Felix Natter)</li>
713 <li>fixed 2 bugs in URI normalization code</li>
714</ul>
715
Daniel Veillarde3c81b52001-06-17 14:50:34 +0000[diff] [blame]716<h3>2.3.11: June 17 2001</h3>
717<ul>
718 <li>updates to trio, Makefiles and configure should fix some portability
719 problems (alpha)</li>
720 <li>fixed some HTML serialization problems (pre, script, and block/inline
721 handling), added encoding aware APIs, cleanup of this code</li>
722 <li>added xmlHasNsProp()</li>
723 <li>implemented a specific PI for encoding support in the DocBook SGML
724 parser</li>
725 <li>some XPath fixes (-Infinity, / as a function parameter and namespaces
726 node selection)</li>
727 <li>fixed a performance problem and an error in the validation code</li>
728 <li>fixed XInclude routine to implement the recursive behaviour</li>
729 <li>fixed xmlFreeNode problem when libxml is included statically twice</li>
730 <li>added --version to xmllint for bug reports</li>
731</ul>
732
Daniel Veillard2e4f1882001-06-01 10:11:57 +0000[diff] [blame]733<h3>2.3.10: June 1 2001</h3>
734<ul>
735 <li>fixed the SGML catalog support</li>
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]736 <li>a number of reported bugs got fixed, in XPath, iconv detection,
737 XInclude processing</li>
Daniel Veillard2e4f1882001-06-01 10:11:57 +0000[diff] [blame]738 <li>XPath string function should now handle unicode correctly</li>
739</ul>
740
Daniel Veillard4623acd2001-05-19 15:13:15 +0000[diff] [blame]741<h3>2.3.9: May 19 2001</h3>
742
743<p>Lots of bugfixes, and added a basic SGML catalog support:</p>
744<ul>
745 <li>HTML push bugfix #54891 and another patch from Jonas Borgström</li>
746 <li>some serious speed optimisation again</li>
747 <li>some documentation cleanups</li>
748 <li>trying to get better linking on solaris (-R)</li>
749 <li>XPath API cleanup from Thomas Broyer</li>
750 <li>Validation bug fixed #54631, added a patch from Gary Pennington, fixed
751 xmlValidGetValidElements()</li>
752 <li>Added an INSTALL file</li>
753 <li>Attribute removal added to API: #54433</li>
754 <li>added a basic support for SGML catalogs</li>
755 <li>fixed xmlKeepBlanksDefault(0) API</li>
756 <li>bugfix in xmlNodeGetLang()</li>
757 <li>fixed a small configure portability problem</li>
758 <li>fixed an inversion of SYSTEM and PUBLIC identifier in HTML document</li>
759</ul>
760
Daniel Veillarda265af72001-05-14 11:13:58 +0000[diff] [blame]761<h3>1.8.13: May 14 2001</h3>
762<ul>
763 <li>bugfixes release of the old libxml1 branch used by Gnome</li>
764</ul>
765
Daniel Veillard3bbbe6f2001-05-03 11:15:37 +0000[diff] [blame]766<h3>2.3.8: May 3 2001</h3>
767<ul>
768 <li>Integrated an SGML DocBook parser for the Gnome project</li>
769 <li>Fixed a few things in the HTML parser</li>
770 <li>Fixed some XPath bugs raised by XSLT use, tried to fix the floating
771 point portability issue</li>
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]772 <li>Speed improvement (8M/s for SAX, 3M/s for DOM, 1.5M/s for
773 DOM+validation using the XML REC as input and a 700MHz celeron).</li>
Daniel Veillard3bbbe6f2001-05-03 11:15:37 +0000[diff] [blame]774 <li>incorporated more Windows cleanup</li>
775 <li>added xmlSaveFormatFile()</li>
776 <li>fixed problems in copying nodes with entities references (gdome)</li>
777 <li>removed some troubles surrounding the new validation module</li>
778</ul>
779
Daniel Veillarda41123c2001-04-22 19:31:20 +0000[diff] [blame]780<h3>2.3.7: April 22 2001</h3>
781<ul>
782 <li>lots of small bug fixes, corrected XPointer</li>
783 <li>Non determinist content model validation support</li>
784 <li>added xmlDocCopyNode for gdome2</li>
785 <li>revamped the way the HTML parser handles end of tags</li>
786 <li>XPath: corrctions of namespacessupport and number formatting</li>
787 <li>Windows: Igor Zlatkovic patches for MSC compilation</li>
788 <li>HTML ouput fixes from P C Chow and William M. Brack</li>
789 <li>Improved validation speed sensible for DocBook</li>
790 <li>fixed a big bug with ID declared in external parsed entities</li>
791 <li>portability fixes, update of Trio from Bjorn Reese</li>
792</ul>
793
Daniel Veillardafc73112001-04-11 11:51:41 +0000[diff] [blame]794<h3>2.3.6: April 8 2001</h3>
795<ul>
796 <li>Code cleanup using extreme gcc compiler warning options, found and
797 cleared half a dozen potential problem</li>
798 <li>the Eazel team found an XML parser bug</li>
799 <li>cleaned up the user of some of the string formatting function. used the
800 trio library code to provide the one needed when the platform is missing
801 them</li>
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]802 <li>xpath: removed a memory leak and fixed the predicate evaluation
803 problem, extended the testsuite and cleaned up the result. XPointer seems
804 broken ...</li>
Daniel Veillardafc73112001-04-11 11:51:41 +0000[diff] [blame]805</ul>
806
Daniel Veillard56a4cb82001-03-24 17:00:36 +0000[diff] [blame]807<h3>2.3.5: Mar 23 2001</h3>
808<ul>
809 <li>Biggest change is separate parsing and evaluation of XPath expressions,
810 there is some new APIs for this too</li>
811 <li>included a number of bug fixes(XML push parser, 51876, notations,
812 52299)</li>
813 <li>Fixed some portability issues</li>
814</ul>
815
Daniel Veillarde356c282001-03-10 12:32:04 +0000[diff] [blame]816<h3>2.3.4: Mar 10 2001</h3>
817<ul>
818 <li>Fixed bugs #51860 and #51861</li>
819 <li>Added a global variable xmlDefaultBufferSize to allow default buffer
820 size to be application tunable.</li>
821 <li>Some cleanup in the validation code, still a bug left and this part
822 should probably be rewritten to support ambiguous content model :-\</li>
823 <li>Fix a couple of serious bugs introduced or raised by changes in 2.3.3
824 parser</li>
825 <li>Fixed another bug in xmlNodeGetContent()</li>
826 <li>Bjorn fixed XPath node collection and Number formatting</li>
827 <li>Fixed a loop reported in the HTML parsing</li>
828 <li>blank space are reported even if the Dtd content model proves that they
829 are formatting spaces, this is for XmL conformance</li>
830</ul>
831
Daniel Veillardb402c072001-03-01 17:28:58 +0000[diff] [blame]832<h3>2.3.3: Mar 1 2001</h3>
833<ul>
834 <li>small change in XPath for XSLT</li>
835 <li>documentation cleanups</li>
836 <li>fix in validation by Gary Pennington</li>
837 <li>serious parsing performances improvements</li>
838</ul>
839
Daniel Veillardec70e912001-02-26 20:10:45 +0000[diff] [blame]840<h3>2.3.2: Feb 24 2001</h3>
Daniel Veillard71681102001-02-24 17:48:53 +0000[diff] [blame]841<ul>
842 <li>chasing XPath bugs, found a bunch, completed some TODO</li>
843 <li>fixed a Dtd parsing bug</li>
844 <li>fixed a bug in xmlNodeGetContent</li>
845 <li>ID/IDREF support partly rewritten by Gary Pennington</li>
846</ul>
847
Daniel Veillardec70e912001-02-26 20:10:45 +0000[diff] [blame]848<h3>2.3.1: Feb 15 2001</h3>
Daniel Veillard6e6a6cc2001-02-15 15:55:44 +0000[diff] [blame]849<ul>
850 <li>some XPath and HTML bug fixes for XSLT</li>
851 <li>small extension of the hash table interfaces for DOM gdome2
852 implementation</li>
853 <li>A few bug fixes</li>
854</ul>
855
Daniel Veillardec70e912001-02-26 20:10:45 +0000[diff] [blame]856<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]857<ul>
858 <li>Lots of XPath bug fixes</li>
859 <li>Add a mode with Dtd lookup but without validation error reporting for
860 XSLT</li>
861 <li>Add support for text node without escaping (XSLT)</li>
862 <li>bug fixes for xmlCheckFilename</li>
863 <li>validation code bug fixes from Gary Pennington</li>
864 <li>Patch from Paul D. Smith correcting URI path normalization</li>
865 <li>Patch to allow simultaneous install of libxml-devel and
866 libxml2-devel</li>
867 <li>the example Makefile is now fixed</li>
868 <li>added HTML to the RPM packages</li>
869 <li>tree copying bugfixes</li>
870 <li>updates to Windows makefiles</li>
871 <li>optimisation patch from Bjorn Reese</li>
872</ul>
873
Daniel Veillardec70e912001-02-26 20:10:45 +0000[diff] [blame]874<h3>2.2.11: Jan 4 2001</h3>
Daniel Veillard503b8932001-01-05 06:36:31 +0000[diff] [blame]875<ul>
876 <li>bunch of bug fixes (memory I/O, xpath, ftp/http, ...)</li>
877 <li>added htmlHandleOmittedElem()</li>
878 <li>Applied Bjorn Reese's IPV6 first patch</li>
879 <li>Applied Paul D. Smith patches for validation of XInclude results</li>
Daniel Veillard82687162001-01-22 15:32:01 +0000[diff] [blame]880 <li>added XPointer xmlns() new scheme support</li>
Daniel Veillard503b8932001-01-05 06:36:31 +0000[diff] [blame]881</ul>
882
Daniel Veillard2ddd23d2000-11-25 10:42:19 +0000[diff] [blame]883<h3>2.2.10: Nov 25 2000</h3>
Daniel Veillard9d343c42000-11-25 10:12:43 +0000[diff] [blame]884<ul>
885 <li>Fix the Windows problems of 2.2.8</li>
886 <li>integrate OpenVMS patches</li>
887 <li>better handling of some nasty HTML input</li>
888 <li>Improved the XPointer implementation</li>
889 <li>integrate a number of provided patches</li>
890</ul>
891
Daniel Veillard2ddd23d2000-11-25 10:42:19 +0000[diff] [blame]892<h3>2.2.9: Nov 25 2000</h3>
893<ul>
894 <li>erroneous release :-(</li>
895</ul>
896
Daniel Veillard28929b22000-11-13 18:22:49 +0000[diff] [blame]897<h3>2.2.8: Nov 13 2000</h3>
898<ul>
899 <li>First version of <a href="http://www.w3.org/TR/xinclude">XInclude</a>
900 support</li>
901 <li>Patch in conditional section handling</li>
902 <li>updated MS compiler project</li>
903 <li>fixed some XPath problems</li>
904 <li>added an URI escaping function</li>
905 <li>some other bug fixes</li>
906</ul>
907
908<h3>2.2.7: Oct 31 2000</h3>
909<ul>
910 <li>added message redirection</li>
911 <li>XPath improvements (thanks TOM !)</li>
912 <li>xmlIOParseDTD() added</li>
913 <li>various small fixes in the HTML, URI, HTTP and XPointer support</li>
914 <li>some cleanup of the Makefile, autoconf and the distribution content</li>
915</ul>
916
Daniel Veillard29a11cc2000-10-25 13:32:39 +0000[diff] [blame]917<h3>2.2.6: Oct 25 2000:</h3>
918<ul>
919 <li>Added an hash table module, migrated a number of internal structure to
920 those</li>
921 <li>Fixed a posteriori validation problems</li>
922 <li>HTTP module cleanups</li>
923 <li>HTML parser improvements (tag errors, script/style handling, attribute
924 normalization)</li>
925 <li>coalescing of adjacent text nodes</li>
926 <li>couple of XPath bug fixes, exported the internal API</li>
927</ul>
928
Daniel Veillardab8500d2000-10-15 21:06:19 +0000[diff] [blame]929<h3>2.2.5: Oct 15 2000:</h3>
Daniel Veillard4c3a2031999-11-19 17:46:26 +0000[diff] [blame]930<ul>
Daniel Veillard189446d2000-10-13 10:23:06 +0000[diff] [blame]931 <li>XPointer implementation and testsuite</li>
932 <li>Lot of XPath fixes, added variable and functions registration, more
933 tests</li>
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]934 <li>Portability fixes, lots of enhancements toward an easy Windows build
935 and release</li>
Daniel Veillard189446d2000-10-13 10:23:06 +0000[diff] [blame]936 <li>Late validation fixes</li>
937 <li>Integrated a lot of contributed patches</li>
938 <li>added memory management docs</li>
Daniel Veillardab8500d2000-10-15 21:06:19 +0000[diff] [blame]939 <li>a performance problem when using large buffer seems fixed</li>
Daniel Veillard189446d2000-10-13 10:23:06 +0000[diff] [blame]940</ul>
941
942<h3>2.2.4: Oct 1 2000:</h3>
943<ul>
944 <li>main XPath problem fixed</li>
945 <li>Integrated portability patches for Windows</li>
946 <li>Serious bug fixes on the URI and HTML code</li>
Daniel Veillard361d8452000-04-03 19:48:13 +0000[diff] [blame]947</ul>
948
Daniel Veillardd5f97f82000-09-17 16:38:14 +0000[diff] [blame]949<h3>2.2.3: Sep 17 2000</h3>
950<ul>
951 <li>bug fixes</li>
952 <li>cleanup of entity handling code</li>
953 <li>overall review of all loops in the parsers, all sprintf usage has been
954 checked too</li>
955 <li>Far better handling of larges Dtd. Validating against Docbook XML Dtd
956 works smoothly now.</li>
957</ul>
958
959<h3>1.8.10: Sep 6 2000</h3>
960<ul>
961 <li>bug fix release for some Gnome projects</li>
962</ul>
963
964<h3>2.2.2: August 12 2000</h3>
Daniel Veillard786d7c82000-08-12 23:38:57 +0000[diff] [blame]965<ul>
966 <li>mostly bug fixes</li>
Daniel Veillardec78c0f2000-08-25 10:25:23 +0000[diff] [blame]967 <li>started adding routines to access xml parser context options</li>
Daniel Veillard786d7c82000-08-12 23:38:57 +0000[diff] [blame]968</ul>
969
Daniel Veillardd5f97f82000-09-17 16:38:14 +0000[diff] [blame]970<h3>2.2.1: July 21 2000</h3>
Daniel Veillarda2679fa2000-07-22 02:38:15 +0000[diff] [blame]971<ul>
972 <li>a purely bug fixes release</li>
973 <li>fixed an encoding support problem when parsing from a memory block</li>
974 <li>fixed a DOCTYPE parsing problem</li>
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]975 <li>removed a bug in the function allowing to override the memory
976 allocation routines</li>
Daniel Veillarda2679fa2000-07-22 02:38:15 +0000[diff] [blame]977</ul>
978
Daniel Veillardd5f97f82000-09-17 16:38:14 +0000[diff] [blame]979<h3>2.2.0: July 14 2000</h3>
Daniel Veillard94e90602000-07-17 14:38:19 +0000[diff] [blame]980<ul>
981 <li>applied a lot of portability fixes</li>
982 <li>better encoding support/cleanup and saving (content is now always
983 encoded in UTF-8)</li>
984 <li>the HTML parser now correctly handles encodings</li>
985 <li>added xmlHasProp()</li>
986 <li>fixed a serious problem with &amp;#38;</li>
987 <li>propagated the fix to FTP client</li>
988 <li>cleanup, bugfixes, etc ...</li>
989 <li>Added a page about <a href="encoding.html">libxml Internationalization
990 support</a></li>
991</ul>
992
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]993<h3>1.8.9: July 9 2000</h3>
994<ul>
995 <li>fixed the spec the RPMs should be better</li>
996 <li>fixed a serious bug in the FTP implementation, released 1.8.9 to solve
997 rpmfind users problem</li>
998</ul>
999
Daniel Veillard6388e172000-07-03 16:07:19 +0000[diff] [blame]1000<h3>2.1.1: July 1 2000</h3>
1001<ul>
1002 <li>fixes a couple of bugs in the 2.1.0 packaging</li>
1003 <li>improvements on the HTML parser</li>
1004</ul>
1005
Daniel Veillard3f6f7f62000-06-30 17:58:25 +0000[diff] [blame]1006<h3>2.1.0 and 1.8.8: June 29 2000</h3>
1007<ul>
1008 <li>1.8.8 is mostly a comodity package for upgrading to libxml2 accoding to
1009 <a href="upgrade.html">new instructions</a>. It fixes a nasty problem
1010 about &amp;#38; charref parsing</li>
1011 <li>2.1.0 also ease the upgrade from libxml v1 to the recent version. it
1012 also contains numerous fixes and enhancements:
1013 <ul>
1014 <li>added xmlStopParser() to stop parsing</li>
1015 <li>improved a lot parsing speed when there is large CDATA blocs</li>
1016 <li>includes XPath patches provided by Picdar Technology</li>
1017 <li>tried to fix as much as possible DtD validation and namespace
1018 related problems</li>
1019 <li>output to a given encoding has been added/tested</li>
1020 <li>lot of various fixes</li>
1021 </ul>
1022 </li>
1023</ul>
1024
Daniel Veillarde0aed302000-04-16 08:52:20 +0000[diff] [blame]1025<h3>2.0.0: Apr 12 2000</h3>
Daniel Veillard361d8452000-04-03 19:48:13 +0000[diff] [blame]1026<ul>
1027 <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]1028 idea to check the 1.x to 2.x upgrade instructions. NOTE: while initally
1029 scheduled for Apr 3 the relase occured only on Apr 12 due to massive
1030 workload.</li>
Daniel Veillard361d8452000-04-03 19:48:13 +0000[diff] [blame]1031 <li>The include are now located under $prefix/include/libxml (instead of
Daniel Veillarde0aed302000-04-16 08:52:20 +0000[diff] [blame]1032 $prefix/include/gnome-xml), they also are referenced by
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]1033 <pre>#include &lt;libxml/xxx.h&gt;</pre>
Daniel Veillarde0aed302000-04-16 08:52:20 +0000[diff] [blame]1034 <p>instead of</p>
Daniel Veillard361d8452000-04-03 19:48:13 +0000[diff] [blame]1035 <pre>#include "xxx.h"</pre>
1036 </li>
Daniel Veillard8f621982000-03-20 13:07:15 +0000[diff] [blame]1037 <li>a new URI module for parsing URIs and following strictly RFC 2396</li>
1038 <li>the memory allocation routines used by libxml can now be overloaded
1039 dynamically by using xmlMemSetup()</li>
Daniel Veillard361d8452000-04-03 19:48:13 +0000[diff] [blame]1040 <li>The previously CVS only tool tester has been renamed
1041 <strong>xmllint</strong> and is now installed as part of the libxml2
1042 package</li>
Daniel Veillarde0aed302000-04-16 08:52:20 +0000[diff] [blame]1043 <li>The I/O interface has been revamped. There is now ways to plug in
1044 specific I/O modules, either at the URI scheme detection level using
1045 xmlRegisterInputCallbacks() or by passing I/O functions when creating a
1046 parser context using xmlCreateIOParserCtxt()</li>
1047 <li>there is a C preprocessor macro LIBXML_VERSION providing the version
1048 number of the libxml module in use</li>
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]1049 <li>a number of optional features of libxml can now be excluded at
1050 configure time (FTP/HTTP/HTML/XPath/Debug)</li>
Daniel Veillardedfb29b2000-03-14 19:59:05 +0000[diff] [blame]1051</ul>
1052
1053<h3>2.0.0beta: Mar 14 2000</h3>
1054<ul>
1055 <li>This is a first Beta release of libxml version 2</li>
Daniel Veillarde356c282001-03-10 12:32:04 +0000[diff] [blame]1056 <li>It's available only from<a href="ftp://xmlsoft.org/">xmlsoft.org
1057 FTP</a>, it's packaged as libxml2-2.0.0beta and available as tar and
1058 RPMs</li>
Daniel Veillardedfb29b2000-03-14 19:59:05 +0000[diff] [blame]1059 <li>This version is now the head in the Gnome CVS base, the old one is
1060 available under the tag LIB_XML_1_X</li>
1061 <li>This includes a very large set of changes. Froma programmatic point of
1062 view applications should not have to be modified too much, check the <a
1063 href="upgrade.html">upgrade page</a></li>
1064 <li>Some interfaces may changes (especially a bit about encoding).</li>
1065 <li>the updates includes:
Daniel Veillard6c8b1172000-03-01 00:40:41 +0000[diff] [blame]1066 <ul>
