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blob: 4265fe3cdb22fe26582c932b678b9acd494fb9d5 [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 Veillard43d3f612001-11-10 11:57:23 +0000[diff] [blame^]562<h3>2.4.10: Nov 10 2001</h3>
563<ul>
564 <li>URI escaping fix (Joel Young)</li>
565 <li>added xmlGetNodePath() (for paths or XPointers generation)</li>
566 <li>Fixes namespace handling problems when using DTD and validation</li>
567 <li>improvements on xmllint: Morus Walter patches for --format and
568 --encode, Stefan Kost and Heiko Rupp improvements on the --shell</li>
569 <li>fixes for xmlcatalog linking pointed by Weiqi Gao</li>
570 <li>fixes to the HTML parser</li>
571</ul>
572
573<h3>2.4.9: Nov 6 2001</h3>
574<ul>
575 <li>fixes more catalog bugs</li>
576 <li>avoid a compilation problem, improve xmlGetLineNo()</li>
577</ul>
578
Daniel Veillarded421aa2001-11-04 21:22:45 +0000[diff] [blame]579<h3>2.4.8: Nov 4 2001</h3>
580<ul>
581 <li>fixed SGML catalogs broken in previous release, updated xmlcatalog
582 tool</li>
583 <li>fixed a compile errors and some includes troubles.</li>
584</ul>
585
Daniel Veillard52dcab32001-10-30 12:51:17 +0000[diff] [blame]586<h3>2.4.7: Oct 30 2001</h3>
587<ul>
588 <li>exported some debugging interfaces</li>
589 <li>serious rewrite of the catalog code</li>
590 <li>integrated Gary Pennington thread safety patch, added configure option
591 and regression tests</li>
592 <li>removed an HTML parser bug</li>
593 <li>fixed a couple of potentially serious validation bugs</li>
594 <li>integrated the SGML DocBook support in xmllint</li>
595 <li>changed the nanoftp anonymous login passwd</li>
596 <li>some I/O cleanup and a couple of interfaces for Perl wrapper</li>
597 <li>general bug fixes</li>
598 <li>updated xmllint man page by John Fleck</li>
599 <li>some VMS and Windows updates</li>
600</ul>
601
Daniel Veillard60087f32001-10-10 09:45:09 +0000[diff] [blame]602<h3>2.4.6: Oct 10 2001</h3>
603<ul>
Daniel Veillard52dcab32001-10-30 12:51:17 +0000[diff] [blame]604 <li>added an updated man pages by John Fleck</li>
Daniel Veillard60087f32001-10-10 09:45:09 +0000[diff] [blame]605 <li>portability and configure fixes</li>
606 <li>an infinite loop on the HTML parser was removed (William)</li>
607 <li>Windows makefile patches from Igor</li>
608 <li>fixed half a dozen bugs reported fof libxml or libxslt</li>
609 <li>updated xmlcatalog to be able to modify SGML super catalogs</li>
610</ul>
611
Daniel Veillarddadd0872001-09-15 09:21:44 +0000[diff] [blame]612<h3>2.4.5: Sep 14 2001</h3>
613<ul>
614 <li>Remove a few annoying bugs in 2.4.4</li>
615 <li>forces the HTML serializer to output decimal charrefs since some
616 version of Netscape can't handle hexadecimal ones</li>
617</ul>
618
619<h3>1.8.16: Sep 14 2001</h3>
620<ul>
621 <li>maintenance release of the old libxml1 branch, couple of bug and
622 portability fixes</li>
623</ul>
624
Daniel Veillard04382ae2001-09-12 18:51:30 +0000[diff] [blame]625<h3>2.4.4: Sep 12 2001</h3>
626<ul>
627 <li>added --convert to xmlcatalog, bug fixes and cleanups of XML
628 Catalog</li>
629 <li>a few bug fixes and some portability changes</li>
630 <li>some documentation cleanups</li>
631</ul>
632
Daniel Veillard39936902001-08-24 00:49:01 +0000[diff] [blame]633<h3>2.4.3: Aug 23 2001</h3>
634<ul>
635 <li>XML Catalog support see the doc</li>
636 <li>New NaN/Infinity floating point code</li>
637 <li>A few bug fixes</li>
638</ul>
639
640<h3>2.4.2: Aug 15 2001</h3>
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]641<ul>
642 <li>adds xmlLineNumbersDefault() to control line number generation</li>
643 <li>lot of bug fixes</li>
644 <li>the Microsoft MSC projects files shuld now be up to date</li>
645 <li>inheritance of namespaces from DTD defaulted attributes</li>
646 <li>fixes a serious potential security bug</li>
647 <li>added a --format option to xmllint</li>
648</ul>
649
650<h3>2.4.1: July 24 2001</h3>
651<ul>
652 <li>possibility to keep line numbers in the tree</li>
653 <li>some computation NaN fixes</li>
654 <li>extension of the XPath API</li>
655 <li>cleanup for alpha and ia64 targets</li>
656 <li>patch to allow saving through HTTP PUT or POST</li>
Daniel Veillard09ab7e12001-07-10 15:49:44 +0000[diff] [blame]657</ul>
658
659<h3>2.4.0: July 10 2001</h3>
660<ul>
661 <li>Fixed a few bugs in XPath, validation, and tree handling.</li>
662 <li>Fixed XML Base implementation, added a coupel of examples to the
663 regression tests</li>
664 <li>A bit of cleanup</li>
Daniel Veillardab8500d2000-10-15 21:06:19 +0000[diff] [blame]665</ul>
666
Daniel Veillard5b43fde2001-07-05 23:31:40 +0000[diff] [blame]667<h3>2.3.14: July 5 2001</h3>
668<ul>
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]669 <li>fixed some entities problems and reduce mem requirement when
670 substituing them</li>
Daniel Veillard5b43fde2001-07-05 23:31:40 +0000[diff] [blame]671 <li>lots of improvements in the XPath queries interpreter can be
672 substancially faster</li>
673 <li>Makefiles and configure cleanups</li>
674 <li>Fixes to XPath variable eval, and compare on empty node set</li>
675 <li>HTML tag closing bug fixed</li>
676 <li>Fixed an URI reference computating problem when validating</li>
677</ul>
678
Daniel Veillard2adbb512001-06-28 16:20:36 +0000[diff] [blame]679<h3>2.3.13: June 28 2001</h3>
680<ul>
681 <li>2.3.12 configure.in was broken as well as the push mode XML parser</li>
682 <li>a few more fixes for compilation on Windows MSC by Yon Derek</li>
683</ul>
684
685<h3>1.8.14: June 28 2001</h3>
686<ul>
687 <li>Zbigniew Chyla gave a patch to use the old XML parser in push mode</li>
688 <li>Small Makefile fix</li>
689</ul>
690
Daniel Veillard11648102001-06-26 16:08:24 +0000[diff] [blame]691<h3>2.3.12: June 26 2001</h3>
692<ul>
693 <li>lots of cleanup</li>
694 <li>a couple of validation fix</li>
695 <li>fixed line number counting</li>
696 <li>fixed serious problems in the XInclude processing</li>
697 <li>added support for UTF8 BOM at beginning of entities</li>
698 <li>fixed a strange gcc optimizer bugs in xpath handling of float, gcc-3.0
699 miscompile uri.c (William), Thomas Leitner provided a fix for the
700 optimizer on Tru64</li>
701 <li>incorporated Yon Derek and Igor Zlatkovic fixes and improvements for
702 compilation on Windows MSC</li>
703 <li>update of libxml-doc.el (Felix Natter)</li>
704 <li>fixed 2 bugs in URI normalization code</li>
705</ul>
706
Daniel Veillarde3c81b52001-06-17 14:50:34 +0000[diff] [blame]707<h3>2.3.11: June 17 2001</h3>
708<ul>
709 <li>updates to trio, Makefiles and configure should fix some portability
710 problems (alpha)</li>
711 <li>fixed some HTML serialization problems (pre, script, and block/inline
712 handling), added encoding aware APIs, cleanup of this code</li>
713 <li>added xmlHasNsProp()</li>
714 <li>implemented a specific PI for encoding support in the DocBook SGML
715 parser</li>
716 <li>some XPath fixes (-Infinity, / as a function parameter and namespaces
717 node selection)</li>
718 <li>fixed a performance problem and an error in the validation code</li>
719 <li>fixed XInclude routine to implement the recursive behaviour</li>
720 <li>fixed xmlFreeNode problem when libxml is included statically twice</li>
721 <li>added --version to xmllint for bug reports</li>
722</ul>
723
Daniel Veillard2e4f1882001-06-01 10:11:57 +0000[diff] [blame]724<h3>2.3.10: June 1 2001</h3>
725<ul>
726 <li>fixed the SGML catalog support</li>
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]727 <li>a number of reported bugs got fixed, in XPath, iconv detection,
728 XInclude processing</li>
Daniel Veillard2e4f1882001-06-01 10:11:57 +0000[diff] [blame]729 <li>XPath string function should now handle unicode correctly</li>
730</ul>
731
Daniel Veillard4623acd2001-05-19 15:13:15 +0000[diff] [blame]732<h3>2.3.9: May 19 2001</h3>
733
734<p>Lots of bugfixes, and added a basic SGML catalog support:</p>
735<ul>
736 <li>HTML push bugfix #54891 and another patch from Jonas Borgström</li>
737 <li>some serious speed optimisation again</li>
738 <li>some documentation cleanups</li>
739 <li>trying to get better linking on solaris (-R)</li>
740 <li>XPath API cleanup from Thomas Broyer</li>
741 <li>Validation bug fixed #54631, added a patch from Gary Pennington, fixed
742 xmlValidGetValidElements()</li>
743 <li>Added an INSTALL file</li>
744 <li>Attribute removal added to API: #54433</li>
745 <li>added a basic support for SGML catalogs</li>
746 <li>fixed xmlKeepBlanksDefault(0) API</li>
747 <li>bugfix in xmlNodeGetLang()</li>
748 <li>fixed a small configure portability problem</li>
749 <li>fixed an inversion of SYSTEM and PUBLIC identifier in HTML document</li>
750</ul>
751
Daniel Veillarda265af72001-05-14 11:13:58 +0000[diff] [blame]752<h3>1.8.13: May 14 2001</h3>
753<ul>
754 <li>bugfixes release of the old libxml1 branch used by Gnome</li>
755</ul>
756
Daniel Veillard3bbbe6f2001-05-03 11:15:37 +0000[diff] [blame]757<h3>2.3.8: May 3 2001</h3>
758<ul>
759 <li>Integrated an SGML DocBook parser for the Gnome project</li>
760 <li>Fixed a few things in the HTML parser</li>
761 <li>Fixed some XPath bugs raised by XSLT use, tried to fix the floating
762 point portability issue</li>
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]763 <li>Speed improvement (8M/s for SAX, 3M/s for DOM, 1.5M/s for
764 DOM+validation using the XML REC as input and a 700MHz celeron).</li>
Daniel Veillard3bbbe6f2001-05-03 11:15:37 +0000[diff] [blame]765 <li>incorporated more Windows cleanup</li>
766 <li>added xmlSaveFormatFile()</li>
767 <li>fixed problems in copying nodes with entities references (gdome)</li>
768 <li>removed some troubles surrounding the new validation module</li>
769</ul>
770
Daniel Veillarda41123c2001-04-22 19:31:20 +0000[diff] [blame]771<h3>2.3.7: April 22 2001</h3>
772<ul>
773 <li>lots of small bug fixes, corrected XPointer</li>
774 <li>Non determinist content model validation support</li>
775 <li>added xmlDocCopyNode for gdome2</li>
776 <li>revamped the way the HTML parser handles end of tags</li>
777 <li>XPath: corrctions of namespacessupport and number formatting</li>
778 <li>Windows: Igor Zlatkovic patches for MSC compilation</li>
779 <li>HTML ouput fixes from P C Chow and William M. Brack</li>
780 <li>Improved validation speed sensible for DocBook</li>
781 <li>fixed a big bug with ID declared in external parsed entities</li>
782 <li>portability fixes, update of Trio from Bjorn Reese</li>
783</ul>
784
Daniel Veillardafc73112001-04-11 11:51:41 +0000[diff] [blame]785<h3>2.3.6: April 8 2001</h3>
786<ul>
787 <li>Code cleanup using extreme gcc compiler warning options, found and
788 cleared half a dozen potential problem</li>
789 <li>the Eazel team found an XML parser bug</li>
790 <li>cleaned up the user of some of the string formatting function. used the
791 trio library code to provide the one needed when the platform is missing
792 them</li>
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]793 <li>xpath: removed a memory leak and fixed the predicate evaluation
794 problem, extended the testsuite and cleaned up the result. XPointer seems
795 broken ...</li>
Daniel Veillardafc73112001-04-11 11:51:41 +0000[diff] [blame]796</ul>
797
Daniel Veillard56a4cb82001-03-24 17:00:36 +0000[diff] [blame]798<h3>2.3.5: Mar 23 2001</h3>
799<ul>
800 <li>Biggest change is separate parsing and evaluation of XPath expressions,
801 there is some new APIs for this too</li>
802 <li>included a number of bug fixes(XML push parser, 51876, notations,
803 52299)</li>
804 <li>Fixed some portability issues</li>
805</ul>
806
Daniel Veillarde356c282001-03-10 12:32:04 +0000[diff] [blame]807<h3>2.3.4: Mar 10 2001</h3>
808<ul>
809 <li>Fixed bugs #51860 and #51861</li>
810 <li>Added a global variable xmlDefaultBufferSize to allow default buffer
811 size to be application tunable.</li>
812 <li>Some cleanup in the validation code, still a bug left and this part
813 should probably be rewritten to support ambiguous content model :-\</li>
814 <li>Fix a couple of serious bugs introduced or raised by changes in 2.3.3
815 parser</li>
816 <li>Fixed another bug in xmlNodeGetContent()</li>
817 <li>Bjorn fixed XPath node collection and Number formatting</li>
818 <li>Fixed a loop reported in the HTML parsing</li>
819 <li>blank space are reported even if the Dtd content model proves that they
820 are formatting spaces, this is for XmL conformance</li>
821</ul>
822
Daniel Veillardb402c072001-03-01 17:28:58 +0000[diff] [blame]823<h3>2.3.3: Mar 1 2001</h3>
824<ul>
825 <li>small change in XPath for XSLT</li>
826 <li>documentation cleanups</li>
827 <li>fix in validation by Gary Pennington</li>
828 <li>serious parsing performances improvements</li>
829</ul>
830
Daniel Veillardec70e912001-02-26 20:10:45 +0000[diff] [blame]831<h3>2.3.2: Feb 24 2001</h3>
Daniel Veillard71681102001-02-24 17:48:53 +0000[diff] [blame]832<ul>
833 <li>chasing XPath bugs, found a bunch, completed some TODO</li>
834 <li>fixed a Dtd parsing bug</li>
835 <li>fixed a bug in xmlNodeGetContent</li>
836 <li>ID/IDREF support partly rewritten by Gary Pennington</li>
837</ul>
838
Daniel Veillardec70e912001-02-26 20:10:45 +0000[diff] [blame]839<h3>2.3.1: Feb 15 2001</h3>
Daniel Veillard6e6a6cc2001-02-15 15:55:44 +0000[diff] [blame]840<ul>
841 <li>some XPath and HTML bug fixes for XSLT</li>
842 <li>small extension of the hash table interfaces for DOM gdome2
843 implementation</li>
844 <li>A few bug fixes</li>
845</ul>
846
Daniel Veillardec70e912001-02-26 20:10:45 +0000[diff] [blame]847<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]848<ul>
849 <li>Lots of XPath bug fixes</li>
850 <li>Add a mode with Dtd lookup but without validation error reporting for
851 XSLT</li>
852 <li>Add support for text node without escaping (XSLT)</li>
853 <li>bug fixes for xmlCheckFilename</li>
854 <li>validation code bug fixes from Gary Pennington</li>
855 <li>Patch from Paul D. Smith correcting URI path normalization</li>
856 <li>Patch to allow simultaneous install of libxml-devel and
857 libxml2-devel</li>
858 <li>the example Makefile is now fixed</li>
859 <li>added HTML to the RPM packages</li>
860 <li>tree copying bugfixes</li>
861 <li>updates to Windows makefiles</li>
862 <li>optimisation patch from Bjorn Reese</li>
863</ul>
864
Daniel Veillardec70e912001-02-26 20:10:45 +0000[diff] [blame]865<h3>2.2.11: Jan 4 2001</h3>
Daniel Veillard503b8932001-01-05 06:36:31 +0000[diff] [blame]866<ul>
867 <li>bunch of bug fixes (memory I/O, xpath, ftp/http, ...)</li>
868 <li>added htmlHandleOmittedElem()</li>
869 <li>Applied Bjorn Reese's IPV6 first patch</li>
870 <li>Applied Paul D. Smith patches for validation of XInclude results</li>
Daniel Veillard82687162001-01-22 15:32:01 +0000[diff] [blame]871 <li>added XPointer xmlns() new scheme support</li>
Daniel Veillard503b8932001-01-05 06:36:31 +0000[diff] [blame]872</ul>
873
Daniel Veillard2ddd23d2000-11-25 10:42:19 +0000[diff] [blame]874<h3>2.2.10: Nov 25 2000</h3>
Daniel Veillard9d343c42000-11-25 10:12:43 +0000[diff] [blame]875<ul>
876 <li>Fix the Windows problems of 2.2.8</li>
877 <li>integrate OpenVMS patches</li>
878 <li>better handling of some nasty HTML input</li>
879 <li>Improved the XPointer implementation</li>
880 <li>integrate a number of provided patches</li>
881</ul>
882
Daniel Veillard2ddd23d2000-11-25 10:42:19 +0000[diff] [blame]883<h3>2.2.9: Nov 25 2000</h3>
884<ul>
885 <li>erroneous release :-(</li>
886</ul>
887
Daniel Veillard28929b22000-11-13 18:22:49 +0000[diff] [blame]888<h3>2.2.8: Nov 13 2000</h3>
889<ul>
890 <li>First version of <a href="http://www.w3.org/TR/xinclude">XInclude</a>
891 support</li>
892 <li>Patch in conditional section handling</li>
893 <li>updated MS compiler project</li>
894 <li>fixed some XPath problems</li>
895 <li>added an URI escaping function</li>
896 <li>some other bug fixes</li>
897</ul>
898
899<h3>2.2.7: Oct 31 2000</h3>
900<ul>
901 <li>added message redirection</li>
902 <li>XPath improvements (thanks TOM !)</li>
903 <li>xmlIOParseDTD() added</li>
904 <li>various small fixes in the HTML, URI, HTTP and XPointer support</li>
905 <li>some cleanup of the Makefile, autoconf and the distribution content</li>
906</ul>
907
Daniel Veillard29a11cc2000-10-25 13:32:39 +0000[diff] [blame]908<h3>2.2.6: Oct 25 2000:</h3>
909<ul>
910 <li>Added an hash table module, migrated a number of internal structure to
911 those</li>
912 <li>Fixed a posteriori validation problems</li>
913 <li>HTTP module cleanups</li>
914 <li>HTML parser improvements (tag errors, script/style handling, attribute
915 normalization)</li>
916 <li>coalescing of adjacent text nodes</li>
917 <li>couple of XPath bug fixes, exported the internal API</li>
918</ul>
919
Daniel Veillardab8500d2000-10-15 21:06:19 +0000[diff] [blame]920<h3>2.2.5: Oct 15 2000:</h3>
Daniel Veillard4c3a2031999-11-19 17:46:26 +0000[diff] [blame]921<ul>
Daniel Veillard189446d2000-10-13 10:23:06 +0000[diff] [blame]922 <li>XPointer implementation and testsuite</li>
923 <li>Lot of XPath fixes, added variable and functions registration, more
924 tests</li>
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]925 <li>Portability fixes, lots of enhancements toward an easy Windows build
926 and release</li>
Daniel Veillard189446d2000-10-13 10:23:06 +0000[diff] [blame]927 <li>Late validation fixes</li>
928 <li>Integrated a lot of contributed patches</li>
929 <li>added memory management docs</li>
