CODEWITHSUNDEEP
javarmi
lledr
lledr

Reputation: 552

RMI and references / Proxy classes

As far as I can see, given a IFoo interface extending Remote and a FooImpl class implementing IFoo, the following two code fragments are (almost) equivalent : (1)

IFoo stub = ( IFoo )UnicastRemoteObject.exportObject( new FooImpl() );
Naming.bind( "foo", stub );

and, if FooImpl is a class that extends UnicastRemoteObject : (2)

Naming.bind( "foo", new FooImpl() );

In fact, the FooImpl instance exportation is done in the implicit UnicastRemoteObject constructor call.

But in (1), the object returned by UnicastRemoteObject.exportObject() is a Proxy (dynamic) class, and consequently the object recorded in the RMI registry is obviously a reference. Whereas in (2), it is not clear.

Where is the Proxy construction based an a FooImpl instance realized ? I have seen that the RMI registry management in the client code (Naming.bind()) encapsulates a (registry) Proxy class creation with a call to LocateRegistry.getRegister(). So in the request :

Naming.bind( "foo", new FooImpl() )

is it the registry Proxy class invocation handler that handles the parameters extending Remote to transform them as references / Proxy classes ?

And in that case, given that the stub Proxy class in (1) is itself a Remote class, would that mean that the object stored in the registry is a reference to a reference (i.e. a Proxy calling another Proxy calling the real class) ?

Thanks.

Upvotes: 1

Views: 832

Answers (1)

user207421
user207421

Reputation: 311023

When the FooImpl object is marshalled to the Registry in the bind() call it is automatically replaced by its stub. That happens for any exported remote object when used as a parameter or result of a remote method.

Upvotes: 3

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