P2Pedia A Distributed Wiki Network Management and Artificial Intelligence Laboratory Carleton University Presented by: Alexander Craig May 9 th, 2011

2 Overview What is a Wiki? Distributed vs. Centralized Wikis Article Versioning Model What is P2Pedia? Versioning Path Queries and Wiki Links Trust Indicators

3 What is a Wiki? “the simplest online database that could possibly work” - Ward Cunningham

4 What is a Wiki? Wikis are edited through a web based interface using a simple markup language

5 What is a Wiki?

6 Distributed vs. Centralized Wikis Traditional wiki systems, such as Wikipedia, use a centralized architecture where all content is stored on a central server.

7 Distributed vs. Centralized Wikis In a distributed wiki system, every user of the system acts as a host, and shares a portion of the wiki data set.

8 Advantages of Distributed Wikis Reliability - No centralized point of failure Scalability - Distributed bandwidth usage and costs No centralized authority to censor content Offline operation – Users can retain read and edit access to all locally stored data even in the case of a network failure

9 Versioning Model In a traditional, centralized wiki versioning is strictly linear.

10 Versioning Model In a distributed system, articles may be modified concurrently by separate authors on separate nodes.

11 Distributed Wikis – Existing Work Existing work largely aims to present a logically centralized service over a distributed architecture.

12 Versioning Model Distributed modifications result in a tree of article versions, rather than a linear sequence

13 Versioning Model

14 Versioning Model

15 Versioning Model: Future Work P2Pedia also aims to support user assisted merging of articles. In this case, a lattice of article versions may be formed.

16 Versioning Model This distributed versioning model reflects the underlying peer to peer infrastructure of the system, and may be better suited to some domains (ex: teaching materials).

17 What is P2Pedia? A distributed wiki system implemented using the community customization options provided by the Universal Peer to Peer framework Articles are stored in an XML format, and use the Creole wiki markup open standard CREOLE – A common wiki markup

18 P2Pedia

19 P2Pedia

20 P2Pedia

21 Versioning Queries Complex queries can be performed on the version graph using the provided graph query functionality of U-P2P.

22 Versioning Queries

23 Versioning Queries

24 Versioning Queries

25 Versioning Queries

26 Versioning Queries Ex: Find all second generation edits of article “B”

27 Versioning Queries Ex: Find all sibling articles (other edits of the same parent) of article “F”

28 Versioning Queries Ex: Find all edits (descendents) of article “B”

29 Wiki Links In a centralized wiki, the latest version of an article is always authoritative.

30 Wiki Links Because no authoritative version of an article exists, wiki links are implemented as a search for all descendents.

31 Trust Indicators If article revisions are not merged into a single version, how should a user select which version of an article to view? U-P2P provides a number of resource trust indicators alongside search results to provide users with additional information.

32 Trust Indicators

33 Trust Indicators: Document Popularity Document popularity = Number of hosts serving the document Ex: Document Popularity of “A” = 3

34 Trust Indicators: Network Distance Network Distance = Number of intermediate network hops between querying node and host Ex: Average Network Distance of “A” = 0.5

35 Trust Indicators: Peer Popularity Peer popularity = Number of incoming peer connections to a specified host Ex: Peer Popularity = 2 (Assuming queried connection is outgoing)

36 Trust Indicators: Similarity Similarity = (Number of hosted articles in common) / (Total number of hosted articles) Similarity = Size({A}) / Size({A, B, C}) = 1/3

37 Conclusion P2Pedia expands on existing work by supporting a collaboration model which supports the diversification of content. Versioning is realized using document links which are queried through the distributed graph query capabilities of U-P2P. General trust indicators are introduced to allow users to evaluate the quality of content.

38 P2Pedia Live Demo: Questions?

39 References [1] “Wikipedia,” Accessed May 4 th, [2] “Wiktionary,” Accessed May 5 th, [3] “Lyric Wiki,” Accessed May 5 th, [4] “UniWiki,” Accessed May 5 th, [5] “Wooki,” Accessed May 5 th, [6] “WikiCreole,” Accessed May 5 th,