An application that access CORBA service using JIDL

Aim: Write an CORBA application using JAVA IDL

Required programs:

• IDL file(interface) for simple HelloWorld


• A Server class


• A Client class

Defining the Interface (Hello.idl)

Hello.idl

module HelloApp

{

  interface Hello

  {

  string sayHello();

  oneway void shutdown();

  };

};

Implementing the Server (HelloServer.java)

HelloServer.java

import HelloApp.*;

import org.omg.CosNaming.*;

import org.omg.CosNaming.NamingContextPackage.*;

import org.omg.CORBA.*;

import org.omg.PortableServer.*;

import org.omg.PortableServer.POA;

import java.util.Properties;

class HelloImpl extends HelloPOA{

  private ORB orb;

  public void setORB(ORB orb_val){

    orb = orb_val;

  }

 

  public String sayHello(){

    return "\nHello world !!\n";

  }

 

  public void shutdown(){

    orb.shutdown(false);

  }

}

public class HelloServer{

  public static void main(String args[]){

    try{

      // create and initialize the ORB

      ORB orb = ORB.init(args, null);

      // Get reference to rootpoa & activate the POAManager

      POA rootpoa = POAHelper.narrow(orb.resolve_initial_references("RootPOA"));

      rootpoa.the_POAManager().activate();

      // create servant and register it with the ORB

      HelloImpl helloImpl = new HelloImpl();

      helloImpl.setORB(orb);

      // create a tie, with servant being the delegate.

      HelloPOATie tie = new HelloPOATie(helloImpl, rootpoa);

      // obtain the objectRef for the tie

      // this step also implicitly activates the

      // the object

      Hello href = tie._this(orb);

           

      // get the root naming context

      org.omg.CORBA.Object objRef = orb.resolve_initial_references("NameService");

     

      // Use NamingContextExt which is part of the Interoperable

      // Naming Service specification.

      NamingContextExt ncRef = NamingContextExtHelper.narrow(objRef);

      // bind the Object Reference in Naming

      String name = "Hello";

      NameComponent path[] = ncRef.to_name( name );

      ncRef.rebind(path, href);

      System.out.println("HelloServer ready and waiting ...");

      // wait for invocations from clients

      orb.run();

      }

     

    catch (Exception e){

      System.err.println("ERROR: " + e);

      e.printStackTrace(System.out);

    }

   

    System.out.println("HelloServer Exiting ...");

       

  }

}

Implementing the Client Application (HelloClient.java)

HelloClient.java

import HelloApp.*;

import org.omg.CosNaming.*;

import org.omg.CosNaming.NamingContextPackage.*;

import org.omg.CORBA.*;

public class HelloClient{

  public static void main(String args[]){

 

    try{

      // create and initialize the ORB

      ORB orb = ORB.init(args, null);

      // get the root naming context

      org.omg.CORBA.Object objRef =

          orb.resolve_initial_references("NameService");

         

      // Use NamingContextExt instead of NamingContext. This is

      // part of the Interoperable naming Service. 

      NamingContextExt ncRef = NamingContextExtHelper.narrow(objRef);

      // resolve the Object Reference in Naming

      String name = "Hello";

      Hello helloImpl = HelloHelper.narrow(ncRef.resolve_str(name));

      System.out.println("Obtained a handle on server object: " + helloImpl);

      System.out.println(helloImpl.sayHello());

      helloImpl.shutdown();

      }

     

    catch (Exception e) {

      System.out.println("ERROR : " + e) ;

      e.printStackTrace(System.out);

    }

  }

}

Building and Running The Application

To run this client-server application on your development machine:

1. Change to the directory that contains the file Hello.idl.


2. Run the IDL-to-Java compiler, idlj, twice on the IDL file to create stubs and skeletons. This step assumes that you have included the path to the java/bin directory in your path.

3.    idlj -fall  Hello.idl

4.    idlj -fallTie Hello.idl

• It generates

• HelloPOA.java


• _HelloStub.java


• Hello.java


• HelloHelper.java


• HelloHolder.java


• HelloOperations.java

5. Compile the .java files, including the stubs and skeletons (which are in the directory HelloApp). This step assumes the java/bin directory is included in your path.

6.     javac *.java HelloApp/*.java

7. Start orbd.

  start orbd -ORBInitialPort 1050 -ORBInitialHost localhost

8. Start the Hello server.

start java HelloServer -ORBInitialPort 1050 -ORBInitialHost localhost

9. Run the client application:

 java HelloClient -ORBInitialPort 1050 -ORBInitialHost localhost

output:

Obtained a handle on server object: IOR:000000000000001749444c3a48656c6c6f417070

2f48656c6c6f3a312e300000000000010000000000000082000102000000000a3132372e302e302e

3100055a00000031afabcb00000000203a12163f00000001000000000000000100000008526f6f74

504f4100000000080000000100000000140000000000000200000001000000200000000000010001

00000002050100010001002000010109000000010001010000000026000000020002

Hello world !!