WSO2 for PHP is a Web Services framework that works as a PHP extension and provides support for key WS-* specifications. Using this framework one can easily create server and client side Web Service applications that can easily integrate with Java or .NET systems (which are both the most common languages used for building Web Services).
Installation of this framework on most linux systems used to be easier on earlier versions of WSO2 when rpm and deb packages were available for download. This is not the case anymore.
the atRiaS Blog 