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Daniel Veillard09ab7e12001-07-10 15:49:44 +0000[diff] [blame]1<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"
2 "http://www.w3.org/TR/html4/loose.dtd">
Daniel Veillardccb09631998-10-27 06:21:04 +0000[diff] [blame]3<html>
4<head>
Daniel Veillardec78c0f2000-08-25 10:25:23 +0000[diff] [blame]5 <title>The XML C library for Gnome</title>
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]6 <meta name="GENERATOR" content="amaya V5.0">
Daniel Veillardb24054a1999-12-18 15:32:46 +0000[diff] [blame]7 <meta http-equiv="Content-Type" content="text/html">
Daniel Veillardccb09631998-10-27 06:21:04 +0000[diff] [blame]8</head>
Daniel Veillardccb09631998-10-27 06:21:04 +0000[diff] [blame]9
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]10<body bgcolor="#ffffff">
Daniel Veillardec78c0f2000-08-25 10:25:23 +0000[diff] [blame]11<h1 align="center">The XML C library for Gnome</h1>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]12
Daniel 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
Daniel Veillard845cce42002-01-09 11:51:37 +0000[diff] [blame^]73<p>Libxml2 is known to be very portable, should build and work without
74serious troubles on a variety of systems (Linux, Unix, Windows, CygWin,
75MacOs, MacOsX, RISC Os, OS/2, VMS, QNX, MVS, ...)</p>
Daniel Veillard9c466822001-10-25 12:03:39 +0000[diff] [blame]76
Daniel Veillard96984452000-08-31 13:50:12 +0000[diff] [blame]77<p>Separate documents:</p>
78<ul>
Daniel Veillardc6271d22001-10-27 07:50:58 +0000[diff] [blame]79 <li><a href="http://xmlsoft.org/XSLT/">the libxslt page</a>
80 providing an implementation of XSLT 1.0 and extensions on top of
81 libxml2</li>
82 <li><a href="http://www.cs.unibo.it/~casarini/gdome2/">the gdome2 page</a>
Daniel Veillard51095312001-10-28 18:51:57 +0000[diff] [blame]83 : a standard DOM2 implementation based on libxml2</li>
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]84</ul>
85
86<h2><a name="Introducti">Introduction</a></h2>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]87
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]88<p>This document describes libxml, the <a
Daniel Veillardec78c0f2000-08-25 10:25:23 +0000[diff] [blame]89href="http://www.w3.org/XML/">XML</a> C library developped for the <a
90href="http://www.gnome.org/">Gnome</a> project. <a
91href="http://www.w3.org/XML/">XML is a standard</a> for building tag-based
92structured documents/data.</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]93
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]94<p>Here are some key points about libxml:</p>
95<ul>
Daniel Veillard189446d2000-10-13 10:23:06 +0000[diff] [blame]96 <li>Libxml exports Push and Pull type parser interfaces for both XML and
97 HTML.</li>
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]98 <li>Libxml can do DTD validation at parse time, using a parsed document
99 instance, or with an arbitrary DTD.</li>
100 <li>Libxml now includes nearly complete <a
Daniel Veillard8c2ecaf2001-07-10 17:53:07 +0000[diff] [blame]101 href="http://www.w3.org/TR/xpath">XPath</a>, <a
102 href="http://www.w3.org/TR/xptr">XPointer</a> and <a
103 href="http://www.w3.org/TR/xinclude">XInclude</a> implementations.</li>
Daniel Veillardec78c0f2000-08-25 10:25:23 +0000[diff] [blame]104 <li>It is written in plain C, making as few assumptions as possible, and
Daniel Veillard189446d2000-10-13 10:23:06 +0000[diff] [blame]105 sticking closely to ANSI C/POSIX for easy embedding. Works on
Daniel Veillardab8500d2000-10-15 21:06:19 +0000[diff] [blame]106 Linux/Unix/Windows, ported to a number of other platforms.</li>
Daniel Veillardec70e912001-02-26 20:10:45 +0000[diff] [blame]107 <li>Basic support for HTTP and FTP client allowing aplications to fetch
108 remote resources</li>
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]109 <li>The design is modular, most of the extensions can be compiled out.</li>
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]110 <li>The internal document repesentation is as close as possible to the <a
111 href="http://www.w3.org/DOM/">DOM</a> interfaces.</li>
112 <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]113 like interface</a>; the interface is designed to be compatible with <a
114 href="http://www.jclark.com/xml/expat.html">Expat</a>.</li>
Daniel Veillardec303412000-03-24 13:41:54 +0000[diff] [blame]115 <li>This library is released both under the <a
116 href="http://www.w3.org/Consortium/Legal/copyright-software-19980720.html">W3C
Daniel Veillard189446d2000-10-13 10:23:06 +0000[diff] [blame]117 IPR</a> and the <a href="http://www.gnu.org/copyleft/lesser.html">GNU
118 LGPL</a>. Use either at your convenience, basically this should make
119 everybody happy, if not, drop me a mail.</li>
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]120</ul>
Daniel Veillardccb09631998-10-27 06:21:04 +0000[diff] [blame]121
Daniel Veillarde0c1d722001-03-21 10:28:36 +0000[diff] [blame]122<p>Warning: unless you are forced to because your application links with a
123Gnome library requiring it, <strong><span
124style="background-color: #FF0000">Do Not Use libxml1</span></strong>, use
125libxml2</p>
126
Daniel Veillardb8cfbd12001-10-25 10:53:28 +0000[diff] [blame]127<h2><a name="FAQ">FAQ</a></h2>
128
129<p>Table of Content:</p>
130<ul>
131 <li><a href="FAQ.html#Licence">Licence(s)</a></li>
132 <li><a href="FAQ.html#Installati">Installation</a></li>
133 <li><a href="FAQ.html#Compilatio">Compilation</a></li>
134 <li><a href="FAQ.html#Developer">Developer corner</a></li>
135</ul>
136
137<h3><a name="Licence">Licence</a>(s)</h3>
138<ol>
139 <li><em>Licensing Terms for libxml</em>
140 <p>libxml is released under 2 (compatible) licences:</p>
141 <ul>
142 <li>the <a href="http://www.gnu.org/copyleft/lgpl.html">LGPL</a>: GNU
143 Library General Public License</li>
144 <li>the <a
145 href="http://www.w3.org/Consortium/Legal/copyright-software-19980720.html">W3C
146 IPR</a>: very similar to the XWindow licence</li>
147 </ul>
148 </li>
149 <li><em>Can I embed libxml in a proprietary application ?</em>
150 <p>Yes. The W3C IPR allows you to also keep proprietary the changes you
151 made to libxml, but it would be graceful to provide back bugfixes and
152 improvements as patches for possible incorporation in the main
153 development tree</p>
154 </li>
155</ol>
156
157<h3><a name="Installati">Installation</a></h3>
158<ol>
159 <li>Unless you are forced to because your application links with a Gnome
160 library requiring it, <strong><span style="background-color: #FF0000">Do
161 Not Use libxml1</span></strong>, use libxml2</li>
162 <li><em>Where can I get libxml</em>
163 ?
164 <p>The original distribution comes from <a
165 href="ftp://rpmfind.net/pub/libxml/">rpmfind.net</a> or <a
166 href="ftp://ftp.gnome.org/pub/GNOME/stable/sources/libxml/">gnome.org</a></p>
167 <p>Most linux and Bsd distribution includes libxml, this is probably the
168 safer way for end-users</p>
169 <p>David Doolin provides precompiled Windows versions at <a
170 href="http://www.ce.berkeley.edu/~doolin/code/libxmlwin32/ ">http://www.ce.berkeley.edu/~doolin/code/libxmlwin32/</a></p>
171 </li>
172 <li><em>I see libxml and libxml2 releases, which one should I install ?</em>
173 <ul>
174 <li>If you are not concerned by any existing backward compatibility
175 with existing application, install libxml2 only</li>
176 <li>If you are not doing development, you can safely install both.
177 usually the packages <a
178 href="http://rpmfind.net/linux/RPM/libxml.html">libxml</a> and <a
179 href="http://rpmfind.net/linux/RPM/libxml2.html">libxml2</a> are
180 compatible (this is not the case for development packages)</li>
181 <li>If you are a developer and your system provides separate packaging
182 for shared libraries and the development components, it is possible
183 to install libxml and libxml2, and also <a
184 href="http://rpmfind.net/linux/RPM/libxml-devel.html">libxml-devel</a>
185 and <a
186 href="http://rpmfind.net/linux/RPM/libxml2-devel.html">libxml2-devel</a>
187 too for libxml2 &gt;= 2.3.0</li>
188 <li>If you are developing a new application, please develop against
189 libxml2(-devel)</li>
190 </ul>
191 </li>
192 <li><em>I can't install the libxml package it conflicts with libxml0</em>
193 <p>You probably have an old libxml0 package used to provide the shared
194 library for libxml.so.0, you can probably safely remove it. Anyway the
195 libxml packages provided on <a
196 href="ftp://rpmfind.net/pub/libxml/">rpmfind.net</a> provides
197 libxml.so.0</p>
198 </li>
199 <li><em>I can't install the libxml(2) RPM package due to failed
200 dependancies</em>
201 <p>The most generic solution is to refetch the latest src.rpm , and
202 rebuild it locally with</p>
203 <p><code>rpm --rebuild libxml(2)-xxx.src.rpm</code></p>
204 <p>if everything goes well it will generate two binary rpm (one providing
205 the shared libs and xmllint, and the other one, the -devel package
206 providing includes, static libraries and scripts needed to build
207 applications with libxml(2)) that you can install locally.</p>
208 </li>
209</ol>
210
211<h3><a name="Compilatio">Compilation</a></h3>
212<ol>
213 <li><em>What is the process to compile libxml ?</em>
214 <p>As most UNIX libraries libxml follows the "standard":</p>
215 <p><code>gunzip -c xxx.tar.gz | tar xvf -</code></p>
216 <p><code>cd libxml-xxxx</code></p>
217 <p><code>./configure --help</code></p>
218 <p>to see the options, then the compilation/installation proper</p>
219 <p><code>./configure [possible options]</code></p>
220 <p><code>make</code></p>
221 <p><code>make install</code></p>
222 <p>At that point you may have to rerun ldconfig or similar utility to
223 update your list of installed shared libs.</p>
224 </li>
225 <li><em>What other libraries are needed to compile/install libxml ?</em>
226 <p>Libxml does not requires any other library, the normal C ANSI API
227 should be sufficient (please report any violation to this rule you may
228 find).</p>
229 <p>However if found at configuration time libxml will detect and use the
230 following libs:</p>
231 <ul>
232 <li><a href="http://www.info-zip.org/pub/infozip/zlib/">libz</a>
233 : a highly portable and available widely compression library</li>
234 <li>iconv: a powerful character encoding conversion library. It's
235 included by default on recent glibc libraries, so it doesn't need to
236 be installed specifically on linux. It seems it's now <a
237 href="http://www.opennc.org/onlinepubs/7908799/xsh/iconv.html">part
238 of the official UNIX</a> specification. Here is one <a
239 href="http://clisp.cons.org/~haible/packages-libiconv.html">implementation
240 of the library</a> which source can be found <a
241 href="ftp://ftp.ilog.fr/pub/Users/haible/gnu/">here</a>.</li>
242 </ul>
243 </li>
Daniel Veillardb8cfbd12001-10-25 10:53:28 +0000[diff] [blame]244 <li><em>make check fails on some platforms</em>
245 <p>Sometime the regression tests results don't completely match the value
246 produced by the parser, and the makefile uses diff to print the delta. On
247 some platforms the diff return breaks the compilation process, if the
248 diff is small this is probably not a serious problem</p>
249 </li>
250 <li><em>I use the CVS version and there is no configure script</em>
251 <p>The configure (and other Makefiles) are generated. Use the autogen.sh
252 script to regenerate the configure and Makefiles, like:</p>
253 <p><code>./autogen.sh --prefix=/usr --disable-shared</code></p>
254 </li>
255 <li><em>I have troubles when running make tests with gcc-3.0</em>
256 <p>It seems the initial release of gcc-3.0 has a problem with the
257 optimizer which miscompiles the URI module. Please use another
258 compiler</p>
259 </li>
260</ol>
261
262<h3><a name="Developer">Developer</a> corner</h3>
263<ol>
264 <li><em>xmlDocDump() generates output on one line</em>
265 <p>libxml will not <strong>invent</strong> spaces in the content of a
266 document since <strong>all spaces in the content of a document are
267 significant</strong>. If you build a tree from the API and want
268 indentation:</p>
269 <ol>
270 <li>the correct way is to generate those yourself too</li>
271 <li>the dangerous way is to ask libxml to add those blanks to your
272 content <strong>modifying the content of your document in the
273 process</strong>. The result may not be what you expect. There is
274 <strong>NO</strong> way to guarantee that such a modification won't
275 impact other part of the content of your document. See <a
276 href="http://xmlsoft.org/html/libxml-parser.html#XMLKEEPBLANKSDEFAULT">xmlKeepBlanksDefault
277 ()</a> and <a
278 href="http://xmlsoft.org/html/libxml-tree.html#XMLSAVEFORMATFILE">xmlSaveFormatFile
279 ()</a></li>
280 </ol>
281 </li>
282 <li>Extra nodes in the document:
283 <p><em>For a XML file as below:</em></p>
284 <pre>&lt;?xml version="1.0"?&gt;
285&lt;PLAN xmlns="http://www.argus.ca/autotest/1.0/"&gt;
286&lt;NODE CommFlag="0"/&gt;
287&lt;NODE CommFlag="1"/&gt;
288&lt;/PLAN&gt;</pre>
289 <p><em>after parsing it with the function
290 pxmlDoc=xmlParseFile(...);</em></p>
291 <p><em>I want to the get the content of the first node (node with the
292 CommFlag="0")</em></p>
293 <p><em>so I did it as following;</em></p>
294 <pre>xmlNodePtr pode;
295pnode=pxmlDoc-&gt;children-&gt;children;</pre>
296 <p><em>but it does not work. If I change it to</em></p>
297 <pre>pnode=pxmlDoc-&gt;children-&gt;children-&gt;next;</pre>
298 <p><em>then it works. Can someone explain it to me.</em></p>
299 <p></p>
300 <p>In XML all characters in the content of the document are significant
301 <strong>including blanks and formatting line breaks</strong>.</p>
302 <p>The extra nodes you are wondering about are just that, text nodes with
303 the formatting spaces wich are part of the document but that people tend
304 to forget. There is a function <a
305 href="http://xmlsoft.org/html/libxml-parser.html">xmlKeepBlanksDefault
306 ()</a> to remove those at parse time, but that's an heuristic, and its
307 use should be limited to case where you are sure there is no
308 mixed-content in the document.</p>
309 </li>
310 <li><em>I get compilation errors of existing code like when accessing
311 <strong>root</strong> or <strong>childs fields</strong> of nodes</em>
312 <p>You are compiling code developed for libxml version 1 and using a
313 libxml2 development environment. Either switch back to libxml v1 devel or
314 even better fix the code to compile with libxml2 (or both) by <a
315 href="upgrade.html">following the instructions</a>.</p>
316 </li>
317 <li><em>I get compilation errors about non existing
318 <strong>xmlRootNode</strong> or <strong>xmlChildrenNode</strong>
319 fields</em>
320 <p>The source code you are using has been <a
321 href="upgrade.html">upgraded</a> to be able to compile with both libxml
322 and libxml2, but you need to install a more recent version:
323 libxml(-devel) &gt;= 1.8.8 or libxml2(-devel) &gt;= 2.1.0</p>
324 </li>
325 <li><em>XPath implementation looks seriously broken</em>
326 <p>XPath implementation prior to 2.3.0 was really incomplete, upgrade to
327 a recent version, the implementation and debug of libxslt generated fixes
328 for most obvious problems.</p>
329 </li>
330 <li><em>The example provided in the web page does not compile</em>
331 <p>It's hard to maintain the documentation in sync with the code
332 &lt;grin/&gt; ...</p>
333 <p>Check the previous points 1/ and 2/ raised before, and send
334 patches.</p>
335 </li>
336 <li><em>Where can I get more examples and informations than in the web
337 page</em>
338 <p>Ideally a libxml book would be nice. I have no such plan ... But you
339 can:</p>
340 <ul>
341 <li>check more deeply the <a href="html/libxml-lib.html">existing
342 generated doc</a></li>
343 <li>looks for examples of use for libxml function using the Gnome code
344 for example the following will query the full Gnome CVs base for the
345 use of the <strong>xmlAddChild()</strong> function:
346 <p><a
347 href="http://cvs.gnome.org/lxr/search?string=xmlAddChild">http://cvs.gnome.org/lxr/search?string=xmlAddChild</a></p>
348 <p>This may be slow, a large hardware donation to the gnome project
349 could cure this :-)</p>
350 </li>
351 <li><a
352 href="http://cvs.gnome.org/bonsai/rview.cgi?cvsroot=/cvs/gnome&amp;dir=gnome-xml">Browse
353 the libxml source</a>
354 , I try to write code as clean and documented as possible, so
355 looking at it may be helpful</li>
356 </ul>
357 </li>
358 <li>What about C++ ?
359 <p>libxml is written in pure C in order to allow easy reuse on a number
360 of platforms, including embedded systems. I don't intend to convert to
361 C++.</p>
362 <p>There is however a C++ wrapper provided by Ari Johnson
363 &lt;ari@btigate.com&gt; which may fullfill your needs:</p>
364 <p>Website: <a
365 href="http://lusis.org/~ari/xml++/">http://lusis.org/~ari/xml++/</a></p>
366 <p>Download: <a
367 href="http://lusis.org/~ari/xml++/libxml++.tar.gz">http://lusis.org/~ari/xml++/libxml++.tar.gz</a></p>
368 </li>
369 <li>How to validate a document a posteriori ?
