Graphics by: Hema Sharma (NetAcross Ltd.)
The application server syncs and combines with the Web server for processing the request made by the client.
If we look at the request-response flow between client, Web server and application server, we come to know that the client's request first goes to the Web server, which then sends the required information to the application server. It then sends the response back to the Web server after taking an appropriate action. The Web server then sends the processed information back to the client. Web servers use different approaches or technology for forwarding or receiving back processed information. Some of the most common approaches are given below.
- CGI (Common Gateway Interface)- Can be written either in JAVA, C, C++, or Perl.
- FastCGI - Improved CGI programming in which each request is not handled as a different process like CGI.
- ASP (Active Server Pages) - A Microsoft Technology
- JSP (Java Server Pages)
- Java Servlets - Sun's Technology
- Java Script (Server Side) - NetScape Technology requires livewire for database connectivity.
First we will examine the Web application architecture without considering the application server as part of the Web application architecture.
All three can be on one machine or spread over the network on different machines as illustrated above.