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gerrit-public.fairphone.software / platform / external / libxml2 / 306be999e9f0c1c5d963a5cd6b1b763b6ede4e07 / . / doc / xml.html
blob: 543a0494821e84db16e7106483dc38b15ac4afdf [file] [log] [blame]
Daniel Veillardccb09631998-10-27 06:21:04 +0000[diff] [blame]1<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN"
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2 "http://www.w3.org/TR/REC-html40/loose.dtd">
Daniel Veillardccb09631998-10-27 06:21:04 +0000[diff] [blame]3<html>
4<head>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]5 <title>The XML library for Gnome</title>
Daniel Veillard306be992000-07-03 12:38:45 +0000[diff] [blame^]6 <meta name="GENERATOR" content="amaya V3.1">
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 Veillardec303412000-03-24 13:41:54 +0000[diff] [blame]11<p><a href="http://www.gnome.org/"><img src="smallfootonly.gif" alt="Gnome
12Logo"></a><a href="http://www.w3.org/Status"><img src="w3c.png" alt="W3C
13Logo"></a></p>
14
Daniel Veillardccb09631998-10-27 06:21:04 +0000[diff] [blame]15<h1 align="center">The XML library for Gnome</h1>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]16
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]17<h2 style="text-align: center">libxml, a.k.a. gnome-xml</h2>
18
19<p></p>
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]20<ul>
21 <li><a href="#Introducti">Introduction</a></li>
22 <li><a href="#Documentat">Documentation</a></li>
Daniel Veillard10a2c651999-12-12 13:03:50 +0000[diff] [blame]23 <li><a href="#Downloads">Downloads</a></li>
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]24 <li><a href="#News">News</a></li>
25 <li><a href="#XML">XML</a></li>
26 <li><a href="#tree">The tree output</a></li>
27 <li><a href="#interface">The SAX interface</a></li>
28 <li><a href="#library">The XML library interfaces</a>
29 <ul>
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]30 <li><a href="#Invoking">Invoking the parser: the pull way</a></li>
31 <li><a href="#Invoking">Invoking the parser: the push way</a></li>
32 <li><a href="#Invoking2">Invoking the parser: the SAX interface</a></li>
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]33 <li><a href="#Building">Building a tree from scratch</a></li>
34 <li><a href="#Traversing">Traversing the tree</a></li>
35 <li><a href="#Modifying">Modifying the tree</a></li>
36 <li><a href="#Saving">Saving the tree</a></li>
37 <li><a href="#Compressio">Compression</a></li>
38 </ul>
39 </li>
40 <li><a href="#Entities">Entities or no entities</a></li>
41 <li><a href="#Namespaces">Namespaces</a></li>
42 <li><a href="#Validation">Validation</a></li>
43 <li><a href="#Principles">DOM principles</a></li>
44 <li><a href="#real">A real example</a></li>
Daniel Veillardc310d562000-06-23 18:32:15 +0000[diff] [blame]45 <li><a href="#Contributi">Contribution</a></li>
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]46</ul>
47
48<h2><a name="Introducti">Introduction</a></h2>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]49
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]50<p>This document describes libxml, the <a
51href="http://www.w3.org/XML/">XML</a> library provided in the <a
52href="http://www.gnome.org/">Gnome</a> framework. XML is a standard for
53building tag-based structured documents/data.</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]54
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]55<p>Here are some key points about libxml:</p>
56<ul>
Daniel Veillard6f0adb52000-07-03 11:41:26 +0000[diff] [blame]57 <li>It is written in plain C, making as few assumptions as possible and
58 sticking closely to ANSI C for easy embedding.</li>
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]59 <li>The internal document repesentation is as close as possible to the <a
60 href="http://www.w3.org/DOM/">DOM</a> interfaces.</li>
61 <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]62 like interface</a>; the interface is designed to be compatible with <a
63 href="http://www.jclark.com/xml/expat.html">Expat</a>.</li>
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]64 <li>Libxml now includes a nearly complete <a
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]65 href="http://www.w3.org/TR/xpath">XPath</a> implementation.</li>
Daniel Veillard402e8c82000-02-29 22:57:47 +0000[diff] [blame]66 <li>Libxml exports Push and Pull type parser interfaces for both XML and
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]67 HTML.</li>
Daniel Veillardec303412000-03-24 13:41:54 +0000[diff] [blame]68 <li>This library is released both under the <a
69 href="http://www.w3.org/Consortium/Legal/copyright-software-19980720.html">W3C
70 IPR</a> and the GNU LGPL. Use either at your convenience, basically this
71 should make everybody happy, if not, drop me a mail.</li>
Daniel Veillardc310d562000-06-23 18:32:15 +0000[diff] [blame]72 <li>There is <a href="upgrade.html">a first set of instructions</a>
Daniel Veillardedfb29b2000-03-14 19:59:05 +0000[diff] [blame]73 concerning upgrade from libxml-1.x to libxml-2.x</li>
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]74</ul>
Daniel Veillardccb09631998-10-27 06:21:04 +0000[diff] [blame]75
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]76<h2><a name="Documentat">Documentation</a></h2>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]77
Daniel Veillard402e8c82000-02-29 22:57:47 +0000[diff] [blame]78<p>There are some on-line resources about using libxml:</p>
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]79<ol>
Daniel Veillard365e13b2000-07-02 07:56:37 +0000[diff] [blame]80 <li>Check the <a href="FAQ.html">FAQ</a></li>
Daniel Veillardc19fccc2000-07-03 11:52:01 +0000[diff] [blame]81 <li>Check the <a href="http://xmlsoft.org/html/libxml-lib.html">extensive
Daniel Veillard365e13b2000-07-02 07:56:37 +0000[diff] [blame]82 documentation</a> automatically extracted from code comments.</li>
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]83 <li>This page provides a global overview and <a href="#real">some
Daniel Veillard402e8c82000-02-29 22:57:47 +0000[diff] [blame]84 examples</a> on how to use libxml.</li>
85 <li><a href="mailto:james@daa.com.au">James Henstridge</a> wrote <a
86 href="http://www.daa.com.au/~james/gnome/xml-sax/xml-sax.html">some nice
87 documentation</a> explaining how to use the libxml SAX interface.</li>
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]88 <li>George Lebl wrote <a
89 href="http://www-4.ibm.com/software/developer/library/gnome3/">an article
Daniel Veillard402e8c82000-02-29 22:57:47 +0000[diff] [blame]90 for IBM developerWorks</a> about using libxml.</li>
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]91 <li>It is also a good idea to check to <a href="mailto:raph@levien.com">Raph
92 Levien</a> <a href="http://levien.com/gnome/">web site</a> since he is
93 building the <a href="http://levien.com/gnome/gdome.html">DOM interface
Daniel Veillard402e8c82000-02-29 22:57:47 +0000[diff] [blame]94 gdome</a> on top of libxml result tree and an implementation of <a
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]95 href="http://www.w3.org/Graphics/SVG/">SVG</a> called <a
96 href="http://www.levien.com/svg/">gill</a>. Check his <a
97 href="http://www.levien.com/gnome/domination.html">DOMination
98 paper</a>.</li>
Daniel Veillardec303412000-03-24 13:41:54 +0000[diff] [blame]99 <li>Check <a href="http://cvs.gnome.org/lxr/source/gnome-xml/TODO">the TODO
100 file</a></li>
101 <li>Read the <a href="upgrade.html">1.x to 2.x upgrade path</a>. If you are
102 starting a new project using libxml you should really use the 2.x
103 version.</li>
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]104 <li>And don't forget to look at the <a href="/messages/">mailing-list
Daniel Veillardc310d562000-06-23 18:32:15 +0000[diff] [blame]105 archive</a>.</li>
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]106</ol>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]107
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]108<h3>Reporting bugs and getting help</h3>
