final presentation exception management · final presentation phd candidate exception management...

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Eric Platon

Final PresentationPhD Candidate

Exception Management

Multi-Agent Systemsin

June 25th, 2007

Dr. Nicolas Sabouret Pr. Shinichi Honiden

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Multi-Agent Systems

3

Multi-Agent Systems

Distributed Systems

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DistributedSystems

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“Fallacy”Robustness is inherent with MAS

[Haegg, 1996; Brewer,2000; Klein et al., 2003; Hohpe, 2007]

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Robustness is inherent with MAS

Robustness is not free

[Haegg, 1996; Brewer,2000; Klein et al., 2003; Hohpe, 2007]

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How to buildmore robustdistributed systems

with multi-agent technologies?

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Exception Handling

Simple, Powerful, Elegant

Limited in Distributed Systems

Robustness in Software

[Goodenough, 1975; Xu et al., 1998; Issarny,2000/2001; Romanovsky,2001;Klein et al., 2003]

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Exception Management in Multi-Agent Systems

Exception in MAS are not only programming-like exceptionsThesis, Part 1

Exception in MAS should be supported at three levels: Code level Agent level System level

Thesis, Part 2

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Exception in MAS are not only programming-like exceptions

Thesis, Part 1

Engineering model fordistributed,open,heterogeneoussystems

What are MAS?

[Ferber,1995] & [Weiss,1998]

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Deployment EnvironmentDB DB

Resources

Hardware

What are MAS?

Interactive software process

Autonomous: Capable to decide

Perception Action

Processing

Knowledge Agents

WS

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Deployment EnvironmentDB DB

Resources

Hardware

What are MAS?

Interactive software process

Autonomous: Capable to decide

Perception Action

Processing

Knowledge Agents

WS

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Exceptional Conditions

Related to Interaction Protocols

Initiator Participant

request

reply

DB

Mission: Register to CS-2

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Related to Interaction Protocols

Please register me to CS-2

DB

Need CS-1 credit, no record


request

reply

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Related to the Environment

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Expected Reactions toExceptional Conditions

Self-Adaptive Behaviors

Based on Interaction & Autonomy

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[Act]Agentor

Resource

ActEvent

ExceptionNormal

TargetNotion of Exception

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What is an exception usually?

Class MailBox, Method sendMessage

Invoker Operation

try {Message m = new Message(id,from,to,content);send(m);

} catch (SendException exc) {System.err.print("Exception!");

}

[Goodenough, 1975; Parnas 1976; Randell, 1976]

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Invoker Operation



}

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Invoker Operation



}

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Invoker Operation Exception



}

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Exception object/signal





}

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Event

?

Exception

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EventException

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Event

An agent exception is the evaluationby the agent of a perceived event asunexpected.

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Two categories

Agent Level System Level

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Exceptions in Multi-Agent Systems

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Code

try {...

} catch (IOException e) {...

}

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Code

Agent

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Code

Agent

System

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Code

Agent

SystemAgent

ProgrammingException

Exception

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OutlineException Management in Multi-Agent Systems

Exception in MAS are not only programming-like exceptionsThesis, Part 1


Thesis, Part 2

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TowardEngineering Practice

System Designer

Thesis, Part 2Exception in MAS should be supported at three levels, CAS

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Separation of Concerns

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Code

Agent

System

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Our ProposalTo

Agent-LevelException Management

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Perception

Processing

Perception

Processing

Perception

Processing

Perception Action

Processing

Knowledge

Perception Action

Processing

Knowledge Agents

Exception-Ready Agents

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Perception

Processing

Perception

Processing

Perception

Processing

Perception Action

Processing

Knowledge

Perception Action

Structure of Execution

Structure of Knowledge

Environment

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Environment

ProtocolEnactmentsProtocol

EnactmentsProtocol

Expectations


EnactmentsOperator

Expectations

ActionRevision

ASM

ProtocolsOperators


EnactmentsProtocol

Enactments

Perception Action

PlansGoals

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Perception

Processing

Perception

Processing

Perception

Processing

Perception Action

Processing

Knowledge

Environment

ASM


EnactmentsProtocol

Expectations


EnactmentsOperator

Expectations

ExceptionDetection

ProtocolsOperators


EnactmentsProtocol

Enactments

Violation

Perception Action

GoalsPlans

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Exception Detection

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Perception

Processing

Perception

Processing

Perception

Processing

Perception Action

Processing

Knowledge


EnactmentsProtocol

Expectations


EnactmentsOperator

Expectations

Environment

ProtocolsOperators


EnactmentsProtocol

EnactmentsASM

Perception Action

GoalsPlans

doAction(x)

effect

reffect(doAction, expression, effect)

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Perception

Processing

Perception

Processing

Perception

Processing

Perception Action

Processing

Knowledge


EnactmentsProtocol

Expectations


EnactmentsOperator

Expectations

Environment

ProtocolsOperators


EnactmentsProtocol

EnactmentsASM

Perception Action

GoalsPlans

effect?

reffect(doAction, expression, effect)

