A server application will internally look as shown in Table 1-2.

Again, the following code is simplified, with various checks on exceptions and other conditions omitted. It exports an implementation of a file classifier service as a FileClassifierImpl object. The full version of the code is given in a later chapter. I don't provide detailed code explanations right now, as this example is just intended to show how the preceding schema translates into actual code.

package nonworking;


public class FileClassifierServer implements DiscoveryListener {
    
    protected LeaseRenewalManager leaseManager = new LeaseRenewalManager();

    public static void main(String argv[]) {
	new FileClassifierServer();

        // keep server running (almost) forever to 
	// - allow time for locator discovery and
	// - keep re-registering the lease
        Thread.currentThread().sleep(Lease.FOREVER);

    }

    public FileClassifierServer() {
	LookupDiscovery discover = null;

        // Prepare for discovery - empty here

        // Discover a lookup service
        // This uses the asynchronous multicast protocol,
        // which calls back into the discovered() method
        discover = new LookupDiscovery(LookupDiscovery.ALL_GROUPS);

        discover.addDiscoveryListener(this);
    }
    
    public void discovered(DiscoveryEvent evt) {
        ServiceRegistrar registrar = evt.getRegistrars()[0];
        // At this point we have discovered a lookup service

        // Create information about a service
	ServiceItem item = new ServiceItem(null,
         				   new FileClassifierImpl(), 
					   null);

        // Export a service
	ServiceRegistration reg = registrar.register(item, Lease.FOREVER);

	// Renew leasing
	leaseManager.renewUntil(reg.getLease(), Lease.FOREVER, this);
    }
} // FileClassifierServer