370 <p>It is possible to validate documents which had not been validated at
371 initial parsing time or documents who have been built from scratch using
372 the API. Use the <a
373 href="http://xmlsoft.org/html/libxml-valid.html#XMLVALIDATEDTD">xmlValidateDtd()</a>
374 function. It is also possible to simply add a Dtd to an existing
375 document:</p>
376 <pre>xmlDocPtr doc; /* your existing document */
377 xmlDtdPtr dtd = xmlParseDTD(NULL, filename_of_dtd); /* parse the DTD */
378 dtd-&gt;name = xmlStrDup((xmlChar*)"root_name"); /* use the given root */
379
380 doc-&gt;intSubset = dtd;
381 if (doc-&gt;children == NULL) xmlAddChild((xmlNodePtr)doc, (xmlNodePtr)dtd);
382 else xmlAddPrevSibling(doc-&gt;children, (xmlNodePtr)dtd);
383 </pre>
384 </li>
385 <li>etc ...</li>
386</ol>
387
388<p></p>
389
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]390<h2><a name="Documentat">Documentation</a></h2>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]391
Daniel Veillard402e8c82000-02-29 22:57:47 +0000[diff] [blame]392<p>There are some on-line resources about using libxml:</p>
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]393<ol>
Daniel Veillard365e13b2000-07-02 07:56:37 +0000[diff] [blame]394 <li>Check the <a href="FAQ.html">FAQ</a></li>
Daniel Veillardc19fccc2000-07-03 11:52:01 +0000[diff] [blame]395 <li>Check the <a href="http://xmlsoft.org/html/libxml-lib.html">extensive
Daniel Veillard8c6d6af2000-08-25 17:14:13 +0000[diff] [blame]396 documentation</a> automatically extracted from code comments (using <a
397 href="http://cvs.gnome.org/bonsai/rview.cgi?cvsroot=/cvs/gnome&amp;dir=gtk-doc">gtk
398 doc</a>).</li>
Daniel Veillard8d869642000-07-14 12:12:59 +0000[diff] [blame]399 <li>Look at the documentation about <a href="encoding.html">libxml
400 internationalization support</a></li>
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]401 <li>This page provides a global overview and <a href="#real">some
Daniel Veillard402e8c82000-02-29 22:57:47 +0000[diff] [blame]402 examples</a> on how to use libxml.</li>
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]403 <li><a href="mailto:james@daa.com.au">James Henstridge</a>
404 wrote <a
Daniel Veillard402e8c82000-02-29 22:57:47 +0000[diff] [blame]405 href="http://www.daa.com.au/~james/gnome/xml-sax/xml-sax.html">some nice
406 documentation</a> explaining how to use the libxml SAX interface.</li>
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]407 <li>George Lebl wrote <a
408 href="http://www-4.ibm.com/software/developer/library/gnome3/">an article
Daniel Veillard402e8c82000-02-29 22:57:47 +0000[diff] [blame]409 for IBM developerWorks</a> about using libxml.</li>
Daniel Veillardec303412000-03-24 13:41:54 +0000[diff] [blame]410 <li>Check <a href="http://cvs.gnome.org/lxr/source/gnome-xml/TODO">the TODO
411 file</a></li>
412 <li>Read the <a href="upgrade.html">1.x to 2.x upgrade path</a>. If you are
413 starting a new project using libxml you should really use the 2.x
414 version.</li>
Daniel Veillard845cce42002-01-09 11:51:37 +0000[diff] [blame^]415 <li>And don't forget to look at the <a
416 href="http://mail.gnome.org/archives/xml/">mailing-list archive</a>.</li>
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]417</ol>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]418
Daniel Veillardd5f97f82000-09-17 16:38:14 +0000[diff] [blame]419<h2><a name="Reporting">Reporting bugs and getting help</a></h2>
Daniel Veillard4c3a2031999-11-19 17:46:26 +0000[diff] [blame]420
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]421<p>Well, bugs or missing features are always possible, and I will make a
422point of fixing them in a timely fashion. The best way to report a bug is to
423use the <a href="http://bugzilla.gnome.org/buglist.cgi?product=libxml">Gnome
424bug tracking database</a> (make sure to use the "libxml" module name). I look
425at 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]426still open. Be sure to specify that the bug is for the package libxml.</p>
Daniel Veillard4c3a2031999-11-19 17:46:26 +0000[diff] [blame]427
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]428<p>There is also a mailing-list <a
Daniel Veillard3197f162001-04-04 00:40:08 +0000[diff] [blame]429href="mailto:xml@gnome.org">xml@gnome.org</a> for libxml, with an <a
430href="http://mail.gnome.org/archives/xml/">on-line archive</a> (<a
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]431href="http://xmlsoft.org/messages">old</a>). To subscribe to this list,
432please visit the <a
433href="http://mail.gnome.org/mailman/listinfo/xml">associated Web</a> page and
434follow the instructions. <strong>Do not send code, I won't debug it</strong>
435(but patches are really appreciated!).</p>
Daniel Veillard234547b2001-07-05 09:46:10 +0000[diff] [blame]436
Daniel Veillard008186f2001-09-13 14:24:44 +0000[diff] [blame]437<p>Check the following <strong><span style="color: #FF0000">before
438posting</span></strong>:</p>
Daniel Veillard234547b2001-07-05 09:46:10 +0000[diff] [blame]439<ul>
Daniel Veillarddadd0872001-09-15 09:21:44 +0000[diff] [blame]440 <li>read the <a href="FAQ.html">FAQ</a></li>
Daniel Veillard234547b2001-07-05 09:46:10 +0000[diff] [blame]441 <li>make sure you are <a href="ftp://xmlsoft.org/">using a recent
442 version</a>, and that the problem still shows up in those</li>
443 <li>check the <a href="http://mail.gnome.org/archives/xml/">list
444 archives</a> to see if the problem was reported already, in this case
Daniel Veillarde7ead2d2001-08-22 23:44:09 +0000[diff] [blame]445 there is probably a fix available, similary check the <a
446 href="http://bugzilla.gnome.org/buglist.cgi?product=libxml">registered
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]447 open bugs</a></li>
Daniel Veillard234547b2001-07-05 09:46:10 +0000[diff] [blame]448 <li>make sure you can reproduce the bug with xmllint or one of the test
449 programs found in source in the distribution</li>
450 <li>Please send the command showing the error as well as the input (as an
451 attachement)</li>
452</ul>
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]453
Daniel Veillarddadd0872001-09-15 09:21:44 +0000[diff] [blame]454<p>Then send the bug with associated informations to reproduce it to the <a
Daniel Veillard33a67802001-03-07 09:44:02 +0000[diff] [blame]455href="mailto:xml@gnome.org">xml@gnome.org</a> list; if it's really libxml
Daniel Veillard008186f2001-09-13 14:24:44 +0000[diff] [blame]456related I will approve it.. Please do not send me mail directly, it makes
457things really harder to track and in some cases I'm not the best person to
458answer a given question, ask the list instead.</p>
Daniel Veillard4c3a2031999-11-19 17:46:26 +0000[diff] [blame]459
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]460<p>Of course, bugs reported with a suggested patch for fixing them will
Daniel Veillardec303412000-03-24 13:41:54 +0000[diff] [blame]461probably be processed faster.</p>
462
463<p>If you're looking for help, a quick look at <a
Daniel Veillardf7ed3362001-08-17 12:01:21 +0000[diff] [blame]464href="http://mail.gnome.org/archives/xml/">the list archive</a> may actually
Daniel Veillardec303412000-03-24 13:41:54 +0000[diff] [blame]465provide the answer, I usually send source samples when answering libxml usage
Daniel Veillard6f0adb52000-07-03 11:41:26 +0000[diff] [blame]466questions. The <a href="http://xmlsoft.org/html/book1.html">auto-generated
Daniel Veillardec303412000-03-24 13:41:54 +0000[diff] [blame]467documentantion</a> is not as polished as I would like (i need to learn more
468about Docbook), but it's a good starting point.</p>
469
Daniel Veillardd5f97f82000-09-17 16:38:14 +0000[diff] [blame]470<h2><a name="help">How to help</a></h2>
471
472<p>You can help the project in various ways, the best thing to do first is to
473subscribe to the mailing-list as explained before, check the <a
Daniel Veillardf7ed3362001-08-17 12:01:21 +0000[diff] [blame]474href="http://mail.gnome.org/archives/xml/">archives </a>and the <a
475href="http://bugzilla.gnome.org/buglist.cgi?product=libxml">Gnome bug
Daniel Veillardd5f97f82000-09-17 16:38:14 +0000[diff] [blame]476database:</a>:</p>
477<ol>
478 <li>provide patches when you find problems</li>
Daniel Veillard189446d2000-10-13 10:23:06 +0000[diff] [blame]479 <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]480 be integrated in all cases but help pinpointing portability problems
481 and</li>
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]482 <li>provide documentation fixes (either as patches to the code comments or
Daniel Veillardd5f97f82000-09-17 16:38:14 +0000[diff] [blame]483 as HTML diffs).</li>
484 <li>provide new documentations pieces (translations, examples, etc ...)</li>
485 <li>Check the TODO file and try to close one of the items</li>
486 <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]487 provide a fix. <a href="mailto:daniel@veillard.com">Get in touch with me
488 </a>before to avoid synchronization problems and check that the suggested
489 fix will fit in nicely :-)</li>
Daniel Veillardd5f97f82000-09-17 16:38:14 +0000[diff] [blame]490</ol>
491
Daniel Veillard10a2c651999-12-12 13:03:50 +0000[diff] [blame]492<h2><a name="Downloads">Downloads</a></h2>
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]493
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]494<p>The latest versions of libxml can be found on <a
Daniel Veillard20c8cf22001-06-26 22:47:36 +0000[diff] [blame]495href="ftp://xmlsoft.org/">xmlsoft.org</a> (<a
496href="ftp://speakeasy.rpmfind.net/pub/libxml/">Seattle</a>, <a
497href="ftp://fr.rpmfind.net/pub/libxml/">France</a>) or on the <a
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]498href="ftp://ftp.gnome.org/pub/GNOME/MIRRORS.html">Gnome FTP server</a> either
Daniel Veillard10a2c651999-12-12 13:03:50 +0000[diff] [blame]499as a <a href="ftp://ftp.gnome.org/pub/GNOME/stable/sources/libxml/">source
Daniel Veillard306be992000-07-03 12:38:45 +0000[diff] [blame]500archive</a> or <a
Daniel Veillarda41123c2001-04-22 19:31:20 +0000[diff] [blame]501href="ftp://ftp.gnome.org/pub/GNOME/stable/redhat/i386/libxml/">RPM
502packages</a>. (NOTE that you need both the <a
Daniel Veillardc19fccc2000-07-03 11:52:01 +0000[diff] [blame]503href="http://rpmfind.net/linux/RPM/libxml2.html">libxml(2)</a> and <a
504href="http://rpmfind.net/linux/RPM/libxml2-devel.html">libxml(2)-devel</a>
Daniel Veillard95189532001-07-26 18:30:26 +0000[diff] [blame]505packages installed to compile applications using libxml.) <a
506href="mailto:izlatkovic@daenet.de">Igor Zlatkovic</a> is now the maintainer
507of the Windows port, <a
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]508href="http://www.fh-frankfurt.de/~igor/projects/libxml/index.html">he
Daniel Veillardc6271d22001-10-27 07:50:58 +0000[diff] [blame]509provides binaries</a>. <a href="mailto:Gary.Pennington@sun.com">Gary
Daniel Veillard1aadc442001-11-28 13:10:32 +0000[diff] [blame]510Pennington</a> provides <a href="http://garypennington.net/libxml2/">Solaris
511binaries</a>.</p>
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]512
Daniel Veillard6c8b1172000-03-01 00:40:41 +0000[diff] [blame]513<p><a name="Snapshot">Snapshot:</a></p>
514<ul>
515 <li>Code from the W3C cvs base libxml <a
Daniel Veillard33a67802001-03-07 09:44:02 +0000[diff] [blame]516 href="ftp://xmlsoft.org/cvs-snapshot.tar.gz">cvs-snapshot.tar.gz</a></li>
Daniel Veillard6c8b1172000-03-01 00:40:41 +0000[diff] [blame]517 <li>Docs, content of the web site, the list archive included <a
Daniel Veillard33a67802001-03-07 09:44:02 +0000[diff] [blame]518 href="ftp://xmlsoft.org/libxml-docs.tar.gz">libxml-docs.tar.gz</a></li>
Daniel Veillard6c8b1172000-03-01 00:40:41 +0000[diff] [blame]519</ul>
520
Daniel Veillardc6271d22001-10-27 07:50:58 +0000[diff] [blame]521<p><a name="Contribs">Contributions:</a></p>
Daniel Veillard6c8b1172000-03-01 00:40:41 +0000[diff] [blame]522
523<p>I do accept external contributions, especially if compiling on another
Daniel Veillardc6271d22001-10-27 07:50:58 +0000[diff] [blame]524platform, get in touch with me to upload the package, wrappers for various
Daniel Veillard51095312001-10-28 18:51:57 +0000[diff] [blame]525languages have been provided, and can be found in the <a
526href="contribs.html">contrib section</a></p>
Daniel Veillard6c8b1172000-03-01 00:40:41 +0000[diff] [blame]527
Daniel Veillard82687162001-01-22 15:32:01 +0000[diff] [blame]528<p>Libxml is also available from CVS:</p>
Daniel Veillard10a2c651999-12-12 13:03:50 +0000[diff] [blame]529<ul>
Daniel Veillard10a2c651999-12-12 13:03:50 +0000[diff] [blame]530 <li><p>The <a
531 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]532 CVS base</a>. Check the <a
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]533 href="http://developer.gnome.org/tools/cvs.html">Gnome CVS Tools</a>
534 page; the CVS module is <b>gnome-xml</b>.</p>
Daniel Veillard10a2c651999-12-12 13:03:50 +0000[diff] [blame]535 </li>
Daniel Veillard82687162001-01-22 15:32:01 +0000[diff] [blame]536 <li>The <strong>libxslt</strong> module is also present there</li>
Daniel Veillard10a2c651999-12-12 13:03:50 +0000[diff] [blame]537</ul>
538
539<h2><a name="News">News</a></h2>
540
Daniel Veillard944b5ff1999-12-15 19:08:24 +0000[diff] [blame]541<h3>CVS only : check the <a
542href="http://cvs.gnome.org/lxr/source/gnome-xml/ChangeLog">Changelog</a> file
Daniel Veillard189446d2000-10-13 10:23:06 +0000[diff] [blame]543for a really accurate description</h3>
Daniel Veillardab8500d2000-10-15 21:06:19 +0000[diff] [blame]544
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]545<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]546you want to test those</p>
547<ul>
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]548 <li>Implementing <a href="http://xmlsoft.org/XSLT">XSLT</a>, this is done
549 as a separate C library on top of libxml called libxslt</li>
Daniel Veillard28929b22000-11-13 18:22:49 +0000[diff] [blame]550 <li>Finishing up <a href="http://www.w3.org/TR/xptr">XPointer</a> and <a
551 href="http://www.w3.org/TR/xinclude">XInclude</a></li>
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]552 <li>(seeems working but delayed from release) parsing/import of Docbook
553 SGML docs</li>
554</ul>
555
Daniel Veillardef90ba72001-12-07 14:24:22 +0000[diff] [blame]556<h3>2.4.12: Dec 7 2001</h3>
557<ul>
558 <li>a few bug fixes: thread (Gary Pennington), xmllint (Geert Kloosterman),
559 XML parser (Robin Berjon), XPointer (Danny Jamshy), I/O cleanups
560 (robert)</li>
561 <li>Eric Lavigne contributed project files for MacOS</li>
562 <li>some makefiles cleanups</li>
563</ul>
564
Daniel Veillarda4871052001-11-26 13:19:48 +0000[diff] [blame]565<h3>2.4.11: Nov 26 2001</h3>
566<ul>
567 <li>fixed a couple of errors in the includes, fixed a few bugs, some code
568 cleanups</li>
569 <li>xmllint man pages improvement by Heiko Rupp</li>
570 <li>updated VMS build instructions from John A Fotheringham</li>
571 <li>Windows Makefiles updates from Igor</li>
572</ul>
573
Daniel Veillard43d3f612001-11-10 11:57:23 +0000[diff] [blame]574<h3>2.4.10: Nov 10 2001</h3>
575<ul>
576 <li>URI escaping fix (Joel Young)</li>
577 <li>added xmlGetNodePath() (for paths or XPointers generation)</li>
578 <li>Fixes namespace handling problems when using DTD and validation</li>
579 <li>improvements on xmllint: Morus Walter patches for --format and
580 --encode, Stefan Kost and Heiko Rupp improvements on the --shell</li>
581 <li>fixes for xmlcatalog linking pointed by Weiqi Gao</li>
582 <li>fixes to the HTML parser</li>
583</ul>
584
585<h3>2.4.9: Nov 6 2001</h3>
586<ul>
587 <li>fixes more catalog bugs</li>
588 <li>avoid a compilation problem, improve xmlGetLineNo()</li>
589</ul>
590
Daniel Veillarded421aa2001-11-04 21:22:45 +0000[diff] [blame]591<h3>2.4.8: Nov 4 2001</h3>
592<ul>
593 <li>fixed SGML catalogs broken in previous release, updated xmlcatalog
594 tool</li>
595 <li>fixed a compile errors and some includes troubles.</li>
596</ul>
597
Daniel Veillard52dcab32001-10-30 12:51:17 +0000[diff] [blame]598<h3>2.4.7: Oct 30 2001</h3>
599<ul>
600 <li>exported some debugging interfaces</li>
601 <li>serious rewrite of the catalog code</li>
602 <li>integrated Gary Pennington thread safety patch, added configure option
603 and regression tests</li>
604 <li>removed an HTML parser bug</li>
605 <li>fixed a couple of potentially serious validation bugs</li>
606 <li>integrated the SGML DocBook support in xmllint</li>
607 <li>changed the nanoftp anonymous login passwd</li>
608 <li>some I/O cleanup and a couple of interfaces for Perl wrapper</li>
609 <li>general bug fixes</li>
610 <li>updated xmllint man page by John Fleck</li>
611 <li>some VMS and Windows updates</li>
612</ul>
613
Daniel Veillard60087f32001-10-10 09:45:09 +0000[diff] [blame]614<h3>2.4.6: Oct 10 2001</h3>
615<ul>
Daniel Veillard52dcab32001-10-30 12:51:17 +0000[diff] [blame]616 <li>added an updated man pages by John Fleck</li>
Daniel Veillard60087f32001-10-10 09:45:09 +0000[diff] [blame]617 <li>portability and configure fixes</li>
618 <li>an infinite loop on the HTML parser was removed (William)</li>
619 <li>Windows makefile patches from Igor</li>
620 <li>fixed half a dozen bugs reported fof libxml or libxslt</li>
621 <li>updated xmlcatalog to be able to modify SGML super catalogs</li>
622</ul>
623
Daniel Veillarddadd0872001-09-15 09:21:44 +0000[diff] [blame]624<h3>2.4.5: Sep 14 2001</h3>
625<ul>
626 <li>Remove a few annoying bugs in 2.4.4</li>
627 <li>forces the HTML serializer to output decimal charrefs since some
628 version of Netscape can't handle hexadecimal ones</li>
629</ul>
630
631<h3>1.8.16: Sep 14 2001</h3>
632<ul>
633 <li>maintenance release of the old libxml1 branch, couple of bug and
634 portability fixes</li>
635</ul>
636
Daniel Veillard04382ae2001-09-12 18:51:30 +0000[diff] [blame]637<h3>2.4.4: Sep 12 2001</h3>
638<ul>
639 <li>added --convert to xmlcatalog, bug fixes and cleanups of XML
640 Catalog</li>
641 <li>a few bug fixes and some portability changes</li>
642 <li>some documentation cleanups</li>
643</ul>
644
Daniel Veillard39936902001-08-24 00:49:01 +0000[diff] [blame]645<h3>2.4.3: Aug 23 2001</h3>
646<ul>
647 <li>XML Catalog support see the doc</li>
648 <li>New NaN/Infinity floating point code</li>
649 <li>A few bug fixes</li>
650</ul>
651
652<h3>2.4.2: Aug 15 2001</h3>
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]653<ul>
654 <li>adds xmlLineNumbersDefault() to control line number generation</li>
655 <li>lot of bug fixes</li>
656 <li>the Microsoft MSC projects files shuld now be up to date</li>
657 <li>inheritance of namespaces from DTD defaulted attributes</li>
658 <li>fixes a serious potential security bug</li>
659 <li>added a --format option to xmllint</li>
660</ul>
661
662<h3>2.4.1: July 24 2001</h3>
663<ul>
664 <li>possibility to keep line numbers in the tree</li>
665 <li>some computation NaN fixes</li>
666 <li>extension of the XPath API</li>
667 <li>cleanup for alpha and ia64 targets</li>
668 <li>patch to allow saving through HTTP PUT or POST</li>
Daniel Veillard09ab7e12001-07-10 15:49:44 +0000[diff] [blame]669</ul>
670
671<h3>2.4.0: July 10 2001</h3>
672<ul>
673 <li>Fixed a few bugs in XPath, validation, and tree handling.</li>
674 <li>Fixed XML Base implementation, added a coupel of examples to the
675 regression tests</li>
676 <li>A bit of cleanup</li>
Daniel Veillardab8500d2000-10-15 21:06:19 +0000[diff] [blame]677</ul>
678
Daniel Veillard5b43fde2001-07-05 23:31:40 +0000[diff] [blame]679<h3>2.3.14: July 5 2001</h3>
680<ul>
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]681 <li>fixed some entities problems and reduce mem requirement when
682 substituing them</li>
Daniel Veillard5b43fde2001-07-05 23:31:40 +0000[diff] [blame]683 <li>lots of improvements in the XPath queries interpreter can be
684 substancially faster</li>
685 <li>Makefiles and configure cleanups</li>
686 <li>Fixes to XPath variable eval, and compare on empty node set</li>
687 <li>HTML tag closing bug fixed</li>
688 <li>Fixed an URI reference computating problem when validating</li>
689</ul>
690
Daniel Veillard2adbb512001-06-28 16:20:36 +0000[diff] [blame]691<h3>2.3.13: June 28 2001</h3>
692<ul>
693 <li>2.3.12 configure.in was broken as well as the push mode XML parser</li>
694 <li>a few more fixes for compilation on Windows MSC by Yon Derek</li>
695</ul>
696
697<h3>1.8.14: June 28 2001</h3>
698<ul>
699 <li>Zbigniew Chyla gave a patch to use the old XML parser in push mode</li>
700 <li>Small Makefile fix</li>
701</ul>
702
Daniel Veillard11648102001-06-26 16:08:24 +0000[diff] [blame]703<h3>2.3.12: June 26 2001</h3>
704<ul>
705 <li>lots of cleanup</li>
706 <li>a couple of validation fix</li>
707 <li>fixed line number counting</li>
708 <li>fixed serious problems in the XInclude processing</li>
709 <li>added support for UTF8 BOM at beginning of entities</li>
710 <li>fixed a strange gcc optimizer bugs in xpath handling of float, gcc-3.0
711 miscompile uri.c (William), Thomas Leitner provided a fix for the
712 optimizer on Tru64</li>
713 <li>incorporated Yon Derek and Igor Zlatkovic fixes and improvements for
714 compilation on Windows MSC</li>
715 <li>update of libxml-doc.el (Felix Natter)</li>
716 <li>fixed 2 bugs in URI normalization code</li>
717</ul>
718
Daniel Veillarde3c81b52001-06-17 14:50:34 +0000[diff] [blame]719<h3>2.3.11: June 17 2001</h3>
720<ul>
721 <li>updates to trio, Makefiles and configure should fix some portability
722 problems (alpha)</li>
723 <li>fixed some HTML serialization problems (pre, script, and block/inline
724 handling), added encoding aware APIs, cleanup of this code</li>
725 <li>added xmlHasNsProp()</li>
726 <li>implemented a specific PI for encoding support in the DocBook SGML
727 parser</li>
728 <li>some XPath fixes (-Infinity, / as a function parameter and namespaces
729 node selection)</li>
730 <li>fixed a performance problem and an error in the validation code</li>
731 <li>fixed XInclude routine to implement the recursive behaviour</li>
732 <li>fixed xmlFreeNode problem when libxml is included statically twice</li>
733 <li>added --version to xmllint for bug reports</li>
734</ul>
735
Daniel Veillard2e4f1882001-06-01 10:11:57 +0000[diff] [blame]736<h3>2.3.10: June 1 2001</h3>
737<ul>
738 <li>fixed the SGML catalog support</li>
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]739 <li>a number of reported bugs got fixed, in XPath, iconv detection,
740 XInclude processing</li>
Daniel Veillard2e4f1882001-06-01 10:11:57 +0000[diff] [blame]741 <li>XPath string function should now handle unicode correctly</li>
742</ul>
743
Daniel Veillard4623acd2001-05-19 15:13:15 +0000[diff] [blame]744<h3>2.3.9: May 19 2001</h3>
745
746<p>Lots of bugfixes, and added a basic SGML catalog support:</p>
747<ul>
748 <li>HTML push bugfix #54891 and another patch from Jonas Borgström</li>
749 <li>some serious speed optimisation again</li>
750 <li>some documentation cleanups</li>
751 <li>trying to get better linking on solaris (-R)</li>
752 <li>XPath API cleanup from Thomas Broyer</li>
753 <li>Validation bug fixed #54631, added a patch from Gary Pennington, fixed
754 xmlValidGetValidElements()</li>
755 <li>Added an INSTALL file</li>
756 <li>Attribute removal added to API: #54433</li>
757 <li>added a basic support for SGML catalogs</li>
758 <li>fixed xmlKeepBlanksDefault(0) API</li>
759 <li>bugfix in xmlNodeGetLang()</li>
760 <li>fixed a small configure portability problem</li>
761 <li>fixed an inversion of SYSTEM and PUBLIC identifier in HTML document</li>
762</ul>
763
Daniel Veillarda265af72001-05-14 11:13:58 +0000[diff] [blame]764<h3>1.8.13: May 14 2001</h3>
765<ul>
766 <li>bugfixes release of the old libxml1 branch used by Gnome</li>
767</ul>
768
Daniel Veillard3bbbe6f2001-05-03 11:15:37 +0000[diff] [blame]769<h3>2.3.8: May 3 2001</h3>
770<ul>
771 <li>Integrated an SGML DocBook parser for the Gnome project</li>
772 <li>Fixed a few things in the HTML parser</li>
773 <li>Fixed some XPath bugs raised by XSLT use, tried to fix the floating
774 point portability issue</li>
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]775 <li>Speed improvement (8M/s for SAX, 3M/s for DOM, 1.5M/s for
776 DOM+validation using the XML REC as input and a 700MHz celeron).</li>
Daniel Veillard3bbbe6f2001-05-03 11:15:37 +0000[diff] [blame]777 <li>incorporated more Windows cleanup</li>
778 <li>added xmlSaveFormatFile()</li>
779 <li>fixed problems in copying nodes with entities references (gdome)</li>
780 <li>removed some troubles surrounding the new validation module</li>
781</ul>
782
Daniel Veillarda41123c2001-04-22 19:31:20 +0000[diff] [blame]783<h3>2.3.7: April 22 2001</h3>
784<ul>
785 <li>lots of small bug fixes, corrected XPointer</li>
786 <li>Non determinist content model validation support</li>
787 <li>added xmlDocCopyNode for gdome2</li>
788 <li>revamped the way the HTML parser handles end of tags</li>
789 <li>XPath: corrctions of namespacessupport and number formatting</li>
790 <li>Windows: Igor Zlatkovic patches for MSC compilation</li>
791 <li>HTML ouput fixes from P C Chow and William M. Brack</li>
792 <li>Improved validation speed sensible for DocBook</li>
793 <li>fixed a big bug with ID declared in external parsed entities</li>
794 <li>portability fixes, update of Trio from Bjorn Reese</li>
795</ul>
796
Daniel Veillardafc73112001-04-11 11:51:41 +0000[diff] [blame]797<h3>2.3.6: April 8 2001</h3>
