PowerPoint PresentationChapter MapAn Introduction to Use-Case ModelingIS Development Project Track RecordUser-Centered Development and Use-Case ModelingBenefits of Use-Case ModelingSystem Concepts for Use-Case ModelingSample Use-Case Model DiagramBasic Use-Case SymbolsFour Types of ActorsUse Case Association RelationshipUse Case Extends RelationshipUse Case Uses RelationshipUse Case Depends On RelationshipUse Case Inheritance RelationshipThe Process of Requirements Use-Case ModelingStep 1: identify Business ActorsSample List of ActorsStep 2: Identify Business Requirements Use CasesSample Context DiagramSample Use-Case GlossarySample Use-Case Glossary (continued)Sample Use-Case Glossary (concluded)Step 3: Construct Use-Case Model DiagramStep 4: Document Business Requirements Use-Case NarrativesSample High-Level Version of a Use-Case NarrativeSample Expanded Version of a Use-Case NarrativeSample Expanded Version of a Use-Case Narrative (cont)Slide 29Use Cases and Project ManagementUse-Case Ranking and Priority MatrixSample Use-Case Ranking and Priority MatrixUse-Case Dependency DiagramSample Use-Case Dependency DiagramIrwin/McGraw-Hill Copyright © 2004 The McGraw-Hill Companies. All Rights reservedWhitten Bentley DittmanSYSTEMS ANALYSIS AND DESIGN METHODS 6th Edition7-17C H A P T E RMODELING SYSTEM REQUIREMENTS WITH USE CASESIrwin/McGraw-Hill Copyright © 2004 The McGraw-Hill Companies. All Rights reservedWhitten Bentley DittmanSYSTEMS ANALYSIS AND DESIGN METHODS 6th Edition7-2Chapter MapIrwin/McGraw-Hill Copyright © 2004 The McGraw-Hill Companies. All Rights reservedWhitten Bentley DittmanSYSTEMS ANALYSIS AND DESIGN METHODS 6th Edition7-3An Introduction to Use-Case Modeling•One of the primary challenges in a system design process is the ability to elicit the correct and necessary system requirements from the stakeholders and specify them in a manner understandable to them so those requirements can be verified and validated.–Data and process models, prototypes, requirement specifications.–Understood by designers but not by users.–Leads to scope creep, schedule creep, cost overruns.The hardest single part of building a software system is deciding precisely what to build. No other part of the conceptual work is a difficult as establishing the detailed technical requirements, including all the interfaces to people, to machines, and to other software systems. No other work so cripples the resulting system if done wrong. No other part is more difficult to rectify later. Fred BrooksIrwin/McGraw-Hill Copyright © 2004 The McGraw-Hill Companies. All Rights reservedWhitten Bentley DittmanSYSTEMS ANALYSIS AND DESIGN METHODS 6th Edition7-4IS Development Project Track RecordSource: The Standish Group International, Inc., “Chaos: A Recipe for Success”canceled before completionOver budget, late, or without needed featuresIrwin/McGraw-Hill Copyright © 2004 The McGraw-Hill Companies. All Rights reservedWhitten Bentley DittmanSYSTEMS ANALYSIS AND DESIGN METHODS 6th Edition7-5User-Centered Development and Use-Case ModelingUser-centered development – a process of systems development based on understanding the needs of the stakeholders and the reasons why the system should be developed.Use-case modeling – the process of modeling a system’s functions in terms of business events, who initiated the events, and how the system responds to those events.–Use-case modeling has roots in object-oriented modeling.–Gained popularity in nonobject development environments because of its usefulness in communicating with users.–Compliments traditional modeling tools.Irwin/McGraw-Hill Copyright © 2004 The McGraw-Hill Companies. All Rights reservedWhitten Bentley DittmanSYSTEMS ANALYSIS AND DESIGN METHODS 6th Edition7-6Benefits of Use-Case Modeling•Provides a tool for capturing functional requirements.•Assists in decomposing system scope into more manageable pieces.•Provides a means of communicating with users and other stakeholders concerning system functionality in a language that is easily understood.•Provides a means of identifying, assigning, tracking, controlling, and management system development activities, especially incremental and iterative development.•Provides an aid in estimating project scope, effort, and schedule.•Provides a baseline for testing in terms of defining test plans and test cases.•Provides a baseline for user help systems and manuals as well as system development documentation.•Provides a tool for requirements traceability.•Provides a starting point for the identification of data objects or entities.•Provides functional specifications for designing user and system interfaces.•Provides a means of defining database access requirements.•Provides a framework for driving the system development project.Irwin/McGraw-Hill Copyright © 2004 The McGraw-Hill Companies. All Rights reservedWhitten Bentley DittmanSYSTEMS ANALYSIS AND DESIGN METHODS 6th Edition7-7System Concepts for Use-Case ModelingUse-case diagram – a diagram that depicts the interactions between the system and external systems and users. –It graphically describes who will use the system and in what ways the user expects to interact with the system.Use-case narrative – a textual description of the business even and how the user will interact with the system to accomplish the task.Use case – a behaviorally related sequence of steps (a scenario), both automated and manual, for the purpose of completing a single business task.–Description of system functions from the perspective of external users in terminology they understand.Irwin/McGraw-Hill Copyright © 2004 The McGraw-Hill Companies. All Rights reservedWhitten Bentley DittmanSYSTEMS ANALYSIS AND DESIGN METHODS 6th Edition7-8Sample Use-Case Model DiagramIrwin/McGraw-Hill Copyright © 2004 The McGraw-Hill Companies. All Rights reservedWhitten Bentley DittmanSYSTEMS ANALYSIS AND DESIGN METHODS 6th Edition7-9Basic Use-Case SymbolsUse case – subset of the overall system functionality–Represented graphically by a horizontal ellipse with the name of the use case appearing above, below, or inside the ellipse.Actor – anything that needs to interact with the system to exchange information. –Could be a human, an organization, another information system, an external device, or even time. Temporal event – a system event triggered by time.–The actor is time.Irwin/McGraw-Hill