HTTP response

Request and response messages through connections

Data is exchanged through a sequence of request–response messages which are exchanged by a session layer transport connection. An HTTP client initially tries to establish a connection, real or virtual, with a server. An HTTP server listening on the port accepts the connection and then waits for a client's request message. The client sends its HTTP request message. Upon receiving the request the server sends back an HTTP response message, which includes header(s) plus a body if it is required. The body of this response message is typically the requested resource, although an error message or other information may also be returned. At any time and for many reasons, either the client or server can close the connection. Closing a connection is usually advertised by one or more HTTP headers in the last request or response.