Daniel Veillard4c3a2031999-11-19 17:46:26 +0000[diff] [blame]109
Daniel Veillard402e8c82000-02-29 22:57:47 +0000[diff] [blame]110<p>Well, bugs or missing features are always possible, and I will make a point
111of fixing them in a timely fashion. The best way to report a bug is to <a
Daniel Veillard4c3a2031999-11-19 17:46:26 +0000[diff] [blame]112href="http://bugs.gnome.org/db/pa/lgnome-xml.html">use the Gnome bug tracking
Daniel Veillard402e8c82000-02-29 22:57:47 +0000[diff] [blame]113database</a>. I look at reports there regularly and it's good to have a
Daniel Veillard4c3a2031999-11-19 17:46:26 +0000[diff] [blame]114reminder when a bug is still open. Check the <a
115href="http://bugs.gnome.org/Reporting.html">instructions on reporting bugs</a>
Daniel Veillard402e8c82000-02-29 22:57:47 +0000[diff] [blame]116and be sure to specify that the bug is for the package gnome-xml.</p>
Daniel Veillard4c3a2031999-11-19 17:46:26 +0000[diff] [blame]117
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]118<p>There is also a mailing-list <a
119href="mailto:xml@rufus.w3.org">xml@rufus.w3.org</a> for libxml, with an <a
120href="http://xmlsoft.org/messages">on-line archive</a>. To subscribe to this
Daniel Veillard402e8c82000-02-29 22:57:47 +0000[diff] [blame]121majordomo based list, send a mail message to <a
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]122href="mailto:majordomo@rufus.w3.org">majordomo@rufus.w3.org</a> with
123"subscribe xml" in the <strong>content</strong> of the message.</p>
124
Daniel Veillard402e8c82000-02-29 22:57:47 +0000[diff] [blame]125<p>Alternatively, you can just send the bug to the <a
Daniel Veillard10a2c651999-12-12 13:03:50 +0000[diff] [blame]126href="mailto:xml@rufus.w3.org">xml@rufus.w3.org</a> list.</p>
Daniel Veillard4c3a2031999-11-19 17:46:26 +0000[diff] [blame]127
Daniel Veillardec303412000-03-24 13:41:54 +0000[diff] [blame]128<p>Of course, bugs reports with a suggested patch for fixing them will
129probably be processed faster.</p>
130
131<p>If you're looking for help, a quick look at <a
132href="http://xmlsoft.org/messages/#407">the list archive</a> may actually
133provide the answer, I usually send source samples when answering libxml usage
Daniel Veillard6f0adb52000-07-03 11:41:26 +0000[diff] [blame]134questions. The <a href="http://xmlsoft.org/html/book1.html">auto-generated
Daniel Veillardec303412000-03-24 13:41:54 +0000[diff] [blame]135documentantion</a> is not as polished as I would like (i need to learn more
136about Docbook), but it's a good starting point.</p>
137
Daniel Veillard10a2c651999-12-12 13:03:50 +0000[diff] [blame]138<h2><a name="Downloads">Downloads</a></h2>
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]139
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]140<p>The latest versions of libxml can be found on <a
Daniel Veillard6c8b1172000-03-01 00:40:41 +0000[diff] [blame]141href="ftp://rpmfind.net/pub/libxml/">rpmfind.net</a> or on the <a
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]142href="ftp://ftp.gnome.org/pub/GNOME/MIRRORS.html">Gnome FTP server</a> either
Daniel Veillard10a2c651999-12-12 13:03:50 +0000[diff] [blame]143as a <a href="ftp://ftp.gnome.org/pub/GNOME/stable/sources/libxml/">source
Daniel Veillard306be992000-07-03 12:38:45 +0000[diff] [blame^]144archive</a> or <a
145href="ftp://ftp.gnome.org/pub/GNOME/contrib/redhat/SRPMS/">RPM packages</a>.
146(NOTE that you need both the <a
Daniel Veillardc19fccc2000-07-03 11:52:01 +0000[diff] [blame]147href="http://rpmfind.net/linux/RPM/libxml2.html">libxml(2)</a> and <a
148href="http://rpmfind.net/linux/RPM/libxml2-devel.html">libxml(2)-devel</a>
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]149packages installed to compile applications using libxml.)</p>
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]150
Daniel Veillard6c8b1172000-03-01 00:40:41 +0000[diff] [blame]151<p><a name="Snapshot">Snapshot:</a></p>
152<ul>
153 <li>Code from the W3C cvs base libxml <a
154 href="ftp://rpmfind.net/pub/libxml/cvs-snapshot.tar.gz">cvs-snapshot.tar.gz</a></li>
155 <li>Docs, content of the web site, the list archive included <a
156 href="ftp://rpmfind.net/pub/libxml/libxml-docs.tar.gz">libxml-docs.tar.gz</a></li>
157</ul>
158
159<p><a name="Contribs">Contribs:</a></p>
160
161<p>I do accept external contributions, especially if compiling on another
162platform, get in touch with me to upload the package. I will keep them in the
163<a href="ftp://rpmfind.net/pub/libxml/contribs/">contrib directory</a></p>
164
Daniel Veillardc310d562000-06-23 18:32:15 +0000[diff] [blame]165<p>Libxml is also available from 2 CVS bases:</p>
Daniel Veillard10a2c651999-12-12 13:03:50 +0000[diff] [blame]166<ul>
167 <li><p>The <a href="http://dev.w3.org/cvsweb/XML/">W3C CVS base</a>,
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]168 available read-only using the CVS pserver authentification (I tend to use
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]169 this base for my own development, so it's updated more regularly, but the
170 content may not be as stable):</p>
Daniel Veillard10a2c651999-12-12 13:03:50 +0000[diff] [blame]171 <pre>CVSROOT=:pserver:anonymous@dev.w3.org:/sources/public
Daniel Veillard365e13b2000-07-02 07:56:37 +0000[diff] [blame]172 password: anonymous
173 module: XML</pre>
Daniel Veillard10a2c651999-12-12 13:03:50 +0000[diff] [blame]174 </li>
175 <li><p>The <a
176 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]177 CVS base</a>. Check the <a
178 href="http://developer.gnome.org/tools/cvs.html">Gnome CVS Tools</a> page;
179 the CVS module is <b>gnome-xml</b>.</p>
Daniel Veillard10a2c651999-12-12 13:03:50 +0000[diff] [blame]180 </li>
181</ul>
182
183<h2><a name="News">News</a></h2>
184
Daniel Veillard944b5ff1999-12-15 19:08:24 +0000[diff] [blame]185<h3>CVS only : check the <a
186href="http://cvs.gnome.org/lxr/source/gnome-xml/ChangeLog">Changelog</a> file
187for really accurate description</h3>
Daniel Veillard4c3a2031999-11-19 17:46:26 +0000[diff] [blame]188<ul>
Daniel Veillard10a2c651999-12-12 13:03:50 +0000[diff] [blame]189 <li>working on HTML and XML links recognition layers, get in touch with me
Daniel Veillard944b5ff1999-12-15 19:08:24 +0000[diff] [blame]190 if you want to test those.</li>
Daniel Veillard361d8452000-04-03 19:48:13 +0000[diff] [blame]191</ul>
192
Daniel Veillard3f6f7f62000-06-30 17:58:25 +0000[diff] [blame]193<h3>2.1.0 and 1.8.8: June 29 2000</h3>
194<ul>
195 <li>1.8.8 is mostly a comodity package for upgrading to libxml2 accoding to
196 <a href="upgrade.html">new instructions</a>. It fixes a nasty problem
197 about &amp;#38; charref parsing</li>
198 <li>2.1.0 also ease the upgrade from libxml v1 to the recent version. it
199 also contains numerous fixes and enhancements:
200 <ul>
201 <li>added xmlStopParser() to stop parsing</li>
202 <li>improved a lot parsing speed when there is large CDATA blocs</li>
203 <li>includes XPath patches provided by Picdar Technology</li>
204 <li>tried to fix as much as possible DtD validation and namespace
205 related problems</li>
206 <li>output to a given encoding has been added/tested</li>
207 <li>lot of various fixes</li>
208 </ul>
209 </li>
210</ul>
211
Daniel Veillarde0aed302000-04-16 08:52:20 +0000[diff] [blame]212<h3>2.0.0: Apr 12 2000</h3>
Daniel Veillard361d8452000-04-03 19:48:13 +0000[diff] [blame]213<ul>
214 <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]215 idea to check the 1.x to 2.x upgrade instructions. NOTE: while initally
216 scheduled for Apr 3 the relase occured only on Apr 12 due to massive
217 workload.</li>
Daniel Veillard361d8452000-04-03 19:48:13 +0000[diff] [blame]218 <li>The include are now located under $prefix/include/libxml (instead of
Daniel Veillarde0aed302000-04-16 08:52:20 +0000[diff] [blame]219 $prefix/include/gnome-xml), they also are referenced by
Daniel Veillard361d8452000-04-03 19:48:13 +0000[diff] [blame]220 <pre>#include &lt;libxml/xxx.h></pre>
Daniel Veillarde0aed302000-04-16 08:52:20 +0000[diff] [blame]221 <p>instead of</p>
