Introduction

This module implements a Perl interface to the Gnome libxml2 library which provides interfaces for parsing and manipulating XML files. This module allows Perl programmers to make use of its highly capable validating XML parser and its high performance DOM implementation.

Important Notes

XML::LibXML was almost entirely reimplemented between version 1.40 to version 1.49. This may cause problems on some production machines. With version 1.50 a lot of compatibility fixes were applied, so programs written for XML::LibXML 1.40 or less should run with version 1.50 again.

In 1.59, a new callback API was introduced. This new API is not compatible with the previous one. See XML::LibXML::InputCallback manual page for details.

In 1.61 the XML::LibXML::XPathContext module, previously distributed separately, was merged in.

An experimental support for Perl threads introduced in 1.66 has been replaced in 1.67.

Dependencies

Prior to installation you MUST have installed the libxml2 library. You can get the latest libxml2 version from https://gitlab.gnome.org/GNOME/libxml2.

Without libxml2 installed this module will neither build nor run.

Also XML::LibXML requires the following packages:

• XML::SAX — base class for SAX parsers
• XML::NamespaceSupport — namespace support for SAX parsers

These packages are required. If one is missing some tests will fail.

Again, libxml2 is required to make XML::LibXML work. The library is not just required to build XML::LibXML, it has to be accessible during run-time as well. Because of this you need to make sure libxml2 is installed properly. To test this, run the xmllint program on your system. xmllint is shipped with libxml2 and therefore should be available. For building the module you will also need the header file for libxml2, which in binary (.rpm, .deb) etc. distributions usually dwell in a package named libxml2-devel or similar.

Installation

(These instructions are for UNIX and GNU/Linux systems. For MSWin32, see Notes for Microsoft Windows below.)

To install XML::LibXML just follow the standard installation routine for Perl modules:

perl Makefile.PL
make
make test
make install   # as superuser

Note that XML::LibXML is an XS based Perl extension and you need a C compiler to build it.

Note also that you should rebuild XML::LibXML if you upgrade libxml2 in order to avoid problems with possible binary incompatibilities between releases of the library.

Notes on libxml2 versions

XML::LibXML requires at least libxml2 2.6.16 to compile and pass all tests and at least 2.6.21 is required for XML::LibXML::Reader. For some older OS versions this means that an update of the pre-built packages is required.

Although libxml2 claims binary compatibility between its patch levels, it is a good idea to recompile XML::LibXML and run its tests after an upgrade of libxml2.

If your libxml2 installation is not within your $PATH, you can pass the XMLPREFIX=$YOURLIBXMLPREFIX parameter to Makefile.PL determining the correct libxml2 version in use. e.g.

perl Makefile.PL XMLPREFIX=/usr/brand-new

will ask /usr/brand-new/bin/xml2-config about your real libxml2 configuration.

Try to avoid setting INC and LIBS directly on the command-line, for if used, Makefile.PL does not check the libxml2 version for compatibility with XML::LibXML.

Which version of libxml2 should be used?

XML::LibXML is tested against a couple versions of libxml2 before it is released. Thus there are versions of libxml2 that are known not to work properly with XML::LibXML. The Makefile.PL keeps a blacklist of the incompatible libxml2 versions using Alien::Libxml2. The blacklist itself is kept inside its alienfile file.

If Makefile.PL detects one of the incompatible versions, it notifies the user. It may still happen that XML::LibXML builds and pass its tests with such a version, but that does not mean everything is OK. There will be no support at all for blacklisted versions!

As of XML::LibXML 1.61, only versions 2.6.16 and higher are supported. XML::LibXML will probably not compile with earlier libxml2 versions than 2.5.6. Versions prior to 2.6.8 are known to be broken for various reasons, versions prior to 2.1.16 exhibit problems with namespaced attributes and do not therefore pass XML::LibXML regression tests.

It may happen that an unsupported version of libxml2 passes all tests under certain conditions. This is no reason to assume that it shall work without problems. If Makefile.PL marks a version of libxml2 as incompatible or broken it is done for a good reason.

Full linking information for libxml2 can be obtained by invoking xml2-config --libs.

Notes for Microsoft Windows

On Windows, the recommended way to install XML::LibXML is via Strawberry Perl, which ships with a working toolchain and pulls in libxml2 automatically through Alien::Libxml2.

If you need to build against a custom libxml2, pre-built Windows binaries are available from https://www.zlatkovic.com/pub/libxml/.

Notes for macOS

XML::LibXML builds and runs on supported versions of macOS. libxml2 is generally available either via the system, Homebrew (brew install libxml2), or installed automatically by Alien::Libxml2.

Notes for HPUX

XML::LibXML requires libxml2 2.6.16 or later. There may not exist a usable binary libxml2 package for HPUX and XML::LibXML. If HPUX cc does not compile libxml2 correctly, you will be forced to recompile perl with gcc (unless you have already done that).

Additionally I received the following Note from Rozi Kovesdi:

Here is my report if someone else runs into the same problem:

Finally I am done with installing all the libraries and XML Perl modules

The combination that worked best for me was: gcc GNU make

Most importantly - before trying to install Perl modules that depend on libxml2:

must set SHLIB_PATH to include the path to libxml2 shared library

assuming that you used the default:

export SHLIB=/usr/local/lib

also, make sure that the config files have execute permission:

/usr/local/bin/xml2-config
/usr/local/bin/xslt-config

they did not have +x after they were installed by make install and it took me a while to realize that this was my problem

or one can use:

perl Makefile.PL LIBS='-L/path/to/lib' INC='-I/path/to/include'

Contact

For bug reports and pull requests, please use the issue tracker at https://github.com/cpan-authors/XML-LibXML/issues.

Package History

• Versions < 0.98 were maintained by Matt Sergeant
• Versions 0.98 – 1.49 were maintained by Matt Sergeant and Christian Glahn
• Versions 1.49 – 1.56 were maintained by Christian Glahn
• Versions 1.56 – 1.58 were co-maintained by Petr Pajas
• Versions 1.59 onward were originally maintained by Petr Pajas
• Subsequently maintained for many years by Shlomi Fish (last release: 2.0210, January 2024)
• Now maintained by the cpan-authors team at https://github.com/cpan-authors/XML-LibXML

Patches and Developer Version

As XML::LibXML is open source software, help and patches are appreciated. If you find a bug in the current release, make sure this bug still exists in the developer version of XML::LibXML. This version can be cloned from its Git repository. For more information about that, see:

https://github.com/cpan-authors/XML-LibXML

Please consider all regression tests as correct. If any test fails it is most certainly related to a bug.

If you find documentation bugs, please fix them in the libxml.dbk file, stored in the docs directory.