Distribution strategies

  • NOTE: PEAA has a lot of outdated ideas, and tech and techinques have changed

What

  • Distributed processing is done by placing objects on different nodes(processes on different machines connected via networks)

  • Benefits

    • load can be distributed between different nodes, better performance ie throughput

    • Easier to add nodes (horizontal scaling and load balancing needed)

    • Calls between nodes are transparent and easy to follow

  • Dont distribute if you dont have to

    • This is not the case for a lot of cases, apart from fast performance requirements. As the benefits of distributing (see micros services) can out way the costs

    • Does apply to objects, this pattern has been deprecated (ie COBRA, DCOM etc). Instead use of messaging protocols, rest with json/xml, grpc are used now.

Types

  • Local call

    • calls between components on the same node

    • very fast

  • Remote call

    • calls between components on different machines

    • Calls need to be course grained

      • minimise remote function calls

    • slower

      • marshall and unmarshal data

      • data transfer over network (latency and unreliability/partitioning)

    • Now speed of calls of fast, so do a few does not matter, but if dealing lots of calls, despite the speed of the response, the law of big numbers will see slow down

  • OOP

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