Nick Vidal

The Web is evolving rapidly and Web applications are starting to reach the same level of functionality of desktop applications. Perhaps we can even risk to say that Web applications will soon surpass desktop applications in functionality given the interconnected and ubiquitous nature of the Web. Despite the differences among Web browsers, there has been an increasing convergence of standards and practices, mostly promoted by the W3C (World Wide Web Consortium) and the Ecma International. The emergence of powerful JavaScript frameworks has also tremendously helped developers to abstract beyond these differences and create rich internet applications easier and faster. Soon, users will be able to access Web applications much like they access desktop applications by using a Webtop, i.e. a desktop that runs on top of the Web browser.

In the server-side, we have seen a consolidation of the LAMP stack and its derivatives, which consists of an Operating System, a Web Server, a Scripting Language and a Database. On top of this stack we have seen the emergence of Web frameworks for managing content, users, applications and services. Notice that traditionally the management of these has been the responsibility of Operating Systems. However, this responsibility is being delegated up the stack so that it can benefit from the key aspects of the Web. This trend will ultimately lead to a WebOS, i.e. an Operating System that runs on top of the Web server.

The figure below illustrates this evolving architecture. The main goal of this publication is to explain how to develop Web services and applications following this architectural design. More specifically, the objective of this publication is to to explain how to develop Web services and applications using the ExtJS framework as a Webtop and the Drupal framework as a WebOS.

Web Architecture - towards the Webtop and WebOS.

There has been some interesting developments combining Drupal and Flex. Drupal is an excellent CMS (Content Management System), while Flex is a great technology for building RIA (Rich Internet Applications). Using Drupal as a backend and Flex as a frontend, it’s possible to achieve outstanding results.

An alternative to Flex is AJAX. JavaScript libraries are becoming mature, and since JavaScript interpretation is native to browsers, the use of AJAX is an attractive solution. One fine example of what can be accomplished with AJAX is the Ext JS library. With Ext, it’s possible to emulate quite nicely a Desktop on the Web.

To create a Web Desktop using Drupal as a backend and Ext as a frontend, we need to use the Services module. The Services module allows a Drupal site to provide Web services via multiple interfaces while using the same callback code. The AMFPHP module may be used by Flex applications, while the JSON server module may be used by Ext applications.