@lis agent communication, ontologies, protocols, semantic web 2003

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@lis agent communication, ontologies, protocols, semantic web 2003

  1. 1. Agentcommunication,ontologies,protocols,semanticWeb http://www.lsi.upc.es/~webia/KEMLG Agent communication, ontologies, protocols, semantic Web October 30, 2003 Luigi Ceccaroni, Steven Willmott
  2. 2. Agentcommunication,ontologies,protocols,semanticWeb Luigi Ceccaroni, Steven Willmott Problem  While there are all sorts of useful databases, services and modeling packages being developed by companies and universities, they all exist in isolated developmental bubbles. Each such tool expects the world to conform to its requirements. Since the tools are so valuable, the world will do exactly that, but …  … we expect to see vast resources applied to the problem of getting data from one bubble into another.  There is a fractured mess of data, services and modeling fiefdoms (feudos). The medium for data transfer will continue to be sleep-deprived individual human researchers until …
  3. 3. Agentcommunication,ontologies,protocols,semanticWeb Luigi Ceccaroni, Steven Willmott Solution  … the time when we know how to make software that is good at bridging bubbles on its own.  Ontologies are the semantic foundation of this software.  Intelligent agents are the autonomous components of this software
  4. 4. Agentcommunication,ontologies,protocols,semanticWeb Luigi Ceccaroni, Steven Willmott Key technology issues in the case of services  Service interaction over a network, and semantics  Service composition  Automated service components Restaurant Restaurant Restaurant Hotel Server Hotel DF Barcelona DF Paris ACL SL Ontologies
  5. 5. Agentcommunication,ontologies,protocols,semanticWeb http://www.lsi.upc.es/~webia/KEMLG Modeling an Agent Service Platform Deployment Communication Stack Design Methodology
  6. 6. Agentcommunication,ontologies,protocols,semanticWeb Luigi Ceccaroni, Steven Willmott Deploying an agent Platform  Machine  Any operating system  Outside the firewall (or with necessary access)  Permanent connection if possible  FIPA Compliant Agent Platform  “Roll your own”  Use one of the 20 or so available, better if it’s JADE  Install and Deploy the Platform  External Address  Register the platform  Create a group on [http://www.agentcities.net]  Register you platform data (address, name, …)  Activate the monitoring services
  7. 7. Agentcommunication,ontologies,protocols,semanticWeb Luigi Ceccaroni, Steven Willmott Communication Stack among agents Level Description Example Conversation Sequence of communicative acts related to a particular topic Communicating about buying and eating an apple Communicative Act Communication about a piece of content Requesting somebody to perform the action of eating an apple Content Expression Description of states of the world over objects Expressing the action of eating an apple Ontology Description of objects in the domain Meaning of apple and eat Syntax Representation of Content HTML, JPG, SQL Protocol Data exchange protocol HTTP, GIIOP, SMTP Transport Physical transport and low level transport protocols Optical Fiber, TCP-IP
  8. 8. Agentcommunication,ontologies,protocols,semanticWeb Luigi Ceccaroni, Steven Willmott Design Methodology for services  Service Specification  What functionality do we want? What agents do we need?  Design  Protocols: map into interaction sequences  Performatives (e.g.: ask, tell, advertise): find out which ones you need  Content Expressions: work out what content is needed  Ontology: build a domain model  Top-down design recommended  Bottom-up design might also be valid for very generic services
  9. 9. Agentcommunication,ontologies,protocols,semanticWeb Luigi Ceccaroni, Steven Willmott Need for Ontologies: a definition  Ontology, or semantic mapping, is the base of semantic processing. An ontology is a network of concepts, relationships and axioms to represent, organize, understand a domain of knowledge relevant to an organization. An ontology provides the common frame of reference for all applications in the environment. An ontology defines the applications’ domain and its boundaries.
  10. 10. Agentcommunication,ontologies,protocols,semanticWeb Luigi Ceccaroni, Steven Willmott Need for Ontologies: requirements  The meaning of the things referred to in the domain (Vocabulary)  To know what possible values exist (Vocabulary)  To know about underlying relationships among items (Conceptualization)  To know how to make inferences (Axioms)  To effectively interpret return values and parameter values
  11. 11. Agentcommunication,ontologies,protocols,semanticWeb Luigi Ceccaroni, Steven Willmott Other needs  Structured Content Expression  Content Languages structure content communication  Performatives  Two models: • One communication act with semantics Do this: easily understood but very general • A complex infinity of communication acts: user defined and often with no semantics defined  Method calls (actions) • Performatives pick a fixed action set with well defined and agreed semantics, and a broad coverage of most applications
  12. 12. Agentcommunication,ontologies,protocols,semanticWeb Luigi Ceccaroni, Steven Willmott Other needs  Interaction Protocols  String together several communicative acts (interactions) into a useful sequence, with coherent aim and semantic description  In general we require • Extended Interactions with multiple steps • Asynchronous Interactions • Link with Semantics (what does a certain sequence mean in total?)
  13. 13. Agentcommunication,ontologies,protocols,semanticWeb Luigi Ceccaroni, Steven Willmott Descriptions  Box-Diagram Descriptions  UML-based n o t - u n d e r s t o o d r e f u s e r e a s o n f a ilu re r e a s o n in fo rm D o n e (a c t io n ) in fo rm ( io ta x ( r e s u lt a c t io n ) x ) a g r e e r e q u e s t a c t io n