Daniel Veillardedfb29b2000-03-14 19:59:05 +0000[diff] [blame]1067 <li>fix I18N support. ISO-Latin-x/UTF-8/UTF-16 (nearly) seems correctly
1068 handled now</li>
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]1069 <li>Better handling of entities, especially well formedness checking
1070 and proper PEref extensions in external subsets</li>
Daniel Veillard6c8b1172000-03-01 00:40:41 +0000[diff] [blame]1071 <li>DTD conditional sections</li>
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]1072 <li>Validation now correcly handle entities content</li>
Daniel Veillard6c8b1172000-03-01 00:40:41 +0000[diff] [blame]1073 <li><a href="http://rpmfind.net/tools/gdome/messages/0039.html">change
1074 structures to accomodate DOM</a></li>
Daniel Veillard6c8b1172000-03-01 00:40:41 +0000[diff] [blame]1075 </ul>
1076 </li>
Daniel Veillardedfb29b2000-03-14 19:59:05 +0000[diff] [blame]1077 <li>Serious progress were made toward compliance, <a
1078 href="conf/result.html">here are the result of the test</a> against the
1079 OASIS testsuite (except the japanese tests since I don't support that
1080 encoding yet). This URL is rebuilt every couple of hours using the CVS
1081 head version.</li>
Daniel Veillarde41f2b72000-01-30 20:00:07 +0000[diff] [blame]1082</ul>
1083
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]1084<h3>1.8.7: Mar 6 2000</h3>
1085<ul>
1086 <li>This is a bug fix release:</li>
1087 <li>It is possible to disable the ignorable blanks heuristic used by
1088 libxml-1.x, a new function xmlKeepBlanksDefault(0) will allow this. Note
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]1089 that for adherence to XML spec, this behaviour will be disabled by
1090 default in 2.x . The same function will allow to keep compatibility for
1091 old code.</li>
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]1092 <li>Blanks in &lt;a&gt; &lt;/a&gt; constructs are not ignored anymore,
1093 avoiding heuristic is really the Right Way :-\</li>
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]1094 <li>The unchecked use of snprintf which was breaking libxml-1.8.6
1095 compilation on some platforms has been fixed</li>
1096 <li>nanoftp.c nanohttp.c: Fixed '#' and '?' stripping when processing
1097 URIs</li>
1098</ul>
1099
Daniel Veillarde41f2b72000-01-30 20:00:07 +0000[diff] [blame]1100<h3>1.8.6: Jan 31 2000</h3>
1101<ul>
1102 <li>added a nanoFTP transport module, debugged until the new version of <a
1103 href="http://rpmfind.net/linux/rpm2html/rpmfind.html">rpmfind</a> can use
1104 it without troubles</li>
Daniel Veillardda07c342000-01-25 18:31:22 +0000[diff] [blame]1105</ul>
1106
1107<h3>1.8.5: Jan 21 2000</h3>
1108<ul>
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]1109 <li>adding APIs to parse a well balanced chunk of XML (production <a
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]1110 href="http://www.w3.org/TR/REC-xml#NT-content">[43] content</a> of the
1111 XML spec)</li>
Daniel Veillard461a66c2000-01-18 18:01:01 +0000[diff] [blame]1112 <li>fixed a hideous bug in xmlGetProp pointed by Rune.Djurhuus@fast.no</li>
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]1113 <li>Jody Goldberg &lt;jgoldberg@home.com&gt; provided another patch trying
1114 to solve the zlib checks problems</li>
Daniel Veillard461a66c2000-01-18 18:01:01 +0000[diff] [blame]1115 <li>The current state in gnome CVS base is expected to ship as 1.8.5 with
1116 gnumeric soon</li>
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]1117</ul>
1118
1119<h3>1.8.4: Jan 13 2000</h3>
1120<ul>
1121 <li>bug fixes, reintroduced xmlNewGlobalNs(), fixed xmlNewNs()</li>
1122 <li>all exit() call should have been removed from libxml</li>
1123 <li>fixed a problem with INCLUDE_WINSOCK on WIN32 platform</li>
1124 <li>added newDocFragment()</li>
Daniel Veillardf84f71f2000-01-05 19:54:23 +0000[diff] [blame]1125</ul>
1126
1127<h3>1.8.3: Jan 5 2000</h3>
1128<ul>
1129 <li>a Push interface for the XML and HTML parsers</li>
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]1130 <li>a shell-like interface to the document tree (try tester --shell :-)</li>
Daniel Veillarddbfd6411999-12-28 16:35:14 +0000[diff] [blame]1131 <li>lots of bug fixes and improvement added over XMas hollidays</li>
Daniel Veillard437b87b2000-01-03 17:30:46 +0000[diff] [blame]1132 <li>fixed the DTD parsing code to work with the xhtml DTD</li>
Daniel Veillardf84f71f2000-01-05 19:54:23 +0000[diff] [blame]1133 <li>added xmlRemoveProp(), xmlRemoveID() and xmlRemoveRef()</li>
1134 <li>Fixed bugs in xmlNewNs()</li>
Daniel Veillard437b87b2000-01-03 17:30:46 +0000[diff] [blame]1135 <li>External entity loading code has been revamped, now it uses
Daniel Veillardf84f71f2000-01-05 19:54:23 +0000[diff] [blame]1136 xmlLoadExternalEntity(), some fix on entities processing were added</li>
Daniel Veillard437b87b2000-01-03 17:30:46 +0000[diff] [blame]1137 <li>cleaned up WIN32 includes of socket stuff</li>
Daniel Veillard5cb5ab81999-12-21 15:35:29 +0000[diff] [blame]1138</ul>
1139
1140<h3>1.8.2: Dec 21 1999</h3>
1141<ul>
Daniel Veillardb24054a1999-12-18 15:32:46 +0000[diff] [blame]1142 <li>I got another problem with includes and C++, I hope this issue is fixed
1143 for good this time</li>
Daniel Veillard5cb5ab81999-12-21 15:35:29 +0000[diff] [blame]1144 <li>Added a few tree modification functions: xmlReplaceNode,
1145 xmlAddPrevSibling, xmlAddNextSibling, xmlNodeSetName and
1146 xmlDocSetRootElement</li>
1147 <li>Tried to improve the HTML output with help from <a
1148 href="mailto:clahey@umich.edu">Chris Lahey</a></li>
Daniel Veillarde4e51311999-12-18 15:32:46 +0000[diff] [blame]1149</ul>
Daniel Veillardb24054a1999-12-18 15:32:46 +0000[diff] [blame]1150
Daniel Veillarde4e51311999-12-18 15:32:46 +0000[diff] [blame]1151<h3>1.8.1: Dec 18 1999</h3>
1152<ul>
1153 <li>various patches to avoid troubles when using libxml with C++ compilers
1154 the "namespace" keyword and C escaping in include files</li>
1155 <li>a problem in one of the core macros IS_CHAR was corrected</li>
1156 <li>fixed a bug introduced in 1.8.0 breaking default namespace processing,
1157 and more specifically the Dia application</li>
Daniel Veillard944b5ff1999-12-15 19:08:24 +0000[diff] [blame]1158 <li>fixed a posteriori validation (validation after parsing, or by using a
1159 Dtd not specified in the original document)</li>
Daniel Veillardb24054a1999-12-18 15:32:46 +0000[diff] [blame]1160 <li>fixed a bug in</li>
Daniel Veillard10a2c651999-12-12 13:03:50 +0000[diff] [blame]1161</ul>
1162
1163<h3>1.8.0: Dec 12 1999</h3>
1164<ul>
1165 <li>cleanup, especially memory wise</li>
1166 <li>the parser should be more reliable, especially the HTML one, it should
1167 not crash, whatever the input !</li>
1168 <li>Integrated various patches, especially a speedup improvement for large
1169 dataset from <a href="mailto:cnygard@bellatlantic.net">Carl Nygard</a>,
1170 configure with --with-buffers to enable them.</li>
1171 <li>attribute normalization, oops should have been added long ago !</li>
1172 <li>attributes defaulted from Dtds should be available, xmlSetProp() now
1173 does entities escapting by default.</li>
Daniel Veillard4c3a2031999-11-19 17:46:26 +0000[diff] [blame]1174</ul>
Daniel Veillard35008381999-10-25 13:15:52 +0000[diff] [blame]1175
1176<h3>1.7.4: Oct 25 1999</h3>
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]1177<ul>
Daniel Veillard35008381999-10-25 13:15:52 +0000[diff] [blame]1178 <li>Lots of HTML improvement</li>
1179 <li>Fixed some errors when saving both XML and HTML</li>
1180 <li>More examples, the regression tests should now look clean</li>
1181 <li>Fixed a bug with contiguous charref</li>
1182</ul>
1183
1184<h3>1.7.3: Sep 29 1999</h3>
1185<ul>
1186 <li>portability problems fixed</li>
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]1187 <li>snprintf was used unconditionnally, leading to link problems on system
Daniel Veillard35008381999-10-25 13:15:52 +0000[diff] [blame]1188 were it's not available, fixed</li>
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]1189</ul>
1190
1191<h3>1.7.1: Sep 24 1999</h3>
1192<ul>
1193 <li>The basic type for strings manipulated by libxml has been renamed in
1194 1.7.1 from <strong>CHAR</strong> to <strong>xmlChar</strong>. The reason
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]1195 is that CHAR was conflicting with a predefined type on Windows. However
1196 on non WIN32 environment, compatibility is provided by the way of a
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]1197 <strong>#define </strong>.</li>
1198 <li>Changed another error : the use of a structure field called errno, and
1199 leading to troubles on platforms where it's a macro</li>
1200</ul>
1201
1202<h3>1.7.0: sep 23 1999</h3>
1203<ul>
1204 <li>Added the ability to fetch remote DTD or parsed entities, see the <a
Daniel Veillard9cb5ff42001-01-29 08:22:21 +0000[diff] [blame]1205 href="html/libxml-nanohttp.html">nanohttp</a> module.</li>
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]1206 <li>Added an errno to report errors by another mean than a simple printf
1207 like callback</li>
1208 <li>Finished ID/IDREF support and checking when validation</li>
1209 <li>Serious memory leaks fixed (there is now a <a
Daniel Veillard9cb5ff42001-01-29 08:22:21 +0000[diff] [blame]1210 href="html/libxml-xmlmemory.html">memory wrapper</a> module)</li>
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]1211 <li>Improvement of <a href="http://www.w3.org/TR/xpath">XPath</a>
1212 implementation</li>
1213 <li>Added an HTML parser front-end</li>
1214</ul>
1215
1216<h2><a name="XML">XML</a></h2>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]1217
Daniel Veillard402e8c82000-02-29 22:57:47 +0000[diff] [blame]1218<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]1219markup-based structured documents. Here is <a name="example">an example XML
1220document</a>:</p>
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]1221<pre>&lt;?xml version="1.0"?&gt;
1222&lt;EXAMPLE prop1="gnome is great" prop2="&amp;amp; linux too"&gt;
1223 &lt;head&gt;
1224 &lt;title&gt;Welcome to Gnome&lt;/title&gt;
1225 &lt;/head&gt;
1226 &lt;chapter&gt;
1227 &lt;title&gt;The Linux adventure&lt;/title&gt;
1228 &lt;p&gt;bla bla bla ...&lt;/p&gt;
1229 &lt;image href="linus.gif"/&gt;
1230 &lt;p&gt;...&lt;/p&gt;
1231 &lt;/chapter&gt;
1232&lt;/EXAMPLE&gt;</pre>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]1233
Daniel Veillard402e8c82000-02-29 22:57:47 +0000[diff] [blame]1234<p>The first line specifies that it's an XML document and gives useful
1235information about its encoding. Then the document is a text format whose
1236structure is specified by tags between brackets. <strong>Each tag opened has
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]1237to be closed</strong>. XML is pedantic about this. However, if a tag is empty
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]1238(no content), a single tag can serve as both the opening and closing tag if
1239it ends with <code>/&gt;</code> rather than with <code>&gt;</code>. Note
1240that, for example, the image tag has no content (just an attribute) and is
1241closed by ending the tag with <code>/&gt;</code>.</p>
Daniel Veillardccb09631998-10-27 06:21:04 +0000[diff] [blame]1242
Daniel Veillard402e8c82000-02-29 22:57:47 +0000[diff] [blame]1243<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]1244structured document maintenance (where it follows the steps of SGML) to
1245simple data encoding mechanisms like configuration file formatting (glade),
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]1246spreadsheets (gnumeric), or even shorter lived documents such as WebDAV where
1247it is used to encode remote calls between a client and a server.</p>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]1248
Daniel Veillard82687162001-01-22 15:32:01 +0000[diff] [blame]1249<h2><a name="XSLT">XSLT</a></h2>
1250
Daniel Veillard6e6a6cc2001-02-15 15:55:44 +0000[diff] [blame]1251<p>Check <a href="http://xmlsoft.org/XSLT">the separate libxslt page</a></p>
1252
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]1253<p><a href="http://www.w3.org/TR/xslt">XSL Transformations</a>, is a
1254language for transforming XML documents into other XML documents (or
1255HTML/textual output).</p>
Daniel Veillard82687162001-01-22 15:32:01 +0000[diff] [blame]1256
1257<p>A separate library called libxslt is being built on top of libxml2. This
1258module "libxslt" can be found in the Gnome CVS base too.</p>
1259
Daniel Veillard383b1472001-01-23 11:39:52 +0000[diff] [blame]1260<p>You can check the <a
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]1261href="http://cvs.gnome.org/lxr/source/libxslt/FEATURES">features</a>
1262supported and the progresses on the <a
Daniel Veillard82687162001-01-22 15:32:01 +0000[diff] [blame]1263href="http://cvs.gnome.org/lxr/source/libxslt/ChangeLog">Changelog</a></p>
1264
Daniel Veillardb8cfbd12001-10-25 10:53:28 +0000[diff] [blame]1265<h2><a name="architecture">libxml architecture</a></h2>
Daniel Veillard4540be42000-08-19 16:40:28 +0000[diff] [blame]1266
Daniel Veillardec70e912001-02-26 20:10:45 +0000[diff] [blame]1267<p>Libxml is made of multiple components; some of them are optional, and most
1268of the block interfaces are public. The main components are:</p>
Daniel Veillard4540be42000-08-19 16:40:28 +0000[diff] [blame]1269<ul>
1270 <li>an Input/Output layer</li>
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]1271 <li>FTP and HTTP client layers (optional)</li>
Daniel Veillard4540be42000-08-19 16:40:28 +0000[diff] [blame]1272 <li>an Internationalization layer managing the encodings support</li>
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]1273 <li>a URI module</li>
Daniel Veillard4540be42000-08-19 16:40:28 +0000[diff] [blame]1274 <li>the XML parser and its basic SAX interface</li>
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]1275 <li>an HTML parser using the same SAX interface (optional)</li>
Daniel Veillard4540be42000-08-19 16:40:28 +0000[diff] [blame]1276 <li>a SAX tree module to build an in-memory DOM representation</li>
1277 <li>a tree module to manipulate the DOM representation</li>
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]1278 <li>a validation module using the DOM representation (optional)</li>
Daniel Veillard4540be42000-08-19 16:40:28 +0000[diff] [blame]1279 <li>an XPath module for global lookup in a DOM representation
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]1280 (optional)</li>
1281 <li>a debug module (optional)</li>
Daniel Veillard4540be42000-08-19 16:40:28 +0000[diff] [blame]1282</ul>
1283
1284<p>Graphically this gives the following:</p>
1285
1286<p><img src="libxml.gif" alt="a graphical view of the various"></p>
1287
1288<p></p>
1289
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]1290<h2><a name="tree">The tree output</a></h2>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]1291
1292<p>The parser returns a tree built during the document analysis. The value
Daniel Veillard402e8c82000-02-29 22:57:47 +0000[diff] [blame]1293returned is an <strong>xmlDocPtr</strong> (i.e., a pointer to an
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]1294<strong>xmlDoc</strong> structure). This structure contains information such
Daniel Veillard306be992000-07-03 12:38:45 +0000[diff] [blame]1295as the file name, the document type, and a <strong>children</strong> pointer
1296which is the root of the document (or more exactly the first child under the
1297root which is the document). The tree is made of <strong>xmlNode</strong>s,
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]1298chained in double-linked lists of siblings and with a children&lt;-&gt;parent
Daniel Veillard306be992000-07-03 12:38:45 +0000[diff] [blame]1299relationship. An xmlNode can also carry properties (a chain of xmlAttr
1300structures). An attribute may have a value which is a list of TEXT or
1301ENTITY_REF nodes.</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]1302
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]1303<p>Here is an example (erroneous with respect to the XML spec since there
1304should be only one ELEMENT under the root):</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]1305
1306<p><img src="structure.gif" alt=" structure.gif "></p>
1307
1308<p>In the source package there is a small program (not installed by default)
Daniel Veillard361d8452000-04-03 19:48:13 +0000[diff] [blame]1309called <strong>xmllint</strong> which parses XML files given as argument and
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]1310prints them back as parsed. This is useful for detecting errors both in XML
1311code and in the XML parser itself. It has an option <strong>--debug</strong>
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]1312which prints the actual in-memory structure of the document; here is the
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]1313result with the <a href="#example">example</a> given before:</p>
Daniel Veillard10c6a8f1998-10-28 01:00:12 +0000[diff] [blame]1314<pre>DOCUMENT
1315version=1.0
1316standalone=true
1317 ELEMENT EXAMPLE
1318 ATTRIBUTE prop1
1319 TEXT
1320 content=gnome is great
1321 ATTRIBUTE prop2
1322 ENTITY_REF
1323 TEXT
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]1324 content= linux too
Daniel Veillard402e8c82000-02-29 22:57:47 +0000[diff] [blame]1325 ELEMENT head
Daniel Veillard10c6a8f1998-10-28 01:00:12 +0000[diff] [blame]1326 ELEMENT title
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]1327 TEXT
1328 content=Welcome to Gnome
Daniel Veillard10c6a8f1998-10-28 01:00:12 +0000[diff] [blame]1329 ELEMENT chapter
1330 ELEMENT title
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]1331 TEXT
1332 content=The Linux adventure
Daniel Veillard10c6a8f1998-10-28 01:00:12 +0000[diff] [blame]1333 ELEMENT p
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]1334 TEXT
1335 content=bla bla bla ...
