RMI + java reflection

Question

I'm using RMI to allow access to my Java application via MATLAB, which runs in another JVM. MATLAB has a nice interface to print the methods of a Java object. But it fails with RMI, because the object it gets is a proxy.

So I would like to add my own method to extract/print the capability of a remote interface (RMI obviously can't directly access methods not available in exported remote interfaces).

How could I do this with reflection, either on the client end of the RMI connection, or on the server end? I don't have much experience using reflection. Use case below.

edit: what I'm getting most stuck on is given an arbitrary object X (including where X is an RMI proxy), how can I use reflection to obtain the interfaces implemented by that object?

java classes:

/** client-side remote describer */
class RemoteDescriber
{
    RemoteDescription describe(Remote remote) { ... }
}

/* representation of remote interfaces implemented by an object */
class RemoteDescription implements Serializable
{
    /* string representation of remote interfaces implemented by an object */
    @Override public String toString() { ... }

    /* maybe there are other methods permitting object-model-style navigation
     * of a remote interface
     */
}

interface FooRemote extends Remote
{
    /* some sample methods */
    public int getValue() throws RemoteException;
    public void setValue(int x) throws RemoteException;
    public void doSomethingSpecial() throws RemoteException;
    /* other methods omitted */        

    /** server-side */
    public RemoteDescription describe() throws RemoteException;        
}

and sample client session in MATLAB

x = ...;     % get something that implements FooRemote
describer = com.example.RemoteDescriber;
% describer is a client-side Java object

description1 = describer.describe(x)

%%% prints a description of the FooRemote interface 
%%% obtained by the client-side RemoteDescriber

description2 = x.describe()

%%% prints a description of the FooRemote interface 
%%% obtained on the server-side by x itself, and marshalled
%%% to the client

Answer 1

the objects on your client, you are right, are proxys, they are called stubs. to get the interfaces from it you should code something like this:

where o is your object. the interfaces belong to the "Class"-class

Class c = o.getClass();

Class[] theInterfaces = c.getInterfaces();

for (int i = 0; i < theInterfaces.length; i++) {

String interfaceName = theInterfaces[i].getName();

System.out.println(interfaceName);

}

stubs are auto generated therefore you should not implement something into them. but you could implement a method "getInformation" in your remote interfaces and every server object shoudl implement this and return a string which contains all information of the "server" object. and this method generates the string by getting information via reflection from the "this" object.