  14. 14. Agentcommunication,ontologies,protocols,semanticWeb Luigi Ceccaroni, Steven Willmott Information Exchange, SL, ontologies  Agent Communication uses:  asynchronous message passing  SL as content language  Terminals in SL often bottom out into:  Strings  Numerical constants (these need to be replaced by things in the ontology)  Example  ((action (agent-identifier :name X) (read-book :title “Fundamentals of SQL” :author …) ) ) FIPA Agent Management Ontology Domain Ontology
  15. 15. Agentcommunication,ontologies,protocols,semanticWeb Luigi Ceccaroni, Steven Willmott Frame Representation Frame Ontology agent-identifier FIPA-Agent-Management Parameter Description Presence Type name The symbolic name of the agent. Mandatory Word addresses A sequence of ordered transport addresses where the agent can be contacted. The order implies a preference relation of the agent to receive messages over that address. Optional Sequence of URL resolvers A sequence of ordered AIDs where name resolution services for the agent can be contacted. The order in the sequence implies a preference in the list of resolvers. Optional Sequence of agent- identifier
  16. 16. Agentcommunication,ontologies,protocols,semanticWeb Luigi Ceccaroni, Steven Willmott Agent-identifier  Example  (agent-identifier :name Arnold.Schwarzenegger :addresses (sequence http://www.governor.ca.gov, …) :resolvers (sequence (agent-identifier :name Hollywood.LA, …) ) - Green underlined items are named in the ontology - Orange italic items are values (may or may not be in the ontology) - Black items part of SL syntax
  17. 17. Agentcommunication,ontologies,protocols,semanticWeb Luigi Ceccaroni, Steven Willmott Service Modeling Recommendations from Agentcities experience
  18. 18. Agentcommunication,ontologies,protocols,semanticWeb Luigi Ceccaroni, Steven Willmott Distribute Complexity over Layers  (query-ref :sender …i :receiver …j :content (iota ?x (is_car :color red :make ford ) ) )  (request :sender …i :receiver …j :content (action j (send-information (iota ?x (is_car :color red :make ford ) ) ))Could be defined in any way the programmer likes
  19. 19. Agentcommunication,ontologies,protocols,semanticWeb Luigi Ceccaroni, Steven Willmott Distribute Complexity over Layers  The two versions are potentially equivalent  In the right hand version, semantics is redefined in the ontology  We could have a performative for everything or put everything in the ontology  We could push semantics UP 1. Have a performative for everything 2. Have very limited content language  Or push semantics DOWN 1. Use only “request” 2. Define the semantics of every request in the Ontology
  20. 20. Agentcommunication,ontologies,protocols,semanticWeb Luigi Ceccaroni, Steven Willmott Focus on Application Characteristics  What is happening at the application level?  Try to abstract away implementation details  Make ontologies generic  Concentrate on general descriptions of the world which feed into your application  This leads to greater re-use  Focus on the goals of the interactions between your agents  Not on the details of how your particular mechanism works
  21. 21. Agentcommunication,ontologies,protocols,semanticWeb Luigi Ceccaroni, Steven Willmott Use Real Data Sources  The Web is full of information  Ontologies and service models exist for many domains  When working in a domain, identify the industry standards body or group which guide consensus  Data sources  International and business organizations  Domain leading web sites  ebXML, BizTalk, UDDI, Jini community -> all producing and storing XML based examples  Dublin core
  22. 22. Agentcommunication,ontologies,protocols,semanticWeb Luigi Ceccaroni, Steven Willmott Work Top-Down  It keeps you focused on your application  Try to restrict your view (the generally intelligent agent is a while away…)  Build simple models first  Select the correct granularity (is a hotel an agent or should it be a hotel chain?)  Match the real world in granularity (hotels are independent but don’t often have their own websites)  Smaller granularity  More work  More potential re-use in other services
  23. 23. Agentcommunication,ontologies,protocols,semanticWeb Luigi Ceccaroni, Steven Willmott Be Rigorous  Formal models are important  and useless if they are not adhered to  Formal models are almost never adequate  If you need to deviate from them • Do so in a principled way • Document how and why you deviated • Feed them back to the community  Be rigorous in your descriptions  Precise specifications  Formal grammars  Correct use of the agreed semantics
  24. 24. Agentcommunication,ontologies,protocols,semanticWeb Luigi Ceccaroni, Steven Willmott Agentcities Examples Evening Organizer Perspective Travel Information Geo Information Cinema Guide Ratings Agent Event Organizer Perspective Ontology Ticket Market Talent Market Event Publicity Security Event Planner Personal Agent Evening Organiser Hotel Guide Restaurant FinderRestaurant Guide Restaurant Restaurant Restaurant Restaurant Restaurant Restaurant Restaurant Music Venue Restaurant Restaurant Restaurant Hotel Restaurant Restaurant Restaurant Band/ Performer Restaurant Restaurant Restaurant Cinema Restaurant Restaurant Restaurant Theatre Bank Personal Agent
  25. 25. Agentcommunication,ontologies,protocols,semanticWeb Luigi Ceccaroni, Steven Willmott Evening Organizer Personal Agent Evening Organiser Hotel Guide Restaurant Finder Restaurant Guide Restaurant Restaurant Restaurant Restaurant Restaurant Restaurant Restaurant Music Venue Restaurant Restaurant Restaurant Hotel Restaurant Restaurant Restaurant Band/ Performer Restaurant Restaurant Restaurant Cinema Restaurant Restaurant Restaurant Theatre Travel Information Geo Information Ratings Agent Cinema Guide Ticket Market Event News

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