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Distributed Configuration

Distributed Configuration. T.C Software + T.C. Hardware = One OS in a multiprocessor system (DOS) Communication : shared memory T.C. Software + L.C. Hardware = Homogeneous OS in network (DOS) Communication : message passing

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Distributed Configuration

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  1. Distributed Configuration • T.C Software + T.C. Hardware = One OS in a multiprocessor system (DOS) Communication: shared memory • T.C. Software + L.C. Hardware = Homogeneous OS in network (DOS) Communication: message passing • L.C. Software + L.C. Hardware = Heterogeneous OS in network (NOS) Communication: file sharing, network commands

  2. NOS & DOS

  3. Communications in NOS & DOS

  4. NOS->DOS transparency • L.C. Software + L.C. Hardware + Middleware: • NOS->DOS : • near really distributed system + complexity reduction

  5. Middlewares • 1. distributed file systems • file level transparency (remote file using) • 2. RPC • process level transparency (remote procedure call) • 3. distributed objects • object level transparency (remote object call) • 4. distributed documents (web) • document level transparency (remote document call)

  6. Communiction in middlewares like ORB

  7. T.C. software + L.C. hardware ->T.C software + T.C harwarewhy?communication by shared data(control mechanisms: semaphores , monitors)is easiercommunication by message(control mechanisms : algorithms:reliable group communication)

  8. Solution: virtual memory(DSM)

  9. Distrubution Architectures

  10. Multiprocessor architectures • A multiprocessor traffic control system

  11. characteristics • Simplest distributed system model. • System composed of multiple processes which may execute on different processors. • Architectural model of many large real-time systems. • Distribution of process to processor may be pre-ordered or may be under the control of a dispatcher.

  12. Client-server architectures

  13. Computers in a C/S network

  14. characteristics -The application is modelled as a set of services that are provided by servers and a set of clients that use these services. -Clients know of servers but servers need not know of clients. -Clients and servers are logical processes

  15. Film and picture library

  16. Logical design of C/S

  17. characteristics • Presentation layer • presenting the results of a computation to system users and with collecting user inputs. • Application processing layer • providing functionality e.g., in a banking system, banking functions such as open account, close account, etc. • Data management layer • managing the system databases.

  18. Thin and fat clients

  19. characteristics Thin:Used when legacy systems are migrated to client server architectures. The legacy system acts as a server with a graphical interface implemented on a client. Fat:suitable for new C/S systems where the capabilities of the client system are known in advance. More complex than a thin client model.

  20. Fat C/S

  21. New Approach(using mobile code: applet, activex Fat + Thin: A 3-tier C/S architecture

  22. characteristics • each of the application architecture layers may execute on a separate processor. • -better performance than a thin-client approach and is simpler to manage than a fat-client approach. • -A more scalable architecture - as demands increase, extra servers can be added.

  23. An internet banking system

  24. Use of C/S architectures

  25. Distributed object architectures

  26. characterictics No distinction between clients and servers. Each distributable entity is an object that provides services to other objects and receives services from other objects. Object communication: a middleware:ORB. More complex to design than C/S systems.

  27. Advantages allows to delay design decisions: where and how services should be provided. a very open system architecture: new resources to be added to it. The system is flexible and scaleable. reconfigure the system dynamically with objects migrating across the network as required.

  28. A data mining system • new types of relationship to be mined by adding new integrator objects.

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