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Understanding Agents in Service-Oriented Computing: Concepts and Applications

This chapter delves into the integration of agents within service-oriented computing, explaining their characteristics, environments, and the significance of agent abstractions. It covers the distinct features of computational agents, including autonomy, communication, and adaptability, highlighting their roles in dynamic system environments. The concepts of multi-agent systems (MAS), rules for composition, and the application of agent-based models in modern computing are also explored. This knowledge is essential for leveraging agents in various domains, including e-commerce, logistics, and team problem-solving.

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Understanding Agents in Service-Oriented Computing: Concepts and Applications

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  1. Chapter 15:Agents Service-Oriented Computing: Semantics, Processes, Agents– Munindar P. Singh and Michael N. Huhns, Wiley, 2005

  2. Highlights of this Chapter • Agents Introduced • Agent Environments • Agent Descriptions • Abstractions for Composition • Describing Compositions • Composition as Planning • Rules Service-Oriented Computing: Semantics, Processes, Agents - Munindar Singh and Michael Huhns

  3. Agents and MAS for SOC Why the interest in agents for Web services? • Need for autonomy, heterogeneity, dynamism Unlike conventional services, agents • Know about themselves, their users, and their competitors • Use and reconcile ontologies • Are proactive and communicative • Are autonomous about their commitments • Can be cooperative Service-Oriented Computing: Semantics, Processes, Agents - Munindar Singh and Michael Huhns

  4. What is an Agent? • The term agent in computing covers a wide range of behavior and functionality. • In general, an agent is an active computational entity • with a persistent identity • that can perceive, reason about, and initiate activities in its environment • that can communicate (with other agents) and change their behavior based on others • These features make agents a worthwhile metaphor in computing Service-Oriented Computing: Semantics, Processes, Agents - Munindar Singh and Michael Huhns

  5. Dimensions of MAS: Agent Adaptivity (the ability of an agent to learn): Autonomy: Interactions: Sociability (awareness): Fixed Teachable Autodidactic Controlled Interdependent Independent Simple Complex Autistic Committing Collaborative Service-Oriented Computing: Semantics, Processes, Agents - Munindar Singh and Michael Huhns

  6. Agent Abstractions/1 The traditional abstractions are from AI and are mentalistic beliefs: agent’s representation of the world knowledge: (usually) true beliefs desires: preferred states of the world goals: consistent desires intentions: goals adopted for action Service-Oriented Computing: Semantics, Processes, Agents - Munindar Singh and Michael Huhns

  7. Agent Abstractions/2 • The agent-specific abstractions are inherently interactional • social: about collections of agents • organizational: about teams and groups • ethical: about right and wrong actions • legal: about contracts and compliance Service-Oriented Computing: Semantics, Processes, Agents - Munindar Singh and Michael Huhns

  8. Agent Abstractions/3 Agents, when properly understood • lead naturally to multiagent systems • provide a means to capture the fundamental abstractions that apply in all major applications and which are otherwise ignored by system builders Service-Oriented Computing: Semantics, Processes, Agents - Munindar Singh and Michael Huhns

  9. Agents versus AI Service-Oriented Computing: Semantics, Processes, Agents - Munindar Singh and Michael Huhns

  10. How to Apply the Abstractions Consider how the components of a large and dynamic software system in a practical situation • Dynamism => autonomy • Openness and compliance => ability to enter into and obey contracts • Trustworthiness => ethical behavior Service-Oriented Computing: Semantics, Processes, Agents - Munindar Singh and Michael Huhns

  11. Why Do These Abstractions Matter? • Because of modern applications that demand going beyond traditional metaphors and models • Virtual enterprises: manufacturing supply chains, autonomous logistics, • Electronic commerce: utility management • Communityware: social user interfaces • Problem-solving by teams Service-Oriented Computing: Semantics, Processes, Agents - Munindar Singh and Michael Huhns

  12. Agent Environments • Communication Infrastructure • Shared memory (blackboard) • Connected or Connectionless (email) • Point-to-Point, Multicast, or Broadcast • Directory Service • Communication Protocol • FIPA ACL • HTTP and HTML • RMI, OLE, CORBA, DCOM, etc. • Interaction Protocol, i.e, conversations such as contracting • Mediation Services • Security Services (timestamps/authentication/currency) • Remittance Services • Operations Support (archiving/billing/redundancy/restoration/accounting) Service-Oriented Computing: Semantics, Processes, Agents - Munindar Singh and Michael Huhns

  13. A Reactive Agent in an Environment Environment e; RuleSet r; while (true) { state = senseEnvironment(e); a = chooseAction(state, r); e.applyAction(a); } Service-Oriented Computing: Semantics, Processes, Agents - Munindar Singh and Michael Huhns

