Professional Microsoft IIS 8

Legacy ISAPI Support

When introduced with IIS 4.0, the Internet Server API (ISAPI) opened doors to a whole new world of server programming. ISAPI provided developers with a means to build on the stable and powerful IIS platform to create web applications with virtually limitless functionality.

With IIS 8.0 and the HttpModule API, ISAPI may well be considered redundant. Although the IIS team has been careful to state that support for ISAPI will not be removed any time soon, there are no strong arguments to compel developers to create new applications using this, now legacy, API.

There are many reasons why the new HttpModule API is superior to ISAPI, including:

• New object-oriented design — The C++ class-based HttpModule API provides a more familiar programming environment with more intuitive objects and structures.
• Improved resource management — New support functions make management of memory and resources more robust and accessible.
• Improved request-state management — With ISAPI, passing state information between various event notifications requires construction of custom objects and complex data structures. The CHttpModule class supports global property definitions, offering a more intuitive mechanism.
• Choice of language — System-level server programming was previously the exclusive domain of native code developers. Now, with support for managed code HTTP modules, this level of control is open to the widest possible developer audience.

With the vast array of third-party and proprietary ...