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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?.
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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: http://www.cs.uiowa.edu/~slonnegr/wpj/RMI.pdf
Java code courtesy of: http://download.oracle.com/javase/tutorial/rmi/implementing.html
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
SOURCES • http://www.cs.uiowa.edu/~slonnegr/wpj/RMI.pdf • http://www.oracle.com/technetwork/java/javase/tech/index-jsp-136424.html • http://download.oracle.com/javase/tutorial/rmi/index.html • http://download.oracle.com/javase/tutorial/rmi/implementing.html • http://www.daimi.au.dk/~mailund/scripting2005/lecture-notes/rmi.html • http://notes.corewebprogramming.com/student/RMI.pdf • http://infolab.stanford.edu/CHAIMS/Doc/Details/Protocols/rmi/rmi_description.html • http://www.javacamp.org/moreclasses/rmi/rmi22.html • http://www.sentex.net/~pkomisar/RMI.html • http://java.sun.com/developer/technicalArticles/ALT/sockets/