Daniel Veillardab8500d2000-10-15 21:06:19 +0000[diff] [blame]930 <li>a performance problem when using large buffer seems fixed</li>
Daniel Veillard189446d2000-10-13 10:23:06 +0000[diff] [blame]931</ul>
932
933<h3>2.2.4: Oct 1 2000:</h3>
934<ul>
935 <li>main XPath problem fixed</li>
936 <li>Integrated portability patches for Windows</li>
937 <li>Serious bug fixes on the URI and HTML code</li>
Daniel Veillard361d8452000-04-03 19:48:13 +0000[diff] [blame]938</ul>
939
Daniel Veillardd5f97f82000-09-17 16:38:14 +0000[diff] [blame]940<h3>2.2.3: Sep 17 2000</h3>
941<ul>
942 <li>bug fixes</li>
943 <li>cleanup of entity handling code</li>
944 <li>overall review of all loops in the parsers, all sprintf usage has been
945 checked too</li>
946 <li>Far better handling of larges Dtd. Validating against Docbook XML Dtd
947 works smoothly now.</li>
948</ul>
949
950<h3>1.8.10: Sep 6 2000</h3>
951<ul>
952 <li>bug fix release for some Gnome projects</li>
953</ul>
954
955<h3>2.2.2: August 12 2000</h3>
Daniel Veillard786d7c82000-08-12 23:38:57 +0000[diff] [blame]956<ul>
957 <li>mostly bug fixes</li>
Daniel Veillardec78c0f2000-08-25 10:25:23 +0000[diff] [blame]958 <li>started adding routines to access xml parser context options</li>
Daniel Veillard786d7c82000-08-12 23:38:57 +0000[diff] [blame]959</ul>
960
Daniel Veillardd5f97f82000-09-17 16:38:14 +0000[diff] [blame]961<h3>2.2.1: July 21 2000</h3>
Daniel Veillarda2679fa2000-07-22 02:38:15 +0000[diff] [blame]962<ul>
963 <li>a purely bug fixes release</li>
964 <li>fixed an encoding support problem when parsing from a memory block</li>
965 <li>fixed a DOCTYPE parsing problem</li>
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]966 <li>removed a bug in the function allowing to override the memory
967 allocation routines</li>
Daniel Veillarda2679fa2000-07-22 02:38:15 +0000[diff] [blame]968</ul>
969
Daniel Veillardd5f97f82000-09-17 16:38:14 +0000[diff] [blame]970<h3>2.2.0: July 14 2000</h3>
Daniel Veillard94e90602000-07-17 14:38:19 +0000[diff] [blame]971<ul>
972 <li>applied a lot of portability fixes</li>
973 <li>better encoding support/cleanup and saving (content is now always
974 encoded in UTF-8)</li>
975 <li>the HTML parser now correctly handles encodings</li>
976 <li>added xmlHasProp()</li>
977 <li>fixed a serious problem with &amp;#38;</li>
978 <li>propagated the fix to FTP client</li>
979 <li>cleanup, bugfixes, etc ...</li>
980 <li>Added a page about <a href="encoding.html">libxml Internationalization
981 support</a></li>
982</ul>
983
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]984<h3>1.8.9: July 9 2000</h3>
985<ul>
986 <li>fixed the spec the RPMs should be better</li>
987 <li>fixed a serious bug in the FTP implementation, released 1.8.9 to solve
988 rpmfind users problem</li>
989</ul>
990
Daniel Veillard6388e172000-07-03 16:07:19 +0000[diff] [blame]991<h3>2.1.1: July 1 2000</h3>
992<ul>
993 <li>fixes a couple of bugs in the 2.1.0 packaging</li>
994 <li>improvements on the HTML parser</li>
995</ul>
996
Daniel Veillard3f6f7f62000-06-30 17:58:25 +0000[diff] [blame]997<h3>2.1.0 and 1.8.8: June 29 2000</h3>
998<ul>
999 <li>1.8.8 is mostly a comodity package for upgrading to libxml2 accoding to
1000 <a href="upgrade.html">new instructions</a>. It fixes a nasty problem
1001 about &amp;#38; charref parsing</li>
1002 <li>2.1.0 also ease the upgrade from libxml v1 to the recent version. it
1003 also contains numerous fixes and enhancements:
1004 <ul>
1005 <li>added xmlStopParser() to stop parsing</li>
1006 <li>improved a lot parsing speed when there is large CDATA blocs</li>
1007 <li>includes XPath patches provided by Picdar Technology</li>
1008 <li>tried to fix as much as possible DtD validation and namespace
1009 related problems</li>
1010 <li>output to a given encoding has been added/tested</li>
1011 <li>lot of various fixes</li>
1012 </ul>
1013 </li>
1014</ul>
1015
Daniel Veillarde0aed302000-04-16 08:52:20 +0000[diff] [blame]1016<h3>2.0.0: Apr 12 2000</h3>
Daniel Veillard361d8452000-04-03 19:48:13 +0000[diff] [blame]1017<ul>
1018 <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]1019 idea to check the 1.x to 2.x upgrade instructions. NOTE: while initally
1020 scheduled for Apr 3 the relase occured only on Apr 12 due to massive
1021 workload.</li>
Daniel Veillard361d8452000-04-03 19:48:13 +0000[diff] [blame]1022 <li>The include are now located under $prefix/include/libxml (instead of
Daniel Veillarde0aed302000-04-16 08:52:20 +0000[diff] [blame]1023 $prefix/include/gnome-xml), they also are referenced by
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]1024 <pre>#include &lt;libxml/xxx.h&gt;</pre>
Daniel Veillarde0aed302000-04-16 08:52:20 +0000[diff] [blame]1025 <p>instead of</p>
Daniel Veillard361d8452000-04-03 19:48:13 +0000[diff] [blame]1026 <pre>#include "xxx.h"</pre>
1027 </li>
Daniel Veillard8f621982000-03-20 13:07:15 +0000[diff] [blame]1028 <li>a new URI module for parsing URIs and following strictly RFC 2396</li>
1029 <li>the memory allocation routines used by libxml can now be overloaded
1030 dynamically by using xmlMemSetup()</li>
Daniel Veillard361d8452000-04-03 19:48:13 +0000[diff] [blame]1031 <li>The previously CVS only tool tester has been renamed
1032 <strong>xmllint</strong> and is now installed as part of the libxml2
1033 package</li>
Daniel Veillarde0aed302000-04-16 08:52:20 +0000[diff] [blame]1034 <li>The I/O interface has been revamped. There is now ways to plug in
1035 specific I/O modules, either at the URI scheme detection level using
1036 xmlRegisterInputCallbacks() or by passing I/O functions when creating a
1037 parser context using xmlCreateIOParserCtxt()</li>
1038 <li>there is a C preprocessor macro LIBXML_VERSION providing the version
1039 number of the libxml module in use</li>
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]1040 <li>a number of optional features of libxml can now be excluded at
1041 configure time (FTP/HTTP/HTML/XPath/Debug)</li>
Daniel Veillardedfb29b2000-03-14 19:59:05 +0000[diff] [blame]1042</ul>
1043
1044<h3>2.0.0beta: Mar 14 2000</h3>
1045<ul>
1046 <li>This is a first Beta release of libxml version 2</li>
Daniel Veillarde356c282001-03-10 12:32:04 +0000[diff] [blame]1047 <li>It's available only from<a href="ftp://xmlsoft.org/">xmlsoft.org
1048 FTP</a>, it's packaged as libxml2-2.0.0beta and available as tar and
1049 RPMs</li>
Daniel Veillardedfb29b2000-03-14 19:59:05 +0000[diff] [blame]1050 <li>This version is now the head in the Gnome CVS base, the old one is
1051 available under the tag LIB_XML_1_X</li>
1052 <li>This includes a very large set of changes. Froma programmatic point of
1053 view applications should not have to be modified too much, check the <a
1054 href="upgrade.html">upgrade page</a></li>
1055 <li>Some interfaces may changes (especially a bit about encoding).</li>
1056 <li>the updates includes:
Daniel Veillard6c8b1172000-03-01 00:40:41 +0000[diff] [blame]1057 <ul>
Daniel Veillardedfb29b2000-03-14 19:59:05 +0000[diff] [blame]1058 <li>fix I18N support. ISO-Latin-x/UTF-8/UTF-16 (nearly) seems correctly
1059 handled now</li>
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]1060 <li>Better handling of entities, especially well formedness checking
1061 and proper PEref extensions in external subsets</li>
Daniel Veillard6c8b1172000-03-01 00:40:41 +0000[diff] [blame]1062 <li>DTD conditional sections</li>
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]1063 <li>Validation now correcly handle entities content</li>
Daniel Veillard6c8b1172000-03-01 00:40:41 +0000[diff] [blame]1064 <li><a href="http://rpmfind.net/tools/gdome/messages/0039.html">change
1065 structures to accomodate DOM</a></li>
Daniel Veillard6c8b1172000-03-01 00:40:41 +0000[diff] [blame]1066 </ul>
1067 </li>
Daniel Veillardedfb29b2000-03-14 19:59:05 +0000[diff] [blame]1068 <li>Serious progress were made toward compliance, <a
1069 href="conf/result.html">here are the result of the test</a> against the
1070 OASIS testsuite (except the japanese tests since I don't support that
1071 encoding yet). This URL is rebuilt every couple of hours using the CVS
1072 head version.</li>
Daniel Veillarde41f2b72000-01-30 20:00:07 +0000[diff] [blame]1073</ul>
1074
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]1075<h3>1.8.7: Mar 6 2000</h3>
1076<ul>
1077 <li>This is a bug fix release:</li>
1078 <li>It is possible to disable the ignorable blanks heuristic used by
1079 libxml-1.x, a new function xmlKeepBlanksDefault(0) will allow this. Note
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]1080 that for adherence to XML spec, this behaviour will be disabled by
1081 default in 2.x . The same function will allow to keep compatibility for
1082 old code.</li>
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]1083 <li>Blanks in &lt;a&gt; &lt;/a&gt; constructs are not ignored anymore,
1084 avoiding heuristic is really the Right Way :-\</li>
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]1085 <li>The unchecked use of snprintf which was breaking libxml-1.8.6
1086 compilation on some platforms has been fixed</li>
1087 <li>nanoftp.c nanohttp.c: Fixed '#' and '?' stripping when processing
1088 URIs</li>
1089</ul>
1090
Daniel Veillarde41f2b72000-01-30 20:00:07 +0000[diff] [blame]1091<h3>1.8.6: Jan 31 2000</h3>
1092<ul>
1093 <li>added a nanoFTP transport module, debugged until the new version of <a
1094 href="http://rpmfind.net/linux/rpm2html/rpmfind.html">rpmfind</a> can use
1095 it without troubles</li>
Daniel Veillardda07c342000-01-25 18:31:22 +0000[diff] [blame]1096</ul>
1097
1098<h3>1.8.5: Jan 21 2000</h3>
1099<ul>
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]1100 <li>adding APIs to parse a well balanced chunk of XML (production <a
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]1101 href="http://www.w3.org/TR/REC-xml#NT-content">[43] content</a> of the
1102 XML spec)</li>
Daniel Veillard461a66c2000-01-18 18:01:01 +0000[diff] [blame]1103 <li>fixed a hideous bug in xmlGetProp pointed by Rune.Djurhuus@fast.no</li>
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]1104 <li>Jody Goldberg &lt;jgoldberg@home.com&gt; provided another patch trying
1105 to solve the zlib checks problems</li>
Daniel Veillard461a66c2000-01-18 18:01:01 +0000[diff] [blame]1106 <li>The current state in gnome CVS base is expected to ship as 1.8.5 with
1107 gnumeric soon</li>
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]1108</ul>
1109
1110<h3>1.8.4: Jan 13 2000</h3>
1111<ul>
1112 <li>bug fixes, reintroduced xmlNewGlobalNs(), fixed xmlNewNs()</li>
1113 <li>all exit() call should have been removed from libxml</li>
1114 <li>fixed a problem with INCLUDE_WINSOCK on WIN32 platform</li>
1115 <li>added newDocFragment()</li>
Daniel Veillardf84f71f2000-01-05 19:54:23 +0000[diff] [blame]1116</ul>
1117
1118<h3>1.8.3: Jan 5 2000</h3>
1119<ul>
1120 <li>a Push interface for the XML and HTML parsers</li>
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]1121 <li>a shell-like interface to the document tree (try tester --shell :-)</li>
Daniel Veillarddbfd6411999-12-28 16:35:14 +0000[diff] [blame]1122 <li>lots of bug fixes and improvement added over XMas hollidays</li>
Daniel Veillard437b87b2000-01-03 17:30:46 +0000[diff] [blame]1123 <li>fixed the DTD parsing code to work with the xhtml DTD</li>
Daniel Veillardf84f71f2000-01-05 19:54:23 +0000[diff] [blame]1124 <li>added xmlRemoveProp(), xmlRemoveID() and xmlRemoveRef()</li>
1125 <li>Fixed bugs in xmlNewNs()</li>
Daniel Veillard437b87b2000-01-03 17:30:46 +0000[diff] [blame]1126 <li>External entity loading code has been revamped, now it uses
Daniel Veillardf84f71f2000-01-05 19:54:23 +0000[diff] [blame]1127 xmlLoadExternalEntity(), some fix on entities processing were added</li>
Daniel Veillard437b87b2000-01-03 17:30:46 +0000[diff] [blame]1128 <li>cleaned up WIN32 includes of socket stuff</li>
Daniel Veillard5cb5ab81999-12-21 15:35:29 +0000[diff] [blame]1129</ul>
1130
1131<h3>1.8.2: Dec 21 1999</h3>
1132<ul>
Daniel Veillardb24054a1999-12-18 15:32:46 +0000[diff] [blame]1133 <li>I got another problem with includes and C++, I hope this issue is fixed
1134 for good this time</li>
Daniel Veillard5cb5ab81999-12-21 15:35:29 +0000[diff] [blame]1135 <li>Added a few tree modification functions: xmlReplaceNode,
1136 xmlAddPrevSibling, xmlAddNextSibling, xmlNodeSetName and
1137 xmlDocSetRootElement</li>
1138 <li>Tried to improve the HTML output with help from <a
1139 href="mailto:clahey@umich.edu">Chris Lahey</a></li>
Daniel Veillarde4e51311999-12-18 15:32:46 +0000[diff] [blame]1140</ul>
Daniel Veillardb24054a1999-12-18 15:32:46 +0000[diff] [blame]1141
Daniel Veillarde4e51311999-12-18 15:32:46 +0000[diff] [blame]1142<h3>1.8.1: Dec 18 1999</h3>
1143<ul>
1144 <li>various patches to avoid troubles when using libxml with C++ compilers
1145 the "namespace" keyword and C escaping in include files</li>
1146 <li>a problem in one of the core macros IS_CHAR was corrected</li>
1147 <li>fixed a bug introduced in 1.8.0 breaking default namespace processing,
1148 and more specifically the Dia application</li>
Daniel Veillard944b5ff1999-12-15 19:08:24 +0000[diff] [blame]1149 <li>fixed a posteriori validation (validation after parsing, or by using a
1150 Dtd not specified in the original document)</li>
Daniel Veillardb24054a1999-12-18 15:32:46 +0000[diff] [blame]1151 <li>fixed a bug in</li>
Daniel Veillard10a2c651999-12-12 13:03:50 +0000[diff] [blame]1152</ul>
1153
1154<h3>1.8.0: Dec 12 1999</h3>
1155<ul>
1156 <li>cleanup, especially memory wise</li>
1157 <li>the parser should be more reliable, especially the HTML one, it should
1158 not crash, whatever the input !</li>
1159 <li>Integrated various patches, especially a speedup improvement for large
1160 dataset from <a href="mailto:cnygard@bellatlantic.net">Carl Nygard</a>,
1161 configure with --with-buffers to enable them.</li>
1162 <li>attribute normalization, oops should have been added long ago !</li>
1163 <li>attributes defaulted from Dtds should be available, xmlSetProp() now
1164 does entities escapting by default.</li>
Daniel Veillard4c3a2031999-11-19 17:46:26 +0000[diff] [blame]1165</ul>
Daniel Veillard35008381999-10-25 13:15:52 +0000[diff] [blame]1166
1167<h3>1.7.4: Oct 25 1999</h3>
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]1168<ul>
Daniel Veillard35008381999-10-25 13:15:52 +0000[diff] [blame]1169 <li>Lots of HTML improvement</li>
1170 <li>Fixed some errors when saving both XML and HTML</li>
1171 <li>More examples, the regression tests should now look clean</li>
1172 <li>Fixed a bug with contiguous charref</li>
1173</ul>
1174
1175<h3>1.7.3: Sep 29 1999</h3>
1176<ul>
1177 <li>portability problems fixed</li>
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]1178 <li>snprintf was used unconditionnally, leading to link problems on system
Daniel Veillard35008381999-10-25 13:15:52 +0000[diff] [blame]1179 were it's not available, fixed</li>
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]1180</ul>
1181
1182<h3>1.7.1: Sep 24 1999</h3>
1183<ul>
1184 <li>The basic type for strings manipulated by libxml has been renamed in
1185 1.7.1 from <strong>CHAR</strong> to <strong>xmlChar</strong>. The reason
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]1186 is that CHAR was conflicting with a predefined type on Windows. However
1187 on non WIN32 environment, compatibility is provided by the way of a
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]1188 <strong>#define </strong>.</li>
1189 <li>Changed another error : the use of a structure field called errno, and
1190 leading to troubles on platforms where it's a macro</li>
1191</ul>
1192
1193<h3>1.7.0: sep 23 1999</h3>
1194<ul>
1195 <li>Added the ability to fetch remote DTD or parsed entities, see the <a
Daniel Veillard9cb5ff42001-01-29 08:22:21 +0000[diff] [blame]1196 href="html/libxml-nanohttp.html">nanohttp</a> module.</li>
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]1197 <li>Added an errno to report errors by another mean than a simple printf
1198 like callback</li>
1199 <li>Finished ID/IDREF support and checking when validation</li>
1200 <li>Serious memory leaks fixed (there is now a <a
Daniel Veillard9cb5ff42001-01-29 08:22:21 +0000[diff] [blame]1201 href="html/libxml-xmlmemory.html">memory wrapper</a> module)</li>
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]1202 <li>Improvement of <a href="http://www.w3.org/TR/xpath">XPath</a>
1203 implementation</li>
1204 <li>Added an HTML parser front-end</li>
1205</ul>
1206
1207<h2><a name="XML">XML</a></h2>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]1208
Daniel Veillard402e8c82000-02-29 22:57:47 +0000[diff] [blame]1209<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]1210markup-based structured documents. Here is <a name="example">an example XML
1211document</a>:</p>
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]1212<pre>&lt;?xml version="1.0"?&gt;
1213&lt;EXAMPLE prop1="gnome is great" prop2="&amp;amp; linux too"&gt;
1214 &lt;head&gt;
1215 &lt;title&gt;Welcome to Gnome&lt;/title&gt;
1216 &lt;/head&gt;
1217 &lt;chapter&gt;
1218 &lt;title&gt;The Linux adventure&lt;/title&gt;
1219 &lt;p&gt;bla bla bla ...&lt;/p&gt;
1220 &lt;image href="linus.gif"/&gt;
1221 &lt;p&gt;...&lt;/p&gt;
1222 &lt;/chapter&gt;
1223&lt;/EXAMPLE&gt;</pre>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]1224
Daniel Veillard402e8c82000-02-29 22:57:47 +0000[diff] [blame]1225<p>The first line specifies that it's an XML document and gives useful
