Server crashes will be transparent to entity bean clients?

[Alibabra Sanjie]

Server crashes will be transparent to entity bean clients? How about stateful or stateless session bean?

[Alibabra Sanjie]

I believe that Entity bean and stateless bean. What do you think?
[ May 07, 2004: Message edited by: Alibabra Sanjie ]

[Roger Chung-Wee]

A server crash is not necessarily transparent to a client as a client may receive an exception if it calls an entity object in a container that has experienced a crash.
A remote client receives the java.rmi.RemoteException and a local client receives the javax.ejb.EJBException. The exception can be thrown by the communication subsystem between the client and the Container.

[Alibabra Sanjie]

...I believe that Entity bean and stateless bean...

Actually that's one of the mock exam question. Most of the server may has hi-availability - one server down, backup server will start to serve the request. It may or may not transparent to the client. Since stateless bean can always get a neutral bean instance from the pool to serve the client, it can survive in the server crash. Since entity and primary key can survive in server crash, the entity bean can also survive in server crash. Correct me if I am wrong.

[Nileesha Bojjawar]

Hi,
Will the standby server create a new EJBObject for the crashed entity ? If the client is refering to a EJBObject on one server and that server crashes What will happen to his stub? will the server correlate the new ejbobject to this stub?
I am a newbee to EJB's Please clarify.
Thanks

[Alibabra Sanjie]

How the server will recover from the crash, or using the hi-availability is vendor specific, and it's beyond the spec. But due to the nature of the stateless bean and entity bean, it's possible for them to recover or survive from the server crash and can be transparent. That's what I think. I raised the question to make sure. Any further comments?