Structure of a FastCGI Application

A typical FastCGI application has the following code structure:

Initialization code

Start of response loop
		body of response loop
End of response loop

The initialization code is run only once at the time of the application initialization. Initialization code usually performs time-consuming operations such as opening databases or calculating values for tables or bitmaps. The main task of converting a CGI program into a FastCGI program is to separate the initialization code from the code that needs to run for each request.

The response loop runs continuously, waiting for client requests to arrive. The loop starts with a call to FCGI_Accept, a routine in the FastCGI library. The FCGI_Accept routine blocks program execution until a client requests the FastCGI application. When a client request comes in, FCGI_Accept unblocks, runs one iteration of the response loop body, and then blocks again waiting for another client request. The loop terminates only when a System Administrator or the Web Server kills the FastCGI application.