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Distributed Objects

Distributed Objects. distributed objects - objects which reside on different machines/ network architectures, benefits, drawbacks implementation of a remote object system . Design large systems - avoid bottlenecks and single points of failure

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Distributed Objects

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  1. Distributed Objects

  2. distributed objects - objects which reside on different machines/ network • architectures, benefits, drawbacks • implementation of a remote object system 

  3. Design large systems - avoid bottlenecks and single points of failure • Distributed: partition system into autonomic subsystems, self-contained, with clear relations (interfaces) • Subsystem may be on different host, communicate by networking protocols

  4. active object model • objects reside on different RTE's • send messages to one to another • how two objects are going to communicate? • remote method invocation: OO concept • objects in different environments communicate=send messages

  5. RMI Architecture in Java • framework for remote method invocation • abstract subsystem A as providing a service=an interface • interface used by subsystem, B, in a different JVM - invoke methods of A.

  6. example • class, representing a printing service. • support printing lines of text sent to them • from other objects, which reside on different JVMs, on different hosts.

  7.  interface of the service

  8. remote interface supports remote method invocations

  9. communication throws section

  10. Implementing the Interface • implementing the remote interface •  tell Java how this class is going to communicate remotely

  11. Make the Service Available • instantiate Object of this class • wait for messages from other RTE: • Instantiate LinePrinterImpl Object, L. • Make L available for remote invocations • Wait for remote invocations, and call the appropriate methods of L.

  12. user needs to locate where on which host and JVM printer object is located. • process does not exit when the main function completes • naming.rebind(name, object) - executor is created - waits for messages and executes

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