Modeling Deployment and Mobility Issues in Multiagent Systems

AOT Lab
Dipartimento di Ingegneria
dell’Informazione
Università degli Studi di Parma
Unifying MAS Meta-Models
ADELFE, Gaia & PASSI
Carole Bernon, Massimo Cossentino, Marie-Pierre Gleizes,
Paola Turci and Franco Zambonelli
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
TFG AOSE, Rome, July 2004
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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
Message
-Comm_act : Performative
Agent
-Name : String
Role
-Name : String
-Initiator/ Participant
1
*
Communication
-Name
-Exchanged Knowledge : Ontology
-Content Language
1..*
1
AIP
-Name : String
Performative
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Agent Interactions
 No relevant differences
 ADELFE: agents
can communicate
indirectly using
environment
 Gaia:
communication
mediated by the
environment seen
as a side effect
TFG AOSE, Rome, July 2004
Message
-Comm_act : Performative
Agent
Role
-Name : String
-Initiator/ Participant
-Name : String
1
1..*
0..1
Representation
1..*
*
Communication
-Name
-Exchanged Knowledge : Ontology
-Content Language
Acts on/
Interacts
with
1..*
1
AIP
1
Environment
0..*
-Name : String
Resource
-Name : String
Performative
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Agent Interactions
 No relevant differences
 ADELFE: agents
can communicate
indirectly using
environment
 Gaia:
communication
mediated by the
environment seen
as a side effect
Concept
Message
-Comm_act : Performative
Agent
Role
-Name : String
-Initiator/ Participant
-Name : String
1
1..*
0..1
1
Representation
1..*
*
Communication
-Name
-Exchanged Knowledge : Ontology
-Content Language
Acts on/
Interacts
with
1..*
1
AIP
1
-Name : String
0..*
0..1
Ontology
1
1
Environment
Resource
-Name : String
Describes
Performative
1
Predicate
Action
-PermittedAction
-Act
1
 ADELFE: ontologies have not to be modelled; agents are
able to adapt to the environment and other agents
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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
Organization
Organizational Structure
*
-Control regime
-Topology
0..1
1
-observes
0..*
 Gaia:
organization =
primary
abstraction
 PASSI: services
and scenarios
Service
Organizational Rule
Belongs
SafetyRule
LivenessRule
-Input
-Output
-Pre-conditions
-Post-conditions
0..*
1..*
Agent
NCS
Cooperation rules
0..*
0..*
-Name : String
0..*
Scenario
1..*
0..*
Role
-Name : String
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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?
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