Program is based on typically coarse-grain tasks
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Separate address space and a processor number for each task
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Data shared by explicit messages
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Point-to-point and collective communications patterns
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Examples: MPI, PVM, Occam for parallel computing
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Universal model for distributed computing to link naturally decomposed parts e.g. HTTP, RMI, IIOP etc. are all message passing
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distributed object technology (COM, CORBA) built on functionally concurrent objects sending and receiving messages
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Advantages:
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Close to hardware ALWAYS
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Can be close to problem as in distributed objects or functional parallelism
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Disadvantages:
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Many low-level details when NOT close to problem.
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