1. Web Design & Development 1 Lec - 21 Umair Javed

2. Web Design & Development 2 Socket Programming

3. Umair Javed©2005 JDBC3 Request – Response Model animation

4. Umair Javed©2005 JDBC4 Socket A socket is one endpoint of a two-way communication link between two programs running on the network. A socket is a bi-directional communication channel between hosts (a computer on a network can be termed as a host). A socket is bound to a port number

5. Umair Javed©2005 JDBC5 Socket’s Dynamics A Socket is an abstraction of the network similar to the way a file is an abstraction of your hard drive.  You store and retrieve data through files from hard drive without knowing the actual dynamics of the hard drive.  Similarly you send and receive data to and from network through socket without actually going into underlying mechanics.

6. Umair Javed©2005 JDBC6 Sending/Receving Messages using Socket You read from or write data to a file, using streams. Similarly to read from or write data to a socket, you use streams.

7. Umair Javed©2005 JDBC7 Transport address to which processes can listen for connection requests Local to host: 64K TCP & 64K UDP ports Well-known ports –Below 1024 –Standard services –Only supervisor privileged enough to access What is a Port? Examples  FTP: 21  HTTP: 80  TELNET: 23

8. Umair Javed©2005 JDBC8 Request – Response Model host:port Clients make “calls” to that port # Server listens on a port # host:port

9. Umair Javed©2005 JDBC9 How Client & Server communicate animation

10. Umair Javed©2005 JDBC10 Steps – To Make a Simple Client 1.Import required Package 2.Connect / Open a Socket with Server 3.Get I/O Streams of Socket 4.Send / Receive Message 5.Close Socket

11. Umair Javed©2005 JDBC11 Steps – To Make a Simple Client 1.Import required Package import java.net.*; import java.io.*; 2.Connect / Open a Socket with Server Socket s = new Socket(“sAdd”, sPort);

12. Umair Javed©2005 JDBC12 Steps – To Make a Simple Client 3.Get I/O Streams of Socket InputStream is = s.getInputStream(); InputStreamReader isr= new InputStreamReader(is); BufferedReader br = new BufferedReader(isr); OutputStream os = s.getOutputStream(); PrintWriter pw = new PrintWriter(os, true); Show code here FileReader fr = new FileRes.. BufferedReader br = new Bu..

13. Umair Javed©2005 JDBC13 animation

14. Umair Javed©2005 JDBC14 Steps – To Make a Simple Client 4.Send / Receive Message pw.println(“hello world”); String recMsg = br.readLine(); 5.Close Socket s.close();

15. Umair Javed©2005 JDBC15 Steps – To Make a Simple Server 1.Import required Package 2.Create a Server Socket 3.Wait for Incoming Connections 4.Get I/O Streams of communication Socket 5.Send / Receive Message 6.Close Socket

16. Umair Javed©2005 JDBC16 Steps – To Make a Simple Server 1.Import required Package import java.net.*; import java.io.*; 2.Create a Server Socket ServerSocket ss = new ServerSocket(portNo);

17. Umair Javed©2005 JDBC17 Steps – To Make a Simple Server 3.Wait for Incoming Connection –When connection established, communication socket is returned Socket s = ss.accept();

18. Umair Javed©2005 JDBC18 Steps – To Make a Simple Server 4.Get I/O Streams of Socket InputStream is = s.getInputStream(); InputStreamReader isr= new InputStreamReader(is); BufferedReader br = new BufferedReader(isr); OutputStream os = s.getOutputStream(); PrintWriter pw = new PrintWriter(os, true);

19. Umair Javed©2005 JDBC19 Steps – To Make a Simple Server 5.Send / Receive Message pw.println(“hello world”); String recMsg = br.readLine(); 6.Close Socket s.close();

20. Umair Javed©2005 JDBC20 aniamtion

21. Web Design & Development 21 Example Code Echo Server

22. Web Design & Development 22 Example Code Echo Client