A communication protocol and by extension an ApacheModule?
which allow persistent CGIs.
Quite interesting when to reduce interpretation overhead, database connection setting, etc...
It can be used with at least C, PerL?, [TCL], Java and Python (I have only tried C and PerL?)
For CGIs written in PerL?, you use a modified version of the CGI module and just loop waiting for a request.
Exists as a DebianPackage? (libapache-mod-fastcgi + libfcgi-perl).
Used (among others) by the [Sympa] mailing-list manager for its web interface.
More information there:
[fastcgi.com] [apachemodule doc]