Message Passing Communication

1. Message Passing Communication Xuan Guo

2. Outline • Overview • Message Passing Communication • Basic Communication Primitives • Message synchronization and buffering • Pipe and socket APIs • Secure sockets • Group communication and multicast • Latest Relevant Research -- SOAP • Future Work • Reference

3. Overview • What is Message Passing Communication? • A paradigm of communication where messages are sent from a sender to one or more recipients (Processes, Objects). • Message • Collection of typed data objects • Structures and interpretations are defined by peer applications • Major issues • Direct or indirect addressing • Blocking or non-blocking communication • Reliable or unreliable communication • Buffered or un-buffered communication

4. Basic Communication Primitives • Communication primitives: • send(destination, message) • receive(source, message) • channel naming = process name, link, mailbox, port • Direct communication: symmetric/asymmetric process naming, link • Indirect communication: many-to-many mailbox, many-to-one port

5. Direct Send/Receive Communication Primitives Symmetric Process Name Asymmetric Process Name Links

6. mailbox mailbox mailbox Indirect Send/Receive Communication Primitives Multipath Communication Multipoint Communication

7. Message Synchronization and Buffering • Message Synchronization Stages Source Kernel DestinationKernel Sender Network Receiver 1 2 message 3 4 8 7 ack 6 5 • Non-blocking send: 1+8 (Asynchronous send) • Blocking send: 1+2+7+8 (Synchronous send) • Reliable blocking send: 1+2+3+6+7+8 (Synchronous send) • Explicit blocking send: 1+2+3+4+5+6+7+8 (Synchronous send) • Request and reply: `1-4, service, 5-8 (Synchronous send) (Client/Server)

8. Message passing API • Pipe: A FIFO byte-stream unidirectional link for related processes (set up at process invocation) • Socket: A logical communication endpoint for communication between autonomous domains (bound to physical communication endpoint) Ls –l | sort … write read FIFO pipe

9. Socket • A Socket is a communication end point of a communication link managed by the transport services. • A socket is created by making a socket system call. • The socket system call is also used to specify various network protocols such as Internet TCP, UDP and IP.

10. Peer processes Peer processes socket socket Logical communication endpoint(socket, LCD) Logical communication endpoint(socket, LCD) bind bind Physical communication endpoint (PCE) Physical communication endpoint (PCE) Send/recvfrom Connectionless socket communication

11. Connection oriented client/server socket communication

12. Secure Socket(I) • The goal of Secure socket layer (SSL) is to provide: • Privacyin socket communication by using symmetric cryptographic data encryption. • Integrityin socket data by using message integrity check. • Authenticityof servers and clients by using asymmetric public key cryptography

13. Secure Socket(II)

14. Group Communication & Multicast(I) • Group: a collection of processes that act together • When a message is sent to a group, all its members receive the message • Group are dynamic • Create/destroy groups  group management • A process can join or leave a group  membership management

15. Group Communication & Multicast(II) • Best-effort Multicast: The system needs only to guarantee the delivery of the multicast message to the reachable non-faulty processes. • Reliable Multicast: The multicast message should either be received by all of the servers or none of them.

16. Multicast orders(I) s 2 1 G 1 s G 2 s G 1 s s 1 G G 2 G s G 2 1 s s 1 1 G 1 G 2 s G 2 s 2 2

17. Multicast orders(II) • FIFO order: Multicast messages from a single source are delivered in the order that they were sent. • Causal order: Causally related messages from multiple sources are delivered in their causal order. • Total order: all messages multicast to a group are delivered to all members of group in the same order. A reliable and total order multicast is called an atomic multicast.

18. Latest Relevant Research -- SOAP • The Simple Object Access Protocol (SOAP) is an XML based protocol that is widely used over the Internet as it supports interoperability by establishing access among Web servers and clients from the same or different platforms. • SOAP was designed to be a simple message passing protocol.

19. SOAP structure

20. SOAP message exchanges are quite elaborate; • Packet Sizes • Latency • This problem has been investigated on two levels: • i) SOAP compression, to reduce message size prior to transmission; • ii) SOAP multicasting, to optimize SOAP network traffic.

21. 2011: Tekli, Joe; Damiani, Ernesto; Chbeir, Richard; , "Differential SOAP Multicasting,“ The proposed method is based on the well known concept of Tree Edit Distance to reduce similar part in SOAP message. In addition, this technique exploits a dedicated differencing output format specifically designed to carry the minimum amount of diff-information.

22. Future Work • Future work will involve in researching better heuristic algorithms to further improve performance of building similarity based SOAP multicast tree. • SOAP Message Security Validation

23. References • Phan K.A. et al., Similarity-Based SOAP Multicast Protocol to Reduce Bandwidth and Latency in Web Services. IEEE TSC, 2008, 1:2(88-103) • Tekli, Joe; Damiani, Ernesto; Chbeir, Richard; , "Differential SOAP Multicasting," Web Services (ICWS), 2011 IEEE International Conference on , vol., no., pp.1-8, 4-9 July 2011 • Werner C. et al., WSDL-Driven SOAP Compression. J. of WS Research, 2005. 2(1):18-35. • Phan K.A. et al., Minimal Traffic-Constrained Similarity-Based SOAP Multicast Routing Protocol. OTM Confederated Inter. Conf., 2009. LNCS, pp. 558-576. • "SOAP Version 1.2 Part 1: Messaging Framework (Second Edition)". W3C. April 27, 2007. Retrieved 2011-02-01.

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