DISTRIBUTED SYSTEMS Principles and Paradigms Second Edition ANDREW S. TANENBAUM MAARTEN VAN STEEN

DISTRIBUTED SYSTEMS Principles and Paradigms Second Edition ANDREW S. TANENBAUM MAARTEN VAN STEEN

اسلاید 1: Tanenbaum & Van Steen, Distributed Systems: Principles and Paradigms, 2e, (c) 2007 Prentice-Hall, Inc. All rights reserved. 0-13-239227-5DISTRIBUTED SYSTEMS Principles and Paradigms Second Edition ANDREW S. TANENBAUM MAARTEN VAN STEEN Chapter 4 Communication

اسلاید 2: Tanenbaum & Van Steen, Distributed Systems: Principles and Paradigms, 2e, (c) 2007 Prentice-Hall, Inc. All rights reserved. 0-13-239227-5Layered Protocols (1)Figure 4-1. Layers, interfaces, and protocols in the OSI model.

اسلاید 3: Tanenbaum & Van Steen, Distributed Systems: Principles and Paradigms, 2e, (c) 2007 Prentice-Hall, Inc. All rights reserved. 0-13-239227-5Layered Protocols (2)Figure 4-2. A typical message as it appears on the network.

اسلاید 4: Tanenbaum & Van Steen, Distributed Systems: Principles and Paradigms, 2e, (c) 2007 Prentice-Hall, Inc. All rights reserved. 0-13-239227-5Middleware ProtocolsFigure 4-3. An adapted reference model for networked communication.

اسلاید 5: Tanenbaum & Van Steen, Distributed Systems: Principles and Paradigms, 2e, (c) 2007 Prentice-Hall, Inc. All rights reserved. 0-13-239227-5Types of CommunicationFigure 4-4. Viewing middleware as an intermediate (distributed) service in application-level communication.

اسلاید 6: Tanenbaum & Van Steen, Distributed Systems: Principles and Paradigms, 2e, (c) 2007 Prentice-Hall, Inc. All rights reserved. 0-13-239227-5Conventional Procedure CallFigure 4-5. (a) Parameter passing in a local procedure call: the stack before the call to read. (b) The stack while the called procedure is active.

اسلاید 7: Tanenbaum & Van Steen, Distributed Systems: Principles and Paradigms, 2e, (c) 2007 Prentice-Hall, Inc. All rights reserved. 0-13-239227-5Client and Server StubsFigure 4-6. Principle of RPC between a client and server program.

اسلاید 8: Tanenbaum & Van Steen, Distributed Systems: Principles and Paradigms, 2e, (c) 2007 Prentice-Hall, Inc. All rights reserved. 0-13-239227-5Remote Procedure Calls (1)A remote procedure call occurs in the following steps:The client procedure calls the client stub in the normal way.The client stub builds a message and calls the local operating system.The client’s OS sends the message to the remote OS.The remote OS gives the message to the server stub.The server stub unpacks the parameters and calls the server. Continued …

اسلاید 9: Tanenbaum & Van Steen, Distributed Systems: Principles and Paradigms, 2e, (c) 2007 Prentice-Hall, Inc. All rights reserved. 0-13-239227-5Remote Procedure Calls (2)A remote procedure call occurs in the following steps (continued):The server does the work and returns the result to the stub.The server stub packs it in a message and calls its local OS.The server’s OS sends the message to the client’s OS.The client’s OS gives the message to the client stub.The stub unpacks the result and returns to the client.

اسلاید 10: Tanenbaum & Van Steen, Distributed Systems: Principles and Paradigms, 2e, (c) 2007 Prentice-Hall, Inc. All rights reserved. 0-13-239227-5Passing Value Parameters (1)Figure 4-7. The steps involved in a doing a remote computation through RPC.

اسلاید 11: Tanenbaum & Van Steen, Distributed Systems: Principles and Paradigms, 2e, (c) 2007 Prentice-Hall, Inc. All rights reserved. 0-13-239227-5Passing Value Parameters (2)Figure 4-8. (a) The original message on the Pentium.

اسلاید 12: Tanenbaum & Van Steen, Distributed Systems: Principles and Paradigms, 2e, (c) 2007 Prentice-Hall, Inc. All rights reserved. 0-13-239227-5Passing Value Parameters (3)Figure 4-8. (a) The original message on the Pentium.

اسلاید 13: Tanenbaum & Van Steen, Distributed Systems: Principles and Paradigms, 2e, (c) 2007 Prentice-Hall, Inc. All rights reserved. 0-13-239227-5Passing Value Parameters (4)Figure 4-8. (c) The message after being inverted. The little numbers in boxes indicate the address of each byte.

