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| <h1>The XML C library for Gnome</h1> |
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| <li><a href="http://mail.gnome.org/archives/xml/">Mail archive</a></li> |
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| <p>Table of Content:</p> |
| <ul> |
| <li><a href="FAQ.html#License">License(s)</a></li> |
| <li><a href="FAQ.html#Installati">Installation</a></li> |
| <li><a href="FAQ.html#Compilatio">Compilation</a></li> |
| <li><a href="FAQ.html#Developer">Developer corner</a></li> |
| </ul> |
| <h3> |
| <a name="License">License</a>(s)</h3> |
| <ol> |
| <li> |
| <em>Licensing Terms for libxml</em> |
| <p>libxml is released under the <a href="http://www.opensource.org/licenses/mit-license.html">MIT |
| License</a>, see the file Copyright in the distribution for the precise |
| wording</p> |
| </li> |
| <li> |
| <em>Can I embed libxml in a proprietary application ?</em> |
| <p>Yes. The MIT License allows you to also keep proprietary the changes |
| you made to libxml, but it would be graceful to provide back bug fixes |
| and improvements as patches for possible incorporation in the main |
| development tree</p> |
| </li> |
| </ol> |
| <h3><a name="Installati">Installation</a></h3> |
| <ol> |
| <li>Unless you are forced to because your application links with a Gnome |
| library requiring it, <strong><span style="background-color: #FF0000">Do |
| Not Use libxml1</span></strong>, use libxml2</li> |
| <li> |
| <em>Where can I get libxml</em> ? |
| <p>The original distribution comes from <a href="ftp://rpmfind.net/pub/libxml/">rpmfind.net</a> or <a href="ftp://ftp.gnome.org/pub/GNOME/stable/sources/libxml/">gnome.org</a> |
| </p> |
| <p>Most Linux and BSD distributions include libxml, this is probably the |
| safer way for end-users</p> |
| <p>David Doolin provides precompiled Windows versions at <a href="http://www.ce.berkeley.edu/~doolin/code/libxmlwin32/ ">http://www.ce.berkeley.edu/~doolin/code/libxmlwin32/</a> |
| </p> |
| </li> |
| <li> |
| <em>I see libxml and libxml2 releases, which one should I install ?</em> |
| <ul> |
| <li>If you are not concerned by any existing backward compatibility |
| with existing application, install libxml2 only</li> |
| <li>If you are not doing development, you can safely install both. |
| usually the packages <a href="http://rpmfind.net/linux/RPM/libxml.html">libxml</a> and <a href="http://rpmfind.net/linux/RPM/libxml2.html">libxml2</a> are |
| compatible (this is not the case for development packages)</li> |
| <li>If you are a developer and your system provides separate packaging |
| for shared libraries and the development components, it is possible |
| to install libxml and libxml2, and also <a href="http://rpmfind.net/linux/RPM/libxml-devel.html">libxml-devel</a> |
| and <a href="http://rpmfind.net/linux/RPM/libxml2-devel.html">libxml2-devel</a> |
| too for libxml2 >= 2.3.0</li> |
| <li>If you are developing a new application, please develop against |
| libxml2(-devel)</li> |
| </ul> |
| </li> |
| <li> |
| <em>I can't install the libxml package it conflicts with libxml0</em> |
| <p>You probably have an old libxml0 package used to provide the shared |
| library for libxml.so.0, you can probably safely remove it. Anyway the |
| libxml packages provided on <a href="ftp://rpmfind.net/pub/libxml/">rpmfind.net</a> provides |
| libxml.so.0</p> |
| </li> |
| <li> |
| <em>I can't install the libxml(2) RPM package due to failed |
| dependencies</em> |
| <p>The most generic solution is to re-fetch the latest src.rpm , and |
| rebuild it locally with</p> |
| <p><code>rpm --rebuild libxml(2)-xxx.src.rpm</code></p> |
| <p>if everything goes well it will generate two binary rpm (one providing |
| the shared libs and xmllint, and the other one, the -devel package |
| providing includes, static libraries and scripts needed to build |
| applications with libxml(2)) that you can install locally.</p> |
| </li> |
| </ol> |
| <h3><a name="Compilatio">Compilation</a></h3> |
| <ol> |
| <li> |
| <em>What is the process to compile libxml ?</em> |
| <p>As most UNIX libraries libxml follows the "standard":</p> |
| <p><code>gunzip -c xxx.tar.gz | tar xvf -</code></p> |
| <p><code>cd libxml-xxxx</code></p> |
| <p><code>./configure --help</code></p> |
| <p>to see the options, then the compilation/installation proper</p> |
