Integrating Use Cases and Organizational Modeling

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Integrating Use Cases andOrganizational Modeling

• Victor Santander Jaelson Castro
• Centro de Informática
• Universidade Federal de Pernambuco UFPE
• Brazil
• jbc_at_cin.ufpe.br

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Outline

• Motivation
• Organizational modeling with i
• Deriving Use Cases from i models
• e-commerce Case Study
• Benefits
• Related and future work

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Motivation

• System development occurs in a context where
  organizational processes are well established
• The need to capture organizational requirements
  to define how the system fulfils the
  organizational goals
• i (Tropos) is well suited to represent
  organizational requirements that occur during the
  early-phase requirements capture
• Organizational requirements must be related to
  functional requirements

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Our Proposal
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Organizational Modeling

• Bubenko (1993), i (Yu 1995), GRL, Tropos
• i provides understanding of the reasons (Why)
  that underlie system requirements, focuses on
  strategic actor relationships
• The Strategic Dependency Model (SD)
• Actors and dependencies (goal, resource, task,
  softgoal)
• The Strategic Rationale Model (SR)
• Nodes are dependencies defined in the SD and
• Links means-ends and task-decomposition

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The Strategic Dependency Model
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The Strategic Rationale Model
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Use Cases

• Use cases were meant for Functionality
• Can organizational models assist requirements
  engineers to develop use cases?

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Integrating i and Use Cases
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Deriving Use Cases from Organizational Modeling

• Guidelines are required
• Overview
• Discovering system actors
• Discovering use cases for the actors
• Describing flow of events (scenarios)

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Discovering System Actors

• 1º Step Discovering System Actors.
• Guideline 1every actor in i should be
  considered as a possible Use Case actor Ex
  Customer actor
• Guideline 2 actors must be external (not the
  software system)
• Guideline 3 dependencies must be relevant from
  the point of view of the intended system
• Guideline 4 i IS-A ? Use Case Actor
  generalization

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Discovering Use Cases for the Actors

• 2º Step Discovering Use Cases for the Actors.
• Guideline 5 for each discovered system actor,
  observe all their dependencies as dependee

• Guideline 5.1 goal dependencies

Table 1. SD Models X Use Cases.

• Guideline 5.2 task dependencies
• Place Order task ? Place Order Use Case for the
  Customer actor

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Discovering Use Cases for the Actors

• Guideline 5.3 resources dependencies
• Ex Internet Services ? Internet Services use
  case for the Telecom Cpy actor.
• Guideline 5.4 sofgoal dependencies
• Ex Increase Market Share can be mapped into a
  non functional requirement for Place Order use
  case .
• Guideline 6 Consider dependencies of the
  intended software system as dependee
• Ex Processed Internet Orders? Processed Internet
  Orders Use Case for the Media Shop actor.

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Discovering Use Cases for the Actors

• Guideline 7 classify each use case according to
  the type associated to its goal (Cockburn 2000)
• business goal the media shop wishes to increase
  market shares
• summary goal increase market shares by using an
  e-commerce application
• user goal "the customer wishes to place order
• subfunction goalthe customer browse catalogue

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Discovering and Describing Scenarios of Use Cases

• 3º Proposal Step Discovering and Describing
  Scenarios of Use Cases.
• Guideline 8 analyze each actor and their
  relationships in the Strategic Rationale (SR)
  model.
• means-ends ? exceptional flow of events
• task-decomposition ? use case description steps
  (main flow of events)
• Ex Shopping Cart task decomposition.

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Case Study

• Medi_at_ system
• 1st step - Discovering System Actors
  (G1,G2,G3,G4)
•      Media Shop, Media Supplier, Bank Cpy,
  Telecom Cpy and Customer
• 2º Step - Discovering Use Cases for the Actors
  (G5)

Table 3. Gathered information from SD Models to
derive Use Cases for the Medi_at_ System.
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Case Study

• Guideline 6
• Processed Internet Orders Goal - gt Processed
  Internet Orders Use Case for the Media Shop
  actor
• Guideline 7

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Place Order Use Case Main flow of events
(Guideline 8)

• Use Case Goal Place Order
• Level User Goal (see guideline 7)
• Actor Customer
• Primary Scenario
• 1. The Use Case begins with the Customer
  selecting an available item
• 2. The Customer adds item to the Shopping Cart
• 3. The Customer proceeds to check out
• 4. The system gets customers identification
  detail through Internet and closes the order.
• Extends
• 1.a the customer pre-orders an unavailable item
• 4.a the customer chooses to provide
  identification details by classic communication.

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Use Cases Diagram for the Medi_at_ System.
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Benefits of our approach

• GORE explicitly capture why and how relationships
  in terms of goals
• Dealing with dynamic business
• Cure for some Use Case pitfalls (S. Lilly)
• Use cases are written from the systems (not the
  actors) point of view ? i dependencies
• Too many Use Cases ? essential use cases for the
  intended system
• The customer doesn't understand the use cases ?
  integration of engineers and customers during
  GORE
• Observing the actors goal in relation to the
  system-to-be is a way of clarifying requirements

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Related Work

• The requirements-driven Tropos framework (RE01)
• The integration of i and pUML diagrams (RE01)
• ScenIC method (Potts),
• GBRAM method (Anton)
• LÉcritoire (Rolland)

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Future Works

• To deal with non-functional requirements
  (softgoals in i)
• Improve heuristics
• More case studies
• Tool support

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Perguntas?
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Obrigado!

• Jaelson Castro
• jbc_at_cin.ufpe.br