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<html xmlns="http://www.w3.org/1999/xhtml"><head><meta http-equiv="Content-Type" content="text/html; charset=UTF-8" /><link rel="SHORTCUT ICON" href="/favicon.ico" /><style type="text/css">
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TD {font-family: Verdana,Arial,Helvetica}
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BODY {font-family: Verdana,Arial,Helvetica; margin-top: 2em; margin-left: 0em; margin-right: 0em}
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H1 {font-family: Verdana,Arial,Helvetica}
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H2 {font-family: Verdana,Arial,Helvetica}
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H3 {font-family: Verdana,Arial,Helvetica}
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A:link, A:visited, A:active { text-decoration: underline }
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</style><title>FAQ</title></head><body bgcolor="#8b7765" text="#000000" link="#a06060" vlink="#000000"> |    | The XML C parser and toolkit of GnomeFAQ |
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| <center>Main Menu</center> | | <form action="search.php" enctype="application/x-www-form-urlencoded" method="get"><input name="query" type="text" size="20" value="" /><input name="submit" type="submit" value="Search ..." /></form> |
| <center>Related links</center> | |
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License(s)
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Installation
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Compilation
|
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Developer corner
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Licensing Terms for libxml
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libxml2 is released under the MIT
|
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License; see the file Copyright in the distribution for the precise
|
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wording
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Can I embed libxml2 in a proprietary application ?
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Yes. The MIT License allows you to keep proprietary the changes you
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made to libxml, but it would be graceful to send-back bug fixes and
|
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improvements as patches for possible incorporation in the main
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development tree.
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Do Not Use
|
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libxml1, use libxml2
|
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|
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Where can I get libxml ?
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The original distribution comes from xmlsoft.org or gnome.org
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Most Linux and BSD distributions include libxml, this is probably the
|
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safer way for end-users to use libxml.
|
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David Doolin provides precompiled Windows versions at http://www.ce.berkeley.edu/~doolin/code/libxmlwin32/
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I see libxml and libxml2 releases, which one should I install ?
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If you are not constrained by backward compatibility issues with
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existing applications, install libxml2 only
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If you are not doing development, you can safely install both.
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Usually the packages libxml and libxml2 are
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compatible (this is not the case for development packages).
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If you are a developer and your system provides separate packaging
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for shared libraries and the development components, it is possible
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to install libxml and libxml2, and also libxml-devel
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and libxml2-devel
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too for libxml2 >= 2.3.0
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If you are developing a new application, please develop against
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libxml2(-devel)
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I can't install the libxml package, it conflicts with libxml0
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You probably have an old libxml0 package used to provide the shared
|
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library for libxml.so.0, you can probably safely remove it. The libxml
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packages provided on xmlsoft.org provide
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libxml.so.0
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I can't install the libxml(2) RPM package due to failed
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dependencies
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The most generic solution is to re-fetch the latest src.rpm , and
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rebuild it locally with
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rpm --rebuild libxml(2)-xxx.src.rpm.
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If everything goes well it will generate two binary rpm packages (one
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providing the shared libs and xmllint, and the other one, the -devel
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package, providing includes, static libraries and scripts needed to build
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applications with libxml(2)) that you can install locally.
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What is the process to compile libxml2 ?
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As most UNIX libraries libxml2 follows the "standard":
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gunzip -c xxx.tar.gz | tar xvf -
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cd libxml-xxxx
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./configure --help
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to see the options, then the compilation/installation proper
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./configure [possible options]
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make
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make install
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At that point you may have to rerun ldconfig or a similar utility to
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update your list of installed shared libs.
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What other libraries are needed to compile/install libxml2 ?
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Libxml2 does not require any other library, the normal C ANSI API
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should be sufficient (please report any violation to this rule you may
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find).
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However if found at configuration time libxml2 will detect and use the
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following libs:
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libz : a
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highly portable and available widely compression library.
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iconv: a powerful character encoding conversion library. It is
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included by default in recent glibc libraries, so it doesn't need to
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be installed specifically on Linux. It now seems a part
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of the official UNIX specification. Here is one implementation of the
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library which source can be found here.
