Semantically Federating Multi-Agent Organizations

R. Cenk ERDUR, Oğuz DİKENELLİ, R. Cenk ERDUR, Oğuz DİKENELLİ, İnanç SEYLAN, Önder GÜRCAN.İnanç SEYLAN, Önder GÜRCAN.

AEGEANT-S Group,AEGEANT-S Group,

Ege University, Dept. of Computer Eng.,Ege University, Dept. of Computer Eng.,

Bornova-İzmir, Turkey.Bornova-İzmir, Turkey.

AEGEANT-S Group -1/2 The “Agent and Semantic Web” (Aegeant-S) The “Agent and Semantic Web” (Aegeant-S)

group in our department works on several projects group in our department works on several projects related with agent systems.related with agent systems.

Our main and the most important project is to Our main and the most important project is to develop a semantic web enabled and FIPA-develop a semantic web enabled and FIPA-compliant agent platform. => compliant agent platform. => “SEAEGEANT”“SEAEGEANT”

““SEAGEANT” is a pioneering work in this area.SEAGEANT” is a pioneering work in this area. The name “SEAEGEANT” is chosen to emphasize The name “SEAEGEANT” is chosen to emphasize

that the final product is athat the final product is a semantic websemantic web enabled enabled agentagent platform and it is developed in platform and it is developed in Aegean Aegean (Ege) (Ege) University. University.

AEGEANT-S Group -2/2

Staff:Staff: Assoc. Prof. Dr. Oğuz Dikenelli Assoc. Prof. Dr. Oğuz Dikenelli

(Coordinator)(Coordinator) Asst. Prof. Dr. R. Cenk ErdurAsst. Prof. Dr. R. Cenk Erdur 4 Ph.D. student research assistants.4 Ph.D. student research assistants. M.Sc. and undergraduate students.M.Sc. and undergraduate students.

Project Web Address: Project Web Address: http://aegeants.ege.edu.trhttp://aegeants.ege.edu.tr

The Problem Tackled in this Paper

With the advances in the agent development With the advances in the agent development frameworks, tools and methodologies, it now frameworks, tools and methodologies, it now needs less effort and time to develop a multi-agent needs less effort and time to develop a multi-agent system for an organization. As a result of this system for an organization. As a result of this progress, we expect a large number of multi-agent progress, we expect a large number of multi-agent organizations to exist on the Internet.organizations to exist on the Internet.

In such an environment, one of the major In such an environment, one of the major challenges will be the establishment of an challenges will be the establishment of an infrastructure for the co-operation of multi-agent infrastructure for the co-operation of multi-agent organizations providing services in similar organizations providing services in similar domains. domains.

... ...

...

Other multi-agentorganizations providing

services in similar domains. For example, in

“Tourism” domain......

Co-operations between Multi-agent Organizations

Org.-1

Org.-2 Org.-3

If request cannotbe satisfied here, thenthe most semanticallyrelated organizations should be found...

? ?

Proposed Solution –1/3

For the co-operation of multi-agent For the co-operation of multi-agent organizations, an infrastructure providing organizations, an infrastructure providing the semantic interoperation of the multi-the semantic interoperation of the multi-agent organizations has been proposed. agent organizations has been proposed.

Proposed Solution –2/3

The concept of “Federation” has been proposed.The concept of “Federation” has been proposed. A federation defines the common A federation defines the common

characteristics of multi-agent organizations in a characteristics of multi-agent organizations in a domain.domain.

The federation directory service and the The federation directory service and the federation ontology service are introduced for federation ontology service are introduced for discovering the semantically related multi-discovering the semantically related multi-agent organizations in a federation. A semantic agent organizations in a federation. A semantic matching algorithm has been used in the matching algorithm has been used in the federation directory service.federation directory service.

Proposed Solution –3/3

Currently, there are some FIPA (Foundation for Currently, there are some FIPA (Foundation for Intelligent Physical Agents) specifications Intelligent Physical Agents) specifications discussing the interoperability of multi-agent discussing the interoperability of multi-agent systems, but these specifications define the systems, but these specifications define the standards for interoperability in message transport standards for interoperability in message transport protocol level, not in semantic level.protocol level, not in semantic level.

