December 4, 2002 CDS&N Lab., ICU Dukyun Nam The implementation of video distribution application using mobile group communication ICE 798 Wireless Mobile Internet – Fall 2002 Term Project

2 Introduction  Group Communication Service [6, 11] a collection of processes forms a fault-tolerant group and cooperatively performs a distributed computation using group communication protocols that guarantee message delivery ordering (process group & group programming tools) Group membership It hides from application the internal coordination of a group Consistency of view Reliable multicast It delivers a single message to multiple receivers Atomicity Ordering  Consideration in wireless environment Unreliable communication Handoff Disconnected mode & Idle mode Disconnection is distinct from failure No long-run application in mobile Join/Leave operation is occurred frequently  Mobile Group Communication Service [10]

3 Motivation  Killer application of group communication? Replication to support fault tolerance Try to support multimedia data in this project  Multimedia data Video, Audio, Text, etc. MPEG-1 Video in this project Timeliness  Wireless environment Loss rate in wireless networks is higher than in wired networks  Group communication can provide QoS to end users

4 Background  MPEG video data [9] Consists of I frame, B frame, and P frame I (interframe), P (predicted), B (bi-directional) Priority: I > P > B MPEG Data Frames

5 Related work  Group Communication in mobile environments MobileChannel [7] Hides handoff using group communication –Using primary migration Prakash and Baldoni’s approach [13] Proximity layer –For location awareness Group Multicast [1, 5] Coordinator based approach Disconnected member : automatically recover if reconnected Existing group communication systems in WANs [3, 4, 8] Paritionable network Support split and remerging

6 Related work (cont.)  Mobile Group Communication Service [10] Designed by ICU CDS&N Lab. Underlying protocol UDP, not IP multicast MGCS Architecture

7 Design  Sample environments Source In wired networks Sink In wireless networks Loss rate is high Sample environments

8 Design (cont.)  MPEG Data Packs: collection of packets  Data delivery Pack start codePack headerPacket        End code Packet start codePacket headerPacket data Structure of MPEG data Receiver 2 Receiver 3 Receiver 1 Start Code I frames B frames P frames MPEG Sender Data delivery of MPEG frames

9 Implementation  MPEG player [12] JDK 1.3 Procedure 1) Loading and parsing of the MPEG-files 2) Reconstruction of the single frames 3) Playing of the frames as animation in a thread  Group communication protocol MGCS [10] Mpeg stream stream … Local decoding Partitioning Start pointEnd point MPEG data partitioning

10 Demonstration  MPEG video data delivery using MGCS Environments Assume high loss rate networks Use small size MPEG file Case 1 Use IP multicast B frames are lost Case 2 Use MGCS I-, B-, P-frames are delivered SourceSink IP multicast Source Sink MGCS Membership Server MSS

11 Conclusion  Video distribution application using MGCS Guarantee reliable data exchange among members in wireless networks MGCS’s errors are fixed, but not completed.  Implementation problems of MGCS Buffer management Packet fragmentation  Future work Fix bugs of MGCS Performance evaluation MGCS and video distribution application –Reliable delivery vs. playing time Test this application in the wireless test-bed

12 References [1] G. Anastasi, A. Bartoli, and F. Spadoni, “Group Multicast in Distributed Mobile Systems with Unreliable Wireless Network,” Proceedings of the 18th IEEE Symposium on Reliable Distributed Systems, pp , October [2] T. Anker, D. Dolev, and I. Keidar, “Fault Tolerant Video on Demand Services,” Proceedings of the 19th International Conference on Distributed Computing Systems, pp , June [3] Ö. Babaoğlu, R. Davoli, L.-A. Giachini, and M.G. Baker, “RELACS: A Communication Infrastructure for Constructing Reliable Applications in Large-Scale Distributed Systems,” Proceedings of the 28th Annual Hawaii International Conference on System Sciences, pp , January [4] Ö. Babaoğlu, R. Davoli,, and A. Montresor, “Group Communication in Partitionable Systems: Specification and Algorithms,” IEEE Transactions on Software Engineering, 27 (4), pp , April [5] A. Bartoli, “Group-based multicast and dynamic membership in wireless networks with incomplete spatial coverage,” ACM/Baltzer Mobile Networks and Applications, 3 (2), pp , June [6] K.P. Birman, “The Process Group Approach to Reliable Distributed Computing,” Communications of the ACM, 36 (12), pp , December [7] K. Cho and K.P. Birman, “A Group Communication Architecture for Mobile Computing,” Proceedings of Workshop on Mobile Computing Systems and Applications, pp , December [8] D. Dolev and D. Malki, “The Transis Approach to High Availability Cluster Communication,” Communications of the ACM, 39 (4), pp , April [9] D.L. Gall, “MPEG: A video compression standard for multimedia applications,” Communications of the ACM, 34(4), pp , [10] B. Kim, D. Lee, and D. Nam, “Scalable Group Membership Service for Mobile Internet," Proceedings of the Seventh IEEE International Workshop on Object-oriented Real-time Dependable Systems (WORDS 2002), pp , January [11] L.E. Moser, Y. Amir, P.M. Melliar-Smith, and D.A. Agarwal, “Extended Virtual Synchrony,” Proceedings of the 14th International Conference on Distributed Computing Systems, pp , June [12] MPEG-1 Java Player site, [13] R. Prakash and R. Baldoni, “Architecture for Group Communication in Mobile Systems,” Proceedings of the 17th IEEE Symposium on Reliable Distributed Systems, pp , October 1998.