798<ul>
799 <li>Code cleanup using extreme gcc compiler warning options, found and
800 cleared half a dozen potential problem</li>
801 <li>the Eazel team found an XML parser bug</li>
802 <li>cleaned up the user of some of the string formatting function. used the
803 trio library code to provide the one needed when the platform is missing
804 them</li>
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]805 <li>xpath: removed a memory leak and fixed the predicate evaluation
806 problem, extended the testsuite and cleaned up the result. XPointer seems
807 broken ...</li>
Daniel Veillardafc73112001-04-11 11:51:41 +0000[diff] [blame]808</ul>
809
Daniel Veillard56a4cb82001-03-24 17:00:36 +0000[diff] [blame]810<h3>2.3.5: Mar 23 2001</h3>
811<ul>
812 <li>Biggest change is separate parsing and evaluation of XPath expressions,
813 there is some new APIs for this too</li>
814 <li>included a number of bug fixes(XML push parser, 51876, notations,
815 52299)</li>
816 <li>Fixed some portability issues</li>
817</ul>
818
Daniel Veillarde356c282001-03-10 12:32:04 +0000[diff] [blame]819<h3>2.3.4: Mar 10 2001</h3>
820<ul>
821 <li>Fixed bugs #51860 and #51861</li>
822 <li>Added a global variable xmlDefaultBufferSize to allow default buffer
823 size to be application tunable.</li>
824 <li>Some cleanup in the validation code, still a bug left and this part
825 should probably be rewritten to support ambiguous content model :-\</li>
826 <li>Fix a couple of serious bugs introduced or raised by changes in 2.3.3
827 parser</li>
828 <li>Fixed another bug in xmlNodeGetContent()</li>
829 <li>Bjorn fixed XPath node collection and Number formatting</li>
830 <li>Fixed a loop reported in the HTML parsing</li>
831 <li>blank space are reported even if the Dtd content model proves that they
832 are formatting spaces, this is for XmL conformance</li>
833</ul>
834
Daniel Veillardb402c072001-03-01 17:28:58 +0000[diff] [blame]835<h3>2.3.3: Mar 1 2001</h3>
836<ul>
837 <li>small change in XPath for XSLT</li>
838 <li>documentation cleanups</li>
839 <li>fix in validation by Gary Pennington</li>
840 <li>serious parsing performances improvements</li>
841</ul>
842
Daniel Veillardec70e912001-02-26 20:10:45 +0000[diff] [blame]843<h3>2.3.2: Feb 24 2001</h3>
Daniel Veillard71681102001-02-24 17:48:53 +0000[diff] [blame]844<ul>
845 <li>chasing XPath bugs, found a bunch, completed some TODO</li>
846 <li>fixed a Dtd parsing bug</li>
847 <li>fixed a bug in xmlNodeGetContent</li>
848 <li>ID/IDREF support partly rewritten by Gary Pennington</li>
849</ul>
850
Daniel Veillardec70e912001-02-26 20:10:45 +0000[diff] [blame]851<h3>2.3.1: Feb 15 2001</h3>
Daniel Veillard6e6a6cc2001-02-15 15:55:44 +0000[diff] [blame]852<ul>
853 <li>some XPath and HTML bug fixes for XSLT</li>
854 <li>small extension of the hash table interfaces for DOM gdome2
855 implementation</li>
856 <li>A few bug fixes</li>
857</ul>
858
Daniel Veillardec70e912001-02-26 20:10:45 +0000[diff] [blame]859<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]860<ul>
861 <li>Lots of XPath bug fixes</li>
862 <li>Add a mode with Dtd lookup but without validation error reporting for
863 XSLT</li>
864 <li>Add support for text node without escaping (XSLT)</li>
865 <li>bug fixes for xmlCheckFilename</li>
866 <li>validation code bug fixes from Gary Pennington</li>
867 <li>Patch from Paul D. Smith correcting URI path normalization</li>
868 <li>Patch to allow simultaneous install of libxml-devel and
869 libxml2-devel</li>
870 <li>the example Makefile is now fixed</li>
871 <li>added HTML to the RPM packages</li>
872 <li>tree copying bugfixes</li>
873 <li>updates to Windows makefiles</li>
874 <li>optimisation patch from Bjorn Reese</li>
875</ul>
876
Daniel Veillardec70e912001-02-26 20:10:45 +0000[diff] [blame]877<h3>2.2.11: Jan 4 2001</h3>
Daniel Veillard503b8932001-01-05 06:36:31 +0000[diff] [blame]878<ul>
879 <li>bunch of bug fixes (memory I/O, xpath, ftp/http, ...)</li>
880 <li>added htmlHandleOmittedElem()</li>
881 <li>Applied Bjorn Reese's IPV6 first patch</li>
882 <li>Applied Paul D. Smith patches for validation of XInclude results</li>
Daniel Veillard82687162001-01-22 15:32:01 +0000[diff] [blame]883 <li>added XPointer xmlns() new scheme support</li>
Daniel Veillard503b8932001-01-05 06:36:31 +0000[diff] [blame]884</ul>
885
Daniel Veillard2ddd23d2000-11-25 10:42:19 +0000[diff] [blame]886<h3>2.2.10: Nov 25 2000</h3>
Daniel Veillard9d343c42000-11-25 10:12:43 +0000[diff] [blame]887<ul>
888 <li>Fix the Windows problems of 2.2.8</li>
889 <li>integrate OpenVMS patches</li>
890 <li>better handling of some nasty HTML input</li>
891 <li>Improved the XPointer implementation</li>
892 <li>integrate a number of provided patches</li>
893</ul>
894
Daniel Veillard2ddd23d2000-11-25 10:42:19 +0000[diff] [blame]895<h3>2.2.9: Nov 25 2000</h3>
896<ul>
897 <li>erroneous release :-(</li>
898</ul>
899
Daniel Veillard28929b22000-11-13 18:22:49 +0000[diff] [blame]900<h3>2.2.8: Nov 13 2000</h3>
901<ul>
902 <li>First version of <a href="http://www.w3.org/TR/xinclude">XInclude</a>
903 support</li>
904 <li>Patch in conditional section handling</li>
905 <li>updated MS compiler project</li>
906 <li>fixed some XPath problems</li>
907 <li>added an URI escaping function</li>
908 <li>some other bug fixes</li>
909</ul>
910
911<h3>2.2.7: Oct 31 2000</h3>
912<ul>
913 <li>added message redirection</li>
914 <li>XPath improvements (thanks TOM !)</li>
915 <li>xmlIOParseDTD() added</li>
916 <li>various small fixes in the HTML, URI, HTTP and XPointer support</li>
917 <li>some cleanup of the Makefile, autoconf and the distribution content</li>
918</ul>
919
Daniel Veillard29a11cc2000-10-25 13:32:39 +0000[diff] [blame]920<h3>2.2.6: Oct 25 2000:</h3>
921<ul>
922 <li>Added an hash table module, migrated a number of internal structure to
923 those</li>
924 <li>Fixed a posteriori validation problems</li>
925 <li>HTTP module cleanups</li>
926 <li>HTML parser improvements (tag errors, script/style handling, attribute
927 normalization)</li>
928 <li>coalescing of adjacent text nodes</li>
929 <li>couple of XPath bug fixes, exported the internal API</li>
930</ul>
931
Daniel Veillardab8500d2000-10-15 21:06:19 +0000[diff] [blame]932<h3>2.2.5: Oct 15 2000:</h3>
Daniel Veillard4c3a2031999-11-19 17:46:26 +0000[diff] [blame]933<ul>
Daniel Veillard189446d2000-10-13 10:23:06 +0000[diff] [blame]934 <li>XPointer implementation and testsuite</li>
935 <li>Lot of XPath fixes, added variable and functions registration, more
936 tests</li>
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]937 <li>Portability fixes, lots of enhancements toward an easy Windows build
938 and release</li>
Daniel Veillard189446d2000-10-13 10:23:06 +0000[diff] [blame]939 <li>Late validation fixes</li>
940 <li>Integrated a lot of contributed patches</li>
941 <li>added memory management docs</li>
Daniel Veillardab8500d2000-10-15 21:06:19 +0000[diff] [blame]942 <li>a performance problem when using large buffer seems fixed</li>
Daniel Veillard189446d2000-10-13 10:23:06 +0000[diff] [blame]943</ul>
944
945<h3>2.2.4: Oct 1 2000:</h3>
946<ul>
947 <li>main XPath problem fixed</li>
948 <li>Integrated portability patches for Windows</li>
949 <li>Serious bug fixes on the URI and HTML code</li>
Daniel Veillard361d8452000-04-03 19:48:13 +0000[diff] [blame]950</ul>
951
Daniel Veillardd5f97f82000-09-17 16:38:14 +0000[diff] [blame]952<h3>2.2.3: Sep 17 2000</h3>
953<ul>
954 <li>bug fixes</li>
955 <li>cleanup of entity handling code</li>
956 <li>overall review of all loops in the parsers, all sprintf usage has been
957 checked too</li>
958 <li>Far better handling of larges Dtd. Validating against Docbook XML Dtd
959 works smoothly now.</li>
960</ul>
961
962<h3>1.8.10: Sep 6 2000</h3>
963<ul>
964 <li>bug fix release for some Gnome projects</li>
965</ul>
966
967<h3>2.2.2: August 12 2000</h3>
Daniel Veillard786d7c82000-08-12 23:38:57 +0000[diff] [blame]968<ul>
969 <li>mostly bug fixes</li>
Daniel Veillardec78c0f2000-08-25 10:25:23 +0000[diff] [blame]970 <li>started adding routines to access xml parser context options</li>
Daniel Veillard786d7c82000-08-12 23:38:57 +0000[diff] [blame]971</ul>
972
Daniel Veillardd5f97f82000-09-17 16:38:14 +0000[diff] [blame]973<h3>2.2.1: July 21 2000</h3>
Daniel Veillarda2679fa2000-07-22 02:38:15 +0000[diff] [blame]974<ul>
975 <li>a purely bug fixes release</li>
976 <li>fixed an encoding support problem when parsing from a memory block</li>
977 <li>fixed a DOCTYPE parsing problem</li>
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]978 <li>removed a bug in the function allowing to override the memory
979 allocation routines</li>
Daniel Veillarda2679fa2000-07-22 02:38:15 +0000[diff] [blame]980</ul>
981
Daniel Veillardd5f97f82000-09-17 16:38:14 +0000[diff] [blame]982<h3>2.2.0: July 14 2000</h3>
Daniel Veillard94e90602000-07-17 14:38:19 +0000[diff] [blame]983<ul>
984 <li>applied a lot of portability fixes</li>
985 <li>better encoding support/cleanup and saving (content is now always
986 encoded in UTF-8)</li>
987 <li>the HTML parser now correctly handles encodings</li>
988 <li>added xmlHasProp()</li>
989 <li>fixed a serious problem with &amp;#38;</li>
990 <li>propagated the fix to FTP client</li>
991 <li>cleanup, bugfixes, etc ...</li>
992 <li>Added a page about <a href="encoding.html">libxml Internationalization
993 support</a></li>
994</ul>
995
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]996<h3>1.8.9: July 9 2000</h3>
997<ul>
998 <li>fixed the spec the RPMs should be better</li>
999 <li>fixed a serious bug in the FTP implementation, released 1.8.9 to solve
1000 rpmfind users problem</li>
1001</ul>
1002
Daniel Veillard6388e172000-07-03 16:07:19 +0000[diff] [blame]1003<h3>2.1.1: July 1 2000</h3>
1004<ul>
1005 <li>fixes a couple of bugs in the 2.1.0 packaging</li>
1006 <li>improvements on the HTML parser</li>
1007</ul>
1008
Daniel Veillard3f6f7f62000-06-30 17:58:25 +0000[diff] [blame]1009<h3>2.1.0 and 1.8.8: June 29 2000</h3>
1010<ul>
1011 <li>1.8.8 is mostly a comodity package for upgrading to libxml2 accoding to
1012 <a href="upgrade.html">new instructions</a>. It fixes a nasty problem
1013 about &amp;#38; charref parsing</li>
1014 <li>2.1.0 also ease the upgrade from libxml v1 to the recent version. it
1015 also contains numerous fixes and enhancements:
1016 <ul>
1017 <li>added xmlStopParser() to stop parsing</li>
1018 <li>improved a lot parsing speed when there is large CDATA blocs</li>
1019 <li>includes XPath patches provided by Picdar Technology</li>
1020 <li>tried to fix as much as possible DtD validation and namespace
1021 related problems</li>
1022 <li>output to a given encoding has been added/tested</li>
1023 <li>lot of various fixes</li>
1024 </ul>
1025 </li>
1026</ul>
1027
Daniel Veillarde0aed302000-04-16 08:52:20 +0000[diff] [blame]1028<h3>2.0.0: Apr 12 2000</h3>
Daniel Veillard361d8452000-04-03 19:48:13 +0000[diff] [blame]1029<ul>
1030 <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]1031 idea to check the 1.x to 2.x upgrade instructions. NOTE: while initally
1032 scheduled for Apr 3 the relase occured only on Apr 12 due to massive
1033 workload.</li>
Daniel Veillard361d8452000-04-03 19:48:13 +0000[diff] [blame]1034 <li>The include are now located under $prefix/include/libxml (instead of
Daniel Veillarde0aed302000-04-16 08:52:20 +0000[diff] [blame]1035 $prefix/include/gnome-xml), they also are referenced by
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]1036 <pre>#include &lt;libxml/xxx.h&gt;</pre>
Daniel Veillarde0aed302000-04-16 08:52:20 +0000[diff] [blame]1037 <p>instead of</p>
Daniel Veillard361d8452000-04-03 19:48:13 +0000[diff] [blame]1038 <pre>#include "xxx.h"</pre>
1039 </li>
Daniel Veillard8f621982000-03-20 13:07:15 +0000[diff] [blame]1040 <li>a new URI module for parsing URIs and following strictly RFC 2396</li>
1041 <li>the memory allocation routines used by libxml can now be overloaded
1042 dynamically by using xmlMemSetup()</li>
Daniel Veillard361d8452000-04-03 19:48:13 +0000[diff] [blame]1043 <li>The previously CVS only tool tester has been renamed
1044 <strong>xmllint</strong> and is now installed as part of the libxml2
1045 package</li>
Daniel Veillarde0aed302000-04-16 08:52:20 +0000[diff] [blame]1046 <li>The I/O interface has been revamped. There is now ways to plug in
1047 specific I/O modules, either at the URI scheme detection level using
1048 xmlRegisterInputCallbacks() or by passing I/O functions when creating a
1049 parser context using xmlCreateIOParserCtxt()</li>
1050 <li>there is a C preprocessor macro LIBXML_VERSION providing the version
1051 number of the libxml module in use</li>
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]1052 <li>a number of optional features of libxml can now be excluded at
1053 configure time (FTP/HTTP/HTML/XPath/Debug)</li>
Daniel Veillardedfb29b2000-03-14 19:59:05 +0000[diff] [blame]1054</ul>
1055
1056<h3>2.0.0beta: Mar 14 2000</h3>
1057<ul>
1058 <li>This is a first Beta release of libxml version 2</li>
Daniel Veillarde356c282001-03-10 12:32:04 +0000[diff] [blame]1059 <li>It's available only from<a href="ftp://xmlsoft.org/">xmlsoft.org
1060 FTP</a>, it's packaged as libxml2-2.0.0beta and available as tar and
1061 RPMs</li>
Daniel Veillardedfb29b2000-03-14 19:59:05 +0000[diff] [blame]1062 <li>This version is now the head in the Gnome CVS base, the old one is
1063 available under the tag LIB_XML_1_X</li>
1064 <li>This includes a very large set of changes. Froma programmatic point of
1065 view applications should not have to be modified too much, check the <a
1066 href="upgrade.html">upgrade page</a></li>
1067 <li>Some interfaces may changes (especially a bit about encoding).</li>
1068 <li>the updates includes:
Daniel Veillard6c8b1172000-03-01 00:40:41 +0000[diff] [blame]1069 <ul>
Daniel Veillardedfb29b2000-03-14 19:59:05 +0000[diff] [blame]1070 <li>fix I18N support. ISO-Latin-x/UTF-8/UTF-16 (nearly) seems correctly
1071 handled now</li>
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]1072 <li>Better handling of entities, especially well formedness checking
1073 and proper PEref extensions in external subsets</li>
Daniel Veillard6c8b1172000-03-01 00:40:41 +0000[diff] [blame]1074 <li>DTD conditional sections</li>
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]1075 <li>Validation now correcly handle entities content</li>
Daniel Veillard6c8b1172000-03-01 00:40:41 +0000[diff] [blame]1076 <li><a href="http://rpmfind.net/tools/gdome/messages/0039.html">change
1077 structures to accomodate DOM</a></li>
Daniel Veillard6c8b1172000-03-01 00:40:41 +0000[diff] [blame]1078 </ul>
1079 </li>
Daniel Veillardedfb29b2000-03-14 19:59:05 +0000[diff] [blame]1080 <li>Serious progress were made toward compliance, <a
1081 href="conf/result.html">here are the result of the test</a> against the
1082 OASIS testsuite (except the japanese tests since I don't support that
1083 encoding yet). This URL is rebuilt every couple of hours using the CVS
1084 head version.</li>
Daniel Veillarde41f2b72000-01-30 20:00:07 +0000[diff] [blame]1085</ul>
1086
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]1087<h3>1.8.7: Mar 6 2000</h3>
1088<ul>
1089 <li>This is a bug fix release:</li>
1090 <li>It is possible to disable the ignorable blanks heuristic used by
1091 libxml-1.x, a new function xmlKeepBlanksDefault(0) will allow this. Note
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]1092 that for adherence to XML spec, this behaviour will be disabled by
1093 default in 2.x . The same function will allow to keep compatibility for
1094 old code.</li>
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]1095 <li>Blanks in &lt;a&gt; &lt;/a&gt; constructs are not ignored anymore,
1096 avoiding heuristic is really the Right Way :-\</li>
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]1097 <li>The unchecked use of snprintf which was breaking libxml-1.8.6
1098 compilation on some platforms has been fixed</li>
1099 <li>nanoftp.c nanohttp.c: Fixed '#' and '?' stripping when processing
1100 URIs</li>
1101</ul>
1102
Daniel Veillarde41f2b72000-01-30 20:00:07 +0000[diff] [blame]1103<h3>1.8.6: Jan 31 2000</h3>
1104<ul>
1105 <li>added a nanoFTP transport module, debugged until the new version of <a
1106 href="http://rpmfind.net/linux/rpm2html/rpmfind.html">rpmfind</a> can use
1107 it without troubles</li>
Daniel Veillardda07c342000-01-25 18:31:22 +0000[diff] [blame]1108</ul>
1109
1110<h3>1.8.5: Jan 21 2000</h3>
1111<ul>
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]1112 <li>adding APIs to parse a well balanced chunk of XML (production <a
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]1113 href="http://www.w3.org/TR/REC-xml#NT-content">[43] content</a> of the
1114 XML spec)</li>
Daniel Veillard461a66c2000-01-18 18:01:01 +0000[diff] [blame]1115 <li>fixed a hideous bug in xmlGetProp pointed by Rune.Djurhuus@fast.no</li>
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]1116 <li>Jody Goldberg &lt;jgoldberg@home.com&gt; provided another patch trying
1117 to solve the zlib checks problems</li>
Daniel Veillard461a66c2000-01-18 18:01:01 +0000[diff] [blame]1118 <li>The current state in gnome CVS base is expected to ship as 1.8.5 with
1119 gnumeric soon</li>
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]1120</ul>
1121
1122<h3>1.8.4: Jan 13 2000</h3>
1123<ul>
1124 <li>bug fixes, reintroduced xmlNewGlobalNs(), fixed xmlNewNs()</li>
1125 <li>all exit() call should have been removed from libxml</li>
1126 <li>fixed a problem with INCLUDE_WINSOCK on WIN32 platform</li>
1127 <li>added newDocFragment()</li>
Daniel Veillardf84f71f2000-01-05 19:54:23 +0000[diff] [blame]1128</ul>
1129
1130<h3>1.8.3: Jan 5 2000</h3>
1131<ul>
1132 <li>a Push interface for the XML and HTML parsers</li>
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]1133 <li>a shell-like interface to the document tree (try tester --shell :-)</li>
Daniel Veillarddbfd6411999-12-28 16:35:14 +0000[diff] [blame]1134 <li>lots of bug fixes and improvement added over XMas hollidays</li>
Daniel Veillard437b87b2000-01-03 17:30:46 +0000[diff] [blame]1135 <li>fixed the DTD parsing code to work with the xhtml DTD</li>
Daniel Veillardf84f71f2000-01-05 19:54:23 +0000[diff] [blame]1136 <li>added xmlRemoveProp(), xmlRemoveID() and xmlRemoveRef()</li>
1137 <li>Fixed bugs in xmlNewNs()</li>
Daniel Veillard437b87b2000-01-03 17:30:46 +0000[diff] [blame]1138 <li>External entity loading code has been revamped, now it uses
Daniel Veillardf84f71f2000-01-05 19:54:23 +0000[diff] [blame]1139 xmlLoadExternalEntity(), some fix on entities processing were added</li>
Daniel Veillard437b87b2000-01-03 17:30:46 +0000[diff] [blame]1140 <li>cleaned up WIN32 includes of socket stuff</li>
Daniel Veillard5cb5ab81999-12-21 15:35:29 +0000[diff] [blame]1141</ul>
1142
1143<h3>1.8.2: Dec 21 1999</h3>
1144<ul>
Daniel Veillardb24054a1999-12-18 15:32:46 +0000[diff] [blame]1145 <li>I got another problem with includes and C++, I hope this issue is fixed
1146 for good this time</li>
Daniel Veillard5cb5ab81999-12-21 15:35:29 +0000[diff] [blame]1147 <li>Added a few tree modification functions: xmlReplaceNode,
1148 xmlAddPrevSibling, xmlAddNextSibling, xmlNodeSetName and
1149 xmlDocSetRootElement</li>
1150 <li>Tried to improve the HTML output with help from <a
1151 href="mailto:clahey@umich.edu">Chris Lahey</a></li>
Daniel Veillarde4e51311999-12-18 15:32:46 +0000[diff] [blame]1152</ul>
Daniel Veillardb24054a1999-12-18 15:32:46 +0000[diff] [blame]1153
Daniel Veillarde4e51311999-12-18 15:32:46 +0000[diff] [blame]1154<h3>1.8.1: Dec 18 1999</h3>
1155<ul>
1156 <li>various patches to avoid troubles when using libxml with C++ compilers
1157 the "namespace" keyword and C escaping in include files</li>
1158 <li>a problem in one of the core macros IS_CHAR was corrected</li>
1159 <li>fixed a bug introduced in 1.8.0 breaking default namespace processing,
1160 and more specifically the Dia application</li>
Daniel Veillard944b5ff1999-12-15 19:08:24 +0000[diff] [blame]1161 <li>fixed a posteriori validation (validation after parsing, or by using a
1162 Dtd not specified in the original document)</li>
Daniel Veillardb24054a1999-12-18 15:32:46 +0000[diff] [blame]1163 <li>fixed a bug in</li>
Daniel Veillard10a2c651999-12-12 13:03:50 +0000[diff] [blame]1164</ul>
1165
1166<h3>1.8.0: Dec 12 1999</h3>
1167<ul>
1168 <li>cleanup, especially memory wise</li>
1169 <li>the parser should be more reliable, especially the HTML one, it should
1170 not crash, whatever the input !</li>
1171 <li>Integrated various patches, especially a speedup improvement for large
1172 dataset from <a href="mailto:cnygard@bellatlantic.net">Carl Nygard</a>,
1173 configure with --with-buffers to enable them.</li>
1174 <li>attribute normalization, oops should have been added long ago !</li>
1175 <li>attributes defaulted from Dtds should be available, xmlSetProp() now
1176 does entities escapting by default.</li>
Daniel Veillard4c3a2031999-11-19 17:46:26 +0000[diff] [blame]1177</ul>
Daniel Veillard35008381999-10-25 13:15:52 +0000[diff] [blame]1178
1179<h3>1.7.4: Oct 25 1999</h3>
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]1180<ul>
Daniel Veillard35008381999-10-25 13:15:52 +0000[diff] [blame]1181 <li>Lots of HTML improvement</li>
1182 <li>Fixed some errors when saving both XML and HTML</li>
1183 <li>More examples, the regression tests should now look clean</li>
1184 <li>Fixed a bug with contiguous charref</li>
1185</ul>
1186
1187<h3>1.7.3: Sep 29 1999</h3>
1188<ul>
1189 <li>portability problems fixed</li>
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]1190 <li>snprintf was used unconditionnally, leading to link problems on system
Daniel Veillard35008381999-10-25 13:15:52 +0000[diff] [blame]1191 were it's not available, fixed</li>
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]1192</ul>
1193
1194<h3>1.7.1: Sep 24 1999</h3>
1195<ul>
1196 <li>The basic type for strings manipulated by libxml has been renamed in
1197 1.7.1 from <strong>CHAR</strong> to <strong>xmlChar</strong>. The reason
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]1198 is that CHAR was conflicting with a predefined type on Windows. However
1199 on non WIN32 environment, compatibility is provided by the way of a
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]1200 <strong>#define </strong>.</li>
1201 <li>Changed another error : the use of a structure field called errno, and
1202 leading to troubles on platforms where it's a macro</li>
1203</ul>
1204
1205<h3>1.7.0: sep 23 1999</h3>
1206<ul>
1207 <li>Added the ability to fetch remote DTD or parsed entities, see the <a
Daniel Veillard9cb5ff42001-01-29 08:22:21 +0000[diff] [blame]1208 href="html/libxml-nanohttp.html">nanohttp</a> module.</li>
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]1209 <li>Added an errno to report errors by another mean than a simple printf
1210 like callback</li>
1211 <li>Finished ID/IDREF support and checking when validation</li>
1212 <li>Serious memory leaks fixed (there is now a <a
Daniel Veillard9cb5ff42001-01-29 08:22:21 +0000[diff] [blame]1213 href="html/libxml-xmlmemory.html">memory wrapper</a> module)</li>
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]1214 <li>Improvement of <a href="http://www.w3.org/TR/xpath">XPath</a>
1215 implementation</li>
1216 <li>Added an HTML parser front-end</li>
1217</ul>
1218
1219<h2><a name="XML">XML</a></h2>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]1220
Daniel Veillard402e8c82000-02-29 22:57:47 +0000[diff] [blame]1221<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]1222markup-based structured documents. Here is <a name="example">an example XML
1223document</a>:</p>
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]1224<pre>&lt;?xml version="1.0"?&gt;
1225&lt;EXAMPLE prop1="gnome is great" prop2="&amp;amp; linux too"&gt;
1226 &lt;head&gt;
1227 &lt;title&gt;Welcome to Gnome&lt;/title&gt;
1228 &lt;/head&gt;
1229 &lt;chapter&gt;
1230 &lt;title&gt;The Linux adventure&lt;/title&gt;
1231 &lt;p&gt;bla bla bla ...&lt;/p&gt;
1232 &lt;image href="linus.gif"/&gt;
1233 &lt;p&gt;...&lt;/p&gt;
1234 &lt;/chapter&gt;
1235&lt;/EXAMPLE&gt;</pre>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]1236
Daniel Veillard402e8c82000-02-29 22:57:47 +0000[diff] [blame]1237<p>The first line specifies that it's an XML document and gives useful
1238information about its encoding. Then the document is a text format whose
1239structure is specified by tags between brackets. <strong>Each tag opened has
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]1240to be closed</strong>. XML is pedantic about this. However, if a tag is empty
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]1241(no content), a single tag can serve as both the opening and closing tag if
1242it ends with <code>/&gt;</code> rather than with <code>&gt;</code>. Note
1243that, for example, the image tag has no content (just an attribute) and is
1244closed by ending the tag with <code>/&gt;</code>.</p>
Daniel Veillardccb09631998-10-27 06:21:04 +0000[diff] [blame]1245
Daniel Veillard402e8c82000-02-29 22:57:47 +0000[diff] [blame]1246<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]1247structured document maintenance (where it follows the steps of SGML) to
1248simple data encoding mechanisms like configuration file formatting (glade),
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]1249spreadsheets (gnumeric), or even shorter lived documents such as WebDAV where
