Request/response

In describing the nature of the client-server relationship, we've also touched on the nature of the HTTP request/response protocol. This protocol, as a way of serving up information, is fairly intuitive to understand. When a client makes a request of a server (the request part of request/response), the server, assuming it meets the specifications of the protocol, is expected to respond with meaningful information about the success or failure of that request, as well as by providing the specific data initially requested.

Sometimes, the complete process of requesting information and receiving a meaningful response requires several intermediary round-trips between the client and server to establish initial connections, determine the ability of the server to service the request, and then submit the information necessary to initiate the request. This entire process, however, will be considered a single request/response session from the perspective of application-layer software. This leads us nicely onto the subject of just how those sessions are initially established in the first place.