Daniel Veillard361d8452000-04-03 19:48:13 +0000[diff] [blame]222 <pre>#include "xxx.h"</pre>
223 </li>
Daniel Veillard8f621982000-03-20 13:07:15 +0000[diff] [blame]224 <li>a new URI module for parsing URIs and following strictly RFC 2396</li>
225 <li>the memory allocation routines used by libxml can now be overloaded
226 dynamically by using xmlMemSetup()</li>
Daniel Veillard361d8452000-04-03 19:48:13 +0000[diff] [blame]227 <li>The previously CVS only tool tester has been renamed
228 <strong>xmllint</strong> and is now installed as part of the libxml2
229 package</li>
Daniel Veillarde0aed302000-04-16 08:52:20 +0000[diff] [blame]230 <li>The I/O interface has been revamped. There is now ways to plug in
231 specific I/O modules, either at the URI scheme detection level using
232 xmlRegisterInputCallbacks() or by passing I/O functions when creating a
233 parser context using xmlCreateIOParserCtxt()</li>
234 <li>there is a C preprocessor macro LIBXML_VERSION providing the version
235 number of the libxml module in use</li>
236 <li>a number of optional features of libxml can now be excluded at configure
237 time (FTP/HTTP/HTML/XPath/Debug)</li>
Daniel Veillardedfb29b2000-03-14 19:59:05 +0000[diff] [blame]238</ul>
239
240<h3>2.0.0beta: Mar 14 2000</h3>
241<ul>
242 <li>This is a first Beta release of libxml version 2</li>
243 <li>It's available only from<a href="ftp://rpmfind.net/pub/libxml/">
244 rpmfind.net FTP</a>, it's packaged as libxml2-2.0.0beta and available as
245 tar and RPMs</li>
246 <li>This version is now the head in the Gnome CVS base, the old one is
247 available under the tag LIB_XML_1_X</li>
248 <li>This includes a very large set of changes. Froma programmatic point of
249 view applications should not have to be modified too much, check the <a
250 href="upgrade.html">upgrade page</a></li>
251 <li>Some interfaces may changes (especially a bit about encoding).</li>
252 <li>the updates includes:
Daniel Veillard6c8b1172000-03-01 00:40:41 +0000[diff] [blame]253 <ul>
Daniel Veillardedfb29b2000-03-14 19:59:05 +0000[diff] [blame]254 <li>fix I18N support. ISO-Latin-x/UTF-8/UTF-16 (nearly) seems correctly
255 handled now</li>
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]256 <li>Better handling of entities, especially well formedness checking and
257 proper PEref extensions in external subsets</li>
Daniel Veillard6c8b1172000-03-01 00:40:41 +0000[diff] [blame]258 <li>DTD conditional sections</li>
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]259 <li>Validation now correcly handle entities content</li>
Daniel Veillard6c8b1172000-03-01 00:40:41 +0000[diff] [blame]260 <li><a href="http://rpmfind.net/tools/gdome/messages/0039.html">change
261 structures to accomodate DOM</a></li>
Daniel Veillard6c8b1172000-03-01 00:40:41 +0000[diff] [blame]262 </ul>
263 </li>
Daniel Veillardedfb29b2000-03-14 19:59:05 +0000[diff] [blame]264 <li>Serious progress were made toward compliance, <a
265 href="conf/result.html">here are the result of the test</a> against the
266 OASIS testsuite (except the japanese tests since I don't support that
267 encoding yet). This URL is rebuilt every couple of hours using the CVS
268 head version.</li>
Daniel Veillarde41f2b72000-01-30 20:00:07 +0000[diff] [blame]269</ul>
270
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]271<h3>1.8.7: Mar 6 2000</h3>
272<ul>
273 <li>This is a bug fix release:</li>
274 <li>It is possible to disable the ignorable blanks heuristic used by
275 libxml-1.x, a new function xmlKeepBlanksDefault(0) will allow this. Note
276 that for adherence to XML spec, this behaviour will be disabled by default
277 in 2.x . The same function will allow to keep compatibility for old
278 code.</li>
279 <li>Blanks in &lt;a> &lt;/a> constructs are not ignored anymore, avoiding
280 heuristic is really the Right Way :-\</li>
281 <li>The unchecked use of snprintf which was breaking libxml-1.8.6
282 compilation on some platforms has been fixed</li>
283 <li>nanoftp.c nanohttp.c: Fixed '#' and '?' stripping when processing
284 URIs</li>
285</ul>
286
Daniel Veillarde41f2b72000-01-30 20:00:07 +0000[diff] [blame]287<h3>1.8.6: Jan 31 2000</h3>
288<ul>
289 <li>added a nanoFTP transport module, debugged until the new version of <a
290 href="http://rpmfind.net/linux/rpm2html/rpmfind.html">rpmfind</a> can use
291 it without troubles</li>
Daniel Veillardda07c342000-01-25 18:31:22 +0000[diff] [blame]292</ul>
293
294<h3>1.8.5: Jan 21 2000</h3>
295<ul>
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]296 <li>adding APIs to parse a well balanced chunk of XML (production <a
297 href="http://www.w3.org/TR/REC-xml#NT-content">[43] content</a> of the XML
298 spec)</li>
Daniel Veillard461a66c2000-01-18 18:01:01 +0000[diff] [blame]299 <li>fixed a hideous bug in xmlGetProp pointed by Rune.Djurhuus@fast.no</li>
300 <li>Jody Goldberg &lt;jgoldberg@home.com> provided another patch trying to
301 solve the zlib checks problems</li>
302 <li>The current state in gnome CVS base is expected to ship as 1.8.5 with
303 gnumeric soon</li>
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]304</ul>
305
306<h3>1.8.4: Jan 13 2000</h3>
307<ul>
308 <li>bug fixes, reintroduced xmlNewGlobalNs(), fixed xmlNewNs()</li>
309 <li>all exit() call should have been removed from libxml</li>
310 <li>fixed a problem with INCLUDE_WINSOCK on WIN32 platform</li>
311 <li>added newDocFragment()</li>
Daniel Veillardf84f71f2000-01-05 19:54:23 +0000[diff] [blame]312</ul>
313
314<h3>1.8.3: Jan 5 2000</h3>
315<ul>
316 <li>a Push interface for the XML and HTML parsers</li>
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]317 <li>a shell-like interface to the document tree (try tester --shell :-)</li>
Daniel Veillarddbfd6411999-12-28 16:35:14 +0000[diff] [blame]318 <li>lots of bug fixes and improvement added over XMas hollidays</li>
Daniel Veillard437b87b2000-01-03 17:30:46 +0000[diff] [blame]319 <li>fixed the DTD parsing code to work with the xhtml DTD</li>
Daniel Veillardf84f71f2000-01-05 19:54:23 +0000[diff] [blame]320 <li>added xmlRemoveProp(), xmlRemoveID() and xmlRemoveRef()</li>
321 <li>Fixed bugs in xmlNewNs()</li>
Daniel Veillard437b87b2000-01-03 17:30:46 +0000[diff] [blame]322 <li>External entity loading code has been revamped, now it uses
Daniel Veillardf84f71f2000-01-05 19:54:23 +0000[diff] [blame]323 xmlLoadExternalEntity(), some fix on entities processing were added</li>
Daniel Veillard437b87b2000-01-03 17:30:46 +0000[diff] [blame]324 <li>cleaned up WIN32 includes of socket stuff</li>
Daniel Veillard5cb5ab81999-12-21 15:35:29 +0000[diff] [blame]325</ul>
326
327<h3>1.8.2: Dec 21 1999</h3>
328<ul>
Daniel Veillardb24054a1999-12-18 15:32:46 +0000[diff] [blame]329 <li>I got another problem with includes and C++, I hope this issue is fixed
330 for good this time</li>
Daniel Veillard5cb5ab81999-12-21 15:35:29 +0000[diff] [blame]331 <li>Added a few tree modification functions: xmlReplaceNode,
332 xmlAddPrevSibling, xmlAddNextSibling, xmlNodeSetName and
333 xmlDocSetRootElement</li>
334 <li>Tried to improve the HTML output with help from <a
335 href="mailto:clahey@umich.edu">Chris Lahey</a></li>
Daniel Veillarde4e51311999-12-18 15:32:46 +0000[diff] [blame]336</ul>
Daniel Veillardb24054a1999-12-18 15:32:46 +0000[diff] [blame]337
Daniel Veillarde4e51311999-12-18 15:32:46 +0000[diff] [blame]338<h3>1.8.1: Dec 18 1999</h3>
339<ul>
340 <li>various patches to avoid troubles when using libxml with C++ compilers
341 the "namespace" keyword and C escaping in include files</li>
342 <li>a problem in one of the core macros IS_CHAR was corrected</li>
343 <li>fixed a bug introduced in 1.8.0 breaking default namespace processing,
344 and more specifically the Dia application</li>
Daniel Veillard944b5ff1999-12-15 19:08:24 +0000[diff] [blame]345 <li>fixed a posteriori validation (validation after parsing, or by using a
346 Dtd not specified in the original document)</li>
Daniel Veillardb24054a1999-12-18 15:32:46 +0000[diff] [blame]347 <li>fixed a bug in</li>
Daniel Veillard10a2c651999-12-12 13:03:50 +0000[diff] [blame]348</ul>
