ecs289m Spring, 2008 Online Social Network (1)

1. ecs289m Spring, 2008Online Social Network (1) S. Felix Wu Computer Science Department University of California, Davis wu@cs.ucdavis.edu http://www.cs.ucdavis.edu/~wu/

2. Online Social Network • What is a social network? • What is an online social network? • Realize and represent the human social networks “explicitly” (from “somewhat vague, fuzzy and implicit”) • Promote “OSN Applications” • Utilizing the “online” perspective to further develop the human social network Davis Social Links

3. Is this a spam? FROM:MR.CHEUNG PUI Hang Seng Bank Ltd Sai Wan Ho Branch 171 Shaukiwan Road Hong Kong. Please contact me on my personal box [puicheungcheungpui@yahoo.com] Let me start by introducing myself, Felix. I am Mr. Cheung Pui, director of operations of the Hang Seng Bank Ltd,Sai Wan Ho Branch. I have a obscured business suggestion for you. Before the U.S and Iraqi war our client Matt (Bishop) who was with the Iraqi forces and also business man made a numbered fixed deposit for 18 calendar months, with a value of Twenty Four millions Five Hundred Thousand United State Dollars only in my branch. Upon maturity several notice was sent to him,… Davis Social Links

4. This was considered a spam! Davis Social Links

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7. About ecs289m • This is a research-oriented course. • Learning via guided survey, proposal, research study, and experiments • “The process is more important than the result” -- Journaling Davis Social Links

8. The Requirement • Your electronic “research journal” • Timestamp • What did you learn from the lectures and the readings? Any reflective comments/thoughts? • What problems are you considering and why? Who you have talked to further narrow or broader the scope? • What was/is your plan (and its evolution)? Why is this plan exciting and how to justify that? • What about the execution and result? • What have you learned? Davis Social Links

9. Grading • Is the journal truthful? (I.e., is that really you who did this and that?) • Is the journal significant, not superficial, and mature at the end? • Was the recording of the journal reasonably frequent? (I.e., you made progress weekly and you need to submit and share your journal with others.) • A final presentation & interactive grading Davis Social Links

10. Examples • OSN core architecture and evaluation • Novel OSN applications • OSN data collection and analysis • OSN network development • Implementation, Theoretical Analysis, Real data analysis, Simulation Davis Social Links

11. About the Instructor • S. Felix Wu (wu@cs.ucdavis.edu, x4-7070) • Office: 3057 Kemper Hall • Office Hours: • 10:30-11:30 a.m. on Mon/Fri • by appointment • Project meeting (10:30~11:30 Wed, TBA) • I like to have another hour for the class to get together for discussion • For remote students, we will do teleconference. Davis Social Links

12. Class communication • You must have a Facebook account! • I will set up a group for you to join. • If you are not yet my FB friend, you must not be my friend until this quarter is over. • I will help you to setup DSL such that you can still communicate with me. • I will use “email” as the backup. • Header: [ecs289m s2008] Davis Social Links

13. Reading Assignments • DSL related papers • Many other papers Davis Social Links

14. Readings (1) • “Statistical mechanics of complex networks” by Albert and Barabasi, REVIEWS OF MODERN PHYSICS, Volumne 74, January 2002. • “Complex networks and decentralized search algorithms” by Kleinberg, Proceedings of the International Congress of Mathematicians, Madrid, Spain, 2006. • “Searching in a Small World” by Oskar Sandberg, Thesis. • I will put the links under the course website: • http://www.cs.ucdavis.edu/~wu/ecs289m/index.html • You don’t have to read everything, but please journal the parts you read (and which parts!). Davis Social Links

15. Your inputs are welcome!! • This is not a traditional academic graduate course. Davis Social Links

16. Davis Social Links • Routable identity versus receiver control • Trust & Reputation system in “L3” • Applications: • FIND (Future Internet Design), OSN (Facebook/Orkut/SecondLife), MANET Davis Social Links