FIPA’s message transport level standards are of FIPA’s message transport level standards are of course important, but are not enough for high-course important, but are not enough for high-level co-operation. level co-operation. Hence, in this paper we try to Hence, in this paper we try to fill in this gap.fill in this gap.

The Concepts of Semantic Interoperability

Platform-1 Platform-2 Platform-N

MultiAgentOrg. -1

MultiAgent

Org. -K.....

MultiAgentOrg. -1

MultiAgent

Org. -K.....

MultiAgentOrg. -1

MultiAgent

Org. -K.....

Federation -1 Federation -M

Federation -1Directory Service

Federation - MDirectory Service

Federation -1Ontology Service

Federation – MOntology Service

Platform

Physical infrastructure in which the agents are Physical infrastructure in which the agents are deployed. It includes basic services as:deployed. It includes basic services as: Agent management serviceAgent management service Agent directory serviceAgent directory service Message transport serviceMessage transport service

For example, JADE or RETSINA are For example, JADE or RETSINA are implemented agent platforms. FIPA, defines the implemented agent platforms. FIPA, defines the standards for an agent platform. If a platform standards for an agent platform. If a platform implementation follows the FIPA standards, then implementation follows the FIPA standards, then it is called as a FIPA-compliant platform, such as it is called as a FIPA-compliant platform, such as JADE.JADE.

Multi-agent Organization A multi-agent organization is a multi-agent system A multi-agent organization is a multi-agent system

designed and implemented based on specified designed and implemented based on specified requirements in a specific domain.requirements in a specific domain.

A multi-agent organization uses the basic services A multi-agent organization uses the basic services provided by the platform on which it is deployed.provided by the platform on which it is deployed.

We try to establish an infrastructure for the co-We try to establish an infrastructure for the co-operation of multi-agent organizations; hence, at operation of multi-agent organizations; hence, at the conceptual level each multi-agent platform is the conceptual level each multi-agent platform is taken as a seperate entity in terms of semantic taken as a seperate entity in terms of semantic interoperability. interoperability.

Federation –1/2

A federation established for a specific domain A federation established for a specific domain defines the common characteristics of the multi-defines the common characteristics of the multi-agent organizations in that domain. In addition, agent organizations in that domain. In addition, federational rules such as pricing policy, federational rules such as pricing policy, certification can also be defined.certification can also be defined.

We use the concept of federation not in the same We use the concept of federation not in the same sense with the federation concept in the federated sense with the federation concept in the federated architecture, which has been defined by architecture, which has been defined by (Genesereth and Ketchpel, 1994) as an alternative (Genesereth and Ketchpel, 1994) as an alternative to direct communication in agent systems. to direct communication in agent systems.

Federation –2/2

Multi-agent organizations register to the Multi-agent organizations register to the “Federation Directory Service - FDS” using a “Federation Directory Service - FDS” using a specific FDS ontology.specific FDS ontology.

The ontologies in a federation are maintained by The ontologies in a federation are maintained by the “Federation Ontology Service – FOS”.the “Federation Ontology Service – FOS”.

FDS, is the key element in the architecture, since it FDS, is the key element in the architecture, since it can be searched semantically to discover the can be searched semantically to discover the semantically related multi-agent organizations.semantically related multi-agent organizations.

Conceptual Architecture

Over IIOPProtocol

ACL Msgs

Message Transport Service

DirectoryService

Agent-1

Platform

Agent Management

Service

Agent-N

FederationDirectory

Service(FDS)

PMS

MessageTransportServicesof Other

Platforms

Agent-K

:

...

FederationOntologyService(FOS)

Multi-agentOrganization-1 Multi-agent

Organization-N

Federation

MatchingEngine

Ontological Infrastructure

There are three kinds of ontologies in the There are three kinds of ontologies in the proposed architecture:proposed architecture: Organization Directory Service OntologyOrganization Directory Service Ontology Federation Directory Service OntologyFederation Directory Service Ontology Domain OntologyDomain Ontology

Organization Directory Service Ontology

This ontology is used by the agents in a This ontology is used by the agents in a multi-agent organization for registering their multi-agent organization for registering their services to the organization’s directory services to the organization’s directory service. The requester agents in a multi-service. The requester agents in a multi-agent organization also use this ontology to agent organization also use this ontology to search their local organization’s directory search their local organization’s directory service. We can say that this ontology is the service. We can say that this ontology is the internal ontology of a multi-agent internal ontology of a multi-agent organization in a specific domain.organization in a specific domain.

