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Scalable Adaptive Data Dissemination Under Heterogeneous Environment. Yan Chen, John Kubiatowicz and Ben Zhao UC Berkeley. Dissemination Tree of OceanStore. Using Application-Level Multicast for Data Dissemination. Scalability Fault-tolerance Efficiency Adaptability. Our Solutions.
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Scalable Adaptive Data Dissemination Under Heterogeneous Environment Yan Chen, John Kubiatowicz and Ben Zhao UC Berkeley
Using Application-Level Multicast for Data Dissemination • Scalability • Fault-tolerance • Efficiency • Adaptability
Our Solutions • Use Tapestry, Distributed Overlay Routing & Location Infrastructure • Randomized data structure with search locality • Insensitive to faults, and self-repairable • Ease-of-maintenance • http://www.cs.berkeley.edu/~ravenben/tapestry.pdf
Our Solutions (Cont’d) • Dedicated Infrastructure • Complemented with intelligent replica placement • Application-Level Semantics & Optimization • Dynamic transmission (selective dissemination) • Dynamic notification of updates
Dissemination Tree Construction • Client Contact Statistically Closest Server Which Has the Data Through Tapestry • Autonomous decision - Path & load piggybacked • If client unsatisfied with QoS, server dynamically replicate data close to client • Model the Replica Placement as “Minimal Set Covering” Problem • Each server covers certain subset of clients (w.r.t. certain QoS, latency, bandwidth, etc.) • Approximate the solution with greedy algorithm • Distributed load balancing
RealCast Tree Management Protocols • Bi-directional Messaging • Heartbeatmessage stream from root to clients • Refresh message from children to parent • Scalability • Each member only maintains states for direct children and parent • “Join” request can be handled by any member • Continuous Self-tuning and Auto-repair • Periodically check for better parent • Topology-aware through Wide-area Network Measurement and Monitoring Services (WNMMS)
push invalidate push update App-Level Semantics and Optimization • Selective Dissemination • Dynamic update notification • Quantitative analytic model for dynamically choosing between poll (pull everytime), push invalidate and push update based on access/update pattern and clients’ preferences to certain metrics (e.g. average latency)
Preliminary Simulation • Topology generated with GT-ITM (120 nodes) • Synthetic hot-cold pattern workload (100 objects) • Base-line is the push invalidate from Cao/Liu paper • Number of messages reduced by 10 - 20% • Average response latency reduced by 30 - 40%
Conclusions • Dissemination Tree: Large-scale Data Dissemination with App-level Multicast • Key Techniques • Use distributed location services, Tapestry • “Minimal Set Covering with Load Balancing” for replica/service placement • App-level semantics and optimization • Preliminary Results • Feasibility of the infrastructure • Flexibility and effectiveness of app-level optimization