1226information about its encoding. Then the document is a text format whose
1227structure is specified by tags between brackets. <strong>Each tag opened has
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]1228to be closed</strong>. XML is pedantic about this. However, if a tag is empty
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]1229(no content), a single tag can serve as both the opening and closing tag if
1230it ends with <code>/&gt;</code> rather than with <code>&gt;</code>. Note
1231that, for example, the image tag has no content (just an attribute) and is
1232closed by ending the tag with <code>/&gt;</code>.</p>
Daniel Veillardccb09631998-10-27 06:21:04 +0000[diff] [blame]1233
Daniel Veillard402e8c82000-02-29 22:57:47 +0000[diff] [blame]1234<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]1235structured document maintenance (where it follows the steps of SGML) to
1236simple data encoding mechanisms like configuration file formatting (glade),
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]1237spreadsheets (gnumeric), or even shorter lived documents such as WebDAV where
1238it is used to encode remote calls between a client and a server.</p>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]1239
Daniel Veillard82687162001-01-22 15:32:01 +0000[diff] [blame]1240<h2><a name="XSLT">XSLT</a></h2>
1241
Daniel Veillard6e6a6cc2001-02-15 15:55:44 +0000[diff] [blame]1242<p>Check <a href="http://xmlsoft.org/XSLT">the separate libxslt page</a></p>
1243
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]1244<p><a href="http://www.w3.org/TR/xslt">XSL Transformations</a>, is a
1245language for transforming XML documents into other XML documents (or
1246HTML/textual output).</p>
Daniel Veillard82687162001-01-22 15:32:01 +0000[diff] [blame]1247
1248<p>A separate library called libxslt is being built on top of libxml2. This
1249module "libxslt" can be found in the Gnome CVS base too.</p>
1250
Daniel Veillard383b1472001-01-23 11:39:52 +0000[diff] [blame]1251<p>You can check the <a
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]1252href="http://cvs.gnome.org/lxr/source/libxslt/FEATURES">features</a>
1253supported and the progresses on the <a
Daniel Veillard82687162001-01-22 15:32:01 +0000[diff] [blame]1254href="http://cvs.gnome.org/lxr/source/libxslt/ChangeLog">Changelog</a></p>
1255
Daniel Veillardb8cfbd12001-10-25 10:53:28 +0000[diff] [blame]1256<h2><a name="architecture">libxml architecture</a></h2>
Daniel Veillard4540be42000-08-19 16:40:28 +0000[diff] [blame]1257
Daniel Veillardec70e912001-02-26 20:10:45 +0000[diff] [blame]1258<p>Libxml is made of multiple components; some of them are optional, and most
1259of the block interfaces are public. The main components are:</p>
Daniel Veillard4540be42000-08-19 16:40:28 +0000[diff] [blame]1260<ul>
1261 <li>an Input/Output layer</li>
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]1262 <li>FTP and HTTP client layers (optional)</li>
Daniel Veillard4540be42000-08-19 16:40:28 +0000[diff] [blame]1263 <li>an Internationalization layer managing the encodings support</li>
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]1264 <li>a URI module</li>
Daniel Veillard4540be42000-08-19 16:40:28 +0000[diff] [blame]1265 <li>the XML parser and its basic SAX interface</li>
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]1266 <li>an HTML parser using the same SAX interface (optional)</li>
Daniel Veillard4540be42000-08-19 16:40:28 +0000[diff] [blame]1267 <li>a SAX tree module to build an in-memory DOM representation</li>
1268 <li>a tree module to manipulate the DOM representation</li>
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]1269 <li>a validation module using the DOM representation (optional)</li>
Daniel Veillard4540be42000-08-19 16:40:28 +0000[diff] [blame]1270 <li>an XPath module for global lookup in a DOM representation
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]1271 (optional)</li>
1272 <li>a debug module (optional)</li>
Daniel Veillard4540be42000-08-19 16:40:28 +0000[diff] [blame]1273</ul>
1274
1275<p>Graphically this gives the following:</p>
1276
1277<p><img src="libxml.gif" alt="a graphical view of the various"></p>
1278
1279<p></p>
1280
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]1281<h2><a name="tree">The tree output</a></h2>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]1282
1283<p>The parser returns a tree built during the document analysis. The value
Daniel Veillard402e8c82000-02-29 22:57:47 +0000[diff] [blame]1284returned is an <strong>xmlDocPtr</strong> (i.e., a pointer to an
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]1285<strong>xmlDoc</strong> structure). This structure contains information such
Daniel Veillard306be992000-07-03 12:38:45 +0000[diff] [blame]1286as the file name, the document type, and a <strong>children</strong> pointer
1287which is the root of the document (or more exactly the first child under the
1288root which is the document). The tree is made of <strong>xmlNode</strong>s,
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]1289chained in double-linked lists of siblings and with a children&lt;-&gt;parent
Daniel Veillard306be992000-07-03 12:38:45 +0000[diff] [blame]1290relationship. An xmlNode can also carry properties (a chain of xmlAttr
1291structures). An attribute may have a value which is a list of TEXT or
1292ENTITY_REF nodes.</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]1293
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]1294<p>Here is an example (erroneous with respect to the XML spec since there
1295should be only one ELEMENT under the root):</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]1296
1297<p><img src="structure.gif" alt=" structure.gif "></p>
1298
1299<p>In the source package there is a small program (not installed by default)
Daniel Veillard361d8452000-04-03 19:48:13 +0000[diff] [blame]1300called <strong>xmllint</strong> which parses XML files given as argument and
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]1301prints them back as parsed. This is useful for detecting errors both in XML
1302code and in the XML parser itself. It has an option <strong>--debug</strong>
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]1303which prints the actual in-memory structure of the document; here is the
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]1304result with the <a href="#example">example</a> given before:</p>
Daniel Veillard10c6a8f1998-10-28 01:00:12 +0000[diff] [blame]1305<pre>DOCUMENT
1306version=1.0
1307standalone=true
1308 ELEMENT EXAMPLE
1309 ATTRIBUTE prop1
1310 TEXT
1311 content=gnome is great
1312 ATTRIBUTE prop2
1313 ENTITY_REF
1314 TEXT
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]1315 content= linux too
Daniel Veillard402e8c82000-02-29 22:57:47 +0000[diff] [blame]1316 ELEMENT head
Daniel Veillard10c6a8f1998-10-28 01:00:12 +0000[diff] [blame]1317 ELEMENT title
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]1318 TEXT
1319 content=Welcome to Gnome
Daniel Veillard10c6a8f1998-10-28 01:00:12 +0000[diff] [blame]1320 ELEMENT chapter
1321 ELEMENT title
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]1322 TEXT
1323 content=The Linux adventure
Daniel Veillard10c6a8f1998-10-28 01:00:12 +0000[diff] [blame]1324 ELEMENT p
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]1325 TEXT
1326 content=bla bla bla ...
Daniel Veillard10c6a8f1998-10-28 01:00:12 +0000[diff] [blame]1327 ELEMENT image
1328 ATTRIBUTE href
1329 TEXT
1330 content=linus.gif
1331 ELEMENT p
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]1332 TEXT
1333 content=...</pre>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]1334
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]1335<p>This should be useful for learning the internal representation model.</p>
Daniel Veillardccb09631998-10-27 06:21:04 +0000[diff] [blame]1336
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]1337<h2><a name="interface">The SAX interface</a></h2>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]1338
Daniel Veillard402e8c82000-02-29 22:57:47 +0000[diff] [blame]1339<p>Sometimes the DOM tree output is just too large to fit reasonably into
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]1340memory. 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]1341loaded using libxml), it's better to use the SAX interface of libxml. SAX is
1342a <strong>callback-based interface</strong> to the parser. Before parsing,
1343the application layer registers a customized set of callbacks which are
1344called by the library as it progresses through the XML input.</p>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]1345
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]1346<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]1347libxml, see the <a
1348href="http://www.daa.com.au/~james/gnome/xml-sax/xml-sax.html">nice
1349documentation</a>.written by <a href="mailto:james@daa.com.au">James
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]1350Henstridge</a>.</p>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]1351
1352<p>You can debug the SAX behaviour by using the <strong>testSAX</strong>
1353program located in the gnome-xml module (it's usually not shipped in the
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]1354binary packages of libxml, but you can find it in the tar source
Daniel Veillard402e8c82000-02-29 22:57:47 +0000[diff] [blame]1355distribution). Here is the sequence of callbacks that would be reported by
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]1356testSAX when parsing the example XML document shown earlier:</p>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]1357<pre>SAX.setDocumentLocator()
1358SAX.startDocument()
1359SAX.getEntity(amp)
1360SAX.startElement(EXAMPLE, prop1='gnome is great', prop2='&amp;amp; linux too')
1361SAX.characters( , 3)
1362SAX.startElement(head)
1363SAX.characters( , 4)
1364SAX.startElement(title)
1365SAX.characters(Welcome to Gnome, 16)
1366SAX.endElement(title)
1367SAX.characters( , 3)
1368SAX.endElement(head)
1369SAX.characters( , 3)
1370SAX.startElement(chapter)
1371SAX.characters( , 4)
1372SAX.startElement(title)
1373SAX.characters(The Linux adventure, 19)
1374SAX.endElement(title)
1375SAX.characters( , 4)
1376SAX.startElement(p)
1377SAX.characters(bla bla bla ..., 15)
1378SAX.endElement(p)
1379SAX.characters( , 4)
1380SAX.startElement(image, href='linus.gif')
1381SAX.endElement(image)
1382SAX.characters( , 4)
1383SAX.startElement(p)
1384SAX.characters(..., 3)
1385SAX.endElement(p)
1386SAX.characters( , 3)
1387SAX.endElement(chapter)
1388SAX.characters( , 1)
1389SAX.endElement(EXAMPLE)
1390SAX.endDocument()</pre>
1391
Daniel Veillardec70e912001-02-26 20:10:45 +0000[diff] [blame]1392<p>Most of the other interfaces of libxml are based on the DOM tree-building
1393facility, so nearly everything up to the end of this document presupposes the
1394use of the standard DOM tree build. Note that the DOM tree itself is built by
1395a set of registered default callbacks, without internal specific
1396interface.</p>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]1397
Daniel Veillardb8cfbd12001-10-25 10:53:28 +0000[diff] [blame]1398<h2><a name="Validation">Validation &amp; DTDs</a></h2>
1399
1400<p>Table of Content:</p>
1401<ol>
1402 <li><a href="#General5">General overview</a></li>
1403 <li><a href="#definition">The definition</a></li>
1404 <li><a href="#Simple">Simple rules</a>
1405 <ol>
Daniel Veillard9c466822001-10-25 12:03:39 +0000[diff] [blame]1406 <li><a href="#reference">How to reference a DTD from a document</a></li>
Daniel Veillardb8cfbd12001-10-25 10:53:28 +0000[diff] [blame]1407 <li><a href="#Declaring">Declaring elements</a></li>
1408 <li><a href="#Declaring1">Declaring attributes</a></li>
1409 </ol>
1410 </li>
1411 <li><a href="#Some">Some examples</a></li>
1412 <li><a href="#validate">How to validate</a></li>
1413 <li><a href="#Other">Other resources</a></li>
1414</ol>
1415
1416<h3><a name="General5">General overview</a></h3>
1417
1418<p>Well what is validation and what is a DTD ?</p>
1419
1420<p>DTD is the acronym for Document Type Definition. This is a description of
1421the content for a familly of XML files. This is part of the XML 1.0
1422specification, and alows to describe and check that a given document instance
1423conforms to a set of rules detailing its structure and content.</p>
1424
1425<p>Validation is the process of checking a document against a DTD (more
1426generally against a set of construction rules).</p>
1427
1428<p>The validation process and building DTDs are the two most difficult parts
1429of the XML life cycle. Briefly a DTD defines all the possibles element to be
1430found within your document, what is the formal shape of your document tree
1431(by defining the allowed content of an element, either text, a regular
1432expression for the allowed list of children, or mixed content i.e. both text
1433and children). The DTD also defines the allowed attributes for all elements
1434and the types of the attributes.</p>
1435
1436<h3><a name="definition1">The definition</a></h3>
1437
1438<p>The <a href="http://www.w3.org/TR/REC-xml">W3C XML Recommendation</a> (<a
1439href="http://www.xml.com/axml/axml.html">Tim Bray's annotated version of
1440Rev1</a>):</p>
1441<ul>
1442 <li><a href="http://www.w3.org/TR/REC-xml#elemdecls">Declaring
1443 elements</a></li>
1444 <li><a href="http://www.w3.org/TR/REC-xml#attdecls">Declaring
1445 attributes</a></li>
1446</ul>
1447
1448<p>(unfortunately) all this is inherited from the SGML world, the syntax is
1449ancient...</p>
1450
1451<h3><a name="Simple1">Simple rules</a></h3>
1452
1453<p>Writing DTD can be done in multiple ways, the rules to build them if you
1454need something fixed or something which can evolve over time can be radically
1455different. Really complex DTD like Docbook ones are flexible but quite harder
1456to design. I will just focuse on DTDs for a formats with a fixed simple
1457structure. It is just a set of basic rules, and definitely not exhaustive nor
1458useable for complex DTD design.</p>
1459
1460<h4><a name="reference1">How to reference a DTD from a document</a>:</h4>
1461
1462<p>Assuming the top element of the document is <code>spec</code> and the dtd
1463is placed in the file <code>mydtd</code> in the subdirectory
1464<code>dtds</code> of the directory from where the document were loaded:</p>
1465
1466<p><code>&lt;!DOCTYPE spec SYSTEM "dtds/mydtd"&gt;</code></p>
1467
1468<p>Notes:</p>
1469<ul>
1470 <li>the system string is actually an URI-Reference (as defined in <a
1471 href="http://www.ietf.org/rfc/rfc2396.txt">RFC 2396</a>) so you can use a
1472 full URL string indicating the location of your DTD on the Web, this is a
1473 really good thing to do if you want others to validate your document</li>
1474 <li>it is also possible to associate a <code>PUBLIC</code> identifier (a
1475 magic string) so that the DTd is looked up in catalogs on the client side
1476 without having to locate it on the web</li>
1477 <li>a dtd contains a set of elements and attributes declarations, but they
1478 don't define what the root of the document should be. This is explicitely
1479 told to the parser/validator as the first element of the
1480 <code>DOCTYPE</code> declaration.</li>
1481</ul>
1482
1483<h4><a name="Declaring2">Declaring elements</a>:</h4>
1484
1485<p>The following declares an element <code>spec</code>:</p>
1486
1487<p><code>&lt;!ELEMENT spec (front, body, back?)&gt;</code></p>
1488
1489<p>it also expresses that the spec element contains one <code>front</code>,
1490one <code>body</code> and one optionnal <code>back</code> children elements
1491in this order. The declaration of one element of the structure and its
1492content are done in a single declaration. Similary the following declares
1493<code>div1</code> elements:</p>
1494
1495<p><code>&lt;!ELEMENT div1 (head, (p | list | note)*, div2*)&gt;</code></p>
1496
1497<p>means div1 contains one <code>head</code> then a series of optional
1498<code>p</code>, <code>list</code>s and <code>note</code>s and then an
1499optional <code>div2</code>. And last but not least an element can contain
1500text:</p>
1501
1502<p><code>&lt;!ELEMENT b (#PCDATA)&gt;</code></p>
1503
1504<p><code>b</code> contains text or being of mixed content (text and elements
1505in no particular order):</p>
1506
1507<p><code>&lt;!ELEMENT p (#PCDATA|a|ul|b|i|em)*&gt;</code></p>
1508
1509<p><code>p </code>can contain text or <code>a</code>, <code>ul</code>,
1510<code>b</code>, <code>i </code>or <code>em</code> elements in no particular
1511order.</p>
1512
1513<h4><a name="Declaring1">Declaring attributes</a>:</h4>
1514
1515<p>again the attributes declaration includes their content definition:</p>
1516
1517<p><code>&lt;!ATTLIST termdef name CDATA #IMPLIED&gt;</code></p>
1518
1519<p>means that the element <code>termdef</code> can have a <code>name</code>
1520attribute containing text (<code>CDATA</code>) and which is optionnal
1521(<code>#IMPLIED</code>). The attribute value can also be defined within a
1522set:</p>
1523
1524<p><code>&lt;!ATTLIST list type (bullets|ordered|glossary)
1525"ordered"&gt;</code></p>
1526
1527<p>means <code>list</code> element have a <code>type</code> attribute with 3
1528allowed values "bullets", "ordered" or "glossary" and which default to