اسلاید 14: Tanenbaum & Van Steen, Distributed Systems: Principles and Paradigms, 2e, (c) 2007 Prentice-Hall, Inc. All rights reserved. 0-13-239227-5Parameter Specification and Stub GenerationFigure 4-9. (a) A procedure. (b) The corresponding message.

اسلاید 15: Tanenbaum & Van Steen, Distributed Systems: Principles and Paradigms, 2e, (c) 2007 Prentice-Hall, Inc. All rights reserved. 0-13-239227-5Asynchronous RPC (1)Figure 4-10. (a) The interaction between client and server in a traditional RPC.

اسلاید 16: Tanenbaum & Van Steen, Distributed Systems: Principles and Paradigms, 2e, (c) 2007 Prentice-Hall, Inc. All rights reserved. 0-13-239227-5Asynchronous RPC (2)Figure 4-10. (b) The interaction using asynchronous RPC.

اسلاید 17: Tanenbaum & Van Steen, Distributed Systems: Principles and Paradigms, 2e, (c) 2007 Prentice-Hall, Inc. All rights reserved. 0-13-239227-5Asynchronous RPC (3)Figure 4-11. A client and server interacting through two asynchronous RPCs.

اسلاید 18: Tanenbaum & Van Steen, Distributed Systems: Principles and Paradigms, 2e, (c) 2007 Prentice-Hall, Inc. All rights reserved. 0-13-239227-5Writing a Client and a Server (1)Figure 4-12. The steps in writing a client and a server in DCE RPC.

اسلاید 19: Tanenbaum & Van Steen, Distributed Systems: Principles and Paradigms, 2e, (c) 2007 Prentice-Hall, Inc. All rights reserved. 0-13-239227-5Writing a Client and a Server (2)Three files output by the IDL compiler: A header file (e.g., interface.h, in C terms).The client stub.The server stub.

اسلاید 20: Tanenbaum & Van Steen, Distributed Systems: Principles and Paradigms, 2e, (c) 2007 Prentice-Hall, Inc. All rights reserved. 0-13-239227-5Binding a Client to a Server (1)Registration of a server makes it possible for a client to locate the server and bind to it. Server location is done in two steps:Locate the server’s machine.Locate the server on that machine.

اسلاید 21: Tanenbaum & Van Steen, Distributed Systems: Principles and Paradigms, 2e, (c) 2007 Prentice-Hall, Inc. All rights reserved. 0-13-239227-5Binding a Client to a Server (2)Figure 4-13. Client-to-server binding in DCE.

اسلاید 22: Tanenbaum & Van Steen, Distributed Systems: Principles and Paradigms, 2e, (c) 2007 Prentice-Hall, Inc. All rights reserved. 0-13-239227-5Berkeley SocketsFigure 4-14. The socket primitives for TCP/IP.

اسلاید 23: Tanenbaum & Van Steen, Distributed Systems: Principles and Paradigms, 2e, (c) 2007 Prentice-Hall, Inc. All rights reserved. 0-13-239227-5The Message-Passing Interface (1)Figure 4-15. Connection-oriented communication pattern using sockets.

اسلاید 24: Tanenbaum & Van Steen, Distributed Systems: Principles and Paradigms, 2e, (c) 2007 Prentice-Hall, Inc. All rights reserved. 0-13-239227-5The Message-Passing Interface (2)Figure 4-16. Some of the most intuitive message-passing primitives of MPI.

اسلاید 25: Tanenbaum & Van Steen, Distributed Systems: Principles and Paradigms, 2e, (c) 2007 Prentice-Hall, Inc. All rights reserved. 0-13-239227-5Message-Queuing Model (1)Figure 4-17. Four combinations for loosely-coupled communications using queues.

اسلاید 26: Tanenbaum & Van Steen, Distributed Systems: Principles and Paradigms, 2e, (c) 2007 Prentice-Hall, Inc. All rights reserved. 0-13-239227-5Message-Queuing Model (2)Figure 4-18. Basic interface to a queue in a message-queuing system.

اسلاید 27: Tanenbaum & Van Steen, Distributed Systems: Principles and Paradigms, 2e, (c) 2007 Prentice-Hall, Inc. All rights reserved. 0-13-239227-5General Architecture of a Message-Queuing System (1)Figure 4-19. The relationship between queue-level addressing and network-level addressing.

اسلاید 28: Tanenbaum & Van Steen, Distributed Systems: Principles and Paradigms, 2e, (c) 2007 Prentice-Hall, Inc. All rights reserved. 0-13-239227-5General Architecture of a Message-Queuing System (2)Figure 4-20. The general organization of a message-queuing system with routers.

