SKR 5302: Advanced Distributed Computing

9.9. Peer-to-Peer Networks: KaAzA

Peer-to-Peer Networks: KaAzA

KaZaA history

• 2001: created by Dutch company (Kazaa BV)
• Single network called FastTrack used by other clients as well
• Eventually the protocol changed so other clients could no longer talk to it

Smart query flooding

• Join: on start, the client contacts a super-node (and may later become one)
• Publish: client sends list of files to its super-node
• Search: send query to super-node, and the super-nodes flood queries among themselves
• Fetch: get file directly from peer(s); can fetch from multiple peers at once

KaZaA: Exploiting Heterogeneity

• Each peer is either a group leader or assigned to a group leader
  • TCP connection between peer and its group leader
  • TCP connections between some pairs of group leaders
• Group leader tracks the content in  all its children
  
  

  

KaZaA: Motivation for Super-Nodes

• Query consolidation
  • Many connected nodes may have only a few files
  • Propagating query to a sub-node may take more time than for the super-node to answer itself
• Stability
  • Super-node selection favors nodes with high up-time
  • How long you’ve been on is a good predictor of how long you’ll be around in the future