1. CS-495 Distributed Systems Fabián E. Bustamante, Winter 2004 Communication Networking RPC and Relatives Distributed Objects Message- & Stream-Oriented Communication

2. CS-495 Distributed Systems Layered Protocols Low-level layers Transport layer Application layer Middleware layer

3. CS-495 Distributed Systems Layers, interfaces, and protocols in the OSI model Basic Networking Model

4. CS-495 Distributed Systems Low-Level Layers Physical layer: contains the specification and implementation of bits, and their transmission between sender and receiver Data link layer: prescribes the transmission of a series of bits into a frame to allow for error and flow control Network layer: describes how packets in a network of computers are to be routed

5. CS-495 Distributed Systems Transport Layer Important: the transport layer provides the actual communication facilities for most distributed systems Standard Internet Protocols: TCP: connection-oriented, reliable, stream- oriented communication UDP: unreliable (best-effort) datagram communication

6. CS-495 Distributed Systems Client-Server TCP TCP for transactions (T/TCP): A transport protocol aimed to support client-server interaction

7. CS-495 Distributed Systems Application Layer Observation: Many application protocols are directly implemented on top of TP, doing a lot of app- independent work NewsFTPWWW TransferNNTPFTPHTTP NamingNewsgroupHost + pathURL DistributionPushPull ReplicationFloodingCaching + DNS tricks SecurityNone (PGP)Username + password

8. CS-495 Distributed Systems Middleware Layer Observation: Middleware is invented to provide common protocols and services that can be used by many different applications A rich set of communication protocols to allow different apps. to communicate Marshaling and unmarshaling of data, necessary for integrated systems Naming protocols, so that different apps. can easily share resources Security protocols, to allow different apps. to communicate in a secure way Scaling mechanisms, such as support for replication and caching Note: what remains are truly application-specific protocols

9. CS-495 Distributed Systems Middleware Protocols An adapted reference model for networked communication.

10. CS-495 Distributed Systems Papers Presented G. Eisenhauer, F. E. Bustamante and K. Schwan, Native Data Representation: An Efficient Wire Format for High-Performance Computing, IEEE Transaction on Parallel and Distributed Systems, 13 (12), pp 1234-1246, 2002. (Tuesday 1/13 - presented by Stefan Birrer)Native Data Representation: An Efficient Wire Format for High-Performance Computing, A. D. Birrell and B. J. Nelson, Implementing Remote Procedure Calls, ACM Transaction on Computer Systems, 2(1), Feb. 1984, pp 271-290. (Tuesday 1/13 - presented by James Newell)Implementing Remote Procedure Calls M. D. Schroeder and M. Burrows Performance of the Firefly RPC, in Proc. of the 12th Symposium on Operating System Principles, 1989. (Thursday 1/15 - presented by Stefan Birrer)Performance of the Firefly RPC G. Banaver, T. Chandra, R. Strom, D. Sturman, A Case for Message Oriented Middleware, in Proc. 13th International Symposium on Distributed Computing (DISC) (invited lecture), Sep. 1999, pp 1-18. (Thursday 1/15 - presented by Ashish Gupta)A Case for Message Oriented Middleware

11. CS-495 Distributed Systems Implementing RPC A. D. Birrell and B. J. Nelson – 1984 Presented by: James Newell

12. CS-495 Distributed Systems