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Programming Stand-alone Clients

# Developing Clients for CORBA Objects

The following sections provide information on how to use the CORBA API:

- Enhancements to and Limitations of CORBA Object Types
- Making Outbound CORBA Calls: Main Steps
- Using the WebLogic ORB Hosted in JNDI
- Supporting Inbound CORBA Calls

# Enhancements to and Limitations of CORBA Object Types

The RMI-IIOP runtime is extended to support all CORBA object types (as opposed to RMI valuetypes) and CORBA stubs. Enhancements include:

- Support for out and in-out parameters
- Support for a call to a CORBA service from WebLogic Server using transactions and security
- Support for a WebLogic ORB hosted in JNDI rather than an instance of the JDK ORB used in previous releases

CORBA Object Type support has the following limitations:

- It should not be used to make calls from one WebLogic Server instance to another WebLogic Server instance.
- Clustering is not supported. If a clustered object reference is detected, WebLogic Server uses internal RMI-IIOP support to make the call. Out and in-out parameters will not be supported.
- CORBA services created by `ORB.connect()` result in a second object hosted inside the server. It is important that you use `ORB.disconnect()`to remove the object when it is no longer needed.

# Making Outbound CORBA Calls: Main Steps

Follow these steps to implement a typical development model for customers wanting to use the CORBA API for outbound calls.

1. Generate CORBA stubs from IDL using idlj, the JDKs IDL compiler.
2. Compile the stubs using javac.
3. Build EJB(s) including the generated stubs in the jar.
4. Use the WebLogic ORB hosted in JNDI to reference the external service.

# Using the WebLogic ORB Hosted in JNDI

This section provides examples of several mechanisms to access the WebLogic ORB. Each mechanism achieves the same effect and their constituent components can be mixed to some degree. The object returned by `narrow()` will be a CORBA stub representing the external ORB service and can be invoked as a normal CORBA reference. In the following code examples it is assumed that the CORBA interface is called MySvc and the service is hosted at "where" in a foreign ORB's CosNaming service located at `exthost:extport`:

## ORB from JNDI

>     .

>     .

>     .ORB orb = (ORB)new InitialContext().lookup("java:comp/ORB");

>     NamingContext nc = NamingContextHelper.narrow(orb.string_to_object("corbaloc:iiop:exthost:extport/NameService"));

>     MySvc svc = MySvcHelper.narrow( nc.resolve(new NameComponent[] { new NameComponent("where", "")}));

>     .

>     .

>     .

## Direct ORB creation

>     .

>     .

>     .

>     ORB orb = ORB.init();

>     MySvc svc = MySvcHelper.narrow(orb.string_to_object("corbaname:iiop:exthost:extport#where"));

>     .

>     .

>     .

## Using JNDI

>     .

>     .

>     .

>     MySvc svc = MySvcHelper.narrow(new InitialContext().lookup("corbaname:iiop:exthost:extport#where"));

>     .

>     .

>     .

The WebLogic ORB supports most client ORB functions, including DII (Dynamic Invocation Interface). To use this support, you must not instantiate a foreign ORB inside the server. This will not yield any of the integration benefits of using the WebLogic ORB.

# Supporting Inbound CORBA Calls

WebLogic Server also provides basic support for inbound CORBA calls as an alternative to hosting an ORB inside the server. To do this, you use `ORB.connect()` to publish a CORBA server inside WebLogic Server by writing an RMI-object that implements a CORBA interface. Given the MySVC examples above:

>     .

>     .

>     .

>     class MySvcImpl implements MvSvcOperations, Remote

>     {

>             public void do_something_remote() {}

>             public static main() {

>                     MySvc svc = new MySvcTie(this);

>                     InitialContext ic = new InitialContext();

>                     ((ORB)ic.lookup("java:comp/ORB")).connect(svc);

>                     ic.bind("where", svc);

>             }

>     }

>     .

>     .

>     .

When registered as a startup class, the CORBA service will be available inside the WebLogic Server CosNaming service at the location "where".