1250it is used to encode remote calls between a client and a server.</p>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]1251
Daniel Veillard82687162001-01-22 15:32:01 +0000[diff] [blame]1252<h2><a name="XSLT">XSLT</a></h2>
1253
Daniel Veillard6e6a6cc2001-02-15 15:55:44 +0000[diff] [blame]1254<p>Check <a href="http://xmlsoft.org/XSLT">the separate libxslt page</a></p>
1255
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]1256<p><a href="http://www.w3.org/TR/xslt">XSL Transformations</a>, is a
1257language for transforming XML documents into other XML documents (or
1258HTML/textual output).</p>
Daniel Veillard82687162001-01-22 15:32:01 +0000[diff] [blame]1259
1260<p>A separate library called libxslt is being built on top of libxml2. This
1261module "libxslt" can be found in the Gnome CVS base too.</p>
1262
Daniel Veillard383b1472001-01-23 11:39:52 +0000[diff] [blame]1263<p>You can check the <a
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]1264href="http://cvs.gnome.org/lxr/source/libxslt/FEATURES">features</a>
1265supported and the progresses on the <a
Daniel Veillard82687162001-01-22 15:32:01 +0000[diff] [blame]1266href="http://cvs.gnome.org/lxr/source/libxslt/ChangeLog">Changelog</a></p>
1267
Daniel Veillardb8cfbd12001-10-25 10:53:28 +0000[diff] [blame]1268<h2><a name="architecture">libxml architecture</a></h2>
Daniel Veillard4540be42000-08-19 16:40:28 +0000[diff] [blame]1269
Daniel Veillardec70e912001-02-26 20:10:45 +0000[diff] [blame]1270<p>Libxml is made of multiple components; some of them are optional, and most
1271of the block interfaces are public. The main components are:</p>
Daniel Veillard4540be42000-08-19 16:40:28 +0000[diff] [blame]1272<ul>
1273 <li>an Input/Output layer</li>
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]1274 <li>FTP and HTTP client layers (optional)</li>
Daniel Veillard4540be42000-08-19 16:40:28 +0000[diff] [blame]1275 <li>an Internationalization layer managing the encodings support</li>
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]1276 <li>a URI module</li>
Daniel Veillard4540be42000-08-19 16:40:28 +0000[diff] [blame]1277 <li>the XML parser and its basic SAX interface</li>
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]1278 <li>an HTML parser using the same SAX interface (optional)</li>
Daniel Veillard4540be42000-08-19 16:40:28 +0000[diff] [blame]1279 <li>a SAX tree module to build an in-memory DOM representation</li>
1280 <li>a tree module to manipulate the DOM representation</li>
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]1281 <li>a validation module using the DOM representation (optional)</li>
Daniel Veillard4540be42000-08-19 16:40:28 +0000[diff] [blame]1282 <li>an XPath module for global lookup in a DOM representation
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]1283 (optional)</li>
1284 <li>a debug module (optional)</li>
Daniel Veillard4540be42000-08-19 16:40:28 +0000[diff] [blame]1285</ul>
1286
1287<p>Graphically this gives the following:</p>
1288
1289<p><img src="libxml.gif" alt="a graphical view of the various"></p>
1290
1291<p></p>
1292
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]1293<h2><a name="tree">The tree output</a></h2>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]1294
1295<p>The parser returns a tree built during the document analysis. The value
Daniel Veillard402e8c82000-02-29 22:57:47 +0000[diff] [blame]1296returned is an <strong>xmlDocPtr</strong> (i.e., a pointer to an
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]1297<strong>xmlDoc</strong> structure). This structure contains information such
Daniel Veillard306be992000-07-03 12:38:45 +0000[diff] [blame]1298as the file name, the document type, and a <strong>children</strong> pointer
1299which is the root of the document (or more exactly the first child under the
1300root which is the document). The tree is made of <strong>xmlNode</strong>s,
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]1301chained in double-linked lists of siblings and with a children&lt;-&gt;parent
Daniel Veillard306be992000-07-03 12:38:45 +0000[diff] [blame]1302relationship. An xmlNode can also carry properties (a chain of xmlAttr
1303structures). An attribute may have a value which is a list of TEXT or
1304ENTITY_REF nodes.</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]1305
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]1306<p>Here is an example (erroneous with respect to the XML spec since there
1307should be only one ELEMENT under the root):</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]1308
1309<p><img src="structure.gif" alt=" structure.gif "></p>
1310
1311<p>In the source package there is a small program (not installed by default)
Daniel Veillard361d8452000-04-03 19:48:13 +0000[diff] [blame]1312called <strong>xmllint</strong> which parses XML files given as argument and
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]1313prints them back as parsed. This is useful for detecting errors both in XML
1314code and in the XML parser itself. It has an option <strong>--debug</strong>
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]1315which prints the actual in-memory structure of the document; here is the
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]1316result with the <a href="#example">example</a> given before:</p>
Daniel Veillard10c6a8f1998-10-28 01:00:12 +0000[diff] [blame]1317<pre>DOCUMENT
1318version=1.0
1319standalone=true
1320 ELEMENT EXAMPLE
1321 ATTRIBUTE prop1
1322 TEXT
1323 content=gnome is great
1324 ATTRIBUTE prop2
1325 ENTITY_REF
1326 TEXT
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]1327 content= linux too
Daniel Veillard402e8c82000-02-29 22:57:47 +0000[diff] [blame]1328 ELEMENT head
Daniel Veillard10c6a8f1998-10-28 01:00:12 +0000[diff] [blame]1329 ELEMENT title
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]1330 TEXT
1331 content=Welcome to Gnome
Daniel Veillard10c6a8f1998-10-28 01:00:12 +0000[diff] [blame]1332 ELEMENT chapter
1333 ELEMENT title
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]1334 TEXT
1335 content=The Linux adventure
Daniel Veillard10c6a8f1998-10-28 01:00:12 +0000[diff] [blame]1336 ELEMENT p
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]1337 TEXT
1338 content=bla bla bla ...
Daniel Veillard10c6a8f1998-10-28 01:00:12 +0000[diff] [blame]1339 ELEMENT image
1340 ATTRIBUTE href
1341 TEXT
1342 content=linus.gif
1343 ELEMENT p
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]1344 TEXT
1345 content=...</pre>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]1346
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]1347<p>This should be useful for learning the internal representation model.</p>
Daniel Veillardccb09631998-10-27 06:21:04 +0000[diff] [blame]1348
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]1349<h2><a name="interface">The SAX interface</a></h2>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]1350
Daniel Veillard402e8c82000-02-29 22:57:47 +0000[diff] [blame]1351<p>Sometimes the DOM tree output is just too large to fit reasonably into
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]1352memory. 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]1353loaded using libxml), it's better to use the SAX interface of libxml. SAX is
1354a <strong>callback-based interface</strong> to the parser. Before parsing,
1355the application layer registers a customized set of callbacks which are
1356called by the library as it progresses through the XML input.</p>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]1357
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]1358<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]1359libxml, see the <a
1360href="http://www.daa.com.au/~james/gnome/xml-sax/xml-sax.html">nice
1361documentation</a>.written by <a href="mailto:james@daa.com.au">James
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]1362Henstridge</a>.</p>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]1363
1364<p>You can debug the SAX behaviour by using the <strong>testSAX</strong>
1365program located in the gnome-xml module (it's usually not shipped in the
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]1366binary packages of libxml, but you can find it in the tar source
Daniel Veillard402e8c82000-02-29 22:57:47 +0000[diff] [blame]1367distribution). Here is the sequence of callbacks that would be reported by
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]1368testSAX when parsing the example XML document shown earlier:</p>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]1369<pre>SAX.setDocumentLocator()
1370SAX.startDocument()
1371SAX.getEntity(amp)
1372SAX.startElement(EXAMPLE, prop1='gnome is great', prop2='&amp;amp; linux too')
1373SAX.characters( , 3)
1374SAX.startElement(head)
1375SAX.characters( , 4)
1376SAX.startElement(title)
1377SAX.characters(Welcome to Gnome, 16)
1378SAX.endElement(title)
1379SAX.characters( , 3)
1380SAX.endElement(head)
1381SAX.characters( , 3)
1382SAX.startElement(chapter)
1383SAX.characters( , 4)
1384SAX.startElement(title)
1385SAX.characters(The Linux adventure, 19)
1386SAX.endElement(title)
1387SAX.characters( , 4)
1388SAX.startElement(p)
1389SAX.characters(bla bla bla ..., 15)
1390SAX.endElement(p)
1391SAX.characters( , 4)
1392SAX.startElement(image, href='linus.gif')
1393SAX.endElement(image)
1394SAX.characters( , 4)
1395SAX.startElement(p)
1396SAX.characters(..., 3)
1397SAX.endElement(p)
1398SAX.characters( , 3)
1399SAX.endElement(chapter)
1400SAX.characters( , 1)
1401SAX.endElement(EXAMPLE)
1402SAX.endDocument()</pre>
1403
Daniel Veillardec70e912001-02-26 20:10:45 +0000[diff] [blame]1404<p>Most of the other interfaces of libxml are based on the DOM tree-building
1405facility, so nearly everything up to the end of this document presupposes the
1406use of the standard DOM tree build. Note that the DOM tree itself is built by
1407a set of registered default callbacks, without internal specific
1408interface.</p>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]1409
Daniel Veillardb8cfbd12001-10-25 10:53:28 +0000[diff] [blame]1410<h2><a name="Validation">Validation &amp; DTDs</a></h2>
1411
1412<p>Table of Content:</p>
1413<ol>
1414 <li><a href="#General5">General overview</a></li>
1415 <li><a href="#definition">The definition</a></li>
1416 <li><a href="#Simple">Simple rules</a>
1417 <ol>
Daniel Veillard9c466822001-10-25 12:03:39 +0000[diff] [blame]1418 <li><a href="#reference">How to reference a DTD from a document</a></li>
Daniel Veillardb8cfbd12001-10-25 10:53:28 +0000[diff] [blame]1419 <li><a href="#Declaring">Declaring elements</a></li>
1420 <li><a href="#Declaring1">Declaring attributes</a></li>
1421 </ol>
1422 </li>
1423 <li><a href="#Some">Some examples</a></li>
1424 <li><a href="#validate">How to validate</a></li>
1425 <li><a href="#Other">Other resources</a></li>
1426</ol>
1427
1428<h3><a name="General5">General overview</a></h3>
1429
1430<p>Well what is validation and what is a DTD ?</p>
1431
1432<p>DTD is the acronym for Document Type Definition. This is a description of
1433the content for a familly of XML files. This is part of the XML 1.0
1434specification, and alows to describe and check that a given document instance
1435conforms to a set of rules detailing its structure and content.</p>
1436
1437<p>Validation is the process of checking a document against a DTD (more
1438generally against a set of construction rules).</p>
1439
1440<p>The validation process and building DTDs are the two most difficult parts
1441of the XML life cycle. Briefly a DTD defines all the possibles element to be
1442found within your document, what is the formal shape of your document tree
1443(by defining the allowed content of an element, either text, a regular
1444expression for the allowed list of children, or mixed content i.e. both text
1445and children). The DTD also defines the allowed attributes for all elements
1446and the types of the attributes.</p>
1447
1448<h3><a name="definition1">The definition</a></h3>
1449
1450<p>The <a href="http://www.w3.org/TR/REC-xml">W3C XML Recommendation</a> (<a
1451href="http://www.xml.com/axml/axml.html">Tim Bray's annotated version of
1452Rev1</a>):</p>
1453<ul>
1454 <li><a href="http://www.w3.org/TR/REC-xml#elemdecls">Declaring
1455 elements</a></li>
1456 <li><a href="http://www.w3.org/TR/REC-xml#attdecls">Declaring
1457 attributes</a></li>
1458</ul>
1459
1460<p>(unfortunately) all this is inherited from the SGML world, the syntax is
1461ancient...</p>
1462
1463<h3><a name="Simple1">Simple rules</a></h3>
1464
1465<p>Writing DTD can be done in multiple ways, the rules to build them if you
1466need something fixed or something which can evolve over time can be radically
1467different. Really complex DTD like Docbook ones are flexible but quite harder
1468to design. I will just focuse on DTDs for a formats with a fixed simple
1469structure. It is just a set of basic rules, and definitely not exhaustive nor
1470useable for complex DTD design.</p>
1471
1472<h4><a name="reference1">How to reference a DTD from a document</a>:</h4>
1473
1474<p>Assuming the top element of the document is <code>spec</code> and the dtd
1475is placed in the file <code>mydtd</code> in the subdirectory
1476<code>dtds</code> of the directory from where the document were loaded:</p>
1477
1478<p><code>&lt;!DOCTYPE spec SYSTEM "dtds/mydtd"&gt;</code></p>
1479
1480<p>Notes:</p>
1481<ul>
1482 <li>the system string is actually an URI-Reference (as defined in <a
1483 href="http://www.ietf.org/rfc/rfc2396.txt">RFC 2396</a>) so you can use a
1484 full URL string indicating the location of your DTD on the Web, this is a
1485 really good thing to do if you want others to validate your document</li>
1486 <li>it is also possible to associate a <code>PUBLIC</code> identifier (a
1487 magic string) so that the DTd is looked up in catalogs on the client side
1488 without having to locate it on the web</li>
1489 <li>a dtd contains a set of elements and attributes declarations, but they
1490 don't define what the root of the document should be. This is explicitely
1491 told to the parser/validator as the first element of the
1492 <code>DOCTYPE</code> declaration.</li>
1493</ul>
1494
1495<h4><a name="Declaring2">Declaring elements</a>:</h4>
1496
1497<p>The following declares an element <code>spec</code>:</p>
1498
1499<p><code>&lt;!ELEMENT spec (front, body, back?)&gt;</code></p>
1500
1501<p>it also expresses that the spec element contains one <code>front</code>,
1502one <code>body</code> and one optionnal <code>back</code> children elements
1503in this order. The declaration of one element of the structure and its
1504content are done in a single declaration. Similary the following declares
1505<code>div1</code> elements:</p>
1506
1507<p><code>&lt;!ELEMENT div1 (head, (p | list | note)*, div2*)&gt;</code></p>
1508
1509<p>means div1 contains one <code>head</code> then a series of optional
1510<code>p</code>, <code>list</code>s and <code>note</code>s and then an
1511optional <code>div2</code>. And last but not least an element can contain
1512text:</p>
1513
1514<p><code>&lt;!ELEMENT b (#PCDATA)&gt;</code></p>
1515
1516<p><code>b</code> contains text or being of mixed content (text and elements
1517in no particular order):</p>
1518
1519<p><code>&lt;!ELEMENT p (#PCDATA|a|ul|b|i|em)*&gt;</code></p>
1520
1521<p><code>p </code>can contain text or <code>a</code>, <code>ul</code>,
1522<code>b</code>, <code>i </code>or <code>em</code> elements in no particular
1523order.</p>
1524
1525<h4><a name="Declaring1">Declaring attributes</a>:</h4>
1526
1527<p>again the attributes declaration includes their content definition:</p>
1528
1529<p><code>&lt;!ATTLIST termdef name CDATA #IMPLIED&gt;</code></p>
1530
1531<p>means that the element <code>termdef</code> can have a <code>name</code>
1532attribute containing text (<code>CDATA</code>) and which is optionnal
1533(<code>#IMPLIED</code>). The attribute value can also be defined within a
1534set:</p>
1535
1536<p><code>&lt;!ATTLIST list type (bullets|ordered|glossary)
1537"ordered"&gt;</code></p>
1538
1539<p>means <code>list</code> element have a <code>type</code> attribute with 3
1540allowed values "bullets", "ordered" or "glossary" and which default to
1541"ordered" if the attribute is not explicitely specified.</p>
1542
1543<p>The content type of an attribute can be text (<code>CDATA</code>),
1544anchor/reference/references
1545(<code>ID</code>/<code>IDREF</code>/<code>IDREFS</code>), entity(ies)
1546(<code>ENTITY</code>/<code>ENTITIES</code>) or name(s)
1547(<code>NMTOKEN</code>/<code>NMTOKENS</code>). The following defines that a
1548<code>chapter</code> element can have an optional <code>id</code> attribute
1549of type <code>ID</code>, usable for reference from attribute of type
1550IDREF:</p>
1551
1552<p><code>&lt;!ATTLIST chapter id ID #IMPLIED&gt;</code></p>
1553
1554<p>The last value of an attribute definition can be <code>#REQUIRED
1555</code>meaning that the attribute has to be given, <code>#IMPLIED</code>
1556meaning that it is optional, or the default value (possibly prefixed by
1557<code>#FIXED</code> if it is the only allowed).</p>
1558
1559<p>Notes:</p>
1560<ul>
1561 <li>usually the attributes pertaining to a given element are declared in a
1562 single expression, but it is just a convention adopted by a lot of DTD
1563 writers:
1564 <pre>&lt;!ATTLIST termdef
1565 id ID #REQUIRED
1566 name CDATA #IMPLIED&gt;</pre>
1567 <p>The previous construct defines both <code>id</code> and
1568 <code>name</code> attributes for the element <code>termdef</code></p>
1569 </li>
1570</ul>
1571
1572<h3><a name="Some1">Some examples</a></h3>
1573
1574<p>The directory <code>test/valid/dtds/</code> in the libxml distribution
1575contains some complex DTD examples. The <code>test/valid/dia.xml</code>
1576example shows an XML file where the simple DTD is directly included within
1577the document.</p>
1578
1579<h3><a name="validate1">How to validate</a></h3>
1580
1581<p>The simplest is to use the xmllint program comming with libxml. The
1582<code>--valid</code> option turn on validation of the files given as input,
1583for example the following validates a copy of the first revision of the XML
15841.0 specification:</p>
1585
1586<p><code>xmllint --valid --noout test/valid/REC-xml-19980210.xml</code></p>
1587
1588<p>the -- noout is used to not output the resulting tree.</p>
1589
1590<p>The <code>--dtdvalid dtd</code> allows to validate the document(s) against
1591a given DTD.</p>
1592
1593<p>Libxml exports an API to handle DTDs and validation, check the <a
1594href="http://xmlsoft.org/html/libxml-valid.html">associated
1595description</a>.</p>
1596
1597<h3><a name="Other1">Other resources</a></h3>
1598
1599<p>DTDs are as old as SGML. So there may be a number of examples on-line, I
1600will just list one for now, others pointers welcome:</p>
1601<ul>
1602 <li><a href="http://www.xml101.com:8081/dtd/">XML-101 DTD</a></li>
1603</ul>
1604
1605<p>I suggest looking at the examples found under test/valid/dtd and any of
1606the large number of books available on XML. The dia example in test/valid
1607should be both simple and complete enough to allow you to build your own.</p>
1608
1609<p></p>
1610
1611<h2><a name="Memory">Memory Management</a></h2>
1612
1613<p>Table of Content:</p>
1614<ol>
1615 <li><a href="#General3">General overview</a></li>
Daniel Veillard9c466822001-10-25 12:03:39 +0000[diff] [blame]1616 <li><a href="#setting">Setting libxml set of memory routines</a></li>
Daniel Veillardb8cfbd12001-10-25 10:53:28 +0000[diff] [blame]1617 <li><a href="#cleanup">Cleaning up after parsing</a></li>
1618 <li><a href="#Debugging">Debugging routines</a></li>
1619 <li><a href="#General4">General memory requirements</a></li>
1620</ol>
1621
1622<h3><a name="General3">General overview</a></h3>
1623
1624<p>The module <code><a
1625href="http://xmlsoft.org/html/libxml-xmlmemory.html">xmlmemory.h</a></code>
1626provides the interfaces to the libxml memory system:</p>
1627<ul>
1628 <li>libxml does not use the libc memory allocator directly but xmlFree(),
1629 xmlMalloc() and xmlRealloc()</li>
1630 <li>those routines can be reallocated to a specific set of routine, by
1631 default the libc ones i.e. free(), malloc() and realloc()</li>
1632 <li>the xmlmemory.c module includes a set of debugging routine</li>
1633</ul>
1634
1635<h3><a name="setting">Setting libxml set of memory routines</a></h3>
1636
1637<p>It is sometimes useful to not use the default memory allocator, either for
1638debugging, analysis or to implement a specific behaviour on memory management
1639(like on embedded systems). Two function calls are available to do so:</p>
1640<ul>
1641 <li><a href="http://xmlsoft.org/html/libxml-xmlmemory.html">xmlMemGet ()</a>
1642 which return the current set of functions in use by the parser</li>
1643 <li><a
1644 href="http://xmlsoft.org/html/libxml-xmlmemory.html">xmlMemSetup()</a>
1645 which allow to set up a new set of memory allocation functions</li>
1646</ul>
1647
1648<p>Of course a call to xmlMemSetup() should probably be done before calling
1649any other libxml routines (unless you are sure your allocations routines are
1650compatibles).</p>
1651
1652<h3><a name="cleanup">Cleaning up after parsing</a></h3>
1653
1654<p>Libxml is not stateless, there is a few set of memory structures needing
1655allocation before the parser is fully functionnal (some encoding structures
1656for example). This also mean that once parsing is finished there is a tiny
1657amount of memory (a few hundred bytes) which can be recollected if you don't
1658reuse the parser immediately:</p>
1659<ul>
1660 <li><a href="http://xmlsoft.org/html/libxml-parser.html">xmlCleanupParser
1661 ()</a>
1662 is a centralized routine to free the parsing states. Note that it won't
1663 deallocate any produced tree if any (use the xmlFreeDoc() and related
1664 routines for this).</li>
1665 <li><a href="http://xmlsoft.org/html/libxml-parser.html">xmlInitParser
1666 ()</a>
1667 is the dual routine allowing to preallocate the parsing state which can
1668 be useful for example to avoid initialization reentrancy problems when
1669 using libxml in multithreaded applications</li>
1670</ul>
1671
1672<p>Generally xmlCleanupParser() is safe, if needed the state will be rebuild
1673at the next invocation of parser routines, but be careful of the consequences
1674in multithreaded applications.</p>
1675
1676<h3><a name="Debugging">Debugging routines</a></h3>
1677
1678<p>When configured using --with-mem-debug flag (off by default), libxml uses
1679a set of memory allocation debugging routineskeeping track of all allocated
1680blocks and the location in the code where the routine was called. A couple of
1681other debugging routines allow to dump the memory allocated infos to a file
1682or call a specific routine when a given block number is allocated:</p>
1683<ul>
1684 <li><a
1685 href="http://xmlsoft.org/html/libxml-xmlmemory.html">xmlMallocLoc()</a>
1686 <a
1687 href="http://xmlsoft.org/html/libxml-xmlmemory.html">xmlReallocLoc()</a>
1688 and <a
1689 href="http://xmlsoft.org/html/libxml-xmlmemory.html">xmlMemStrdupLoc()</a>
1690 are the memory debugging replacement allocation routines</li>
1691 <li><a href="http://xmlsoft.org/html/libxml-xmlmemory.html">xmlMemoryDump
1692 ()</a>
1693 dumps all the informations about the allocated memory block lefts in the
1694 <code>.memdump</code> file</li>
1695</ul>
1696
1697<p>When developping libxml memory debug is enabled, the tests programs call
1698xmlMemoryDump () and the "make test" regression tests will check for any
1699memory leak during the full regression test sequence, this helps a lot
1700ensuring that libxml does not leak memory and bullet proof memory
1701allocations use (some libc implementations are known to be far too permissive
1702resulting in major portability problems!).</p>
1703
1704<p>If the .memdump reports a leak, it displays the allocation function and
1705also tries to give some informations about the content and structure of the
1706allocated blocks left. This is sufficient in most cases to find the culprit,
1707but not always. Assuming the allocation problem is reproductible, it is
1708possible to find more easilly:</p>
1709<ol>
1710 <li>write down the block number xxxx not allocated</li>
1711 <li>export the environement variable XML_MEM_BREAKPOINT=xxxx</li>
1712 <li>run the program under a debugger and set a breakpoint on
1713 xmlMallocBreakpoint() a specific function called when this precise block
1714 is allocated</li>
1715 <li>when the breakpoint is reached you can then do a fine analysis of the
1716 allocation an step to see the condition resulting in the missing
1717 deallocation.</li>
1718</ol>
1719
1720<p>I used to use a commercial tool to debug libxml memory problems but after
1721noticing that it was not detecting memory leaks that simple mechanism was
1722used and proved extremely efficient until now.</p>
1723
1724<h3><a name="General4">General memory requirements</a></h3>
1725
1726<p>How much libxml memory require ? It's hard to tell in average it depends
1727of a number of things:</p>
1728<ul>
1729 <li>the parser itself should work in a fixed amout of memory, except for
1730 information maintained about the stacks of names and entities locations.
