Proxy Server, The Right Functionality
A proxy server, or proxy for short, is used to allow users within a firewall to access the WWW [LA94]. A proxy server is a special HTTP server that runs either on the firewall machine or on another Internet-based computer within the firewall.
If a client wants to retrieve a document from the WWW server on the Internet within the firewall, it will contact the proxy server. It accepts the request, forwards it to the server outside the firewall, reads the response of the remote server and then sends it back to the requesting client.
The proxy site server acts as both client and server in this type of communication. Compared to the requesting WWW client, it behaves as a WWW server, compared to the remote server as a client.
The client request header is used by the proxy unmodified for its request to the remote server, which causes the WWW client not to lose functionality when using a proxy server.
Because the WWW supports other Internet services, the proxy server is able to act as a gateway to other information servers such as FTP, Gopher, WAIS or news servers. Figure [*] shows that the communication between client and proxy is always handled via the HTTP protocol.
The proxy communicates with the remote server via the respective protocol, in this case via the FTP protocol. In addition, the proxy server must convert the objects it receives from the remote servers into HTTP objects before sending them back to the WWW client.