| <p><code>./configure [possible options]</code></p> |
| <p><code>make</code></p> |
| <p><code>make install</code></p> |
| <p>At that point you may have to rerun ldconfig or similar utility to |
| update your list of installed shared libs.</p> |
| </li> |
| <li> |
| <em>What other libraries are needed to compile/install libxml ?</em> |
| <p>Libxml does not requires any other library, the normal C ANSI API |
| should be sufficient (please report any violation to this rule you may |
| find).</p> |
| <p>However if found at configuration time libxml will detect and use the |
| following libs:</p> |
| <ul> |
| <li> |
| <a href="http://www.info-zip.org/pub/infozip/zlib/">libz</a> : a |
| highly portable and available widely compression library</li> |
| <li>iconv: a powerful character encoding conversion library. It's |
| included by default on recent glibc libraries, so it doesn't need to |
| be installed specifically on Linux. It seems it's now <a href="http://www.opennc.org/onlinepubs/7908799/xsh/iconv.html">part |
| of the official UNIX</a> specification. Here is one <a href="http://clisp.cons.org/~haible/packages-libiconv.html">implementation |
| of the library</a> which source can be found <a href="ftp://ftp.ilog.fr/pub/Users/haible/gnu/">here</a>.</li> |
| </ul> |
| </li> |
| <li> |
| <em>make check fails on some platforms</em> |
| <p>Sometime the regression tests results don't completely match the value |
| produced by the parser, and the makefile uses diff to print the delta. On |
| some platforms the diff return breaks the compilation process, if the |
| diff is small this is probably not a serious problem.</p> |
| <p>Sometimes (especially on Solaris) make checks fails due to limitations |
| in make. Try using GNU-make instead.</p> |
| </li> |
| <li> |
| <em>I use the CVS version and there is no configure script</em> |
| <p>The configure (and other Makefiles) are generated. Use the autogen.sh |
| script to regenerate the configure and Makefiles, like:</p> |
| <p><code>./autogen.sh --prefix=/usr --disable-shared</code></p> |
| </li> |
| <li> |
| <em>I have troubles when running make tests with gcc-3.0</em> |
| <p>It seems the initial release of gcc-3.0 has a problem with the |
| optimizer which miscompiles the URI module. Please use another |
| compiler</p> |
| </li> |
| </ol> |
| <h3> |
| <a name="Developer">Developer</a> corner</h3> |
| <ol> |
| <li> |
| <em>xmlDocDump() generates output on one line</em> |
| <p>libxml will not <strong>invent</strong> spaces in the content of a |
| document since <strong>all spaces in the content of a document are |
| significant</strong>. If you build a tree from the API and want |
| indentation:</p> |
| <ol> |
| <li>the correct way is to generate those yourself too</li> |
| <li>the dangerous way is to ask libxml to add those blanks to your |
| content <strong>modifying the content of your document in the |
| process</strong>. The result may not be what you expect. There is |
| <strong>NO</strong> way to guarantee that such a modification won't |
| impact other part of the content of your document. See <a href="http://xmlsoft.org/html/libxml-parser.html#XMLKEEPBLANKSDEFAULT">xmlKeepBlanksDefault |
| ()</a> and <a href="http://xmlsoft.org/html/libxml-tree.html#XMLSAVEFORMATFILE">xmlSaveFormatFile |
| ()</a> |
| </li> |
| </ol> |
| </li> |
| <li>Extra nodes in the document: |
| <p><em>For a XML file as below:</em></p> |
| <pre><?xml version="1.0"?> |
| <PLAN xmlns="http://www.argus.ca/autotest/1.0/"> |
| <NODE CommFlag="0"/> |
| <NODE CommFlag="1"/> |
| </PLAN></pre> |
| <p><em>after parsing it with the function |
| pxmlDoc=xmlParseFile(...);</em></p> |
| <p><em>I want to the get the content of the first node (node with the |
| CommFlag="0")</em></p> |
| <p><em>so I did it as following;</em></p> |
| <pre>xmlNodePtr pnode; |
| pnode=pxmlDoc->children->children;</pre> |
| <p><em>but it does not work. If I change it to</em></p> |
| <pre>pnode=pxmlDoc->children->children->next;</pre> |
| <p><em>then it works. Can someone explain it to me.</em></p> |
| <p> |
| <p>In XML all characters in the content of the document are significant |
| <strong>including blanks and formatting line breaks</strong>.</p> |
| <p>The extra nodes you are wondering about are just that, text nodes with |
| the formatting spaces which are part of the document but that people tend |
