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Daniel Veillard3f3b4f32001-03-13 15:12:39 +0000[diff] [blame]5 <title>Libxml Frequently Asked Questions</title>
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Daniel Veillard3f3b4f32001-03-13 15:12:39 +0000[diff] [blame]11<h1 align="center">Libxml Frequently Asked Questions</h1>
Daniel Veillardaf743792000-07-01 11:49:28 +0000[diff] [blame]12
13<p>Location: <a
14href="http://xmlsoft.org/FAQ.html">http://xmlsoft.org/FAQ.html</a></p>
15
16<p>Libxml home page: <a href="http://xmlsoft.org/">http://xmlsoft.org/</a></p>
17
18<p>Mailing-list archive: <a
19href="http://xmlsoft.org/messages/">http://xmlsoft.org/messages/</a></p>
20
Daniel Veillardbe40c8b2000-07-14 12:10:59 +0000[diff] [blame]21<p>Version: $Revision$</p>
Daniel Veillardaf743792000-07-01 11:49:28 +0000[diff] [blame]22
23<p>Table of Content:</p>
24<ul>
25 <li><a href="#Licence">Licence(s)</a></li>
26 <li><a href="#Installati">Installation</a></li>
27 <li><a href="#Compilatio">Compilation</a></li>
Daniel Veillard3f3b4f32001-03-13 15:12:39 +0000[diff] [blame]28 <li><a href="#Developer">Developer corner</a></li>
Daniel Veillardaf743792000-07-01 11:49:28 +0000[diff] [blame]29</ul>
30
31<h2><a name="Licence">Licence</a>(s)</h2>
32<ol>
33 <li><em>Licensing Terms for libxml</em>
34 <p>libxml is released under 2 (compatible) licences:</p>
35 <ul>
36 <li>the <a href="http://www.gnu.org/copyleft/lgpl.html">LGPL</a>: GNU
37 Library General Public License</li>
38 <li>the <a
39 href="http://www.w3.org/Consortium/Legal/copyright-software-19980720.html">W3C
40 IPR</a>: very similar to the XWindow licence</li>
41 </ul>
42 </li>
43 <li><em>Can I embed libxml in a proprietary application ?</em>
44 <p>Yes. The W3C IPR allows you to also keep proprietary the changes you
45 made to libxml, but it would be graceful to provide back bugfixes and
Daniel Veillard480363b2001-03-16 22:04:15 +0000[diff] [blame]46 improvements as patches for possible incorporation in the main development
47 tree</p>
Daniel Veillardaf743792000-07-01 11:49:28 +0000[diff] [blame]48 </li>
49</ol>
50
51<h2><a name="Installati">Installation</a></h2>
52<ol>
Daniel Veillarde0c1d722001-03-21 10:28:36 +0000[diff] [blame]53 <li>Unless you are forced to because your application links with a Gnome
54 library requiring it, <strong><span style="background-color: #FF0000">Do
55 Not Use libxml1</span></strong>, use libxml2</li>
Daniel Veillardaf743792000-07-01 11:49:28 +0000[diff] [blame]56 <li><em>Where can I get libxml</em> ?
57 <p>The original distribution comes from <a
58 href="ftp://rpmfind.net/pub/libxml/">rpmfind.net</a> or <a
59 href="ftp://ftp.gnome.org/pub/GNOME/stable/sources/libxml/">gnome.org</a></p>
60 <p>Most linux and Bsd distribution includes libxml, this is probably the
61 safer way for end-users</p>
62 <p>David Doolin provides precompiled Windows versions at <a
Daniel Veillarde9202a02000-10-16 16:58:19 +0000[diff] [blame]63 href="http://www.ce.berkeley.edu/~doolin/code/libxmlwin32/ ">http://www.ce.berkeley.edu/~doolin/code/libxmlwin32/</a></p>
Daniel Veillardaf743792000-07-01 11:49:28 +0000[diff] [blame]64 </li>
65 <li><em>I see libxml and libxml2 releases, which one should I install ?</em>
66 <ul>
67 <li>If you are not concerned by any existing backward compatibility with
68 existing application, install libxml2 only</li>
69 <li>If you are not doing development, you can safely install both.
