1. Group Members
Gurpreet Kaur(155)
Himani Kakria
Ritika Sharma
Reetu Rani

2. Contents
O Socket Programming
O Server-Client Communication
O .net Package
O The InetAddress Class & its methods
O getLocalHost()
O getByName(String hostName)
O getAllByName(String hostName)
O getAddress() & getHostName()
O Socket Class
O ServerSocketClass

3. Socket Programming
Networking - process of making two or more computers
communicate.
The important concept associated with networking is the concept of
Sockets and Ports.
SOCKET - A socket is one end-point of a two-way communication link
between two programs running on the network.
Socket classes are used to represent the connection between a client
program and a server program.

4. Server-Client Communication
O Normally, a server has a socket that is bound to a specific port
number.
O On the client-side: The client knows the hostname of the machine
on which the server is running and the port number on which the
server is listening.
O To make a connection request, the client tries to connect with the
server on the server's machine and port.
O If everything goes well, the server accepts the connection.
O On the client side, if the connection is accepted, a socket is
successfully created and the client can use the socket to
communicate with the server.

5. .net Package
O Provide support for networking.
O Contains classes and interfaces to encapsulate the “Socket”
Paradigm.
O The java.net package provides two classes—
O Socket - implement the client side of the connection
O Ser verSocket- implement the server side of the connection

6. The InetAddress Class
O It converts the domain name of Internet address into an
Object. This class represents an Internet Protocol (IP)
address.
O Doesn’t have Constructors.
O Three static methods are used to create instances.
O getLocalHost()
O getByName(String hostName)
O getAllByName(String hostName)
O All these methods throw UnknownHostException if the
method cannot resolve the host name.

7. getLocalHost()
import java.net.*;
class obtainIP
{
public static void main(String args []) throws UnknownHostException
{
InetAddress adr;
adr=InetAddress.getLocalHost();
System.out.println("nInfo about Machine: " + adr);
}
}

8. getByName(String hostName)
import java.io.*;
import java.net.*;
class obtainIP2
{ public static void main(String args []) throws IOException
{ InetAddress adr;
String host;
DataInputStream input=new DataInputStream(System.in);
System.out.println("Enter the Machine's Hostname");
host=input.readLine();
try {
adr=InetAddress.getByName(host);
System.out.println("nInfo about Host "" + host + "" is:- " + adr);
}
catch( UnknownHostException e) {
System.out.println("No such host exist"); }
}
}

9. Output

10. getAllByName(String hostName)
import java.io.*; try {
import java.net.*; adr=InetAddress.getAllByName(host);
class obtainIP3 for(int i=0;i<adr.length;i++)
{ {
public static void main(String args [ ]) j++;
throws IOException System.out.println(j +"t" + adr[i]);
{ }
InetAddress adr[]; int j=0; }
String host;
DataInputStream input=new catch( UnknownHostException e)
DataInputStream(System.in); {
System.out.println("No such host exist");
System.out.println("Enter host "); }
host=input.readLine(); }
}

11. Output

12. getAddress() & getHostName()
import java.net.*;
class obtainIP4
{ public static void main(String args []) throws UnknownHostException
{
String msg;
byte num[];
InetAddress adr;
adr=InetAddress.getLocalHost();
num=adr.getAddress();
msg=adr.getHostName();
System.out.println("LocalHost= " + adr);
for(int i=0;i<num.length;i++)
{
msg +=(num[i] & 255) + ".";
System.out.println("Num= " + msg);
}
}
}

13. Output

14. Socket Class
O The Socket class ,basically used to create client sockets, is
designed to connect to server socket and initiate protocol
exchanges.
O When Socket object is created, it implicitly establishes the
connection b/w client and server.
O Socket defines the constructors to create client sockets.
Constructors:-
Socket(String hostname, int port);
Socket(InetAdrress ipaddr, int port);

15. Socket Class Methods
Methods:-
1)InputStream getInputStream();
1)OutputStream getOutputStream();
1)void close();

16. ServerSocket Class
The ServerSocket class, basically used to create server sockets,
is designed to be a listener, which waits for client to connect
before doing anything.
Constructors:-
ServerSocket ( int port );
ServerSocket ( int port, int queueLength);
Method:-
Socket accept();
accept() is a blocking call that waits for a client to initiate
communication and returns a normal Socket, that is used for
communication with the client.