17. Communicate: [A, D] B D A C As long as “A” knows “D’s routable identity” … Davis Social Links

18. Urgent! Please contact me! FROM:MR.CHEUNG PUI Hang Seng Bank Ltd Sai Wan Ho Branch 171 Shaukiwan Road Hong Kong. Please contact me on my personal box [puicheungcheungpui@yahoo.com] Let me start by introducing myself. I am Mr. Cheung Pui, director of operations of the Hang Seng Bank Ltd,Sai Wan Ho Branch. I have a obscured business suggestion for you. Before the U.S and Iraqi war our client Major Fadi Basem who was with the Iraqi forces and also business man made a numbered fixed deposit for 18 calendar months, with a value of Twenty Four millions Five Hundred Thousand United State Dollars only in my branch. Upon maturity several notice was sent to him,… Davis Social Links

19. Hijacked Routable Identify Davis Social Links

20. [A,D] + social context B D A C “A” has to explicitly declare if there is any social context under this communication activity with “D”! Davis Social Links

21. The same message content • “M” from Cheung Pui • “M” from Cheung Pui via IETF mailing list • “M” from Cheung Pui via Karl Levitt Davis Social Links

22. Social Context • “M” from Cheung Pui  Probably a spam • “M” from Cheung Pui via IETF mailing list  Probably not interesting • “M” from Cheung Pui via Karl Levitt  Better be more serious… Davis Social Links

23. Social Context • “M” from Cheung Pui  Probably a spam • “M” from Cheung Pui via IETF mailing list  Probably not interesting • “M” from Cheung Pui via Karl Levitt  Better be more serious… Either “M” is important, or Karl’s machine has been subverted! Davis Social Links

24. [A,D] + social context ?? B D A C “A” has to explicitly declare if there is any social context under this communication activity with “D”! But, “D” only cares if it is from “C” or not! Davis Social Links

25. Online Social Network • What is a social network? • What is an online social network? • Realize and represent the human social networks “explicitly” (from “somewhat vague, fuzzy and implicit”) • Promote “OSN Applications” • Utilizing the “online” perspective to further develop the human social network • Representation, Application, Development Davis Social Links

26. Just initially, a couple issues … • How to establish the social route? • How would “A” know about “D” (or “D’s identity”) ? • How to maintain this “reputation network”? • MessageReaper: A Feed-back Trust Control System (Spear/Lang/Lu) Davis Social Links

27. Social network analytical models • Network Mathematics (Sandberg’s talk) • Random graph model (low diameter) • Newman/Watts/Strogatz, 2002 • Small world model (high cluster coefficient) • Watts/Strogatz, 1998 • Scale-free network (node degree distribution) • Barabasi/Albert, 1999 • What is the right model for the network? • Please read “#1”. Davis Social Links

28. Search on “OSN” • How to get to from ? • The Small world model • 6 degree separation (Milgram, 1967) • “existence of a short path” • How to find the short path? (Kleinberg, 2000) Davis Social Links

29. Routing in a Small World • Common question: do short paths exist? • Algorithmic question: assuming short paths exist. How do people find them? Davis Social Links

30. Kleinberg’s Model • Kleinberg’s model: • People  points on a two dimensional grid. • “P” Grid edges (short range). • “Q”long range contacts chosen with the inverse rth-power distribution. • How to search? • [S, T] • Find the neighbor closest to T • Work well only when r=2, p=q=1 Davis Social Links

31. Kleinberg’s Model • Use only Local information, except the distance to the target. • However, what is the “global distance” in cyber space? • Yet, the assumption behind is that the “edges” depend on the “relative distance”. Davis Social Links

32. In Facebook… • How will we tell whether the relative distance between X&Y is closer than X&Z? • X, Y, Z (assuming they are all direct friends to each other) • One simple idea: “Keyword intersection” • KW(X), KW(Y), KW(Z) • 1/(#[KW(a) KW(b)] + 1) • Will this work? How about global distance? Davis Social Links