1529"ordered" if the attribute is not explicitely specified.</p>
1530
1531<p>The content type of an attribute can be text (<code>CDATA</code>),
1532anchor/reference/references
1533(<code>ID</code>/<code>IDREF</code>/<code>IDREFS</code>), entity(ies)
1534(<code>ENTITY</code>/<code>ENTITIES</code>) or name(s)
1535(<code>NMTOKEN</code>/<code>NMTOKENS</code>). The following defines that a
1536<code>chapter</code> element can have an optional <code>id</code> attribute
1537of type <code>ID</code>, usable for reference from attribute of type
1538IDREF:</p>
1539
1540<p><code>&lt;!ATTLIST chapter id ID #IMPLIED&gt;</code></p>
1541
1542<p>The last value of an attribute definition can be <code>#REQUIRED
1543</code>meaning that the attribute has to be given, <code>#IMPLIED</code>
1544meaning that it is optional, or the default value (possibly prefixed by
1545<code>#FIXED</code> if it is the only allowed).</p>
1546
1547<p>Notes:</p>
1548<ul>
1549 <li>usually the attributes pertaining to a given element are declared in a
1550 single expression, but it is just a convention adopted by a lot of DTD
1551 writers:
1552 <pre>&lt;!ATTLIST termdef
1553 id ID #REQUIRED
1554 name CDATA #IMPLIED&gt;</pre>
1555 <p>The previous construct defines both <code>id</code> and
1556 <code>name</code> attributes for the element <code>termdef</code></p>
1557 </li>
1558</ul>
1559
1560<h3><a name="Some1">Some examples</a></h3>
1561
1562<p>The directory <code>test/valid/dtds/</code> in the libxml distribution
1563contains some complex DTD examples. The <code>test/valid/dia.xml</code>
1564example shows an XML file where the simple DTD is directly included within
1565the document.</p>
1566
1567<h3><a name="validate1">How to validate</a></h3>
1568
1569<p>The simplest is to use the xmllint program comming with libxml. The
1570<code>--valid</code> option turn on validation of the files given as input,
1571for example the following validates a copy of the first revision of the XML
15721.0 specification:</p>
1573
1574<p><code>xmllint --valid --noout test/valid/REC-xml-19980210.xml</code></p>
1575
1576<p>the -- noout is used to not output the resulting tree.</p>
1577
1578<p>The <code>--dtdvalid dtd</code> allows to validate the document(s) against
1579a given DTD.</p>
1580
1581<p>Libxml exports an API to handle DTDs and validation, check the <a
1582href="http://xmlsoft.org/html/libxml-valid.html">associated
1583description</a>.</p>
1584
1585<h3><a name="Other1">Other resources</a></h3>
1586
1587<p>DTDs are as old as SGML. So there may be a number of examples on-line, I
1588will just list one for now, others pointers welcome:</p>
1589<ul>
1590 <li><a href="http://www.xml101.com:8081/dtd/">XML-101 DTD</a></li>
1591</ul>
1592
1593<p>I suggest looking at the examples found under test/valid/dtd and any of
1594the large number of books available on XML. The dia example in test/valid
1595should be both simple and complete enough to allow you to build your own.</p>
1596
1597<p></p>
1598
1599<h2><a name="Memory">Memory Management</a></h2>
1600
1601<p>Table of Content:</p>
1602<ol>
1603 <li><a href="#General3">General overview</a></li>
Daniel Veillard9c466822001-10-25 12:03:39 +0000[diff] [blame]1604 <li><a href="#setting">Setting libxml set of memory routines</a></li>
Daniel Veillardb8cfbd12001-10-25 10:53:28 +0000[diff] [blame]1605 <li><a href="#cleanup">Cleaning up after parsing</a></li>
1606 <li><a href="#Debugging">Debugging routines</a></li>
1607 <li><a href="#General4">General memory requirements</a></li>
1608</ol>
1609
1610<h3><a name="General3">General overview</a></h3>
1611
1612<p>The module <code><a
1613href="http://xmlsoft.org/html/libxml-xmlmemory.html">xmlmemory.h</a></code>
1614provides the interfaces to the libxml memory system:</p>
1615<ul>
1616 <li>libxml does not use the libc memory allocator directly but xmlFree(),
1617 xmlMalloc() and xmlRealloc()</li>
1618 <li>those routines can be reallocated to a specific set of routine, by
1619 default the libc ones i.e. free(), malloc() and realloc()</li>
1620 <li>the xmlmemory.c module includes a set of debugging routine</li>
1621</ul>
1622
1623<h3><a name="setting">Setting libxml set of memory routines</a></h3>
1624
1625<p>It is sometimes useful to not use the default memory allocator, either for
1626debugging, analysis or to implement a specific behaviour on memory management
1627(like on embedded systems). Two function calls are available to do so:</p>
1628<ul>
1629 <li><a href="http://xmlsoft.org/html/libxml-xmlmemory.html">xmlMemGet ()</a>
1630 which return the current set of functions in use by the parser</li>
1631 <li><a
1632 href="http://xmlsoft.org/html/libxml-xmlmemory.html">xmlMemSetup()</a>
1633 which allow to set up a new set of memory allocation functions</li>
1634</ul>
1635
1636<p>Of course a call to xmlMemSetup() should probably be done before calling
1637any other libxml routines (unless you are sure your allocations routines are
1638compatibles).</p>
1639
1640<h3><a name="cleanup">Cleaning up after parsing</a></h3>
1641
1642<p>Libxml is not stateless, there is a few set of memory structures needing
1643allocation before the parser is fully functionnal (some encoding structures
1644for example). This also mean that once parsing is finished there is a tiny
1645amount of memory (a few hundred bytes) which can be recollected if you don't
1646reuse the parser immediately:</p>
1647<ul>
1648 <li><a href="http://xmlsoft.org/html/libxml-parser.html">xmlCleanupParser
1649 ()</a>
1650 is a centralized routine to free the parsing states. Note that it won't
1651 deallocate any produced tree if any (use the xmlFreeDoc() and related
1652 routines for this).</li>
1653 <li><a href="http://xmlsoft.org/html/libxml-parser.html">xmlInitParser
1654 ()</a>
1655 is the dual routine allowing to preallocate the parsing state which can
1656 be useful for example to avoid initialization reentrancy problems when
1657 using libxml in multithreaded applications</li>
1658</ul>
1659
1660<p>Generally xmlCleanupParser() is safe, if needed the state will be rebuild
1661at the next invocation of parser routines, but be careful of the consequences
1662in multithreaded applications.</p>
1663
1664<h3><a name="Debugging">Debugging routines</a></h3>
1665
1666<p>When configured using --with-mem-debug flag (off by default), libxml uses
1667a set of memory allocation debugging routineskeeping track of all allocated
1668blocks and the location in the code where the routine was called. A couple of
1669other debugging routines allow to dump the memory allocated infos to a file
1670or call a specific routine when a given block number is allocated:</p>
1671<ul>
1672 <li><a
1673 href="http://xmlsoft.org/html/libxml-xmlmemory.html">xmlMallocLoc()</a>
1674 <a
1675 href="http://xmlsoft.org/html/libxml-xmlmemory.html">xmlReallocLoc()</a>
1676 and <a
1677 href="http://xmlsoft.org/html/libxml-xmlmemory.html">xmlMemStrdupLoc()</a>
1678 are the memory debugging replacement allocation routines</li>
1679 <li><a href="http://xmlsoft.org/html/libxml-xmlmemory.html">xmlMemoryDump
1680 ()</a>
1681 dumps all the informations about the allocated memory block lefts in the
1682 <code>.memdump</code> file</li>
1683</ul>
1684
1685<p>When developping libxml memory debug is enabled, the tests programs call
1686xmlMemoryDump () and the "make test" regression tests will check for any
1687memory leak during the full regression test sequence, this helps a lot
1688ensuring that libxml does not leak memory and bullet proof memory
1689allocations use (some libc implementations are known to be far too permissive
1690resulting in major portability problems!).</p>
1691
1692<p>If the .memdump reports a leak, it displays the allocation function and
1693also tries to give some informations about the content and structure of the
1694allocated blocks left. This is sufficient in most cases to find the culprit,
1695but not always. Assuming the allocation problem is reproductible, it is
1696possible to find more easilly:</p>
1697<ol>
1698 <li>write down the block number xxxx not allocated</li>
1699 <li>export the environement variable XML_MEM_BREAKPOINT=xxxx</li>
1700 <li>run the program under a debugger and set a breakpoint on
1701 xmlMallocBreakpoint() a specific function called when this precise block
1702 is allocated</li>
1703 <li>when the breakpoint is reached you can then do a fine analysis of the
1704 allocation an step to see the condition resulting in the missing
1705 deallocation.</li>
1706</ol>
1707
1708<p>I used to use a commercial tool to debug libxml memory problems but after
1709noticing that it was not detecting memory leaks that simple mechanism was
1710used and proved extremely efficient until now.</p>
1711
1712<h3><a name="General4">General memory requirements</a></h3>
1713
1714<p>How much libxml memory require ? It's hard to tell in average it depends
1715of a number of things:</p>
1716<ul>
1717 <li>the parser itself should work in a fixed amout of memory, except for
1718 information maintained about the stacks of names and entities locations.
1719 The I/O and encoding handlers will probably account for a few KBytes.
1720 This is true for both the XML and HTML parser (though the HTML parser
1721 need more state).</li>
1722 <li>If you are generating the DOM tree then memory requirements will grow
1723 nearly lineary with the size of the data. In general for a balanced
1724 textual document the internal memory requirement is about 4 times the
1725 size of the UTF8 serialization of this document (exmple the XML-1.0
1726 recommendation is a bit more of 150KBytes and takes 650KBytes of main
1727 memory when parsed). Validation will add a amount of memory required for
1728 maintaining the external Dtd state which should be linear with the
1729 complexity of the content model defined by the Dtd</li>
1730 <li>If you don't care about the advanced features of libxml like
1731 validation, DOM, XPath or XPointer, but really need to work fixed memory
1732 requirements, then the SAX interface should be used.</li>
1733</ul>
1734
1735<p></p>
1736
1737<h2><a name="Encodings">Encodings support</a></h2>
1738
1739<p>Table of Content:</p>
1740<ol>
1741 <li><a href="encoding.html#What">What does internationalization support
1742 mean ?</a></li>
1743 <li><a href="encoding.html#internal">The internal encoding, how and
1744 why</a></li>
1745 <li><a href="encoding.html#implemente">How is it implemented ?</a></li>
1746 <li><a href="encoding.html#Default">Default supported encodings</a></li>
1747 <li><a href="encoding.html#extend">How to extend the existing
1748 support</a></li>
1749</ol>
1750
1751<h3><a name="What">What does internationalization support mean ?</a></h3>
1752
1753<p>XML was designed from the start to allow the support of any character set
1754by using Unicode. Any conformant XML parser has to support the UTF-8 and
1755UTF-16 default encodings which can both express the full unicode ranges. UTF8
1756is a variable length encoding whose greatest point are to resuse the same
1757emcoding for ASCII and to save space for Western encodings, but it is a bit
1758more complex to handle in practice. UTF-16 use 2 bytes per characters (and
1759sometimes combines two pairs), it makes implementation easier, but looks a
1760bit overkill for Western languages encoding. Moreover the XML specification
1761allows document to be encoded in other encodings at the condition that they
1762are clearly labelled as such. For example the following is a wellformed XML
1763document encoded in ISO-8859 1 and using accentuated letter that we French
1764likes for both markup and content:</p>
1765<pre>&lt;?xml version="1.0" encoding="ISO-8859-1"?&gt;
1766&lt;très&gt;là&lt;/très&gt;</pre>
1767
1768<p>Having internationalization support in libxml means the foolowing:</p>
1769<ul>
1770 <li>the document is properly parsed</li>
1771 <li>informations about it's encoding are saved</li>
1772 <li>it can be modified</li>
1773 <li>it can be saved in its original encoding</li>
1774 <li>it can also be saved in another encoding supported by libxml (for
1775 example straight UTF8 or even an ASCII form)</li>
1776</ul>
1777
1778<p>Another very important point is that the whole libxml API, with the
1779exception of a few routines to read with a specific encoding or save to a
1780specific encoding, is completely agnostic about the original encoding of the
1781document.</p>
1782
1783<p>It should be noted too that the HTML parser embedded in libxml now obbey
1784the same rules too, the following document will be (as of 2.2.2) handled in
1785an internationalized fashion by libxml too:</p>
1786<pre>&lt;!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN"
1787 "http://www.w3.org/TR/REC-html40/loose.dtd"&gt;
1788&lt;html lang="fr"&gt;
1789&lt;head&gt;
1790 &lt;META HTTP-EQUIV="Content-Type" CONTENT="text/html; charset=ISO-8859-1"&gt;
1791&lt;/head&gt;
1792&lt;body&gt;
1793&lt;p&gt;W3C crée des standards pour le Web.&lt;/body&gt;
1794&lt;/html&gt;</pre>
1795
1796<h3><a name="internal">The internal encoding, how and why</a></h3>
1797
1798<p>One of the core decision was to force all documents to be converted to a
1799default internal encoding, and that encoding to be UTF-8, here are the
1800rationale for those choices:</p>
1801<ul>
1802 <li>keeping the native encoding in the internal form would force the libxml
1803 users (or the code associated) to be fully aware of the encoding of the
1804 original document, for examples when adding a text node to a document,
1805 the content would have to be provided in the document encoding, i.e. the
1806 client code would have to check it before hand, make sure it's conformant
1807 to the encoding, etc ... Very hard in practice, though in some specific
1808 cases this may make sense.</li>
1809 <li>the second decision was which encoding. From the XML spec only UTF8 and
1810 UTF16 really makes sense as being the two only encodings for which there
1811 is amndatory support. UCS-4 (32 bits fixed size encoding) could be
1812 considered an intelligent choice too since it's a direct Unicode mapping
1813 support. I selected UTF-8 on the basis of efficiency and compatibility
1814 with surrounding software:
1815 <ul>
1816 <li>UTF-8 while a bit more complex to convert from/to (i.e. slightly
1817 more costly to import and export CPU wise) is also far more compact
1818 than UTF-16 (and UCS-4) for a majority of the documents I see it used
1819 for right now (RPM RDF catalogs, advogato data, various configuration
1820 file formats, etc.) and the key point for today's computer
1821 architecture is efficient uses of caches. If one nearly double the
1822 memory requirement to store the same amount of data, this will trash
1823 caches (main memory/external caches/internal caches) and my take is
1824 that this harms the system far more than the CPU requirements needed
1825 for the conversion to UTF-8</li>
1826 <li>Most of libxml version 1 users were using it with straight ASCII
1827 most of the time, doing the conversion with an internal encoding
1828 requiring all their code to be rewritten was a serious show-stopper
1829 for using UTF-16 or UCS-4.</li>
1830 <li>UTF-8 is being used as the de-facto internal encoding standard for
1831 related code like the <a href="http://www.pango.org/">pango</a>
1832 upcoming Gnome text widget, and a lot of Unix code (yep another place
1833 where Unix programmer base takes a different approach from Microsoft
1834 - they are using UTF-16)</li>
1835 </ul>
1836 </li>
1837</ul>
1838
1839<p>What does this mean in practice for the libxml user:</p>
1840<ul>
1841 <li>xmlChar, the libxml data type is a byte, those bytes must be assembled
1842 as UTF-8 valid strings. The proper way to terminate an xmlChar * string
1843 is simply to append 0 byte, as usual.</li>
1844 <li>One just need to make sure that when using chars outside the ASCII set,
1845 the values has been properly converted to UTF-8</li>
1846</ul>
1847
1848<h3><a name="implemente">How is it implemented ?</a></h3>
1849
1850<p>Let's describe how all this works within libxml, basically the I18N
1851(internationalization) support get triggered only during I/O operation, i.e.
1852when reading a document or saving one. Let's look first at the reading
1853sequence:</p>
1854<ol>
1855 <li>when a document is processed, we usually don't know the encoding, a
1856 simple heuristic allows to detect UTF-18 and UCS-4 from whose where the
1857 ASCII range (0-0x7F) maps with ASCII</li>
1858 <li>the xml declaration if available is parsed, including the encoding
1859 declaration. At that point, if the autodetected encoding is different
1860 from the one declared a call to xmlSwitchEncoding() is issued.</li>
1861 <li>If there is no encoding declaration, then the input has to be in either
1862 UTF-8 or UTF-16, if it is not then at some point when processing the
1863 input, the converter/checker of UTF-8 form will raise an encoding error.
1864 You may end-up with a garbled document, or no document at all ! Example:
1865 <pre>~/XML -&gt; ./xmllint err.xml
1866err.xml:1: error: Input is not proper UTF-8, indicate encoding !
1867&lt;très&gt;là&lt;/très&gt;
1868 ^
1869err.xml:1: error: Bytes: 0xE8 0x73 0x3E 0x6C
1870&lt;très&gt;là&lt;/très&gt;
1871 ^</pre>
1872 </li>
1873 <li>xmlSwitchEncoding() does an encoding name lookup, canonalize it, and
1874 then search the default registered encoding converters for that encoding.
