5.2 communication data forwarding procedure: proxy, gateway, tunnel
5.2.1 Agent
The basic behavior is to accept the proxy server forwards the request to the other server sent by the client.
The reason for using a proxy server: the use of caching technology to reduce network bandwidth traffic, access control within the organization for a particular site.
Acting in two reference classifications. One is whether to use the cache, the other is whether it will modify the message.
Caching proxy
Response proxy forwarding, caching proxy will advance copy of the resource stored on the proxy server. When the agent receives a request for the same resource again, the resources can not be acquired from a source server, the previously cached resource returned as the response.
Transparent Proxy
When forwarding or responding agency does not do any type of message processing.
5.2.2 Gateway
5.2.3 Tunnel
Required to establish a line of communication with other servers, then using SSL encryption to communicate. The purpose of the tunnel is to ensure that the client can communicate securely with the server.
The tunnel itself will not go parsing HTTP request.
