Internet Server Application Programming Interface

World-Wide Web (ISAPI) Microsoft's programming interface

between applications and their Internet Server. Active

Servers created with ISAPI extensions can be complete

in-process applications themselves, or can "connect" to other

services. ISAPI is used for the same sort of functions as

CGI but uses Microsoft Windows dynamic link libraries

(DLL) for greater efficiency. The server loads the DLL the

first time a request is received and the DLL then stays in

memory, ready to service other requests until the server

decides it is no longer needed. This minimises the overhead

associated with executing such applications many times.

An HTTP server can unload ISAPI application DLLs to free

memory or preload them to speed up the first access.

Applications can also be enhanced by ISAPI filters

(1997-01-06)