Classified as "the most popular Apache module" by E-Soft, PHP is one of the least frequently mentioned languages amongst the XML discussion lists.

Yet PHP was among the first languages to support XML (since release 3.0.6, December 98 using James Clark's expat library).

Although this feature is sufficient to parse a XML document, the limitations of the object oriented features of PHP3 didn't allow for an easy implementation of any DOM interface, and the function libraries developed for XML have always been very proprietary and limited.

PHP4 (of which beta4 patch level 1 looks very stable) brings many enhancements to PHP's object oriented features and should therefore allow a leap forward in the XML direction.

Uwe Steinmann is currently developing a new extension for PHP4 (domxml). According to the source code provided with beta4 patch level 1, this extension sounds to be a simpler version of the W3C DOM .

Another extension which is eagerly expected for PHP4, developed by Sam Ruby, is support for Java objects. This extension implements an access to Java from PHP and should allow use of all the Java libraries -- such as the many XML parsers and XSL translators.

Finally, a debate started by Lukasz Felsztukier on the php4beta@lists.php.net mailing list has initiated discussion on the direct support of XSLT within PHP. Despite the views of PHP users that "doing XML-XSL processing to serve pages at online time is a waste of performance", the suggestion to use a "mature" version of Xalan-C has been welcomed by PHP4 developer Andi Gutmans.

Stay tuned, PHP is moving on towards XML.

To learn more:

• PHP home page: PHP: Hypertext Preprocessor.
• PHP / XML user documentation: XML parser functions.
• E-Soft home site: E-Soft.
• Apache modules: Apache Module Report.
• 2 examples of XML PHP3 libraries: Upper Design, downl oads.dyomedea.com.
• php4beta@lists.php.net archives: PHP4 Beta talk.
• Debate started by Lukasz Felsztukier: Can PHP do XML + XSL = HTML stuff?