1. Distributed Multimedia Systems James Maxlow March 24 th, 2003

2. Introduction  Most multimedia is inherently time-based – the arrival time and arrival order of data packets is important  The Internet guarantees neither when transmitting data  We don’t just want interactive multimedia over our networks… we want it to be reliable and high-quality  A distributed multimedia system can come to the rescue

3. History  60s-70s: Distributed computing research with earliest networks  80s: Compact disc, personal computer explosion  80s-90s: Distributed multimedia system research (video conferencing, et al)  90s: Current prevalent paradigm (quality of service management)

4. Goal  Simplicity in and of itself: We want and need high quality, reliable, interactive multimedia  The general Internet structure is not sufficient to accomplish this  A distributed multimedia system will add protocols and architectures on top of the Internet (or LAN) to guarantee quality levels, thereby satisfying our need

5. Definitions  Bandwidth: data rate through a component  Latency: time needed for a packet to travel end to end  Loss rate: acceptable drop-frame ratio  Quality of service management: negotiation and allocation of computing resources

6. Definitions  Flow specification: explicit representation of required resources  Traffic shaping: using buffers at source and destination to smooth data flow  Admission control: allowing or denying client requests based on available resources

7. 1: Sources provide flow spec to main QOS manager through local QOS managers 2: Main QOS ready to reserve resources 3: Client send request to main QOS 4: Main QOS decides if client can be served based on available resources 5: If so, main QOS tells local QOS to allocate resources (if not, client is rejected) 6: Service begins 7: Main QOS and local QOS monitor resource usage / quality, adjust allocated resources if necessary 8: Return to step 4 if new client connects 9: Service ends, resources are freed Controller Features and Structure Client Source QOS Main QOS Transmission Line (Internet)

8. How To Use  A distributed multimedia system is a combination of source hardware, QOS manager software, and a transmission line  Can be bought as a complete, dedicated, proprietary package – very expensive!  Can be built using existing hardware and Internet / LAN connection lines… all that is needed beyond that is QOS management software – can be purchased or developed

9. Applications  Video conferencing  Live news feeds  Video-on-demand  Remote-control of exploratory robots  Remote musical collaborations  Remote surgical operations

10. Significant Points  Distributed multimedia systems exist to guarantee quality of delivery levels  Resource reservation is the key  Additional clients do not degrade system – they can be refused if resources are scarce  Quality guarantees are of paramount importance, whether used for business, entertainment, scientific or health-related applications

11. Summary  Serving multimedia requires strict resource control to maintain quality  Resources consist of bandwidth, latency, and loss rate, among others  Source components declare the resources they need in flow specifications  Quality of service managers negotiate and reserve resources to guarantee quality  Source + flow spec + QOS manage + transmission lines = distributed multimedia system

12. References  Bashandy, Ahmed, Paul, R., Baqai, S., Sedigh, S., Fahmi, H., Ghafoor, A. “A Protocol Architecture for Guaranteed Quality of Service in Collaborated Multimedia Applications.” Proceedings of the IEEE Symposium on Application -Specific Systems and Software Engineering & Technology. 1999.  Coulouris, George, Dollimore, J., Kindberg, T. Distributed Systems Concepts and Design, Third Edition. New York: Addison Wesley, 2001.  Karr, David, Rodrigues, C., Loyall, J., Schantz, R., Krishnamurthy, Y., Pyarali, I., Schmidt, D. “Application of the QuO Quality-of-Service Framework to a Distributed Video Application.” Proceedings of the International Symposium on Distributed Objects and Applications. 2001.  Loyall, Joseph, Schantz, R., Zinky, J., and Bakken, D. “Specifying and Measuring Quality of Service in Distributed Object Systems.” Proceedings of the 1st International Symposium on Object-Oriented Real-Time Distributed Computing. 1998.  Stobart, Joel. “The use of Videoconferencing as a function of distributed organization: The differences of implementation depending on scale.” Papers of the 2nd Annual Conference on Multimedia Systems, Southampton Univ., UK. 2002.  Xu, Dongyan, Nahrstedt, K., Wichadukal, D. “QoS and Contention-Aware Multi-Resource Reservation.” Cluster Computing 4, pp. 95-107. 2001.  Websites:  http://www.cse.msu.edu/icdcs/ “ICDCS 2003” http://www.cse.msu.edu/icdcs/  http://www.idms2001.org/ “iDMS 2001” http://www.idms2001.org/  http://mips2003.idms-proms.org/ “MIPS 2003” http://mips2003.idms-proms.org/  http://iwqos03.cs.berkeley.edu/ “IWQoS 2003” http://iwqos03.cs.berkeley.edu/  http://www.computer.org/computer/timeline/ “Timeline of Computing History” http://www.computer.org/computer/timeline/