اسلاید 29: Tanenbaum & Van Steen, Distributed Systems: Principles and Paradigms, 2e, (c) 2007 Prentice-Hall, Inc. All rights reserved. 0-13-239227-5Message BrokersFigure 4-21. The general organization of a message broker in a message-queuing system.

اسلاید 30: Tanenbaum & Van Steen, Distributed Systems: Principles and Paradigms, 2e, (c) 2007 Prentice-Hall, Inc. All rights reserved. 0-13-239227-5IBM’s WebSphere Message-Queuing SystemFigure 4-22. General organization of IBM’s message-queuing system.

اسلاید 31: Tanenbaum & Van Steen, Distributed Systems: Principles and Paradigms, 2e, (c) 2007 Prentice-Hall, Inc. All rights reserved. 0-13-239227-5ChannelsFigure 4-23. Some attributes associated with message channel agents.

اسلاید 32: Tanenbaum & Van Steen, Distributed Systems: Principles and Paradigms, 2e, (c) 2007 Prentice-Hall, Inc. All rights reserved. 0-13-239227-5Message Transfer (1)Figure 4-24. The general organization of an MQ queuing network using routing tables and aliases.

اسلاید 33: Tanenbaum & Van Steen, Distributed Systems: Principles and Paradigms, 2e, (c) 2007 Prentice-Hall, Inc. All rights reserved. 0-13-239227-5Message Transfer (2)Figure 4-25. Primitives available in the message-queuing interface.

اسلاید 34: Tanenbaum & Van Steen, Distributed Systems: Principles and Paradigms, 2e, (c) 2007 Prentice-Hall, Inc. All rights reserved. 0-13-239227-5Data StreamFigure 4-26. A general architecture for streaming stored multimedia data over a network.

اسلاید 35: Tanenbaum & Van Steen, Distributed Systems: Principles and Paradigms, 2e, (c) 2007 Prentice-Hall, Inc. All rights reserved. 0-13-239227-5Streams and Quality of ServiceProperties for Quality of Service:The required bit rate at which data should be transported.The maximum delay until a session has been set up The maximum end-to-end delay .The maximum delay variance, or jitter.The maximum round-trip delay.

اسلاید 36: Tanenbaum & Van Steen, Distributed Systems: Principles and Paradigms, 2e, (c) 2007 Prentice-Hall, Inc. All rights reserved. 0-13-239227-5Enforcing QoS (1)Figure 4-27. Using a buffer to reduce jitter.

اسلاید 37: Tanenbaum & Van Steen, Distributed Systems: Principles and Paradigms, 2e, (c) 2007 Prentice-Hall, Inc. All rights reserved. 0-13-239227-5Enforcing QoS (2)Figure 4-28. The effect of packet loss in (a) non interleaved transmission and (b) interleaved transmission.

اسلاید 38: Tanenbaum & Van Steen, Distributed Systems: Principles and Paradigms, 2e, (c) 2007 Prentice-Hall, Inc. All rights reserved. 0-13-239227-5Synchronization Mechanisms (1)Figure 4-29. The principle of explicit synchronization on the level data units.

اسلاید 39: Tanenbaum & Van Steen, Distributed Systems: Principles and Paradigms, 2e, (c) 2007 Prentice-Hall, Inc. All rights reserved. 0-13-239227-5Synchronization Mechanisms (2)Figure 4-30. The principle of synchronization as supported by high-level interfaces.

اسلاید 40: Tanenbaum & Van Steen, Distributed Systems: Principles and Paradigms, 2e, (c) 2007 Prentice-Hall, Inc. All rights reserved. 0-13-239227-5Overlay ConstructionFigure 4-31. The relation between links in an overlay and actual network-level routes.

اسلاید 41: Tanenbaum & Van Steen, Distributed Systems: Principles and Paradigms, 2e, (c) 2007 Prentice-Hall, Inc. All rights reserved. 0-13-239227-5Information Dissemination Models (1)Anti-entropy propagation modelNode P picks another node Q at randomSubsequently exchanges updates with QApproaches to exchanging updatesP only pushes its own updates to QP only pulls in new updates from QP and Q send updates to each other

اسلاید 42: Tanenbaum & Van Steen, Distributed Systems: Principles and Paradigms, 2e, (c) 2007 Prentice-Hall, Inc. All rights reserved. 0-13-239227-5Information Dissemination Models (2)Figure 4-32. The relation between the fraction s of update-ignorant nodes and the parameter k in pure gossiping. The graph displays ln(s) as a function of k.