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Make check fails on some platforms
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Sometimes the regression tests' results don't completely match the
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value produced by the parser, and the makefile uses diff to print the
|
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delta. On some platforms the diff return breaks the compilation process;
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if the diff is small this is probably not a serious problem.
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Sometimes (especially on Solaris) make checks fail due to limitations
|
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in make. Try using GNU-make instead.
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I use the SVN version and there is no configure script
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The configure script (and other Makefiles) are generated. Use the
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autogen.sh script to regenerate the configure script and Makefiles,
|
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like:
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./autogen.sh --prefix=/usr --disable-shared
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|
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I have troubles when running make tests with gcc-3.0
|
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It seems the initial release of gcc-3.0 has a problem with the
|
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optimizer which miscompiles the URI module. Please use another
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compiler.
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Troubles compiling or linking programs using libxml2
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Usually the problem comes from the fact that the compiler doesn't get
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the right compilation or linking flags. There is a small shell script
|
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xml2-config which is installed as part of libxml2 usual
|
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install process which provides those flags. Use
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xml2-config --cflags
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to get the compilation flags and
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xml2-config --libs
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to get the linker flags. Usually this is done directly from the
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Makefile as:
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CFLAGS=`xml2-config --cflags`
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LIBS=`xml2-config --libs`
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|
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I want to install my own copy of libxml2 in my home directory and
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link my programs against it, but it doesn't work
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There are many different ways to accomplish this. Here is one way to
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do this under Linux. Suppose your home directory is /home/user.
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Then:
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|
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Create a subdirectory, let's call it myxml
|
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unpack the libxml2 distribution into that subdirectory
|
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chdir into the unpacked distribution
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(/home/user/myxml/libxml2 )
|
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configure the library using the "--prefix" switch,
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specifying an installation subdirectory in
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/home/user/myxml, e.g.
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./configure --prefix /home/user/myxml/xmlinst {other
|
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configuration options}
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|
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now run make followed by make install
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At this point, the installation subdirectory contains the complete
|
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"private" include files, library files and binary program files (e.g.
|
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xmllint), located in
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/home/user/myxml/xmlinst/lib,
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/home/user/myxml/xmlinst/include and
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/home/user/myxml/xmlinst/bin
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respectively.
|
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In order to use this "private" library, you should first add it to
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the beginning of your default PATH (so that your own private program
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files such as xmllint will be used instead of the normal system
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ones). To do this, the Bash command would be
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export PATH=/home/user/myxml/xmlinst/bin:$PATH
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|
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Now suppose you have a program test1.c that you would
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like to compile with your "private" library. Simply compile it using
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the command
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gcc `xml2-config --cflags --libs` -o test test.c
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Note that, because your PATH has been set with
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/home/user/myxml/xmlinst/bin at the beginning, the xml2-config
|
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program which you just installed will be used instead of the system
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default one, and this will automatically get the correct
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libraries linked with your program.
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xmlDocDump() generates output on one line.
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Libxml2 will not invent spaces in the content of a
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document since all spaces in the content of a document are
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significant. If you build a tree from the API and want
|
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indentation:
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|
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the correct way is to generate those yourself too.
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the dangerous way is to ask libxml2 to add those blanks to your
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content modifying the content of your document in the
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process. The result may not be what you expect. There is
|
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NO way to guarantee that such a modification won't
|
|
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affect other parts of the content of your document. See xmlKeepBlanksDefault
|
|
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() and xmlSaveFormatFile
|
|
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()
|
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|
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|
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Extra nodes in the document:
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For an XML file as below:
|
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<?xml version="1.0"?>
|
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<PLAN xmlns="http://www.argus.ca/autotest/1.0/">
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<NODE CommFlag="0"/>
|
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<NODE CommFlag="1"/>
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</PLAN>
|
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after parsing it with the function
|
|
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pxmlDoc=xmlParseFile(...);
|
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I want to the get the content of the first node (node with the
|
|
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CommFlag="0")
|
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so I did it as following;
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xmlNodePtr pnode;
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pnode=pxmlDoc->children->children;
|
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but it does not work. If I change it to
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|
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pnode=pxmlDoc->children->children->next;
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then it works. Can someone explain it to me.
