JavaTM IDL Examples

This page contains a collection of minimal working examples:

Instructions for compiling and running the examples, whose source code is included in the Java IDL release, are also provided.

Example IDL

The example IDL shown below describes a CORBA object whose single sayHello() operation returns a string.

module HelloApp
{
    interface hello
    {
        string sayHello();
    };
};

Example Server

The example server consists of two classes, the servant and the server. The servant, helloServant, is the implementation of the hello IDL interface; each hello instance is implemented by a helloServant instance. The servant is a subclass of _helloImplBase, which is generated by the idltojava compiler from the example IDL. The servant contains one method for each IDL operation, in this example, just the sayHello() method. Servant methods are just like ordinary Java methods; the extra code to deal with the ORB, with marshaling arguments and results, and so on, is provided by the server and the stubs.

The server class has the server's main() method, which: 

// Copyright and License 
 
import HelloApp.*;
 
import org.omg.CosNaming.*;
import org.omg.CosNaming.NamingContextPackage.*;
import org.omg.CORBA.*;
 
class helloServant extends _helloImplBase 
{
    public String sayHello()
    {
	return "\nHello world !!\n";
    }
}
 
public class helloServer {
 
    public static void main(String args[])
    {
	try{
	    // create and initialize the ORB
	    ORB orb = ORB.init(args, null);
 
	    // create servant and register it with the ORB
	    helloServant helloRef = new helloServant();
	    orb.connect(helloRef);
 
	    // get the root naming context
	    org.omg.CORBA.Object objRef = 
		orb.resolve_initial_references("NameService");
	    NamingContext ncRef = NamingContextHelper.narrow(objRef);
 
	    // bind the Object Reference in Naming
	    NameComponent nc = new NameComponent("Hello", "");
	    NameComponent path[] = {nc};
	    ncRef.rebind(path, helloRef);
 
	    // wait for invocations from clients
            java.lang.Object sync = new java.lang.Object();
            synchronized (sync) {
                sync.wait();
            }
 
	} catch (Exception e) {
	    System.err.println("ERROR: " + e);
	    e.printStackTrace(System.out);
	}
    }
}

Example Application Client

The example application client below:

 

// Copyright and License 
 
import HelloApp.*;
import org.omg.CosNaming.*;
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");
            NamingContext ncRef = NamingContextHelper.narrow(objRef);
 
            // resolve the Object Reference in Naming
            NameComponent nc = new NameComponent("Hello", "");
            NameComponent path[] = {nc};
            hello helloRef = helloHelper.narrow(ncRef.resolve(path));
 
	    // call the hello server object and print results
	    String hello = helloRef.sayHello();
	    System.out.println(hello);
 
	} catch (Exception e) {
	    System.out.println("ERROR : " + e) ;
	    e.printStackTrace(System.out);
	}
    }
}
 

Example Applet Client

The example applet client below:

// Copyright and License 
 
import HelloApp.*;
 
import org.omg.CosNaming.*;
import org.omg.CosNaming.NamingContextPackage.*;
import org.omg.CORBA.*;
import java.awt.Graphics;
 
public class helloApplet extends java.applet.Applet 
{
    public void init() {
	try {
	    // create and initialize the ORB
            ORB orb = ORB.init(this, null);
 
            // get the root naming context
            org.omg.CORBA.Object objRef = 
		orb.resolve_initial_references("NameService");
            NamingContext ncRef = NamingContextHelper.narrow(objRef);
 
            // resolve the Object Reference in Naming
            NameComponent nc = new NameComponent("Hello", "");
            NameComponent path[] = {nc};
            hello helloRef = helloHelper.narrow(ncRef.resolve(path));
 
            // call the hello server object and print results
            message = helloRef.sayHello();
 
	} catch (Exception e) {
	    System.out.println("HelloApplet exception: " + e.getMessage());
	    e.printStackTrace(System.out);
        }
    }
 
    public void paint(Graphics g) 
    {
	g.drawString(message, 25, 50);
    }
 
    String message = "";
}

Building and Running the Examples

The source code for the examples is located in ${JAVAIDL_HOME}/examples/hello, where JAVAIDL_HOME is the directory in which Java IDL is installed. The following instructions assume you can use port 1050 for the Java IDL name server. Substitute a different port if necessary.