Federation Directory Service Ontology

A multi-agent organization uses this A multi-agent organization uses this ontology to register its meta-knowledge to ontology to register its meta-knowledge to the federation’s directory service.the federation’s directory service.

This ontology is also used in the searching This ontology is also used in the searching of the federation directory service in order of the federation directory service in order to match the semantically related multi-to match the semantically related multi-agent organizations. agent organizations.

Domain Ontology

A domain ontology consists of domain A domain ontology consists of domain concepts, relations between these concepts concepts, relations between these concepts and rules.and rules.

Both the organization directory service and Both the organization directory service and the federation directory service ontologies the federation directory service ontologies have a domain specific part, which is have a domain specific part, which is expressed using terms from the domain’s expressed using terms from the domain’s ontology.ontology.

Comparing the Domain Specific Parts of the FDS and Organization Directory Service Ontologies The domain specific part of the federation The domain specific part of the federation

directory service (FDS) ontology is less directory service (FDS) ontology is less detailed and contains more high level detailed and contains more high level concepts than the organization directory concepts than the organization directory service ontology. This is because FDS service ontology. This is because FDS ontology aims at ontology aims at classifying the classifying the organizations at a higher levelorganizations at a higher level, while the , while the organization directory service ontology is organization directory service ontology is used in used in representing the services of representing the services of individual agentsindividual agents within an organization. within an organization.

General Structure of the FDS Ontology

Multi-agent OrganizationDescription

MTS_Address of the PlatformSupported_Content_LanguagesSupported_Ontology_LanguagesSupported_ProtocolsSupported_Encoding

Provider

// Attributes related withthe provider organization such ascontact address, web-site, etc.

hasProvider

Domain

hasDomainDomain_nameDomain_ontology_nameDomain_dependent_advertisement_content

This attribute is expressedin a language such as OWLand constitues the domain dependent part of the FDS-Ontology.

Collaboration Diagram for Semantic Matching of Multi-Agent Organizations

Agent

LocalDirectory

Service1

PMS

FDSRemote

Directory Service

RemoteAgents

23

45

6

7

8

9

Semantic Matching Algorithm in the FDS

It is derived from the previous work on It is derived from the previous work on semantic matching of web service semantic matching of web service capabilities: capabilities: (Paolucci, M. et. al., 2002)(Paolucci, M. et. al., 2002) (Li, L. and Horrocks, I., 2003)(Li, L. and Horrocks, I., 2003)

Semantic Matching Algorithm in the FDS

Match(expression, Multi-AgentOrganizationDescriptions) {Match(expression, Multi-AgentOrganizationDescriptions) {degreeOfMatch = expression.getOperation();degreeOfMatch = expression.getOperation();request = expression.getValue();request = expression.getValue();matchedOrganizations = emptyList;matchedOrganizations = emptyList;forall org_descp in Multi-AgentOrganizationDescriptions do {forall org_descp in Multi-AgentOrganizationDescriptions do {

forall adv in org_descp.getAdvertisements() do {forall adv in org_descp.getAdvertisements() do { if (calculateDegreeOfMatch(request, adv) == degreeOfMatch)if (calculateDegreeOfMatch(request, adv) == degreeOfMatch) then matchedOrganizations.append(org_descp)then matchedOrganizations.append(org_descp)}}

return matchedOrganizations;return matchedOrganizations;}}

}}

Conclusion and Future Work

Establishing agent federations and using semantic Establishing agent federations and using semantic matching to discover a related multi-agent matching to discover a related multi-agent organization in a federation:organization in a federation: Forms the basis for constructing open, large-Forms the basis for constructing open, large-

scale and scalable multi-agent systems. scale and scalable multi-agent systems. Makes it possible for multi-agent organizations Makes it possible for multi-agent organizations

in similar domain to co-operate effectively.in similar domain to co-operate effectively. The idea of confederation based on agent The idea of confederation based on agent

federations will be considered as a future work.federations will be considered as a future work.

Thank you for listening...

Contact:

erdur@staff.ege.edu.tr