1875 If it's not within the default set and iconv() support has been compiled
1876 it, it will ask iconv for such an encoder. If this fails then the parser
1877 will report an error and stops processing:
1878 <pre>~/XML -&gt; ./xmllint err2.xml
1879err2.xml:1: error: Unsupported encoding UnsupportedEnc
1880&lt;?xml version="1.0" encoding="UnsupportedEnc"?&gt;
1881 ^</pre>
1882 </li>
1883 <li>From that point the encoder process progressingly the input (it is
1884 plugged as a front-end to the I/O module) for that entity. It captures
1885 and convert on-the-fly the document to be parsed to UTF-8. The parser
1886 itself just does UTF-8 checking of this input and process it
1887 transparently. The only difference is that the encoding information has
1888 been added to the parsing context (more precisely to the input
1889 corresponding to this entity).</li>
1890 <li>The result (when using DOM) is an internal form completely in UTF-8
1891 with just an encoding information on the document node.</li>
1892</ol>
1893
1894<p>Ok then what's happen when saving the document (assuming you
1895colllected/built an xmlDoc DOM like structure) ? It depends on the function
1896called, xmlSaveFile() will just try to save in the original encoding, while
1897xmlSaveFileTo() and xmlSaveFileEnc() can optionally save to a given
1898encoding:</p>
1899<ol>
1900 <li>if no encoding is given, libxml will look for an encoding value
1901 associated to the document and if it exists will try to save to that
1902 encoding,
1903 <p>otherwise everything is written in the internal form, i.e. UTF-8</p>
1904 </li>
1905 <li>so if an encoding was specified, either at the API level or on the
1906 document, libxml will again canonalize the encoding name, lookup for a
1907 converter in the registered set or through iconv. If not found the
1908 function will return an error code</li>
1909 <li>the converter is placed before the I/O buffer layer, as another kind of
1910 buffer, then libxml will simply push the UTF-8 serialization to through
1911 that buffer, which will then progressively be converted and pushed onto
1912 the I/O layer.</li>
1913 <li>It is possible that the converter code fails on some input, for example
1914 trying to push an UTF-8 encoded chinese character through the UTF-8 to
1915 ISO-8859-1 converter won't work. Since the encoders are progressive they
1916 will just report the error and the number of bytes converted, at that
1917 point libxml will decode the offending character, remove it from the
1918 buffer and replace it with the associated charRef encoding &amp;#123; and
1919 resume the convertion. This guarante that any document will be saved
1920 without losses (except for markup names where this is not legal, this is
1921 a problem in the current version, in pactice avoid using non-ascci
1922 characters for tags or attributes names @@). A special "ascii" encoding
1923 name is used to save documents to a pure ascii form can be used when
1924 portability is really crucial</li>
1925</ol>
1926
1927<p>Here is a few examples based on the same test document:</p>
1928<pre>~/XML -&gt; ./xmllint isolat1
1929&lt;?xml version="1.0" encoding="ISO-8859-1"?&gt;
1930&lt;très&gt;là&lt;/très&gt;
1931~/XML -&gt; ./xmllint --encode UTF-8 isolat1
1932&lt;?xml version="1.0" encoding="UTF-8"?&gt;
1933&lt;très&gt;là  &lt;/très&gt;
1934~/XML -&gt; </pre>
1935
1936<p>The same processing is applied (and reuse most of the code) for HTML I18N
1937processing. Looking up and modifying the content encoding is a bit more
1938difficult since it is located in a &lt;meta&gt; tag under the &lt;head&gt;,
1939so a couple of functions htmlGetMetaEncoding() and htmlSetMetaEncoding() have
1940been provided. The parser also attempts to switch encoding on the fly when
1941detecting such a tag on input. Except for that the processing is the same
1942(and again reuses the same code).</p>
1943
1944<h3><a name="Default">Default supported encodings</a></h3>
1945
1946<p>libxml has a set of default converters for the following encodings
1947(located in encoding.c):</p>
1948<ol>
1949 <li>UTF-8 is supported by default (null handlers)</li>
1950 <li>UTF-16, both little and big endian</li>
1951 <li>ISO-Latin-1 (ISO-8859-1) covering most western languages</li>
1952 <li>ASCII, useful mostly for saving</li>
1953 <li>HTML, a specific handler for the conversion of UTF-8 to ASCII with HTML
1954 predefined entities like &amp;copy; for the Copyright sign.</li>
1955</ol>
1956
1957<p>More over when compiled on an Unix platfor with iconv support the full set
1958of encodings supported by iconv can be instantly be used by libxml. On a
1959linux machine with glibc-2.1 the list of supported encodings and aliases fill
19603 full pages, and include UCS-4, the full set of ISO-Latin encodings, and the
1961various Japanese ones.</p>
1962
1963<h4>Encoding aliases</h4>
1964
1965<p>From 2.2.3, libxml has support to register encoding names aliases. The
1966goal is to be able to parse document whose encoding is supported but where
1967the name differs (for example from the default set of names accepted by
1968iconv). The following functions allow to register and handle new aliases for
1969existing encodings. Once registered libxml will automatically lookup the
1970aliases when handling a document:</p>
1971<ul>
1972 <li>int xmlAddEncodingAlias(const char *name, const char *alias);</li>
1973 <li>int xmlDelEncodingAlias(const char *alias);</li>
1974 <li>const char * xmlGetEncodingAlias(const char *alias);</li>
1975 <li>void xmlCleanupEncodingAliases(void);</li>
1976</ul>
1977
1978<h3><a name="extend">How to extend the existing support</a></h3>
1979
1980<p>Well adding support for new encoding, or overriding one of the encoders
1981(assuming it is buggy) should not be hard, just write an input and output
1982conversion routines to/from UTF-8, and register them using
1983xmlNewCharEncodingHandler(name, xxxToUTF8, UTF8Toxxx), and they will be
1984called automatically if the parser(s) encounter such an encoding name
1985(register it uppercase, this will help). The description of the encoders,
1986their arguments and expected return values are described in the encoding.h
1987header.</p>
1988
1989<p>A quick note on the topic of subverting the parser to use a different
1990internal encoding than UTF-8, in some case people will absolutely want to
1991keep the internal encoding different, I think it's still possible (but the
1992encoding must be compliant with ASCII on the same subrange) though I didn't
1993tried it. The key is to override the default conversion routines (by
1994registering null encoders/decoders for your charsets), and bypass the UTF-8
1995checking of the parser by setting the parser context charset
1996(ctxt-&gt;charset) to something different than XML_CHAR_ENCODING_UTF8, but
1997there is no guarantee taht this will work. You may also have some troubles
1998saving back.</p>
1999
2000<p>Basically proper I18N support is important, this requires at least
2001libxml-2.0.0, but a lot of features and corrections are really available only
2002starting 2.2.</p>
2003
2004<h2><a name="IO">I/O Interfaces</a></h2>
2005
2006<p>Table of Content:</p>
2007<ol>
2008 <li><a href="#General1">General overview</a></li>
2009 <li><a href="#basic">The basic buffer type</a></li>
2010 <li><a href="#Input">Input I/O handlers</a></li>
2011 <li><a href="#Output">Output I/O handlers</a></li>
2012 <li><a href="#entities">The entities loader</a></li>
2013 <li><a href="#Example2">Example of customized I/O</a></li>
2014</ol>
2015
2016<h3><a name="General1">General overview</a></h3>
2017
2018<p>The module <code><a
2019href="http://xmlsoft.org/html/libxml-xmlio.html">xmlIO.h</a></code> provides
2020the interfaces to the libxml I/O system. This consists of 4 main parts:</p>
2021<ul>
2022 <li>Entities loader, this is a routine which tries to fetch the entities
2023 (files) based on their PUBLIC and SYSTEM identifiers. The default loader
2024 don't look at the public identifier since libxml do not maintain a
2025 catalog. You can redefine you own entity loader by using
2026 <code>xmlGetExternalEntityLoader()</code> and
Daniel Veillard9c466822001-10-25 12:03:39 +0000[diff] [blame]2027 <code>xmlSetExternalEntityLoader()</code>. <a href="#entities">Check the
2028 example</a>.</li>
Daniel Veillardb8cfbd12001-10-25 10:53:28 +0000[diff] [blame]2029 <li>Input I/O buffers which are a commodity structure used by the parser(s)
2030 input layer to handle fetching the informations to feed the parser. This
2031 provides buffering and is also a placeholder where the encoding
2032 convertors to UTF8 are piggy-backed.</li>
2033 <li>Output I/O buffers are similar to the Input ones and fulfill similar
2034 task but when generating a serialization from a tree.</li>
2035 <li>A mechanism to register sets of I/O callbacks and associate them with
2036 specific naming schemes like the protocol part of the URIs.
2037 <p>This affect the default I/O operations and allows to use specific I/O
2038 handlers for certain names.</p>
2039 </li>
2040</ul>
2041
2042<p>The general mechanism used when loading http://rpmfind.net/xml.html for
2043example in the HTML parser is the following:</p>
2044<ol>
2045 <li>The default entity loader calls <code>xmlNewInputFromFile()</code> with
2046 the parsing context and the URI string.</li>
2047 <li>the URI string is checked against the existing registered handlers
2048 using their match() callback function, if the HTTP module was compiled
2049 in, it is registered and its match() function will succeeds</li>
2050 <li>the open() function of the handler is called and if successful will
2051 return an I/O Input buffer</li>
2052 <li>the parser will the start reading from this buffer and progressively
2053 fetch information from the resource, calling the read() function of the
2054 handler until the resource is exhausted</li>
2055 <li>if an encoding change is detected it will be installed on the input
2056 buffer, providing buffering and efficient use of the conversion
2057 routines</li>
2058 <li>once the parser has finished, the close() function of the handler is
2059 called once and the Input buffer and associed resources are
2060 deallocated.</li>
2061</ol>
2062
2063<p>The user defined callbacks are checked first to allow overriding of the
2064default libxml I/O routines.</p>
2065
2066<h3><a name="basic">The basic buffer type</a></h3>
2067
2068<p>All the buffer manipulation handling is done using the
2069<code>xmlBuffer</code> type define in <code><a
2070href="http://xmlsoft.org/html/libxml-tree.html">tree.h</a> </code>which is a
2071resizable memory buffer. The buffer allocation strategy can be selected to be
2072either best-fit or use an exponential doubling one (CPU vs. memory use
2073tradeoff). The values are <code>XML_BUFFER_ALLOC_EXACT</code> and
2074<code>XML_BUFFER_ALLOC_DOUBLEIT</code>, and can be set individually or on a
2075system wide basis using <code>xmlBufferSetAllocationScheme()</code>. A number
2076of functions allows to manipulate buffers with names starting with the
2077<code>xmlBuffer...</code> prefix.</p>
2078
2079<h3><a name="Input">Input I/O handlers</a></h3>
2080
2081<p>An Input I/O handler is a simple structure
2082<code>xmlParserInputBuffer</code> containing a context associated to the
2083resource (file descriptor, or pointer to a protocol handler), the read() and
2084close() callbacks to use and an xmlBuffer. And extra xmlBuffer and a charset
2085encoding handler are also present to support charset conversion when
2086needed.</p>
2087
2088<h3><a name="Output">Output I/O handlers</a></h3>
2089
2090<p>An Output handler <code>xmlOutputBuffer</code> is completely similar to an
2091Input one except the callbacks are write() and close().</p>
2092
2093<h3><a name="entities">The entities loader</a></h3>
2094
2095<p>The entity loader resolves requests for new entities and create inputs for
2096the parser. Creating an input from a filename or an URI string is done
2097through the xmlNewInputFromFile() routine. The default entity loader do not
2098handle the PUBLIC identifier associated with an entity (if any). So it just
2099calls xmlNewInputFromFile() with the SYSTEM identifier (which is mandatory in
2100XML).</p>
2101
2102<p>If you want to hook up a catalog mechanism then you simply need to
2103override the default entity loader, here is an example:</p>
2104<pre>#include &lt;libxml/xmlIO.h&gt;
2105
2106xmlExternalEntityLoader defaultLoader = NULL;
2107
2108xmlParserInputPtr
2109xmlMyExternalEntityLoader(const char *URL, const char *ID,
2110 xmlParserCtxtPtr ctxt) {
2111 xmlParserInputPtr ret;
2112 const char *fileID = NULL;
2113 /* lookup for the fileID depending on ID */
2114
2115 ret = xmlNewInputFromFile(ctxt, fileID);
2116 if (ret != NULL)
2117 return(ret);
2118 if (defaultLoader != NULL)
2119 ret = defaultLoader(URL, ID, ctxt);
2120 return(ret);
2121}
2122
2123int main(..) {
2124 ...
2125
2126 /*
2127 * Install our own entity loader
2128 */
2129 defaultLoader = xmlGetExternalEntityLoader();
2130 xmlSetExternalEntityLoader(xmlMyExternalEntityLoader);
2131
2132 ...
2133}</pre>
2134
2135<h3><a name="Example2">Example of customized I/O</a></h3>
2136
2137<p>This example come from <a href="http://xmlsoft.org/messages/0708.html">a
2138real use case</a>, xmlDocDump() closes the FILE * passed by the application
2139and this was a problem. The <a
2140href="http://xmlsoft.org/messages/0711.html">solution</a> was to redefine a
2141new output handler with the closing call deactivated:</p>
2142<ol>
2143 <li>First define a new I/O ouput allocator where the output don't close the
2144 file:
2145 <pre>xmlOutputBufferPtr
2146xmlOutputBufferCreateOwn(FILE *file, xmlCharEncodingHandlerPtr encoder) {
2147    xmlOutputBufferPtr ret;
2148    
2149    if (xmlOutputCallbackInitialized == 0)
2150        xmlRegisterDefaultOutputCallbacks();
2151
2152    if (file == NULL) return(NULL);
2153    ret = xmlAllocOutputBuffer(encoder);
2154    if (ret != NULL) {
2155        ret-&gt;context = file;
2156        ret-&gt;writecallback = xmlFileWrite;
2157        ret-&gt;closecallback = NULL; /* No close callback */
2158    }
2159    return(ret); <br>
2160
2161
2162
Daniel Veillard9c466822001-10-25 12:03:39 +0000[diff] [blame]2163
2164
Daniel Veillardc6271d22001-10-27 07:50:58 +0000[diff] [blame]2165
Daniel Veillard51095312001-10-28 18:51:57 +0000[diff] [blame]2166
Daniel Veillard52dcab32001-10-30 12:51:17 +0000[diff] [blame]2167
Daniel Veillarded421aa2001-11-04 21:22:45 +0000[diff] [blame]2168
Daniel Veillard43d3f612001-11-10 11:57:23 +0000[diff] [blame^]2169
Daniel Veillardb8cfbd12001-10-25 10:53:28 +0000[diff] [blame]2170} </pre>
2171 </li>
2172 <li>And then use it to save the document:
2173 <pre>FILE *f;
2174xmlOutputBufferPtr output;
2175xmlDocPtr doc;
2176int res;
2177
2178f = ...
2179doc = ....
2180
2181output = xmlOutputBufferCreateOwn(f, NULL);
2182res = xmlSaveFileTo(output, doc, NULL);
2183 </pre>
2184 </li>
2185</ol>
2186
2187<h2><a name="Catalog">Catalog support</a></h2>
2188
2189<p>Table of Content:</p>
2190<ol>
2191 <li><a href="General2">General overview</a></li>
2192 <li><a href="#definition">The definition</a></li>
2193 <li><a href="#Simple">Using catalogs</a></li>
2194 <li><a href="#Some">Some examples</a></li>
2195 <li><a href="#reference">How to tune catalog usage</a></li>
2196 <li><a href="#validate">How to debug catalog processing</a></li>
2197 <li><a href="#Declaring">How to create and maintain catalogs</a></li>
2198 <li><a href="#implemento">The implementor corner quick review of the
2199 API</a></li>
2200 <li><a href="#Other">Other resources</a></li>
2201</ol>
2202
2203<h3><a name="General2">General overview</a></h3>
2204
2205<p>What is a catalog? Basically it's a lookup mechanism used when an entity
2206(a file or a remote resource) references another entity. The catalog lookup
2207is inserted between the moment the reference is recognized by the software
2208(XML parser, stylesheet processing, or even images referenced for inclusion
2209in a rendering) and the time where loading that resource is actually
2210started.</p>
2211
2212<p>It is basically used for 3 things:</p>
2213<ul>
2214 <li>mapping from "logical" names, the public identifiers and a more
2215 concrete name usable for download (and URI). For example it can associate
2216 the logical name
2217 <p>"-//OASIS//DTD DocBook XML V4.1.2//EN"</p>
2218 <p>of the DocBook 4.1.2 XML DTD with the actual URL where it can be
2219 downloaded</p>
2220 <p>http://www.oasis-open.org/docbook/xml/4.1.2/docbookx.dtd</p>
2221 </li>
2222 <li>remapping from a given URL to another one, like an HTTP indirection
2223 saying that
2224 <p>"http://www.oasis-open.org/committes/tr.xsl"</p>
2225 <p>should really be looked at</p>
2226 <p>"http://www.oasis-open.org/committes/entity/stylesheets/base/tr.xsl"</p>
2227 </li>
2228 <li>providing a local cache mechanism allowing to load the entities
2229 associated to public identifiers or remote resources, this is a really
2230 important feature for any significant deployment of XML or SGML since it
2231 allows to avoid the aleas and delays associated to fetching remote
2232 resources.</li>
2233</ul>
2234
2235<h3><a name="definition">The definitions</a></h3>
2236
2237<p>Libxml, as of 2.4.3 implements 2 kind of catalogs:</p>
2238<ul>
2239 <li>the older SGML catalogs, the official spec is SGML Open Technical
2240 Resolution TR9401:1997, but is better understood by reading <a
2241 href="http://www.jclark.com/sp/catalog.htm">the SP Catalog page</a> from
2242 James Clark. This is relatively old and not the preferred mode of
2243 operation of libxml.</li>
2244 <li><a href="http://www.oasis-open.org/committees/entity/spec.html">XML
2245 Catalogs</a>
2246 is far more flexible, more recent, uses an XML syntax and should scale
2247 quite better. This is the default option of libxml.</li>
2248</ul>
2249
2250<p></p>
2251
2252<h3><a name="Simple">Using catalog</a></h3>
2253
2254<p>In a normal environment libxml will by default check the presence of a
2255catalog in /etc/xml/catalog, and assuming it has been correctly populated,
2256the processing is completely transparent to the document user. To take a
2257concrete example, suppose you are authoring a DocBook document, this one
2258starts with the following DOCTYPE definition:</p>
2259<pre>&lt;?xml version='1.0'?&gt;
2260&lt;!DOCTYPE book PUBLIC "-//Norman Walsh//DTD DocBk XML V3.1.4//EN"
2261 "http://nwalsh.com/docbook/xml/3.1.4/db3xml.dtd"&gt;</pre>
2262
2263<p>When validating the document with libxml, the catalog will be
2264automatically consulted to lookup the public identifier "-//Norman Walsh//DTD
2265DocBk XML V3.1.4//EN" and the system identifier
2266"http://nwalsh.com/docbook/xml/3.1.4/db3xml.dtd", and if these entities have
2267been installed on your system and the catalogs actually point to them, libxml
2268will fetch them from the local disk.</p>
2269
2270<p style="font-size: 10pt"><strong>Note</strong>: Really don't use this
2271DOCTYPE example it's a really old version, but is fine as an example.</p>
2272
2273<p>Libxml will check the catalog each time that it is requested to load an
2274entity, this includes DTD, external parsed entities, stylesheets, etc ... If
2275your system is correctly configured all the authoring phase and processing
2276should use only local files, even if your document stays portable because it
2277uses the canonical public and system ID, referencing the remote document.</p>
2278
2279<h3><a name="Some">Some examples:</a></h3>
2280
2281<p>Here is a couple of fragments from XML Catalogs used in libxml early
2282regression tests in <code>test/catalogs</code> :</p>
2283<pre>&lt;?xml version="1.0"?&gt;
2284&lt;!DOCTYPE catalog PUBLIC
2285 "-//OASIS//DTD Entity Resolution XML Catalog V1.0//EN"
2286 "http://www.oasis-open.org/committees/entity/release/1.0/catalog.dtd"&gt;
2287&lt;catalog xmlns="urn:oasis:names:tc:entity:xmlns:xml:catalog"&gt;
2288 &lt;public publicId="-//OASIS//DTD DocBook XML V4.1.2//EN"
2289 uri="http://www.oasis-open.org/docbook/xml/4.1.2/docbookx.dtd"/&gt;
2290...</pre>
2291
2292<p>This is the beginning of a catalog for DocBook 4.1.2, XML Catalogs are
2293written in XML, there is a specific namespace for catalog elements
2294"urn:oasis:names:tc:entity:xmlns:xml:catalog". The first entry in this
2295catalog is a <code>public</code> mapping it allows to associate a Public
2296Identifier with an URI.</p>
2297<pre>...
2298 &lt;rewriteSystem systemIdStartString="http://www.oasis-open.org/docbook/"
2299 rewritePrefix="file:///usr/share/xml/docbook/"/&gt;
2300...</pre>
2301
2302<p>A <code>rewriteSystem</code> is a very powerful instruction, it says that
2303any URI starting with a given prefix should be looked at another URI
2304constructed by replacing the prefix with an new one. In effect this acts like
2305a cache system for a full area of the Web. In practice it is extremely useful
2306with a file prefix if you have installed a copy of those resources on your
2307local system.</p>
2308<pre>...
