Application servers offer developers an integrated Web development environment that allows them to connect and manage a variety of enterprise resources such as Web servers, databases, and legacy application systems.

Application servers interface directly with the web server and the backend systems, they are where the business logic of web based applications that access enterprise resources is embedded.

The application server is, in many ways, not a new idea. People have for many years been doing with CGI web applications many of the tasks that application servers now handle. The difference with application servers is that they are far more scaleable, better performing, more robust and far more secure.

They also offer a far better development time return for e-business application development and deployment. As many common web programming tasks are tackled repeatedly, in many applications developers can re-use the components developed to handle those tasks. Xoology application servers also allow you to use low(er) cost development resources, in the shape of JavaScript programmers rather than Java, to develop e-business applications.

The flexibility and time savings inherent in using a good application server lends them to rapid prototyping of applications, an essential feature in a business world where development requirements, driven by real business needs, often change on the fly.

An application server provides both the development tools and runtime platform for delivering applications on the web. A typical application server will offer security and state management and database connectivity.

Advanced servers such as Concerto will also offer load balancing, failover and security features as well as interactive debugging and the facility to re-use tried and tested code components, cutting development time on projects.

A User (Client) sends an information request from a web browser. This could be using a PC based browser or some other means such as a WAP phone or PDA.

The information request is sent to a webserver via the relevant network medium, this could be the internet, an intranet or extranet.

The webserver receives the information request from the network. The web server handles requests for traditional static pages and passes on any requests for dynamic pages to the Application server.

The Application server, in line with business rules, extracts information from a variety of data sources to fulfill the request (these could be back office data sources including legacy systems) and feeds the results back to the web server for passing on to the requesting client.