Visual C++ 6 Unleashed

Visual C++ 6 Unleashed

By MICKEY WILLIAMS and David Bennett

Summary

In this chapter, you learned how you can use the Internet Server API (ISAPI) to create both Internet Server Extension Applications (ISAs) and ISAPI filters, which you can use to add functionality to ISAPI-compliant HTTP servers, such as that supplied with Microsoft's Internet Information Server.

You looked at creating an ISA extension DLL, which can process requests made directly by a client, and the entry points that are exported by an ISA DLL, including GetExtensionVersion(), TerminateExtension(), and HttpExtensionProc()—the real workhorse function of an ISA.

You also took a look at the information provided to your ISA by the server in the EXTENSION_CONTROL_BLOCK structure, which also provides pointers to utility functions such as GetServerVariable(), WriteClient(), ReadClient(), and ServerSupportFunction().

Next, you saw how to create an ISAPI filter DLL, which you can use to perform special processing for many different events in the process of handling an HTTP request. You learned how the GetFilterVersion() and HttpFilterProc() functions can be implemented and exported for use by the Web server, as well as the HTTP_FILTER_CONTEXT structure, which is used to pass information about a request and to provide utility functions for your filter, including GetServerVariable(), AddResponseHeaders(), WriteClient(), AllocMem(), and ServerSupportFunction().

In addition, you took a look at the MFCs that are provided to encapsulate ISAPI, including the CHttpServer, CHttpServerContext, and CHtmlStream classes, which are used to create ISAs using parse maps, as well as the CHttpFilter and CHttpFilterContext classes, which can be used to implement ISAPI filters. You also saw how to use the ISAPI Extension Wizard to create a framework for applications using these MFCs.

Share ThisShare This

Informit Network