• Source: Java remote method invocation

The Java Remote Method Invocation (Java RMI) is a Java API that performs remote method invocation, the object-oriented equivalent of remote procedure calls (RPC), with support for direct transfer of serialized Java classes and distributed garbage-collection.
The original implementation depends on Java Virtual Machine (JVM) class-representation mechanisms and it thus only supports making calls from one JVM to another. The protocol underlying this Java-only implementation is known as Java Remote Method Protocol (JRMP). In order to support code running in a non-JVM context, programmers later developed a CORBA version.
Usage of the term RMI may denote solely the programming interface or may signify both the API and JRMP, IIOP, or another implementation, whereas the term RMI-IIOP (read: RMI over IIOP) specifically denotes the RMI interface delegating most of the functionality to the supporting CORBA implementation.
The basic idea of Java RMI, the distributed garbage-collection (DGC) protocol, and much of the architecture underlying the original Sun implementation, come from the "network objects" feature of Modula-3.




Generalized code


The programmers of the original RMI API generalized the code somewhat to support different implementations, such as a HTTP transport. Additionally, the ability to pass arguments "by value" was added to CORBA in order to be compatible with the RMI interface. Still, the RMI-IIOP and JRMP implementations do not have fully identical interfaces.
RMI functionality comes in the package java.rmi, while most of Sun's implementation is located in the sun.rmi package. Note that with Java versions before Java 5.0 developers had to compile RMI stubs in a separate compilation step using rmic. Version 5.0 of Java and beyond no longer require this step.




Jini version


Jini offers a more advanced version of RMI in Java. It functions similarly but provides more advanced security, object discovery capabilities, and other mechanisms for distributed object applications.




Example


The following classes implement a simple client-server program using RMI that displays a message.

RmiServerIntf interface
defines the interface that is used by the client and implemented by the server.

RmiServer class
listens to RMI requests and implements the interface which is used by the client to invoke remote methods.

RmiClient class
this is the client which gets the reference (a proxy) to the remote object living on the server and invokes its method to get a message. If the server object implemented java.io.Serializable instead of java.rmi.Remote, it would be serialized and passed to the client as a value.

Before running this example, we need to make a 'stub' file for the interface we used. For this task we have the RMI compiler - 'rmic'

Note: we make a stub file from the '*.class' file with the implementation of the remote interface, not from the '*.java' file.
rmic RmiServer

Note that since version 5.0 of J2SE support for dynamically generated stub files has been added, and rmic is only provided for backwards compatibility with earlier runtimes, or for programs that don't provide an explicit port number (or zero) when exporting remote objects, which is required for generated stubs to be possible, as described in the Javadoc for UnicastRemoteObject. See the comment in the constructor above.




References






External links


"Remote Method Invocation Home". Oracle Technology Network for Java Developers. Redwood Shores, CA, USA: Oracle Corporation. Retrieved 2014-07-14.
The Java RMI tutorial - a good starting point to learn RMI. Also check the Hello World in RMI
the Java RMI online training - Very good for training JavaRMI and as reference
The RMI page in the JDK docs
java.rmi (Sun's Java API Reference for the RMI package)
Ann Wollrath; Roger Riggs; Jim Waldo. "A Distributed Object Model for the Java System" (PDF). Archived (PDF) from the original on 2022-10-10. Retrieved 2009-02-11.
Programming WebLogic RMI - an introduction to RMI in Oracle Weblogic.
General Remote Method Invocation

Kata Kunci Pencarian:

• J sharp
• Java remote method invocation
• Remote procedure call
• Distributed object communication
• RMI-IIOP
• Java (programming language)
• Java Platform, Standard Edition
• Java Management Extensions
• Skeleton (computer programming)
• Java version history
• API