An ISAPI server extension is a DLL that can be loaded and called by an HTTP server.
ASP.NET就是一种ISAPI Extension。Http Handler类似扩展。
An ISAPI filter is a DLL that runs on an ISAPI-enabled HTTP server to filter data traveling to and from the server.
ISAPI filter提供了查看进入IIS的每一个请求的能力,并能修改请求的内容或者改变功能型的行为,例如认证等Http Module类似过滤器。
待续。。。