Question

Does a RemoteObject method’s return object has to be a serializable?
For example, A is a remote object and has the function:

SomeObject getMyObject() throws java.rmi.RemoteException

does SomeObject have to be serializable?

Answer 1

Well according to the docs it should be:

2.6 Parameter Passing in Remote Method Invocation

An argument to, or a return value from, a remote object can be any
object that is serializable. This includes primitive types, remote
objects, and non-remote objects that implement the
java.io.Serializable interface. For more details on how to make
classes serializable, see the “Java Object Serialization
Specification.” Classes, for parameters or return values, that are not
available locally are downloaded dynamically by the RMI system. See
the section on “Dynamic Class Loading” for more information on how RMI
downloads parameter and return value classes when reading parameters,
return values and exceptions.

http://docs.oracle.com/javase/1.5.0/docs/guide/rmi/spec/rmi-objmodel7.html

And this makes sense. The Object should transmitted from one node to the other. In order to be transmitted, it should be placed in a socket (at some point), so it should serialized.