1731 The I/O and encoding handlers will probably account for a few KBytes.
1732 This is true for both the XML and HTML parser (though the HTML parser
1733 need more state).</li>
1734 <li>If you are generating the DOM tree then memory requirements will grow
1735 nearly lineary with the size of the data. In general for a balanced
1736 textual document the internal memory requirement is about 4 times the
1737 size of the UTF8 serialization of this document (exmple the XML-1.0
1738 recommendation is a bit more of 150KBytes and takes 650KBytes of main
1739 memory when parsed). Validation will add a amount of memory required for
1740 maintaining the external Dtd state which should be linear with the
1741 complexity of the content model defined by the Dtd</li>
1742 <li>If you don't care about the advanced features of libxml like
1743 validation, DOM, XPath or XPointer, but really need to work fixed memory
1744 requirements, then the SAX interface should be used.</li>
1745</ul>
1746
1747<p></p>
1748
1749<h2><a name="Encodings">Encodings support</a></h2>
1750
1751<p>Table of Content:</p>
1752<ol>
1753 <li><a href="encoding.html#What">What does internationalization support
1754 mean ?</a></li>
1755 <li><a href="encoding.html#internal">The internal encoding, how and
1756 why</a></li>
1757 <li><a href="encoding.html#implemente">How is it implemented ?</a></li>
1758 <li><a href="encoding.html#Default">Default supported encodings</a></li>
1759 <li><a href="encoding.html#extend">How to extend the existing
1760 support</a></li>
1761</ol>
1762
1763<h3><a name="What">What does internationalization support mean ?</a></h3>
1764
1765<p>XML was designed from the start to allow the support of any character set
1766by using Unicode. Any conformant XML parser has to support the UTF-8 and
1767UTF-16 default encodings which can both express the full unicode ranges. UTF8
1768is a variable length encoding whose greatest point are to resuse the same
1769emcoding for ASCII and to save space for Western encodings, but it is a bit
1770more complex to handle in practice. UTF-16 use 2 bytes per characters (and
1771sometimes combines two pairs), it makes implementation easier, but looks a
1772bit overkill for Western languages encoding. Moreover the XML specification
1773allows document to be encoded in other encodings at the condition that they
1774are clearly labelled as such. For example the following is a wellformed XML
1775document encoded in ISO-8859 1 and using accentuated letter that we French
1776likes for both markup and content:</p>
1777<pre>&lt;?xml version="1.0" encoding="ISO-8859-1"?&gt;
1778&lt;très&gt;là&lt;/très&gt;</pre>
1779
1780<p>Having internationalization support in libxml means the foolowing:</p>
1781<ul>
1782 <li>the document is properly parsed</li>
1783 <li>informations about it's encoding are saved</li>
1784 <li>it can be modified</li>
1785 <li>it can be saved in its original encoding</li>
1786 <li>it can also be saved in another encoding supported by libxml (for
1787 example straight UTF8 or even an ASCII form)</li>
1788</ul>
1789
1790<p>Another very important point is that the whole libxml API, with the
1791exception of a few routines to read with a specific encoding or save to a
1792specific encoding, is completely agnostic about the original encoding of the
1793document.</p>
1794
1795<p>It should be noted too that the HTML parser embedded in libxml now obbey
1796the same rules too, the following document will be (as of 2.2.2) handled in
1797an internationalized fashion by libxml too:</p>
1798<pre>&lt;!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN"
1799 "http://www.w3.org/TR/REC-html40/loose.dtd"&gt;
1800&lt;html lang="fr"&gt;
1801&lt;head&gt;
1802 &lt;META HTTP-EQUIV="Content-Type" CONTENT="text/html; charset=ISO-8859-1"&gt;
1803&lt;/head&gt;
1804&lt;body&gt;
1805&lt;p&gt;W3C crée des standards pour le Web.&lt;/body&gt;
1806&lt;/html&gt;</pre>
1807
1808<h3><a name="internal">The internal encoding, how and why</a></h3>
1809
1810<p>One of the core decision was to force all documents to be converted to a
1811default internal encoding, and that encoding to be UTF-8, here are the
1812rationale for those choices:</p>
1813<ul>
1814 <li>keeping the native encoding in the internal form would force the libxml
1815 users (or the code associated) to be fully aware of the encoding of the
1816 original document, for examples when adding a text node to a document,
1817 the content would have to be provided in the document encoding, i.e. the
1818 client code would have to check it before hand, make sure it's conformant
1819 to the encoding, etc ... Very hard in practice, though in some specific
1820 cases this may make sense.</li>
1821 <li>the second decision was which encoding. From the XML spec only UTF8 and
1822 UTF16 really makes sense as being the two only encodings for which there
1823 is amndatory support. UCS-4 (32 bits fixed size encoding) could be
1824 considered an intelligent choice too since it's a direct Unicode mapping
1825 support. I selected UTF-8 on the basis of efficiency and compatibility
1826 with surrounding software:
1827 <ul>
1828 <li>UTF-8 while a bit more complex to convert from/to (i.e. slightly
1829 more costly to import and export CPU wise) is also far more compact
1830 than UTF-16 (and UCS-4) for a majority of the documents I see it used
1831 for right now (RPM RDF catalogs, advogato data, various configuration
1832 file formats, etc.) and the key point for today's computer
1833 architecture is efficient uses of caches. If one nearly double the
1834 memory requirement to store the same amount of data, this will trash
1835 caches (main memory/external caches/internal caches) and my take is
1836 that this harms the system far more than the CPU requirements needed
1837 for the conversion to UTF-8</li>
1838 <li>Most of libxml version 1 users were using it with straight ASCII
1839 most of the time, doing the conversion with an internal encoding
1840 requiring all their code to be rewritten was a serious show-stopper
1841 for using UTF-16 or UCS-4.</li>
1842 <li>UTF-8 is being used as the de-facto internal encoding standard for
1843 related code like the <a href="http://www.pango.org/">pango</a>
1844 upcoming Gnome text widget, and a lot of Unix code (yep another place
1845 where Unix programmer base takes a different approach from Microsoft
1846 - they are using UTF-16)</li>
1847 </ul>
1848 </li>
1849</ul>
1850
1851<p>What does this mean in practice for the libxml user:</p>
1852<ul>
1853 <li>xmlChar, the libxml data type is a byte, those bytes must be assembled
1854 as UTF-8 valid strings. The proper way to terminate an xmlChar * string
1855 is simply to append 0 byte, as usual.</li>
1856 <li>One just need to make sure that when using chars outside the ASCII set,
1857 the values has been properly converted to UTF-8</li>
1858</ul>
1859
1860<h3><a name="implemente">How is it implemented ?</a></h3>
1861
1862<p>Let's describe how all this works within libxml, basically the I18N
1863(internationalization) support get triggered only during I/O operation, i.e.
1864when reading a document or saving one. Let's look first at the reading
1865sequence:</p>
1866<ol>
1867 <li>when a document is processed, we usually don't know the encoding, a
1868 simple heuristic allows to detect UTF-18 and UCS-4 from whose where the
1869 ASCII range (0-0x7F) maps with ASCII</li>
1870 <li>the xml declaration if available is parsed, including the encoding
1871 declaration. At that point, if the autodetected encoding is different
1872 from the one declared a call to xmlSwitchEncoding() is issued.</li>
1873 <li>If there is no encoding declaration, then the input has to be in either
1874 UTF-8 or UTF-16, if it is not then at some point when processing the
1875 input, the converter/checker of UTF-8 form will raise an encoding error.
1876 You may end-up with a garbled document, or no document at all ! Example:
1877 <pre>~/XML -&gt; ./xmllint err.xml
1878err.xml:1: error: Input is not proper UTF-8, indicate encoding !
1879&lt;très&gt;là&lt;/très&gt;
1880 ^
1881err.xml:1: error: Bytes: 0xE8 0x73 0x3E 0x6C
1882&lt;très&gt;là&lt;/très&gt;
1883 ^</pre>
1884 </li>
1885 <li>xmlSwitchEncoding() does an encoding name lookup, canonalize it, and
1886 then search the default registered encoding converters for that encoding.
1887 If it's not within the default set and iconv() support has been compiled
1888 it, it will ask iconv for such an encoder. If this fails then the parser
1889 will report an error and stops processing:
1890 <pre>~/XML -&gt; ./xmllint err2.xml
1891err2.xml:1: error: Unsupported encoding UnsupportedEnc
1892&lt;?xml version="1.0" encoding="UnsupportedEnc"?&gt;
1893 ^</pre>
1894 </li>
1895 <li>From that point the encoder process progressingly the input (it is
1896 plugged as a front-end to the I/O module) for that entity. It captures
1897 and convert on-the-fly the document to be parsed to UTF-8. The parser
1898 itself just does UTF-8 checking of this input and process it
1899 transparently. The only difference is that the encoding information has
1900 been added to the parsing context (more precisely to the input
1901 corresponding to this entity).</li>
1902 <li>The result (when using DOM) is an internal form completely in UTF-8
1903 with just an encoding information on the document node.</li>
1904</ol>
1905
1906<p>Ok then what's happen when saving the document (assuming you
1907colllected/built an xmlDoc DOM like structure) ? It depends on the function
1908called, xmlSaveFile() will just try to save in the original encoding, while
1909xmlSaveFileTo() and xmlSaveFileEnc() can optionally save to a given
1910encoding:</p>
1911<ol>
1912 <li>if no encoding is given, libxml will look for an encoding value
1913 associated to the document and if it exists will try to save to that
1914 encoding,
1915 <p>otherwise everything is written in the internal form, i.e. UTF-8</p>
1916 </li>
1917 <li>so if an encoding was specified, either at the API level or on the
1918 document, libxml will again canonalize the encoding name, lookup for a
1919 converter in the registered set or through iconv. If not found the
1920 function will return an error code</li>
1921 <li>the converter is placed before the I/O buffer layer, as another kind of
1922 buffer, then libxml will simply push the UTF-8 serialization to through
1923 that buffer, which will then progressively be converted and pushed onto
1924 the I/O layer.</li>
1925 <li>It is possible that the converter code fails on some input, for example
1926 trying to push an UTF-8 encoded chinese character through the UTF-8 to
1927 ISO-8859-1 converter won't work. Since the encoders are progressive they
1928 will just report the error and the number of bytes converted, at that
1929 point libxml will decode the offending character, remove it from the
1930 buffer and replace it with the associated charRef encoding &amp;#123; and
1931 resume the convertion. This guarante that any document will be saved
1932 without losses (except for markup names where this is not legal, this is
1933 a problem in the current version, in pactice avoid using non-ascci
1934 characters for tags or attributes names @@). A special "ascii" encoding
1935 name is used to save documents to a pure ascii form can be used when
1936 portability is really crucial</li>
1937</ol>
1938
1939<p>Here is a few examples based on the same test document:</p>
1940<pre>~/XML -&gt; ./xmllint isolat1
1941&lt;?xml version="1.0" encoding="ISO-8859-1"?&gt;
1942&lt;très&gt;là&lt;/très&gt;
1943~/XML -&gt; ./xmllint --encode UTF-8 isolat1
1944&lt;?xml version="1.0" encoding="UTF-8"?&gt;
1945&lt;très&gt;là  &lt;/très&gt;
1946~/XML -&gt; </pre>
1947
1948<p>The same processing is applied (and reuse most of the code) for HTML I18N
1949processing. Looking up and modifying the content encoding is a bit more
1950difficult since it is located in a &lt;meta&gt; tag under the &lt;head&gt;,
1951so a couple of functions htmlGetMetaEncoding() and htmlSetMetaEncoding() have
1952been provided. The parser also attempts to switch encoding on the fly when
1953detecting such a tag on input. Except for that the processing is the same
1954(and again reuses the same code).</p>
1955
1956<h3><a name="Default">Default supported encodings</a></h3>
1957
1958<p>libxml has a set of default converters for the following encodings
1959(located in encoding.c):</p>
1960<ol>
1961 <li>UTF-8 is supported by default (null handlers)</li>
1962 <li>UTF-16, both little and big endian</li>
1963 <li>ISO-Latin-1 (ISO-8859-1) covering most western languages</li>
1964 <li>ASCII, useful mostly for saving</li>
1965 <li>HTML, a specific handler for the conversion of UTF-8 to ASCII with HTML
1966 predefined entities like &amp;copy; for the Copyright sign.</li>
1967</ol>
1968
1969<p>More over when compiled on an Unix platfor with iconv support the full set
1970of encodings supported by iconv can be instantly be used by libxml. On a
1971linux machine with glibc-2.1 the list of supported encodings and aliases fill
19723 full pages, and include UCS-4, the full set of ISO-Latin encodings, and the
1973various Japanese ones.</p>
1974
1975<h4>Encoding aliases</h4>
1976
1977<p>From 2.2.3, libxml has support to register encoding names aliases. The
1978goal is to be able to parse document whose encoding is supported but where
1979the name differs (for example from the default set of names accepted by
1980iconv). The following functions allow to register and handle new aliases for
1981existing encodings. Once registered libxml will automatically lookup the
1982aliases when handling a document:</p>
1983<ul>
1984 <li>int xmlAddEncodingAlias(const char *name, const char *alias);</li>
1985 <li>int xmlDelEncodingAlias(const char *alias);</li>
1986 <li>const char * xmlGetEncodingAlias(const char *alias);</li>
1987 <li>void xmlCleanupEncodingAliases(void);</li>
1988</ul>
1989
1990<h3><a name="extend">How to extend the existing support</a></h3>
1991
1992<p>Well adding support for new encoding, or overriding one of the encoders
1993(assuming it is buggy) should not be hard, just write an input and output
1994conversion routines to/from UTF-8, and register them using
1995xmlNewCharEncodingHandler(name, xxxToUTF8, UTF8Toxxx), and they will be
1996called automatically if the parser(s) encounter such an encoding name
1997(register it uppercase, this will help). The description of the encoders,
1998their arguments and expected return values are described in the encoding.h
1999header.</p>
2000
2001<p>A quick note on the topic of subverting the parser to use a different
2002internal encoding than UTF-8, in some case people will absolutely want to
2003keep the internal encoding different, I think it's still possible (but the
2004encoding must be compliant with ASCII on the same subrange) though I didn't
2005tried it. The key is to override the default conversion routines (by
2006registering null encoders/decoders for your charsets), and bypass the UTF-8
2007checking of the parser by setting the parser context charset
2008(ctxt-&gt;charset) to something different than XML_CHAR_ENCODING_UTF8, but
2009there is no guarantee taht this will work. You may also have some troubles
2010saving back.</p>
2011
2012<p>Basically proper I18N support is important, this requires at least
2013libxml-2.0.0, but a lot of features and corrections are really available only
2014starting 2.2.</p>
2015
2016<h2><a name="IO">I/O Interfaces</a></h2>
2017
2018<p>Table of Content:</p>
2019<ol>
2020 <li><a href="#General1">General overview</a></li>
2021 <li><a href="#basic">The basic buffer type</a></li>
2022 <li><a href="#Input">Input I/O handlers</a></li>
2023 <li><a href="#Output">Output I/O handlers</a></li>
2024 <li><a href="#entities">The entities loader</a></li>
2025 <li><a href="#Example2">Example of customized I/O</a></li>
2026</ol>
2027
2028<h3><a name="General1">General overview</a></h3>
2029
2030<p>The module <code><a
2031href="http://xmlsoft.org/html/libxml-xmlio.html">xmlIO.h</a></code> provides
2032the interfaces to the libxml I/O system. This consists of 4 main parts:</p>
2033<ul>
2034 <li>Entities loader, this is a routine which tries to fetch the entities
2035 (files) based on their PUBLIC and SYSTEM identifiers. The default loader
2036 don't look at the public identifier since libxml do not maintain a
2037 catalog. You can redefine you own entity loader by using
2038 <code>xmlGetExternalEntityLoader()</code> and
Daniel Veillard9c466822001-10-25 12:03:39 +0000[diff] [blame]2039 <code>xmlSetExternalEntityLoader()</code>. <a href="#entities">Check the
2040 example</a>.</li>
Daniel Veillardb8cfbd12001-10-25 10:53:28 +0000[diff] [blame]2041 <li>Input I/O buffers which are a commodity structure used by the parser(s)
2042 input layer to handle fetching the informations to feed the parser. This
2043 provides buffering and is also a placeholder where the encoding
2044 convertors to UTF8 are piggy-backed.</li>
2045 <li>Output I/O buffers are similar to the Input ones and fulfill similar
2046 task but when generating a serialization from a tree.</li>
2047 <li>A mechanism to register sets of I/O callbacks and associate them with
2048 specific naming schemes like the protocol part of the URIs.