70 usually the packages <a
71 href="http://rpmfind.net/linux/RPM/libxml.html">libxml</a> and <a
72 href="http://rpmfind.net/linux/RPM/libxml2.html">libxml2</a> are
73 compatible (this is not the case for development packages)</li>
Daniel Veillard3f3b4f32001-03-13 15:12:39 +0000[diff] [blame]74 <li>If you are a developer and your system provides separate packaging
Daniel Veillardaf743792000-07-01 11:49:28 +0000[diff] [blame]75 for shared libraries and the development components, it is possible to
Daniel Veillard480363b2001-03-16 22:04:15 +0000[diff] [blame]76 install libxml and libxml2, and also <a
Daniel Veillardaf743792000-07-01 11:49:28 +0000[diff] [blame]77 href="http://rpmfind.net/linux/RPM/libxml-devel.html">libxml-devel</a>
Daniel Veillard480363b2001-03-16 22:04:15 +0000[diff] [blame]78 and <a
Daniel Veillardaf743792000-07-01 11:49:28 +0000[diff] [blame]79 href="http://rpmfind.net/linux/RPM/libxml2-devel.html">libxml2-devel</a>
Daniel Veillard480363b2001-03-16 22:04:15 +0000[diff] [blame]80 too for libxml2 &gt;= 2.3.0</li>
Daniel Veillard3f3b4f32001-03-13 15:12:39 +0000[diff] [blame]81 <li>If you are developing a new application, please develop against
Daniel Veillardaf743792000-07-01 11:49:28 +0000[diff] [blame]82 libxml2(-devel)</li>
83 </ul>
84 </li>
85 <li><em>I can't install the libxml package it conflicts with libxml0</em>
86 <p>You probably have an old libxml0 package used to provide the shared
87 library for libxml.so.0, you can probably safely remove it. Anyway the
88 libxml packages provided on <a
89 href="ftp://rpmfind.net/pub/libxml/">rpmfind.net</a> provides
90 libxml.so.0</p>
91 </li>
Daniel Veillardc654d602001-05-01 12:42:26 +0000[diff] [blame^]92 <li><em>I can't install the libxml(2) RPM package due to failed
93 dependancies</em>
94 <p>The most generic solution is to refetch the latest src.rpm , and
95 rebuild it locally with</p>
96 <p><code>rpm --rebuild libxml(2)-xxx.src.rpm</code></p>
97 <p>if everything goes well it will generate two binary rpm (one providing
98 the shared libs and xmllint, and the other one, the -devel package
99 providing includes, static libraries and scripts needed to build
100 applications with libxml(2)) that you can install locally.</p>
101 </li>
Daniel Veillardaf743792000-07-01 11:49:28 +0000[diff] [blame]102</ol>
103
104<h2><a name="Compilatio">Compilation</a></h2>
105<ol>
106 <li><em>What is the process to compile libxml ?</em>
107 <p>As most UNIX libraries libxml follows the "standard":</p>
108 <p><code>gunzip -c xxx.tar.gz | tar xvf -</code></p>
109 <p><code>cd libxml-xxxx</code></p>
110 <p><code>./configure --help</code></p>
111 <p>to see the options, then the compilation/installation proper</p>
112 <p><code>./configure [possible options]</code></p>
113 <p><code>make</code></p>
114 <p><code>make install</code></p>
115 <p>At that point you may have to rerun ldconfig or similar utility to
116 update your list of installed shared libs.</p>
117 </li>
118 <li><em>What other libraries are needed to compile/install libxml ?</em>
119 <p>Libxml does not requires any other library, the normal C ANSI API
120 should be sufficient (please report any violation to this rule you may
121 find).</p>
Daniel Veillard3f3b4f32001-03-13 15:12:39 +0000[diff] [blame]122 <p>However if found at configuration time libxml will detect and use the
Daniel Veillardaf743792000-07-01 11:49:28 +0000[diff] [blame]123 following libs:</p>
124 <ul>
125 <li><a href="http://www.info-zip.org/pub/infozip/zlib/">libz</a>: a
126 highly portable and available widely compression library</li>
127 <li>iconv: a powerful character encoding conversion library. It's
128 included by default on recent glibc libraries, so it doesn't need to
129 be installed specifically on linux. It seems it's now <a
130 href="http://www.opennc.org/onlinepubs/7908799/xsh/iconv.html">part of
Daniel Veillarde9202a02000-10-16 16:58:19 +0000[diff] [blame]131 the official UNIX</a> specification. Here is one <a
132 href="http://clisp.cons.org/~haible/packages-libiconv.html">implementation
133 of the library</a> which source can be found <a
Daniel Veillard7f41b3e2001-02-10 09:35:37 +0000[diff] [blame]134 href="ftp://ftp.ilog.fr/pub/Users/haible/gnu/">here</a>.</li>
