Remote Method Invocation by James Hunt, Joel Dominic, and Adam Mcculloch

CONTENT  What is RMI  Why is it used  How is it used

WHAT ARE OBJECTS Encapsulation of…  Data including pointers to other objects  Methods used to manipulate the data

WHAT DOES RMI REALLY MEAN? RMI stands of Remote Method Invocation Essentially allows for a client to perform operations on objects stored on a separate networked machine Idea for RMI taken from RPC or Remote Procedure Call  Basically just the Procedural Programming approach to RMI  Allows for procedures to be executed on a separately networked machine

COMMON USES/INTERFACES FOR RMI RMI is used in most distributed java applications  Solely in java originally  Has been ported to CORBA (Common Object Request Broker Architecture) CORBA allows RMI to be used by non java languages

HOW IT WORKS  A client machine will make a method call for remote objects that reside on a server  The server will then run that method on the object  Finally, the server will return the results of that method to the client

PASSING OBJECT PARAMETERS Serializing objects: In java (main language for RMI) objects must use the serializable interface  Everything within the object is encoded into a byte stream  Non primitive objects being encoded must also implement the serializable interface

STUBS and SKELETONS Stubs: Resides on client machine Contains:  Parent Object Reference  Method call  Parameters needed for execution Skeletons: Resides only on the server Unwraps the stub to be run server side Translates stubs into actual object calls

Diagram courtesy of:

Java code courtesy of:

SUMMARY  Client machine makes a method request on an object that resides on the Server  Client must pass in serialized objects as parameters and then use Stubs and Skeletons to wrap and unwrap these objects  Server passes information back to the client through serialized objects

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