Daniel Veillard10c6a8f1998-10-28 01:00:12 +0000[diff] [blame]1336 ELEMENT image
1337 ATTRIBUTE href
1338 TEXT
1339 content=linus.gif
1340 ELEMENT p
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]1341 TEXT
1342 content=...</pre>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]1343
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]1344<p>This should be useful for learning the internal representation model.</p>
Daniel Veillardccb09631998-10-27 06:21:04 +0000[diff] [blame]1345
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]1346<h2><a name="interface">The SAX interface</a></h2>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]1347
Daniel Veillard402e8c82000-02-29 22:57:47 +0000[diff] [blame]1348<p>Sometimes the DOM tree output is just too large to fit reasonably into
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]1349memory. 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]1350loaded using libxml), it's better to use the SAX interface of libxml. SAX is
1351a <strong>callback-based interface</strong> to the parser. Before parsing,
1352the application layer registers a customized set of callbacks which are
1353called by the library as it progresses through the XML input.</p>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]1354
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]1355<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]1356libxml, see the <a
1357href="http://www.daa.com.au/~james/gnome/xml-sax/xml-sax.html">nice
1358documentation</a>.written by <a href="mailto:james@daa.com.au">James
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]1359Henstridge</a>.</p>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]1360
1361<p>You can debug the SAX behaviour by using the <strong>testSAX</strong>
1362program located in the gnome-xml module (it's usually not shipped in the
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]1363binary packages of libxml, but you can find it in the tar source
Daniel Veillard402e8c82000-02-29 22:57:47 +0000[diff] [blame]1364distribution). Here is the sequence of callbacks that would be reported by
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]1365testSAX when parsing the example XML document shown earlier:</p>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]1366<pre>SAX.setDocumentLocator()
1367SAX.startDocument()
1368SAX.getEntity(amp)
1369SAX.startElement(EXAMPLE, prop1='gnome is great', prop2='&amp;amp; linux too')
1370SAX.characters( , 3)
1371SAX.startElement(head)
1372SAX.characters( , 4)
1373SAX.startElement(title)
1374SAX.characters(Welcome to Gnome, 16)
1375SAX.endElement(title)
1376SAX.characters( , 3)
1377SAX.endElement(head)
1378SAX.characters( , 3)
1379SAX.startElement(chapter)
1380SAX.characters( , 4)
1381SAX.startElement(title)
1382SAX.characters(The Linux adventure, 19)
1383SAX.endElement(title)
1384SAX.characters( , 4)
1385SAX.startElement(p)
1386SAX.characters(bla bla bla ..., 15)
1387SAX.endElement(p)
1388SAX.characters( , 4)
1389SAX.startElement(image, href='linus.gif')
1390SAX.endElement(image)
1391SAX.characters( , 4)
1392SAX.startElement(p)
1393SAX.characters(..., 3)
1394SAX.endElement(p)
1395SAX.characters( , 3)
1396SAX.endElement(chapter)
1397SAX.characters( , 1)
1398SAX.endElement(EXAMPLE)
1399SAX.endDocument()</pre>
1400
Daniel Veillardec70e912001-02-26 20:10:45 +0000[diff] [blame]1401<p>Most of the other interfaces of libxml are based on the DOM tree-building
1402facility, so nearly everything up to the end of this document presupposes the
1403use of the standard DOM tree build. Note that the DOM tree itself is built by
1404a set of registered default callbacks, without internal specific
1405interface.</p>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]1406
Daniel Veillardb8cfbd12001-10-25 10:53:28 +0000[diff] [blame]1407<h2><a name="Validation">Validation &amp; DTDs</a></h2>
1408
1409<p>Table of Content:</p>
1410<ol>
1411 <li><a href="#General5">General overview</a></li>
1412 <li><a href="#definition">The definition</a></li>
1413 <li><a href="#Simple">Simple rules</a>
1414 <ol>
Daniel Veillard9c466822001-10-25 12:03:39 +0000[diff] [blame]1415 <li><a href="#reference">How to reference a DTD from a document</a></li>
Daniel Veillardb8cfbd12001-10-25 10:53:28 +0000[diff] [blame]1416 <li><a href="#Declaring">Declaring elements</a></li>
1417 <li><a href="#Declaring1">Declaring attributes</a></li>
1418 </ol>
1419 </li>
1420 <li><a href="#Some">Some examples</a></li>
1421 <li><a href="#validate">How to validate</a></li>
1422 <li><a href="#Other">Other resources</a></li>
1423</ol>
1424
1425<h3><a name="General5">General overview</a></h3>
1426
1427<p>Well what is validation and what is a DTD ?</p>
1428
1429<p>DTD is the acronym for Document Type Definition. This is a description of
1430the content for a familly of XML files. This is part of the XML 1.0
1431specification, and alows to describe and check that a given document instance
1432conforms to a set of rules detailing its structure and content.</p>
1433
1434<p>Validation is the process of checking a document against a DTD (more
1435generally against a set of construction rules).</p>
1436
1437<p>The validation process and building DTDs are the two most difficult parts
1438of the XML life cycle. Briefly a DTD defines all the possibles element to be
1439found within your document, what is the formal shape of your document tree
1440(by defining the allowed content of an element, either text, a regular
1441expression for the allowed list of children, or mixed content i.e. both text
1442and children). The DTD also defines the allowed attributes for all elements
1443and the types of the attributes.</p>
1444
1445<h3><a name="definition1">The definition</a></h3>
1446
1447<p>The <a href="http://www.w3.org/TR/REC-xml">W3C XML Recommendation</a> (<a
1448href="http://www.xml.com/axml/axml.html">Tim Bray's annotated version of
1449Rev1</a>):</p>
1450<ul>
1451 <li><a href="http://www.w3.org/TR/REC-xml#elemdecls">Declaring
1452 elements</a></li>
1453 <li><a href="http://www.w3.org/TR/REC-xml#attdecls">Declaring
1454 attributes</a></li>
1455</ul>
1456
1457<p>(unfortunately) all this is inherited from the SGML world, the syntax is
1458ancient...</p>
1459
1460<h3><a name="Simple1">Simple rules</a></h3>
1461
1462<p>Writing DTD can be done in multiple ways, the rules to build them if you
1463need something fixed or something which can evolve over time can be radically
1464different. Really complex DTD like Docbook ones are flexible but quite harder
1465to design. I will just focuse on DTDs for a formats with a fixed simple
1466structure. It is just a set of basic rules, and definitely not exhaustive nor
1467useable for complex DTD design.</p>
1468
1469<h4><a name="reference1">How to reference a DTD from a document</a>:</h4>
1470
1471<p>Assuming the top element of the document is <code>spec</code> and the dtd
1472is placed in the file <code>mydtd</code> in the subdirectory
1473<code>dtds</code> of the directory from where the document were loaded:</p>
1474
1475<p><code>&lt;!DOCTYPE spec SYSTEM "dtds/mydtd"&gt;</code></p>
1476
1477<p>Notes:</p>
1478<ul>
1479 <li>the system string is actually an URI-Reference (as defined in <a
1480 href="http://www.ietf.org/rfc/rfc2396.txt">RFC 2396</a>) so you can use a
1481 full URL string indicating the location of your DTD on the Web, this is a
1482 really good thing to do if you want others to validate your document</li>
1483 <li>it is also possible to associate a <code>PUBLIC</code> identifier (a
1484 magic string) so that the DTd is looked up in catalogs on the client side
1485 without having to locate it on the web</li>
1486 <li>a dtd contains a set of elements and attributes declarations, but they
1487 don't define what the root of the document should be. This is explicitely
1488 told to the parser/validator as the first element of the
1489 <code>DOCTYPE</code> declaration.</li>
1490</ul>
1491
1492<h4><a name="Declaring2">Declaring elements</a>:</h4>
1493
1494<p>The following declares an element <code>spec</code>:</p>
1495
1496<p><code>&lt;!ELEMENT spec (front, body, back?)&gt;</code></p>
1497
1498<p>it also expresses that the spec element contains one <code>front</code>,
1499one <code>body</code> and one optionnal <code>back</code> children elements
1500in this order. The declaration of one element of the structure and its
1501content are done in a single declaration. Similary the following declares
1502<code>div1</code> elements:</p>
1503
1504<p><code>&lt;!ELEMENT div1 (head, (p | list | note)*, div2*)&gt;</code></p>
1505
1506<p>means div1 contains one <code>head</code> then a series of optional
1507<code>p</code>, <code>list</code>s and <code>note</code>s and then an
1508optional <code>div2</code>. And last but not least an element can contain
1509text:</p>
1510
1511<p><code>&lt;!ELEMENT b (#PCDATA)&gt;</code></p>
1512
1513<p><code>b</code> contains text or being of mixed content (text and elements
1514in no particular order):</p>
1515
1516<p><code>&lt;!ELEMENT p (#PCDATA|a|ul|b|i|em)*&gt;</code></p>
1517
1518<p><code>p </code>can contain text or <code>a</code>, <code>ul</code>,
1519<code>b</code>, <code>i </code>or <code>em</code> elements in no particular
1520order.</p>
1521
1522<h4><a name="Declaring1">Declaring attributes</a>:</h4>
1523
1524<p>again the attributes declaration includes their content definition:</p>
1525
1526<p><code>&lt;!ATTLIST termdef name CDATA #IMPLIED&gt;</code></p>
1527
1528<p>means that the element <code>termdef</code> can have a <code>name</code>
1529attribute containing text (<code>CDATA</code>) and which is optionnal
1530(<code>#IMPLIED</code>). The attribute value can also be defined within a
1531set:</p>
1532
1533<p><code>&lt;!ATTLIST list type (bullets|ordered|glossary)
1534"ordered"&gt;</code></p>
1535
1536<p>means <code>list</code> element have a <code>type</code> attribute with 3
1537allowed values "bullets", "ordered" or "glossary" and which default to
1538"ordered" if the attribute is not explicitely specified.</p>
1539
1540<p>The content type of an attribute can be text (<code>CDATA</code>),
1541anchor/reference/references
1542(<code>ID</code>/<code>IDREF</code>/<code>IDREFS</code>), entity(ies)
1543(<code>ENTITY</code>/<code>ENTITIES</code>) or name(s)
1544(<code>NMTOKEN</code>/<code>NMTOKENS</code>). The following defines that a
1545<code>chapter</code> element can have an optional <code>id</code> attribute
1546of type <code>ID</code>, usable for reference from attribute of type
1547IDREF:</p>
1548
1549<p><code>&lt;!ATTLIST chapter id ID #IMPLIED&gt;</code></p>
1550
1551<p>The last value of an attribute definition can be <code>#REQUIRED
1552</code>meaning that the attribute has to be given, <code>#IMPLIED</code>
1553meaning that it is optional, or the default value (possibly prefixed by
1554<code>#FIXED</code> if it is the only allowed).</p>
1555
1556<p>Notes:</p>
1557<ul>
1558 <li>usually the attributes pertaining to a given element are declared in a
1559 single expression, but it is just a convention adopted by a lot of DTD
1560 writers:
1561 <pre>&lt;!ATTLIST termdef
1562 id ID #REQUIRED
1563 name CDATA #IMPLIED&gt;</pre>
1564 <p>The previous construct defines both <code>id</code> and
1565 <code>name</code> attributes for the element <code>termdef</code></p>
1566 </li>
1567</ul>
1568
1569<h3><a name="Some1">Some examples</a></h3>
1570
1571<p>The directory <code>test/valid/dtds/</code> in the libxml distribution
1572contains some complex DTD examples. The <code>test/valid/dia.xml</code>
1573example shows an XML file where the simple DTD is directly included within
1574the document.</p>
1575
1576<h3><a name="validate1">How to validate</a></h3>
1577
1578<p>The simplest is to use the xmllint program comming with libxml. The
1579<code>--valid</code> option turn on validation of the files given as input,
1580for example the following validates a copy of the first revision of the XML
15811.0 specification:</p>
1582
1583<p><code>xmllint --valid --noout test/valid/REC-xml-19980210.xml</code></p>
1584
1585<p>the -- noout is used to not output the resulting tree.</p>
1586
1587<p>The <code>--dtdvalid dtd</code> allows to validate the document(s) against
1588a given DTD.</p>
1589
1590<p>Libxml exports an API to handle DTDs and validation, check the <a
1591href="http://xmlsoft.org/html/libxml-valid.html">associated
1592description</a>.</p>
1593
1594<h3><a name="Other1">Other resources</a></h3>
1595
1596<p>DTDs are as old as SGML. So there may be a number of examples on-line, I
1597will just list one for now, others pointers welcome:</p>
1598<ul>
1599 <li><a href="http://www.xml101.com:8081/dtd/">XML-101 DTD</a></li>
1600</ul>
1601
1602<p>I suggest looking at the examples found under test/valid/dtd and any of
1603the large number of books available on XML. The dia example in test/valid
1604should be both simple and complete enough to allow you to build your own.</p>
1605
1606<p></p>
1607
1608<h2><a name="Memory">Memory Management</a></h2>
1609
1610<p>Table of Content:</p>
1611<ol>
1612 <li><a href="#General3">General overview</a></li>
Daniel Veillard9c466822001-10-25 12:03:39 +0000[diff] [blame]1613 <li><a href="#setting">Setting libxml set of memory routines</a></li>
Daniel Veillardb8cfbd12001-10-25 10:53:28 +0000[diff] [blame]1614 <li><a href="#cleanup">Cleaning up after parsing</a></li>
1615 <li><a href="#Debugging">Debugging routines</a></li>
1616 <li><a href="#General4">General memory requirements</a></li>
1617</ol>
1618
1619<h3><a name="General3">General overview</a></h3>
1620
1621<p>The module <code><a
1622href="http://xmlsoft.org/html/libxml-xmlmemory.html">xmlmemory.h</a></code>
1623provides the interfaces to the libxml memory system:</p>
1624<ul>
1625 <li>libxml does not use the libc memory allocator directly but xmlFree(),
1626 xmlMalloc() and xmlRealloc()</li>
1627 <li>those routines can be reallocated to a specific set of routine, by
1628 default the libc ones i.e. free(), malloc() and realloc()</li>
1629 <li>the xmlmemory.c module includes a set of debugging routine</li>
1630</ul>
1631
1632<h3><a name="setting">Setting libxml set of memory routines</a></h3>
1633
1634<p>It is sometimes useful to not use the default memory allocator, either for
1635debugging, analysis or to implement a specific behaviour on memory management
1636(like on embedded systems). Two function calls are available to do so:</p>
1637<ul>
1638 <li><a href="http://xmlsoft.org/html/libxml-xmlmemory.html">xmlMemGet ()</a>
1639 which return the current set of functions in use by the parser</li>
1640 <li><a
1641 href="http://xmlsoft.org/html/libxml-xmlmemory.html">xmlMemSetup()</a>
1642 which allow to set up a new set of memory allocation functions</li>
1643</ul>
1644
1645<p>Of course a call to xmlMemSetup() should probably be done before calling
1646any other libxml routines (unless you are sure your allocations routines are
1647compatibles).</p>
1648
1649<h3><a name="cleanup">Cleaning up after parsing</a></h3>
1650
1651<p>Libxml is not stateless, there is a few set of memory structures needing
1652allocation before the parser is fully functionnal (some encoding structures
1653for example). This also mean that once parsing is finished there is a tiny
1654amount of memory (a few hundred bytes) which can be recollected if you don't
1655reuse the parser immediately:</p>
1656<ul>
1657 <li><a href="http://xmlsoft.org/html/libxml-parser.html">xmlCleanupParser
1658 ()</a>
1659 is a centralized routine to free the parsing states. Note that it won't
1660 deallocate any produced tree if any (use the xmlFreeDoc() and related
1661 routines for this).</li>
1662 <li><a href="http://xmlsoft.org/html/libxml-parser.html">xmlInitParser
1663 ()</a>
1664 is the dual routine allowing to preallocate the parsing state which can
1665 be useful for example to avoid initialization reentrancy problems when
1666 using libxml in multithreaded applications</li>
1667</ul>
1668
1669<p>Generally xmlCleanupParser() is safe, if needed the state will be rebuild
1670at the next invocation of parser routines, but be careful of the consequences
1671in multithreaded applications.</p>
1672
1673<h3><a name="Debugging">Debugging routines</a></h3>
1674
1675<p>When configured using --with-mem-debug flag (off by default), libxml uses
1676a set of memory allocation debugging routineskeeping track of all allocated
1677blocks and the location in the code where the routine was called. A couple of
1678other debugging routines allow to dump the memory allocated infos to a file
1679or call a specific routine when a given block number is allocated:</p>
1680<ul>
1681 <li><a
1682 href="http://xmlsoft.org/html/libxml-xmlmemory.html">xmlMallocLoc()</a>
1683 <a
1684 href="http://xmlsoft.org/html/libxml-xmlmemory.html">xmlReallocLoc()</a>
1685 and <a
1686 href="http://xmlsoft.org/html/libxml-xmlmemory.html">xmlMemStrdupLoc()</a>
1687 are the memory debugging replacement allocation routines</li>
1688 <li><a href="http://xmlsoft.org/html/libxml-xmlmemory.html">xmlMemoryDump
1689 ()</a>
1690 dumps all the informations about the allocated memory block lefts in the
1691 <code>.memdump</code> file</li>
1692</ul>
1693
1694<p>When developping libxml memory debug is enabled, the tests programs call
1695xmlMemoryDump () and the "make test" regression tests will check for any
1696memory leak during the full regression test sequence, this helps a lot
1697ensuring that libxml does not leak memory and bullet proof memory
1698allocations use (some libc implementations are known to be far too permissive
1699resulting in major portability problems!).</p>
1700
1701<p>If the .memdump reports a leak, it displays the allocation function and
1702also tries to give some informations about the content and structure of the
1703allocated blocks left. This is sufficient in most cases to find the culprit,
1704but not always. Assuming the allocation problem is reproductible, it is
1705possible to find more easilly:</p>
1706<ol>
1707 <li>write down the block number xxxx not allocated</li>
1708 <li>export the environement variable XML_MEM_BREAKPOINT=xxxx</li>
1709 <li>run the program under a debugger and set a breakpoint on
1710 xmlMallocBreakpoint() a specific function called when this precise block
1711 is allocated</li>
1712 <li>when the breakpoint is reached you can then do a fine analysis of the
1713 allocation an step to see the condition resulting in the missing
1714 deallocation.</li>
1715</ol>
1716
1717<p>I used to use a commercial tool to debug libxml memory problems but after
1718noticing that it was not detecting memory leaks that simple mechanism was
1719used and proved extremely efficient until now.</p>
1720
1721<h3><a name="General4">General memory requirements</a></h3>
1722
1723<p>How much libxml memory require ? It's hard to tell in average it depends
1724of a number of things:</p>
1725<ul>
1726 <li>the parser itself should work in a fixed amout of memory, except for
1727 information maintained about the stacks of names and entities locations.
