WSO2 Web Services Framework for PHP (WSO2 WSF/PHP) is an open-source, enterprise grade PHP extension for providing and consuming web services in PHP. The home page for the project can be found at http://wso2.org/projects/wsf/php. WSO2 WSF/PHP is a complete solution for building and deploying web services and is the only PHP extension with the widest range of WS-* (also known as SOAP web services) specification implementations. It is also notable that it has a comprehensive REST support. You can implement a single service and expose it as both SOAP and REST service. Please refer to Chapter 1 for a recap of REST and SOAP comparison.

In Chapter 6 we introduced Zend Framework. The key difference between WSF/PHP and the Zend Framework is that, while Zend framework is a library written in PHP, WSF/PHP is a library written in C as a PHP extension. Also, while Zend Framework is a generic PHP library that also includes REST support. WSF/PHP is a web services specific framework that supports REST as well as SOAP services. You can use WSF/PHP as a REST framework alone or you can use it for SOAP web services that require quality of service aspects such as security and reliability.

Since WSF/PHP is implemented in C, you can expect to have better performance while using it as compared to using a library written in PHP alone such as Zend Framework. However, the performance gain comes with a cost, that being the complexity of installing compiled C libraries as a PHP extension. Whereas a library written in PHP, such as Zend Framework, can be just copied to the document root and you are ready to use it.