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Perception

Processing

Perception

Processing

Perception

Processing

Perception Action

Processing

Knowledge


EnactmentsProtocol

Expectations


EnactmentsOperator

Expectations

Environment

ProtocolsOperators


EnactmentsProtocol

EnactmentsASM

Perception Action

GoalsPlans

ExceptionDetection

Violation

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Perception

Processing

Perception

Processing

Perception

Processing

Perception Action

Processing

Knowledge


EnactmentsProtocol

Expectations


EnactmentsOperator

Expectations

Environment

ProtocolsOperators


EnactmentsProtocol

Enactments

Perception Action

GoalsPlans

ASM

ExceptionDetection

Violation

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Action Selection

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Expectations IncomingEvent

Update the agent state Select next action

OperatorProtocolGoal & Plan Revision

Commit actionRelated to ANA, [Maes, 1991]

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Example

x


cfp

accept

cnet(x,[])go(x)

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reffect( cnet(x, []),T,have(x) Λmoney(y=y-price(x)) )

x

&© classroomclipart.com

-x

reffect( go(x),T,position(x) )

x

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context( go(x), ¬position(x) )

X

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xxxx

xx

context( cnet(x, [shop1, ..., shopn]),need(x) Λ available(x, [shop1, ..., shopn]) )

xxxx

xxxx

W

x?

Y

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Machine parts producers

Energy producers

Machinery producers

ValidationEnergy Consortium Scenario

DistributedOpenHeterogeneous

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Machine parts producers

Energy producers

Machinery producers



Test Exception: Delay Requests

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Implementation Styles

No Exception Management

Plain Management

EMS Approach

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Tasks forAgent Exception Code

(Intrinsic) Robustness

Actions

High

EMS

Ad hoc

Low

Plain

56Min Max Plateau0

0.250.50.751

1.251.51.752

2.252.52.753

3.253.53.75

Execution Cycles per 100 ms

BaselinePlainEMS

Time (s)

57Min Max Plateau0

0.250.50.751

1.251.51.752

2.252.52.753

3.253.53.75

Execution Cycles per 100 ms

BaselinePlainEMS

Common Profile

Time (s)

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Time (ms)0

500

1000

1500

2000

2500

3000

3500

4000

4500

5000

5500

Average Execution Time

BaselinePlainEMS

Trade-offRobustness

vs.Execution CostTime (ms)

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Agent-LevelException Management

EMS

Execution Overhead

Separation of ConcernsTask reduced to Action Design1

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Our ProposalTo

System-LevelException Management

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Software

Agent

System

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Application layer

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Application layer

[Haegg, 1996; Klein et al., 2003; Shah et al., 2005]

System-Level Exception Management

Sentinels

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Perception

Processing

Perception

Processing

Perception

Processing

Perception Action

Processing

Knowledge

Perception Action

Processing

KnowledgeAgent

Perception

Processing

Perception

Processing

Perception

Processing

Perception Action

Processing

Knowledge

Perception Action

Processing

KnowledgeSentinel

Overridden Autonomy

65

Perception

Processing

Perception

Processing

Perception

Processing

Perception Action

Processing

Knowledge

Perception Action

Processing

KnowledgeAgent

Perception

Processing

Perception

Processing

Perception

Processing

Perception Action

Processing

Knowledge

Perception Action

Processing

KnowledgeSentinel

Overridden Autonomy

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AgentLocal View

WhyWaiting?

System-Wide Support

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Blocked

SentinelEnlarged View

System-Wide Support

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Architecture with Softbody

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Perception ActionPerception Action

Agent

Perception

Processing

Perception

Processing

Perception

Processing

Perception Action

Processing

Knowledge

Perception Action

Processing

KnowledgeSentinel

PublicState

Update

Softbody

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Agent

Perception

Processing

Perception

Processing

Perception

Processing

Perception Action

Processing

Knowledge

Perception Action

Processing

KnowledgeSentinel

PublicState

Update

Softbody

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Machine parts producersEnergy producers

Machinery producers



Sentinels

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Agent

Public State

Running Order

Expected Completion Date

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A

RO ECD

B

RO ECD

S

Contracting

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A

RO ECD

B

RO ECD

S

Contracting

EMS

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A

RO ECD

B

RO ECD

S

Contracting

Notification

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Analytical Evaluation

Communication Cost (n agents, worst)O(n2)

Heuristics allowing O(n) and O(1)

Compared to Original Sentinels

[Haegg, 1996; Dellarocas et al., 2000; Klein et al., 2003; Shah et al., 2005]

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Analytical Evaluation

[Haegg, 1996; Dellarocas et al., 2000; Klein et al., 2003; Shah et al., 2005]

Computational Complexity UnchangedArchitecture Change

Compared to Original Sentinels

“Economical” Change forAutonomy Respect

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Conclusion


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Towardsmore robustdistributed systemswith multi-agent technologies


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Thesis and Contributions

EMSSentinels(revised)

try {...

} catch (IOException e) {...

}

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Coupling between Exception Levels

Perspectives on

EM as Self-Organizing Mechanism

Support for Action Design and Consistency

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Acknowledgements

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Thank you for your attention

Eric Platon

June 25th, 2007

final presentation exception management · final presentation phd candidate exception management...

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