1728 The I/O and encoding handlers will probably account for a few KBytes.
1729 This is true for both the XML and HTML parser (though the HTML parser
1730 need more state).</li>
1731 <li>If you are generating the DOM tree then memory requirements will grow
1732 nearly lineary with the size of the data. In general for a balanced
1733 textual document the internal memory requirement is about 4 times the
1734 size of the UTF8 serialization of this document (exmple the XML-1.0
1735 recommendation is a bit more of 150KBytes and takes 650KBytes of main
1736 memory when parsed). Validation will add a amount of memory required for
1737 maintaining the external Dtd state which should be linear with the
1738 complexity of the content model defined by the Dtd</li>
1739 <li>If you don't care about the advanced features of libxml like
1740 validation, DOM, XPath or XPointer, but really need to work fixed memory
1741 requirements, then the SAX interface should be used.</li>
1742</ul>
1743
1744<p></p>
1745
1746<h2><a name="Encodings">Encodings support</a></h2>
1747
1748<p>Table of Content:</p>
1749<ol>
1750 <li><a href="encoding.html#What">What does internationalization support
1751 mean ?</a></li>
1752 <li><a href="encoding.html#internal">The internal encoding, how and
1753 why</a></li>
1754 <li><a href="encoding.html#implemente">How is it implemented ?</a></li>
1755 <li><a href="encoding.html#Default">Default supported encodings</a></li>
1756 <li><a href="encoding.html#extend">How to extend the existing
1757 support</a></li>
1758</ol>
1759
1760<h3><a name="What">What does internationalization support mean ?</a></h3>
1761
1762<p>XML was designed from the start to allow the support of any character set
1763by using Unicode. Any conformant XML parser has to support the UTF-8 and
1764UTF-16 default encodings which can both express the full unicode ranges. UTF8
1765is a variable length encoding whose greatest point are to resuse the same
1766emcoding for ASCII and to save space for Western encodings, but it is a bit
1767more complex to handle in practice. UTF-16 use 2 bytes per characters (and
1768sometimes combines two pairs), it makes implementation easier, but looks a
1769bit overkill for Western languages encoding. Moreover the XML specification
1770allows document to be encoded in other encodings at the condition that they
1771are clearly labelled as such. For example the following is a wellformed XML
1772document encoded in ISO-8859 1 and using accentuated letter that we French
1773likes for both markup and content:</p>
1774<pre>&lt;?xml version="1.0" encoding="ISO-8859-1"?&gt;
1775&lt;très&gt;là&lt;/très&gt;</pre>
1776
1777<p>Having internationalization support in libxml means the foolowing:</p>
1778<ul>
1779 <li>the document is properly parsed</li>
1780 <li>informations about it's encoding are saved</li>
1781 <li>it can be modified</li>
1782 <li>it can be saved in its original encoding</li>
1783 <li>it can also be saved in another encoding supported by libxml (for
1784 example straight UTF8 or even an ASCII form)</li>
1785</ul>
1786
1787<p>Another very important point is that the whole libxml API, with the
1788exception of a few routines to read with a specific encoding or save to a
1789specific encoding, is completely agnostic about the original encoding of the
1790document.</p>
1791
1792<p>It should be noted too that the HTML parser embedded in libxml now obbey
1793the same rules too, the following document will be (as of 2.2.2) handled in
1794an internationalized fashion by libxml too:</p>
1795<pre>&lt;!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN"
1796 "http://www.w3.org/TR/REC-html40/loose.dtd"&gt;
1797&lt;html lang="fr"&gt;
1798&lt;head&gt;
1799 &lt;META HTTP-EQUIV="Content-Type" CONTENT="text/html; charset=ISO-8859-1"&gt;
1800&lt;/head&gt;
1801&lt;body&gt;
1802&lt;p&gt;W3C crée des standards pour le Web.&lt;/body&gt;
1803&lt;/html&gt;</pre>
1804
1805<h3><a name="internal">The internal encoding, how and why</a></h3>
1806
1807<p>One of the core decision was to force all documents to be converted to a
1808default internal encoding, and that encoding to be UTF-8, here are the
1809rationale for those choices:</p>
1810<ul>
1811 <li>keeping the native encoding in the internal form would force the libxml
1812 users (or the code associated) to be fully aware of the encoding of the
1813 original document, for examples when adding a text node to a document,
1814 the content would have to be provided in the document encoding, i.e. the
1815 client code would have to check it before hand, make sure it's conformant
1816 to the encoding, etc ... Very hard in practice, though in some specific
1817 cases this may make sense.</li>
1818 <li>the second decision was which encoding. From the XML spec only UTF8 and
1819 UTF16 really makes sense as being the two only encodings for which there
1820 is amndatory support. UCS-4 (32 bits fixed size encoding) could be
1821 considered an intelligent choice too since it's a direct Unicode mapping
1822 support. I selected UTF-8 on the basis of efficiency and compatibility
1823 with surrounding software:
1824 <ul>
1825 <li>UTF-8 while a bit more complex to convert from/to (i.e. slightly
1826 more costly to import and export CPU wise) is also far more compact
1827 than UTF-16 (and UCS-4) for a majority of the documents I see it used
1828 for right now (RPM RDF catalogs, advogato data, various configuration
1829 file formats, etc.) and the key point for today's computer
1830 architecture is efficient uses of caches. If one nearly double the
1831 memory requirement to store the same amount of data, this will trash
1832 caches (main memory/external caches/internal caches) and my take is
1833 that this harms the system far more than the CPU requirements needed
1834 for the conversion to UTF-8</li>
1835 <li>Most of libxml version 1 users were using it with straight ASCII
1836 most of the time, doing the conversion with an internal encoding
1837 requiring all their code to be rewritten was a serious show-stopper
1838 for using UTF-16 or UCS-4.</li>
1839 <li>UTF-8 is being used as the de-facto internal encoding standard for
1840 related code like the <a href="http://www.pango.org/">pango</a>
1841 upcoming Gnome text widget, and a lot of Unix code (yep another place
1842 where Unix programmer base takes a different approach from Microsoft
1843 - they are using UTF-16)</li>
1844 </ul>
1845 </li>
1846</ul>
1847
1848<p>What does this mean in practice for the libxml user:</p>
1849<ul>
1850 <li>xmlChar, the libxml data type is a byte, those bytes must be assembled
1851 as UTF-8 valid strings. The proper way to terminate an xmlChar * string
1852 is simply to append 0 byte, as usual.</li>
1853 <li>One just need to make sure that when using chars outside the ASCII set,
1854 the values has been properly converted to UTF-8</li>
1855</ul>
1856
1857<h3><a name="implemente">How is it implemented ?</a></h3>
1858
1859<p>Let's describe how all this works within libxml, basically the I18N
1860(internationalization) support get triggered only during I/O operation, i.e.
1861when reading a document or saving one. Let's look first at the reading
1862sequence:</p>
1863<ol>
1864 <li>when a document is processed, we usually don't know the encoding, a
1865 simple heuristic allows to detect UTF-18 and UCS-4 from whose where the
1866 ASCII range (0-0x7F) maps with ASCII</li>
1867 <li>the xml declaration if available is parsed, including the encoding
1868 declaration. At that point, if the autodetected encoding is different
1869 from the one declared a call to xmlSwitchEncoding() is issued.</li>
1870 <li>If there is no encoding declaration, then the input has to be in either
1871 UTF-8 or UTF-16, if it is not then at some point when processing the
1872 input, the converter/checker of UTF-8 form will raise an encoding error.
1873 You may end-up with a garbled document, or no document at all ! Example:
1874 <pre>~/XML -&gt; ./xmllint err.xml
1875err.xml:1: error: Input is not proper UTF-8, indicate encoding !
1876&lt;très&gt;là&lt;/très&gt;
1877 ^
1878err.xml:1: error: Bytes: 0xE8 0x73 0x3E 0x6C
1879&lt;très&gt;là&lt;/très&gt;
1880 ^</pre>
1881 </li>
1882 <li>xmlSwitchEncoding() does an encoding name lookup, canonalize it, and
1883 then search the default registered encoding converters for that encoding.
1884 If it's not within the default set and iconv() support has been compiled
1885 it, it will ask iconv for such an encoder. If this fails then the parser
1886 will report an error and stops processing:
1887 <pre>~/XML -&gt; ./xmllint err2.xml
1888err2.xml:1: error: Unsupported encoding UnsupportedEnc
1889&lt;?xml version="1.0" encoding="UnsupportedEnc"?&gt;
1890 ^</pre>
1891 </li>
1892 <li>From that point the encoder process progressingly the input (it is
1893 plugged as a front-end to the I/O module) for that entity. It captures
1894 and convert on-the-fly the document to be parsed to UTF-8. The parser
1895 itself just does UTF-8 checking of this input and process it
1896 transparently. The only difference is that the encoding information has
1897 been added to the parsing context (more precisely to the input
1898 corresponding to this entity).</li>
1899 <li>The result (when using DOM) is an internal form completely in UTF-8
1900 with just an encoding information on the document node.</li>
1901</ol>
1902
1903<p>Ok then what's happen when saving the document (assuming you
1904colllected/built an xmlDoc DOM like structure) ? It depends on the function
1905called, xmlSaveFile() will just try to save in the original encoding, while
1906xmlSaveFileTo() and xmlSaveFileEnc() can optionally save to a given
1907encoding:</p>
1908<ol>
1909 <li>if no encoding is given, libxml will look for an encoding value
1910 associated to the document and if it exists will try to save to that
1911 encoding,
1912 <p>otherwise everything is written in the internal form, i.e. UTF-8</p>
1913 </li>
1914 <li>so if an encoding was specified, either at the API level or on the
1915 document, libxml will again canonalize the encoding name, lookup for a
1916 converter in the registered set or through iconv. If not found the
1917 function will return an error code</li>
1918 <li>the converter is placed before the I/O buffer layer, as another kind of
1919 buffer, then libxml will simply push the UTF-8 serialization to through
1920 that buffer, which will then progressively be converted and pushed onto
1921 the I/O layer.</li>
1922 <li>It is possible that the converter code fails on some input, for example
1923 trying to push an UTF-8 encoded chinese character through the UTF-8 to
1924 ISO-8859-1 converter won't work. Since the encoders are progressive they
1925 will just report the error and the number of bytes converted, at that
1926 point libxml will decode the offending character, remove it from the
1927 buffer and replace it with the associated charRef encoding &amp;#123; and
1928 resume the convertion. This guarante that any document will be saved
1929 without losses (except for markup names where this is not legal, this is
1930 a problem in the current version, in pactice avoid using non-ascci
1931 characters for tags or attributes names @@). A special "ascii" encoding
1932 name is used to save documents to a pure ascii form can be used when
1933 portability is really crucial</li>
1934</ol>
1935
1936<p>Here is a few examples based on the same test document:</p>
1937<pre>~/XML -&gt; ./xmllint isolat1
1938&lt;?xml version="1.0" encoding="ISO-8859-1"?&gt;
1939&lt;très&gt;là&lt;/très&gt;
1940~/XML -&gt; ./xmllint --encode UTF-8 isolat1
1941&lt;?xml version="1.0" encoding="UTF-8"?&gt;
1942&lt;très&gt;là  &lt;/très&gt;
1943~/XML -&gt; </pre>
1944
1945<p>The same processing is applied (and reuse most of the code) for HTML I18N
1946processing. Looking up and modifying the content encoding is a bit more
1947difficult since it is located in a &lt;meta&gt; tag under the &lt;head&gt;,
1948so a couple of functions htmlGetMetaEncoding() and htmlSetMetaEncoding() have
1949been provided. The parser also attempts to switch encoding on the fly when
1950detecting such a tag on input. Except for that the processing is the same
1951(and again reuses the same code).</p>
1952
1953<h3><a name="Default">Default supported encodings</a></h3>
1954
1955<p>libxml has a set of default converters for the following encodings
1956(located in encoding.c):</p>
1957<ol>
1958 <li>UTF-8 is supported by default (null handlers)</li>
1959 <li>UTF-16, both little and big endian</li>
1960 <li>ISO-Latin-1 (ISO-8859-1) covering most western languages</li>
1961 <li>ASCII, useful mostly for saving</li>
1962 <li>HTML, a specific handler for the conversion of UTF-8 to ASCII with HTML
1963 predefined entities like &amp;copy; for the Copyright sign.</li>
1964</ol>
1965
1966<p>More over when compiled on an Unix platfor with iconv support the full set
1967of encodings supported by iconv can be instantly be used by libxml. On a
1968linux machine with glibc-2.1 the list of supported encodings and aliases fill
19693 full pages, and include UCS-4, the full set of ISO-Latin encodings, and the
1970various Japanese ones.</p>
1971
1972<h4>Encoding aliases</h4>
1973
1974<p>From 2.2.3, libxml has support to register encoding names aliases. The
1975goal is to be able to parse document whose encoding is supported but where
1976the name differs (for example from the default set of names accepted by
1977iconv). The following functions allow to register and handle new aliases for
1978existing encodings. Once registered libxml will automatically lookup the
1979aliases when handling a document:</p>
1980<ul>
1981 <li>int xmlAddEncodingAlias(const char *name, const char *alias);</li>
1982 <li>int xmlDelEncodingAlias(const char *alias);</li>
1983 <li>const char * xmlGetEncodingAlias(const char *alias);</li>
1984 <li>void xmlCleanupEncodingAliases(void);</li>
1985</ul>
1986
1987<h3><a name="extend">How to extend the existing support</a></h3>
1988
1989<p>Well adding support for new encoding, or overriding one of the encoders
1990(assuming it is buggy) should not be hard, just write an input and output
1991conversion routines to/from UTF-8, and register them using
1992xmlNewCharEncodingHandler(name, xxxToUTF8, UTF8Toxxx), and they will be
1993called automatically if the parser(s) encounter such an encoding name
1994(register it uppercase, this will help). The description of the encoders,
1995their arguments and expected return values are described in the encoding.h
1996header.</p>
1997
1998<p>A quick note on the topic of subverting the parser to use a different
1999internal encoding than UTF-8, in some case people will absolutely want to
2000keep the internal encoding different, I think it's still possible (but the
2001encoding must be compliant with ASCII on the same subrange) though I didn't
2002tried it. The key is to override the default conversion routines (by
2003registering null encoders/decoders for your charsets), and bypass the UTF-8
2004checking of the parser by setting the parser context charset
2005(ctxt-&gt;charset) to something different than XML_CHAR_ENCODING_UTF8, but
2006there is no guarantee taht this will work. You may also have some troubles
2007saving back.</p>
2008
2009<p>Basically proper I18N support is important, this requires at least
2010libxml-2.0.0, but a lot of features and corrections are really available only
2011starting 2.2.</p>
2012
2013<h2><a name="IO">I/O Interfaces</a></h2>
2014
2015<p>Table of Content:</p>
2016<ol>
2017 <li><a href="#General1">General overview</a></li>
2018 <li><a href="#basic">The basic buffer type</a></li>
2019 <li><a href="#Input">Input I/O handlers</a></li>
2020 <li><a href="#Output">Output I/O handlers</a></li>
2021 <li><a href="#entities">The entities loader</a></li>
2022 <li><a href="#Example2">Example of customized I/O</a></li>
2023</ol>
2024
2025<h3><a name="General1">General overview</a></h3>
2026
2027<p>The module <code><a
2028href="http://xmlsoft.org/html/libxml-xmlio.html">xmlIO.h</a></code> provides
2029the interfaces to the libxml I/O system. This consists of 4 main parts:</p>
2030<ul>
2031 <li>Entities loader, this is a routine which tries to fetch the entities
2032 (files) based on their PUBLIC and SYSTEM identifiers. The default loader
2033 don't look at the public identifier since libxml do not maintain a
2034 catalog. You can redefine you own entity loader by using
2035 <code>xmlGetExternalEntityLoader()</code> and
Daniel Veillard9c466822001-10-25 12:03:39 +0000[diff] [blame]2036 <code>xmlSetExternalEntityLoader()</code>. <a href="#entities">Check the
2037 example</a>.</li>
Daniel Veillardb8cfbd12001-10-25 10:53:28 +0000[diff] [blame]2038 <li>Input I/O buffers which are a commodity structure used by the parser(s)
2039 input layer to handle fetching the informations to feed the parser. This
2040 provides buffering and is also a placeholder where the encoding
2041 convertors to UTF8 are piggy-backed.</li>
2042 <li>Output I/O buffers are similar to the Input ones and fulfill similar
2043 task but when generating a serialization from a tree.</li>
2044 <li>A mechanism to register sets of I/O callbacks and associate them with
2045 specific naming schemes like the protocol part of the URIs.