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|
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In XML all characters in the content of the document are significant
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including blanks and formatting line breaks.
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The extra nodes you are wondering about are just that, text nodes with
|
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the formatting spaces which are part of the document but that people tend
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|
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to forget. There is a function xmlKeepBlanksDefault
|
|
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() to remove those at parse time, but that's an heuristic, and its
|
|
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use should be limited to cases where you are certain there is no
|
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mixed-content in the document.
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|
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I get compilation errors of existing code like when accessing
|
|
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root or child fields of nodes.
|
|
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You are compiling code developed for libxml version 1 and using a
|
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libxml2 development environment. Either switch back to libxml v1 devel or
|
|
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even better fix the code to compile with libxml2 (or both) by following the instructions.
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|
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I get compilation errors about non existing
|
|
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xmlRootNode or xmlChildrenNode
|
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fields.
|
|
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The source code you are using has been upgraded to be able to compile with both libxml
|
|
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and libxml2, but you need to install a more recent version:
|
|
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libxml(-devel) >= 1.8.8 or libxml2(-devel) >= 2.1.0
|
|
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|
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Random crashes in threaded applications
|
|
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Read and follow all advices on the thread
|
|
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safety page, and make 100% sure you never call xmlCleanupParser()
|
|
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while the library or an XML document might still be in use by another
|
|
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thread.
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|
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The example provided in the web page does not compile.
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It's hard to maintain the documentation in sync with the code
|
|
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<grin/> ...
|
|
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Check the previous points 1/ and 2/ raised before, and please send
|
|
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patches.
|
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|
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Where can I get more examples and information than provided on the
|
|
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web page?
|
|
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Ideally a libxml2 book would be nice. I have no such plan ... But you
|
|
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can:
|
|
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|
|
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check more deeply the existing
|
|
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generated doc
|
|
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have a look at the set of
|
|
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examples.
|
|
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look for examples of use for libxml2 function using the Gnome code
|
|
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or by asking on Google.
|
|
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Browse
|
|
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the libxml2 source , I try to write code as clean and documented
|
|
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as possible, so looking at it may be helpful. In particular the code
|
|
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of xmllint.c and of the various testXXX.c test programs should
|
|
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provide good examples of how to do things with the library.
|
|
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|
|
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|
|
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|
|
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What about C++ ?
|
|
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libxml2 is written in pure C in order to allow easy reuse on a number
|
|
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of platforms, including embedded systems. I don't intend to convert to
|
|
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C++.
|
|
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There is however a C++ wrapper which may fulfill your needs:
|
|
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|
|
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by Ari Johnson <ari@btigate.com>:
|
|
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Website: http://libxmlplusplus.sourceforge.net/
|
|
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Download: http://sourceforge.net/project/showfiles.php?group_id=12999
|
|
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|
|
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|
|
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|
|
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How to validate a document a posteriori ?
|
|
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It is possible to validate documents which had not been validated at
|
|
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initial parsing time or documents which have been built from scratch
|
|
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using the API. Use the xmlValidateDtd()
|
|
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function. It is also possible to simply add a DTD to an existing
|
|
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document:
|
|
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xmlDocPtr doc; /* your existing document */
|
|
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xmlDtdPtr dtd = xmlParseDTD(NULL, filename_of_dtd); /* parse the DTD */
|
|
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|
|
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dtd->name = xmlStrDup((xmlChar*)"root_name"); /* use the given root */
|
|
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|
|
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doc->intSubset = dtd;
|
|
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if (doc->children == NULL) xmlAddChild((xmlNodePtr)doc, (xmlNodePtr)dtd);
|
|
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else xmlAddPrevSibling(doc->children, (xmlNodePtr)dtd);
|
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So what is this funky "xmlChar" used all the time?
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It is a null terminated sequence of utf-8 characters. And only utf-8!
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You need to convert strings encoded in different ways to utf-8 before
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passing them to the API. This can be accomplished with the iconv library
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for instance.
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etc ...
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Daniel Veillard </body></html>
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