Developing a Jini Client by Gopalan Suresh Raj

This simple Jini client Queries the Jini Service for it's current time in milliseconds by invoking it's getTime() method. It then computes the time taken for the message to reach it and prints it out in milliseconds.

MyClient.java

import net.jini.core.entry.*;
import net.jini.core.lookup.*;
import net.jini.core.discovery.*;
import net.jini.lookup.*;
import net.jini.lookup.entry.*;
import net.jini.discovery.*;

import java.rmi.*;
/***************************************************************************

MyClient -- The Jini Client Class

***************************************************************************/

class MyClient {
public static void main (String[] args) {
int iPort;
String sHost;
Entry[] aeAttributes;
LookupLocator lookup;
ServiceID id;
ServiceRegistrar registrar;
ServiceTemplate template;
MyServerInterface myServerInterface;

try {
   /*
   Setting the security manager to allow the RMI class loader
   to go to the codebase for classes that are not available
   locally.
   ========================================================== */
   System.setSecurityManager (new RMISecurityManager ());

   /*
   Find the Jini lookup service (reggie) and print its location.
   ============================================================= */
   lookup = new LookupLocator ("jini://localhost");
   sHost = lookup.getHost ();
   iPort = lookup.getPort ();
   System.out.println ();
   System.out.println ("client: LookupLocator = " + lookup);
   System.out.println ("client: LookupLocator.host = " + sHost);
   System.out.println ("client: LookupLocator.port = " + iPort);

   /*
   Get the lookup service's ServiceRegistrar (the class by which
   interaction with the lookup service is possible).
   ============================================================= */
   registrar = lookup.getRegistrar ();
   id = registrar.getServiceID ();
   System.out.println ("client: ServiceRegistrar = " + registrar);
   System.out.println ("client: ServiceID = " + id);

   /*
   Perform a search on the lookup server to find the service
   that has the name attribute of "MyServer". The lookup
   service returns an interface object to the service.
   ========================================================= */
   aeAttributes = new Entry[1];
   aeAttributes[0] = new Name ("MyServer");
   template = new ServiceTemplate (null, null, aeAttributes);
   myServerInterface = (MyServerInterface) registrar.lookup (template);
   System.out.println ("client: ServiceTemplate = " + template);
   System.out.println ("client: Service object = " + myServerInterface);

   /*
   If the correct object was returned, call one of its methods.
   ============================================================ */
   if (myServerInterface instanceof MyServerInterface) {
    long startTime = myServerInterface.getTime();
    System.out.println ("client: Time at server is " + startTime);
    long stopTime = System.currentTimeMillis();
    System.out.println ("client: Time at client is " + stopTime);
    float difference= stopTime-startTime;
    System.out.println ("client: Time for message to traverse the net is --->"
                        + difference + " msecs<---");
   }
} catch (Exception e) { System.out.println ("client: MyClient.main() exception: " + e); }
}
}