www.wileyeurope.com/college/van lamsweerde part 2: building system models for re © 2009 john wiley...

www.wileyeurope .com/college/van lamsweerde Part 2: Building System Models for RE © 2009 John Wiley and Sons

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Part 2:

Building System Models for RE

Introduction

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RE activities require focus and structure

A recurrent problem ...

– focusing, structuring elicitation sessions & artefacts (Chap.2)

– identifying items at common level of granularity for comparison, evaluation (Chap.3)

– structuring large, complex specifications (Chap.4)

– focusing inspection, validation, verification on structured specs (Chap.5)

– identifying change units, granularities of traceable items, derivation links for reqs evolution (Chap.6)

Model-drivenModel-driven approach to RE

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Model-Driven RE

Model: – abstract representation of system (as-is or to-be)

– highlights, specifies, inter-relates key system features

Multi-viewMulti-view model:

– different system facets for requirements completeness

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Why models for RE ?

Focus on key aspectskey aspects (abstraction from multiple details)

Provides structurestructure for RE activities– target for what must be elicited, evaluated, specified,

consolidated, modified

– interface among RE activities: produce/consume model items

Facilitates analysisanalysis– support for early detection and fix of errors

Support for understanding, explanation to stakeholders

Basis for making decisions– multiple options made explicit

Basis for generating the requirements document (with tool)

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A goal-oriented approach to model-driven RE

modelingmodeling

generation of RE deliverablesgeneration of RE deliverables

interviews documents

.html

.rtf.pdf.mif

existing systems

analysisanalysis

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Concentrates on solid, replicable RE techniques techniques

Emphasizes model construction, construction, beyond mere use of diagrammatic notations

– heuristic rules, tactics, modeling patterns, bad smells

– UML compliance wherever possible

• UUnified MModeling LLanguage, de facto standards

• Specific diagrams when not supported by UML (e.g. goals)

Based on case studies in a variety of domains

The lectures will summarize book chapters, see details there !

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What models for RE ?

whywhy ??

Goals Goals (Chap. 7, 8)

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What models for RE ?

Risks Risks (Chap.9)

whywhy ??

Goals (Chap. 7, 88)

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What models for RE ?

Conceptual objects Conceptual objects (Chap.10)

on what?on what?

why ?

Risks (Chap.9) Goals (Chap. 7, 8)

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What models for RE ?

AgentsAgents (Chap.11)

on what?

why ?

whowho ??

Goals (Chap. 7, 8) Risks (Chap.9)

Conceptual objects (Chap.10)

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What models for RE ?

Operations Operations (Chap.12)

whatwhat ??

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What models for RE ?

whatwhat ??

Behaviors -Behaviors -Scenarios Scenarios (Chap.13)

Behaviors -Behaviors -State machines State machines (Chap.13)

Operations (Chap.12)

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What models for RE ?

whatwhat ??

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Threats Threats (Chap. 16)Operations (Chap.12)

Behaviors -Scenarios (Chap.13)

Behaviors -State machines (Chap.13)

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Building system models for RE:

more detailed outline

Chap.8: Modeling system objectives with goal diagrams

Chap.9: Risk analysis on goal models

Chap.10: Modeling conceptual objects with class diagrams

Chap.11: Modeling system agents and responsibilities

Chap.12: Modeling system operations

Chap.13: Modeling system behaviors: scenarios and state machines

Chap.14: Integrating multiple system views Integrating multiple system views

Chap.15: A Goal-oriented model building method in action A Goal-oriented model building method in action