349
350<h3>1.8.0: Dec 12 1999</h3>
351<ul>
352 <li>cleanup, especially memory wise</li>
353 <li>the parser should be more reliable, especially the HTML one, it should
354 not crash, whatever the input !</li>
355 <li>Integrated various patches, especially a speedup improvement for large
356 dataset from <a href="mailto:cnygard@bellatlantic.net">Carl Nygard</a>,
357 configure with --with-buffers to enable them.</li>
358 <li>attribute normalization, oops should have been added long ago !</li>
359 <li>attributes defaulted from Dtds should be available, xmlSetProp() now
360 does entities escapting by default.</li>
Daniel Veillard4c3a2031999-11-19 17:46:26 +0000[diff] [blame]361</ul>
Daniel Veillard35008381999-10-25 13:15:52 +0000[diff] [blame]362
363<h3>1.7.4: Oct 25 1999</h3>
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]364<ul>
Daniel Veillard35008381999-10-25 13:15:52 +0000[diff] [blame]365 <li>Lots of HTML improvement</li>
366 <li>Fixed some errors when saving both XML and HTML</li>
367 <li>More examples, the regression tests should now look clean</li>
368 <li>Fixed a bug with contiguous charref</li>
369</ul>
370
371<h3>1.7.3: Sep 29 1999</h3>
372<ul>
373 <li>portability problems fixed</li>
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]374 <li>snprintf was used unconditionnally, leading to link problems on system
Daniel Veillard35008381999-10-25 13:15:52 +0000[diff] [blame]375 were it's not available, fixed</li>
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]376</ul>
377
378<h3>1.7.1: Sep 24 1999</h3>
379<ul>
380 <li>The basic type for strings manipulated by libxml has been renamed in
381 1.7.1 from <strong>CHAR</strong> to <strong>xmlChar</strong>. The reason
382 is that CHAR was conflicting with a predefined type on Windows. However on
383 non WIN32 environment, compatibility is provided by the way of a
384 <strong>#define </strong>.</li>
385 <li>Changed another error : the use of a structure field called errno, and
386 leading to troubles on platforms where it's a macro</li>
387</ul>
388
389<h3>1.7.0: sep 23 1999</h3>
390<ul>
391 <li>Added the ability to fetch remote DTD or parsed entities, see the <a
Daniel Veillardc19fccc2000-07-03 11:52:01 +0000[diff] [blame]392 href="html/gnome-xml-nanohttp.html">nanohttp</a> module.</li>
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]393 <li>Added an errno to report errors by another mean than a simple printf
394 like callback</li>
395 <li>Finished ID/IDREF support and checking when validation</li>
396 <li>Serious memory leaks fixed (there is now a <a
Daniel Veillardc19fccc2000-07-03 11:52:01 +0000[diff] [blame]397 href="html/gnome-xml-xmlmemory.html">memory wrapper</a> module)</li>
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]398 <li>Improvement of <a href="http://www.w3.org/TR/xpath">XPath</a>
399 implementation</li>
400 <li>Added an HTML parser front-end</li>
401</ul>
402
403<h2><a name="XML">XML</a></h2>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]404
Daniel Veillard402e8c82000-02-29 22:57:47 +0000[diff] [blame]405<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]406markup-based structured documents. Here is <a name="example">an example XML
407document</a>:</p>
Daniel Veillardccb09631998-10-27 06:21:04 +0000[diff] [blame]408<pre>&lt;?xml version="1.0"?>
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]409&lt;EXAMPLE prop1="gnome is great" prop2="&amp;amp; linux too">
Daniel Veillardccb09631998-10-27 06:21:04 +0000[diff] [blame]410 &lt;head>
411 &lt;title>Welcome to Gnome&lt;/title>
412 &lt;/head>
413 &lt;chapter>
414 &lt;title>The Linux adventure&lt;/title>
415 &lt;p>bla bla bla ...&lt;/p>
416 &lt;image href="linus.gif"/>
417 &lt;p>...&lt;/p>
418 &lt;/chapter>
419&lt;/EXAMPLE></pre>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]420
Daniel Veillard402e8c82000-02-29 22:57:47 +0000[diff] [blame]421<p>The first line specifies that it's an XML document and gives useful
422information about its encoding. Then the document is a text format whose
423structure is specified by tags between brackets. <strong>Each tag opened has
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]424to be closed</strong>. XML is pedantic about this. However, if a tag is empty
425(no content), a single tag can serve as both the opening and closing tag if it
426ends with <code>/></code> rather than with <code>></code>. Note that, for
427example, the image tag has no content (just an attribute) and is closed by
428ending the tag with <code>/></code>.</p>
Daniel Veillardccb09631998-10-27 06:21:04 +0000[diff] [blame]429
Daniel Veillard402e8c82000-02-29 22:57:47 +0000[diff] [blame]430<p>XML can be applied sucessfully to a wide range of uses, from long term
431structured document maintenance (where it follows the steps of SGML) to simple
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]432data encoding mechanisms like configuration file formatting (glade),
433spreadsheets (gnumeric), or even shorter lived documents such as WebDAV where
434it is used to encode remote calls between a client and a server.</p>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]435
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]436<h2><a name="tree">The tree output</a></h2>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]437
438<p>The parser returns a tree built during the document analysis. The value
Daniel Veillard402e8c82000-02-29 22:57:47 +0000[diff] [blame]439returned is an <strong>xmlDocPtr</strong> (i.e., a pointer to an
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]440<strong>xmlDoc</strong> structure). This structure contains information such
Daniel Veillard306be992000-07-03 12:38:45 +0000[diff] [blame^]441as the file name, the document type, and a <strong>children</strong> pointer
442which is the root of the document (or more exactly the first child under the
443root which is the document). The tree is made of <strong>xmlNode</strong>s,
444chained in double-linked lists of siblings and with children&lt;->parent
445relationship. An xmlNode can also carry properties (a chain of xmlAttr
446structures). An attribute may have a value which is a list of TEXT or
447ENTITY_REF nodes.</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]448
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]449<p>Here is an example (erroneous with respect to the XML spec since there
450should be only one ELEMENT under the root):</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]451
452<p><img src="structure.gif" alt=" structure.gif "></p>
453
454<p>In the source package there is a small program (not installed by default)
Daniel Veillard361d8452000-04-03 19:48:13 +0000[diff] [blame]455called <strong>xmllint</strong> which parses XML files given as argument and
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]456prints them back as parsed. This is useful for detecting errors both in XML
457code and in the XML parser itself. It has an option <strong>--debug</strong>
458which prints the actual in-memory structure of the document, here is the
459result with the <a href="#example">example</a> given before:</p>
Daniel Veillard10c6a8f1998-10-28 01:00:12 +0000[diff] [blame]460<pre>DOCUMENT
461version=1.0
462standalone=true
463 ELEMENT EXAMPLE
464 ATTRIBUTE prop1
465 TEXT
466 content=gnome is great
467 ATTRIBUTE prop2
468 ENTITY_REF
469 TEXT
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]470 content= linux too
Daniel Veillard402e8c82000-02-29 22:57:47 +0000[diff] [blame]471 ELEMENT head
Daniel Veillard10c6a8f1998-10-28 01:00:12 +0000[diff] [blame]472 ELEMENT title
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]473 TEXT
474 content=Welcome to Gnome
Daniel Veillard10c6a8f1998-10-28 01:00:12 +0000[diff] [blame]475 ELEMENT chapter
476 ELEMENT title
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]477 TEXT
478 content=The Linux adventure
Daniel Veillard10c6a8f1998-10-28 01:00:12 +0000[diff] [blame]479 ELEMENT p
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]480 TEXT
481 content=bla bla bla ...