  14. Characteristics of Agent Environments • Observability: can all aspects relative to actions be sensed? • Determinism: is next state completely determined by current state + agent’s action? • History Freedom: does action choice depend on previous episodes or just current episode? • Dynamism: can environment change while agent is deliberating? • Continuity: do the agent actions, environment state variables, and time points have a continuous range of values? • Multiagent: is the agent aware of others that can affect the environment? Service-Oriented Computing: Semantics, Processes, Agents - Munindar Singh and Michael Huhns

  15. Agent Architectures • Logic-Based • Reactive • Belief-Desire-Intention (BDI) • Layered Architecture Service-Oriented Computing: Semantics, Processes, Agents - Munindar Singh and Michael Huhns

  16. Logic Based Agents • Decision making is realized through logical deduction • View the agents as particular type of knowledge based system • Contains an explicitly represented symbolic model of the world • Takes decisions via symbolic reasoning • Problems: • Translating the real world into an accurate adequate symbolic description, in real-time • How to represent information symbolically about complex real-world entities Service-Oriented Computing: Semantics, Processes, Agents - Munindar Singh and Michael Huhns

  17. A Rational Agent Rationality depends on... • The performance measure for success • What the agent has perceived so far • What the agent knows about the environment • The actions the agent can perform An ideal rational agent:for each possible percept sequence, it acts to maximize its expected utility, on the basis of its knowledge and the evidence from the percept sequence Service-Oriented Computing: Semantics, Processes, Agents - Munindar Singh and Michael Huhns

  18. Cognitive Architecture for an Agent Service-Oriented Computing: Semantics, Processes, Agents - Munindar Singh and Michael Huhns

  19. Reactive Architecture • Does not rely on symbol manipulation, e.g., Rodney Brooks’ subsumption architecture • Intelligent behavior can be generated without explicit representations proposed by symbolic AI • Intelligent behavior can be generated without explicit abstract reasoning • Intelligence is an emergent property of certain complex systems Service-Oriented Computing: Semantics, Processes, Agents - Munindar Singh and Michael Huhns

  20. Subsumption Architecture • A hierarchy of task-accomplishing behaviors • Each behavior is a rather simple rule-like structure • Each behavior competes with others to exercise control over the agent • Lower layers present more primitive kinds of behavior • In terms of computation, the resulting systems are extremely simple Service-Oriented Computing: Semantics, Processes, Agents - Munindar Singh and Michael Huhns

  21. BDI • Deciding on what goals to achieve and how to achieve them • Beliefs – the information an agent has about its surroundings • Desires – the things that agent would like to see achieved • Intentions – things that an agent is committed to doing • A BDI architecture addresses how beliefs, desires and intentions are represented, updated and processed Service-Oriented Computing: Semantics, Processes, Agents - Munindar Singh and Michael Huhns

  22. Sensor input brf beliefs Generate options desires filter intentions action Generic BDI Architecture Action output Service-Oriented Computing: Semantics, Processes, Agents - Munindar Singh and Michael Huhns

  23. Architecture of BDI-Based Agent Execution Cycle: • New information arrives that updates beliefs and goals • Actions are triggered by new beliefs or goals • A triggered action is intended • An intended action is selected • That intention is activated • An action is performed • New beliefs or goals are stored • Intentions are updated Service-Oriented Computing: Semantics, Processes, Agents - Munindar Singh and Michael Huhns

  24. Web Ontology Language – Services (OWL-S) An OWL-S service description provides • Declarative ads for properties and capabilities, used for discovery • Declarative APIs, used for execution • A declarative description of services -- based on their inputs, outputs, preconditions, and effects -- used for composition and interoperation Service-Oriented Computing: Semantics, Processes, Agents - Munindar Singh and Michael Huhns

  25. OWL-S Service Ontology Service-Oriented Computing: Semantics, Processes, Agents - Munindar Singh and Michael Huhns

  26. OWL-S Compared to UDDI Service-Oriented Computing: Semantics, Processes, Agents - Munindar Singh and Michael Huhns

  27. OWL-S Service Model Service-Oriented Computing: Semantics, Processes, Agents - Munindar Singh and Michael Huhns

  28. OWL-S Example: Processing Book Orders Service-Oriented Computing: Semantics, Processes, Agents - Munindar Singh and Michael Huhns

  29. OWL-S IOPE’s for Bookstore Example Service-Oriented Computing: Semantics, Processes, Agents - Munindar Singh and Michael Huhns

  30. Composition as Planning Service-Oriented Computing: Semantics, Processes, Agents - Munindar Singh and Michael Huhns

  31. Rules Service-Oriented Computing: Semantics, Processes, Agents - Munindar Singh and Michael Huhns

  32. Chapter 15 Summary Service-Oriented Computing: Semantics, Processes, Agents - Munindar Singh and Michael Huhns

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