Socket Programming(TCP & UDP) Sanjay Chakraborty

Transcription

1 Socket Programming(TCP & UDP) Sanjay Chakraborty

2 Computer network programming involves writing computer programs that enable processes to communicate with each other across a computer network. The endpoint in an interprocess communication is called a socket, or a network socket for disambiguation. Since most communication between computers is based on the Internet Protocol, an almost equivalent term is Internet socket. The data transmission between two sockets is organised by communications protocols, usually implemented in the operating system of the participating computers. Application programs write to and read from these sockets. Therefore, network programming is essentially socket programming.

3 The TCP and UDP protocols use ports to map incoming data to a particular process running on a computer. Port is represented by a positive (16-bit) integer value. Some ports have been reserved to support common/well known services:

4 ftp 21/tcp telnet 23/tcp smtp 25/tcp login 513/tcp http 80/tcp,udp https 443/tcp,udp

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7 To get the local IP address of your local machine InetAddress class and getlocalhost() It throws UnknownHostException static InetAddress getbyname(string hostname) throws UnknownHostException The getlocalhost( ) method simply returns the InetAddress object that represents the local host. The getbyname( ) method returns an InetAddress for a host name passed to it. If these methods are unable to resolve the host name, they throw an UnknownHostException..

8 Chat server using TCP Client and TCP Server TCP Client: Import net, util and io package. Class TCPclient { Socket cs=new Socket( localhost,8001); InputStream is=cs.getinputstream(); DataInputStream dis=new DataInputStream(is); OutputStream os=cs.getoutputstream(); DataOutputStream dos=new DataOutputStream(os); InputStreamReader isr=new InputStreamReader(System.in); BufferedReader br=new BufferedReader(isr); While(true) { System.out.println( send: ); dos.writeutf(br.readline()); System.out.println( Received +dis.readutf(dis)); } }

9 TCP Server: Import net, util and io package; Class TCPserver { ServerSocket ss=new ServerSocket(8001); //creating a server socket Socket cs=ss.accept(); //wait for connection InputStream is=cs.getinputstream(); DataInputStream dis=new DataInputStream(is); OutputStream os=cs.getoutputstream(); DataOutputStream dos=new DataOutputStream(os); InputStreamReader isr=new InputStreamReader(System.in); BufferedReader br=new BufferedReader(isr); While(true) { System.out.println( Message from client: +dis.readutf(dis)); System.out.println( send: ); dos.writeutf(br.readline()); }}

10 readutf() = It is a method of DataInputStream class which accepts the data coming from another machine. JDBC JDBC is needed to perform the following tasks, i. Store and update the data in a database. ii. Retrieve the data stored in a database and present it in a proper format to users. Sun Microsystems has included jdbc API as a part of jdk to enable java application to communicate with a database.

11 User data entry form JDBC API User Database Data Source name (DSN) Creation: Control panel Administrative Tools Data Sources (odbc) System DSN Microsoft access driver Click Add Give data source name and click select button to select database. Choose only (*.mdb,.accdb)

12 import java.sql.*; class sqlexam { public static void main(string args[]) { String str,s1; System.out.println("This is an example of jdbc"); try{ Class.forName("sun.jdbc.odbc.JdbcOdbcDriver"); Connection con=drivermanager.getconnection("jdbc:odbc:dsn1","",""); PreparedStatement ps=con.preparestatement("select *from sample"); ResultSet rs=ps.executequery(); while(rs.next()) { str=rs.getstring(1); System.out.println("The name is:"+str); int s=rs.getint(2); System.out.println("The rollno.is:"+s); s1=rs.getstring(3); System.out.println("The desig is:"+s1); } con.close(); } catch(exception e) {} } }

13 import java.sql.*; class sqlexam{ public static void main(string args[]) { String str,s1; System.out.println("This is an example of jdbc"); try { Class.forName("sun.jdbc.odbc.JdbcOdbcDriver"); Connection con=drivermanager.getconnection("jdbc:odbc:dsn1","",""); //PreparedStatement ps=con.preparestatement("insert into sample values('rakesh',10,'speaker')"); PreparedStatement ps=con.preparestatement("delete *from sample where rollno=10"); int i=ps.executeupdate(); System.out.println("record deleted"+i); con.close(); } catch(exception e) {} } }

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