Behalf

Behalf - A server that sits between a client application, such as a Web browser, and a real server. In other words, a proxy server.

It intercepts all requests to the real server to see if it can fulfill the requests itself. If not, it forwards the request to the real server.

Proxy servers have three main purposes: ￭ Improve Performance: Proxy servers can dramatically improve performance for groups of users. This is because it saves the results of all requests for a certain amount of time. Consider the case where both user X and user Y access the World Wide Web through a proxy server. First user X requests a certain Web page, which we'll call Page 1. Sometime later, user Y requests the same page. Instead of forwarding the request to the Web server where Page 1 resides, which can be a time-consuming operation, the proxy server simply returns the Page 1 that it already fetched for user X. Since the proxy server is often on the same network as the user, this is a much faster operation. Real proxy servers support hundreds or thousands of users. The major online services such as Compuserve and America Online, for example, employ an array of proxy servers. ￭ Minimizes ISP bandwidth use. ￭ Filter Requests: Proxy servers can also be used to filter requests. For example, a company might use a proxy server to prevent its employees from accessing a specific set of Web sites. Note: Behalf must not be used as a firewall, it's a filter. People using a proxy server should feel as if they are getting responses directly from remote servers.

Clients without Domain Name Services (DNS) can still use the Web. The proxy IP address is the only information they need. Organizations using private network address spaces such as the class A net 10.*.*.* can still use the Internet as long as the proxy is visible to both the private internal net and the Internet.

Proxy servers can allow or deny internet requests according to the protocol of the requests. For instance a proxy server can allow calls to FTP servers while denying calls to HTTP servers.