Server code

The implementation of the naming service can be a CosNaming service in the Common Object Request Broker Architecture (CORBA) environment. A CosNaming service is a collection of naming services, and implemented as a set of interfaces defined by CORBA. Alternatively, the naming service can be implemented using a Remote Method Invocation (RMI) registry for an RMI(JRMP) application. You can use JNDI in CORBA and in RMI cases. The effect is to make the server implementation independent of the naming service that is used. For example, you could use the following code to obtain a naming service and bind an object reference in it:

Context ctx = new InitialContext(...); 	// get hold of the initial context 
ctx.bind("sample", sampleReference);		// bind the reference to the name "sample"	 	
Object obj = ctx.lookup("sample");		// obtain the reference

To tell the application which naming implementation is in use, you must set one of the following Java properties:

java.naming.factory.initial

Defined also as javax.naming.Context.INITIAL_CONTEXT_FACTORY, this property specifies the class name of the initial context factory for the naming service provider. For RMI registry, the class name is com.sun.jndi.rmi.registry.RegistryContextFactory. For the CosNaming Service, the class name is com.sun.jndi.cosnaming.CNCtxFactory.

java.naming.provider.url

This property configures the root naming context, the Object Request Broker (ORB), or both. It is used when the naming service is stored in a different host, and it can take several URI schemes:

• rmi
• corbaname
• corbaloc
• IOR
• iiop
• iiopname

For example:

rmi://[<host>[:<port>]][/<initial_context>] for RMI registry    
iiop://[<host>[:<port>]][/<cosnaming_name>] for COSNaming

To get the previous properties in the environment, you could code:

Hashtable env = new Hashtable(); 	
Env.put(Context.INITIAL_CONTEXT_FACTORY, 		
       "com.sun.jndi.cosnaming.CNCtxFactory");

and pass the hash table as an argument to the constructor of InitialContext.

With CORBA (Java IDL), however, you must do some extra work because you have to create an ORB. The ORB has to make the servant reference available for remote calls. This mechanism is typically controlled by the object adapter of the ORB.

public class Server {
	public static void main (String args []) {
		try {
			ORB orb = ORB.init(args, null);
			
			// Get reference to the root poa & activate the POAManager 
			POA poa = (POA)orb.resolve_initial_references("RootPOA"); 
			poa.the_POAManager().activate(); 
			
			// Create a servant and register with the ORB
			SampleImpl sample = new SampleImpl();			
			sample.setORB(orb); 

			// TIE model ONLY
			// create a tie, with servant being the delegate and
			// obtain the reference ref for the tie
			SamplePOATie tie = new SamplePOATie(sample, poa); 
			Sample ref = tie._this(orb);

			// Inheritance model ONLY
			// get object reference from the servant 
			org.omg.CORBA.Object ref = poa.servant_to_reference(sample);
      Sample ref = SampleHelper.narrow(ref);

			// bind the object reference ref to the naming service using JNDI
	   		..........(see previous code) .....
			orb.run();
		}
		catch(Exception e) {}
	}
}

For RMI-IIOP:

public class Server {
	public static void main (String args []) {
		try {
			ORB orb = ORB.init(args, null);
			
			// Get reference to the root poa & activate the POAManager 
			POA poa = (POA)orb.resolve_initial_references("RootPOA"); 
			poa.the_POAManager().activate();

			// Create servant and its tie
			SampleImpl sample = new SampleImpl();
			_SampleImpl_Tie tie = (_SampleImpl_Tie)Util.getTie(sample); 
			
			// get an usable object reference 
			org.omg.CORBA.Object ref = poa.servant_to_reference((Servant)tie);

			// bind the object reference ref to the naming service using JNDI
	   		..........(see previous code) .....
		}
		catch(Exception e) {}
	}
}

RMI Client example:

public class SampleClient { 	 
  public static void main(String [] args) {  	    
    try{ 			 		
      Sample sampleref
      //Look-up the naming service using JNDI and get the reference 			
            ......... 		
      // Invoke method   		
      System.out.println(sampleRef.message()); 	    
    } 	    
    catch(Exception e) {} 	  
  } 	
}  

CORBA Client example:

public class SampleClient {
	public static void main (String [] args) {
		try {
			ORB orb = ORB.init(args, null);
			// Look up the naming service using JNDI
			......
			// Narrowing the reference to the correct class
			Sample sampleRef = SampleHelper.narrow(o);
			// Method Invocation
			System.out.println(sampleRef.message());
		}
		catch(Exception e) {}
	}
}

RMI-IIOP Client example:

public class SampleClient {
	public static void main (String [] args) {
		try{
			ORB orb = ORB.init(args, null);
			// Retrieving reference from naming service
			........
			// Narrowing the reference to the correct class
			Sample sampleRef = (Sample)PortableRemoteObject.narrow(o, Sample.class);
			// Method Invocation
			System.out.println(sampleRef.message());
		}
		catch(Exception e) {}
	}
}