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Strategic Actor Relationships Strategic Actor Relationships

Modelling with Modelling with i*i*

Eric YuUniversity of Toronto

December 13-14, 2001IRST, Trento, Italy

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Agenda Session 1 – Introduction

December 13, 14:30-16:30

• Background and Motivations• Basic concepts

– The Strategic Dependency Model– The Strategic Rationale Model

• More Examples– Software process modelling– Software architecture– Business redesign

• Homework

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Agenda Session 2 – Workshop

December 14, 14:30-16:30

• Example– Intellectual Property Management

• Discussions of Exercises

References– http://www.cs.toronto.edu/km/istar– http://www.cs.toronto.edu/km/OME– http://www.fis.utoronto.ca/~yu

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Agent-Oriented Software Engineering: A Requirements Engineering Perspective

Eric YuUniversity of TorontoSeptember 2001

IRST Seminar

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Agent-Oriented Software

•Situated sense the environment and perform actions that change the

environment

•Autonomous have control over their own actions and internal states can act without direct intervention from humans

•Flexible responsive to changes in environment, goal-oriented, opportunistic,

take initiatives

•Social interact with other artificial agents and humans to complete their

tasks and help others

Jennings, Sycara, Wooldridge (1998) A Roadmap of Agent Research & Development. Autonomous Agents & Multi-Agent Systems journal.

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But why Agent Orientation?

•The “world” (application environment) has become more distributed, autonomous, networked… I.e. the agent properties are being found in the world. E.g. E-commerce, e-health, e-learning, groupwork, kn mgt

•Question is: how to make the software systems meet these desired properties (in the world)

•That’s the job of RE (and SE). But previously, no way of expressing these properties. RE languages need to be social, intentional. Most AOSE methodologies focus the system, not on

relationship to the world

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Requirements Engineering

• relationship between system and environment. Bubenko (1980), Greenspan (1982), Jackson (1983)…

•Traditional focus: consistency, completeness, … e.g., “Three Dimensions of RE” Pohl (1993)

• informal -> formal (representation)• opaque -> complete (specification)• personal view -> common view (agreement)

Suitable for a more stable, non-distributed world

•Recent: goals, scenarios, agents See overview in van Lamsweerde (ICSE 2000)

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Ontologies for Modelling

• Static Ontologies

• Dynamic Ontologies

• Intentional OntologiesIntentional Ontologies

• Social OntologiesSocial Ontologies

[J. Mylopoulos CAiSE 97 Keynote]

• Most current conceptions and models of information systems are based on static and dynamic ontologies.• business process models• workflow models• enterprise models• … UML

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A typical process model

… but we need deeper understanding!

Automobile insurance claims example

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… a deeper understanding about processes

• Car owner wants car to be repaired• Insurance company wants to minimize

claims payout• Car owner wants fair appraisal of repairs• Insurance agent wants to maintain good

customer relations

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Modelling Strategic Actor Relationships and Rationales

- the i* modelling framework

• – have goals, beliefs, abilities, commitments– depend on each other for goals to be

achieved, tasks to be performed, resources to be furnished

– are semi-autonomous -- not fully knowable / controllable

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Strategic Dependency Relationship

Actor A

I want …

Actor B

I can …

D DCar Be Repaired

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i* objectives, premises, key concepts

• Actors are semi-autonomous, partially knowable

• Strategic actors, intentional dependencies

• have choice, reasons about alternate means to ends

means-endsalternatives

D D

wants andabilities

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i* modeling

1. explicit intentionality goals

2. implicit intentionality agents

functionaldecomposition

means-endsalternatives

wants andabilities

inputsoutputs

D D

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Development-World model refers to and reasons about…

Operational-World models

Alt-1 Alt-2 To-beAs-is

Strategic Rationale ModelStrategic Rationale Model

Strategic Dependency ModelsStrategic Dependency Models

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Softgoal Operationalizations: Contribution Relationship

Side-effects to softgoals: Correlation Relationship

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Analysis and Design Support

• opportunities and vulnerabilities– ability, workability, viability, believability– insurance, assurance, enforceability – node and loop analysis

• design issues– raising, evaluating, justifying, settling– based on qualitative reasoning

[Chung Nixon Yu Mylopoulos (2000) Non-Functional Requirements in Software Engineering. Kluwer Academic Publishers.]

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Sample i* representation for an actor (in

Telos) TELL Class Physician IN PositionClass ISA ProfessionalPosition WITH

resDepends, committedTo fs: FeeForTreatment WITH dependee cm:ClaimsManager end

goalDepended, commitsTo td: $Treated(p.injury)$ WITH depender p:Patient end

taskDepends, committedTo tm: TakeMedication(p.med) WITH dependee p:Patient end

covers tp: TreatingPatient(p) bi: Billing(p.insurCo)

integrityConstraint correctClaimsManager: $cm=p.insurCo.claimsMgr$

end

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The Strategic Rationale Model - a partial schema

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Another Example:

Meeting Scheduler

From: E. Yu. Towards Modelling and Reasoning Support for Early-Phase Requirements Engineering    3rd IEEE Int. Symp. on Requirements Engineering (RE'97) Jan. 6-8, 1997, Washington D.C., USA. pp. 226-235.

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“Strategic Dependency” Model

Meeting Scheduling Meeting Scheduling ExampleExample

[Yu RE97]

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Revealing goals, finding alternatives• Ask “Why”, “How”, “How else”

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Scheduling meeting …with meeting scheduler

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“Strategic Rationale” Model with Meeting Scheduler

• SR2