1. Fast Searching in Peer-to-Peer Networks Self-Organizing Parallel Search Clusters Rocky Dunlap

2. Agenda Peer-to-peer Networks Search Links/Index Links Model Parallel Search Clusters Self-Organizing Parallel Search Clusters Further Research

3. Peer-to-Peer Networks Peer = Client + Server Anyone can send/process messages Highly Distributed Highly Parallel Data-centric routing

4. P2P Networks – Two Types Unstructured “Loose” network structure Requires less control of peers (casual searching) Fault tolerance, churn Keyword searching Structured Specific network structure Distributed Hash Tables –Smart routing Guarantees: –Bounded hops –Bounded state –Ability to search entire network

5. Unstructured Searching ?

6. The Problems Query saturation – every node processes every query Query processing redundancy Slow response time from distant nodes In reality, cannot search entire network (TTL) Need a model for studying P2P networks

7. SIL Model Search Links (forwarding) Index Links (non-forwarding)

8. SIL Model ?

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20. Index links provide full coverage Searches remain inside cluster Parallel Search Clusters

21. Assumptions –Keep network essentially unstructured (keyword searching, fault tolerance) –Search rate is high –Update rate is low Limit the number of nodes that processes query Provide full (or high) coverage of network Index links allow some nodes to proxy searches for others

22. The Challenge Self-Organizing Parallel Search Clusters Decentralized Nodes only know a few neighbors Dealing with “churn” Minimal interruption of normal operations

23. Proposed Solution Existing clusters split into two new clusters Advantages –Solves origin problem (start with one cluster) –Clusters split autonomously –Automatic load balancing Three phase approach –Color –Replicate Links –Split

24. Splitting Cluster Phase 1 Coloring !

25. Splitting Cluster Phase 1 Coloring ! Color (radius = 2)

26. Splitting Cluster Phase 1 Coloring Color (radius = 2)

27. Splitting Cluster Phase 2 Replicate Links red green

28. Splitting Cluster Phase 2 Replicate Links red

29. Splitting Cluster Phase 3 Split X

30. Splitting Cluster Phase 3 Split X

31. Splitting Cluster Phase 3 Split

32. Splitting Cluster Phase 3 Split X X X X X X X X

33. Splitting Cluster Phase 3 Split

34. Splitting Cluster Phase 3 Split

35. Further Research Initiating the split Choosing the radius for coloring phase –Want two clusters of same size Overloading index links Dealing with “churn” –Nice nodes –Not-so-nice nodes Merge operation? Simulation

36. Bibliography B. F. Cooper and H. Garcia-Molina. SIL: Modeling and Measuring Scalable Peer-to-peer Search Networks. http://www- db.stanford.edu/~cooperb/pubs/searchnets.pdf, 2003.http://www- db.stanford.edu/~cooperb/pubs/searchnets.pdf B. Yang and H. Garcia-Molina. Improving Search in Peer-to-Peer Networks. http://dbpubs.stanford.edu:8090/pub/2002-28, 2002. http://dbpubs.stanford.edu:8090/pub/2002-28