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Message and Stream Oriented Communication
The document discusses communication methods in distributed systems, highlighting message-oriented and stream-oriented communication. It defines persistent vs. transient and asynchronous vs. synchronous communication, detailing their types and applications such as message queuing and pub/sub networks. Additionally, it addresses the architectures and challenges associated with these communication paradigms, including quality of service in stream-based communication.
Message and Stream Oriented Communication
- 1. Message & Stream OrientedCommunication CS4262 Distributed Systems Dilum Bandara Dilum.Bandara@uom.lk Some slides extracted from Dr. Srinath Perera & Dr. Rajkumar Buyya’s Presentation Deck
- 2. Outline Message orientedcommunication Event queues Pub/sub networks MPI Stream-based communication Multicast communication 2
- 3. Definitions – Persistent vs.Transient Communication Persistent communication Message submitted for transmission is stored by communication system for as long as it takes to deliver it to receiver e.g., e-mail, SMS Not necessary for sender to continue execution after submitting a message Not necessary for receiver to be executing at the time message submission Transient communication Message is stored by communication system only as long as sending & receiving applications are executing e.g., transport-level communication services (store-and-forward router) Receiver needs to be there when a message is received 3
- 4. Definitions – Asynchronousvs. Synchronous Communication Asynchronous communication Sender continues immediately after it has submitted its message for transmission Message may be stored, in a local buffer at sending host or at an intermediate communication server Synchronous communication Sender is blocked until its message is stored in a local buffer at receiving host or actually delivered to receiver Strongest form – Sender blocked until receiver has processed message 4
- 5. Types of Communication 5 a)Persistent asynchronous communication (e.g., e-mail) b) Persistent synchronous communication Source: A.S. Tanenbaum & M.V. Steen, Distributed Systems: Principles and Paradigms
- 6. Types of Communication(Cont.) 6 c) Transient asynchronous communication (e.g., UDP) d) Receipt-based transient synchronous communication Source: A.S. Tanenbaum & M.V. Steen, Distributed Systems: Principles and Paradigms
- 7. Types of Communication(Cont.) 7 e) Delivery-based transient synchronous communication f) Response-based transient synchronous communication Source: A.S. Tanenbaum & M.V. Steen, Distributed Systems: Principles and Paradigms
- 8. Types of Communication(Cont.) 1. Persistent, asynchronous communication Messages are persistently stored in local host buffer, or at an intermediate communication server e.g., e-mail 2. Persistent, synchronous communication Messages can be persistently stored only at receiving host Weaker form of synchronous communication It isn’t necessary for receiving application to be executing 8
- 9. Types of Communication(Cont.) 3. Transient, asynchronous communication Messages is temporarily stored in a local buffer & sender immediately continues e.g., UDP, RPC fire & forget 4. Transient, synchronous communication I. Weakest form Receipt-based, transient, synchronous communication Sender is blocked until message is stored in a local buffer of receiving host e.g., Asynchronous RPC delivery part (send with Ack) 9
- 10. Types of Communication(Cont.) II. Weaker form Delivery-based, transient, synchronous communication e.g., Asynchronous RPC delivery part (Send with Ack) III. Strongest form Response-based, transient, synchronous communication e.g., RPC & RMI 10
- 11. Message-Oriented Communication Message-orientedtransient communication Transport-level sockets Message-Passing Interface (MPI) Message transfer latency milliseconds to seconds Message-oriented persistent communication Message-queuing systems or Message-Oriented Middleware (MOM) Provide intermediate-term storage capacity for messages Doesn’t requiring either sender or receiver to be active during message transmission Message transfer latency seconds to minutes 11
- 12. Message-Queuing Model Applicationscommunicate by inserting messages into a series of queues Loosely-coupled communication Sender is given guarantee that its message will eventually be inserted in recipient’s queue No guarantee on timing, or message will actually be read 12 Source: http://msdn.microsoft.com/en- us/library/windows/desktop/ms699870% 28v=vs.85%29.aspx
- 13. Message-Queuing Model Combinations 13 Loosely-coupled communicationsusing Queues. Sender & receiver can execute completely independent of each other. Source: A.S. Tanenbaum & M.V. Steen, Distributed Systems: Principles and Paradigms
- 14. Message-Queuing Interface Basicinterface to a queue in a message- queuing system 14 Primitive Meaning Put Append a message to a specified queue Get Block until the specified queue is nonempty, & remove first message Poll Check a specified queue for messages, & remove first message. Never block Notify Install a handler to be called when a message is put into specified queue
- 15. Architecture of aTypical Message- Queuing System With Routers 15 Source: http://csis.pace.edu/~marchese/SE765/L7/L7.htm
