Cache Proxy
A Windows Media Server can stream content to a client from a local cache or proxy it from an upstream server. If a cache proxy plug-in has been enabled, the server queries it to determine what action the server must take in response to a client's request for content. That is, the plug-in sets the appropriate cache proxy policy, and the server carries it out. For example, if the requested content is cached locally, the plug-in can direct the server to stream it from cache. If the content does not exist locally or exists but has expired, the plug-in can direct the server to both proxy it from the origin and download it to local storage. The actual implementation of the plug-in depends on you. In general, the plug-in can direct the server to
Disconnect the client.
Redirect the client to an alternate URL.
Redirect the client to an alternate proxy.
Play the requested content as a broadcast.
Play the requested content as an on-demand stream.
Windows Media Services does not include a cache proxy plug-in, but you can create your own. For more information, see Creating Cache Proxy Plug-ins.