Daniel Veillard10c6a8f1998-10-28 01:00:12 +0000[diff] [blame]482 ELEMENT image
483 ATTRIBUTE href
484 TEXT
485 content=linus.gif
486 ELEMENT p
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]487 TEXT
488 content=...</pre>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]489
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]490<p>This should be useful for learning the internal representation model.</p>
Daniel Veillardccb09631998-10-27 06:21:04 +0000[diff] [blame]491
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]492<h2><a name="interface">The SAX interface</a></h2>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]493
Daniel Veillard402e8c82000-02-29 22:57:47 +0000[diff] [blame]494<p>Sometimes the DOM tree output is just too large to fit reasonably into
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]495memory. In that case (and if you don't expect to save back the XML document
496loaded using libxml), it's better to use the SAX interface of libxml. SAX is a
Daniel Veillard402e8c82000-02-29 22:57:47 +0000[diff] [blame]497<strong>callback-based interface</strong> to the parser. Before parsing, the
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]498application layer registers a customized set of callbacks which are called by
499the library as it progresses through the XML input.</p>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]500
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]501<p>To get more detailed step-by-step guidance on using the SAX interface of
502libxml, see the
503href="http://www.daa.com.au/~james/gnome/xml-sax/xml-sax.html">nice
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]504documentation.written by <a href="mailto:james@daa.com.au">James
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]505Henstridge</a>.</p>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]506
507<p>You can debug the SAX behaviour by using the <strong>testSAX</strong>
508program located in the gnome-xml module (it's usually not shipped in the
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]509binary packages of libxml, but you can find it in the tar source
Daniel Veillard402e8c82000-02-29 22:57:47 +0000[diff] [blame]510distribution). Here is the sequence of callbacks that would be reported by
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]511testSAX when parsing the example XML document shown earlier:</p>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]512<pre>SAX.setDocumentLocator()
513SAX.startDocument()
514SAX.getEntity(amp)
515SAX.startElement(EXAMPLE, prop1='gnome is great', prop2='&amp;amp; linux too')
516SAX.characters( , 3)
517SAX.startElement(head)
518SAX.characters( , 4)
519SAX.startElement(title)
520SAX.characters(Welcome to Gnome, 16)
521SAX.endElement(title)
522SAX.characters( , 3)
523SAX.endElement(head)
524SAX.characters( , 3)
525SAX.startElement(chapter)
526SAX.characters( , 4)
527SAX.startElement(title)
528SAX.characters(The Linux adventure, 19)
529SAX.endElement(title)
530SAX.characters( , 4)
531SAX.startElement(p)
532SAX.characters(bla bla bla ..., 15)
533SAX.endElement(p)
534SAX.characters( , 4)
535SAX.startElement(image, href='linus.gif')
536SAX.endElement(image)
537SAX.characters( , 4)
538SAX.startElement(p)
539SAX.characters(..., 3)
540SAX.endElement(p)
541SAX.characters( , 3)
542SAX.endElement(chapter)
543SAX.characters( , 1)
544SAX.endElement(EXAMPLE)
545SAX.endDocument()</pre>
546
Daniel Veillard402e8c82000-02-29 22:57:47 +0000[diff] [blame]547<p>Most of the other functionalities of libxml are based on the DOM
548tree-building facility, so nearly everything up to the end of this document
549presupposes the use of the standard DOM tree build. Note that the DOM tree
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]550itself is built by a set of registered default callbacks, without internal
551specific interface.</p>
552
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]553<h2><a name="library">The XML library interfaces</a></h2>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]554
555<p>This section is directly intended to help programmers getting bootstrapped
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]556using the XML library from the C language. It is not intended to be extensive.
557I hope the automatically generated documents will provide the completeness
558required, but as a separate set of documents. The interfaces of the XML
559library are by principle low level, there is nearly zero abstraction. Those
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]560interested in a higher level API should <a href="#DOM">look at DOM</a>.</p>
Daniel Veillardccb09631998-10-27 06:21:04 +0000[diff] [blame]561
Daniel Veillardc19fccc2000-07-03 11:52:01 +0000[diff] [blame]562<p>The <a href="html/gnome-xml-parser.html">parser interfaces for XML</a> are
563separated from the <a href="html/gnome-xml-htmlparser.html">HTML parser
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]564interfaces</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]565
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]566<h3><a name="Invoking">Invoking the parser : the pull method</a></h3>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]567
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]568<p>Usually, the first thing to do is to read an XML input. The parser accepts
569documents either from in-memory strings or from files. The functions are
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]570defined in "parser.h":</p>
Daniel Veillard10c6a8f1998-10-28 01:00:12 +0000[diff] [blame]571<dl>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]572 <dt><code>xmlDocPtr xmlParseMemory(char *buffer, int size);</code></dt>
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]573 <dd><p>Parse a null-terminated string containing the document.</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]574 </dd>
Daniel Veillard10c6a8f1998-10-28 01:00:12 +0000[diff] [blame]575</dl>
576<dl>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]577 <dt><code>xmlDocPtr xmlParseFile(const char *filename);</code></dt>
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]578 <dd><p>Parse an XML document contained in a (possibly compressed)
579 file.</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]580 </dd>
Daniel Veillard10c6a8f1998-10-28 01:00:12 +0000[diff] [blame]581</dl>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]582
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]583<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]584failure).</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]585
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]586<h3 id="Invoking1">Invoking the parser: the push method</h3>
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]587
588<p>In order for the application to keep the control when the document is been
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]589fetched (which is common for GUI based programs) libxml provides a push
590interface, too, as of version 1.8.3. Here are the interface functions:</p>
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]591<pre>xmlParserCtxtPtr xmlCreatePushParserCtxt(xmlSAXHandlerPtr sax,
592 void *user_data,
593 const char *chunk,
594 int size,
595 const char *filename);
596int xmlParseChunk (xmlParserCtxtPtr ctxt,
597 const char *chunk,
598 int size,
599 int terminate);</pre>
600
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]601<p>and here is a simple example showing how to use the interface:</p>
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]602<pre> FILE *f;
603
604 f = fopen(filename, "r");
605 if (f != NULL) {
606 int res, size = 1024;
607 char chars[1024];
608 xmlParserCtxtPtr ctxt;
609
610 res = fread(chars, 1, 4, f);
611 if (res > 0) {
612 ctxt = xmlCreatePushParserCtxt(NULL, NULL,
613 chars, res, filename);
614 while ((res = fread(chars, 1, size, f)) > 0) {
615 xmlParseChunk(ctxt, chars, res, 0);
616 }
617 xmlParseChunk(ctxt, chars, 0, 1);
618 doc = ctxt->myDoc;
619 xmlFreeParserCtxt(ctxt);
620 }
621 }</pre>
622
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]623<p>Also note that the HTML parser embedded into libxml also has a push
624interface; the functions are just prefixed by "html" rather than "xml"</p>
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]625
626<h3 id="Invoking2">Invoking the parser: the SAX interface</h3>
627
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]628<p>A couple of comments can be made, first this mean that the parser is
Daniel Veillard10c6a8f1998-10-28 01:00:12 +0000[diff] [blame]629memory-hungry, first to load the document in memory, second to build the tree.
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]630Reading a document without building the tree is possible using the SAX
631interfaces (see SAX.h and <a
632href="http://www.daa.com.au/~james/gnome/xml-sax/xml-sax.html">James
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]633Henstridge's documentation</a>). Note also that the push interface can be
634limited to SAX. Just use the two first arguments of
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]635<code>xmlCreatePushParserCtxt()</code>.</p>
Daniel Veillardccb09631998-10-27 06:21:04 +0000[diff] [blame]636
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]637<h3><a name="Building">Building a tree from scratch</a></h3>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]638
639<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]640there is a set of functions dedicated to building new elements. (These are
Daniel Veillard361d8452000-04-03 19:48:13 +0000[diff] [blame]641also described in &lt;libxml/tree.h>.) For example, here is a piece of code
642that produces the XML document used in the previous examples:</p>
643<pre> #include &lt;libxml/tree.h>
644 xmlDocPtr doc;
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]645 xmlNodePtr tree, subtree;
646
647 doc = xmlNewDoc("1.0");
Daniel Veillard306be992000-07-03 12:38:45 +0000[diff] [blame^]648 doc->children = xmlNewDocNode(doc, NULL, "EXAMPLE", NULL);
649 xmlSetProp(doc->children, "prop1", "gnome is great");
650 xmlSetProp(doc->children, "prop2", "&amp; linux too");
651 tree = xmlNewChild(doc->children, NULL, "head", NULL);
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]652 subtree = xmlNewChild(tree, NULL, "title", "Welcome to Gnome");
Daniel Veillard306be992000-07-03 12:38:45 +0000[diff] [blame^]653 tree = xmlNewChild(doc->children, NULL, "chapter", NULL);
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]654 subtree = xmlNewChild(tree, NULL, "title", "The Linux adventure");
655 subtree = xmlNewChild(tree, NULL, "p", "bla bla bla ...");
656 subtree = xmlNewChild(tree, NULL, "image", NULL);
657 xmlSetProp(subtree, "href", "linus.gif");</pre>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]658
659<p>Not really rocket science ...</p>
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]660
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]661<h3><a name="Traversing">Traversing the tree</a></h3>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]662
Daniel Veillard306be992000-07-03 12:38:45 +0000[diff] [blame^]663<p>Basically by <a href="html/gnome-xml-tree.html">including "tree.h"</a> your
664code has access to the internal structure of all the elements of the tree. The
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]665names should be somewhat simple like <strong>parent</strong>,
Daniel Veillard306be992000-07-03 12:38:45 +0000[diff] [blame^]666<strong>children</strong>, <strong>next</strong>, <strong>prev</strong>,
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]667<strong>properties</strong>, etc... For example, still with the previous
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]668example:</p>
