1. Peer-to-Peer Networks as a Distribution and Publishing Model Jorn De Boever (june 14, 2007)

2. 2 Outline of the presentation Introduction Characteristics and Challenges of Peer-to-Peer Peer-to-Peer Applications Classification of Peer-to-Peer Architectures Peer-to-Peer Criteria and Openness Discussion: Q&A

3. 3 Introduction Mass content distribution Inefficient and costly. Commercialization of internet Mass medium. Mostly client/server. Foundation of peer-to-peer: penetration broadband internet, reliability of connections, capacity of user equipment, evolution compression technology, and etc. Increasing demand for multimedia content. Conclusion: traditional distribution models under pressure.

4. 4 Outline of the presentation Introduction Characteristics and Challenges of Peer-to-Peer Peer-to-Peer Applications Classification of Peer-to-Peer Architectures Peer-to-Peer Criteria and Openness Discussion: Q&A

5. 5 Characteristics and Challenges of Peer-to-Peer Peer-to-peer principles Sharing resources in a peer-to-peer manner Partial or full decentralization Self organizing systems depending on level of decentralization

6. 6 Characteristics and Challenges of Peer-to-Peer Peer-to-peer versus client/server Client/server: Easy to manage and control (centralized) Negative network externalities: limited scalability, expensive distribution model, danger for bottlenecks and single points of failure.

7. 7 Characteristics and Challenges of Peer-to-Peer Peer-to-peer versus client/server Peer-to-Peer: Scalability, decentralization, transient connectivity, cost efficiency, fault tolerance, self organization, resource sharing Servents  SERVer + cliENTS Positive network externalities: Additional users = additional resources Challenges: transient connectivity, security, availability of resources and scalability

8. 8 Outline of the presentation Introduction Characteristics and Challenges of Peer-to-Peer Peer-to-Peer Applications Classification of Peer-to-Peer Architectures Peer-to-Peer Criteria and Openness Discussion: Q&A

9. 9 Peer-to-Peer Applications Communication: IM and Telephony Grid computing Collaborative applications File sharing and content distribution Wireless and ubiquitous peer-to-peer

10. 10 Outline of the presentation Introduction Characteristics and Challenges of Peer-to-Peer Peer-to-Peer Applications Classification of Peer-to-Peer Architectures Peer-to-Peer Criteria and Openness Discussion: Q&A

11. 11 Classification of Peer-to-Peer Architectures Degree of decentralization Centralized Decentralized Hybrid Degree of structure Unstructured Structured CentralizedDecentralizedHybrid

12. 12 Classification of Peer-to-Peer Architectures Centralized unstructured: e.g. Napster Central directory server Search process centralized (via server) Exchange of data occurs in peer-to-peer manner BCD E A Serve r Query D ? Download

13. 13 Classification of Peer-to-Peer Architectures Pure decentralized unstructured: e.g. Gnutella 0.4 No centralized component Node functions: client, server, router, cache and search Complete self organization A B C D QH

14. 14 Classification of Peer-to-Peer Architectures Hybrid unstructured: e.g. Gnutella 0.6 Convergence: combining advantages and circumventing the drawbacks of centralized and pure decentralized systems. Introducing hierarchy in the system via super nodes.

15. 15 Classification of Peer-to-Peer Architectures Pure decentralized structured: e.g. Chord Self organizing without centralized components. Structured: resources and nodes are mapped into address space. Indexing of address space is distributed among nodes (DHT’s). Advantages: Efficient search mechanism Disadvantages: Updating routing tables causes load Keyword-based search is not supported Load balancing

16. 16 Outline of the presentation Introduction Characteristics and Challenges of Peer-to-Peer Peer-to-Peer Applications Classification of Peer-to-Peer Architectures Peer-to-Peer Criteria and Openness Discussion: Q&A

17. 17 Peer-to-Peer Criteria and Openness When is a peer-to-peer solution appropriate? Technical/business criteria Cost of ownership. Scalability. Performance.  Peer-to-peer is a bandwidth saving distribution model and not a content model. Social criteria: Critical mass Online available peers Quantitative and qualitative availability

18. 18 Peer-to-Peer Criteria and Openness When is a peer-to-peer solution appropriate? Peer-to-peer only appropriate for mass content distribution? What about small user communities? Peer-to-peer might be possible if: Peers have strong ties and similar interests. Peers are simultaneously online enough. Incentives to cooperate are provided.

19. 19 Peer-to-Peer Criteria and Openness When is a peer-to-peer solution appropriate? Peer-to-peer and openness: open content, open access. Content is free to users, distribution is expensive to content providers. Existing systems: e.g. Lionshare, Comtella, Edutella. Peer-to-peer appropriate for open initiatives if it meets peer- to-peer criteria. If peer-to-peer is successful for open projects, storage and bandwidth costs will decrease. Decreasing resource expenses reduce the barriers for open initiatives which can lead to more accessible content.

20. 20 Outline of the presentation Introduction Characteristics and Challenges of Peer-to-Peer Peer-to-Peer Applications Classification of Peer-to-Peer Architectures Peer-to-Peer Criteria and Openness Discussion: Q&A

21. 21 Discussion: Q&A Conclusions Peer-to-peer might provide solutions for some of the flaws of client/server networks. Peer-to-peer is more than file sharing. Classification based on degree of decentralization and structure. Criteria for peer-to-peer solutions. 2007: the year of the arrival of legal peer-to-peer systems?

22. 22 Questions? Jorn De Boever – jorn.deboever@soc.kuleuven.bejorn.deboever@soc.kuleuven.be