Integrating aPriority-Based Scheduler of

Behaviours in JADE

Juan A. Suárez-RomeroAmparo Alonso-BetanzosBertha Guijarro-Berdiñas

Laboratory for Research and Development in Artificial Intelligence

Department of Computer Science, University of A Coruña, Spain

Supported under PGIDT03TIC10501PR project

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Outline

• JADE• Need for priorities• Current implementation of JADE’s scheduler

• Proposed implementation of priority-based scheduler

• Examples• Summary

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JADE

• Java Agent DEvelopment Framework

• FIPA compliant

• Agent tasks encapsulated in Behaviours

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.public void action();

public boolean done();...

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.public void action();

public boolean done();...

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.public void action();

public boolean done();...

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.publicvoidaction();

publicbooleandone();...

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.publicvoidaction();

publicbooleandone();...

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.publicvoidaction();

publicbooleandone();...

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.publicvoidaction();

publicbooleandone();...

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.publicvoidaction();

publicbooleandone();...

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.publicvoidaction();

publicbooleandone();...

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Need for priorities

• Agent that resolves requests from other agents.– Some requests requires more attention that

others

Listener

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Need for priorities

• Agent that uses its full time

– In normal time, it executes several specific tasks

– When it is idle (i.e. these tasks can not be executed)

it runs other tasks of maintenance.

Specific Tasks Idle Tasks

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Adding priorities to JADE

• Add priorities to Behaviours

– Reuse of existing Behaviours → Wrapper

• Adding a scheduler that manages these

encapsulated Behaviours

– Add a scheduler as add-on → CompositeBehaviour

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Behaviours with priority

• Each Behaviour are encapsulated in a wrapper that adds priority

• Wrapper is transparent to users• Priority is a number ≥0

• The lesser the number, the greater the priority• Two priorities

– Static priority: specified by user

– Dynamic priority: used internally by the scheduler

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Current implementation

• Two class of CompositeBehaviour– ParallelBehaviour

B1 B2 B3 B4

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ParallelPriorityBehaviour

• Manages sub-behaviours in a parallel way using priorities

B4

1

1

B3

0

0

B2

1

1

B1

2

2

B3

0

0

DynamicPriority

StaticPriority

Ready

List

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ParallelPriorityBehaviour

• Manages sub-behaviours in a parallel way using priorities

B4

1

1

B2

1

1

B1

2

2

Ready

List

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ParallelPriorityBehaviour

• Manages sub-behaviours in a parallel way using priorities

B4

1

0

B2

1

0

B1

2

1

Ready

List

B2

1

0

B4

1

0

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ParallelPriorityBehaviour

• Manages sub-behaviours in a parallel way using priorities

B4

1

1

B2

1

1

B1

2

1

Ready

List

B2

1

1

B4

1

1

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ParallelPriorityBehaviour

• Manages sub-behaviours in a parallel way using priorities

B4

1

1

B2

1

1

B1

2

1

Ready

List

B2

1

1

B4

1

1

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a P

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ESAW’06

ParallelPriorityBehaviour

• Manages sub-behaviours in a parallel way using priorities

B4

1

0

B2

1

0

Ready

List

B2

1

0

B4

1

0

B1

2

0

B1

2

0

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a P

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ESAW’06

ParallelPriorityBehaviour

• Manages sub-behaviours in a parallel way using priorities

B4

1

1

B2

1

1

Ready

List

B2

1

1

B4

1

1

B1

2

2

B1

2

2

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Inte

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a P

rior

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Bas

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ched

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of B

ehav

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s in

JA

DE

ESAW’06

ParallelPriorityBehaviour

• Manages sub-behaviours in a parallel way using priorities

B4

1

1

B2

1

1

Ready

List

B2

1

1

B4

1

1

B1

3

3

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a P

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Current implementation

• Two class of CompositeBehaviour– ParallelBehaviour– SequentialBehaviour

B1 B2 B3 B4

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SequentialPriorityBehaviour

• Manages sub-behaviours in a sequential way using priorities

B2

1

B3

0

B1

3

B4

1

StaticPriority

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ESAW’06

SequentialPriorityBehaviour

• Manages sub-behaviours in a sequential way using priorities

B2

1

B1

3

B4

1

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a P

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ESAW’06

SequentialPriorityBehaviour

• Manages sub-behaviours in a sequential way using priorities

B2

1

B1

3

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a P

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ESAW’06

SequentialPriorityBehaviour

• Manages sub-behaviours in a sequential way using priorities

B2

1

B1

0

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a P

rior

ity-

Bas

ed S

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of B

ehav

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JA

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ESAW’06

Need for priorities

• Agent that resolves requests from other agents.– Some requests requires more attention that

others

Listener

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Inte

grat

ing

a P

rior

ity-

Bas

ed S

ched

uler

of B

ehav

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s in

JA

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ESAW’06

Need for priorities. Solution

• Encapsulate each new Behaviour inside a ParallelPriorityBehaviour

Listener

1

P1

P3

P2

P4

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a P

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ity-

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ched

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of B

ehav

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JA

DE

ESAW’06

Need for priorities

• Agent that uses its full time

– In normal time, it executes several specific tasks

– When it is idle (i.e. these tasks can not be executed)

it runs other tasks of maintenance.

Specific Tasks Idle Tasks

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a P

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ESAW’06

Need for priorities. Solution

• Use SequentialPriorityBehaviour to encapsulate specific and idle tasks

SequentialPriorityBehaviour

ParallelBehaviour [1] ParallelBehaviour [2]

Specific Task 1

Specific Task 2

Specific Task 3

Idle Task 1

Idle Task 2

Idle Task 3

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Summary

• Two new priority-based scheduler Behaviours are proposed– ParallelPriorityBehaviour– SequentialPriorityBehaviour

• They are able to run as the current scheduler implementations

• The use of priorities penalizes the performance of the scheduler

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T ha n

ky o

uf o

r

y ou r

a tt e

n ti o

n

Integrating a Priority-Based Scheduler of Behaviours in JADE