- 16. Message Queue Applications Amazon Simple Queue Service (Amazon SQS) Decouple components of a cloud application Can transmit any volume of data, at any level of throughput, without losing messages or requiring other services to be always available 16 Source: http://docs.aws.amazon.com/AutoScaling/latest/DeveloperGuide/as-using-sqs-queue.html
- 17. Message Queue Applications(Cont.) Java Message Service (JMS) queues Based on Java Enterprise Edition (JEE) Loosely coupled, reliable, & asynchronous Other applications E-mail Workflow & Groupware Batch processing Job queues Stream/complex-event processing 17
- 18. Pub/Sub Networks Publisherspublish messages Usually to a topic Subscribers may express interest for a subset of messages Pub/Sub system makes sure interested parties get corresponding messages 80-90% implementations are topic based Content based is hard 18 Source: http://msdn.microsoft.com/en- us/library/ff649664.aspx
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- 20. Eventing in Pub/Sub Decouple Time – both parties need not be online same time Space – don’t know each other’s addresses Synchronization – don’t have to wait for each other Models Event producer Event consumer Event producer Broker Event consumer Actually it’s Event producer Event Bus Notifier Event bus can be 1+ nodes Decoupling makes it is hard to debug 20
- 21. Pub/Sub Brokers RSSfeeds Apache ActiveMQ, Qpid OGCE WS-Messenger For web services WSO2 Event Server Microsoft BizTalk Server Distributed brokers Narada Broker (www.naradabrokering.org) Whihdum (http://code.google.com/p/wihidum/) 21
- 22. Message Brokers Applicationsneed to understand messages they receive Options Standard message formats Not suitable as message-queuing applications typically operate at a higher level of abstraction Convert messages using a Message Broker Convert incoming messages to a format that can be understood by destination application 22
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- 24. Message Broker Architecture 24 Source:A.S. Tanenbaum & M.V. Steen, Distributed Systems: Principles and Paradigms
- 25. Message Bus A.k.a.Enterprise Service Bus (ESB) Tasks Monitor & control routing of message exchange between services Resolve contention between communicating service components Control deployment & versioning of services Marshal use of redundant services 25 Source: http://msdn.microsoft.com/en-us/library/ff647328.aspx
- 26. Complex Event ProcessingSystem 26
- 27. WSO2 Siddhi CEPArchitecture 27 Source: S. Suhothayan et al., “Siddhi: A Second Look at Complex Event Processing Architectures”, Nov. 2011
- 28. Siddhi Pipeline Architecture 28 Source:S. Suhothayan et al., “Siddhi: A Second Look at Complex Event Processing Architectures”, Nov. 2011
- 29. Message-Passing Interface (MPI) Designed for communication among parallel applications Primarily used in HPC systems with high-speed interconnection networks Provides an interface with advanced features such as different forms of buffering & synchronization Provides hardware independence Supports many types/forms of communication Algorithm/application specific performance optimization 29
- 30. MPI Operations 30 Source: http://www.broadinstitute.org/gatk/about/#high-performance Source:http://mpitutorial.com/mpi-reduce-and-allreduce/
- 31. MPI_Allreduce 31 Global sum followed bydistribution of result Source: Peter Pacheco, "An Introduction to Parallel Programming"
- 32. Butterfly-Structured Global Sum 32 Source:Peter Pacheco, "An Introduction to Parallel Programming"
- 33. MPI Primitives 33 Primitive Meaning MPI_bsendAppend outgoing message to local send buffer. MPI_send Send a message & wait until copied to local or remote buffer. MPI_ssend Send a message & wait until receipt starts. MPI_sendrecv Send a message & wait for reply. MPI_isend Pass reference to outgoing message, and continue. MPI_issend Pass reference to outgoing message, & wait until receipt starts. MPI_recv Receive a message; block if there is none. MPI_irecv Check if there is an incoming message, but do not block.
- 34. Stream Oriented Communication Continuous streams of data e.g., real media stream Modes Asynchronous – no time limit Synchronous – max time limit Isochronous – both max & lower limit Simple stream – One type of streams Complex stream – Many streams e.g., movie with video, 2 audio, & subtitles QoS – bit rate, delay, jitter, etc. Enforcing QoS is a main challenge 34
- 35. Streams (Cont.) EnforcingQOS Mark packets as high priority Use buffers to reduce jitter (play from buffer) 35Source: T. Banka et al., “An architecture and a programming interface for application-aware data dissemination using overlay networks,” COMSWARE 2007
- 36. Streams (Cont.) Streamsynchronization Read alternatively Control interface to control rates Distribution – merge at sender 36
- 37. Multicast Communication Networklevel – IP multicast Very efficient within LAN No global routing support Application level Main challenge is to setup a path Options Tree based Mesh based Can recover from failures Often used in parallel computing clusters Group communication Ordered reliable multicast 37
- 38. Tree-Push & Mesh-Pull 38 Source: J.Liu et al., "Opportunities and challenges of peer-to-peer internet video broadcast,” 2008. X. Zhang et al., "CoolStreaming/DONet: a data-driven overlay network for efficient live media streaming," INFOCOM 2005.