FastCGI

FastCGI's main aim is to reduce the overhead related to interfacing between web server and CGI programs, allowing a server to handle more web page requests per unit of time. Common Gateway Interface (CGI) is an interface specification allowing external applications to interact with web servers. CGI applications run in separate processes, which are created at the start of each request and torn down at the end. This "one new process per request" model makes CGI programs very simple to implement, but limits efficiency and scalability. At high loads, the operating system overhead for process creation and destruction becomes significant. Also, the CGI process model limits resource reuse methods, such as reusing database connections, in-memory caching, etc. To address the scalability shortcomings of CGI, Open Market developed FastCGI and first introduced it in their webserver product in the mid-1990s. Open Market originally developed FastCGI in part as a competitive response to Netscape's proprietary, in-process application programming interfaces (APIs) (Netscape Server Application Programming Interface (NSAPI)) for developing Web applications. While developed first by Open Market, FastCGI was then implemented by several other webserver makers.