33. Kleinberg’s model • Inherently assume “routable identity” • You have to know the Target identity, and you also need to know the distance metric. • And, then the search algorithm will get to it probabilistically. • The sender/receiver interface is very simple. • Please read the papers for details. Davis Social Links

34. [A,D] + social context ?? B D A C “A” has to explicitly declare if there is any social context under this communication activity with “D”! But, “D” only cares if it is from “C” or not! Davis Social Links

35. Just initially, a couple issues … • How to establish the social route? • How would “A” know about “D” (or “D’s identity”) ? • How to maintain this “reputation network”? • MessageReaper: A Feed-back Trust Control System (Spear/Lang/Lu) Davis Social Links

36. Social Route Discovery for A2D ?? B D A C Let’s assume A doesn’t have D’s “routable identity” Or, “D” doesn’t have a global unique identity! Then, how can we do A2D? Davis Social Links

37. Finding ?? B D A C A2D, while D is McDonald’s! D would like “customers” to find the right route. “idea: keyword propagation” e.g., “McDonald’s” Davis Social Links

38. Announcing B D K: “McDonald’s” A C Hop-by-hop keyword propagation Davis Social Links

39. Announcing B D K: “McDonald’s” K: “McDonald’s” A C Hop-by-hop keyword propagation Davis Social Links

40. Announcing B D K: “McDonald’s” K: “McDonald’s” K: “McDonald’s” A C Hop-by-hop keyword propagation Davis Social Links

41. Discussion Hour • Wednesday 10:00~10:55a.m. • 1131 Kemper • For remote students • I will set up a remote teleconference # • Try this as well - 530-752-5712 Davis Social Links

42. Now Finding Q: McDonald’s B D K: “McDonald’s” K: “McDonald’s” K: “McDonald’s” A C Search Keyword: “McDonald’s” A might know D’s keyword via two channels (1) Somebody else (2) From its friends Questions: does D need an identity? Scalable? Davis Social Links

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44. Phishing is default Application Test Q: McDonald’s B D K: “McDonald’s” K: “McDonald’s” K: “McDonald’s” A C Search Keyword: “McDonald’s” Questions: is this the right Felix Wu’s? Davis Social Links

45. Application Tests • Example 1: credential-oriented • “PKI certificate” as the keyword • If you can sign or decrypt the message, you are the ONE! • Example 2: service-oriented • Service/protocol/bandwidth support • Example 3: offer-oriented • Please send me your coupons/promotions! Davis Social Links

46. “Identity” • Application identity=M=> Network identity • Network identity =R=> Network identity • Network identity =M=>Application identity • Keywords =R=> “Multiple Paths” • Application identity selection • Network route selection Davis Social Links

47. Finding Application Test Q: McDonald’s B D K: “McDonald’s” K: “McDonald’s” K: “McDonald’s” A C Search Keyword: “McDonald’s” Questions: is this the right Felix Wu’s? What is the issue here?? Davis Social Links

48. Scalability - Avoid the Flooding • As it is, every keyword will need to be propagated to all the nodes/links (but the same keyword will be propagated through the same link once possibly with different policies). • The issue: “who should receive my keywords?” Davis Social Links

49. Community-Keyword Model • A Social Peer, P, has three keyword sets: • Attributes (ATTR) • Original Keywords (OK) • Propagating Keywords (PK) Davis Social Links

50. Community-Keyword Model • Attributes (ATTR) • Keywords describing P (the social node) • Decided/configured by the owner of P • Original Keywords (OK) • Keywords announced by P (the social node) • Decide/configured by the owner of P • Each keyword is associated with a propagation policy (decided by the owner of P) • Propagating Keywords (PK) • From its own OK and other direct neighbors • Each keyword is associated with a propagation policy Davis Social Links