AOT LabDipartimento di Ingegneria

dell’InformazioneUniversità degli Studi di Parma

Unifying MAS Meta-Models ADELFE, Gaia & PASSI

Carole Bernon, Massimo Cossentino, Marie-Pierre

Gleizes, Paola Turci and Franco Zambonelli

2TFG AOSE, Rome, July 2004

Agent-Oriented vs. Object-Oriented

Design a system Instantiate a meta-model OO context - design rely on a common denominator

• Universally accepted concept of object and related meta‑model of object-oriented systems

AO context - to date, no common denominator• Each methodology has its own concepts and system structure

In the agent world the meta-model is the critical element

when applying the “method engineering” paradigm

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Reasons to Unify

Meta-model = means to unify concepts Unique meta-model, a way of unifying the different

concepts

Helping designer to build a meta-model depending on the system he needs Choice of useful elements

• From the “omni-comprehensive” MAS meta-model

Composition of process• “Method fragment” selection phase

Model coherence checking by CASE tools Unification eases model transformation

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MAS Meta-Model for ADELFE

no predefined organization• local goal• cooperative• detect and remove NCS

cognitive and behavioural representation

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Gaia Methodology

First version Designed to handle small-scale, closed agent-based

systems Modelled agents, roles, interactions Missed in modelling explicitly the social aspects of a

MAS

Official extension of Gaia Thought for open agent systems Focused on the social organization of the system

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MAS Meta-Model for Gaia

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MAS Meta-Model for PASSI

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Towards a Unifying MAS Meta-Model

In order to define a unifying meta-model we will consider the following specific aspects: Agent structure Agent interactions Agent society and organizational structure Agent implementation

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Agent Structure

ADELFE: cooperative agents

Gaia and PASSI: composition of roles

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Agent Structure - Considerations

None imposes a specific classical agent architecture Seen as some kind of low level architectures that can be adopted

during MAS implementation

None explicitly deals with goals and plans ADELFE

• Notion of goal is only used to determine skills• Plans are built at run-time by the system

Gaia• The concept of “goal” is implicit in roles• Plans play no explicit role

PASSI• Goals are considered as non functional requirements• Plans are modelled as algorithms (activity diagrams)

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Agent Interactions

No relevant differences

-Name : String

Agent

-Name : String

Role

-Name-Exchanged Knowledge : Ontology-Content Language

Communication

-Name : String

AIP

-Comm_act : Performative

Message

Performative

-Initiator/ Participant

1 *

1

1..*

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Agent Interactions

-Name : String

Agent

-Name : String

Role

-Name-Exchanged Knowledge : Ontology-Content Language

Communication

-Name : String

AIP

-Comm_act : Performative

Message

Performative

-Initiator/ Participant

1 *

1

1..*

-Name : String

Resource

0..*

1..*

Representation

0..1

Environment

Acts on/Interacts

with1..*

1

No relevant differences

ADELFE: agents can communicate indirectly using environment

Gaia: communication mediated by the environment seen as a side effect

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Agent Interactions

No relevant differences

-Name : String

Agent

-Name : String

Role

Ontology

Concept

-Act

ActionPredicate

-Name-Exchanged Knowledge : Ontology-Content Language

Communication

-Name : String

AIP

-Comm_act : Performative

Message

Performative

-Initiator/ Participant

1 *

1

1..*

-Name : String

Resource

0..*

1..*

Representation1

0..1

0..1

Environment11

Describes

-PermittedAction

1

1

Acts on/Interacts

with1..*

1

ADELFE: ontologies have not to be modelled; agents are able to adapt to the environment and other agents

ADELFE: agents can communicate indirectly using environment

Gaia: communication mediated by the environment seen as a side effect

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Agent Society and Organizational Structure

ADELFE: no predefined organization

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Agent Society and Organizational Structure

ADELFE: no predefined organization

Gaia: organization = primary abstraction

PASSI: services and scenarios -Name : String

Agent

-Name : String

RoleScenario 0..*1..*

-Input-Output-Pre-conditions-Post-conditions

Service

0..*

1..*

Cooperation rulesNCS

-Control regime-Topology

OrganizationOrganizational Structure*

Organizational Rule

SafetyRule LivenessRule

-observes1

0..*

0..1

0..*

Belongs

0..* 0..*

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Agent Implementation

ADELFE The problem of the system implementation has not been

treated yet; no platform has been imposed

Gaia Totally abstract from implementation

PASSI FIPA compliant systems

• Direct map among the most important elements of the model and their implementation

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Proposal for a Unifying Meta-model

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Conclusion

Societies with or without predefined organizations (open systems) Generic agent (cooperative or not)

• Follows organizational or cooperation rules

Possibility of identifying three domains Improvements: an agent has a representation of

the environment expressed via an ontological model

Step towards a unique meta-model A unifying framework for the systems produced with

different approaches

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Open Questions

Can a unique meta-model exist? What description level has to be reached? How may designers choose meta-model

elements? What kind of tools may ease their work?