2309&lt;delegatePublic publicIdStartString="-//OASIS//DTD XML Catalog //"
2310 catalog="file:///usr/share/xml/docbook.xml"/&gt;
2311&lt;delegatePublic publicIdStartString="-//OASIS//ENTITIES DocBook XML"
2312 catalog="file:///usr/share/xml/docbook.xml"/&gt;
2313&lt;delegatePublic publicIdStartString="-//OASIS//DTD DocBook XML"
2314 catalog="file:///usr/share/xml/docbook.xml"/&gt;
2315&lt;delegateSystem systemIdStartString="http://www.oasis-open.org/docbook/"
2316 catalog="file:///usr/share/xml/docbook.xml"/&gt;
2317&lt;delegateURI uriStartString="http://www.oasis-open.org/docbook/"
2318 catalog="file:///usr/share/xml/docbook.xml"/&gt;
2319...</pre>
2320
2321<p>Delegation is the core features which allows to build a tree of catalogs,
2322easier to maintain than a single catalog, based on Public Identifier, System
2323Identifier or URI prefixes it instructs the catalog software to look up
2324entries in another resource. This feature allow to build hierarchies of
2325catalogs, the set of entries presented should be sufficient to redirect the
2326resolution of all DocBook references to the specific catalog in
2327<code>/usr/share/xml/docbook.xml</code> this one in turn could delegate all
2328references for DocBook 4.2.1 to a specific catalog installed at the same time
2329as the DocBook resources on the local machine.</p>
2330
2331<h3><a name="reference">How to tune catalog usage:</a></h3>
2332
2333<p>The user can change the default catalog behaviour by redirecting queries
2334to its own set of catalogs, this can be done by setting the
2335<code>XML_CATALOG_FILES</code> environment variable to a list of catalogs, an
2336empty one should deactivate loading the default <code>/etc/xml/catalog</code>
2337default catalog</p>
2338
2339<h3><a name="validate">How to debug catalog processing:</a></h3>
2340
2341<p>Setting up the <code>XML_DEBUG_CATALOG</code> environment variable will
2342make libxml output debugging informations for each catalog operations, for
2343example:</p>
2344<pre>orchis:~/XML -&gt; xmllint --memory --noout test/ent2
2345warning: failed to load external entity "title.xml"
2346orchis:~/XML -&gt; export XML_DEBUG_CATALOG=
2347orchis:~/XML -&gt; xmllint --memory --noout test/ent2
2348Failed to parse catalog /etc/xml/catalog
2349Failed to parse catalog /etc/xml/catalog
2350warning: failed to load external entity "title.xml"
2351Catalogs cleanup
2352orchis:~/XML -&gt; </pre>
2353
2354<p>The test/ent2 references an entity, running the parser from memory makes
2355the base URI unavailable and the the "title.xml" entity cannot be loaded.
2356Setting up the debug environment variable allows to detect that an attempt is
2357made to load the <code>/etc/xml/catalog</code> but since it's not present the
2358resolution fails.</p>
2359
2360<p>But the most advanced way to debug XML catalog processing is to use the
2361<strong>xmlcatalog</strong> command shipped with libxml2, it allows to load
2362catalogs and make resolution queries to see what is going on. This is also
2363used for the regression tests:</p>
2364<pre>orchis:~/XML -&gt; ./xmlcatalog test/catalogs/docbook.xml \
2365 "-//OASIS//DTD DocBook XML V4.1.2//EN"
2366http://www.oasis-open.org/docbook/xml/4.1.2/docbookx.dtd
2367orchis:~/XML -&gt; </pre>
2368
2369<p>For debugging what is going on, adding one -v flags increase the verbosity
2370level to indicate the processing done (adding a second flag also indicate
2371what elements are recognized at parsing):</p>
2372<pre>orchis:~/XML -&gt; ./xmlcatalog -v test/catalogs/docbook.xml \
2373 "-//OASIS//DTD DocBook XML V4.1.2//EN"
2374Parsing catalog test/catalogs/docbook.xml's content
2375Found public match -//OASIS//DTD DocBook XML V4.1.2//EN
2376http://www.oasis-open.org/docbook/xml/4.1.2/docbookx.dtd
2377Catalogs cleanup
2378orchis:~/XML -&gt; </pre>
2379
2380<p>A shell interface is also available to debug and process multiple queries
2381(and for regression tests):</p>
2382<pre>orchis:~/XML -&gt; ./xmlcatalog -shell test/catalogs/docbook.xml \
2383 "-//OASIS//DTD DocBook XML V4.1.2//EN"
2384&gt; help
2385Commands available:
2386public PublicID: make a PUBLIC identifier lookup
2387system SystemID: make a SYSTEM identifier lookup
2388resolve PublicID SystemID: do a full resolver lookup
2389add 'type' 'orig' 'replace' : add an entry
2390del 'values' : remove values
2391dump: print the current catalog state
2392debug: increase the verbosity level
2393quiet: decrease the verbosity level
2394exit: quit the shell
2395&gt; public "-//OASIS//DTD DocBook XML V4.1.2//EN"
2396http://www.oasis-open.org/docbook/xml/4.1.2/docbookx.dtd
2397&gt; quit
2398orchis:~/XML -&gt; </pre>
2399
2400<p>This should be sufficient for most debugging purpose, this was actually
2401used heavily to debug the XML Catalog implementation itself.</p>
2402
2403<h3><a name="Declaring">How to create and maintain</a> catalogs:</h3>
2404
2405<p>Basically XML Catalogs are XML files, you can either use XML tools to
2406manage them or use <strong>xmlcatalog</strong> for this. The basic step is
2407to create a catalog the -create option provide this facility:</p>
2408<pre>orchis:~/XML -&gt; ./xmlcatalog --create tst.xml
2409&lt;?xml version="1.0"?&gt;
2410&lt;!DOCTYPE catalog PUBLIC "-//OASIS//DTD Entity Resolution XML Catalog V1.0//EN"
2411 "http://www.oasis-open.org/committees/entity/release/1.0/catalog.dtd"&gt;
2412&lt;catalog xmlns="urn:oasis:names:tc:entity:xmlns:xml:catalog"/&gt;
2413orchis:~/XML -&gt; </pre>
2414
2415<p>By default xmlcatalog does not overwrite the original catalog and save the
2416result on the standard output, this can be overridden using the -noout
2417option. The <code>-add</code> command allows to add entries in the
2418catalog:</p>
2419<pre>orchis:~/XML -&gt; ./xmlcatalog --noout --create --add "public" \
2420 "-//OASIS//DTD DocBook XML V4.1.2//EN" \
2421 http://www.oasis-open.org/docbook/xml/4.1.2/docbookx.dtd tst.xml
2422orchis:~/XML -&gt; cat tst.xml
2423&lt;?xml version="1.0"?&gt;
2424&lt;!DOCTYPE catalog PUBLIC "-//OASIS//DTD Entity Resolution XML Catalog V1.0//EN" \
2425 "http://www.oasis-open.org/committees/entity/release/1.0/catalog.dtd"&gt;
2426&lt;catalog xmlns="urn:oasis:names:tc:entity:xmlns:xml:catalog"&gt;
2427&lt;public publicId="-//OASIS//DTD DocBook XML V4.1.2//EN"
2428 uri="http://www.oasis-open.org/docbook/xml/4.1.2/docbookx.dtd"/&gt;
2429&lt;/catalog&gt;
2430orchis:~/XML -&gt; </pre>
2431
2432<p>The <code>-add</code> option will always take 3 parameters even if some of
2433the XML Catalog constructs (like nextCatalog) will have only a single
2434argument, just pass a third empty string, it will be ignored.</p>
2435
2436<p>Similarly the <code>-del</code> option remove matching entries from the
2437catalog:</p>
2438<pre>orchis:~/XML -&gt; ./xmlcatalog --del \
2439 "http://www.oasis-open.org/docbook/xml/4.1.2/docbookx.dtd" tst.xml
2440&lt;?xml version="1.0"?&gt;
2441&lt;!DOCTYPE catalog PUBLIC "-//OASIS//DTD Entity Resolution XML Catalog V1.0//EN"
2442 "http://www.oasis-open.org/committees/entity/release/1.0/catalog.dtd"&gt;
2443&lt;catalog xmlns="urn:oasis:names:tc:entity:xmlns:xml:catalog"/&gt;
2444orchis:~/XML -&gt; </pre>
2445
2446<p>The catalog is now empty. Note that the matching of <code>-del</code> is
2447exact and would have worked in a similar fashion with the Public ID
2448string.</p>
2449
2450<p>This is rudimentary but should be sufficient to manage a not too complex
2451catalog tree of resources.</p>
2452
2453<h3><a name="implemento">The implementor corner quick review of the
2454API:</a></h3>
2455
2456<p>First, and like for every other module of libxml, there is an
2457automatically generated <a href="html/libxml-catalog.html">API page for
2458catalog support</a>.</p>
2459
2460<p>The header for the catalog interfaces should be included as:</p>
2461<pre>#include &lt;libxml/catalog.h&gt;</pre>
2462
2463<p>The API is voluntarily kept very simple. First it is not obvious that
2464applications really need access to it since it is the default behaviour of
2465libxml (Note: it is possible to completely override libxml default catalog by
2466using <a href="html/libxml-parser.html">xmlSetExternalEntityLoader</a> to
2467plug an application specific resolver).</p>
2468
2469<p>Basically libxml support 2 catalog lists:</p>
2470<ul>
2471 <li>the default one, global shared by all the application</li>
2472 <li>a per-document catalog, this one is built if the document uses the
2473 <code>oasis-xml-catalog</code> PIs to specify its own catalog list, it is
2474 associated to the parser context and destroyed when the parsing context
2475 is destroyed.</li>
2476</ul>
2477
2478<p>the document one will be used first if it exists.</p>
2479
2480<h4>Initialization routines:</h4>
2481
2482<p>xmlInitializeCatalog(), xmlLoadCatalog() and xmlLoadCatalogs() should be
2483used at startup to initialize the catalog, if the catalog should be
2484initialized with specific values xmlLoadCatalog() or xmlLoadCatalogs()
2485should be called before xmlInitializeCatalog() which would otherwise do a
2486default initialization first.</p>
2487
2488<p>The xmlCatalogAddLocal() call is used by the parser to grow the document
2489own catalog list if needed.</p>
2490
2491<h4>Preferences setup:</h4>
2492
2493<p>The XML Catalog spec requires the possibility to select default
2494preferences between public and system delegation,
2495xmlCatalogSetDefaultPrefer() allows this, xmlCatalogSetDefaults() and
2496xmlCatalogGetDefaults() allow to control if XML Catalogs resolution should
2497be forbidden, allowed for global catalog, for document catalog or both, the
2498default is to allow both.</p>
2499
2500<p>And of course xmlCatalogSetDebug() allows to generate debug messages
2501(through the xmlGenericError() mechanism).</p>
2502
2503<h4>Querying routines:</h4>
2504
2505<p>xmlCatalogResolve(), xmlCatalogResolveSystem(), xmlCatalogResolvePublic()
2506and xmlCatalogResolveURI() are relatively explicit if you read the XML
2507Catalog specification they correspond to section 7 algorithms, they should
2508also work if you have loaded an SGML catalog with a simplified semantic.</p>
2509
2510<p>xmlCatalogLocalResolve() and xmlCatalogLocalResolveURI() are the same but
2511operate on the document catalog list</p>
2512
2513<h4>Cleanup and Miscellaneous:</h4>
2514
2515<p>xmlCatalogCleanup() free-up the global catalog, xmlCatalogFreeLocal() is
2516the per-document equivalent.</p>
2517
2518<p>xmlCatalogAdd() and xmlCatalogRemove() are used to dynamically modify the
2519first catalog in the global list, and xmlCatalogDump() allows to dump a
2520catalog state, those routines are primarily designed for xmlcatalog, I'm not
2521sure that exposing more complex interfaces (like navigation ones) would be
2522really useful.</p>
2523
2524<p>The xmlParseCatalogFile() is a function used to load XML Catalog files,
2525it's similar as xmlParseFile() except it bypass all catalog lookups, it's
2526provided because this functionality may be useful for client tools.</p>
2527
2528<h4>threaded environments:</h4>
2529
2530<p>Since the catalog tree is built progressively, some care has been taken to
2531try to avoid troubles in multithreaded environments. The code is now thread
2532safe assuming that the libxml library has been compiled with threads
2533support.</p>
2534
2535<p></p>
2536
2537<h3><a name="Other">Other resources</a></h3>
2538
2539<p>The XML Catalog specification is relatively recent so there isn't much
2540literature to point at:</p>
2541<ul>
2542 <li>You can find an good rant from Norm Walsh about <a
2543 href="http://www.arbortext.com/Think_Tank/XML_Resources/Issue_Three/issue_three.html">the
2544 need for catalogs</a>, it provides a lot of context informations even if
2545 I don't agree with everything presented.</li>
2546 <li>An <a href="http://home.ccil.org/~cowan/XML/XCatalog.html">old XML
2547 catalog proposal</a> from John Cowan</li>
2548 <li>The <a href="http://www.rddl.org/">Resource Directory Description
2549 Language</a> (RDDL) another catalog system but more oriented toward
2550 providing metadata for XML namespaces.</li>
2551 <li>the page from the OASIS Technical <a
2552 href="http://www.oasis-open.org/committees/entity/">Committee on Entity
2553 Resolution</a> who maintains XML Catalog, you will find pointers to the
2554 specification update, some background and pointers to others tools
2555 providing XML Catalog support</li>
2556 <li>I have uploaded <a href="ftp://xmlsoft.org/test/dbk412catalog.tar.gz">a
2557 mall tarball</a> containing XML Catalogs for DocBook 4.1.2 which seems to
2558 work fine for me</li>
2559 <li>The <a href="http://www.xmlsoft.org/xmlcatalog_man.html">xmlcatalog
2560 manual page</a></li>
2561</ul>
2562
2563<p>If you have suggestions for corrections or additions, simply contact
2564me:</p>
2565
2566<h2><a name="library">The parser interfaces</a></h2>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2567
2568<p>This section is directly intended to help programmers getting bootstrapped
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]2569using the XML library from the C language. It is not intended to be
2570extensive. I hope the automatically generated documents will provide the
2571completeness required, but as a separate set of documents. The interfaces of
2572the XML library are by principle low level, there is nearly zero abstraction.
2573Those interested in a higher level API should <a href="#DOM">look at
2574DOM</a>.</p>
Daniel Veillardccb09631998-10-27 06:21:04 +0000[diff] [blame]2575
Daniel Veillard9cb5ff42001-01-29 08:22:21 +0000[diff] [blame]2576<p>The <a href="html/libxml-parser.html">parser interfaces for XML</a> are
2577separated from the <a href="html/libxml-htmlparser.html">HTML parser
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]2578interfaces</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]2579
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]2580<h3><a name="Invoking">Invoking the parser : the pull method</a></h3>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2581
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]2582<p>Usually, the first thing to do is to read an XML input. The parser accepts
2583documents either from in-memory strings or from files. The functions are
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2584defined in "parser.h":</p>
Daniel Veillard10c6a8f1998-10-28 01:00:12 +0000[diff] [blame]2585<dl>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2586 <dt><code>xmlDocPtr xmlParseMemory(char *buffer, int size);</code></dt>
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]2587 <dd><p>Parse a null-terminated string containing the document.</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2588 </dd>
Daniel Veillard10c6a8f1998-10-28 01:00:12 +0000[diff] [blame]2589</dl>
2590<dl>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2591 <dt><code>xmlDocPtr xmlParseFile(const char *filename);</code></dt>
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]2592 <dd><p>Parse an XML document contained in a (possibly compressed)
2593 file.</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2594 </dd>
Daniel Veillard10c6a8f1998-10-28 01:00:12 +0000[diff] [blame]2595</dl>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2596
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]2597<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]2598failure).</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2599
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]2600<h3 id="Invoking1">Invoking the parser: the push method</h3>
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]2601
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]2602<p>In order for the application to keep the control when the document is
2603being fetched (which is common for GUI based programs) libxml provides a push
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]2604interface, too, as of version 1.8.3. Here are the interface functions:</p>
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]2605<pre>xmlParserCtxtPtr xmlCreatePushParserCtxt(xmlSAXHandlerPtr sax,
2606 void *user_data,
2607 const char *chunk,
2608 int size,
2609 const char *filename);
2610int xmlParseChunk (xmlParserCtxtPtr ctxt,
2611 const char *chunk,
2612 int size,
2613 int terminate);</pre>
2614
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]2615<p>and here is a simple example showing how to use the interface:</p>
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]2616<pre> FILE *f;
2617
2618 f = fopen(filename, "r");
2619 if (f != NULL) {
2620 int res, size = 1024;
2621 char chars[1024];
2622 xmlParserCtxtPtr ctxt;
2623
2624 res = fread(chars, 1, 4, f);
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]2625 if (res &gt; 0) {
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]2626 ctxt = xmlCreatePushParserCtxt(NULL, NULL,
2627 chars, res, filename);
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]2628 while ((res = fread(chars, 1, size, f)) &gt; 0) {
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]2629 xmlParseChunk(ctxt, chars, res, 0);
2630 }
2631 xmlParseChunk(ctxt, chars, 0, 1);
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]2632 doc = ctxt-&gt;myDoc;
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]2633 xmlFreeParserCtxt(ctxt);
2634 }
2635 }</pre>
2636
Daniel Veillardec70e912001-02-26 20:10:45 +0000[diff] [blame]2637<p>The HTML parser embedded into libxml also has a push interface; the
2638functions are just prefixed by "html" rather than "xml".</p>
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]2639
2640<h3 id="Invoking2">Invoking the parser: the SAX interface</h3>
2641
Daniel Veillardec70e912001-02-26 20:10:45 +0000[diff] [blame]2642<p>The tree-building interface makes the parser memory-hungry, first loading
2643the document in memory and then building the tree itself. Reading a document
2644without building the tree is possible using the SAX interfaces (see SAX.h and
2645<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]2646Henstridge's documentation</a>). Note also that the push interface can be
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]2647limited to SAX: just use the two first arguments of
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]2648<code>xmlCreatePushParserCtxt()</code>.</p>
Daniel Veillardccb09631998-10-27 06:21:04 +0000[diff] [blame]2649
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]2650<h3><a name="Building">Building a tree from scratch</a></h3>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2651
2652<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]2653there is a set of functions dedicated to building new elements. (These are
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]2654also described in &lt;libxml/tree.h&gt;.) For example, here is a piece of
2655code that produces the XML document used in the previous examples:</p>
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]2656<pre> #include &lt;libxml/tree.h&gt;
Daniel Veillard361d8452000-04-03 19:48:13 +0000[diff] [blame]2657 xmlDocPtr doc;
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]2658 xmlNodePtr tree, subtree;
2659
2660 doc = xmlNewDoc("1.0");
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]2661 doc-&gt;children = xmlNewDocNode(doc, NULL, "EXAMPLE", NULL);
2662 xmlSetProp(doc-&gt;children, "prop1", "gnome is great");
2663 xmlSetProp(doc-&gt;children, "prop2", "&amp; linux too");
2664 tree = xmlNewChild(doc-&gt;children, NULL, "head", NULL);
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]2665 subtree = xmlNewChild(tree, NULL, "title", "Welcome to Gnome");
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]2666 tree = xmlNewChild(doc-&gt;children, NULL, "chapter", NULL);
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]2667 subtree = xmlNewChild(tree, NULL, "title", "The Linux adventure");
2668 subtree = xmlNewChild(tree, NULL, "p", "bla bla bla ...");
2669 subtree = xmlNewChild(tree, NULL, "image", NULL);
2670 xmlSetProp(subtree, "href", "linus.gif");</pre>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2671
2672<p>Not really rocket science ...</p>
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]2673
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]2674<h3><a name="Traversing">Traversing the tree</a></h3>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2675
Daniel Veillard9cb5ff42001-01-29 08:22:21 +0000[diff] [blame]2676<p>Basically by <a href="html/libxml-tree.html">including "tree.h"</a> your
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]2677code has access to the internal structure of all the elements of the tree.