2049 <p>This affect the default I/O operations and allows to use specific I/O
2050 handlers for certain names.</p>
2051 </li>
2052</ul>
2053
2054<p>The general mechanism used when loading http://rpmfind.net/xml.html for
2055example in the HTML parser is the following:</p>
2056<ol>
2057 <li>The default entity loader calls <code>xmlNewInputFromFile()</code> with
2058 the parsing context and the URI string.</li>
2059 <li>the URI string is checked against the existing registered handlers
2060 using their match() callback function, if the HTTP module was compiled
2061 in, it is registered and its match() function will succeeds</li>
2062 <li>the open() function of the handler is called and if successful will
2063 return an I/O Input buffer</li>
2064 <li>the parser will the start reading from this buffer and progressively
2065 fetch information from the resource, calling the read() function of the
2066 handler until the resource is exhausted</li>
2067 <li>if an encoding change is detected it will be installed on the input
2068 buffer, providing buffering and efficient use of the conversion
2069 routines</li>
2070 <li>once the parser has finished, the close() function of the handler is
2071 called once and the Input buffer and associed resources are
2072 deallocated.</li>
2073</ol>
2074
2075<p>The user defined callbacks are checked first to allow overriding of the
2076default libxml I/O routines.</p>
2077
2078<h3><a name="basic">The basic buffer type</a></h3>
2079
2080<p>All the buffer manipulation handling is done using the
2081<code>xmlBuffer</code> type define in <code><a
2082href="http://xmlsoft.org/html/libxml-tree.html">tree.h</a> </code>which is a
2083resizable memory buffer. The buffer allocation strategy can be selected to be
2084either best-fit or use an exponential doubling one (CPU vs. memory use
2085tradeoff). The values are <code>XML_BUFFER_ALLOC_EXACT</code> and
2086<code>XML_BUFFER_ALLOC_DOUBLEIT</code>, and can be set individually or on a
2087system wide basis using <code>xmlBufferSetAllocationScheme()</code>. A number
2088of functions allows to manipulate buffers with names starting with the
2089<code>xmlBuffer...</code> prefix.</p>
2090
2091<h3><a name="Input">Input I/O handlers</a></h3>
2092
2093<p>An Input I/O handler is a simple structure
2094<code>xmlParserInputBuffer</code> containing a context associated to the
2095resource (file descriptor, or pointer to a protocol handler), the read() and
2096close() callbacks to use and an xmlBuffer. And extra xmlBuffer and a charset
2097encoding handler are also present to support charset conversion when
2098needed.</p>
2099
2100<h3><a name="Output">Output I/O handlers</a></h3>
2101
2102<p>An Output handler <code>xmlOutputBuffer</code> is completely similar to an
2103Input one except the callbacks are write() and close().</p>
2104
2105<h3><a name="entities">The entities loader</a></h3>
2106
2107<p>The entity loader resolves requests for new entities and create inputs for
2108the parser. Creating an input from a filename or an URI string is done
2109through the xmlNewInputFromFile() routine. The default entity loader do not
2110handle the PUBLIC identifier associated with an entity (if any). So it just
2111calls xmlNewInputFromFile() with the SYSTEM identifier (which is mandatory in
2112XML).</p>
2113
2114<p>If you want to hook up a catalog mechanism then you simply need to
2115override the default entity loader, here is an example:</p>
2116<pre>#include &lt;libxml/xmlIO.h&gt;
2117
2118xmlExternalEntityLoader defaultLoader = NULL;
2119
2120xmlParserInputPtr
2121xmlMyExternalEntityLoader(const char *URL, const char *ID,
2122 xmlParserCtxtPtr ctxt) {
2123 xmlParserInputPtr ret;
2124 const char *fileID = NULL;
2125 /* lookup for the fileID depending on ID */
2126
2127 ret = xmlNewInputFromFile(ctxt, fileID);
2128 if (ret != NULL)
2129 return(ret);
2130 if (defaultLoader != NULL)
2131 ret = defaultLoader(URL, ID, ctxt);
2132 return(ret);
2133}
2134
2135int main(..) {
2136 ...
2137
2138 /*
2139 * Install our own entity loader
2140 */
2141 defaultLoader = xmlGetExternalEntityLoader();
2142 xmlSetExternalEntityLoader(xmlMyExternalEntityLoader);
2143
2144 ...
2145}</pre>
2146
2147<h3><a name="Example2">Example of customized I/O</a></h3>
2148
2149<p>This example come from <a href="http://xmlsoft.org/messages/0708.html">a
2150real use case</a>, xmlDocDump() closes the FILE * passed by the application
2151and this was a problem. The <a
2152href="http://xmlsoft.org/messages/0711.html">solution</a> was to redefine a
2153new output handler with the closing call deactivated:</p>
2154<ol>
2155 <li>First define a new I/O ouput allocator where the output don't close the
2156 file:
2157 <pre>xmlOutputBufferPtr
2158xmlOutputBufferCreateOwn(FILE *file, xmlCharEncodingHandlerPtr encoder) {
2159    xmlOutputBufferPtr ret;
2160    
2161    if (xmlOutputCallbackInitialized == 0)
2162        xmlRegisterDefaultOutputCallbacks();
2163
2164    if (file == NULL) return(NULL);
2165    ret = xmlAllocOutputBuffer(encoder);
2166    if (ret != NULL) {
2167        ret-&gt;context = file;
2168        ret-&gt;writecallback = xmlFileWrite;
2169        ret-&gt;closecallback = NULL; /* No close callback */
2170    }
2171    return(ret); <br>
2172
2173
2174
Daniel Veillard9c466822001-10-25 12:03:39 +0000[diff] [blame]2175
2176
Daniel Veillardc6271d22001-10-27 07:50:58 +0000[diff] [blame]2177
Daniel Veillard51095312001-10-28 18:51:57 +0000[diff] [blame]2178
Daniel Veillard52dcab32001-10-30 12:51:17 +0000[diff] [blame]2179
Daniel Veillarded421aa2001-11-04 21:22:45 +0000[diff] [blame]2180
Daniel Veillard43d3f612001-11-10 11:57:23 +0000[diff] [blame]2181
Daniel Veillarda4871052001-11-26 13:19:48 +0000[diff] [blame]2182
Daniel Veillard1aadc442001-11-28 13:10:32 +0000[diff] [blame]2183
Daniel Veillardef90ba72001-12-07 14:24:22 +0000[diff] [blame]2184
Daniel Veillard9ae4b7a2001-12-13 14:24:09 +0000[diff] [blame]2185
Daniel Veillard845cce42002-01-09 11:51:37 +0000[diff] [blame^]2186
Daniel Veillardb8cfbd12001-10-25 10:53:28 +0000[diff] [blame]2187} </pre>
2188 </li>
2189 <li>And then use it to save the document:
2190 <pre>FILE *f;
2191xmlOutputBufferPtr output;
2192xmlDocPtr doc;
2193int res;
2194
2195f = ...
2196doc = ....
2197
2198output = xmlOutputBufferCreateOwn(f, NULL);
2199res = xmlSaveFileTo(output, doc, NULL);
2200 </pre>
2201 </li>
2202</ol>
2203
2204<h2><a name="Catalog">Catalog support</a></h2>
2205
2206<p>Table of Content:</p>
2207<ol>
2208 <li><a href="General2">General overview</a></li>
2209 <li><a href="#definition">The definition</a></li>
2210 <li><a href="#Simple">Using catalogs</a></li>
2211 <li><a href="#Some">Some examples</a></li>
2212 <li><a href="#reference">How to tune catalog usage</a></li>
2213 <li><a href="#validate">How to debug catalog processing</a></li>
2214 <li><a href="#Declaring">How to create and maintain catalogs</a></li>
2215 <li><a href="#implemento">The implementor corner quick review of the
2216 API</a></li>
2217 <li><a href="#Other">Other resources</a></li>
2218</ol>
2219
2220<h3><a name="General2">General overview</a></h3>
2221
2222<p>What is a catalog? Basically it's a lookup mechanism used when an entity
2223(a file or a remote resource) references another entity. The catalog lookup
2224is inserted between the moment the reference is recognized by the software
2225(XML parser, stylesheet processing, or even images referenced for inclusion
2226in a rendering) and the time where loading that resource is actually
2227started.</p>
2228
2229<p>It is basically used for 3 things:</p>
2230<ul>
2231 <li>mapping from "logical" names, the public identifiers and a more
2232 concrete name usable for download (and URI). For example it can associate
2233 the logical name
2234 <p>"-//OASIS//DTD DocBook XML V4.1.2//EN"</p>
2235 <p>of the DocBook 4.1.2 XML DTD with the actual URL where it can be
2236 downloaded</p>
2237 <p>http://www.oasis-open.org/docbook/xml/4.1.2/docbookx.dtd</p>
2238 </li>
2239 <li>remapping from a given URL to another one, like an HTTP indirection
2240 saying that
2241 <p>"http://www.oasis-open.org/committes/tr.xsl"</p>
2242 <p>should really be looked at</p>
2243 <p>"http://www.oasis-open.org/committes/entity/stylesheets/base/tr.xsl"</p>
2244 </li>
2245 <li>providing a local cache mechanism allowing to load the entities
2246 associated to public identifiers or remote resources, this is a really
2247 important feature for any significant deployment of XML or SGML since it
2248 allows to avoid the aleas and delays associated to fetching remote
2249 resources.</li>
2250</ul>
2251
2252<h3><a name="definition">The definitions</a></h3>
2253
2254<p>Libxml, as of 2.4.3 implements 2 kind of catalogs:</p>
2255<ul>
2256 <li>the older SGML catalogs, the official spec is SGML Open Technical
2257 Resolution TR9401:1997, but is better understood by reading <a
2258 href="http://www.jclark.com/sp/catalog.htm">the SP Catalog page</a> from
2259 James Clark. This is relatively old and not the preferred mode of
2260 operation of libxml.</li>
2261 <li><a href="http://www.oasis-open.org/committees/entity/spec.html">XML
2262 Catalogs</a>
2263 is far more flexible, more recent, uses an XML syntax and should scale
2264 quite better. This is the default option of libxml.</li>
2265</ul>
2266
2267<p></p>
2268
2269<h3><a name="Simple">Using catalog</a></h3>
2270
2271<p>In a normal environment libxml will by default check the presence of a
2272catalog in /etc/xml/catalog, and assuming it has been correctly populated,
2273the processing is completely transparent to the document user. To take a
2274concrete example, suppose you are authoring a DocBook document, this one
2275starts with the following DOCTYPE definition:</p>
2276<pre>&lt;?xml version='1.0'?&gt;
2277&lt;!DOCTYPE book PUBLIC "-//Norman Walsh//DTD DocBk XML V3.1.4//EN"
2278 "http://nwalsh.com/docbook/xml/3.1.4/db3xml.dtd"&gt;</pre>
2279
2280<p>When validating the document with libxml, the catalog will be
2281automatically consulted to lookup the public identifier "-//Norman Walsh//DTD
2282DocBk XML V3.1.4//EN" and the system identifier
2283"http://nwalsh.com/docbook/xml/3.1.4/db3xml.dtd", and if these entities have
2284been installed on your system and the catalogs actually point to them, libxml
2285will fetch them from the local disk.</p>
2286
2287<p style="font-size: 10pt"><strong>Note</strong>: Really don't use this
2288DOCTYPE example it's a really old version, but is fine as an example.</p>
2289
2290<p>Libxml will check the catalog each time that it is requested to load an
2291entity, this includes DTD, external parsed entities, stylesheets, etc ... If
2292your system is correctly configured all the authoring phase and processing
2293should use only local files, even if your document stays portable because it
2294uses the canonical public and system ID, referencing the remote document.</p>
2295
2296<h3><a name="Some">Some examples:</a></h3>
2297
2298<p>Here is a couple of fragments from XML Catalogs used in libxml early
2299regression tests in <code>test/catalogs</code> :</p>
2300<pre>&lt;?xml version="1.0"?&gt;
2301&lt;!DOCTYPE catalog PUBLIC
2302 "-//OASIS//DTD Entity Resolution XML Catalog V1.0//EN"
2303 "http://www.oasis-open.org/committees/entity/release/1.0/catalog.dtd"&gt;
2304&lt;catalog xmlns="urn:oasis:names:tc:entity:xmlns:xml:catalog"&gt;
2305 &lt;public publicId="-//OASIS//DTD DocBook XML V4.1.2//EN"
2306 uri="http://www.oasis-open.org/docbook/xml/4.1.2/docbookx.dtd"/&gt;
2307...</pre>
2308
2309<p>This is the beginning of a catalog for DocBook 4.1.2, XML Catalogs are
2310written in XML, there is a specific namespace for catalog elements
2311"urn:oasis:names:tc:entity:xmlns:xml:catalog". The first entry in this
2312catalog is a <code>public</code> mapping it allows to associate a Public
2313Identifier with an URI.</p>
2314<pre>...
2315 &lt;rewriteSystem systemIdStartString="http://www.oasis-open.org/docbook/"
2316 rewritePrefix="file:///usr/share/xml/docbook/"/&gt;
2317...</pre>
2318
2319<p>A <code>rewriteSystem</code> is a very powerful instruction, it says that
2320any URI starting with a given prefix should be looked at another URI
2321constructed by replacing the prefix with an new one. In effect this acts like
2322a cache system for a full area of the Web. In practice it is extremely useful
2323with a file prefix if you have installed a copy of those resources on your
2324local system.</p>
2325<pre>...
2326&lt;delegatePublic publicIdStartString="-//OASIS//DTD XML Catalog //"
2327 catalog="file:///usr/share/xml/docbook.xml"/&gt;
2328&lt;delegatePublic publicIdStartString="-//OASIS//ENTITIES DocBook XML"
2329 catalog="file:///usr/share/xml/docbook.xml"/&gt;
2330&lt;delegatePublic publicIdStartString="-//OASIS//DTD DocBook XML"
2331 catalog="file:///usr/share/xml/docbook.xml"/&gt;
2332&lt;delegateSystem systemIdStartString="http://www.oasis-open.org/docbook/"
2333 catalog="file:///usr/share/xml/docbook.xml"/&gt;
2334&lt;delegateURI uriStartString="http://www.oasis-open.org/docbook/"
2335 catalog="file:///usr/share/xml/docbook.xml"/&gt;
2336...</pre>
2337
2338<p>Delegation is the core features which allows to build a tree of catalogs,
2339easier to maintain than a single catalog, based on Public Identifier, System
2340Identifier or URI prefixes it instructs the catalog software to look up
2341entries in another resource. This feature allow to build hierarchies of
2342catalogs, the set of entries presented should be sufficient to redirect the
2343resolution of all DocBook references to the specific catalog in
2344<code>/usr/share/xml/docbook.xml</code> this one in turn could delegate all
2345references for DocBook 4.2.1 to a specific catalog installed at the same time
2346as the DocBook resources on the local machine.</p>
2347
2348<h3><a name="reference">How to tune catalog usage:</a></h3>
2349
2350<p>The user can change the default catalog behaviour by redirecting queries
2351to its own set of catalogs, this can be done by setting the
2352<code>XML_CATALOG_FILES</code> environment variable to a list of catalogs, an
2353empty one should deactivate loading the default <code>/etc/xml/catalog</code>
2354default catalog</p>
2355
2356<h3><a name="validate">How to debug catalog processing:</a></h3>
2357
2358<p>Setting up the <code>XML_DEBUG_CATALOG</code> environment variable will
2359make libxml output debugging informations for each catalog operations, for
2360example:</p>
2361<pre>orchis:~/XML -&gt; xmllint --memory --noout test/ent2
2362warning: failed to load external entity "title.xml"
2363orchis:~/XML -&gt; export XML_DEBUG_CATALOG=
2364orchis:~/XML -&gt; xmllint --memory --noout test/ent2
2365Failed to parse catalog /etc/xml/catalog
2366Failed to parse catalog /etc/xml/catalog
2367warning: failed to load external entity "title.xml"
2368Catalogs cleanup
2369orchis:~/XML -&gt; </pre>
2370
2371<p>The test/ent2 references an entity, running the parser from memory makes
2372the base URI unavailable and the the "title.xml" entity cannot be loaded.
2373Setting up the debug environment variable allows to detect that an attempt is
2374made to load the <code>/etc/xml/catalog</code> but since it's not present the
2375resolution fails.</p>
2376
2377<p>But the most advanced way to debug XML catalog processing is to use the
2378<strong>xmlcatalog</strong> command shipped with libxml2, it allows to load
2379catalogs and make resolution queries to see what is going on. This is also
2380used for the regression tests:</p>
2381<pre>orchis:~/XML -&gt; ./xmlcatalog test/catalogs/docbook.xml \
2382 "-//OASIS//DTD DocBook XML V4.1.2//EN"
2383http://www.oasis-open.org/docbook/xml/4.1.2/docbookx.dtd
2384orchis:~/XML -&gt; </pre>
2385
2386<p>For debugging what is going on, adding one -v flags increase the verbosity
2387level to indicate the processing done (adding a second flag also indicate
2388what elements are recognized at parsing):</p>
2389<pre>orchis:~/XML -&gt; ./xmlcatalog -v test/catalogs/docbook.xml \
2390 "-//OASIS//DTD DocBook XML V4.1.2//EN"
2391Parsing catalog test/catalogs/docbook.xml's content
2392Found public match -//OASIS//DTD DocBook XML V4.1.2//EN
2393http://www.oasis-open.org/docbook/xml/4.1.2/docbookx.dtd
2394Catalogs cleanup
2395orchis:~/XML -&gt; </pre>
2396
2397<p>A shell interface is also available to debug and process multiple queries
2398(and for regression tests):</p>
2399<pre>orchis:~/XML -&gt; ./xmlcatalog -shell test/catalogs/docbook.xml \
2400 "-//OASIS//DTD DocBook XML V4.1.2//EN"
2401&gt; help
2402Commands available:
2403public PublicID: make a PUBLIC identifier lookup
2404system SystemID: make a SYSTEM identifier lookup
2405resolve PublicID SystemID: do a full resolver lookup
2406add 'type' 'orig' 'replace' : add an entry
2407del 'values' : remove values
2408dump: print the current catalog state
2409debug: increase the verbosity level
2410quiet: decrease the verbosity level
2411exit: quit the shell
2412&gt; public "-//OASIS//DTD DocBook XML V4.1.2//EN"
2413http://www.oasis-open.org/docbook/xml/4.1.2/docbookx.dtd
2414&gt; quit
2415orchis:~/XML -&gt; </pre>
2416
2417<p>This should be sufficient for most debugging purpose, this was actually
2418used heavily to debug the XML Catalog implementation itself.</p>
2419
2420<h3><a name="Declaring">How to create and maintain</a> catalogs:</h3>
2421
2422<p>Basically XML Catalogs are XML files, you can either use XML tools to
2423manage them or use <strong>xmlcatalog</strong> for this. The basic step is
2424to create a catalog the -create option provide this facility:</p>
2425<pre>orchis:~/XML -&gt; ./xmlcatalog --create tst.xml
2426&lt;?xml version="1.0"?&gt;
2427&lt;!DOCTYPE catalog PUBLIC "-//OASIS//DTD Entity Resolution XML Catalog V1.0//EN"
2428 "http://www.oasis-open.org/committees/entity/release/1.0/catalog.dtd"&gt;
2429&lt;catalog xmlns="urn:oasis:names:tc:entity:xmlns:xml:catalog"/&gt;
2430orchis:~/XML -&gt; </pre>
2431
2432<p>By default xmlcatalog does not overwrite the original catalog and save the
2433result on the standard output, this can be overridden using the -noout
2434option. The <code>-add</code> command allows to add entries in the
2435catalog:</p>
2436<pre>orchis:~/XML -&gt; ./xmlcatalog --noout --create --add "public" \
2437 "-//OASIS//DTD DocBook XML V4.1.2//EN" \
2438 http://www.oasis-open.org/docbook/xml/4.1.2/docbookx.dtd tst.xml
2439orchis:~/XML -&gt; cat 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;
2444&lt;public publicId="-//OASIS//DTD DocBook XML V4.1.2//EN"
2445 uri="http://www.oasis-open.org/docbook/xml/4.1.2/docbookx.dtd"/&gt;
2446&lt;/catalog&gt;
2447orchis:~/XML -&gt; </pre>
2448
2449<p>The <code>-add</code> option will always take 3 parameters even if some of
2450the XML Catalog constructs (like nextCatalog) will have only a single
2451argument, just pass a third empty string, it will be ignored.</p>
2452
2453<p>Similarly the <code>-del</code> option remove matching entries from the
2454catalog:</p>
2455<pre>orchis:~/XML -&gt; ./xmlcatalog --del \
2456 "http://www.oasis-open.org/docbook/xml/4.1.2/docbookx.dtd" tst.xml
2457&lt;?xml version="1.0"?&gt;
2458&lt;!DOCTYPE catalog PUBLIC "-//OASIS//DTD Entity Resolution XML Catalog V1.0//EN"
2459 "http://www.oasis-open.org/committees/entity/release/1.0/catalog.dtd"&gt;
2460&lt;catalog xmlns="urn:oasis:names:tc:entity:xmlns:xml:catalog"/&gt;
2461orchis:~/XML -&gt; </pre>
2462
2463<p>The catalog is now empty. Note that the matching of <code>-del</code> is
2464exact and would have worked in a similar fashion with the Public ID
2465string.</p>
2466
2467<p>This is rudimentary but should be sufficient to manage a not too complex
2468catalog tree of resources.</p>
2469
2470<h3><a name="implemento">The implementor corner quick review of the
2471API:</a></h3>
2472
2473<p>First, and like for every other module of libxml, there is an
2474automatically generated <a href="html/libxml-catalog.html">API page for
2475catalog support</a>.</p>
2476
2477<p>The header for the catalog interfaces should be included as:</p>
2478<pre>#include &lt;libxml/catalog.h&gt;</pre>
2479
2480<p>The API is voluntarily kept very simple. First it is not obvious that
2481applications really need access to it since it is the default behaviour of
2482libxml (Note: it is possible to completely override libxml default catalog by
2483using <a href="html/libxml-parser.html">xmlSetExternalEntityLoader</a> to
2484plug an application specific resolver).</p>
2485
2486<p>Basically libxml support 2 catalog lists:</p>
2487<ul>
2488 <li>the default one, global shared by all the application</li>
2489 <li>a per-document catalog, this one is built if the document uses the
2490 <code>oasis-xml-catalog</code> PIs to specify its own catalog list, it is
2491 associated to the parser context and destroyed when the parsing context
2492 is destroyed.</li>
2493</ul>
2494
2495<p>the document one will be used first if it exists.</p>
2496
2497<h4>Initialization routines:</h4>
2498
2499<p>xmlInitializeCatalog(), xmlLoadCatalog() and xmlLoadCatalogs() should be
2500used at startup to initialize the catalog, if the catalog should be
2501initialized with specific values xmlLoadCatalog() or xmlLoadCatalogs()
2502should be called before xmlInitializeCatalog() which would otherwise do a
2503default initialization first.</p>
2504
2505<p>The xmlCatalogAddLocal() call is used by the parser to grow the document
2506own catalog list if needed.</p>
2507
2508<h4>Preferences setup:</h4>
2509
2510<p>The XML Catalog spec requires the possibility to select default
2511preferences between public and system delegation,
2512xmlCatalogSetDefaultPrefer() allows this, xmlCatalogSetDefaults() and
2513xmlCatalogGetDefaults() allow to control if XML Catalogs resolution should
2514be forbidden, allowed for global catalog, for document catalog or both, the
2515default is to allow both.</p>
2516
2517<p>And of course xmlCatalogSetDebug() allows to generate debug messages
2518(through the xmlGenericError() mechanism).</p>
2519
2520<h4>Querying routines:</h4>
2521
2522<p>xmlCatalogResolve(), xmlCatalogResolveSystem(), xmlCatalogResolvePublic()
2523and xmlCatalogResolveURI() are relatively explicit if you read the XML
2524Catalog specification they correspond to section 7 algorithms, they should
2525also work if you have loaded an SGML catalog with a simplified semantic.</p>
2526
2527<p>xmlCatalogLocalResolve() and xmlCatalogLocalResolveURI() are the same but
2528operate on the document catalog list</p>
2529
2530<h4>Cleanup and Miscellaneous:</h4>
2531
2532<p>xmlCatalogCleanup() free-up the global catalog, xmlCatalogFreeLocal() is
2533the per-document equivalent.</p>
2534
2535<p>xmlCatalogAdd() and xmlCatalogRemove() are used to dynamically modify the
2536first catalog in the global list, and xmlCatalogDump() allows to dump a
2537catalog state, those routines are primarily designed for xmlcatalog, I'm not
2538sure that exposing more complex interfaces (like navigation ones) would be
2539really useful.</p>
2540
2541<p>The xmlParseCatalogFile() is a function used to load XML Catalog files,
2542it's similar as xmlParseFile() except it bypass all catalog lookups, it's
2543provided because this functionality may be useful for client tools.</p>
2544
2545<h4>threaded environments:</h4>
2546
2547<p>Since the catalog tree is built progressively, some care has been taken to
2548try to avoid troubles in multithreaded environments. The code is now thread
2549safe assuming that the libxml library has been compiled with threads
2550support.</p>
2551
2552<p></p>
2553
2554<h3><a name="Other">Other resources</a></h3>
2555
2556<p>The XML Catalog specification is relatively recent so there isn't much
2557literature to point at:</p>
2558<ul>
2559 <li>You can find an good rant from Norm Walsh about <a
2560 href="http://www.arbortext.com/Think_Tank/XML_Resources/Issue_Three/issue_three.html">the
2561 need for catalogs</a>, it provides a lot of context informations even if
2562 I don't agree with everything presented.</li>
2563 <li>An <a href="http://home.ccil.org/~cowan/XML/XCatalog.html">old XML
2564 catalog proposal</a> from John Cowan</li>
2565 <li>The <a href="http://www.rddl.org/">Resource Directory Description
2566 Language</a> (RDDL) another catalog system but more oriented toward
2567 providing metadata for XML namespaces.</li>
2568 <li>the page from the OASIS Technical <a
2569 href="http://www.oasis-open.org/committees/entity/">Committee on Entity
2570 Resolution</a> who maintains XML Catalog, you will find pointers to the
2571 specification update, some background and pointers to others tools
2572 providing XML Catalog support</li>
2573 <li>I have uploaded <a href="ftp://xmlsoft.org/test/dbk412catalog.tar.gz">a
2574 mall tarball</a> containing XML Catalogs for DocBook 4.1.2 which seems to
2575 work fine for me</li>
2576 <li>The <a href="http://www.xmlsoft.org/xmlcatalog_man.html">xmlcatalog
2577 manual page</a></li>
2578</ul>
2579
2580<p>If you have suggestions for corrections or additions, simply contact
2581me:</p>
2582
2583<h2><a name="library">The parser interfaces</a></h2>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2584
2585<p>This section is directly intended to help programmers getting bootstrapped
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]2586using the XML library from the C language. It is not intended to be
2587extensive. I hope the automatically generated documents will provide the
2588completeness required, but as a separate set of documents. The interfaces of
2589the XML library are by principle low level, there is nearly zero abstraction.