Daniel Veillard306be992000-07-03 12:38:45 +0000[diff] [blame^]669<pre><code>doc->children->children->children</code></pre>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]670
671<p>points to the title element,</p>
Daniel Veillard306be992000-07-03 12:38:45 +0000[diff] [blame^]672<pre>doc->children->children->next->child->child</pre>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]673
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]674<p>points to the text node containing the chapter title "The Linux
675adventure".</p>
Daniel Veillard10c6a8f1998-10-28 01:00:12 +0000[diff] [blame]676
Daniel Veillardb24054a1999-12-18 15:32:46 +0000[diff] [blame]677<p><strong>NOTE</strong>: XML allows <em>PI</em>s and <em>comments</em> to be
Daniel Veillard306be992000-07-03 12:38:45 +0000[diff] [blame^]678present before the document root, so <code>doc->children</code> may point to
679an element which is not the document Root Element, a function
Daniel Veillard5cb5ab81999-12-21 15:35:29 +0000[diff] [blame]680<code>xmlDocGetRootElement()</code> was added for this purpose.</p>
Daniel Veillardb24054a1999-12-18 15:32:46 +0000[diff] [blame]681
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]682<h3><a name="Modifying">Modifying the tree</a></h3>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]683
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]684<p>Functions are provided for reading and writing the document content. Here
Daniel Veillardc19fccc2000-07-03 11:52:01 +0000[diff] [blame]685is an excerpt from the <a href="html/gnome-xml-tree.html">tree API</a>:</p>
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]686<dl>
Daniel Veillarddd6b3671999-09-23 22:19:22 +0000[diff] [blame]687 <dt><code>xmlAttrPtr xmlSetProp(xmlNodePtr node, const xmlChar *name, const
688 xmlChar *value);</code></dt>
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]689 <dd><p>This sets (or changes) an attribute carried by an ELEMENT node. The
690 value can be NULL.</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]691 </dd>
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]692</dl>
693<dl>
Daniel Veillarddd6b3671999-09-23 22:19:22 +0000[diff] [blame]694 <dt><code>const xmlChar *xmlGetProp(xmlNodePtr node, const xmlChar
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]695 *name);</code></dt>
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]696 <dd><p>This function returns a pointer to the property content. Note that
697 no extra copy is made.</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]698 </dd>
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]699</dl>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]700
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]701<p>Two functions are provided for reading and writing the text associated with
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]702elements:</p>
703<dl>
Daniel Veillarddd6b3671999-09-23 22:19:22 +0000[diff] [blame]704 <dt><code>xmlNodePtr xmlStringGetNodeList(xmlDocPtr doc, const xmlChar
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]705 *value);</code></dt>
706 <dd><p>This function takes an "external" string and convert it to one text
707 node or possibly to a list of entity and text nodes. All non-predefined
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]708 entity references like &amp;Gnome; will be stored internally as entity
709 nodes, hence the result of the function may not be a single node.</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]710 </dd>
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]711</dl>
712<dl>
Daniel Veillarddd6b3671999-09-23 22:19:22 +0000[diff] [blame]713 <dt><code>xmlChar *xmlNodeListGetString(xmlDocPtr doc, xmlNodePtr list, int
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]714 inLine);</code></dt>
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]715 <dd><p>This function is the inverse of
716 <code>xmlStringGetNodeList()</code>. It generates a new string
717 containing the content of the text and entity nodes. Note the extra
718 argument inLine. If this argument is set to 1, the function will expand
719 entity references. For example, instead of returning the &amp;Gnome;
720 XML encoding in the string, it will substitute it with its value (say,
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]721 "GNU Network Object Model Environment"). Set this argument if you want
722 to use the string for non-XML usage like User Interface.</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]723 </dd>
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]724</dl>
Daniel Veillard10c6a8f1998-10-28 01:00:12 +0000[diff] [blame]725
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]726<h3><a name="Saving">Saving a tree</a></h3>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]727
728<p>Basically 3 options are possible:</p>
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]729<dl>
Daniel Veillarddd6b3671999-09-23 22:19:22 +0000[diff] [blame]730 <dt><code>void xmlDocDumpMemory(xmlDocPtr cur, xmlChar**mem, int
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]731 *size);</code></dt>
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]732 <dd><p>Returns a buffer into which the document has been saved.</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]733 </dd>
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]734</dl>
735<dl>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]736 <dt><code>extern void xmlDocDump(FILE *f, xmlDocPtr doc);</code></dt>
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]737 <dd><p>Dumps a document to an open file descriptor.</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]738 </dd>
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]739</dl>
740<dl>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]741 <dt><code>int xmlSaveFile(const char *filename, xmlDocPtr cur);</code></dt>
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]742 <dd><p>Saves the document to a file. In this case, the compression
743 interface is triggered if it has been turned on.</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]744 </dd>
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]745</dl>
Daniel Veillard10c6a8f1998-10-28 01:00:12 +0000[diff] [blame]746
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]747<h3><a name="Compressio">Compression</a></h3>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]748
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]749<p>The library transparently handles compression when doing file-based
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]750accesses. The level of compression on saves can be turned on either globally
751or individually for one file:</p>
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]752<dl>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]753 <dt><code>int xmlGetDocCompressMode (xmlDocPtr doc);</code></dt>
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]754 <dd><p>Gets the document compression ratio (0-9).</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]755 </dd>
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]756</dl>
757<dl>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]758 <dt><code>void xmlSetDocCompressMode (xmlDocPtr doc, int mode);</code></dt>
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]759 <dd><p>Sets the document compression ratio.</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]760 </dd>
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]761</dl>
762<dl>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]763 <dt><code>int xmlGetCompressMode(void);</code></dt>
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]764 <dd><p>Gets the default compression ratio.</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]765 </dd>
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]766</dl>
767<dl>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]768 <dt><code>void xmlSetCompressMode(int mode);</code></dt>
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]769 <dd><p>Sets the default compression ratio.</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]770 </dd>
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]771</dl>
772
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]773<h2><a name="Entities">Entities or no entities</a></h2>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]774
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]775<p>Entities in principle are similar to simple C macros. An entity defines an
776abbreviation for a given string that you can reuse many times throughout the
777content of your document. Entities are especially useful when a given string
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]778may occur frequently within a document, or to confine the change needed to a
779document to a restricted area in the internal subset of the document (at the
780beginning). Example:</p>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]781<pre>1 &lt;?xml version="1.0"?>
7822 &lt;!DOCTYPE EXAMPLE SYSTEM "example.dtd" [
7833 &lt;!ENTITY xml "Extensible Markup Language">
7844 ]>
7855 &lt;EXAMPLE>
7866 &amp;xml;
Daniel Veillard35008381999-10-25 13:15:52 +0000[diff] [blame]7877 &lt;/EXAMPLE></pre>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]788
789<p>Line 3 declares the xml entity. Line 6 uses the xml entity, by prefixing
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]790it's name with '&amp;' and following it by ';' without any spaces added. There
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]791are 5 predefined entities in libxml allowing you to escape charaters with
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]792predefined meaning in some parts of the xml document content:
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]793<strong>&amp;lt;</strong> for the character '&lt;', <strong>&amp;gt;</strong>
794for the character '>', <strong>&amp;apos;</strong> for the character ''',
795<strong>&amp;quot;</strong> for the character '"', and
796<strong>&amp;amp;</strong> for the character '&amp;'.</p>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]797
798<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]799substitute an entity's content so that you can see the replacement text in
800your application. Or you may prefer to keep entity references as such in the
801content to be able to save the document back without losing this usually
802precious information (if the user went through the pain of explicitly defining
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]803entities, he may have a a rather negative attitude if you blindly susbtitute
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]804them as saving time). The <a
Daniel Veillardc19fccc2000-07-03 11:52:01 +0000[diff] [blame]805href="html/gnome-xml-parser.html#XMLSUBSTITUTEENTITIESDEFAULT">xmlSubstituteEntitiesDefault()</a>
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]806function allows you to check and change the behaviour, which is to not
807substitute entities by default.</p>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]808
809<p>Here is the DOM tree built by libxml for the previous document in the
810default case:</p>
Daniel Veillard361d8452000-04-03 19:48:13 +0000[diff] [blame]811<pre>/gnome/src/gnome-xml -> ./xmllint --debug test/ent1
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]812DOCUMENT
813version=1.0
814 ELEMENT EXAMPLE
815 TEXT
816 content=
817 ENTITY_REF
818 INTERNAL_GENERAL_ENTITY xml
819 content=Extensible Markup Language
820 TEXT
821 content=</pre>
822
823<p>And here is the result when substituting entities:</p>
824<pre>/gnome/src/gnome-xml -> ./tester --debug --noent test/ent1
825DOCUMENT
826version=1.0
827 ELEMENT EXAMPLE
828 TEXT
829 content= Extensible Markup Language</pre>
830
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]831<p>So, entities or no entities? Basically, it depends on your use case. I
