PeertoPeer P2P Recommendation Systems RS

1
Peer-to-Peer (P2P)Recommendation Systems (RS)

• A change in perspective

2
What a traditional RS is?

• Traditional RSs are big servers (usually web
  servers).
• The users can interact using a client (usually a
  web browser).
• The server collects information of users
  preferences on items through their interaction
  with the server, implicitly or explicitly
• Based on these information, the server gives
  recommendations on which items the user will like.

Keep in mind Amazon.com!
3
How traditional RS recommends?
4
How traditional RS recommends?

• Users profile is set of ratings
• Collaborative Filtering

Item1
Item2
Item1
Item1
5
User1
?
3
1
5
User2
5
5

1
User3
5
User4
5
Problems with traditional RS

• A RS needs to collect a lot of data from a lot of
  users
• Users history on amazon.com cant be used on
  barnesandnobles.com (it is in their hard disks!)
• If RS server is down (temp or forever) or not
  reachable, the user cant use the service.
• Data about many users allow to win other market
  as well and to defeat new competitors (monopoly).
• Privacy policies are defined by RS server.

6
New vision of RS
In this network, peers exchange only Users
profiles. Not Items info!
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New vision of RS exchanged info
RATINGS
(I rate Item74 as 7/10 on 23Oct02)peer31
Peer31 rates Item74 as 7/10 on 23Oct02
8
New vision of RS exchanged info
TRUSTS/REPUTATIONS
(I trust Peer12 as 0/10 on 18Aug02)peer31
Peer31 trusts Peer12 as 0/10 on 18Aug02
9
New vision of RS
IDEA Every peer can now make recommendations on
behalf of its user, using only the data it
currently has. SUB-IDEA If a peer has not
enough memory or CPU, it can ask recommendations
to other (trusted) peers.
10
New vision of RS
Every peer has the same complete information? NO

• Every peer keeps its view of the items and of
  other peers, based on
• personal interests,
• personal trust on peers,
• limitations (memory, CPU)

11
What about the Items Info?

• Items Info are NOT on peers!
• They can be on a different repository
• Centralized repository (as a website)
• Distributed file storage (as Freenet)
• but even a physical library!
• Only requirement
• items are identified by a unique id (URI)

12
GnuYork

• Scientific papers manager and alerter!
• Your unified window on research world

13
GnuYork details

• Mapping of real directories
• Bibliography (bibtex, ref, )
• ItemsScientific papers (uniquely identifiable!)
• Items repositoryCiteseer or a copy (for now)
• Ratings are implicitly inferred but can be
  modified
• Functionalities
• Recommendations!
• Publishing as HTML/XML of your work!
• It can be used with other interfaceseven
  integrated in your emacs (editor) if you like!!

14
GnuYork protocol

• Peers exchange these (signed) messages
• Opinions on papers
• Ratings (peer12 rates item278 as 7/10 explicit
  on 10oct02)
• Cocitations (peer13 cites item12, item16 in my
  paper on KM)
• Codirectoring (peer45 puts item1, item6 in dir
  know manag)
• Opinions on peers (Peer31 trusts Peer12 as 0/10
  on 14Aug02)
• Recommendation requests (please, give me a
  recommendation!)
• Protocol (mainly pull to prevent DoS)
• AskMsg ReplyMsg with hash(AskMsg)
• Every msg is signed and can be safely forwarded

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GnuYork interesting issues

• Cryptography
• Pseudonymous are used for privacy
• Every msg is signed and can be surely forwarded
• Identification of peer (with unique ID public
  key)
• Abstract communications pluggable in every p2p
  net
• First mapping on JXTA
• Reputation/Trust metrics
• In a p2p net, you cannot define behaviour!!!
• Prevent Denial of Service attacks
• Emerging protocol
• Social network analysis and visual representation
• Recommending users, community (conferences!)
  making

16
GnuYork state of project

• Defining protocol
• Defining better the functionalities
• Designing the interface
• Writing a general peers code with JXTA
• Trying cryptography in JXTA and PKIs (Public Key
  Infrastructure)
• Free software
• I used/will use a lot of free software
• Give possibility to look code to be sure there is
  no spy-ware
• Anyway, if it get used there will be people
  writing their own peers simply by
  retro-engineering communications (mojonation,
  kazaa, edonkey, )

17
GnuYork suggestions?

• How to get this used by someone?
• Papers alerter no more need to spend time in
  trying to stay up to date with a certain topic!
• Easy web publishing of your work no more need
  to edit html pages when you write a new paper!
• GnuYork does it for you!!!

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GnuYork thanks

• Thank you for your attention!