| to forget. There is a function <a href="http://xmlsoft.org/html/libxml-parser.html">xmlKeepBlanksDefault |
| ()</a> to remove those at parse time, but that's an heuristic, and its |
| use should be limited to case where you are sure there is no |
| mixed-content in the document.</p> |
| </li> |
| <li> |
| <em>I get compilation errors of existing code like when accessing |
| <strong>root</strong> or <strong>childs fields</strong> of nodes</em> |
| <p>You are compiling code developed for libxml version 1 and using a |
| libxml2 development environment. Either switch back to libxml v1 devel or |
| even better fix the code to compile with libxml2 (or both) by <a href="upgrade.html">following the instructions</a>.</p> |
| </li> |
| <li> |
| <em>I get compilation errors about non existing |
| <strong>xmlRootNode</strong> or <strong>xmlChildrenNode</strong> |
| fields</em> |
| <p>The source code you are using has been <a href="upgrade.html">upgraded</a> to be able to compile with both libxml |
| and libxml2, but you need to install a more recent version: |
| libxml(-devel) >= 1.8.8 or libxml2(-devel) >= 2.1.0</p> |
| </li> |
| <li> |
| <em>XPath implementation looks seriously broken</em> |
| <p>XPath implementation prior to 2.3.0 was really incomplete, upgrade to |
| a recent version, there is no known bug in the current version.</p> |
| </li> |
| <li> |
| <em>The example provided in the web page does not compile</em> |
| <p>It's hard to maintain the documentation in sync with the code |
| <grin/> ...</p> |
| <p>Check the previous points 1/ and 2/ raised before, and send |
| patches.</p> |
| </li> |
| <li> |
| <em>Where can I get more examples and informations than in the web |
| page</em> |
| <p>Ideally a libxml book would be nice. I have no such plan ... But you |
| can:</p> |
| <ul> |
| <li>check more deeply the <a href="html/libxml-lib.html">existing |
| generated doc</a> |
| </li> |
| <li>looks for examples of use for libxml function using the Gnome code |
| for example the following will query the full Gnome CVS base for the |
| use of the <strong>xmlAddChild()</strong> function: |
| <p><a href="http://cvs.gnome.org/lxr/search?string=xmlAddChild">http://cvs.gnome.org/lxr/search?string=xmlAddChild</a></p> |
| <p>This may be slow, a large hardware donation to the gnome project |
| could cure this :-)</p> |
| </li> |
| <li> |
| <a href="http://cvs.gnome.org/bonsai/rview.cgi?cvsroot=/cvs/gnome&dir=gnome-xml">Browse |
| the libxml source</a> , I try to write code as clean and documented |
| as possible, so looking at it may be helpful. Especially the code of |
| xmllint.c and of the various testXXX.c tests programs should provide |
| good example on how to do things with the library.</li> |
| </ul> |
| </li> |
| <li>What about C++ ? |
| <p>libxml is written in pure C in order to allow easy reuse on a number |
| of platforms, including embedded systems. I don't intend to convert to |
| C++.</p> |
| <p>There is however a few C++ wrappers which may fulfill your needs:</p> |
| <ul> |
| <li>by Ari Johnson <ari@btigate.com>: |
| <p>Website: <a href="http://lusis.org/~ari/xml++/">http://lusis.org/~ari/xml++/</a> |
| </p> |
| <p>Download: <a href="http://lusis.org/~ari/xml++/libxml++.tar.gz">http://lusis.org/~ari/xml++/libxml++.tar.gz</a> |
| </p> |
| </li> |
| <li>by Peter Jones <pjones@pmade.org> |
| <p>Website: <a href="http://pmade.org/pjones/software/xmlwrapp/">http://pmade.org/pjones/software/xmlwrapp/</a> |
| </p> |
| </li> |
| </ul> |
| </li> |
| <li>How to validate a document a posteriori ? |
| <p>It is possible to validate documents which had not been validated at |
| initial parsing time or documents who have been built from scratch using |
| the API. Use the <a href="http://xmlsoft.org/html/libxml-valid.html#XMLVALIDATEDTD">xmlValidateDtd()</a> |
| function. It is also possible to simply add a DTD to an existing |
| document:</p> |
| <pre>xmlDocPtr doc; /* your existing document */ |
| xmlDtdPtr dtd = xmlParseDTD(NULL, filename_of_dtd); /* parse the DTD */ |
| dtd->name = xmlStrDup((xmlChar*)"root_name"); /* use the given root */ |
| |
| doc->intSubset = dtd; |
| if (doc->children == NULL) xmlAddChild((xmlNodePtr)doc, (xmlNodePtr)dtd); |
| else xmlAddPrevSibling(doc->children, (xmlNodePtr)dtd); |
| </pre> |
| </li> |
| <li>etc ...</li> |
| </ol> |
| <p> |
| <p><a href="bugs.html">Daniel Veillard</a></p> |
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