2046 <p>This affect the default I/O operations and allows to use specific I/O
2047 handlers for certain names.</p>
2048 </li>
2049</ul>
2050
2051<p>The general mechanism used when loading http://rpmfind.net/xml.html for
2052example in the HTML parser is the following:</p>
2053<ol>
2054 <li>The default entity loader calls <code>xmlNewInputFromFile()</code> with
2055 the parsing context and the URI string.</li>
2056 <li>the URI string is checked against the existing registered handlers
2057 using their match() callback function, if the HTTP module was compiled
2058 in, it is registered and its match() function will succeeds</li>
2059 <li>the open() function of the handler is called and if successful will
2060 return an I/O Input buffer</li>
2061 <li>the parser will the start reading from this buffer and progressively
2062 fetch information from the resource, calling the read() function of the
2063 handler until the resource is exhausted</li>
2064 <li>if an encoding change is detected it will be installed on the input
2065 buffer, providing buffering and efficient use of the conversion
2066 routines</li>
2067 <li>once the parser has finished, the close() function of the handler is
2068 called once and the Input buffer and associed resources are
2069 deallocated.</li>
2070</ol>
2071
2072<p>The user defined callbacks are checked first to allow overriding of the
2073default libxml I/O routines.</p>
2074
2075<h3><a name="basic">The basic buffer type</a></h3>
2076
2077<p>All the buffer manipulation handling is done using the
2078<code>xmlBuffer</code> type define in <code><a
2079href="http://xmlsoft.org/html/libxml-tree.html">tree.h</a> </code>which is a
2080resizable memory buffer. The buffer allocation strategy can be selected to be
2081either best-fit or use an exponential doubling one (CPU vs. memory use
2082tradeoff). The values are <code>XML_BUFFER_ALLOC_EXACT</code> and
2083<code>XML_BUFFER_ALLOC_DOUBLEIT</code>, and can be set individually or on a
2084system wide basis using <code>xmlBufferSetAllocationScheme()</code>. A number
2085of functions allows to manipulate buffers with names starting with the
2086<code>xmlBuffer...</code> prefix.</p>
2087
2088<h3><a name="Input">Input I/O handlers</a></h3>
2089
2090<p>An Input I/O handler is a simple structure
2091<code>xmlParserInputBuffer</code> containing a context associated to the
2092resource (file descriptor, or pointer to a protocol handler), the read() and
2093close() callbacks to use and an xmlBuffer. And extra xmlBuffer and a charset
2094encoding handler are also present to support charset conversion when
2095needed.</p>
2096
2097<h3><a name="Output">Output I/O handlers</a></h3>
2098
2099<p>An Output handler <code>xmlOutputBuffer</code> is completely similar to an
2100Input one except the callbacks are write() and close().</p>
2101
2102<h3><a name="entities">The entities loader</a></h3>
2103
2104<p>The entity loader resolves requests for new entities and create inputs for
2105the parser. Creating an input from a filename or an URI string is done
2106through the xmlNewInputFromFile() routine. The default entity loader do not
2107handle the PUBLIC identifier associated with an entity (if any). So it just
2108calls xmlNewInputFromFile() with the SYSTEM identifier (which is mandatory in
2109XML).</p>
2110
2111<p>If you want to hook up a catalog mechanism then you simply need to
2112override the default entity loader, here is an example:</p>
2113<pre>#include &lt;libxml/xmlIO.h&gt;
2114
2115xmlExternalEntityLoader defaultLoader = NULL;
2116
2117xmlParserInputPtr
2118xmlMyExternalEntityLoader(const char *URL, const char *ID,
2119 xmlParserCtxtPtr ctxt) {
2120 xmlParserInputPtr ret;
2121 const char *fileID = NULL;
2122 /* lookup for the fileID depending on ID */
2123
2124 ret = xmlNewInputFromFile(ctxt, fileID);
2125 if (ret != NULL)
2126 return(ret);
2127 if (defaultLoader != NULL)
2128 ret = defaultLoader(URL, ID, ctxt);
2129 return(ret);
2130}
2131
2132int main(..) {
2133 ...
2134
2135 /*
2136 * Install our own entity loader
2137 */
2138 defaultLoader = xmlGetExternalEntityLoader();
2139 xmlSetExternalEntityLoader(xmlMyExternalEntityLoader);
2140
2141 ...
2142}</pre>
2143
2144<h3><a name="Example2">Example of customized I/O</a></h3>
2145
2146<p>This example come from <a href="http://xmlsoft.org/messages/0708.html">a
2147real use case</a>, xmlDocDump() closes the FILE * passed by the application
2148and this was a problem. The <a
2149href="http://xmlsoft.org/messages/0711.html">solution</a> was to redefine a
2150new output handler with the closing call deactivated:</p>
2151<ol>
2152 <li>First define a new I/O ouput allocator where the output don't close the
2153 file:
2154 <pre>xmlOutputBufferPtr
2155xmlOutputBufferCreateOwn(FILE *file, xmlCharEncodingHandlerPtr encoder) {
2156    xmlOutputBufferPtr ret;
2157    
2158    if (xmlOutputCallbackInitialized == 0)
2159        xmlRegisterDefaultOutputCallbacks();
2160
2161    if (file == NULL) return(NULL);
2162    ret = xmlAllocOutputBuffer(encoder);
2163    if (ret != NULL) {
2164        ret-&gt;context = file;
2165        ret-&gt;writecallback = xmlFileWrite;
2166        ret-&gt;closecallback = NULL; /* No close callback */
2167    }
2168    return(ret); <br>
2169
2170
2171
Daniel Veillard9c466822001-10-25 12:03:39 +0000[diff] [blame]2172
2173
Daniel Veillardc6271d22001-10-27 07:50:58 +0000[diff] [blame]2174
Daniel Veillard51095312001-10-28 18:51:57 +0000[diff] [blame]2175
Daniel Veillard52dcab32001-10-30 12:51:17 +0000[diff] [blame]2176
Daniel Veillarded421aa2001-11-04 21:22:45 +0000[diff] [blame]2177
Daniel Veillard43d3f612001-11-10 11:57:23 +0000[diff] [blame]2178
Daniel Veillarda4871052001-11-26 13:19:48 +0000[diff] [blame^]2179
Daniel Veillardb8cfbd12001-10-25 10:53:28 +0000[diff] [blame]2180} </pre>
2181 </li>
2182 <li>And then use it to save the document:
2183 <pre>FILE *f;
2184xmlOutputBufferPtr output;
2185xmlDocPtr doc;
2186int res;
2187
2188f = ...
2189doc = ....
2190
2191output = xmlOutputBufferCreateOwn(f, NULL);
2192res = xmlSaveFileTo(output, doc, NULL);
2193 </pre>
2194 </li>
2195</ol>
2196
2197<h2><a name="Catalog">Catalog support</a></h2>
2198
2199<p>Table of Content:</p>
2200<ol>
2201 <li><a href="General2">General overview</a></li>
2202 <li><a href="#definition">The definition</a></li>
2203 <li><a href="#Simple">Using catalogs</a></li>
2204 <li><a href="#Some">Some examples</a></li>
2205 <li><a href="#reference">How to tune catalog usage</a></li>
2206 <li><a href="#validate">How to debug catalog processing</a></li>
2207 <li><a href="#Declaring">How to create and maintain catalogs</a></li>
2208 <li><a href="#implemento">The implementor corner quick review of the
2209 API</a></li>
2210 <li><a href="#Other">Other resources</a></li>
2211</ol>
2212
2213<h3><a name="General2">General overview</a></h3>
2214
2215<p>What is a catalog? Basically it's a lookup mechanism used when an entity
2216(a file or a remote resource) references another entity. The catalog lookup
2217is inserted between the moment the reference is recognized by the software
2218(XML parser, stylesheet processing, or even images referenced for inclusion
2219in a rendering) and the time where loading that resource is actually
2220started.</p>
2221
2222<p>It is basically used for 3 things:</p>
2223<ul>
2224 <li>mapping from "logical" names, the public identifiers and a more
2225 concrete name usable for download (and URI). For example it can associate
2226 the logical name
2227 <p>"-//OASIS//DTD DocBook XML V4.1.2//EN"</p>
2228 <p>of the DocBook 4.1.2 XML DTD with the actual URL where it can be
2229 downloaded</p>
2230 <p>http://www.oasis-open.org/docbook/xml/4.1.2/docbookx.dtd</p>
2231 </li>
2232 <li>remapping from a given URL to another one, like an HTTP indirection
2233 saying that
2234 <p>"http://www.oasis-open.org/committes/tr.xsl"</p>
2235 <p>should really be looked at</p>
2236 <p>"http://www.oasis-open.org/committes/entity/stylesheets/base/tr.xsl"</p>
2237 </li>
2238 <li>providing a local cache mechanism allowing to load the entities
2239 associated to public identifiers or remote resources, this is a really
2240 important feature for any significant deployment of XML or SGML since it
2241 allows to avoid the aleas and delays associated to fetching remote
2242 resources.</li>
2243</ul>
2244
2245<h3><a name="definition">The definitions</a></h3>
2246
2247<p>Libxml, as of 2.4.3 implements 2 kind of catalogs:</p>
2248<ul>
2249 <li>the older SGML catalogs, the official spec is SGML Open Technical
2250 Resolution TR9401:1997, but is better understood by reading <a
2251 href="http://www.jclark.com/sp/catalog.htm">the SP Catalog page</a> from
2252 James Clark. This is relatively old and not the preferred mode of
2253 operation of libxml.</li>
2254 <li><a href="http://www.oasis-open.org/committees/entity/spec.html">XML
2255 Catalogs</a>
2256 is far more flexible, more recent, uses an XML syntax and should scale
2257 quite better. This is the default option of libxml.</li>
2258</ul>
2259
2260<p></p>
2261
2262<h3><a name="Simple">Using catalog</a></h3>
2263
2264<p>In a normal environment libxml will by default check the presence of a
2265catalog in /etc/xml/catalog, and assuming it has been correctly populated,
2266the processing is completely transparent to the document user. To take a
2267concrete example, suppose you are authoring a DocBook document, this one
2268starts with the following DOCTYPE definition:</p>
2269<pre>&lt;?xml version='1.0'?&gt;
2270&lt;!DOCTYPE book PUBLIC "-//Norman Walsh//DTD DocBk XML V3.1.4//EN"
2271 "http://nwalsh.com/docbook/xml/3.1.4/db3xml.dtd"&gt;</pre>
2272
2273<p>When validating the document with libxml, the catalog will be
2274automatically consulted to lookup the public identifier "-//Norman Walsh//DTD
2275DocBk XML V3.1.4//EN" and the system identifier
2276"http://nwalsh.com/docbook/xml/3.1.4/db3xml.dtd", and if these entities have
2277been installed on your system and the catalogs actually point to them, libxml
2278will fetch them from the local disk.</p>
2279
2280<p style="font-size: 10pt"><strong>Note</strong>: Really don't use this
2281DOCTYPE example it's a really old version, but is fine as an example.</p>
2282
2283<p>Libxml will check the catalog each time that it is requested to load an
2284entity, this includes DTD, external parsed entities, stylesheets, etc ... If
2285your system is correctly configured all the authoring phase and processing
2286should use only local files, even if your document stays portable because it
2287uses the canonical public and system ID, referencing the remote document.</p>
2288
2289<h3><a name="Some">Some examples:</a></h3>
2290
2291<p>Here is a couple of fragments from XML Catalogs used in libxml early
2292regression tests in <code>test/catalogs</code> :</p>
2293<pre>&lt;?xml version="1.0"?&gt;
2294&lt;!DOCTYPE catalog PUBLIC
2295 "-//OASIS//DTD Entity Resolution XML Catalog V1.0//EN"
2296 "http://www.oasis-open.org/committees/entity/release/1.0/catalog.dtd"&gt;
2297&lt;catalog xmlns="urn:oasis:names:tc:entity:xmlns:xml:catalog"&gt;
2298 &lt;public publicId="-//OASIS//DTD DocBook XML V4.1.2//EN"
2299 uri="http://www.oasis-open.org/docbook/xml/4.1.2/docbookx.dtd"/&gt;
2300...</pre>
2301
2302<p>This is the beginning of a catalog for DocBook 4.1.2, XML Catalogs are
2303written in XML, there is a specific namespace for catalog elements
2304"urn:oasis:names:tc:entity:xmlns:xml:catalog". The first entry in this
2305catalog is a <code>public</code> mapping it allows to associate a Public
2306Identifier with an URI.</p>
2307<pre>...
2308 &lt;rewriteSystem systemIdStartString="http://www.oasis-open.org/docbook/"
2309 rewritePrefix="file:///usr/share/xml/docbook/"/&gt;
2310...</pre>
2311
2312<p>A <code>rewriteSystem</code> is a very powerful instruction, it says that
2313any URI starting with a given prefix should be looked at another URI
2314constructed by replacing the prefix with an new one. In effect this acts like
2315a cache system for a full area of the Web. In practice it is extremely useful
2316with a file prefix if you have installed a copy of those resources on your
2317local system.</p>
2318<pre>...
2319&lt;delegatePublic publicIdStartString="-//OASIS//DTD XML Catalog //"
2320 catalog="file:///usr/share/xml/docbook.xml"/&gt;
2321&lt;delegatePublic publicIdStartString="-//OASIS//ENTITIES DocBook XML"
2322 catalog="file:///usr/share/xml/docbook.xml"/&gt;
2323&lt;delegatePublic publicIdStartString="-//OASIS//DTD DocBook XML"
2324 catalog="file:///usr/share/xml/docbook.xml"/&gt;
2325&lt;delegateSystem systemIdStartString="http://www.oasis-open.org/docbook/"
2326 catalog="file:///usr/share/xml/docbook.xml"/&gt;
2327&lt;delegateURI uriStartString="http://www.oasis-open.org/docbook/"
2328 catalog="file:///usr/share/xml/docbook.xml"/&gt;
2329...</pre>
2330
2331<p>Delegation is the core features which allows to build a tree of catalogs,
2332easier to maintain than a single catalog, based on Public Identifier, System
2333Identifier or URI prefixes it instructs the catalog software to look up
2334entries in another resource. This feature allow to build hierarchies of
2335catalogs, the set of entries presented should be sufficient to redirect the
2336resolution of all DocBook references to the specific catalog in
2337<code>/usr/share/xml/docbook.xml</code> this one in turn could delegate all
2338references for DocBook 4.2.1 to a specific catalog installed at the same time
2339as the DocBook resources on the local machine.</p>
2340
2341<h3><a name="reference">How to tune catalog usage:</a></h3>
2342
2343<p>The user can change the default catalog behaviour by redirecting queries
2344to its own set of catalogs, this can be done by setting the
2345<code>XML_CATALOG_FILES</code> environment variable to a list of catalogs, an
2346empty one should deactivate loading the default <code>/etc/xml/catalog</code>
2347default catalog</p>
2348
2349<h3><a name="validate">How to debug catalog processing:</a></h3>
2350
2351<p>Setting up the <code>XML_DEBUG_CATALOG</code> environment variable will
2352make libxml output debugging informations for each catalog operations, for
2353example:</p>
2354<pre>orchis:~/XML -&gt; xmllint --memory --noout test/ent2
2355warning: failed to load external entity "title.xml"
2356orchis:~/XML -&gt; export XML_DEBUG_CATALOG=
2357orchis:~/XML -&gt; xmllint --memory --noout test/ent2
2358Failed to parse catalog /etc/xml/catalog
2359Failed to parse catalog /etc/xml/catalog
2360warning: failed to load external entity "title.xml"
2361Catalogs cleanup
2362orchis:~/XML -&gt; </pre>
2363
2364<p>The test/ent2 references an entity, running the parser from memory makes
2365the base URI unavailable and the the "title.xml" entity cannot be loaded.
