Libxml Frequently Asqued Questions

Location: http://xmlsoft.org/FAQ.html

Libxml home page: http://xmlsoft.org/

Mailing-list archive: http://xmlsoft.org/messages/

Version: $Revision$

Table of Content:

Licence(s)

  1. Licensing Terms for libxml

    libxml is released under 2 (compatible) licences:

  2. Can I embed libxml in a proprietary application ?

    Yes. The W3C IPR allows you to also keep proprietary the changes you made to libxml, but it would be graceful to provide back bugfixes and improvements as patches for possible incorporation in the main developement tree

Installation

  1. Where can I get libxml ?

    The original distribution comes from rpmfind.net or gnome.org

    Most linux and Bsd distribution includes libxml, this is probably the safer way for end-users

    David Doolin provides precompiled Windows versions at http://www.ce.berkeley.edu/~doolin/code/libxmlwin32/

  2. I see libxml and libxml2 releases, which one should I install ?
  3. I can't install the libxml package it conflicts with libxml0

    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 rpmfind.net provides libxml.so.0

Compilation

  1. What is the process to compile libxml ?

    As most UNIX libraries libxml follows the "standard":

    gunzip -c xxx.tar.gz | tar xvf -

    cd libxml-xxxx

    ./configure --help

    to see the options, then the compilation/installation proper

    ./configure [possible options]

    make

    make install

    At that point you may have to rerun ldconfig or similar utility to update your list of installed shared libs.

  2. What other libraries are needed to compile/install libxml ?

    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).

    However if found at configuration time libxml will deect and use the following libs:

  3. The Makefile for the example gjobread is not generated

    This is due to a circular dependancy in automake. No solution found so far (if you know how to fix this the patch will be very welcome), that failure won't affect the actually building of the xml library. You can later go in and create the example Makefile by hand or reuse the following:

    CC=gcc
        CFLAGS=`xml-config --cflags`
        LDFLAGS=`xml-config --libs`

        all: gjobread

        clean:
        <TAB>@(rm -f gjobread gjobread.o)

        gjobread.o : gjobread.c
        <TAB>$(CC) $(CFLAGS) -c gjobread.c

        gjobread: gjobread.o
        <TAB>$(CC) -o gjobread gjobread.o $(LDFLAGS)
  4. libxml does not compile with HP-UX's optional ANSI-C compiler

    this is due to macro limitations. Try to add " -Wp,-H16800 -Ae" to the CFLAGS

    you can also install and use gcc instead or use a precompiled version of libxml, both available from the HP-UX Porting and Archive Centre

  5. make check fails on some platforms

    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

Developper corner

  1. I get compilation errors of existing code like when accessing root or childs fields of nodes

    You are compiling code developped for libxml version 1 and using a libxml2 developement environment. Either switch back to libxml v1 devel or even better fix the code to compile with libxml2 (or both) by following the instructions.

  2. I get compilation errors about non existing xmlRootNode or xmlChildrenNode fields

    The source code you are using has been upgraded 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

  3. XPath implementation looks seriously broken

    True, it's incomplete and the version released in 2.0.0 was nearly unusable. A set of patches from Picdar Technology have been integrated in 2.1.0 fixing the most nasty bugs. But there is still bugs and its incomplete. Patches and bug reports are welcome. This will be worked out, XPath implementation is not abandonned, just a momentary lack of time.

  4. The example provided in the web page does not compile

    It's hard to maintain the documentation in sync with the code <grin/> ...

    Check the previous points 1/ and 2/ raised before, and send patches.

  5. Where can I get more examples and informations than in the web page

    Ideally a libxml book would be nice. I have no such plan ... But you can:

  6. What about C++ ?

    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++.

    There is however a C++ wrapper provided by Ari Johnson <ari@btigate.com> which may fullfill your needs:

    Website: http://lusis.org/~ari/xml++/

    Download: http://lusis.org/~ari/xml++/libxml++.tar.gz

  7. How to validate a document a posteriori ?

    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 xmlValidateDtd() function. It is also possible to simply add a Dtd to an existing document:

    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);
  8. etc ...

Daniel Veillard

$Id$