832suggest that you keep the non-substituting default behaviour and avoid using
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]833entities in your XML document or data if you are not willing to handle the
834entity references elements in the DOM tree.</p>
835
836<p>Note that at save time libxml enforce the conversion of the predefined
837entities where necessary to prevent well-formedness problems, and will also
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]838transparently replace those with chars (i.e., it will not generate entity
839reference elements in the DOM tree or call the reference() SAX callback when
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]840finding them in the input).</p>
841
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]842<h2><a name="Namespaces">Namespaces</a></h2>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]843
Daniel Veillardec303412000-03-24 13:41:54 +0000[diff] [blame]844<p>The libxml library implements <a
845href="http://www.w3.org/TR/REC-xml-names/">XML namespaces</a> support by
846recognizing namespace contructs in the input, and does namespace lookup
847automatically when building the DOM tree. A namespace declaration is
848associated with an in-memory structure and all elements or attributes within
849that namespace point to it. Hence testing the namespace is a simple and fast
850equality operation at the user level.</p>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]851
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]852<p>I suggest that people using libxml use a namespace, and declare it in the
853root element of their document as the default namespace. Then they don't need
854to use the prefix in the content but we will have a basis for future semantic
855refinement and merging of data from different sources. This doesn't augment
856significantly the size of the XML output, but significantly increase its value
Daniel Veillardec303412000-03-24 13:41:54 +0000[diff] [blame]857in the long-term. Example:</p>
858<pre>&lt;mydoc xmlns="http://mydoc.example.org/schemas/">
859 &lt;elem1>...&lt;/elem1>
860 &lt;elem2>...&lt;/elem2>
861&lt;/mydoc></pre>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]862
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]863<p>Concerning the namespace value, this has to be an URL, but the URL doesn't
Daniel Veillardec303412000-03-24 13:41:54 +0000[diff] [blame]864have to point to any existing resource on the Web. It will bind all the
865element and atributes with that URL. I suggest to use an URL within a domain
866you control, and that the URL should contain some kind of version information
867if possible. For example, <code>"http://www.gnome.org/gnumeric/1.0/"</code> is
Daniel Veillard361d8452000-04-03 19:48:13 +0000[diff] [blame]868a good namespace scheme.</p>
Daniel Veillardec303412000-03-24 13:41:54 +0000[diff] [blame]869
870<p>Then when you load a file, make sure that a namespace carrying the
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]871version-independent prefix is installed on the root element of your document,
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]872and if the version information don't match something you know, warn the user
873and be liberal in what you accept as the input. Also do *not* try to base
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]874namespace checking on the prefix value. &lt;foo:text> may be exactly the same
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]875as &lt;bar:text> in another document. What really matter is the URI associated
876with the element or the attribute, not the prefix string (which is just a
Daniel Veillardec303412000-03-24 13:41:54 +0000[diff] [blame]877shortcut for the full URI). In libxml element and attributes have a
878<code>ns</code> field pointing to an xmlNs structure detailing the namespace
879prefix and it's URI.</p>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]880
881<p>@@Interfaces@@</p>
882
883<p>@@Examples@@</p>
884
885<p>Usually people object using namespace in the case of validation, I object
886this and will make sure that using namespaces won't break validity checking,
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]887so even is you plan to use or currently are using validation I strongly
888suggest adding namespaces to your document. A default namespace scheme
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]889<code>xmlns="http://...."</code> should not break validity even on less
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]890flexible parsers. Now using namespace to mix and differentiate content coming
891from multiple DTDs will certainly break current validation schemes. I will try
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]892to provide ways to do this, but this may not be portable or standardized.</p>
893
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]894<h2><a name="Validation">Validation, or are you afraid of DTDs ?</a></h2>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]895
896<p>Well what is validation and what is a DTD ?</p>
897
898<p>Validation is the process of checking a document against a set of
899construction rules, a <strong>DTD</strong> (Document Type Definition) is such
900a set of rules.</p>
901
902<p>The validation process and building DTDs are the two most difficult parts
903of XML life cycle. Briefly a DTD defines all the possibles element to be
904found within your document, what is the formal shape of your document tree (by
905defining the allowed content of an element, either text, a regular expression
Daniel Veillard306be992000-07-03 12:38:45 +0000[diff] [blame^]906for the allowed list of children, or mixed content i.e. both text and
907children). The DTD also defines the allowed attributes for all elements and
908the types of the attributes. For more detailed informations, I suggest to read
909the related parts of the XML specification, the examples found under
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]910gnome-xml/test/valid/dtd and the large amount of books available on XML. The
911dia example in gnome-xml/test/valid should be both simple and complete enough
912to allow you to build your own.</p>
913
914<p>A word of warning, building a good DTD which will fit your needs of your
915application in the long-term is far from trivial, however the extra level of
916quality it can insure is well worth the price for some sets of applications or
917if you already have already a DTD defined for your application field.</p>
918
919<p>The validation is not completely finished but in a (very IMHO) usable
920state. Until a real validation interface is defined the way to do it is to
921define and set the <strong>xmlDoValidityCheckingDefaultValue</strong> external
922variable to 1, this will of course be changed at some point:</p>
923
924<p>extern int xmlDoValidityCheckingDefaultValue;</p>
925
926<p>...</p>
927
928<p>xmlDoValidityCheckingDefaultValue = 1;</p>
929
930<p></p>
931
932<p>To handle external entities, use the function
933<strong>xmlSetExternalEntityLoader</strong>(xmlExternalEntityLoader f); to
934link in you HTTP/FTP/Entities database library to the standard libxml
935core.</p>
936
937<p>@@interfaces@@</p>
938
Daniel Veillard35008381999-10-25 13:15:52 +0000[diff] [blame]939<h2><a name="DOM"></a><a name="Principles">DOM Principles</a></h2>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]940
941<p><a href="http://www.w3.org/DOM/">DOM</a> stands for the <em>Document Object
Daniel Veillardccb09631998-10-27 06:21:04 +0000[diff] [blame]942Model</em> this is an API for accessing XML or HTML structured documents.
943Native support for DOM in Gnome is on the way (module gnome-dom), and it will
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]944be based on gnome-xml. This will be a far cleaner interface to manipulate XML
Daniel Veillardc08a2c61999-09-08 21:35:25 +0000[diff] [blame]945files within Gnome since it won't expose the internal structure. DOM defines a
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]946set of IDL (or Java) interfaces allowing to traverse and manipulate a
947document. The DOM library will allow accessing and modifying "live" documents
948presents on other programs like this:</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]949
950<p><img src="DOM.gif" alt=" DOM.gif "></p>
951
952<p>This should help greatly doing things like modifying a gnumeric spreadsheet
Daniel Veillardccb09631998-10-27 06:21:04 +0000[diff] [blame]953embedded in a GWP document for example.</p>
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]954
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]955<p>The current DOM implementation on top of libxml is the <a
956href="http://cvs.gnome.org/lxr/source/gdome/">gdome Gnome module</a>, this is
957a full DOM interface, thanks to <a href="mailto:raph@levien.com">Raph
958Levien</a>.</p>
959
960<p>The gnome-dom module in the Gnome CVS base is obsolete</p>
961
Daniel Veillard35008381999-10-25 13:15:52 +0000[diff] [blame]962<h2><a name="Example"></a><a name="real">A real example</a></h2>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]963
964<p>Here is a real size example, where the actual content of the application
965data 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]966a proposal to keep a database of jobs related to Gnome, with an XML based
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]967storage structure. Here is an <a href="gjobs.xml">XML encoded jobs
968base</a>:</p>
969<pre>&lt;?xml version="1.0"?>
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]970&lt;gjob:Helping xmlns:gjob="http://www.gnome.org/some-location">
971 &lt;gjob:Jobs>
972
973 &lt;gjob:Job>
974 &lt;gjob:Project ID="3"/>
975 &lt;gjob:Application>GBackup&lt;/gjob:Application>
976 &lt;gjob:Category>Development&lt;/gjob:Category>
977
978 &lt;gjob:Update>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]979 &lt;gjob:Status>Open&lt;/gjob:Status>
980 &lt;gjob:Modified>Mon, 07 Jun 1999 20:27:45 -0400 MET DST&lt;/gjob:Modified>
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]981 &lt;gjob:Salary>USD 0.00&lt;/gjob:Salary>
982 &lt;/gjob:Update>
983
984 &lt;gjob:Developers>
985 &lt;gjob:Developer>
986 &lt;/gjob:Developer>
987 &lt;/gjob:Developers>
988
989 &lt;gjob:Contact>
990 &lt;gjob:Person>Nathan Clemons&lt;/gjob:Person>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]991 &lt;gjob:Email>nathan@windsofstorm.net&lt;/gjob:Email>
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]992 &lt;gjob:Company>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]993 &lt;/gjob:Company>
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]994 &lt;gjob:Organisation>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]995 &lt;/gjob:Organisation>
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]996 &lt;gjob:Webpage>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]997 &lt;/gjob:Webpage>
998 &lt;gjob:Snailmail>
999 &lt;/gjob:Snailmail>
1000 &lt;gjob:Phone>
1001 &lt;/gjob:Phone>
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]1002 &lt;/gjob:Contact>
1003
1004 &lt;gjob:Requirements>
1005 The program should be released as free software, under the GPL.
1006 &lt;/gjob:Requirements>
1007
1008 &lt;gjob:Skills>
1009 &lt;/gjob:Skills>
1010
1011 &lt;gjob:Details>
1012 A GNOME based system that will allow a superuser to configure
1013 compressed and uncompressed files and/or file systems to be backed
1014 up with a supported media in the system. This should be able to
1015 perform via find commands generating a list of files that are passed
1016 to tar, dd, cpio, cp, gzip, etc., to be directed to the tape machine
1017 or via operations performed on the filesystem itself. Email
1018 notification and GUI status display very important.
