JAX-RPC EJB End points doubt in xyzws

[Divya Gehlot]

Hi,
I was going through xyzws notes and got some controversial statement

 The endpoint interface MUST comply with the rules for WSDL-to-Java mapping defined by the JAX-RPC specification. Every business method defineed in the endpoint interface[B] MUST declare the java.rmi.RemoteException in its throw clause   [/B]

Although the bean class MUST implement all methods with the same signature defined in the endpoint interface, it�s not required to explicit implement the interface itself. This is in keeping with the EJB platform convetion of not implementing remote or local interfaces. Each methods in [B]the implementation class MUST throw the same exceptions defined in endpoint interface throw � except one: java.rmi.RemorteException[/B]. The endpoint bean�s methods MUST NEVER declare RemoteException.   

please clarify .

[sajan sachin]

Divya,

The endpoint interface must throw remote exception,
but the implementation for that endpoint interface should not throw remote exception,because remote exception is something which is thrown by the server and not by the implementation class,since the implementation class resides in the server we should not throw remote exception from our implementation class only the server throws it.But in the endpoint interface this is not the case,think like ,the client will call only methods in the endpoint interface and the client should be aware of the remote exception,that is why we need to throw remote exception from the endpoint interface.

Thanks,
Sajan C

[Peer Reynders]

I think you mean "contradictory" not "controversial".

And the statements aren't contradictory - they are in fact complimentary.

The endpoint interface is a remote interface as seen by the client and therefore losing the remote connection is always a possibility. If the connection is lost or cannot be created the client's application server throws a subclass of java.rmi.RemoteException. Note this exception isn't coming from the implementing bean.

The implementing bean on the other hand "lives" on the application server that is running the service (not the client's application server) and therefore doesn't know about any of the connection problems that the client may be having. Throwing of java.rmi.RemoteExceptions is entirely the responsibility of the client's application server. The bean is only allowed to throw "application exceptions" (which show up in the WSDL as SOAP Faults) which cannot derive from java.rmi.RemoteExceptions.


Basically the rules state that java.rmi.RemoteException (or a subclass thereof) cannot be used to represent an "application exception" but must always be treated as a "system exception".

Enterprise JavaBeans, 3rd Edition: 14.6.1. Application Exceptions Versus System Exceptions

An application exception is any exception that does not extend java.lang.RuntimeException or java.rmi.RemoteException. System exceptions are java.lang.RuntimeException and its subtypes, including EJBException.

An application exception must never extend either the RuntimeException, the RemoteException, or one of their subtypes.

[Divya Gehlot]

Hi Peer,
Thanks
I understood