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Chapter 20: Social Service Selection

Chapter 20: Social Service Selection. Service-Oriented Computing: Semantics, Processes, Agents – Munindar P. Singh and Michael N. Huhns, Wiley, 2005. Reputation Mechanisms. The agency (e.g., eBay) is the authority that Authenticates users Records, aggregates, and reveals ratings

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Chapter 20: Social Service Selection

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  1. Chapter 20:Social Service Selection Service-Oriented Computing: Semantics, Processes, Agents– Munindar P. Singh and Michael N. Huhns, Wiley, 2005

  2. Reputation Mechanisms The agency (e.g., eBay) is the authority that • Authenticates users • Records, aggregates, and reveals ratings • Provides the conceptual schema for • How to capture ratings (typically a number and text) • How to aggregate them • How to decay them over time • Owns ratings – controls how it can be used Service-Oriented Computing: Semantics, Processes, Agents - Munindar Singh and Michael Huhns

  3. Recommender Techniques • Content-based filtering • Social information filtering • Collaborative filtering • Model-based approaches • Memory-based approaches • Use ratings directly to recommend Service-Oriented Computing: Semantics, Processes, Agents - Munindar Singh and Michael Huhns

  4. Recommending Products vs. Services • Products (by a product vendor) • The recommender is the provider • Votes are known to recommender • Votes are given prior to usage (buying) • Repetition is less likely (buy the same book) • Services (by a service registry) • The recommender is not the provider • Votes are not necessarily known to recommender • Votes are given after usage • Repetition can occur but not known to registry Service-Oriented Computing: Semantics, Processes, Agents - Munindar Singh and Michael Huhns

  5. Referrals

  6. Social Networks and Referral Chains • Referral chains provide: • Way to judge the quality of an expert's advice • Reason for the expert to respond in a trustworthy manner Social networks induce referral chains in which an individual may participate • As the chains get longer • The trustworthiness of a recommendation decreases • The effort to find experts increases • Therefore, shorter chains are better Service-Oriented Computing: Semantics, Processes, Agents - Munindar Singh and Michael Huhns

  7. Service Communities • Each principal • Provides services to others • Exploits services provided by others • Has a reputation • The agents assist their users and other agents in • Evaluating the services and referrals provided by others • Maintaining contact lists • Deciding whom to contact for a service Service-Oriented Computing: Semantics, Processes, Agents - Munindar Singh and Michael Huhns

  8. Distributed Treatment of Referrals Receive request Ask Model asker Follow referrals Respond Use Rate; update Service-Oriented Computing: Semantics, Processes, Agents - Munindar Singh and Michael Huhns

  9. Model for Referrals • Each agent has • An interest (services sought) • An expertise (services provided) • Models of acquaintances • Acquaintance models are built autonomously and represent • Acquaintances’ expertise (ability to provide good service along a set of dimensions) • Sociability (ability to provide accurate referrals) Service-Oriented Computing: Semantics, Processes, Agents - Munindar Singh and Michael Huhns

  10. Reputation Buildup and Collapse A participant who begins to misbehave is detected Service-Oriented Computing: Semantics, Processes, Agents - Munindar Singh and Michael Huhns

  11. Social Mechanism for trust

  12. Small World Phenomenon Milgram (1967): two individuals chosen at random in the U.S.A. are linked by a chain of 6 or fewer first-name acquaintances (empirical observation) • Six degrees of separation • Erdös numbers • Diameter of the connected Web: 20 Service-Oriented Computing: Semantics, Processes, Agents - Munindar Singh and Michael Huhns

  13. Social Mechanism of trust • Using probabilistic models for reasoning with beliefs • Bayesian model • Primarily using conditional probabilities • Dempster-Shafer model • Model that explicitly deals with belief values for various hypothesis Service-Oriented Computing: Semantics, Processes, Agents - Munindar Singh and Michael Huhns

  14. Identity & Reputation • Approaches to service selections based on reputations – face the threat that such reputations can be forged • Also, vendors can change names easily – “cheap pseudonyms” Service-Oriented Computing: Semantics, Processes, Agents - Munindar Singh and Michael Huhns

  15. Highlights of this Chapter • Reputation Mechanisms • Recommender Techniques • Referrals • Social Mechanism for Trust • Identity Service-Oriented Computing: Semantics, Processes, Agents - Munindar Singh and Michael Huhns

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