Database plays a big role in any day-today application. It is a major component from accounting, web portal, CMS, SaaS applications, search engines to all enterprise applications. In traditional MVC(Model-View-Controller) applications we talk about the Model component which represent the database.. And in 3-tier architectural pattern it is the ‘Data layer’ which represent the database and provide data to the ‘Logic Layer’ as per request.
As SOA evolves, database is becoming just one part of the ‘Data Layer’ or the ‘Model’ component. There are many data sources, data providers which are mostly deployed as web services which you can ask for data as you do with traditional databases. This gives you the advantages of the use of web services like interoperability, security and reliability and other WS-* support. And it helps you to get rid of the headache of installing different drivers for different databases and most importantly it removes the tight binding of your application to the database. So with adaption of SOA, the ‘Data Layer’ has been replaced by the ‘Service Consuming Layer’.
The story of the ‘Data Provider’ also changed with the SOA adaption. The new data sources are designed with the SOA in mind. And the legacy systems are wrapped by a service layer to make it more easier to consume. We use the term ‘Data Services’ for the data sources deployed as web services.
There are many public data services available as ‘REST’ which is a lighter way of providing services. The other way is the use of WS-* features like WS-Security, WS-Reliable Messaging to deploy the data services which are mostly adopted by the enterprise.
Today there are many tools around, that helps you to develop data services from existing databases. WSO2 provides an open source data service framework that allows you to build data services from simple xml configuration files without the need of writing a single line of code. And WSF/PHP also packed with a data services library that allow you to write a simple PHP script to build a data service.
PHP is one of the favorite language to write database back-ended web applications. Specially considering the fact that there are thousands of servers powered by the LAMP (Linux + Apache + MySQL +PHP) stack, PHP data service library would comes useful to build around a web service around these existing data sources and make them SOA-aware.