How to find Port numbers used by RMI application

Question

Hi, hope u all find me a solution, how to find port numbers used in the RMI application, that is port number which the RMI application communicates between RMIserver and RMIclient. ur answers would b highly appreciated

Answer 1

Currently RMI transport layer does not directly expose any public methods to get the listening ports of the exported RMI objects, but the application can always export RMI server objects at certain designated ports instead of relying on the RMI runtime by specifying them to UnicastRemoteObjcect at the time of exporting.
RMI transport layer try to optimize the number of listeing sockets by exporting all RMI server objects on a single port if no explicit ports were chosen. If the application is really interested in knowing the listeing ports, it can always specify the client and server socket factories to be used for creating Socket and ServerSocket to the RMI runtime at the time of exporting. When a RMI server object is exported, but the listening socket is not yet created, RMI transport layer invokes the createServerSocket(host, port) of server socket factory by passing the host and port details. If no explicit port is specified, underlying socket implementation choses anonymous port. At this point of time application can log these listeing ports to some log file.
Similarly when the stub to the remote object is de-serialized in the client address space, it does also contain the client socket factory along with the end point details (host, port and server object ID). RMI runtime in the client address space needs to establish connection with the remote server object, it try to get the socket from client socket factory by invoking createSocket() on the client socket factory. Now the application can call getLocalPort() on the socket before returning it to the RMI transport layer.
There is a undocumented class RMIStat to dump RMI runtime state information. It provides a lot of static methods to dump RMI state information like object table, transports, threads etc. You can download the source code of this utility from RMI archives, but remember this is not a comman-line utility, you must invoke these static methods as part of the application code.
-- Srinath Mandalapu