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Requests and Responses flow in server

In this section, we will understand detailed specification of user’s request and response. We will study about Request and response handling by server.


How, user send request to server?
  • User opens browser.
  • He/she types address of server side resource (like http://localhost:8080/WebApp1/hello in over example of chapter one) in address bar.
  • Browser build request packet and place the address from the address bar in the header of request (e.g. In this example request packet contains machine address localhost, port number 8080 and resource uri WebApp1/hello). Along with address field request packet consists of protocol field i.e. http and other required fields.
  • Packet is delivered to network from user’s machine.
  • This packet is treated by routers and forwarded until it reaches to final destination.
  • Finally packet is reached to the server machine (or host) having the same address as packet’s address (Note: address may be IP address of domain name like yahoo.com).
  • On the server side, network data receiving process checks the port number of the received packet (i.e. 8080).
  • Data receiving process deliver it to the process or program that is listing on this port number (i.e 8080).
  • Server that is listening on the port 8080 has numbers of web applications running inside it. Then Server checks the resource address or path matching to the resource address came with request packet (i.e. /WebApp1/hello).
  • If there server finds the resource, it process the request of client.
    • Server searches the resource in web application in with the name or url pattern of resource.
    • If resource if static page, server returns it to client.
    • If resource is dynamic page(e.g. jsp) or servlet program, resource is proceed by the server and the output is sent to client.
  • After processing request, server creates response packet and places the address of client machine with the port number of client process which sent this request.
  • Then response is delivered to client through network.
  • And use sees the response come from server.
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