2590Those interested in a higher level API should <a href="#DOM">look at
2591DOM</a>.</p>
Daniel Veillardccb09631998-10-27 06:21:04 +0000[diff] [blame]2592
Daniel Veillard9cb5ff42001-01-29 08:22:21 +0000[diff] [blame]2593<p>The <a href="html/libxml-parser.html">parser interfaces for XML</a> are
2594separated from the <a href="html/libxml-htmlparser.html">HTML parser
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]2595interfaces</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]2596
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]2597<h3><a name="Invoking">Invoking the parser : the pull method</a></h3>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2598
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]2599<p>Usually, the first thing to do is to read an XML input. The parser accepts
2600documents either from in-memory strings or from files. The functions are
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2601defined in "parser.h":</p>
Daniel Veillard10c6a8f1998-10-28 01:00:12 +0000[diff] [blame]2602<dl>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2603 <dt><code>xmlDocPtr xmlParseMemory(char *buffer, int size);</code></dt>
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]2604 <dd><p>Parse a null-terminated string containing the document.</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2605 </dd>
Daniel Veillard10c6a8f1998-10-28 01:00:12 +0000[diff] [blame]2606</dl>
2607<dl>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2608 <dt><code>xmlDocPtr xmlParseFile(const char *filename);</code></dt>
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]2609 <dd><p>Parse an XML document contained in a (possibly compressed)
2610 file.</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2611 </dd>
Daniel Veillard10c6a8f1998-10-28 01:00:12 +0000[diff] [blame]2612</dl>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2613
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]2614<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]2615failure).</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2616
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]2617<h3 id="Invoking1">Invoking the parser: the push method</h3>
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]2618
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]2619<p>In order for the application to keep the control when the document is
2620being fetched (which is common for GUI based programs) libxml provides a push
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]2621interface, too, as of version 1.8.3. Here are the interface functions:</p>
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]2622<pre>xmlParserCtxtPtr xmlCreatePushParserCtxt(xmlSAXHandlerPtr sax,
2623 void *user_data,
2624 const char *chunk,
2625 int size,
2626 const char *filename);
2627int xmlParseChunk (xmlParserCtxtPtr ctxt,
2628 const char *chunk,
2629 int size,
2630 int terminate);</pre>
2631
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]2632<p>and here is a simple example showing how to use the interface:</p>
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]2633<pre> FILE *f;
2634
2635 f = fopen(filename, "r");
2636 if (f != NULL) {
2637 int res, size = 1024;
2638 char chars[1024];
2639 xmlParserCtxtPtr ctxt;
2640
2641 res = fread(chars, 1, 4, f);
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]2642 if (res &gt; 0) {
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]2643 ctxt = xmlCreatePushParserCtxt(NULL, NULL,
2644 chars, res, filename);
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]2645 while ((res = fread(chars, 1, size, f)) &gt; 0) {
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]2646 xmlParseChunk(ctxt, chars, res, 0);
2647 }
2648 xmlParseChunk(ctxt, chars, 0, 1);
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]2649 doc = ctxt-&gt;myDoc;
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]2650 xmlFreeParserCtxt(ctxt);
2651 }
2652 }</pre>
2653
Daniel Veillardec70e912001-02-26 20:10:45 +0000[diff] [blame]2654<p>The HTML parser embedded into libxml also has a push interface; the
2655functions are just prefixed by "html" rather than "xml".</p>
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]2656
2657<h3 id="Invoking2">Invoking the parser: the SAX interface</h3>
2658
Daniel Veillardec70e912001-02-26 20:10:45 +0000[diff] [blame]2659<p>The tree-building interface makes the parser memory-hungry, first loading
2660the document in memory and then building the tree itself. Reading a document
2661without building the tree is possible using the SAX interfaces (see SAX.h and
2662<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]2663Henstridge's documentation</a>). Note also that the push interface can be
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]2664limited to SAX: just use the two first arguments of
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]2665<code>xmlCreatePushParserCtxt()</code>.</p>
Daniel Veillardccb09631998-10-27 06:21:04 +0000[diff] [blame]2666
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]2667<h3><a name="Building">Building a tree from scratch</a></h3>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2668
2669<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]2670there is a set of functions dedicated to building new elements. (These are
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]2671also described in &lt;libxml/tree.h&gt;.) For example, here is a piece of
2672code that produces the XML document used in the previous examples:</p>
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]2673<pre> #include &lt;libxml/tree.h&gt;
Daniel Veillard361d8452000-04-03 19:48:13 +0000[diff] [blame]2674 xmlDocPtr doc;
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]2675 xmlNodePtr tree, subtree;
2676
2677 doc = xmlNewDoc("1.0");
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]2678 doc-&gt;children = xmlNewDocNode(doc, NULL, "EXAMPLE", NULL);
2679 xmlSetProp(doc-&gt;children, "prop1", "gnome is great");
2680 xmlSetProp(doc-&gt;children, "prop2", "&amp; linux too");
2681 tree = xmlNewChild(doc-&gt;children, NULL, "head", NULL);
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]2682 subtree = xmlNewChild(tree, NULL, "title", "Welcome to Gnome");
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]2683 tree = xmlNewChild(doc-&gt;children, NULL, "chapter", NULL);
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]2684 subtree = xmlNewChild(tree, NULL, "title", "The Linux adventure");
2685 subtree = xmlNewChild(tree, NULL, "p", "bla bla bla ...");
2686 subtree = xmlNewChild(tree, NULL, "image", NULL);
2687 xmlSetProp(subtree, "href", "linus.gif");</pre>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2688
2689<p>Not really rocket science ...</p>
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]2690
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]2691<h3><a name="Traversing">Traversing the tree</a></h3>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2692
Daniel Veillard9cb5ff42001-01-29 08:22:21 +0000[diff] [blame]2693<p>Basically by <a href="html/libxml-tree.html">including "tree.h"</a> your
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]2694code has access to the internal structure of all the elements of the tree.
2695The names should be somewhat simple like <strong>parent</strong>,
Daniel Veillard306be992000-07-03 12:38:45 +0000[diff] [blame]2696<strong>children</strong>, <strong>next</strong>, <strong>prev</strong>,
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]2697<strong>properties</strong>, etc... For example, still with the previous
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]2698example:</p>
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]2699<pre><code>doc-&gt;children-&gt;children-&gt;children</code></pre>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2700
2701<p>points to the title element,</p>
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]2702<pre>doc-&gt;children-&gt;children-&gt;next-&gt;children-&gt;children</pre>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2703
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]2704<p>points to the text node containing the chapter title "The Linux
2705adventure".</p>
Daniel Veillard10c6a8f1998-10-28 01:00:12 +0000[diff] [blame]2706
Daniel Veillardb24054a1999-12-18 15:32:46 +0000[diff] [blame]2707<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]2708present before the document root, so <code>doc-&gt;children</code> may point
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]2709to an element which is not the document Root Element; a function
Daniel Veillard5cb5ab81999-12-21 15:35:29 +0000[diff] [blame]2710<code>xmlDocGetRootElement()</code> was added for this purpose.</p>
Daniel Veillardb24054a1999-12-18 15:32:46 +0000[diff] [blame]2711
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]2712<h3><a name="Modifying">Modifying the tree</a></h3>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2713
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]2714<p>Functions are provided for reading and writing the document content. Here
Daniel Veillard9cb5ff42001-01-29 08:22:21 +0000[diff] [blame]2715is an excerpt from the <a href="html/libxml-tree.html">tree API</a>:</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>xmlAttrPtr xmlSetProp(xmlNodePtr node, const xmlChar *name, const
2718 xmlChar *value);</code></dt>
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]2719 <dd><p>This sets (or changes) an attribute carried by an ELEMENT node.
2720 The value can be NULL.</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2721 </dd>
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]2722</dl>
2723<dl>
Daniel Veillarddd6b3671999-09-23 22:19:22 +0000[diff] [blame]2724 <dt><code>const xmlChar *xmlGetProp(xmlNodePtr node, const xmlChar
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2725 *name);</code></dt>
Daniel Veillardc92c3042000-09-29 02:42:04 +0000[diff] [blame]2726 <dd><p>This function returns a pointer to new copy of the property
2727 content. Note that the user must deallocate the result.</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2728 </dd>
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]2729</dl>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2730
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]2731<p>Two functions are provided for reading and writing the text associated
2732with elements:</p>
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]2733<dl>
Daniel Veillarddd6b3671999-09-23 22:19:22 +0000[diff] [blame]2734 <dt><code>xmlNodePtr xmlStringGetNodeList(xmlDocPtr doc, const xmlChar
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2735 *value);</code></dt>
Daniel Veillardec70e912001-02-26 20:10:45 +0000[diff] [blame]2736 <dd><p>This function takes an "external" string and converts it to one
2737 text node or possibly to a list of entity and text nodes. All
2738 non-predefined entity references like &amp;Gnome; will be stored
2739 internally as entity nodes, hence the result of the function may not be
2740 a single node.</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2741 </dd>
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]2742</dl>
2743<dl>
Daniel Veillarddd6b3671999-09-23 22:19:22 +0000[diff] [blame]2744 <dt><code>xmlChar *xmlNodeListGetString(xmlDocPtr doc, xmlNodePtr list, int
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2745 inLine);</code></dt>
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]2746 <dd><p>This function is the inverse of
2747 <code>xmlStringGetNodeList()</code>. It generates a new string
2748 containing the content of the text and entity nodes. Note the extra
2749 argument inLine. If this argument is set to 1, the function will expand
2750 entity references. For example, instead of returning the &amp;Gnome;
2751 XML encoding in the string, it will substitute it with its value (say,
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]2752 "GNU Network Object Model Environment").</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2753 </dd>
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]2754</dl>
Daniel Veillard10c6a8f1998-10-28 01:00:12 +0000[diff] [blame]2755
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]2756<h3><a name="Saving">Saving a tree</a></h3>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2757
2758<p>Basically 3 options are possible:</p>
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]2759<dl>
Daniel Veillarddd6b3671999-09-23 22:19:22 +0000[diff] [blame]2760 <dt><code>void xmlDocDumpMemory(xmlDocPtr cur, xmlChar**mem, int
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2761 *size);</code></dt>
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]2762 <dd><p>Returns a buffer into which the document has been saved.</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2763 </dd>
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]2764</dl>
2765<dl>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2766 <dt><code>extern void xmlDocDump(FILE *f, xmlDocPtr doc);</code></dt>
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]2767 <dd><p>Dumps a document to an open file descriptor.</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>int xmlSaveFile(const char *filename, xmlDocPtr cur);</code></dt>
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]2772 <dd><p>Saves the document to a file. In this case, the compression
2773 interface is triggered if it has been turned on.</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2774 </dd>
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]2775</dl>
Daniel Veillard10c6a8f1998-10-28 01:00:12 +0000[diff] [blame]2776
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]2777<h3><a name="Compressio">Compression</a></h3>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2778
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]2779<p>The library transparently handles compression when doing file-based
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]2780accesses. The level of compression on saves can be turned on either globally
2781or individually for one file:</p>
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]2782<dl>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2783 <dt><code>int xmlGetDocCompressMode (xmlDocPtr doc);</code></dt>
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]2784 <dd><p>Gets the document compression ratio (0-9).</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2785 </dd>
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]2786</dl>
2787<dl>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2788 <dt><code>void xmlSetDocCompressMode (xmlDocPtr doc, int mode);</code></dt>
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]2789 <dd><p>Sets the document compression ratio.</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2790 </dd>
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]2791</dl>
2792<dl>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2793 <dt><code>int xmlGetCompressMode(void);</code></dt>
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]2794 <dd><p>Gets the default compression ratio.</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2795 </dd>
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]2796</dl>
2797<dl>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2798 <dt><code>void xmlSetCompressMode(int mode);</code></dt>
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]2799 <dd><p>Sets the default compression ratio.</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2800 </dd>
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]2801</dl>
2802
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]2803<h2><a name="Entities">Entities or no entities</a></h2>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]2804
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]2805<p>Entities in principle are similar to simple C macros. An entity defines an
2806abbreviation for a given string that you can reuse many times throughout the
2807content of your document. Entities are especially useful when a given string
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]2808may occur frequently within a document, or to confine the change needed to a
2809document to a restricted area in the internal subset of the document (at the
2810beginning). Example:</p>
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]2811<pre>1 &lt;?xml version="1.0"?&gt;
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]28122 &lt;!DOCTYPE EXAMPLE SYSTEM "example.dtd" [
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]28133 &lt;!ENTITY xml "Extensible Markup Language"&gt;
28144 ]&gt;
28155 &lt;EXAMPLE&gt;
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]28166 &amp;xml;
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]28177 &lt;/EXAMPLE&gt;</pre>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]2818
2819<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]2820its name with '&amp;' and following it by ';' without any spaces added. There
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]2821are 5 predefined entities in libxml allowing you to escape charaters with
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]2822predefined meaning in some parts of the xml document content:
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]2823<strong>&amp;lt;</strong> for the character '&lt;', <strong>&amp;gt;</strong>
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]2824for the character '&gt;', <strong>&amp;apos;</strong> for the character ''',
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]2825<strong>&amp;quot;</strong> for the character '"', and
2826<strong>&amp;amp;</strong> for the character '&amp;'.</p>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]2827
2828<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]2829substitute an entity's content so that you can see the replacement text in
2830your application. Or you may prefer to keep entity references as such in the
2831content to be able to save the document back without losing this usually
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]2832precious information (if the user went through the pain of explicitly
2833defining entities, he may have a a rather negative attitude if you blindly
2834susbtitute them as saving time). The <a
Daniel Veillard9cb5ff42001-01-29 08:22:21 +0000[diff] [blame]2835href="html/libxml-parser.html#XMLSUBSTITUTEENTITIESDEFAULT">xmlSubstituteEntitiesDefault()</a>
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]2836function allows you to check and change the behaviour, which is to not
2837substitute entities by default.</p>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]2838
2839<p>Here is the DOM tree built by libxml for the previous document in the
2840default case:</p>
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]2841<pre>/gnome/src/gnome-xml -&gt; ./xmllint --debug test/ent1
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]2842DOCUMENT
2843version=1.0
2844 ELEMENT EXAMPLE
2845 TEXT
2846 content=
2847 ENTITY_REF
2848 INTERNAL_GENERAL_ENTITY xml
2849 content=Extensible Markup Language
2850 TEXT
2851 content=</pre>
2852
2853<p>And here is the result when substituting entities:</p>
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]2854<pre>/gnome/src/gnome-xml -&gt; ./tester --debug --noent test/ent1
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]2855DOCUMENT
2856version=1.0
2857 ELEMENT EXAMPLE
2858 TEXT
2859 content= Extensible Markup Language</pre>
2860
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]2861<p>So, entities or no entities? Basically, it depends on your use case. I
2862suggest that you keep the non-substituting default behaviour and avoid using
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]2863entities in your XML document or data if you are not willing to handle the
2864entity references elements in the DOM tree.</p>
2865
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]2866<p>Note that at save time libxml enforces the conversion of the predefined
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]2867entities where necessary to prevent well-formedness problems, and will also
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]2868transparently replace those with chars (i.e. it will not generate entity
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]2869reference elements in the DOM tree or call the reference() SAX callback when
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]2870finding them in the input).</p>
2871
Daniel Veillard7b9c4b72000-08-25 16:26:50 +0000[diff] [blame]2872<p><span style="background-color: #FF0000">WARNING</span>: handling entities
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]2873on top of the libxml SAX interface is difficult!!! If you plan to use
Daniel Veillard7b9c4b72000-08-25 16:26:50 +0000[diff] [blame]2874non-predefined entities in your documents, then the learning cuvre to handle
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]2875then 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]2876strongly suggest you consider using the DOM interface instead and let libxml
Daniel Veillard8c6d6af2000-08-25 17:14:13 +0000[diff] [blame]2877deal with the complexity rather than trying to do it yourself.</p>
Daniel Veillard7b9c4b72000-08-25 16:26:50 +0000[diff] [blame]2878
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]2879<h2><a name="Namespaces">Namespaces</a></h2>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]2880
Daniel Veillardec303412000-03-24 13:41:54 +0000[diff] [blame]2881<p>The libxml library implements <a
2882href="http://www.w3.org/TR/REC-xml-names/">XML namespaces</a> support by
2883recognizing namespace contructs in the input, and does namespace lookup
2884automatically when building the DOM tree. A namespace declaration is
2885associated with an in-memory structure and all elements or attributes within
2886that namespace point to it. Hence testing the namespace is a simple and fast
2887equality operation at the user level.</p>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]2888
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]2889<p>I suggest that people using libxml use a namespace, and declare it in the
2890root element of their document as the default namespace. Then they don't need
2891to 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]2892refinement and merging of data from different sources. This doesn't increase
Daniel Veillardec70e912001-02-26 20:10:45 +0000[diff] [blame]2893the size of the XML output significantly, but significantly increases its
2894value in the long-term. Example:</p>
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]2895<pre>&lt;mydoc xmlns="http://mydoc.example.org/schemas/"&gt;
2896 &lt;elem1&gt;...&lt;/elem1&gt;
2897 &lt;elem2&gt;...&lt;/elem2&gt;
2898&lt;/mydoc&gt;</pre>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]2899
Daniel Veillardec70e912001-02-26 20:10:45 +0000[diff] [blame]2900<p>The namespace value has to be an absolute URL, but the URL doesn't have to
2901point to any existing resource on the Web. It will bind all the element and
2902atributes with that URL. I suggest to use an URL within a domain you control,
2903and that the URL should contain some kind of version information if possible.
2904For example, <code>"http://www.gnome.org/gnumeric/1.0/"</code> is a good
2905namespace scheme.</p>
Daniel Veillardec303412000-03-24 13:41:54 +0000[diff] [blame]2906
2907<p>Then when you load a file, make sure that a namespace carrying the
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]2908version-independent prefix is installed on the root element of your document,
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]2909and if the version information don't match something you know, warn the user
2910and 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]2911namespace checking on the prefix value. &lt;foo:text&gt; may be exactly the
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]2912same as &lt;bar:text&gt; in another document. What really matters is the URI
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]2913associated with the element or the attribute, not the prefix string (which is
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]2914just a shortcut for the full URI). In libxml, element and attributes have an
Daniel Veillardec303412000-03-24 13:41:54 +0000[diff] [blame]2915<code>ns</code> field pointing to an xmlNs structure detailing the namespace
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]2916prefix and its URI.</p>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]2917
2918<p>@@Interfaces@@</p>
2919
2920<p>@@Examples@@</p>
2921
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]2922<p>Usually people object to using namespaces together with validity checking.