1019 &lt;/gjob:Details>
1020
1021 &lt;/gjob:Job>
1022
1023 &lt;/gjob:Jobs>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]1024&lt;/gjob:Helping></pre>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]1025
1026<p>While loading the XML file into an internal DOM tree is a matter of calling
1027only a couple of functions, browsing the tree to gather the informations and
1028generate the internals structures is harder, and more error prone.</p>
1029
1030<p>The suggested principle is to be tolerant with respect to the input
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]1031structure. For example, the ordering of the attributes is not significant,
1032Cthe XML specification is clear about it. It's also usually a good idea to not
Daniel Veillard306be992000-07-03 12:38:45 +0000[diff] [blame^]1033be dependent of the orders of the children of a given node, unless it really
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]1034makes things harder. Here is some code to parse the informations for a
1035person:</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]1036<pre>/*
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]1037 * A person record
1038 */
1039typedef struct person {
1040 char *name;
1041 char *email;
1042 char *company;
1043 char *organisation;
1044 char *smail;
1045 char *webPage;
1046 char *phone;
1047} person, *personPtr;
1048
1049/*
1050 * And the code needed to parse it
1051 */
1052personPtr parsePerson(xmlDocPtr doc, xmlNsPtr ns, xmlNodePtr cur) {
1053 personPtr ret = NULL;
1054
1055DEBUG("parsePerson\n");
1056 /*
1057 * allocate the struct
1058 */
1059 ret = (personPtr) malloc(sizeof(person));
1060 if (ret == NULL) {
1061 fprintf(stderr,"out of memory\n");
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]1062 return(NULL);
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]1063 }
1064 memset(ret, 0, sizeof(person));
1065
1066 /* We don't care what the top level element name is */
Daniel Veillard306be992000-07-03 12:38:45 +0000[diff] [blame^]1067 cur = cur->xmlChildrenNode;
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]1068 while (cur != NULL) {
1069 if ((!strcmp(cur->name, "Person")) &amp;&amp; (cur->ns == ns))
Daniel Veillard306be992000-07-03 12:38:45 +0000[diff] [blame^]1070 ret->name = xmlNodeListGetString(doc, cur->xmlChildrenNode, 1);
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]1071 if ((!strcmp(cur->name, "Email")) &amp;&amp; (cur->ns == ns))
Daniel Veillard306be992000-07-03 12:38:45 +0000[diff] [blame^]1072 ret->email = xmlNodeListGetString(doc, cur->xmlChildrenNode, 1);
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]1073 cur = cur->next;
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]1074 }
1075
1076 return(ret);
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]1077}</pre>
1078
1079<p>Here is a couple of things to notice:</p>
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]1080<ul>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]1081 <li>Usually a recursive parsing style is the more convenient one, XML data
1082 being by nature subject to repetitive constructs and usualy exibit highly
1083 stuctured patterns.</li>
1084 <li>The two arguments of type <em>xmlDocPtr</em> and <em>xmlNsPtr</em>, i.e.
1085 the pointer to the global XML document and the namespace reserved to the
1086 application. Document wide information are needed for example to decode
1087 entities and it's a good coding practice to define a namespace for your
1088 application set of data and test that the element and attributes you're
1089 analyzing actually pertains to your application space. This is done by a
1090 simple equality test (cur->ns == ns).</li>
1091 <li>To retrieve text and attributes value, it is suggested to use the
1092 function <em>xmlNodeListGetString</em> to gather all the text and entity
1093 reference nodes generated by the DOM output and produce an single text
1094 string.</li>
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]1095</ul>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]1096
1097<p>Here is another piece of code used to parse another level of the
1098structure:</p>
Daniel Veillard361d8452000-04-03 19:48:13 +0000[diff] [blame]1099<pre>#include &lt;libxml/tree.h>
1100/*
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]1101 * a Description for a Job
1102 */
1103typedef struct job {
1104 char *projectID;
1105 char *application;
1106 char *category;
1107 personPtr contact;
1108 int nbDevelopers;
1109 personPtr developers[100]; /* using dynamic alloc is left as an exercise */
1110} job, *jobPtr;
1111
1112/*
1113 * And the code needed to parse it
1114 */
1115jobPtr parseJob(xmlDocPtr doc, xmlNsPtr ns, xmlNodePtr cur) {
1116 jobPtr ret = NULL;
1117
1118DEBUG("parseJob\n");
1119 /*
1120 * allocate the struct
1121 */
1122 ret = (jobPtr) malloc(sizeof(job));
1123 if (ret == NULL) {
1124 fprintf(stderr,"out of memory\n");
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]1125 return(NULL);
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]1126 }
1127 memset(ret, 0, sizeof(job));
1128
1129 /* We don't care what the top level element name is */
Daniel Veillard306be992000-07-03 12:38:45 +0000[diff] [blame^]1130 cur = cur->xmlChildrenNode;
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]1131 while (cur != NULL) {
1132
1133 if ((!strcmp(cur->name, "Project")) &amp;&amp; (cur->ns == ns)) {
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]1134 ret->projectID = xmlGetProp(cur, "ID");
1135 if (ret->projectID == NULL) {
1136 fprintf(stderr, "Project has no ID\n");
1137 }
1138 }
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]1139 if ((!strcmp(cur->name, "Application")) &amp;&amp; (cur->ns == ns))
Daniel Veillard306be992000-07-03 12:38:45 +0000[diff] [blame^]1140 ret->application = xmlNodeListGetString(doc, cur->xmlChildrenNode, 1);
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]1141 if ((!strcmp(cur->name, "Category")) &amp;&amp; (cur->ns == ns))
Daniel Veillard306be992000-07-03 12:38:45 +0000[diff] [blame^]1142 ret->category = xmlNodeListGetString(doc, cur->xmlChildrenNode, 1);
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]1143 if ((!strcmp(cur->name, "Contact")) &amp;&amp; (cur->ns == ns))
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]1144 ret->contact = parsePerson(doc, ns, cur);
1145 cur = cur->next;
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]1146 }
1147
1148 return(ret);
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]1149}</pre>
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]1150
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]1151<p>One can notice that once used to it, writing this kind of code is quite
1152simple, but boring. Ultimately, it could be possble to write stubbers taking
1153either C data structure definitions, a set of XML examples or an XML DTD and
1154produce the code needed to import and export the content between C data and
1155XML storage. This is left as an exercise to the reader :-)</p>
1156
Daniel Veillard6f0adb52000-07-03 11:41:26 +0000[diff] [blame]1157<p>Feel free to use <a href="example/gjobread.c">the code for the full C
1158parsing example</a> as a template, it is also available with Makefile in the
1159Gnome CVS base under gnome-xml/example</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]1160
Daniel Veillardc310d562000-06-23 18:32:15 +0000[diff] [blame]1161<h2><a name="Contributi">Contributions</a></h2>
1162<ul>
1163 <li><a href="mailto:ari@btigate.com">Ari Johnson</a> provides a C++ wrapper
1164 for libxml:
1165 <p>Website: <a
1166 href="http://lusis.org/~ari/xml++/">http://lusis.org/~ari/xml++/</a></p>
1167 <p>Download: <a
1168 href="http://lusis.org/~ari/xml++/libxml++.tar.gz">http://lusis.org/~ari/xml++/libxml++.tar.gz</a></p>
1169 </li>
1170 <li><a href="mailto:doolin@cs.utk.edu">David Doolin</a> provides a
1171 precompiled Windows version
1172 <p><a
1173 href="http://www.ce.berkeley.edu/~doolin/code/libxmlwin32/">http://www.ce.berkeley.edu/~doolin/code/libxmlwin32/</a></p>
1174 </li>
Daniel Veillard3f6f7f62000-06-30 17:58:25 +0000[diff] [blame]1175 <li><a href="mailto:fnatter@gmx.net">Felix Natter</a> provided <a
1176 href="libxml-doc.el">an emacs module</a> to lookup libxml functions
1177 documentation</li>
Daniel Veillardc310d562000-06-23 18:32:15 +0000[diff] [blame]1178 <li><a href="mailto:sherwin@nlm.nih.gov">Ziying Sherwin</a> provided <a
1179 href="http://xmlsoft.org/messages/0488.html">man pages</a> (not yet
1180 integrated in the distribution)</li>
1181</ul>
1182
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]1183<p></p>
1184
1185<p><a href="mailto:Daniel.Veillard@w3.org">Daniel Veillard</a></p>
1186
Daniel Veillard306be992000-07-03 12:38:45 +0000[diff] [blame^]1187<p>$Id: xml.html,v 1.38 2000/07/03 11:52:01 veillard Exp $</p>
Daniel Veillardccb09631998-10-27 06:21:04 +0000[diff] [blame]1188</body>
1189</html>