2366Setting up the debug environment variable allows to detect that an attempt is
2367made to load the <code>/etc/xml/catalog</code> but since it's not present the
2368resolution fails.</p>
2369
2370<p>But the most advanced way to debug XML catalog processing is to use the
2371<strong>xmlcatalog</strong> command shipped with libxml2, it allows to load
2372catalogs and make resolution queries to see what is going on. This is also
2373used for the regression tests:</p>
2374<pre>orchis:~/XML -&gt; ./xmlcatalog test/catalogs/docbook.xml \
2375 "-//OASIS//DTD DocBook XML V4.1.2//EN"
2376http://www.oasis-open.org/docbook/xml/4.1.2/docbookx.dtd
2377orchis:~/XML -&gt; </pre>
2378
2379<p>For debugging what is going on, adding one -v flags increase the verbosity
2380level to indicate the processing done (adding a second flag also indicate
2381what elements are recognized at parsing):</p>
2382<pre>orchis:~/XML -&gt; ./xmlcatalog -v test/catalogs/docbook.xml \
2383 "-//OASIS//DTD DocBook XML V4.1.2//EN"
2384Parsing catalog test/catalogs/docbook.xml's content
2385Found public match -//OASIS//DTD DocBook XML V4.1.2//EN
2386http://www.oasis-open.org/docbook/xml/4.1.2/docbookx.dtd
2387Catalogs cleanup
2388orchis:~/XML -&gt; </pre>
2389
2390<p>A shell interface is also available to debug and process multiple queries
2391(and for regression tests):</p>
2392<pre>orchis:~/XML -&gt; ./xmlcatalog -shell test/catalogs/docbook.xml \
2393 "-//OASIS//DTD DocBook XML V4.1.2//EN"
2394&gt; help
2395Commands available:
2396public PublicID: make a PUBLIC identifier lookup
2397system SystemID: make a SYSTEM identifier lookup
2398resolve PublicID SystemID: do a full resolver lookup
2399add 'type' 'orig' 'replace' : add an entry
2400del 'values' : remove values
2401dump: print the current catalog state
2402debug: increase the verbosity level
2403quiet: decrease the verbosity level
2404exit: quit the shell
2405&gt; public "-//OASIS//DTD DocBook XML V4.1.2//EN"
2406http://www.oasis-open.org/docbook/xml/4.1.2/docbookx.dtd
2407&gt; quit
2408orchis:~/XML -&gt; </pre>
2409
2410<p>This should be sufficient for most debugging purpose, this was actually
2411used heavily to debug the XML Catalog implementation itself.</p>
2412
2413<h3><a name="Declaring">How to create and maintain</a> catalogs:</h3>
2414
2415<p>Basically XML Catalogs are XML files, you can either use XML tools to
2416manage them or use <strong>xmlcatalog</strong> for this. The basic step is
2417to create a catalog the -create option provide this facility:</p>
2418<pre>orchis:~/XML -&gt; ./xmlcatalog --create tst.xml
2419&lt;?xml version="1.0"?&gt;
2420&lt;!DOCTYPE catalog PUBLIC "-//OASIS//DTD Entity Resolution XML Catalog V1.0//EN"
2421 "http://www.oasis-open.org/committees/entity/release/1.0/catalog.dtd"&gt;
2422&lt;catalog xmlns="urn:oasis:names:tc:entity:xmlns:xml:catalog"/&gt;
2423orchis:~/XML -&gt; </pre>
2424
2425<p>By default xmlcatalog does not overwrite the original catalog and save the
2426result on the standard output, this can be overridden using the -noout
2427option. The <code>-add</code> command allows to add entries in the
2428catalog:</p>
2429<pre>orchis:~/XML -&gt; ./xmlcatalog --noout --create --add "public" \
2430 "-//OASIS//DTD DocBook XML V4.1.2//EN" \
2431 http://www.oasis-open.org/docbook/xml/4.1.2/docbookx.dtd tst.xml
2432orchis:~/XML -&gt; cat tst.xml
2433&lt;?xml version="1.0"?&gt;
2434&lt;!DOCTYPE catalog PUBLIC "-//OASIS//DTD Entity Resolution XML Catalog V1.0//EN" \
2435 "http://www.oasis-open.org/committees/entity/release/1.0/catalog.dtd"&gt;
2436&lt;catalog xmlns="urn:oasis:names:tc:entity:xmlns:xml:catalog"&gt;
2437&lt;public publicId="-//OASIS//DTD DocBook XML V4.1.2//EN"
2438 uri="http://www.oasis-open.org/docbook/xml/4.1.2/docbookx.dtd"/&gt;
2439&lt;/catalog&gt;
2440orchis:~/XML -&gt; </pre>
2441
2442<p>The <code>-add</code> option will always take 3 parameters even if some of
2443the XML Catalog constructs (like nextCatalog) will have only a single
2444argument, just pass a third empty string, it will be ignored.</p>
2445
2446<p>Similarly the <code>-del</code> option remove matching entries from the
2447catalog:</p>
2448<pre>orchis:~/XML -&gt; ./xmlcatalog --del \
2449 "http://www.oasis-open.org/docbook/xml/4.1.2/docbookx.dtd" tst.xml
2450&lt;?xml version="1.0"?&gt;
2451&lt;!DOCTYPE catalog PUBLIC "-//OASIS//DTD Entity Resolution XML Catalog V1.0//EN"
2452 "http://www.oasis-open.org/committees/entity/release/1.0/catalog.dtd"&gt;
2453&lt;catalog xmlns="urn:oasis:names:tc:entity:xmlns:xml:catalog"/&gt;
2454orchis:~/XML -&gt; </pre>
2455
2456<p>The catalog is now empty. Note that the matching of <code>-del</code> is
2457exact and would have worked in a similar fashion with the Public ID
2458string.</p>
2459
2460<p>This is rudimentary but should be sufficient to manage a not too complex
2461catalog tree of resources.</p>
2462
2463<h3><a name="implemento">The implementor corner quick review of the
2464API:</a></h3>
2465
2466<p>First, and like for every other module of libxml, there is an
2467automatically generated <a href="html/libxml-catalog.html">API page for
2468catalog support</a>.</p>
2469
2470<p>The header for the catalog interfaces should be included as:</p>
2471<pre>#include &lt;libxml/catalog.h&gt;</pre>
2472
2473<p>The API is voluntarily kept very simple. First it is not obvious that
2474applications really need access to it since it is the default behaviour of
2475libxml (Note: it is possible to completely override libxml default catalog by
2476using <a href="html/libxml-parser.html">xmlSetExternalEntityLoader</a> to
2477plug an application specific resolver).</p>
2478
2479<p>Basically libxml support 2 catalog lists:</p>
2480<ul>
2481 <li>the default one, global shared by all the application</li>
2482 <li>a per-document catalog, this one is built if the document uses the
2483 <code>oasis-xml-catalog</code> PIs to specify its own catalog list, it is
2484 associated to the parser context and destroyed when the parsing context
2485 is destroyed.</li>
2486</ul>
2487
2488<p>the document one will be used first if it exists.</p>
2489
2490<h4>Initialization routines:</h4>
2491
2492<p>xmlInitializeCatalog(), xmlLoadCatalog() and xmlLoadCatalogs() should be
2493used at startup to initialize the catalog, if the catalog should be
2494initialized with specific values xmlLoadCatalog() or xmlLoadCatalogs()
2495should be called before xmlInitializeCatalog() which would otherwise do a
2496default initialization first.</p>
2497
2498<p>The xmlCatalogAddLocal() call is used by the parser to grow the document
2499own catalog list if needed.</p>
2500
2501<h4>Preferences setup:</h4>
2502
2503<p>The XML Catalog spec requires the possibility to select default
2504preferences between public and system delegation,
2505xmlCatalogSetDefaultPrefer() allows this, xmlCatalogSetDefaults() and
2506xmlCatalogGetDefaults() allow to control if XML Catalogs resolution should
2507be forbidden, allowed for global catalog, for document catalog or both, the
2508default is to allow both.</p>
2509
2510<p>And of course xmlCatalogSetDebug() allows to generate debug messages
2511(through the xmlGenericError() mechanism).</p>
2512
2513<h4>Querying routines:</h4>
2514
2515<p>xmlCatalogResolve(), xmlCatalogResolveSystem(), xmlCatalogResolvePublic()
2516and xmlCatalogResolveURI() are relatively explicit if you read the XML
2517Catalog specification they correspond to section 7 algorithms, they should
2518also work if you have loaded an SGML catalog with a simplified semantic.</p>
2519
2520<p>xmlCatalogLocalResolve() and xmlCatalogLocalResolveURI() are the same but
2521operate on the document catalog list</p>
2522
2523<h4>Cleanup and Miscellaneous:</h4>
2524
2525<p>xmlCatalogCleanup() free-up the global catalog, xmlCatalogFreeLocal() is
2526the per-document equivalent.</p>
2527
2528<p>xmlCatalogAdd() and xmlCatalogRemove() are used to dynamically modify the
2529first catalog in the global list, and xmlCatalogDump() allows to dump a
2530catalog state, those routines are primarily designed for xmlcatalog, I'm not
2531sure that exposing more complex interfaces (like navigation ones) would be
2532really useful.</p>
2533
2534<p>The xmlParseCatalogFile() is a function used to load XML Catalog files,
2535it's similar as xmlParseFile() except it bypass all catalog lookups, it's
2536provided because this functionality may be useful for client tools.</p>
2537
2538<h4>threaded environments:</h4>
2539
2540<p>Since the catalog tree is built progressively, some care has been taken to
2541try to avoid troubles in multithreaded environments. The code is now thread
2542safe assuming that the libxml library has been compiled with threads
2543support.</p>
2544
2545<p></p>
2546
2547<h3><a name="Other">Other resources</a></h3>
2548
2549<p>The XML Catalog specification is relatively recent so there isn't much
2550literature to point at:</p>
2551<ul>
2552 <li>You can find an good rant from Norm Walsh about <a
2553 href="http://www.arbortext.com/Think_Tank/XML_Resources/Issue_Three/issue_three.html">the
2554 need for catalogs</a>, it provides a lot of context informations even if
2555 I don't agree with everything presented.</li>
2556 <li>An <a href="http://home.ccil.org/~cowan/XML/XCatalog.html">old XML
2557 catalog proposal</a> from John Cowan</li>
2558 <li>The <a href="http://www.rddl.org/">Resource Directory Description
2559 Language</a> (RDDL) another catalog system but more oriented toward
2560 providing metadata for XML namespaces.</li>
2561 <li>the page from the OASIS Technical <a
2562 href="http://www.oasis-open.org/committees/entity/">Committee on Entity
2563 Resolution</a> who maintains XML Catalog, you will find pointers to the
2564 specification update, some background and pointers to others tools
2565 providing XML Catalog support</li>
2566 <li>I have uploaded <a href="ftp://xmlsoft.org/test/dbk412catalog.tar.gz">a
2567 mall tarball</a> containing XML Catalogs for DocBook 4.1.2 which seems to
2568 work fine for me</li>
2569 <li>The <a href="http://www.xmlsoft.org/xmlcatalog_man.html">xmlcatalog
2570 manual page</a></li>
2571</ul>
2572
2573<p>If you have suggestions for corrections or additions, simply contact
2574me:</p>
2575
2576<h2><a name="library">The parser interfaces</a></h2>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2577
2578<p>This section is directly intended to help programmers getting bootstrapped
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]2579using the XML library from the C language. It is not intended to be
2580extensive. I hope the automatically generated documents will provide the
2581completeness required, but as a separate set of documents. The interfaces of
2582the XML library are by principle low level, there is nearly zero abstraction.
2583Those interested in a higher level API should <a href="#DOM">look at
2584DOM</a>.</p>
Daniel Veillardccb09631998-10-27 06:21:04 +0000[diff] [blame]2585
Daniel Veillard9cb5ff42001-01-29 08:22:21 +0000[diff] [blame]2586<p>The <a href="html/libxml-parser.html">parser interfaces for XML</a> are
2587separated from the <a href="html/libxml-htmlparser.html">HTML parser
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]2588interfaces</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]2589
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]2590<h3><a name="Invoking">Invoking the parser : the pull method</a></h3>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2591
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]2592<p>Usually, the first thing to do is to read an XML input. The parser accepts
2593documents either from in-memory strings or from files. The functions are
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2594defined in "parser.h":</p>
Daniel Veillard10c6a8f1998-10-28 01:00:12 +0000[diff] [blame]2595<dl>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2596 <dt><code>xmlDocPtr xmlParseMemory(char *buffer, int size);</code></dt>
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]2597 <dd><p>Parse a null-terminated string containing the document.</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2598 </dd>
Daniel Veillard10c6a8f1998-10-28 01:00:12 +0000[diff] [blame]2599</dl>
2600<dl>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2601 <dt><code>xmlDocPtr xmlParseFile(const char *filename);</code></dt>
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]2602 <dd><p>Parse an XML document contained in a (possibly compressed)
2603 file.</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2604 </dd>
Daniel Veillard10c6a8f1998-10-28 01:00:12 +0000[diff] [blame]2605</dl>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2606
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]2607<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]2608failure).</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2609
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]2610<h3 id="Invoking1">Invoking the parser: the push method</h3>
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]2611
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]2612<p>In order for the application to keep the control when the document is
2613being fetched (which is common for GUI based programs) libxml provides a push
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]2614interface, too, as of version 1.8.3. Here are the interface functions:</p>
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]2615<pre>xmlParserCtxtPtr xmlCreatePushParserCtxt(xmlSAXHandlerPtr sax,
2616 void *user_data,
2617 const char *chunk,
2618 int size,
2619 const char *filename);
2620int xmlParseChunk (xmlParserCtxtPtr ctxt,
2621 const char *chunk,
2622 int size,
2623 int terminate);</pre>
2624
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]2625<p>and here is a simple example showing how to use the interface:</p>
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]2626<pre> FILE *f;
2627
2628 f = fopen(filename, "r");
2629 if (f != NULL) {
2630 int res, size = 1024;
2631 char chars[1024];
2632 xmlParserCtxtPtr ctxt;
2633
2634 res = fread(chars, 1, 4, f);
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]2635 if (res &gt; 0) {
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]2636 ctxt = xmlCreatePushParserCtxt(NULL, NULL,
2637 chars, res, filename);
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]2638 while ((res = fread(chars, 1, size, f)) &gt; 0) {
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]2639 xmlParseChunk(ctxt, chars, res, 0);
2640 }
2641 xmlParseChunk(ctxt, chars, 0, 1);
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]2642 doc = ctxt-&gt;myDoc;
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]2643 xmlFreeParserCtxt(ctxt);
2644 }
2645 }</pre>
2646
Daniel Veillardec70e912001-02-26 20:10:45 +0000[diff] [blame]2647<p>The HTML parser embedded into libxml also has a push interface; the
2648functions are just prefixed by "html" rather than "xml".</p>
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]2649
2650<h3 id="Invoking2">Invoking the parser: the SAX interface</h3>
2651
Daniel Veillardec70e912001-02-26 20:10:45 +0000[diff] [blame]2652<p>The tree-building interface makes the parser memory-hungry, first loading
2653the document in memory and then building the tree itself. Reading a document
2654without building the tree is possible using the SAX interfaces (see SAX.h and
2655<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]2656Henstridge's documentation</a>). Note also that the push interface can be
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]2657limited to SAX: just use the two first arguments of
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]2658<code>xmlCreatePushParserCtxt()</code>.</p>
Daniel Veillardccb09631998-10-27 06:21:04 +0000[diff] [blame]2659
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]2660<h3><a name="Building">Building a tree from scratch</a></h3>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2661
2662<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]2663there is a set of functions dedicated to building new elements. (These are
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]2664also described in &lt;libxml/tree.h&gt;.) For example, here is a piece of
2665code that produces the XML document used in the previous examples:</p>
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]2666<pre> #include &lt;libxml/tree.h&gt;
Daniel Veillard361d8452000-04-03 19:48:13 +0000[diff] [blame]2667 xmlDocPtr doc;
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]2668 xmlNodePtr tree, subtree;
2669
2670 doc = xmlNewDoc("1.0");
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]2671 doc-&gt;children = xmlNewDocNode(doc, NULL, "EXAMPLE", NULL);
2672 xmlSetProp(doc-&gt;children, "prop1", "gnome is great");
2673 xmlSetProp(doc-&gt;children, "prop2", "&amp; linux too");
2674 tree = xmlNewChild(doc-&gt;children, NULL, "head", NULL);
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]2675 subtree = xmlNewChild(tree, NULL, "title", "Welcome to Gnome");
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]2676 tree = xmlNewChild(doc-&gt;children, NULL, "chapter", NULL);
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]2677 subtree = xmlNewChild(tree, NULL, "title", "The Linux adventure");
2678 subtree = xmlNewChild(tree, NULL, "p", "bla bla bla ...");
2679 subtree = xmlNewChild(tree, NULL, "image", NULL);
2680 xmlSetProp(subtree, "href", "linus.gif");</pre>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2681
2682<p>Not really rocket science ...</p>
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]2683
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]2684<h3><a name="Traversing">Traversing the tree</a></h3>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2685
Daniel Veillard9cb5ff42001-01-29 08:22:21 +0000[diff] [blame]2686<p>Basically by <a href="html/libxml-tree.html">including "tree.h"</a> your
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]2687code has access to the internal structure of all the elements of the tree.