2923I will try to make sure that using namespaces won't break validity checking,
2924so even if you plan to use or currently are using validation I strongly
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]2925suggest adding namespaces to your document. A default namespace scheme
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]2926<code>xmlns="http://...."</code> should not break validity even on less
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]2927flexible parsers. Using namespaces to mix and differentiate content coming
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]2928from multiple DTDs will certainly break current validation schemes. I will
2929try to provide ways to do this, but this may not be portable or
2930standardized.</p>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]2931
Daniel Veillardb8cfbd12001-10-25 10:53:28 +0000[diff] [blame]2932<h2><a name="Upgrading">Upgrading 1.x code</a></h2>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]2933
Daniel Veillardb8cfbd12001-10-25 10:53:28 +0000[diff] [blame]2934<p>Incompatible changes:</p>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]2935
Daniel Veillardb8cfbd12001-10-25 10:53:28 +0000[diff] [blame]2936<p>Version 2 of libxml is the first version introducing serious backward
2937incompatible changes. The main goals were:</p>
2938<ul>
2939 <li>a general cleanup. A number of mistakes inherited from the very early
2940 versions couldn't be changed due to compatibility constraints. Example
2941 the "childs" element in the nodes.</li>
2942 <li>Uniformization of the various nodes, at least for their header and link
2943 parts (doc, parent, children, prev, next), the goal is a simpler
2944 programming model and simplifying the task of the DOM implementors.</li>
2945 <li>better conformances to the XML specification, for example version 1.x
2946 had an heuristic to try to detect ignorable white spaces. As a result the
2947 SAX event generated were ignorableWhitespace() while the spec requires
2948 character() in that case. This also mean that a number of DOM node
2949 containing blank text may populate the DOM tree which were not present
2950 before.</li>
2951</ul>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]2952
Daniel Veillardb8cfbd12001-10-25 10:53:28 +0000[diff] [blame]2953<h3>How to fix libxml-1.x code:</h3>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]2954
Daniel Veillardb8cfbd12001-10-25 10:53:28 +0000[diff] [blame]2955<p>So client code of libxml designed to run with version 1.x may have to be
2956changed to compile against version 2.x of libxml. Here is a list of changes
2957that I have collected, they may not be sufficient, so in case you find other
2958change which are required, <a href="mailto:Daniel.Ïeillardw3.org">drop me a
2959mail</a>:</p>
2960<ol>
2961 <li>The package name have changed from libxml to libxml2, the library name
2962 is now -lxml2 . There is a new xml2-config script which should be used to
2963 select the right parameters libxml2</li>
2964 <li>Node <strong>childs</strong> field has been renamed
2965 <strong>children</strong> so s/childs/children/g should be applied
2966 (probablility of having "childs" anywere else is close to 0+</li>
2967 <li>The document don't have anymore a <strong>root</strong> element it has
2968 been replaced by <strong>children</strong> and usually you will get a
2969 list of element here. For example a Dtd element for the internal subset
2970 and it's declaration may be found in that list, as well as processing
2971 instructions or comments found before or after the document root element.
2972 Use <strong>xmlDocGetRootElement(doc)</strong> to get the root element of
2973 a document. Alternatively if you are sure to not reference Dtds nor have
2974 PIs or comments before or after the root element
2975 s/-&gt;root/-&gt;children/g will probably do it.</li>
2976 <li>The white space issue, this one is more complex, unless special case of
2977 validating parsing, the line breaks and spaces usually used for indenting
2978 and formatting the document content becomes significant. So they are
2979 reported by SAX and if your using the DOM tree, corresponding nodes are
2980 generated. Too approach can be taken:
2981 <ol>
2982 <li>lazy one, use the compatibility call
2983 <strong>xmlKeepBlanksDefault(0)</strong> but be aware that you are
2984 relying on a special (and possibly broken) set of heuristics of
2985 libxml to detect ignorable blanks. Don't complain if it breaks or
2986 make your application not 100% clean w.r.t. to it's input.</li>
2987 <li>the Right Way: change you code to accept possibly unsignificant
2988 blanks characters, or have your tree populated with weird blank text
2989 nodes. You can spot them using the comodity function
2990 <strong>xmlIsBlankNode(node)</strong> returning 1 for such blank
2991 nodes.</li>
2992 </ol>
2993 <p>Note also that with the new default the output functions don't add any
2994 extra indentation when saving a tree in order to be able to round trip
2995 (read and save) without inflating the document with extra formatting
2996 chars.</p>
2997 </li>
2998 <li>The include path has changed to $prefix/libxml/ and the includes
2999 themselves uses this new prefix in includes instructions... If you are
3000 using (as expected) the
3001 <pre>xml2-config --cflags</pre>
3002 <p>output to generate you compile commands this will probably work out of
3003 the box</p>
3004 </li>
3005 <li>xmlDetectCharEncoding takes an extra argument indicating the lenght in
3006 byte of the head of the document available for character detection.</li>
3007</ol>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]3008
Daniel Veillardb8cfbd12001-10-25 10:53:28 +0000[diff] [blame]3009<h3>Ensuring both libxml-1.x and libxml-2.x compatibility</h3>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]3010
Daniel Veillardb8cfbd12001-10-25 10:53:28 +0000[diff] [blame]3011<p>Two new version of libxml (1.8.11) and libxml2 (2.3.4) have been released
3012to allow smoth upgrade of existing libxml v1code while retaining
3013compatibility. They offers the following:</p>
3014<ol>
3015 <li>similar include naming, one should use
3016 <strong>#include&lt;libxml/...&gt;</strong> in both cases.</li>
3017 <li>similar identifiers defined via macros for the child and root fields:
3018 respectively <strong>xmlChildrenNode</strong> and
3019 <strong>xmlRootNode</strong></li>
3020 <li>a new macro <strong>LIBXML_TEST_VERSION</strong> which should be
3021 inserted once in the client code</li>
3022</ol>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]3023
Daniel Veillardb8cfbd12001-10-25 10:53:28 +0000[diff] [blame]3024<p>So the roadmap to upgrade your existing libxml applications is the
3025following:</p>
3026<ol>
3027 <li>install the libxml-1.8.8 (and libxml-devel-1.8.8) packages</li>
3028 <li>find all occurences where the xmlDoc <strong>root</strong> field is
3029 used and change it to <strong>xmlRootNode</strong></li>
3030 <li>similary find all occurences where the xmlNode <strong>childs</strong>
3031 field is used and change it to <strong>xmlChildrenNode</strong></li>
3032 <li>add a <strong>LIBXML_TEST_VERSION</strong> macro somewhere in your
3033 <strong>main()</strong> or in the library init entry point</li>
3034 <li>Recompile, check compatibility, it should still work</li>
3035 <li>Change your configure script to look first for xml2-config and fallback
3036 using xml-config . Use the --cflags and --libs ouptut of the command as
3037 the Include and Linking parameters needed to use libxml.</li>
3038 <li>install libxml2-2.3.x and libxml2-devel-2.3.x (libxml-1.8.y and
3039 libxml-devel-1.8.y can be kept simultaneously)</li>
3040 <li>remove your config.cache, relaunch your configuration mechanism, and
3041 recompile, if steps 2 and 3 were done right it should compile as-is</li>
3042 <li>Test that your application is still running correctly, if not this may
3043 be due to extra empty nodes due to formating spaces being kept in libxml2
3044 contrary to libxml1, in that case insert xmlKeepBlanksDefault(1) in your
3045 code before calling the parser (next to
3046 <strong>LIBXML_TEST_VERSION</strong> is a fine place).</li>
3047</ol>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]3048
Daniel Veillardb8cfbd12001-10-25 10:53:28 +0000[diff] [blame]3049<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]3050
Daniel Veillardb8cfbd12001-10-25 10:53:28 +0000[diff] [blame]3051<p>Let me put some emphasis on the fact that there is far more changes from
3052libxml 1.x to 2.x than the ones you may have to patch for. The overall code
3053has been considerably cleaned up and the conformance to the XML specification
3054has been drastically improved too. Don't take those changes as an excuse to
3055not upgrade, it may cost a lot on the long term ...</p>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]3056
Daniel Veillard52dcab32001-10-30 12:51:17 +0000[diff] [blame]3057<h2><a name="Thread">Thread safety</a></h2>
3058
3059<p>Starting with 2.4.7, libxml makes provisions to ensure that concurent
3060threads can safely work in parallel parsing different documents. There is
3061however a couple of things to do to ensure it:</p>
3062<ul>
3063 <li>configure the library accordingly using the --with-threads options</li>
3064 <li>call xmlInitParser() in the "main" thread before using any of the
3065 libxml API (except possibly selecting a different memory allocator)</li>
3066</ul>
3067
3068<p>Note that the thread safety cannot be ensured for multiple threads sharing
3069the same document, the locking must be done at the application level, libxml
3070exports a basic mutex and reentrant mutexes API in &lt;libxml/threads.h&gt;.
3071The parts of the library checked for thread safety are:</p>
3072<ul>
3073 <li>concurrent loading</li>
3074 <li>file access resolution</li>
3075 <li>catalog access</li>
3076 <li>catalog building</li>
3077 <li>entities lookup/accesses</li>
3078 <li>validation</li>
3079 <li>global variables per-thread override</li>
3080 <li>memory handling</li>
3081</ul>
3082
3083<p>XPath is supposed to be thread safe now, but this wasn't tested
3084seriously.</p>
3085
Daniel Veillard35008381999-10-25 13:15:52 +0000[diff] [blame]3086<h2><a name="DOM"></a><a name="Principles">DOM Principles</a></h2>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]3087
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]3088<p><a href="http://www.w3.org/DOM/">DOM</a> stands for the <em>Document
3089Object Model</em>; this is an API for accessing XML or HTML structured
3090documents. Native support for DOM in Gnome is on the way (module gnome-dom),
3091and will be based on gnome-xml. This will be a far cleaner interface to
3092manipulate XML files within Gnome since it won't expose the internal
3093structure.</p>
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]3094
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]3095<p>The current DOM implementation on top of libxml is the <a
Daniel Veillarda47fb3d2001-03-25 17:23:49 +0000[diff] [blame]3096href="http://cvs.gnome.org/lxr/source/gdome2/">gdome2 Gnome module</a>, this
3097is a full DOM interface, thanks to Paolo Casarini, check the <a
3098href="http://www.cs.unibo.it/~casarini/gdome2/">Gdome2 homepage</a> for more
3099informations.</p>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]3100
Daniel Veillard35008381999-10-25 13:15:52 +0000[diff] [blame]3101<h2><a name="Example"></a><a name="real">A real example</a></h2>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]3102
3103<p>Here is a real size example, where the actual content of the application
3104data 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]3105a proposal to keep a database of jobs related to Gnome, with an XML based
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]3106storage structure. Here is an <a href="gjobs.xml">XML encoded jobs
3107base</a>:</p>
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]3108<pre>&lt;?xml version="1.0"?&gt;
3109&lt;gjob:Helping xmlns:gjob="http://www.gnome.org/some-location"&gt;
3110 &lt;gjob:Jobs&gt;
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]3111
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]3112 &lt;gjob:Job&gt;
3113 &lt;gjob:Project ID="3"/&gt;
3114 &lt;gjob:Application&gt;GBackup&lt;/gjob:Application&gt;
3115 &lt;gjob:Category&gt;Development&lt;/gjob:Category&gt;
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]3116
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]3117 &lt;gjob:Update&gt;
3118 &lt;gjob:Status&gt;Open&lt;/gjob:Status&gt;
3119 &lt;gjob:Modified&gt;Mon, 07 Jun 1999 20:27:45 -0400 MET DST&lt;/gjob:Modified&gt;
3120 &lt;gjob:Salary&gt;USD 0.00&lt;/gjob:Salary&gt;
3121 &lt;/gjob:Update&gt;
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]3122
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]3123 &lt;gjob:Developers&gt;
3124 &lt;gjob:Developer&gt;
3125 &lt;/gjob:Developer&gt;
3126 &lt;/gjob:Developers&gt;
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]3127
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]3128 &lt;gjob:Contact&gt;
3129 &lt;gjob:Person&gt;Nathan Clemons&lt;/gjob:Person&gt;
3130 &lt;gjob:Email&gt;nathan@windsofstorm.net&lt;/gjob:Email&gt;
3131 &lt;gjob:Company&gt;
3132 &lt;/gjob:Company&gt;
3133 &lt;gjob:Organisation&gt;
3134 &lt;/gjob:Organisation&gt;
3135 &lt;gjob:Webpage&gt;
3136 &lt;/gjob:Webpage&gt;
3137 &lt;gjob:Snailmail&gt;
3138 &lt;/gjob:Snailmail&gt;
3139 &lt;gjob:Phone&gt;
3140 &lt;/gjob:Phone&gt;
3141 &lt;/gjob:Contact&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:Requirements&gt;
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]3144 The program should be released as free software, under the GPL.
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]3145 &lt;/gjob:Requirements&gt;
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]3146
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]3147 &lt;gjob:Skills&gt;
3148 &lt;/gjob:Skills&gt;
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]3149
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]3150 &lt;gjob:Details&gt;
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]3151 A GNOME based system that will allow a superuser to configure
3152 compressed and uncompressed files and/or file systems to be backed
3153 up with a supported media in the system. This should be able to
3154 perform via find commands generating a list of files that are passed
3155 to tar, dd, cpio, cp, gzip, etc., to be directed to the tape machine
3156 or via operations performed on the filesystem itself. Email
3157 notification and GUI status display very important.
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]3158 &lt;/gjob:Details&gt;
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]3159
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]3160 &lt;/gjob:Job&gt;
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]3161
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]3162 &lt;/gjob:Jobs&gt;
3163&lt;/gjob:Helping&gt;</pre>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]3164
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]3165<p>While loading the XML file into an internal DOM tree is a matter of
3166calling only a couple of functions, browsing the tree to gather the ata and
3167generate the internal structures is harder, and more error prone.</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]3168
3169<p>The suggested principle is to be tolerant with respect to the input
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]3170structure. For example, the ordering of the attributes is not significant,
3171the 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]3172depend on the order of the children of a given node, unless it really makes
3173things harder. Here is some code to parse the information for a person:</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]3174<pre>/*
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]3175 * A person record
3176 */
3177typedef struct person {
3178 char *name;
3179 char *email;
3180 char *company;
3181 char *organisation;
3182 char *smail;
3183 char *webPage;
3184 char *phone;
3185} person, *personPtr;
3186
3187/*
3188 * And the code needed to parse it
3189 */
3190personPtr parsePerson(xmlDocPtr doc, xmlNsPtr ns, xmlNodePtr cur) {
3191 personPtr ret = NULL;
3192
3193DEBUG("parsePerson\n");
3194 /*
3195 * allocate the struct
3196 */
3197 ret = (personPtr) malloc(sizeof(person));
3198 if (ret == NULL) {
3199 fprintf(stderr,"out of memory\n");
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]3200 return(NULL);
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]3201 }
3202 memset(ret, 0, sizeof(person));
3203
3204 /* We don't care what the top level element name is */
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]3205 cur = cur-&gt;xmlChildrenNode;
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]3206 while (cur != NULL) {
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]3207 if ((!strcmp(cur-&gt;name, "Person")) &amp;&amp; (cur-&gt;ns == ns))
3208 ret-&gt;name = xmlNodeListGetString(doc, cur-&gt;xmlChildrenNode, 1);
3209 if ((!strcmp(cur-&gt;name, "Email")) &amp;&amp; (cur-&gt;ns == ns))
3210 ret-&gt;email = xmlNodeListGetString(doc, cur-&gt;xmlChildrenNode, 1);
3211 cur = cur-&gt;next;
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]3212 }
3213
3214 return(ret);
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]3215}</pre>
3216
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]3217<p>Here are a couple of things to notice:</p>
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]3218<ul>
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]3219 <li>Usually a recursive parsing style is the more convenient one: XML data
3220 is by nature subject to repetitive constructs and usually exibits highly
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]3221 stuctured patterns.</li>
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]3222 <li>The two arguments of type <em>xmlDocPtr</em> and <em>xmlNsPtr</em>,
3223 i.e. the pointer to the global XML document and the namespace reserved to
3224 the application. Document wide information are needed for example to
3225 decode entities and it's a good coding practice to define a namespace for
3226 your application set of data and test that the element and attributes
3227 you're analyzing actually pertains to your application space. This is
3228 done by a simple equality test (cur-&gt;ns == ns).</li>
Daniel Veillardec70e912001-02-26 20:10:45 +0000[diff] [blame]3229 <li>To retrieve text and attributes value, you can use the function
3230 <em>xmlNodeListGetString</em> to gather all the text and entity reference
3231 nodes generated by the DOM output and produce an single text string.</li>
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]3232</ul>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]3233
3234<p>Here is another piece of code used to parse another level of the
3235structure:</p>
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]3236<pre>#include &lt;libxml/tree.h&gt;
Daniel Veillard361d8452000-04-03 19:48:13 +0000[diff] [blame]3237/*
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]3238 * a Description for a Job
3239 */
3240typedef struct job {
3241 char *projectID;
3242 char *application;
3243 char *category;
3244 personPtr contact;
3245 int nbDevelopers;
3246 personPtr developers[100]; /* using dynamic alloc is left as an exercise */
3247} job, *jobPtr;
3248
3249/*
3250 * And the code needed to parse it
3251 */
3252jobPtr parseJob(xmlDocPtr doc, xmlNsPtr ns, xmlNodePtr cur) {
3253 jobPtr ret = NULL;
3254
3255DEBUG("parseJob\n");
3256 /*
3257 * allocate the struct
3258 */
3259 ret = (jobPtr) malloc(sizeof(job));
3260 if (ret == NULL) {
3261 fprintf(stderr,"out of memory\n");
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]3262 return(NULL);
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]3263 }
3264 memset(ret, 0, sizeof(job));
3265
3266 /* We don't care what the top level element name is */
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]3267 cur = cur-&gt;xmlChildrenNode;
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]3268 while (cur != NULL) {
3269
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]3270 if ((!strcmp(cur-&gt;name, "Project")) &amp;&amp; (cur-&gt;ns == ns)) {
3271 ret-&gt;projectID = xmlGetProp(cur, "ID");
3272 if (ret-&gt;projectID == NULL) {
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]3273 fprintf(stderr, "Project has no ID\n");
3274 }
3275 }
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]3276 if ((!strcmp(cur-&gt;name, "Application")) &amp;&amp; (cur-&gt;ns == ns))
3277 ret-&gt;application = xmlNodeListGetString(doc, cur-&gt;xmlChildrenNode, 1);
3278 if ((!strcmp(cur-&gt;name, "Category")) &amp;&amp; (cur-&gt;ns == ns))
3279 ret-&gt;category = xmlNodeListGetString(doc, cur-&gt;xmlChildrenNode, 1);
3280 if ((!strcmp(cur-&gt;name, "Contact")) &amp;&amp; (cur-&gt;ns == ns))
3281 ret-&gt;contact = parsePerson(doc, ns, cur);
3282 cur = cur-&gt;next;
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]3283 }
3284
3285 return(ret);
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]3286}</pre>
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]3287
Daniel Veillardec70e912001-02-26 20:10:45 +0000[diff] [blame]3288<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]3289boring. Ultimately, it could be possble to write stubbers taking either C
3290data structure definitions, a set of XML examples or an XML DTD and produce
3291the code needed to import and export the content between C data and XML
3292storage. This is left as an exercise to the reader :-)</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]3293
Daniel Veillard6f0adb52000-07-03 11:41:26 +0000[diff] [blame]3294<p>Feel free to use <a href="example/gjobread.c">the code for the full C
3295parsing example</a> as a template, it is also available with Makefile in the
3296Gnome CVS base under gnome-xml/example</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]3297
Daniel Veillardc310d562000-06-23 18:32:15 +0000[diff] [blame]3298<h2><a name="Contributi">Contributions</a></h2>
3299<ul>
Daniel Veillardb8cfbd12001-10-25 10:53:28 +0000[diff] [blame]3300 <li>Bjorn Reese, William Brack and Thomas Broyer have provided a number of
3301 patches, Gary Pennington worked on the validation API, threading support
3302 and Solaris port.</li>
3303 <li>John Fleck helps maintaining the documentation and man pages.</li>
Daniel Veillardc6271d22001-10-27 07:50:58 +0000[diff] [blame]3304 <li><a href="mailto:ari@lusis.org">Ari Johnson</a>
Daniel Veillard51095312001-10-28 18:51:57 +0000[diff] [blame]3305 provides a C++ wrapper for libxml:<br>
Daniel Veillardc6271d22001-10-27 07:50:58 +0000[diff] [blame]3306 Website: <a
3307 href="http://lusis.org/~ari/xml++/">http://lusis.org/~ari/xml++/</a><br>
3308 Download: <a
Daniel Veillard51095312001-10-28 18:51:57 +0000[diff] [blame]3309 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]3310 <li><a href="mailto:izlatkovic@daenet.de">Igor Zlatkovic</a>
3311 is now the maintainer of the Windows port, <a
Daniel Veillard95189532001-07-26 18:30:26 +0000[diff] [blame]3312 href="http://www.fh-frankfurt.de/~igor/projects/libxml/index.html">he
3313 provides binaries</a></li>
Daniel Veillardc9484202001-10-24 12:35:52 +0000[diff] [blame]3314 <li><a href="mailto:Gary.Pennington@sun.com">Gary Pennington</a>
Daniel Veillarddb9dfd92001-11-26 17:25:02 +0000[diff] [blame]3315 provides <a href="http://garypennington.net/libxml2/">Solaris
Daniel Veillard0a702dc2001-10-19 14:50:57 +0000[diff] [blame]3316 binaries</a></li>
Daniel Veillarde356c282001-03-10 12:32:04 +0000[diff] [blame]3317 <li><a
3318 href="http://mail.gnome.org/archives/xml/2001-March/msg00014.html">Matt
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]3319 Sergeant</a>
3320 developped <a href="http://axkit.org/download/">XML::LibXSLT</a>, a perl
3321 wrapper for libxml2/libxslt as part of the <a
3322 href="http://axkit.com/">AxKit XML application server</a></li>
3323 <li><a href="mailto:fnatter@gmx.net">Felix Natter</a>
3324 and <a href="mailto:geertk@ai.rug.nl">Geert Kloosterman</a> provide <a
Daniel Veillardca989762001-06-23 17:39:29 +0000[diff] [blame]3325 href="libxml-doc.el">an emacs module</a> to lookup libxml(2) functions
Daniel Veillard3f6f7f62000-06-30 17:58:25 +0000[diff] [blame]3326 documentation</li>
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]3327 <li><a href="mailto:sherwin@nlm.nih.gov">Ziying Sherwin</a>
3328 provided <a href="http://xmlsoft.org/messages/0488.html">man
3329 pages</a></li>
Daniel Veillard5168dbf2001-07-07 00:18:23 +0000[diff] [blame]3330 <li>there is a module for <a
3331 href="http://acs-misc.sourceforge.net/nsxml.html">libxml/libxslt support
3332 in OpenNSD/AOLServer</a></li>
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]3333 <li><a href="mailto:dkuhlman@cutter.rexx.com">Dave Kuhlman</a>
3334 provides libxml/libxslt <a href="http://www.rexx.com/~dkuhlman">wrappers
3335 for Python</a></li>
Daniel Veillard1aadc442001-11-28 13:10:32 +0000[diff] [blame]3336 <li>Petr Kozelka provides <a
3337 href="http://sourceforge.net/projects/libxml2-pas">Pascal units to glue
3338 libxml2</a> with Kylix and Delphi and other Pascal compilers</li>
Daniel Veillardc310d562000-06-23 18:32:15 +0000[diff] [blame]3339</ul>
3340
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]3341<p></p>
Daniel Veillardccb09631998-10-27 06:21:04 +0000[diff] [blame]3342</body>
3343</html>