Networking with RMI - SCJD Exam with J2SE 5 - page 179

The RMI Implementation
To create a version of our server that acts as a factory, we first define the factory and its only
method, getClient() , which allows us to obtain a unique instance of the DvdDatabase class
(see Listing 6-4).

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Note In this section we are talking about using the Factory pattern with our RMI solution, but it would
work equally well with a sockets solution. However, the socket server already works essentially as a factory,
creating a unique thread for each connected client, so we don't really need to explicitly create a unique
object for each connected client. The very nature of a multithreaded socket server addresses the issue of
thread reuse in an RMI thread pool.

Listing 6-4. DvdDatabaseFactory.java

interface DvdDatabaseFactory extends Remote {
public DvdDatabaseRemote getClient() throws RemoteException;

}

class DvdDatabaseFactoryImpl extends UnicastRemoteObject
implements DvdDatabaseFactory {
/**
* A version number for this class so that serialization can occur
* without worrying about the underlying class changing between
* serialization and deserialization.
*/
private static final long serialVersionUID = 5165L;

public DvdDatabaseFactoryImpl() throws RemoteException {
//do nothing constructor

}

public DvdDatabaseRemote getClient() throws RemoteException {
return new DvdDatabaseImpl();

}

}

Now we define the DvdDatabase remote class, which like any other Remote object, extends
java.rmi.Remote in the interface and extends UnicastRemoteObject in the Implementation
class:

public interface DvdDatabaseRemote extends Remote, DBClient {
}
public class DvdDatabaseImpl extends UnicastRemoteObject implements
DvdDatabaseRemote {
... refer to code base for the rest of implementation...
}