2688The names should be somewhat simple like <strong>parent</strong>,
Daniel Veillard306be992000-07-03 12:38:45 +0000[diff] [blame]2689<strong>children</strong>, <strong>next</strong>, <strong>prev</strong>,
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]2690<strong>properties</strong>, etc... For example, still with the previous
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]2691example:</p>
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]2692<pre><code>doc-&gt;children-&gt;children-&gt;children</code></pre>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2693
2694<p>points to the title element,</p>
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]2695<pre>doc-&gt;children-&gt;children-&gt;next-&gt;children-&gt;children</pre>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2696
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]2697<p>points to the text node containing the chapter title "The Linux
2698adventure".</p>
Daniel Veillard10c6a8f1998-10-28 01:00:12 +0000[diff] [blame]2699
Daniel Veillardb24054a1999-12-18 15:32:46 +0000[diff] [blame]2700<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]2701present before the document root, so <code>doc-&gt;children</code> may point
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]2702to an element which is not the document Root Element; a function
Daniel Veillard5cb5ab81999-12-21 15:35:29 +0000[diff] [blame]2703<code>xmlDocGetRootElement()</code> was added for this purpose.</p>
Daniel Veillardb24054a1999-12-18 15:32:46 +0000[diff] [blame]2704
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]2705<h3><a name="Modifying">Modifying the tree</a></h3>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2706
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]2707<p>Functions are provided for reading and writing the document content. Here
Daniel Veillard9cb5ff42001-01-29 08:22:21 +0000[diff] [blame]2708is an excerpt from the <a href="html/libxml-tree.html">tree API</a>:</p>
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]2709<dl>
Daniel Veillarddd6b3671999-09-23 22:19:22 +0000[diff] [blame]2710 <dt><code>xmlAttrPtr xmlSetProp(xmlNodePtr node, const xmlChar *name, const
2711 xmlChar *value);</code></dt>
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]2712 <dd><p>This sets (or changes) an attribute carried by an ELEMENT node.
2713 The value can be NULL.</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2714 </dd>
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]2715</dl>
2716<dl>
Daniel Veillarddd6b3671999-09-23 22:19:22 +0000[diff] [blame]2717 <dt><code>const xmlChar *xmlGetProp(xmlNodePtr node, const xmlChar
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2718 *name);</code></dt>
Daniel Veillardc92c3042000-09-29 02:42:04 +0000[diff] [blame]2719 <dd><p>This function returns a pointer to new copy of the property
2720 content. Note that the user must deallocate the result.</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2721 </dd>
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]2722</dl>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2723
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]2724<p>Two functions are provided for reading and writing the text associated
2725with elements:</p>
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]2726<dl>
Daniel Veillarddd6b3671999-09-23 22:19:22 +0000[diff] [blame]2727 <dt><code>xmlNodePtr xmlStringGetNodeList(xmlDocPtr doc, const xmlChar
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2728 *value);</code></dt>
Daniel Veillardec70e912001-02-26 20:10:45 +0000[diff] [blame]2729 <dd><p>This function takes an "external" string and converts it to one
2730 text node or possibly to a list of entity and text nodes. All
2731 non-predefined entity references like &amp;Gnome; will be stored
2732 internally as entity nodes, hence the result of the function may not be
2733 a single node.</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2734 </dd>
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]2735</dl>
2736<dl>
Daniel Veillarddd6b3671999-09-23 22:19:22 +0000[diff] [blame]2737 <dt><code>xmlChar *xmlNodeListGetString(xmlDocPtr doc, xmlNodePtr list, int
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2738 inLine);</code></dt>
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]2739 <dd><p>This function is the inverse of
2740 <code>xmlStringGetNodeList()</code>. It generates a new string
2741 containing the content of the text and entity nodes. Note the extra
2742 argument inLine. If this argument is set to 1, the function will expand
2743 entity references. For example, instead of returning the &amp;Gnome;
2744 XML encoding in the string, it will substitute it with its value (say,
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]2745 "GNU Network Object Model Environment").</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2746 </dd>
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]2747</dl>
Daniel Veillard10c6a8f1998-10-28 01:00:12 +0000[diff] [blame]2748
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]2749<h3><a name="Saving">Saving a tree</a></h3>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2750
2751<p>Basically 3 options are possible:</p>
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]2752<dl>
Daniel Veillarddd6b3671999-09-23 22:19:22 +0000[diff] [blame]2753 <dt><code>void xmlDocDumpMemory(xmlDocPtr cur, xmlChar**mem, int
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2754 *size);</code></dt>
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]2755 <dd><p>Returns a buffer into which the document has been saved.</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2756 </dd>
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]2757</dl>
2758<dl>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2759 <dt><code>extern void xmlDocDump(FILE *f, xmlDocPtr doc);</code></dt>
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]2760 <dd><p>Dumps a document to an open file descriptor.</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2761 </dd>
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]2762</dl>
2763<dl>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2764 <dt><code>int xmlSaveFile(const char *filename, xmlDocPtr cur);</code></dt>
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]2765 <dd><p>Saves the document to a file. In this case, the compression
2766 interface is triggered if it has been turned on.</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2767 </dd>
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]2768</dl>
Daniel Veillard10c6a8f1998-10-28 01:00:12 +0000[diff] [blame]2769
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]2770<h3><a name="Compressio">Compression</a></h3>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2771
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]2772<p>The library transparently handles compression when doing file-based
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]2773accesses. The level of compression on saves can be turned on either globally
2774or individually for one file:</p>
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]2775<dl>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2776 <dt><code>int xmlGetDocCompressMode (xmlDocPtr doc);</code></dt>
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]2777 <dd><p>Gets the document compression ratio (0-9).</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2778 </dd>
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]2779</dl>
2780<dl>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2781 <dt><code>void xmlSetDocCompressMode (xmlDocPtr doc, int mode);</code></dt>
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]2782 <dd><p>Sets the document compression ratio.</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2783 </dd>
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]2784</dl>
2785<dl>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2786 <dt><code>int xmlGetCompressMode(void);</code></dt>
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]2787 <dd><p>Gets the default compression ratio.</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2788 </dd>
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]2789</dl>
2790<dl>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2791 <dt><code>void xmlSetCompressMode(int mode);</code></dt>
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]2792 <dd><p>Sets the default compression ratio.</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2793 </dd>
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]2794</dl>
2795
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]2796<h2><a name="Entities">Entities or no entities</a></h2>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]2797
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]2798<p>Entities in principle are similar to simple C macros. An entity defines an
2799abbreviation for a given string that you can reuse many times throughout the
2800content of your document. Entities are especially useful when a given string
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]2801may occur frequently within a document, or to confine the change needed to a
2802document to a restricted area in the internal subset of the document (at the
2803beginning). Example:</p>
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]2804<pre>1 &lt;?xml version="1.0"?&gt;
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]28052 &lt;!DOCTYPE EXAMPLE SYSTEM "example.dtd" [
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]28063 &lt;!ENTITY xml "Extensible Markup Language"&gt;
28074 ]&gt;
28085 &lt;EXAMPLE&gt;
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]28096 &amp;xml;
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]28107 &lt;/EXAMPLE&gt;</pre>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]2811
2812<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]2813its name with '&amp;' and following it by ';' without any spaces added. There
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]2814are 5 predefined entities in libxml allowing you to escape charaters with
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]2815predefined meaning in some parts of the xml document content:
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]2816<strong>&amp;lt;</strong> for the character '&lt;', <strong>&amp;gt;</strong>
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]2817for the character '&gt;', <strong>&amp;apos;</strong> for the character ''',
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]2818<strong>&amp;quot;</strong> for the character '"', and
2819<strong>&amp;amp;</strong> for the character '&amp;'.</p>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]2820
2821<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]2822substitute an entity's content so that you can see the replacement text in
2823your application. Or you may prefer to keep entity references as such in the
2824content to be able to save the document back without losing this usually
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]2825precious information (if the user went through the pain of explicitly
2826defining entities, he may have a a rather negative attitude if you blindly
2827susbtitute them as saving time). The <a
Daniel Veillard9cb5ff42001-01-29 08:22:21 +0000[diff] [blame]2828href="html/libxml-parser.html#XMLSUBSTITUTEENTITIESDEFAULT">xmlSubstituteEntitiesDefault()</a>
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]2829function allows you to check and change the behaviour, which is to not
2830substitute entities by default.</p>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]2831
2832<p>Here is the DOM tree built by libxml for the previous document in the
2833default case:</p>
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]2834<pre>/gnome/src/gnome-xml -&gt; ./xmllint --debug test/ent1
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]2835DOCUMENT
2836version=1.0
2837 ELEMENT EXAMPLE
2838 TEXT
2839 content=
2840 ENTITY_REF
2841 INTERNAL_GENERAL_ENTITY xml
2842 content=Extensible Markup Language
2843 TEXT
2844 content=</pre>
2845
2846<p>And here is the result when substituting entities:</p>
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]2847<pre>/gnome/src/gnome-xml -&gt; ./tester --debug --noent test/ent1
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]2848DOCUMENT
2849version=1.0
2850 ELEMENT EXAMPLE
2851 TEXT
2852 content= Extensible Markup Language</pre>
2853
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]2854<p>So, entities or no entities? Basically, it depends on your use case. I
2855suggest that you keep the non-substituting default behaviour and avoid using
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]2856entities in your XML document or data if you are not willing to handle the
2857entity references elements in the DOM tree.</p>
2858
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]2859<p>Note that at save time libxml enforces the conversion of the predefined
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]2860entities where necessary to prevent well-formedness problems, and will also
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]2861transparently replace those with chars (i.e. it will not generate entity
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]2862reference elements in the DOM tree or call the reference() SAX callback when
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]2863finding them in the input).</p>
2864
Daniel Veillard7b9c4b72000-08-25 16:26:50 +0000[diff] [blame]2865<p><span style="background-color: #FF0000">WARNING</span>: handling entities
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]2866on top of the libxml SAX interface is difficult!!! If you plan to use
Daniel Veillard7b9c4b72000-08-25 16:26:50 +0000[diff] [blame]2867non-predefined entities in your documents, then the learning cuvre to handle
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]2868then 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]2869strongly suggest you consider using the DOM interface instead and let libxml
Daniel Veillard8c6d6af2000-08-25 17:14:13 +0000[diff] [blame]2870deal with the complexity rather than trying to do it yourself.</p>
Daniel Veillard7b9c4b72000-08-25 16:26:50 +0000[diff] [blame]2871
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]2872<h2><a name="Namespaces">Namespaces</a></h2>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]2873
Daniel Veillardec303412000-03-24 13:41:54 +0000[diff] [blame]2874<p>The libxml library implements <a
2875href="http://www.w3.org/TR/REC-xml-names/">XML namespaces</a> support by
2876recognizing namespace contructs in the input, and does namespace lookup
2877automatically when building the DOM tree. A namespace declaration is
2878associated with an in-memory structure and all elements or attributes within
2879that namespace point to it. Hence testing the namespace is a simple and fast
2880equality operation at the user level.</p>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]2881
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]2882<p>I suggest that people using libxml use a namespace, and declare it in the
2883root element of their document as the default namespace. Then they don't need
2884to 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]2885refinement and merging of data from different sources. This doesn't increase
Daniel Veillardec70e912001-02-26 20:10:45 +0000[diff] [blame]2886the size of the XML output significantly, but significantly increases its
2887value in the long-term. Example:</p>
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]2888<pre>&lt;mydoc xmlns="http://mydoc.example.org/schemas/"&gt;
2889 &lt;elem1&gt;...&lt;/elem1&gt;
2890 &lt;elem2&gt;...&lt;/elem2&gt;
2891&lt;/mydoc&gt;</pre>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]2892
Daniel Veillardec70e912001-02-26 20:10:45 +0000[diff] [blame]2893<p>The namespace value has to be an absolute URL, but the URL doesn't have to
2894point to any existing resource on the Web. It will bind all the element and
2895atributes with that URL. I suggest to use an URL within a domain you control,
2896and that the URL should contain some kind of version information if possible.
2897For example, <code>"http://www.gnome.org/gnumeric/1.0/"</code> is a good
2898namespace scheme.</p>
Daniel Veillardec303412000-03-24 13:41:54 +0000[diff] [blame]2899
2900<p>Then when you load a file, make sure that a namespace carrying the
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]2901version-independent prefix is installed on the root element of your document,
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]2902and if the version information don't match something you know, warn the user
2903and 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]2904namespace checking on the prefix value. &lt;foo:text&gt; may be exactly the
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]2905same as &lt;bar:text&gt; in another document. What really matters is the URI
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]2906associated with the element or the attribute, not the prefix string (which is
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]2907just a shortcut for the full URI). In libxml, element and attributes have an
Daniel Veillardec303412000-03-24 13:41:54 +0000[diff] [blame]2908<code>ns</code> field pointing to an xmlNs structure detailing the namespace
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]2909prefix and its URI.</p>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]2910
2911<p>@@Interfaces@@</p>
2912
2913<p>@@Examples@@</p>
2914
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]2915<p>Usually people object to using namespaces together with validity checking.
2916I will try to make sure that using namespaces won't break validity checking,
2917so even if you plan to use or currently are using validation I strongly
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]2918suggest adding namespaces to your document. A default namespace scheme
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]2919<code>xmlns="http://...."</code> should not break validity even on less
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]2920flexible parsers. Using namespaces to mix and differentiate content coming
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]2921from multiple DTDs will certainly break current validation schemes. I will
2922try to provide ways to do this, but this may not be portable or
2923standardized.</p>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]2924
Daniel Veillardb8cfbd12001-10-25 10:53:28 +0000[diff] [blame]2925<h2><a name="Upgrading">Upgrading 1.x code</a></h2>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]2926
Daniel Veillardb8cfbd12001-10-25 10:53:28 +0000[diff] [blame]2927<p>Incompatible changes:</p>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]2928
Daniel Veillardb8cfbd12001-10-25 10:53:28 +0000[diff] [blame]2929<p>Version 2 of libxml is the first version introducing serious backward
2930incompatible changes. The main goals were:</p>
2931<ul>
2932 <li>a general cleanup. A number of mistakes inherited from the very early
2933 versions couldn't be changed due to compatibility constraints. Example
2934 the "childs" element in the nodes.</li>
2935 <li>Uniformization of the various nodes, at least for their header and link
2936 parts (doc, parent, children, prev, next), the goal is a simpler
2937 programming model and simplifying the task of the DOM implementors.</li>
2938 <li>better conformances to the XML specification, for example version 1.x
2939 had an heuristic to try to detect ignorable white spaces. As a result the
2940 SAX event generated were ignorableWhitespace() while the spec requires
2941 character() in that case. This also mean that a number of DOM node
2942 containing blank text may populate the DOM tree which were not present
2943 before.</li>
2944</ul>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]2945
Daniel Veillardb8cfbd12001-10-25 10:53:28 +0000[diff] [blame]2946<h3>How to fix libxml-1.x code:</h3>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]2947
Daniel Veillardb8cfbd12001-10-25 10:53:28 +0000[diff] [blame]2948<p>So client code of libxml designed to run with version 1.x may have to be
2949changed to compile against version 2.x of libxml. Here is a list of changes
2950that I have collected, they may not be sufficient, so in case you find other
2951change which are required, <a href="mailto:Daniel.Ïeillardw3.org">drop me a
2952mail</a>:</p>
2953<ol>
2954 <li>The package name have changed from libxml to libxml2, the library name
2955 is now -lxml2 . There is a new xml2-config script which should be used to
2956 select the right parameters libxml2</li>
2957 <li>Node <strong>childs</strong> field has been renamed
2958 <strong>children</strong> so s/childs/children/g should be applied
2959 (probablility of having "childs" anywere else is close to 0+</li>
2960 <li>The document don't have anymore a <strong>root</strong> element it has
2961 been replaced by <strong>children</strong> and usually you will get a
2962 list of element here. For example a Dtd element for the internal subset
2963 and it's declaration may be found in that list, as well as processing
2964 instructions or comments found before or after the document root element.
