Developing ISAPI Extensions

You can reduce server overhead and Web access time if you write an ISAPI extension, a run-time DLL used by IIS. You can load an extensions in the same process as IIS for best performance, or into an isolated process to guard against corruption of the IIS process.

This section contains:

• Extension Request Processing, which provides a high level overview of the order in which processing events occur.
• Using Callback Functions, which describes how the extension communicates processing results to IIS.
• Asynchronous I/O Processing, which illustrates the order of processing events when a function performs asynchronously.
• Extension Security Issues, which discusses how security context is passed to an ISAPI extension.
• Basic Extension Framework, which outlines the minimum requirements for an ISAPI extension.
• Sending a Header, which demonstrates how to use the ServerSupportFunction as a callback function.
• Reading and Writing Asynchronously, which demonstrates how to use ReadClient for asynchronous processing.
• Shutting Down an Extension, which demonstrates how to use the TerminateExtension function to unload an extension from memory.
• Converting Existing CGI Scripts to ISAPI Extensions, which provides some of the development steps that are required to convert an existing CGI application to an extension.
• Important Notes for Extension Developers, which expands on some general issues regarding developing extensions.