JAVA NETWORKING TCP/IP CLIENT SOCKETS CONTENTS

JAVA NETWORKING TCP/IP CLIENT SOCKETS CONTENTS

TCP/IP CLIENT SOCKETS

Transmission control protocol(TCP) is a connection-oriented, reliable   protocol which supports the transfer of data in continuous streams.

The addressing scheme used in TCP is makes use of ports.

This type of communication is called as socket programming.

             

                  Port number           Service

               21                              FTP

               23                             Telnet

               25                             SMTP

               80                             HTTP

              110                            POP3

User level processes or services generally use portnumbers>=1024

A socket is bound to a port number so that the TCP/UDP from transport layer can identify the corresponding application at destination.

TCP/IP CLIENT SOCKETS

Server is a device which has resources and from which the services can be obtained.

    

   Client is a device which wants to get service from particular server.

	Client	Server
1	Creates TCP socket	Creates TCP socket
2	Client initiates the communication. Communicate	Creates another socket for listening client. Accept message from client and repeatedly communicate.
3	Close the connection	Close the connection

TCP/IP CLIENT SOCKETS

These steps can be illustrated by following figure:

There are two constructors used to create client socket.

Constructor	Meaning
Socket(String hostname , int port)	Creates a socket connecting the local host to the named host and port.
Socket(InetAddress  ipAddress , int port)	Creates a socket using a pre-existing InetAddress object and a port.

The methods used for examining the socket are.

InetAddress getInetAddress()	Returns the InetAddress associated with the Socket object.
Int getPort()	Returns the remote port to which this Socket object is connected.
Int get.ocalPort()	Returns the local port to which this