2965 Use <strong>xmlDocGetRootElement(doc)</strong> to get the root element of
2966 a document. Alternatively if you are sure to not reference Dtds nor have
2967 PIs or comments before or after the root element
2968 s/-&gt;root/-&gt;children/g will probably do it.</li>
2969 <li>The white space issue, this one is more complex, unless special case of
2970 validating parsing, the line breaks and spaces usually used for indenting
2971 and formatting the document content becomes significant. So they are
2972 reported by SAX and if your using the DOM tree, corresponding nodes are
2973 generated. Too approach can be taken:
2974 <ol>
2975 <li>lazy one, use the compatibility call
2976 <strong>xmlKeepBlanksDefault(0)</strong> but be aware that you are
2977 relying on a special (and possibly broken) set of heuristics of
2978 libxml to detect ignorable blanks. Don't complain if it breaks or
2979 make your application not 100% clean w.r.t. to it's input.</li>
2980 <li>the Right Way: change you code to accept possibly unsignificant
2981 blanks characters, or have your tree populated with weird blank text
2982 nodes. You can spot them using the comodity function
2983 <strong>xmlIsBlankNode(node)</strong> returning 1 for such blank
2984 nodes.</li>
2985 </ol>
2986 <p>Note also that with the new default the output functions don't add any
2987 extra indentation when saving a tree in order to be able to round trip
2988 (read and save) without inflating the document with extra formatting
2989 chars.</p>
2990 </li>
2991 <li>The include path has changed to $prefix/libxml/ and the includes
2992 themselves uses this new prefix in includes instructions... If you are
2993 using (as expected) the
2994 <pre>xml2-config --cflags</pre>
2995 <p>output to generate you compile commands this will probably work out of
2996 the box</p>
2997 </li>
2998 <li>xmlDetectCharEncoding takes an extra argument indicating the lenght in
2999 byte of the head of the document available for character detection.</li>
3000</ol>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]3001
Daniel Veillardb8cfbd12001-10-25 10:53:28 +0000[diff] [blame]3002<h3>Ensuring both libxml-1.x and libxml-2.x compatibility</h3>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]3003
Daniel Veillardb8cfbd12001-10-25 10:53:28 +0000[diff] [blame]3004<p>Two new version of libxml (1.8.11) and libxml2 (2.3.4) have been released
3005to allow smoth upgrade of existing libxml v1code while retaining
3006compatibility. They offers the following:</p>
3007<ol>
3008 <li>similar include naming, one should use
3009 <strong>#include&lt;libxml/...&gt;</strong> in both cases.</li>
3010 <li>similar identifiers defined via macros for the child and root fields:
3011 respectively <strong>xmlChildrenNode</strong> and
3012 <strong>xmlRootNode</strong></li>
3013 <li>a new macro <strong>LIBXML_TEST_VERSION</strong> which should be
3014 inserted once in the client code</li>
3015</ol>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]3016
Daniel Veillardb8cfbd12001-10-25 10:53:28 +0000[diff] [blame]3017<p>So the roadmap to upgrade your existing libxml applications is the
3018following:</p>
3019<ol>
3020 <li>install the libxml-1.8.8 (and libxml-devel-1.8.8) packages</li>
3021 <li>find all occurences where the xmlDoc <strong>root</strong> field is
3022 used and change it to <strong>xmlRootNode</strong></li>
3023 <li>similary find all occurences where the xmlNode <strong>childs</strong>
3024 field is used and change it to <strong>xmlChildrenNode</strong></li>
3025 <li>add a <strong>LIBXML_TEST_VERSION</strong> macro somewhere in your
3026 <strong>main()</strong> or in the library init entry point</li>
3027 <li>Recompile, check compatibility, it should still work</li>
3028 <li>Change your configure script to look first for xml2-config and fallback
3029 using xml-config . Use the --cflags and --libs ouptut of the command as
3030 the Include and Linking parameters needed to use libxml.</li>
3031 <li>install libxml2-2.3.x and libxml2-devel-2.3.x (libxml-1.8.y and
3032 libxml-devel-1.8.y can be kept simultaneously)</li>
3033 <li>remove your config.cache, relaunch your configuration mechanism, and
3034 recompile, if steps 2 and 3 were done right it should compile as-is</li>
3035 <li>Test that your application is still running correctly, if not this may
3036 be due to extra empty nodes due to formating spaces being kept in libxml2
3037 contrary to libxml1, in that case insert xmlKeepBlanksDefault(1) in your
3038 code before calling the parser (next to
3039 <strong>LIBXML_TEST_VERSION</strong> is a fine place).</li>
3040</ol>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]3041
Daniel Veillardb8cfbd12001-10-25 10:53:28 +0000[diff] [blame]3042<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]3043
Daniel Veillardb8cfbd12001-10-25 10:53:28 +0000[diff] [blame]3044<p>Let me put some emphasis on the fact that there is far more changes from
3045libxml 1.x to 2.x than the ones you may have to patch for. The overall code
3046has been considerably cleaned up and the conformance to the XML specification
3047has been drastically improved too. Don't take those changes as an excuse to
3048not upgrade, it may cost a lot on the long term ...</p>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]3049
Daniel Veillard52dcab32001-10-30 12:51:17 +0000[diff] [blame]3050<h2><a name="Thread">Thread safety</a></h2>
3051
3052<p>Starting with 2.4.7, libxml makes provisions to ensure that concurent
3053threads can safely work in parallel parsing different documents. There is
3054however a couple of things to do to ensure it:</p>
3055<ul>
3056 <li>configure the library accordingly using the --with-threads options</li>
3057 <li>call xmlInitParser() in the "main" thread before using any of the
3058 libxml API (except possibly selecting a different memory allocator)</li>
3059</ul>
3060
3061<p>Note that the thread safety cannot be ensured for multiple threads sharing
3062the same document, the locking must be done at the application level, libxml
3063exports a basic mutex and reentrant mutexes API in &lt;libxml/threads.h&gt;.
3064The parts of the library checked for thread safety are:</p>
3065<ul>
3066 <li>concurrent loading</li>
3067 <li>file access resolution</li>
3068 <li>catalog access</li>
3069 <li>catalog building</li>
3070 <li>entities lookup/accesses</li>
3071 <li>validation</li>
3072 <li>global variables per-thread override</li>
3073 <li>memory handling</li>
3074</ul>
3075
3076<p>XPath is supposed to be thread safe now, but this wasn't tested
3077seriously.</p>
3078
Daniel Veillard35008381999-10-25 13:15:52 +0000[diff] [blame]3079<h2><a name="DOM"></a><a name="Principles">DOM Principles</a></h2>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]3080
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]3081<p><a href="http://www.w3.org/DOM/">DOM</a> stands for the <em>Document
3082Object Model</em>; this is an API for accessing XML or HTML structured
3083documents. Native support for DOM in Gnome is on the way (module gnome-dom),
3084and will be based on gnome-xml. This will be a far cleaner interface to
3085manipulate XML files within Gnome since it won't expose the internal
3086structure.</p>
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]3087
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]3088<p>The current DOM implementation on top of libxml is the <a
Daniel Veillarda47fb3d2001-03-25 17:23:49 +0000[diff] [blame]3089href="http://cvs.gnome.org/lxr/source/gdome2/">gdome2 Gnome module</a>, this
3090is a full DOM interface, thanks to Paolo Casarini, check the <a
3091href="http://www.cs.unibo.it/~casarini/gdome2/">Gdome2 homepage</a> for more
3092informations.</p>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]3093
Daniel Veillard35008381999-10-25 13:15:52 +0000[diff] [blame]3094<h2><a name="Example"></a><a name="real">A real example</a></h2>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]3095
3096<p>Here is a real size example, where the actual content of the application
3097data 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]3098a proposal to keep a database of jobs related to Gnome, with an XML based
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]3099storage structure. Here is an <a href="gjobs.xml">XML encoded jobs
3100base</a>:</p>
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]3101<pre>&lt;?xml version="1.0"?&gt;
3102&lt;gjob:Helping xmlns:gjob="http://www.gnome.org/some-location"&gt;
3103 &lt;gjob:Jobs&gt;
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]3104
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]3105 &lt;gjob:Job&gt;
3106 &lt;gjob:Project ID="3"/&gt;
3107 &lt;gjob:Application&gt;GBackup&lt;/gjob:Application&gt;
3108 &lt;gjob:Category&gt;Development&lt;/gjob:Category&gt;
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]3109
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]3110 &lt;gjob:Update&gt;
3111 &lt;gjob:Status&gt;Open&lt;/gjob:Status&gt;
3112 &lt;gjob:Modified&gt;Mon, 07 Jun 1999 20:27:45 -0400 MET DST&lt;/gjob:Modified&gt;
3113 &lt;gjob:Salary&gt;USD 0.00&lt;/gjob:Salary&gt;
3114 &lt;/gjob:Update&gt;
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]3115
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]3116 &lt;gjob:Developers&gt;
3117 &lt;gjob:Developer&gt;
3118 &lt;/gjob:Developer&gt;
3119 &lt;/gjob:Developers&gt;
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]3120
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]3121 &lt;gjob:Contact&gt;
3122 &lt;gjob:Person&gt;Nathan Clemons&lt;/gjob:Person&gt;
3123 &lt;gjob:Email&gt;nathan@windsofstorm.net&lt;/gjob:Email&gt;
3124 &lt;gjob:Company&gt;
3125 &lt;/gjob:Company&gt;
3126 &lt;gjob:Organisation&gt;
3127 &lt;/gjob:Organisation&gt;
3128 &lt;gjob:Webpage&gt;
3129 &lt;/gjob:Webpage&gt;
3130 &lt;gjob:Snailmail&gt;
3131 &lt;/gjob:Snailmail&gt;
3132 &lt;gjob:Phone&gt;
3133 &lt;/gjob:Phone&gt;
3134 &lt;/gjob:Contact&gt;
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]3135
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]3136 &lt;gjob:Requirements&gt;
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]3137 The program should be released as free software, under the GPL.
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]3138 &lt;/gjob:Requirements&gt;
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]3139
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]3140 &lt;gjob:Skills&gt;
3141 &lt;/gjob:Skills&gt;
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]3142
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]3143 &lt;gjob:Details&gt;
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]3144 A GNOME based system that will allow a superuser to configure
3145 compressed and uncompressed files and/or file systems to be backed
3146 up with a supported media in the system. This should be able to
3147 perform via find commands generating a list of files that are passed
3148 to tar, dd, cpio, cp, gzip, etc., to be directed to the tape machine
3149 or via operations performed on the filesystem itself. Email
3150 notification and GUI status display very important.
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]3151 &lt;/gjob:Details&gt;
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]3152
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]3153 &lt;/gjob:Job&gt;
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]3154
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]3155 &lt;/gjob:Jobs&gt;
3156&lt;/gjob:Helping&gt;</pre>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]3157
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]3158<p>While loading the XML file into an internal DOM tree is a matter of
3159calling only a couple of functions, browsing the tree to gather the ata and
3160generate the internal structures is harder, and more error prone.</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]3161
3162<p>The suggested principle is to be tolerant with respect to the input
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]3163structure. For example, the ordering of the attributes is not significant,
3164the 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]3165depend on the order of the children of a given node, unless it really makes
3166things harder. Here is some code to parse the information for a person:</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]3167<pre>/*
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]3168 * A person record
3169 */
3170typedef struct person {
3171 char *name;
3172 char *email;
3173 char *company;
3174 char *organisation;
3175 char *smail;
3176 char *webPage;
3177 char *phone;
3178} person, *personPtr;
3179
3180/*
3181 * And the code needed to parse it
3182 */
3183personPtr parsePerson(xmlDocPtr doc, xmlNsPtr ns, xmlNodePtr cur) {
3184 personPtr ret = NULL;
3185
3186DEBUG("parsePerson\n");
3187 /*
3188 * allocate the struct
3189 */
3190 ret = (personPtr) malloc(sizeof(person));
3191 if (ret == NULL) {
3192 fprintf(stderr,"out of memory\n");
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]3193 return(NULL);
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]3194 }
3195 memset(ret, 0, sizeof(person));
3196
3197 /* We don't care what the top level element name is */
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]3198 cur = cur-&gt;xmlChildrenNode;
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]3199 while (cur != NULL) {
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]3200 if ((!strcmp(cur-&gt;name, "Person")) &amp;&amp; (cur-&gt;ns == ns))
3201 ret-&gt;name = xmlNodeListGetString(doc, cur-&gt;xmlChildrenNode, 1);
3202 if ((!strcmp(cur-&gt;name, "Email")) &amp;&amp; (cur-&gt;ns == ns))
3203 ret-&gt;email = xmlNodeListGetString(doc, cur-&gt;xmlChildrenNode, 1);
3204 cur = cur-&gt;next;
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]3205 }
3206
3207 return(ret);
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]3208}</pre>
3209
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]3210<p>Here are a couple of things to notice:</p>
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]3211<ul>
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]3212 <li>Usually a recursive parsing style is the more convenient one: XML data
3213 is by nature subject to repetitive constructs and usually exibits highly
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]3214 stuctured patterns.</li>
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]3215 <li>The two arguments of type <em>xmlDocPtr</em> and <em>xmlNsPtr</em>,
3216 i.e. the pointer to the global XML document and the namespace reserved to
3217 the application. Document wide information are needed for example to
3218 decode entities and it's a good coding practice to define a namespace for
3219 your application set of data and test that the element and attributes
3220 you're analyzing actually pertains to your application space. This is
3221 done by a simple equality test (cur-&gt;ns == ns).</li>
Daniel Veillardec70e912001-02-26 20:10:45 +0000[diff] [blame]3222 <li>To retrieve text and attributes value, you can use the function
3223 <em>xmlNodeListGetString</em> to gather all the text and entity reference
3224 nodes generated by the DOM output and produce an single text string.</li>
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]3225</ul>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]3226
3227<p>Here is another piece of code used to parse another level of the
3228structure:</p>
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]3229<pre>#include &lt;libxml/tree.h&gt;
Daniel Veillard361d8452000-04-03 19:48:13 +0000[diff] [blame]3230/*
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]3231 * a Description for a Job
3232 */
3233typedef struct job {
3234 char *projectID;
3235 char *application;
3236 char *category;
3237 personPtr contact;
3238 int nbDevelopers;
3239 personPtr developers[100]; /* using dynamic alloc is left as an exercise */
3240} job, *jobPtr;
3241
3242/*
3243 * And the code needed to parse it
3244 */
3245jobPtr parseJob(xmlDocPtr doc, xmlNsPtr ns, xmlNodePtr cur) {
3246 jobPtr ret = NULL;
3247
3248DEBUG("parseJob\n");
3249 /*
3250 * allocate the struct
3251 */
3252 ret = (jobPtr) malloc(sizeof(job));
3253 if (ret == NULL) {
3254 fprintf(stderr,"out of memory\n");
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]3255 return(NULL);
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]3256 }
3257 memset(ret, 0, sizeof(job));
3258
3259 /* We don't care what the top level element name is */
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]3260 cur = cur-&gt;xmlChildrenNode;
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]3261 while (cur != NULL) {
3262
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]3263 if ((!strcmp(cur-&gt;name, "Project")) &amp;&amp; (cur-&gt;ns == ns)) {
3264 ret-&gt;projectID = xmlGetProp(cur, "ID");
3265 if (ret-&gt;projectID == NULL) {
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]3266 fprintf(stderr, "Project has no ID\n");
3267 }
3268 }
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]3269 if ((!strcmp(cur-&gt;name, "Application")) &amp;&amp; (cur-&gt;ns == ns))
3270 ret-&gt;application = xmlNodeListGetString(doc, cur-&gt;xmlChildrenNode, 1);
3271 if ((!strcmp(cur-&gt;name, "Category")) &amp;&amp; (cur-&gt;ns == ns))
3272 ret-&gt;category = xmlNodeListGetString(doc, cur-&gt;xmlChildrenNode, 1);
3273 if ((!strcmp(cur-&gt;name, "Contact")) &amp;&amp; (cur-&gt;ns == ns))
3274 ret-&gt;contact = parsePerson(doc, ns, cur);
3275 cur = cur-&gt;next;
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]3276 }
3277
3278 return(ret);
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]3279}</pre>
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]3280
Daniel Veillardec70e912001-02-26 20:10:45 +0000[diff] [blame]3281<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]3282boring. Ultimately, it could be possble to write stubbers taking either C
3283data structure definitions, a set of XML examples or an XML DTD and produce
3284the code needed to import and export the content between C data and XML
3285storage. This is left as an exercise to the reader :-)</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]3286
Daniel Veillard6f0adb52000-07-03 11:41:26 +0000[diff] [blame]3287<p>Feel free to use <a href="example/gjobread.c">the code for the full C
3288parsing example</a> as a template, it is also available with Makefile in the
3289Gnome CVS base under gnome-xml/example</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]3290
Daniel Veillardc310d562000-06-23 18:32:15 +0000[diff] [blame]3291<h2><a name="Contributi">Contributions</a></h2>
3292<ul>
Daniel Veillardb8cfbd12001-10-25 10:53:28 +0000[diff] [blame]3293 <li>Bjorn Reese, William Brack and Thomas Broyer have provided a number of
3294 patches, Gary Pennington worked on the validation API, threading support
3295 and Solaris port.</li>
3296 <li>John Fleck helps maintaining the documentation and man pages.</li>
Daniel Veillardc6271d22001-10-27 07:50:58 +0000[diff] [blame]3297 <li><a href="mailto:ari@lusis.org">Ari Johnson</a>
Daniel Veillard51095312001-10-28 18:51:57 +0000[diff] [blame]3298 provides a C++ wrapper for libxml:<br>
Daniel Veillardc6271d22001-10-27 07:50:58 +0000[diff] [blame]3299 Website: <a
3300 href="http://lusis.org/~ari/xml++/">http://lusis.org/~ari/xml++/</a><br>
3301 Download: <a
Daniel Veillard51095312001-10-28 18:51:57 +0000[diff] [blame]3302 href="http://lusis.org/~ari/xml++/libxml++.tar.gz">http://lusis.org/~ari/xml++/libxml++.tar.gz</a></li>
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]3303 <li><a href="mailto:izlatkovic@daenet.de">Igor Zlatkovic</a>
3304 is now the maintainer of the Windows port, <a
Daniel Veillard95189532001-07-26 18:30:26 +0000[diff] [blame]3305 href="http://www.fh-frankfurt.de/~igor/projects/libxml/index.html">he
3306 provides binaries</a></li>
Daniel Veillardc9484202001-10-24 12:35:52 +0000[diff] [blame]3307 <li><a href="mailto:Gary.Pennington@sun.com">Gary Pennington</a>
3308 provides <a href="http://pages.eidosnet.co.uk/~garypen/libxml/">Solaris
Daniel Veillard0a702dc2001-10-19 14:50:57 +0000[diff] [blame]3309 binaries</a></li>
Daniel Veillarde356c282001-03-10 12:32:04 +0000[diff] [blame]3310 <li><a
3311 href="http://mail.gnome.org/archives/xml/2001-March/msg00014.html">Matt
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]3312 Sergeant</a>
3313 developped <a href="http://axkit.org/download/">XML::LibXSLT</a>, a perl
3314 wrapper for libxml2/libxslt as part of the <a
3315 href="http://axkit.com/">AxKit XML application server</a></li>
3316 <li><a href="mailto:fnatter@gmx.net">Felix Natter</a>
3317 and <a href="mailto:geertk@ai.rug.nl">Geert Kloosterman</a> provide <a
Daniel Veillardca989762001-06-23 17:39:29 +0000[diff] [blame]3318 href="libxml-doc.el">an emacs module</a> to lookup libxml(2) functions
Daniel Veillard3f6f7f62000-06-30 17:58:25 +0000[diff] [blame]3319 documentation</li>
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]3320 <li><a href="mailto:sherwin@nlm.nih.gov">Ziying Sherwin</a>
3321 provided <a href="http://xmlsoft.org/messages/0488.html">man
3322 pages</a></li>
Daniel Veillard5168dbf2001-07-07 00:18:23 +0000[diff] [blame]3323 <li>there is a module for <a
3324 href="http://acs-misc.sourceforge.net/nsxml.html">libxml/libxslt support
3325 in OpenNSD/AOLServer</a></li>
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]3326 <li><a href="mailto:dkuhlman@cutter.rexx.com">Dave Kuhlman</a>
3327 provides libxml/libxslt <a href="http://www.rexx.com/~dkuhlman">wrappers
3328 for Python</a></li>
Daniel Veillardc310d562000-06-23 18:32:15 +0000[diff] [blame]3329</ul>
3330
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]3331<p></p>
Daniel Veillardccb09631998-10-27 06:21:04 +0000[diff] [blame]3332</body>
3333</html>