socket creation doubt ?

[Anand Divakaran]

HI,
I am trying to write a simple client server program, both the client and server program resides on the same local machine .
while creating a socket i dont know which port to mention
syntax
public Socket(InetAddress,int port)

How can i know which ports i can use .
i am working on my personal system so there is no question of admin problem
or restrictions

[Ernest Friedman-Hill]

You can use any port that's not currently in use. Most official services use ports below number 1024, so it's best to steer clear of those (and on UNIX, you can't use those without special privileges.) Pick a number above 2000 and if it works, then it's OK! Note that the important thing is that both client and server use the same number.

[Anand Divakaran]

After creating a socket, can it be used to send and receive data .
or is it each time i use it for sending or receiving i have to close the socket and create a new one?

[Ulf Dittmer]

Sockets can be used for two-way communication (sending and receiving), and they do not need to be closed every time they send or receive something.

[Nicholas Jordan]

package demo;
 
import java.util.Random;//
import java.net.*;//
 
/* USE OF THIS CODE CONSTITUTES DISCUSSION OF OPINION IN A TECHNICAL FORUM
 * NO SUITABILITY FOR ANY USE IS IMPLIED BY READING THE OPINION PROVIDED
 *
 * (  sound pretty impressive ?  )
 *
 * Simple client/server Socket selection program: ubb = get_topic & f=8 & t=002898
 * Select a port to invoke the public Socket(InetAddress,int port) with.
 * The Dynamic and/or Private Ports are those from 49152 through 65535
 * Source:  <a href="http://www.iana.org/assignments/port-numbers" target="_blank" rel="nofollow">http://www.iana.org/assignments/port-numbers</a>
 * The port numbers are divided into three ranges: the Well Known Ports,
 * the Registered Ports, and the Dynamic and/or Private Ports.
 */
 
 public class PortSelector extends Socket
 {
     int port;//
     InetAddress nannaBanna;//
     private Socket sockitToEm;//
     PortSelector(InetAddress incoming, int suggested) throws java.io.IOException //
     {
         if((suggested >= 49152) && (suggested <= 65535)) port = suggested;//
         if(incoming != null) nannaBanna = incoming;//
         Random candidatePort = new Random();//
         int bias = (65535 - 46152);// per javadoc
         if(port == 0){while(((port = candidatePort.nextInt(bias) +  49152) <= 49152) && (port > 65535))continue;}//
         sockitToEm = new Socket( nannaBanna , port);// really should throw if(nannaBanna == null)
     }
     public Socket getSocket(){return sockitToEm;}
 }

http://www.docdubya.com/belvedere/statement/browser.html

( ... an article written by Anish Shaikh ... )



[ Code here used by Nicholas Jordan in his project, thank you poster ! ]

[ Message edited 4:42 PM 9/21/2007: bias == (65535 - 46152) ]
[ September 23, 2007: Message edited by: Nicholas Jordan ]