i* Modeling of Agent-based RE Processes – A Basic Tutorial

i* Modeling of Agent-based RE Processes – A Basic TutorialProcesses – A Basic Tutorial

ROLE PLE Expert WorkshopROLE PLE Expert WorkshopLeicester, July 23, 2009

Ralf Klamma

Ch i f C t S i 5Chair of Computer Science 5,RWTH Aachen University, Germany

© www.role-project.eu

Technical LeaderCommunity Facilitator

Motivation - Traditional RE

• Emphasis on Late Phase RE• Emphasis on Late Phase RE• OO RE (Classes/Objects)• Ill-suited for Socio-Technical Systems

“What“ & “How“ but not “Why“• What & How , but not Why• Neglection of Stakeholder Interestsg• Early Choice between Alternatives

Agent-Oriented RE


R. Klamma, RWTH Aachen 2

Motivation - Agent-Oriented RE

• Intentional Agents pursuing Goalsg p g• Focus on Early Phase RE

S l R l t H /SW A t• Seamless Replacement Human/SW Agent• Continuous Adaptabilityp y

– New ComponentsNew Requirements– New Requirements

• Flexibility– Alternative Ways towards Goals– Open towards Unknown Components


Open towards Unknown ComponentsR. Klamma, RWTH Aachen 3

What is an Agent?

• Person, Organisation, Software• BDI: Beliefs – Desires – IntentionsBDI: Beliefs Desires Intentions• Autonomous, Flexible, Social• Goal-Oriented• Partial Description of Human AgentsPartial Description of Human Agents• Full Formal Description of SW Agents



The i* Modeling Framework

• Developed by Eric Yu• Distributed Intentionality (Actors with Goals) • 2 Model Types• 2 Model Types

– Strategic Dependency (SD)• Intentional, strategic relationships among actors• Actor Diagram

– Strategic Rationale (SR)• Rationale behind dependenciesp• Analysis of alternatives & dependency fulfillment• Goal Diagram


gR. Klamma, RWTH Aachen 5

i* - Syntax Element Overview

• ActorActor• Actor Associations• Goal, Softgoal, Task, Resource, • Links• Links

– Strategic Dependency (SD)– Strategic Rationale (SR)

• Decomposition• Means-Ends• Contributions



Actor, Agent, Role, Position

• Actor– Abstract representation for active entity– Carries out actions to reach goals

• Agent– Concrete manifestation of actor

/S f– Human/Software

• RoleDomain specific behaviour of actor– Domain-specific behaviour of actor

– Played by actor

• PositionPosition– Covers set of roles– Occupied by agent


p y g


SD - Actor Associations

• 6 Types:plays– plays

– occupies– covers– is ais a– is Part Of

is Instance– is Instance



SD - Strategic Dependencies

Four Dependency Types:Four Dependency Types:• Goal (fulfill) • Task (complete)• Softgoal (fulfill) • Resource (provide)



SD - Vulnerability

• Vulnerability implied with dependencies• 3 Degrees of strength

– Open: slightly affects dependerOpe s g y a ec s depe de– Committed: causes action in depender – Critical: causes all depender actions to fail


Critical: causes all depender actions to failR. Klamma, RWTH Aachen 10

SR – Actor Boundaries

• Intentional boundary of actory• Elements within explicitly desired by actor

A t t d d th ’ i t ti• Actor must depend on others’ intentions• Actor is depended upon by others



p p y

SR – Means-Ends Links

• Relationship between – an endan end– a means for attaining end

E d G l ( h t)• End: Goal (what)• Means: Task (how)



( )

SR – Decomposition Links

Task Goal Decomposition: Subgoal• Task-Goal Decomposition: Subgoal• Task-Task Decomposition: Subtask• Task-Resource Decomposition: ResourceFor• Task-Softgoal Decomposition: SoftgoalFor


as So tgoa eco pos t o So tgoa oR. Klamma, RWTH Aachen 13

SR – Contribution Links

• contribution to fulfillment of softgoals• contribution to fulfillment of softgoals• 9 Types:

MakeSome+

BreakSome

UnknownAnd Some+

Help Some- Hurt

And Or



SJTU Peer Teaching Scenario (SD)



SJTU Peer Teaching Scenario (SR)



Further Information – I* Wiki

• Available at http://istar.rwth-aachen.dep• Tutorials & Modeling Guidelines

T l• Tools• Publications categorized by domaing y

– Requirements EngineeringTrust in Multi Agent Systems– Trust in Multi Agent Systems

– Variability and Personalization– Knowledge Management



i* Modeling of Agent-based RE Processes – A Basic Tutorial

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