Chapter 22, Problem 5RE

Program Plan Intro

Socket:

• Sockets include the method of communication using TCP between two computers.
• A socket is an object that encapsulates a TCP/IP connection.
• 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.

Difference between a Socket object and a ServerSocket object:

Socket object	ServerSocket object
Socket object is the object of class “java.net.Socket”.	ServerSocket object is the object of class “java.net.ServerSocket”.
Socket object is created by client application.	ServerSocket object is created by server application.
Socket object is used for establishing connection to the server for services.	“ServerSocket” object is used for listening to the client connections.