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package examples.rmi_iiop.hello

hello example package

RMI interface

HelloWorld

Implementation class

HelloImpl

Java client

HelloClient

C++ client

HelloClient

about this example

This example illustrates:

Creating an RMI remote object
Separation of RMI classes and CORBA classes
Using the RMI compiler to generate an IDL
Compiling the IDL to obtain client-side stubs and helper classes
Using the utils.host2ior utility to produce the server's Inter-operable Object Reference (IOR)
Accessing an RMI object from a CORBA client (Java and C++ client)

The example demonstrates connectivity between an RMI server and a CORBA client. In this example, a remote object is created and accessed by two types of CORBA clients, a Java client and a C++ client. Both clients are "IDL clients" developed using the CORBA/ CosNaming programming model and therefore do not require any WebLogic classes. The remote object, HelloImpl, is created implementing the HelloWorld interface. The WebLogic RMI compiler is used to create IDL file that defines the HelloWorld interface. The HelloWorld.idl file is then used to create stubs and helper classes appropriate for the type of client. Intructions for building and running the Java CORBA client are included below. See C++ client for instructions on building and running the C++ CORBA client.

In this example, the Java client was created to use VisiBroker for Java, version 3.4. You will need to have a copy of VisiBroker for Java installed on your machine to run this example. Since RMI over IIOP is only supported under the 1.3 JVM, you must run WebLogic Server using the 1.3 JVM.

how to use this example

Build the example:

Build the RMI object

Set up your development shell, as described in Setting up your environment.
Compile the RMI interface and implementation class as shown in this example for Windows NT:
```
  $ javac -d %SERVER_CLASSES% HelloWorld.java HelloImpl.java
```
Run the RMI compiler on the implementation class as show in this example for Windows NT:
```
  $ java weblogic.rmic -d %SERVER_CLASSES% -idl 
     -idlDirectory idlSource examples.rmi_iiop.hello.HelloImpl
```
The step above generates a HelloWorld.idl file in the /idlSource/examples/rmi_iiop/hello directory below the current directory. Since the HelloWorld interface extends java.rmi.Remote, a Remote.idl file is also generated in the /idlSource/java/rmi directory below the current directory.

Build the client

Now that you have an IDL describing the remote interface, you can build your CORBA client application. Package and class names can be repeated on the server- and client- side, particularly with the class that defines the remote interface. Since the RMI object and the CORBA client have different type systems, the class that defines the interface for the server-side will be very different from the class that defines the interface on the client-side. Because of this, it is essential that your CLASSPATH does not include the RMI object classes when building or running the client. The following steps create a new development environment prior to building and running the client.

Create a directory for the CORBA client classes named corbaclient under the /myserver directory in your WebLogic Server distribution.
Create a new command shell and set the CLASSPATH and PATH as shown in this example for Windows NT (from the point forward, this shell will be refered to as the "client shell").
```
  $ set CLASSPATH=JavaHome\lib\classes.zip;
        WebLogicHome\myserver\corbaclient;
        VisiBrokerHome\lib\vbjcosnm.jar;
        VisiBrokerHome\lib\vbjorb.jar;
        VisiBrokerHome\lib\vbjapp.jar

  $ set PATH=JavaHome\bin;VisiBrokerHome\bin
```
where:

JavaHome
Installation directory of your JDK (this entry may be omitted if you are using Java2)
WebLogicHome
Installation directory of WebLogic Server
VisiBrokerHome
Installation directory of VisiBroker for Java 3.4
Notice that the client application does not require any WebLogic classes. The /weblogic/myserver/corbaclient directory is included in the classpath only as a repository for the client classes created in this example.
Both the HelloWorld.idl and the Remote.idl files contain the directive #include orb.idl. If your ORB vendor has provided an orb.idl file, you should add the directory containing orb.idl to the include path when running the IDL compiler. The orb.idl that is shipped in the /weblogic/lib directory is intended to work with ORBs that support Objects-By-Value. Since VisiBroker 3.4 does not support Objects-By-Value and does not provide its own orb.idl, you will need to comment-out the #include orb.idl line from the HelloWorld.idl and Remote.idl files prior to performing the following step.
In the client shell, cd to this directory and compile the HelloWorld.idl file with the VisiBroker idl2java utility as shown in this example for Windows NT:
```
  $ idl2java -IidlSource idlSource\examples\rmi_iiop\hello\HelloWorld.idl
```
The step above generates additional Java classes into the subdirectory \examples\rmi_iiop\hello underneath the current directory. In the client shell, compile the generated files as shown in this examples for Windows NT:
```
  $ javac -d WebLogicHome\myserver\corbaclient examples\rmi_iiop\hello\*.java
```
where WebLogicHome is the WebLogic Server installation directory.
In the client shell, compile HelloClient as shown in this example for Windows NT:
```
  $ javac -d WebLogicHome\myserver\corbaclient HelloClient.java
```
where WebLogicHome is the WebLogic Server installation directory.

Configure the server:

Configure the implementation class as a startup class by adding the following line in the weblogic.properties file:
```
  weblogic.system.startupClass.hello=examples.rmi_iiop.hello.HelloImpl
```

Run the example:

Start the WebLogic Server in a new command shell using JDK 1.3.
Obtain the WebLogic Server Inter-operable Object Reference (IOR) by running the host2ior utility in the command shell that you compiled the RMI object as shown in this example for Windows NT:
```
  $ java utils.host2ior hostname port
```
where:

hostname
Host name of the WebLogic Server
port
Port where the WebLogic Server is listening for connections (weblogic.system.ListenPort).
The WebLogic Server IOR will be returned to the console. Select and copy the IOR to the clipboard. The console may insert line breaks into the IOR where it wraps to the next line. You must remove the linebreaks before pasting the IOR into the command-line argument list of an RMI over IIOP example. You can remove the line breaks by pasting into the IOR into an text editor, deleting the linebreaks, then re-copying the IOR to the clipboard.
In the client shell, run the HelloClient client with the following command:
```
  $ java examples.rmi_iiop.hello.HelloClient ServerIOR
```
where ServerIOR is the IOR you obtained by running the host2ior utility.
You should see "Hello world!!!" printed in the command shell running the server. The server will throw two java.net.SocketExceptions. This is the expected behavior, when the socket is closed by a client application.

there's more...

Read more about WebLogic RMI over IIOP in the Developer Guide, Using WebLogic RMI over IIOP.

Read more about WebLogic RMI in the Developer Guide, Using WebLogic RMI.

Last updated 3/7/2000