FastCGI (http://www.fastcgi.com) is an open extension to CGI (Common Gateway Interface), which is a standard for interfacing external applications with web servers. Like CGI, FastCGI applications run in separate, isolated processes. Some of the FastCGI's advantages are as follows:
Performance - FastCGI processes are persistent; they are reused to handle multiple requests. This solves the CGI performance problem of creating new processes for each request.
Support for distributed computing - FastCGI provides the ability to run applications remotely, which is useful for distributing load.
Process isolation - FastCGI application does not crash or corrupt the core server or other applications.
The FastCGI plug-in allows the Sun Java System Web Server to safely work with third-party dynamic content generation technologies such as PHP, Perl and Python in a scalable way.
The FastCGI plug-in implements the client side of the FastCGI protocol. This protocol allows producers of dynamic content (and content engines) to implement a common and scalable API that can be utilized by many web servers.