2678The names should be somewhat simple like <strong>parent</strong>,
Daniel Veillard306be992000-07-03 12:38:45 +0000[diff] [blame]2679<strong>children</strong>, <strong>next</strong>, <strong>prev</strong>,
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]2680<strong>properties</strong>, etc... For example, still with the previous
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]2681example:</p>
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]2682<pre><code>doc-&gt;children-&gt;children-&gt;children</code></pre>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2683
2684<p>points to the title element,</p>
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]2685<pre>doc-&gt;children-&gt;children-&gt;next-&gt;children-&gt;children</pre>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2686
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]2687<p>points to the text node containing the chapter title "The Linux
2688adventure".</p>
Daniel Veillard10c6a8f1998-10-28 01:00:12 +0000[diff] [blame]2689
Daniel Veillardb24054a1999-12-18 15:32:46 +0000[diff] [blame]2690<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]2691present before the document root, so <code>doc-&gt;children</code> may point
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]2692to an element which is not the document Root Element; a function
Daniel Veillard5cb5ab81999-12-21 15:35:29 +0000[diff] [blame]2693<code>xmlDocGetRootElement()</code> was added for this purpose.</p>
Daniel Veillardb24054a1999-12-18 15:32:46 +0000[diff] [blame]2694
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]2695<h3><a name="Modifying">Modifying the tree</a></h3>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2696
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]2697<p>Functions are provided for reading and writing the document content. Here
Daniel Veillard9cb5ff42001-01-29 08:22:21 +0000[diff] [blame]2698is an excerpt from the <a href="html/libxml-tree.html">tree API</a>:</p>
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]2699<dl>
Daniel Veillarddd6b3671999-09-23 22:19:22 +0000[diff] [blame]2700 <dt><code>xmlAttrPtr xmlSetProp(xmlNodePtr node, const xmlChar *name, const
2701 xmlChar *value);</code></dt>
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]2702 <dd><p>This sets (or changes) an attribute carried by an ELEMENT node.
2703 The value can be NULL.</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2704 </dd>
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]2705</dl>
2706<dl>
Daniel Veillarddd6b3671999-09-23 22:19:22 +0000[diff] [blame]2707 <dt><code>const xmlChar *xmlGetProp(xmlNodePtr node, const xmlChar
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2708 *name);</code></dt>
Daniel Veillardc92c3042000-09-29 02:42:04 +0000[diff] [blame]2709 <dd><p>This function returns a pointer to new copy of the property
2710 content. Note that the user must deallocate the result.</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2711 </dd>
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]2712</dl>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2713
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]2714<p>Two functions are provided for reading and writing the text associated
2715with elements:</p>
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]2716<dl>
Daniel Veillarddd6b3671999-09-23 22:19:22 +0000[diff] [blame]2717 <dt><code>xmlNodePtr xmlStringGetNodeList(xmlDocPtr doc, const xmlChar
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2718 *value);</code></dt>
Daniel Veillardec70e912001-02-26 20:10:45 +0000[diff] [blame]2719 <dd><p>This function takes an "external" string and converts it to one
2720 text node or possibly to a list of entity and text nodes. All
2721 non-predefined entity references like &amp;Gnome; will be stored
2722 internally as entity nodes, hence the result of the function may not be
2723 a single node.</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2724 </dd>
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]2725</dl>
2726<dl>
Daniel Veillarddd6b3671999-09-23 22:19:22 +0000[diff] [blame]2727 <dt><code>xmlChar *xmlNodeListGetString(xmlDocPtr doc, xmlNodePtr list, int
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2728 inLine);</code></dt>
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]2729 <dd><p>This function is the inverse of
2730 <code>xmlStringGetNodeList()</code>. It generates a new string
2731 containing the content of the text and entity nodes. Note the extra
2732 argument inLine. If this argument is set to 1, the function will expand
2733 entity references. For example, instead of returning the &amp;Gnome;
2734 XML encoding in the string, it will substitute it with its value (say,
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]2735 "GNU Network Object Model Environment").</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2736 </dd>
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]2737</dl>
Daniel Veillard10c6a8f1998-10-28 01:00:12 +0000[diff] [blame]2738
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]2739<h3><a name="Saving">Saving a tree</a></h3>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2740
2741<p>Basically 3 options are possible:</p>
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]2742<dl>
Daniel Veillarddd6b3671999-09-23 22:19:22 +0000[diff] [blame]2743 <dt><code>void xmlDocDumpMemory(xmlDocPtr cur, xmlChar**mem, int
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2744 *size);</code></dt>
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]2745 <dd><p>Returns a buffer into which the document has been saved.</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>
2748<dl>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2749 <dt><code>extern void xmlDocDump(FILE *f, xmlDocPtr doc);</code></dt>
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]2750 <dd><p>Dumps a document to an open file descriptor.</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2751 </dd>
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]2752</dl>
2753<dl>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2754 <dt><code>int xmlSaveFile(const char *filename, xmlDocPtr cur);</code></dt>
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]2755 <dd><p>Saves the document to a file. In this case, the compression
2756 interface is triggered if it has been turned on.</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2757 </dd>
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]2758</dl>
Daniel Veillard10c6a8f1998-10-28 01:00:12 +0000[diff] [blame]2759
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]2760<h3><a name="Compressio">Compression</a></h3>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2761
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]2762<p>The library transparently handles compression when doing file-based
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]2763accesses. The level of compression on saves can be turned on either globally
2764or individually for one file:</p>
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]2765<dl>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2766 <dt><code>int xmlGetDocCompressMode (xmlDocPtr doc);</code></dt>
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]2767 <dd><p>Gets the document compression ratio (0-9).</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2768 </dd>
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]2769</dl>
2770<dl>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2771 <dt><code>void xmlSetDocCompressMode (xmlDocPtr doc, int mode);</code></dt>
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]2772 <dd><p>Sets the document compression ratio.</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2773 </dd>
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]2774</dl>
2775<dl>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2776 <dt><code>int xmlGetCompressMode(void);</code></dt>
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]2777 <dd><p>Gets the default compression ratio.</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 xmlSetCompressMode(int mode);</code></dt>
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]2782 <dd><p>Sets the default 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
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]2786<h2><a name="Entities">Entities or no entities</a></h2>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]2787
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]2788<p>Entities in principle are similar to simple C macros. An entity defines an
2789abbreviation for a given string that you can reuse many times throughout the
2790content of your document. Entities are especially useful when a given string
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]2791may occur frequently within a document, or to confine the change needed to a
2792document to a restricted area in the internal subset of the document (at the
2793beginning). Example:</p>
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]2794<pre>1 &lt;?xml version="1.0"?&gt;
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]27952 &lt;!DOCTYPE EXAMPLE SYSTEM "example.dtd" [
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]27963 &lt;!ENTITY xml "Extensible Markup Language"&gt;
27974 ]&gt;
27985 &lt;EXAMPLE&gt;
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]27996 &amp;xml;
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]28007 &lt;/EXAMPLE&gt;</pre>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]2801
2802<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]2803its name with '&amp;' and following it by ';' without any spaces added. There
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]2804are 5 predefined entities in libxml allowing you to escape charaters with
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]2805predefined meaning in some parts of the xml document content:
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]2806<strong>&amp;lt;</strong> for the character '&lt;', <strong>&amp;gt;</strong>
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]2807for the character '&gt;', <strong>&amp;apos;</strong> for the character ''',
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]2808<strong>&amp;quot;</strong> for the character '"', and
2809<strong>&amp;amp;</strong> for the character '&amp;'.</p>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]2810
2811<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]2812substitute an entity's content so that you can see the replacement text in
2813your application. Or you may prefer to keep entity references as such in the
2814content to be able to save the document back without losing this usually
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]2815precious information (if the user went through the pain of explicitly
2816defining entities, he may have a a rather negative attitude if you blindly
2817susbtitute them as saving time). The <a
Daniel Veillard9cb5ff42001-01-29 08:22:21 +0000[diff] [blame]2818href="html/libxml-parser.html#XMLSUBSTITUTEENTITIESDEFAULT">xmlSubstituteEntitiesDefault()</a>
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]2819function allows you to check and change the behaviour, which is to not
2820substitute entities by default.</p>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]2821
2822<p>Here is the DOM tree built by libxml for the previous document in the
2823default case:</p>
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]2824<pre>/gnome/src/gnome-xml -&gt; ./xmllint --debug test/ent1
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]2825DOCUMENT
2826version=1.0
2827 ELEMENT EXAMPLE
2828 TEXT
2829 content=
2830 ENTITY_REF
2831 INTERNAL_GENERAL_ENTITY xml
2832 content=Extensible Markup Language
2833 TEXT
2834 content=</pre>
2835
2836<p>And here is the result when substituting entities:</p>
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]2837<pre>/gnome/src/gnome-xml -&gt; ./tester --debug --noent test/ent1
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]2838DOCUMENT
2839version=1.0
2840 ELEMENT EXAMPLE
2841 TEXT
2842 content= Extensible Markup Language</pre>
2843
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]2844<p>So, entities or no entities? Basically, it depends on your use case. I
2845suggest that you keep the non-substituting default behaviour and avoid using
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]2846entities in your XML document or data if you are not willing to handle the
2847entity references elements in the DOM tree.</p>
2848
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]2849<p>Note that at save time libxml enforces the conversion of the predefined
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]2850entities where necessary to prevent well-formedness problems, and will also
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]2851transparently replace those with chars (i.e. it will not generate entity
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]2852reference elements in the DOM tree or call the reference() SAX callback when
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]2853finding them in the input).</p>
2854
Daniel Veillard7b9c4b72000-08-25 16:26:50 +0000[diff] [blame]2855<p><span style="background-color: #FF0000">WARNING</span>: handling entities
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]2856on top of the libxml SAX interface is difficult!!! If you plan to use
Daniel Veillard7b9c4b72000-08-25 16:26:50 +0000[diff] [blame]2857non-predefined entities in your documents, then the learning cuvre to handle
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]2858then 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]2859strongly suggest you consider using the DOM interface instead and let libxml
Daniel Veillard8c6d6af2000-08-25 17:14:13 +0000[diff] [blame]2860deal with the complexity rather than trying to do it yourself.</p>
Daniel Veillard7b9c4b72000-08-25 16:26:50 +0000[diff] [blame]2861
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]2862<h2><a name="Namespaces">Namespaces</a></h2>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]2863
Daniel Veillardec303412000-03-24 13:41:54 +0000[diff] [blame]2864<p>The libxml library implements <a
2865href="http://www.w3.org/TR/REC-xml-names/">XML namespaces</a> support by
2866recognizing namespace contructs in the input, and does namespace lookup
2867automatically when building the DOM tree. A namespace declaration is
2868associated with an in-memory structure and all elements or attributes within
2869that namespace point to it. Hence testing the namespace is a simple and fast
2870equality operation at the user level.</p>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]2871
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]2872<p>I suggest that people using libxml use a namespace, and declare it in the
2873root element of their document as the default namespace. Then they don't need
2874to 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]2875refinement and merging of data from different sources. This doesn't increase
Daniel Veillardec70e912001-02-26 20:10:45 +0000[diff] [blame]2876the size of the XML output significantly, but significantly increases its
2877value in the long-term. Example:</p>
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]2878<pre>&lt;mydoc xmlns="http://mydoc.example.org/schemas/"&gt;
2879 &lt;elem1&gt;...&lt;/elem1&gt;
2880 &lt;elem2&gt;...&lt;/elem2&gt;
2881&lt;/mydoc&gt;</pre>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]2882
Daniel Veillardec70e912001-02-26 20:10:45 +0000[diff] [blame]2883<p>The namespace value has to be an absolute URL, but the URL doesn't have to
2884point to any existing resource on the Web. It will bind all the element and
2885atributes with that URL. I suggest to use an URL within a domain you control,
2886and that the URL should contain some kind of version information if possible.
2887For example, <code>"http://www.gnome.org/gnumeric/1.0/"</code> is a good
2888namespace scheme.</p>
Daniel Veillardec303412000-03-24 13:41:54 +0000[diff] [blame]2889
2890<p>Then when you load a file, make sure that a namespace carrying the
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]2891version-independent prefix is installed on the root element of your document,
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]2892and if the version information don't match something you know, warn the user
2893and 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]2894namespace checking on the prefix value. &lt;foo:text&gt; may be exactly the
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]2895same as &lt;bar:text&gt; in another document. What really matters is the URI
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]2896associated with the element or the attribute, not the prefix string (which is
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]2897just a shortcut for the full URI). In libxml, element and attributes have an
Daniel Veillardec303412000-03-24 13:41:54 +0000[diff] [blame]2898<code>ns</code> field pointing to an xmlNs structure detailing the namespace
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]2899prefix and its URI.</p>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]2900
2901<p>@@Interfaces@@</p>
2902
2903<p>@@Examples@@</p>
2904
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]2905<p>Usually people object to using namespaces together with validity checking.
2906I will try to make sure that using namespaces won't break validity checking,
2907so even if you plan to use or currently are using validation I strongly
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]2908suggest adding namespaces to your document. A default namespace scheme
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]2909<code>xmlns="http://...."</code> should not break validity even on less
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]2910flexible parsers. Using namespaces to mix and differentiate content coming
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]2911from multiple DTDs will certainly break current validation schemes. I will
2912try to provide ways to do this, but this may not be portable or
2913standardized.</p>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]2914
Daniel Veillardb8cfbd12001-10-25 10:53:28 +0000[diff] [blame]2915<h2><a name="Upgrading">Upgrading 1.x code</a></h2>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]2916
Daniel Veillardb8cfbd12001-10-25 10:53:28 +0000[diff] [blame]2917<p>Incompatible changes:</p>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]2918
Daniel Veillardb8cfbd12001-10-25 10:53:28 +0000[diff] [blame]2919<p>Version 2 of libxml is the first version introducing serious backward
2920incompatible changes. The main goals were:</p>
2921<ul>
2922 <li>a general cleanup. A number of mistakes inherited from the very early
2923 versions couldn't be changed due to compatibility constraints. Example
2924 the "childs" element in the nodes.</li>
2925 <li>Uniformization of the various nodes, at least for their header and link
2926 parts (doc, parent, children, prev, next), the goal is a simpler
2927 programming model and simplifying the task of the DOM implementors.</li>
2928 <li>better conformances to the XML specification, for example version 1.x
2929 had an heuristic to try to detect ignorable white spaces. As a result the
2930 SAX event generated were ignorableWhitespace() while the spec requires
2931 character() in that case. This also mean that a number of DOM node
2932 containing blank text may populate the DOM tree which were not present
2933 before.</li>
2934</ul>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]2935
Daniel Veillardb8cfbd12001-10-25 10:53:28 +0000[diff] [blame]2936<h3>How to fix libxml-1.x code:</h3>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]2937
Daniel Veillardb8cfbd12001-10-25 10:53:28 +0000[diff] [blame]2938<p>So client code of libxml designed to run with version 1.x may have to be
2939changed to compile against version 2.x of libxml. Here is a list of changes
2940that I have collected, they may not be sufficient, so in case you find other
2941change which are required, <a href="mailto:Daniel.Ïeillardw3.org">drop me a
2942mail</a>:</p>
2943<ol>
2944 <li>The package name have changed from libxml to libxml2, the library name
2945 is now -lxml2 . There is a new xml2-config script which should be used to
2946 select the right parameters libxml2</li>
2947 <li>Node <strong>childs</strong> field has been renamed
2948 <strong>children</strong> so s/childs/children/g should be applied
2949 (probablility of having "childs" anywere else is close to 0+</li>
2950 <li>The document don't have anymore a <strong>root</strong> element it has
2951 been replaced by <strong>children</strong> and usually you will get a
2952 list of element here. For example a Dtd element for the internal subset
2953 and it's declaration may be found in that list, as well as processing
2954 instructions or comments found before or after the document root element.
