1. Comparing Hybrid Peer-Peer Systems Beverly Yang Hector Garcia-Molina Stanford University Presented by Kalyan Boggavarapu

2. Different Modals [1]

3. Hybrid modal[1]

4. ► Eg: Napster ► Currently we study: OpenNap ► New issues: IR in P2P, co- operative web caching ► Modeling peer-peer systems [1]  Query modeling,  performance modeling,  validation with real data OpenNap Query model [1] f – query “selection power” g – query popularity Correlate f and g with exponential distribution

5. Architecture ► Logins: batch & incremental ► Types of architecture (partly [1]) :  Chained – forward a query ► Large and diverse data not many servers. ► Dis: expensive if many servers have to satisfy the query  Full replication – make a copy of indexes on every server. ► Dis: login information must be sent to every server  Hash – holds subset of index of words ► Bandwidth consumption would be more.  Unchained- Napster ► High data redundancy, Many servers ► Dis: restricted access to files, they cannot see the user files in other systems. Query model assumption [1]: Most popular query has the largest selection power. Assumptions for the experiment [1]: Servers are connected via LAN Users and servers are connected via same LAN network Experimentation: Hybrid architecture, OpenNap

6. Comparing P2P systems Conclusions: [1] Incremental login scales better than batch login Unchained architecture results in lower number of results returned Hash architecture is resource intensive Full replication works well when result sets are large Chained architecture is well-suited for music-sharing, but suffers from poor query performance References: [1] http://db.uwaterloo.ca/~tozsu/courses/cs856/prese ntations/jinxiao.pdf http://db.uwaterloo.ca/~tozsu/courses/cs856/prese ntations/jinxiao.pdf