Daniel Veillardaf743792000-07-01 11:49:28 +0000[diff] [blame]135 </ul>
136 </li>
Daniel Veillardaf743792000-07-01 11:49:28 +0000[diff] [blame]137 <li><em>libxml does not compile with HP-UX's optional ANSI-C compiler</em>
138 <p>this is due to macro limitations. Try to add " -Wp,-H16800 -Ae" to the
139 CFLAGS</p>
140 <p>you can also install and use gcc instead or use a precompiled version
141 of libxml, both available from the <a
142 href="http://hpux.cae.wisc.edu/hppd/auto/summary_all.html">HP-UX Porting
143 and Archive Centre</a></p>
144 </li>
145 <li><em>make check fails on some platforms</em>
146 <p>Sometime the regression tests results don't completely match the value
147 produced by the parser, and the makefile uses diff to print the delta. On
148 some platforms the diff return breaks the compilation process, if the diff
149 is small this is probably not a serious problem</p>
150 </li>
151</ol>
152
Daniel Veillard3f3b4f32001-03-13 15:12:39 +0000[diff] [blame]153<h2><a name="Developer">Developer</a> corner</h2>
Daniel Veillardaf743792000-07-01 11:49:28 +0000[diff] [blame]154<ol>
Daniel Veillard7f41b3e2001-02-10 09:35:37 +0000[diff] [blame]155 <li>Extra nodes in the document:
Daniel Veillard62bccd52001-02-10 09:40:10 +0000[diff] [blame]156 <p><em>For a XML file as below:</em></p>
157 <pre>&lt;?xml version="1.0"?&gt;
Daniel Veillarda6663592001-02-10 09:41:12 +0000[diff] [blame]158&lt;PLAN xmlns="http://www.argus.ca/autotest/1.0/"&gt;
Daniel Veillard62bccd52001-02-10 09:40:10 +0000[diff] [blame]159&lt;NODE CommFlag="0"/&gt;
160&lt;NODE CommFlag="1"/&gt;
161&lt;/PLAN&gt;</pre>
Daniel Veillard480363b2001-03-16 22:04:15 +0000[diff] [blame]162 <p><em>after parsing it with the function
163 pxmlDoc=xmlParseFile(...);</em></p>
Daniel Veillard7f41b3e2001-02-10 09:35:37 +0000[diff] [blame]164 <p><em>I want to the get the content of the first node (node with the
165 CommFlag="0")</em></p>
166 <p><em>so I did it as following;</em></p>
Daniel Veillard62bccd52001-02-10 09:40:10 +0000[diff] [blame]167 <pre>xmlNodePtr pode;
168pnode=pxmlDoc-&gt;children-&gt;children;</pre>
Daniel Veillard7f41b3e2001-02-10 09:35:37 +0000[diff] [blame]169 <p><em>but it does not work. If I change it to</em></p>
Daniel Veillard62bccd52001-02-10 09:40:10 +0000[diff] [blame]170 <pre>pnode=pxmlDoc-&gt;children-&gt;children-&gt;next;</pre>
Daniel Veillard7f41b3e2001-02-10 09:35:37 +0000[diff] [blame]171 <p><em>then it works. Can someone explain it to me.</em></p>
172 <p></p>
Daniel Veillard3f3b4f32001-03-13 15:12:39 +0000[diff] [blame]173 <p>In XML all characters in the content of the document are significant
Daniel Veillard7f41b3e2001-02-10 09:35:37 +0000[diff] [blame]174 <strong>including blanks and formatting line breaks</strong>.</p>
175 <p>The extra nodes you are wondering about are just that, text nodes with
176 the formatting spaces wich are part of the document but that people tend
177 to forget. There is a function <a
178 href="http://xmlsoft.org/html/libxml-parser.html">xmlKeepBlanksDefault
179 ()</a> to remove those at parse time, but that's an heuristic, and its
180 use should be limited to case where you are sure there is no mixed-content
181 in the document.</p>
182 </li>
Daniel Veillardaf743792000-07-01 11:49:28 +0000[diff] [blame]183 <li><em>I get compilation errors of existing code like when accessing
184 <strong>root</strong> or <strong>childs fields</strong> of nodes</em>
Daniel Veillard3f3b4f32001-03-13 15:12:39 +0000[diff] [blame]185 <p>You are compiling code developed for libxml version 1 and using a
186 libxml2 development environment. Either switch back to libxml v1 devel or
Daniel Veillardaf743792000-07-01 11:49:28 +0000[diff] [blame]187 even better fix the code to compile with libxml2 (or both) by <a
188 href="upgrade.html">following the instructions</a>.</p>
189 </li>
190 <li><em>I get compilation errors about non existing
191 <strong>xmlRootNode</strong> or <strong>xmlChildrenNode</strong>
192 fields</em>
193 <p>The source code you are using has been <a
194 href="upgrade.html">upgraded</a> to be able to compile with both libxml
195 and libxml2, but you need to install a more recent version: libxml(-devel)
