Beyond Napster: An Overview of PeertoPeer Systems and Applications

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Beyond Napster An Overview of Peer-to-Peer
Systems and Applications

• Sami Rollins

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What is Peer-to-Peer (P2P)?
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Introduction

• Motivation a vision of the future
• A taxonomy of P2P systems
• Three common implementations
• Mobile P2P

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Motivation
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What is a peer?

• an entity with capabilities similar to other
  entities in the system.

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The Web Model

• Contact a server and download a web page
• Server has all the resources and capabilities
• Butclient devices becoming more powerful and
  well-connected

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The P2P Model

• A peers resources are similar to the resources
  of the other participants
• P2P peers communicating directly with other
  peers and sharing resources

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P2P System Taxonomy
P2P Systems and Applications
Data-centric eDonkey Gnutella
Network-centric Akamai Bittorrent
User-centric IM Skype
Computation-centric SETI_at_home/BOINC
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Computation-centricSETI_at_home/BOINC
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User-centricInstant Messaging
locatePeer
receiveMessage
locatePeer
receiveMessage
sendMessage
sendMessage
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User-centricInstant Messaging
locatePeer
locatePeer
Peer Network
receiveMessage
sendMessage
sendMessage
receiveMessage
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Network-centricContent Distribution
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Network-centricContent Distribution
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P2P Goals/Benefits

• Cost sharing
• Resource aggregation
• Improved scalability/reliability
• Increased autonomy
• Anonymity/privacy
• Dynamism

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Research Questions

• Group Management
• How do I find and connect to my peers?
• Data/Resource Location
• How do I find the resources (e.g., files) I want?

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Approaches

• Centralized
• Unstructured
• Structured (Distributed Hash Tables)

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Centralized
Bob
Alice

• Napster model
• Benefits
• Drawbacks

Jane
Judy
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Unstructured
Carl
Jane

• Gnutella model
• Benefits
• Drawbacks

Bob
Alice
Judy
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Improvements SuperPeers
Carl

• KaZaA model
• Hybrid centralized and unstructured
• Benefits
• Drawbacks

Kelly
Mary
SuperLinda
SuperWendy
SuperAdam
Jane
Judy
Alice
Bob
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Structured
001
012

• Chord, CAN, Tapestry, Pastry model
• Benefits
• Drawbacks

212 ?
212 ?
332
212
305
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P2P Challenges

• Decentralization
• Scalability and Performance
• Anonymity
• Fairness
• Dynamism
• Security

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From P2P to Mobile Computing
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Mobile Computing

• Devices frequently disconnected from each other
  and the Internet
• Devices have a limited supply of energy!

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Current Research

• Hierarchical Power Management
• Mark Corner, Jacob Sorber, Nilanjan Banerjee
  (UMass Amherst)
• Goal Combine mobile platforms with varying power
  consumption characteristics into a single
  power-efficient device
• LLAMA - Longer Lifetime Algorithms for Mobile
  Applications
• Denitsa Tilkidjieva, Maria Kazandjieva, Mark
  Corner, Nilanjan Banerjee
• Goal Employ intelligent algorithms for
  determining how much energy a mobile device can
  devote to performing background tasks

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Summary

• P2P is more than just file sharing!
• Building P2P systems and applications poses lots
  of interesting challenges

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Beyond Napster An Overview of Peer-to-Peer
Systems and Applications

• Sami Rollins

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Improvements SuperPeers

• KaZaA model
• Hybrid centralized and unstructured
• Advantages and disadvantages?