Chapter 22.4, Problem 8SC

Program Plan Intro

Socket Programming:

• Sockets include the method of communication using TCP between two computers.
• A client program generates a socket on its end of the communication and tries to connect that socket to a server.
• When the connection is made, the server creates a socket object on its end of the communication.
• The “java.net.Socket” class denotes a socket, and the “java.net.ServerSocket” class offers a mechanism for the server program to listen for clients and create connections with them.
• The steps given below occurs when establishing a connection between two computers with the help of sockets.
  • A “ServerSocket” object is instantiated by the server, denoting which port number communication should occur.
  • The method “accept()” of the “ServerSocket” class is invoked by the server. This method awaits until a client on the provided port connects to the server.
  • A client instantiates a “Socket” object after the server is waiting, specifying the server name and port number to connect to.
  • The “Socket” class constructor tries to connect the client to the specified server and to the number of the port. If connection is created, the client will now have a Socket object which can communicate with the server.
  • The method “accept()” on the server side returns a reference to a new socket on the server which is connected to the socket of the client.
• After establishing the connections, communication can occur using I/O streams.

Justification:

• “No”, the user cannot read data from a server socket.
• A server socket just waits for a connection and when a client has connected, it produces a regular Socket object.
• One can use that socket object to read the data that the client sends.
• Therefore, socket objects are used for read the data sent by the clients.