Daniel Veillarde9202a02000-10-16 16:58:19 +0000[diff] [blame]196 &gt;= 1.8.8 or libxml2(-devel) &gt;= 2.1.0</p>
Daniel Veillardaf743792000-07-01 11:49:28 +0000[diff] [blame]197 </li>
198 <li><em>XPath implementation looks seriously broken</em>
Daniel Veillard7f41b3e2001-02-10 09:35:37 +0000[diff] [blame]199 <p>XPath implementation prior to 2.3.0 was really incomplete, upgrade to a
200 recent version, the implementation and debug of libxslt generated fixes
Daniel Veillard480363b2001-03-16 22:04:15 +0000[diff] [blame]201 for most obvious problems.</p>
Daniel Veillardaf743792000-07-01 11:49:28 +0000[diff] [blame]202 </li>
203 <li><em>The example provided in the web page does not compile</em>
204 <p>It's hard to maintain the documentation in sync with the code
Daniel Veillarde9202a02000-10-16 16:58:19 +0000[diff] [blame]205 &lt;grin/&gt; ...</p>
Daniel Veillardaf743792000-07-01 11:49:28 +0000[diff] [blame]206 <p>Check the previous points 1/ and 2/ raised before, and send
207 patches.</p>
208 </li>
209 <li><em>Where can I get more examples and informations than in the web
210 page</em>
211 <p>Ideally a libxml book would be nice. I have no such plan ... But you
212 can:</p>
213 <ul>
Daniel Veillarde9202a02000-10-16 16:58:19 +0000[diff] [blame]214 <li>check more deeply the <a href="html/libxml-lib.html">existing
215 generated doc</a></li>
Daniel Veillardaf743792000-07-01 11:49:28 +0000[diff] [blame]216 <li>looks for examples of use for libxml function using the Gnome code
217 for example the following will query the full Gnome CVs base for the
218 use of the <strong>xmlAddChild()</strong> function:
219 <p><a
220 href="http://cvs.gnome.org/lxr/search?string=xmlAddChild">http://cvs.gnome.org/lxr/search?string=xmlAddChild</a></p>
221 <p>This may be slow, a large hardware donation to the gnome project
222 could cure this :-)</p>
223 </li>
224 <li><a
Daniel Veillarde9202a02000-10-16 16:58:19 +0000[diff] [blame]225 href="http://cvs.gnome.org/bonsai/rview.cgi?cvsroot=/cvs/gnome&amp;dir=gnome-xml">Browse
Daniel Veillardaf743792000-07-01 11:49:28 +0000[diff] [blame]226 the libxml source</a>, I try to write code as clean and documented as
227 possible, so looking at it may be helpful</li>
228 </ul>
229 </li>
230 <li>What about C++ ?
231 <p>libxml is written in pure C in order to allow easy reuse on a number of
232 platforms, including embedded systems. I don't intend to convert to
233 C++.</p>
234 <p>There is however a C++ wrapper provided by Ari Johnson
Daniel Veillarde9202a02000-10-16 16:58:19 +0000[diff] [blame]235 &lt;ari@btigate.com&gt; which may fullfill your needs:</p>
Daniel Veillardaf743792000-07-01 11:49:28 +0000[diff] [blame]236 <p>Website: <a
237 href="http://lusis.org/~ari/xml++/">http://lusis.org/~ari/xml++/</a></p>
238 <p>Download: <a
239 href="http://lusis.org/~ari/xml++/libxml++.tar.gz">http://lusis.org/~ari/xml++/libxml++.tar.gz</a></p>
240 </li>
241 <li>How to validate a document a posteriori ?
242 <p>It is possible to validate documents which had not been validated at
243 initial parsing time or documents who have been built from scratch using
244 the API. Use the <a
Daniel Veillard9cb5ff42001-01-29 08:22:21 +0000[diff] [blame]245 href="http://xmlsoft.org/html/libxml-valid.html#XMLVALIDATEDTD">xmlValidateDtd()</a>
Daniel Veillardaf743792000-07-01 11:49:28 +0000[diff] [blame]246 function. It is also possible to simply add a Dtd to an existing
247 document:</p>
248 <pre>xmlDocPtr doc; /* your existing document */
249 xmlDtdPtr dtd = xmlParseDTD(NULL, filename_of_dtd); /* parse the DTD */
Daniel Veillarde9202a02000-10-16 16:58:19 +0000[diff] [blame]250 dtd-&gt;name = xmlStrDup((xmlChar*)"root_name"); /* use the given root */
Daniel Veillardaf743792000-07-01 11:49:28 +0000[diff] [blame]251
Daniel Veillarde9202a02000-10-16 16:58:19 +0000[diff] [blame]252 doc-&gt;intSubset = dtd;
253 if (doc-&gt;children == NULL) xmlAddChild((xmlNodePtr)doc, (xmlNodePtr)dtd);
254 else xmlAddPrevSibling(doc-&gt;children, (xmlNodePtr)dtd);
Daniel Veillardaf743792000-07-01 11:49:28 +0000[diff] [blame]255 </pre>
256 </li>
257 <li>etc ...</li>
258</ol>
259
260<p><a href="mailto:Daniel.Veillard@w3.org">Daniel Veillard</a></p>
261
262<p>$Id$</p>
263</body>
264</html>