Request and response must know

Desktop applications   There's no need for the Internet
    C/S Pattern
    Client client ,Server The server     QQ  1. Download installation package 2. Install to this machine 3. Network sending and receiving messages
     benefits
    1. The effect is cool  2. Fast response  
    3. Separate the ends The system is stable  4. If you don't need a network LAN fly Q High safety
     Not good.
    1. The program installed on the computer is not safe Misoperation
    2. Version update   Poor maintenance
    3. The development cycle is relatively long High coupling degree

    B/S Pattern
    Browser browser ,Server The server
     The browser is equivalent to our previous client      All components are not on the client   Write a unified specification for browsers
    1.socket
    2.I/O
    3.String     agreement
    4. Threads
    5. aggregate   object-oriented
    

     request ---- Respond to
                 There's a server (Tomcat)
                 Put our written resources (HTML JSP Controller Service DAO domain) Deployed in the server
                 Start the server , The server will run with resources ( Waiting for someone to visit , Help you schedule )

Browser open , Input URL
You may need to click to operate in the future
Send a request ---->             Every time a browser is connected after the server is started , Will open a thread object
                1. Receive request information     
                2. analysis     
                     All the information carried in the request is wrapped into an object request
                     In order to receive the results after execution , Created an empty object response
                3. Look for resources
                     The server will refer to a " Instructions "  web The configuration file
                4. Resource doing
                     Value Looking for business Response to response.write("");