2955 Use <strong>xmlDocGetRootElement(doc)</strong> to get the root element of
2956 a document. Alternatively if you are sure to not reference Dtds nor have
2957 PIs or comments before or after the root element
2958 s/-&gt;root/-&gt;children/g will probably do it.</li>
2959 <li>The white space issue, this one is more complex, unless special case of
2960 validating parsing, the line breaks and spaces usually used for indenting
2961 and formatting the document content becomes significant. So they are
2962 reported by SAX and if your using the DOM tree, corresponding nodes are
2963 generated. Too approach can be taken:
2964 <ol>
2965 <li>lazy one, use the compatibility call
2966 <strong>xmlKeepBlanksDefault(0)</strong> but be aware that you are
2967 relying on a special (and possibly broken) set of heuristics of
2968 libxml to detect ignorable blanks. Don't complain if it breaks or
2969 make your application not 100% clean w.r.t. to it's input.</li>
2970 <li>the Right Way: change you code to accept possibly unsignificant
2971 blanks characters, or have your tree populated with weird blank text
2972 nodes. You can spot them using the comodity function
2973 <strong>xmlIsBlankNode(node)</strong> returning 1 for such blank
2974 nodes.</li>
2975 </ol>
2976 <p>Note also that with the new default the output functions don't add any
2977 extra indentation when saving a tree in order to be able to round trip
2978 (read and save) without inflating the document with extra formatting
2979 chars.</p>
2980 </li>
2981 <li>The include path has changed to $prefix/libxml/ and the includes
2982 themselves uses this new prefix in includes instructions... If you are
2983 using (as expected) the
2984 <pre>xml2-config --cflags</pre>
2985 <p>output to generate you compile commands this will probably work out of
2986 the box</p>
2987 </li>
2988 <li>xmlDetectCharEncoding takes an extra argument indicating the lenght in
2989 byte of the head of the document available for character detection.</li>
2990</ol>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]2991
Daniel Veillardb8cfbd12001-10-25 10:53:28 +0000[diff] [blame]2992<h3>Ensuring both libxml-1.x and libxml-2.x compatibility</h3>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]2993
Daniel Veillardb8cfbd12001-10-25 10:53:28 +0000[diff] [blame]2994<p>Two new version of libxml (1.8.11) and libxml2 (2.3.4) have been released
2995to allow smoth upgrade of existing libxml v1code while retaining
2996compatibility. They offers the following:</p>
2997<ol>
2998 <li>similar include naming, one should use
2999 <strong>#include&lt;libxml/...&gt;</strong> in both cases.</li>
3000 <li>similar identifiers defined via macros for the child and root fields:
3001 respectively <strong>xmlChildrenNode</strong> and
3002 <strong>xmlRootNode</strong></li>
3003 <li>a new macro <strong>LIBXML_TEST_VERSION</strong> which should be
3004 inserted once in the client code</li>
3005</ol>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]3006
Daniel Veillardb8cfbd12001-10-25 10:53:28 +0000[diff] [blame]3007<p>So the roadmap to upgrade your existing libxml applications is the
3008following:</p>
3009<ol>
3010 <li>install the libxml-1.8.8 (and libxml-devel-1.8.8) packages</li>
3011 <li>find all occurences where the xmlDoc <strong>root</strong> field is
3012 used and change it to <strong>xmlRootNode</strong></li>
3013 <li>similary find all occurences where the xmlNode <strong>childs</strong>
3014 field is used and change it to <strong>xmlChildrenNode</strong></li>
3015 <li>add a <strong>LIBXML_TEST_VERSION</strong> macro somewhere in your
3016 <strong>main()</strong> or in the library init entry point</li>
3017 <li>Recompile, check compatibility, it should still work</li>
3018 <li>Change your configure script to look first for xml2-config and fallback
3019 using xml-config . Use the --cflags and --libs ouptut of the command as
3020 the Include and Linking parameters needed to use libxml.</li>
3021 <li>install libxml2-2.3.x and libxml2-devel-2.3.x (libxml-1.8.y and
3022 libxml-devel-1.8.y can be kept simultaneously)</li>
3023 <li>remove your config.cache, relaunch your configuration mechanism, and
3024 recompile, if steps 2 and 3 were done right it should compile as-is</li>
3025 <li>Test that your application is still running correctly, if not this may
3026 be due to extra empty nodes due to formating spaces being kept in libxml2
3027 contrary to libxml1, in that case insert xmlKeepBlanksDefault(1) in your
3028 code before calling the parser (next to
3029 <strong>LIBXML_TEST_VERSION</strong> is a fine place).</li>
3030</ol>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]3031
Daniel Veillardb8cfbd12001-10-25 10:53:28 +0000[diff] [blame]3032<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]3033
Daniel Veillardb8cfbd12001-10-25 10:53:28 +0000[diff] [blame]3034<p>Let me put some emphasis on the fact that there is far more changes from
3035libxml 1.x to 2.x than the ones you may have to patch for. The overall code
3036has been considerably cleaned up and the conformance to the XML specification
3037has been drastically improved too. Don't take those changes as an excuse to
3038not upgrade, it may cost a lot on the long term ...</p>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]3039
Daniel Veillard52dcab32001-10-30 12:51:17 +0000[diff] [blame]3040<h2><a name="Thread">Thread safety</a></h2>
3041
3042<p>Starting with 2.4.7, libxml makes provisions to ensure that concurent
3043threads can safely work in parallel parsing different documents. There is
3044however a couple of things to do to ensure it:</p>
3045<ul>
3046 <li>configure the library accordingly using the --with-threads options</li>
3047 <li>call xmlInitParser() in the "main" thread before using any of the
3048 libxml API (except possibly selecting a different memory allocator)</li>
3049</ul>
3050
3051<p>Note that the thread safety cannot be ensured for multiple threads sharing
3052the same document, the locking must be done at the application level, libxml
3053exports a basic mutex and reentrant mutexes API in &lt;libxml/threads.h&gt;.
3054The parts of the library checked for thread safety are:</p>
3055<ul>
3056 <li>concurrent loading</li>
3057 <li>file access resolution</li>
3058 <li>catalog access</li>
3059 <li>catalog building</li>
3060 <li>entities lookup/accesses</li>
3061 <li>validation</li>
3062 <li>global variables per-thread override</li>
3063 <li>memory handling</li>
3064</ul>
3065
3066<p>XPath is supposed to be thread safe now, but this wasn't tested
3067seriously.</p>
3068
Daniel Veillard35008381999-10-25 13:15:52 +0000[diff] [blame]3069<h2><a name="DOM"></a><a name="Principles">DOM Principles</a></h2>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]3070
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]3071<p><a href="http://www.w3.org/DOM/">DOM</a> stands for the <em>Document
3072Object Model</em>; this is an API for accessing XML or HTML structured
3073documents. Native support for DOM in Gnome is on the way (module gnome-dom),
3074and will be based on gnome-xml. This will be a far cleaner interface to
3075manipulate XML files within Gnome since it won't expose the internal
3076structure.</p>
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]3077
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]3078<p>The current DOM implementation on top of libxml is the <a
Daniel Veillarda47fb3d2001-03-25 17:23:49 +0000[diff] [blame]3079href="http://cvs.gnome.org/lxr/source/gdome2/">gdome2 Gnome module</a>, this
3080is a full DOM interface, thanks to Paolo Casarini, check the <a
3081href="http://www.cs.unibo.it/~casarini/gdome2/">Gdome2 homepage</a> for more
3082informations.</p>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]3083
Daniel Veillard35008381999-10-25 13:15:52 +0000[diff] [blame]3084<h2><a name="Example"></a><a name="real">A real example</a></h2>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]3085
3086<p>Here is a real size example, where the actual content of the application
3087data 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]3088a proposal to keep a database of jobs related to Gnome, with an XML based
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]3089storage structure. Here is an <a href="gjobs.xml">XML encoded jobs
3090base</a>:</p>
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]3091<pre>&lt;?xml version="1.0"?&gt;
3092&lt;gjob:Helping xmlns:gjob="http://www.gnome.org/some-location"&gt;
3093 &lt;gjob:Jobs&gt;
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]3094
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]3095 &lt;gjob:Job&gt;
3096 &lt;gjob:Project ID="3"/&gt;
3097 &lt;gjob:Application&gt;GBackup&lt;/gjob:Application&gt;
3098 &lt;gjob:Category&gt;Development&lt;/gjob:Category&gt;
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]3099
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]3100 &lt;gjob:Update&gt;
3101 &lt;gjob:Status&gt;Open&lt;/gjob:Status&gt;
3102 &lt;gjob:Modified&gt;Mon, 07 Jun 1999 20:27:45 -0400 MET DST&lt;/gjob:Modified&gt;
3103 &lt;gjob:Salary&gt;USD 0.00&lt;/gjob:Salary&gt;
3104 &lt;/gjob:Update&gt;
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]3105
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]3106 &lt;gjob:Developers&gt;
3107 &lt;gjob:Developer&gt;
3108 &lt;/gjob:Developer&gt;
3109 &lt;/gjob:Developers&gt;
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]3110
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]3111 &lt;gjob:Contact&gt;
3112 &lt;gjob:Person&gt;Nathan Clemons&lt;/gjob:Person&gt;
3113 &lt;gjob:Email&gt;nathan@windsofstorm.net&lt;/gjob:Email&gt;
3114 &lt;gjob:Company&gt;
3115 &lt;/gjob:Company&gt;
3116 &lt;gjob:Organisation&gt;
3117 &lt;/gjob:Organisation&gt;
3118 &lt;gjob:Webpage&gt;
3119 &lt;/gjob:Webpage&gt;
3120 &lt;gjob:Snailmail&gt;
3121 &lt;/gjob:Snailmail&gt;
3122 &lt;gjob:Phone&gt;
3123 &lt;/gjob:Phone&gt;
3124 &lt;/gjob:Contact&gt;
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]3125
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]3126 &lt;gjob:Requirements&gt;
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]3127 The program should be released as free software, under the GPL.
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]3128 &lt;/gjob:Requirements&gt;
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]3129
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]3130 &lt;gjob:Skills&gt;
3131 &lt;/gjob:Skills&gt;
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]3132
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]3133 &lt;gjob:Details&gt;
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]3134 A GNOME based system that will allow a superuser to configure
3135 compressed and uncompressed files and/or file systems to be backed
3136 up with a supported media in the system. This should be able to
3137 perform via find commands generating a list of files that are passed
3138 to tar, dd, cpio, cp, gzip, etc., to be directed to the tape machine
3139 or via operations performed on the filesystem itself. Email
3140 notification and GUI status display very important.
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]3141 &lt;/gjob:Details&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:Job&gt;
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]3144
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]3145 &lt;/gjob:Jobs&gt;
3146&lt;/gjob:Helping&gt;</pre>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]3147
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]3148<p>While loading the XML file into an internal DOM tree is a matter of
3149calling only a couple of functions, browsing the tree to gather the ata and
3150generate the internal structures is harder, and more error prone.</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]3151
3152<p>The suggested principle is to be tolerant with respect to the input
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]3153structure. For example, the ordering of the attributes is not significant,
3154the 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]3155depend on the order of the children of a given node, unless it really makes
3156things harder. Here is some code to parse the information for a person:</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]3157<pre>/*
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]3158 * A person record
3159 */
3160typedef struct person {
3161 char *name;
3162 char *email;
3163 char *company;
3164 char *organisation;
3165 char *smail;
3166 char *webPage;
3167 char *phone;
3168} person, *personPtr;
3169
3170/*
3171 * And the code needed to parse it
3172 */
3173personPtr parsePerson(xmlDocPtr doc, xmlNsPtr ns, xmlNodePtr cur) {
3174 personPtr ret = NULL;
3175
3176DEBUG("parsePerson\n");
3177 /*
3178 * allocate the struct
3179 */
3180 ret = (personPtr) malloc(sizeof(person));
3181 if (ret == NULL) {
3182 fprintf(stderr,"out of memory\n");
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]3183 return(NULL);
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]3184 }
3185 memset(ret, 0, sizeof(person));
3186
3187 /* We don't care what the top level element name is */
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]3188 cur = cur-&gt;xmlChildrenNode;
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]3189 while (cur != NULL) {
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]3190 if ((!strcmp(cur-&gt;name, "Person")) &amp;&amp; (cur-&gt;ns == ns))
3191 ret-&gt;name = xmlNodeListGetString(doc, cur-&gt;xmlChildrenNode, 1);
3192 if ((!strcmp(cur-&gt;name, "Email")) &amp;&amp; (cur-&gt;ns == ns))
3193 ret-&gt;email = xmlNodeListGetString(doc, cur-&gt;xmlChildrenNode, 1);
3194 cur = cur-&gt;next;
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]3195 }
3196
3197 return(ret);
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]3198}</pre>
3199
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]3200<p>Here are a couple of things to notice:</p>
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]3201<ul>
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]3202 <li>Usually a recursive parsing style is the more convenient one: XML data
3203 is by nature subject to repetitive constructs and usually exibits highly
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]3204 stuctured patterns.</li>
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]3205 <li>The two arguments of type <em>xmlDocPtr</em> and <em>xmlNsPtr</em>,
3206 i.e. the pointer to the global XML document and the namespace reserved to
3207 the application. Document wide information are needed for example to
3208 decode entities and it's a good coding practice to define a namespace for
3209 your application set of data and test that the element and attributes
3210 you're analyzing actually pertains to your application space. This is
3211 done by a simple equality test (cur-&gt;ns == ns).</li>
Daniel Veillardec70e912001-02-26 20:10:45 +0000[diff] [blame]3212 <li>To retrieve text and attributes value, you can use the function
3213 <em>xmlNodeListGetString</em> to gather all the text and entity reference
3214 nodes generated by the DOM output and produce an single text string.</li>
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]3215</ul>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]3216
3217<p>Here is another piece of code used to parse another level of the
3218structure:</p>
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]3219<pre>#include &lt;libxml/tree.h&gt;
Daniel Veillard361d8452000-04-03 19:48:13 +0000[diff] [blame]3220/*
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]3221 * a Description for a Job
3222 */
3223typedef struct job {
3224 char *projectID;
3225 char *application;
3226 char *category;
3227 personPtr contact;
3228 int nbDevelopers;
3229 personPtr developers[100]; /* using dynamic alloc is left as an exercise */
3230} job, *jobPtr;
3231
3232/*
3233 * And the code needed to parse it
3234 */
3235jobPtr parseJob(xmlDocPtr doc, xmlNsPtr ns, xmlNodePtr cur) {
3236 jobPtr ret = NULL;
3237
3238DEBUG("parseJob\n");
3239 /*
3240 * allocate the struct
3241 */
3242 ret = (jobPtr) malloc(sizeof(job));
3243 if (ret == NULL) {
3244 fprintf(stderr,"out of memory\n");
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]3245 return(NULL);
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]3246 }
3247 memset(ret, 0, sizeof(job));
3248
3249 /* We don't care what the top level element name is */
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]3250 cur = cur-&gt;xmlChildrenNode;
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]3251 while (cur != NULL) {
3252
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]3253 if ((!strcmp(cur-&gt;name, "Project")) &amp;&amp; (cur-&gt;ns == ns)) {
3254 ret-&gt;projectID = xmlGetProp(cur, "ID");
3255 if (ret-&gt;projectID == NULL) {
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]3256 fprintf(stderr, "Project has no ID\n");
3257 }
3258 }
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]3259 if ((!strcmp(cur-&gt;name, "Application")) &amp;&amp; (cur-&gt;ns == ns))
3260 ret-&gt;application = xmlNodeListGetString(doc, cur-&gt;xmlChildrenNode, 1);
3261 if ((!strcmp(cur-&gt;name, "Category")) &amp;&amp; (cur-&gt;ns == ns))
3262 ret-&gt;category = xmlNodeListGetString(doc, cur-&gt;xmlChildrenNode, 1);
3263 if ((!strcmp(cur-&gt;name, "Contact")) &amp;&amp; (cur-&gt;ns == ns))
3264 ret-&gt;contact = parsePerson(doc, ns, cur);
3265 cur = cur-&gt;next;
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]3266 }
3267
3268 return(ret);
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]3269}</pre>
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]3270
Daniel Veillardec70e912001-02-26 20:10:45 +0000[diff] [blame]3271<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]3272boring. Ultimately, it could be possble to write stubbers taking either C
3273data structure definitions, a set of XML examples or an XML DTD and produce
3274the code needed to import and export the content between C data and XML
3275storage. This is left as an exercise to the reader :-)</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]3276
Daniel Veillard6f0adb52000-07-03 11:41:26 +0000[diff] [blame]3277<p>Feel free to use <a href="example/gjobread.c">the code for the full C
3278parsing example</a> as a template, it is also available with Makefile in the
3279Gnome CVS base under gnome-xml/example</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]3280
Daniel Veillardc310d562000-06-23 18:32:15 +0000[diff] [blame]3281<h2><a name="Contributi">Contributions</a></h2>
3282<ul>
Daniel Veillardb8cfbd12001-10-25 10:53:28 +0000[diff] [blame]3283 <li>Bjorn Reese, William Brack and Thomas Broyer have provided a number of
3284 patches, Gary Pennington worked on the validation API, threading support
3285 and Solaris port.</li>
3286 <li>John Fleck helps maintaining the documentation and man pages.</li>
Daniel Veillardc6271d22001-10-27 07:50:58 +0000[diff] [blame]3287 <li><a href="mailto:ari@lusis.org">Ari Johnson</a>
Daniel Veillard51095312001-10-28 18:51:57 +0000[diff] [blame]3288 provides a C++ wrapper for libxml:<br>
Daniel Veillardc6271d22001-10-27 07:50:58 +0000[diff] [blame]3289 Website: <a
3290 href="http://lusis.org/~ari/xml++/">http://lusis.org/~ari/xml++/</a><br>
3291 Download: <a
Daniel Veillard51095312001-10-28 18:51:57 +0000[diff] [blame]3292 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]3293 <li><a href="mailto:izlatkovic@daenet.de">Igor Zlatkovic</a>
3294 is now the maintainer of the Windows port, <a
Daniel Veillard95189532001-07-26 18:30:26 +0000[diff] [blame]3295 href="http://www.fh-frankfurt.de/~igor/projects/libxml/index.html">he
3296 provides binaries</a></li>
Daniel Veillardc9484202001-10-24 12:35:52 +0000[diff] [blame]3297 <li><a href="mailto:Gary.Pennington@sun.com">Gary Pennington</a>
3298 provides <a href="http://pages.eidosnet.co.uk/~garypen/libxml/">Solaris
Daniel Veillard0a702dc2001-10-19 14:50:57 +0000[diff] [blame]3299 binaries</a></li>
Daniel Veillarde356c282001-03-10 12:32:04 +0000[diff] [blame]3300 <li><a
3301 href="http://mail.gnome.org/archives/xml/2001-March/msg00014.html">Matt
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]3302 Sergeant</a>
3303 developped <a href="http://axkit.org/download/">XML::LibXSLT</a>, a perl
3304 wrapper for libxml2/libxslt as part of the <a
3305 href="http://axkit.com/">AxKit XML application server</a></li>
3306 <li><a href="mailto:fnatter@gmx.net">Felix Natter</a>
3307 and <a href="mailto:geertk@ai.rug.nl">Geert Kloosterman</a> provide <a
Daniel Veillardca989762001-06-23 17:39:29 +0000[diff] [blame]3308 href="libxml-doc.el">an emacs module</a> to lookup libxml(2) functions
Daniel Veillard3f6f7f62000-06-30 17:58:25 +0000[diff] [blame]3309 documentation</li>
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]3310 <li><a href="mailto:sherwin@nlm.nih.gov">Ziying Sherwin</a>
3311 provided <a href="http://xmlsoft.org/messages/0488.html">man
3312 pages</a></li>
Daniel Veillard5168dbf2001-07-07 00:18:23 +0000[diff] [blame]3313 <li>there is a module for <a
3314 href="http://acs-misc.sourceforge.net/nsxml.html">libxml/libxslt support
3315 in OpenNSD/AOLServer</a></li>
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]3316 <li><a href="mailto:dkuhlman@cutter.rexx.com">Dave Kuhlman</a>
3317 provides libxml/libxslt <a href="http://www.rexx.com/~dkuhlman">wrappers
3318 for Python</a></li>
Daniel Veillardc310d562000-06-23 18:32:15 +0000[diff] [blame]3319</ul>
3320
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]3321<p></p>
Daniel Veillardccb09631998-10-27 06:21:04 +0000[diff] [blame]3322</body>
3323</html>