1. PowerPoint Presentation for Dennis, Wixom, & Roth Systems Analysis and Design, 3rd Edition Copyright 2006 © John Wiley & Sons, Inc. All rights reserved. 5 - 1 Systems Analysis and Design Third Edition Alan Dennis, Barbara Haley Wixom, and Roberta Roth John Wiley & Sons, Inc. Slides by Candace S. Garrod Red Rocks Community College

2. PowerPoint Presentation for Dennis, Wixom, & Roth Systems Analysis and Design, 3rd Edition Copyright 2006 © John Wiley & Sons, Inc. All rights reserved. 5 - 2 Use Case Analysis

3. PowerPoint Presentation for Dennis, Wixom, & Roth Systems Analysis and Design, 3rd Edition Copyright 2006 © John Wiley & Sons, Inc. All rights reserved. 5 - 3 Key Ideas Use cases are a text-based method of describing and documenting complex processes Use cases add detail to the requirements outlined in the requirement definition Systems analysts work with users to develop use cases Systems analysts develop process and data models later based on the use cases

4. PowerPoint Presentation for Dennis, Wixom, & Roth Systems Analysis and Design, 3rd Edition Copyright 2006 © John Wiley & Sons, Inc. All rights reserved. 5 - 4 Use Cases

5. PowerPoint Presentation for Dennis, Wixom, & Roth Systems Analysis and Design, 3rd Edition Copyright 2006 © John Wiley & Sons, Inc. All rights reserved. 5 - 5 Roles of Use Cases A use case is a set of activities that produce some output result Describes how the system reacts to an event that triggers the system Trigger -- event that causes the use case to be executed Event-driven modeling – everything in the system is a response to some triggering event

6. PowerPoint Presentation for Dennis, Wixom, & Roth Systems Analysis and Design, 3rd Edition Copyright 2006 © John Wiley & Sons, Inc. All rights reserved. 5 - 6 Role of Use Cases All possible responses to the event are documented Use cases are helpful when the situation is complicated

7. PowerPoint Presentation for Dennis, Wixom, & Roth Systems Analysis and Design, 3rd Edition Copyright 2006 © John Wiley & Sons, Inc. All rights reserved. 5 - 7 Elements of a Use Case Basic information Name, number and brief description Trigger – event that causes the use case to being External trigger – some from outside the system Temporal triggers – time-based occurrences Viewpoint of the use cases should be consistent Major inputs and outputs Sources and destinations Goal is to be all inclusive Details Steps performed and the data inputs and outputs

8. Sample Use Case

9. PowerPoint Presentation for Dennis, Wixom, & Roth Systems Analysis and Design, 3rd Edition Copyright 2006 © John Wiley & Sons, Inc. All rights reserved. 5 - 9 Building Use Cases

10. PowerPoint Presentation for Dennis, Wixom, & Roth Systems Analysis and Design, 3rd Edition Copyright 2006 © John Wiley & Sons, Inc. All rights reserved. 5 - 10 Process of Developing Use Cases Identify the major use cases Identify the major steps within each use case Identify elements within steps Confirm the use case Cycle through the above steps iteratively

11. Step 1: Identify the major use cases ActivitiesTypical Questions Asked Start a use case form for each use case If more than nine, group into packages Ask who, what, and where about the tasks and their inputs and outputs: What are the major tasks performed? What triggers this task? What tells you to perform this task? What information/forms/reports do you need to perform this task? Who gives you these information/forms/reports? What information/forms/reports does this produce and where do they go?

12. PowerPoint Presentation for Dennis, Wixom, & Roth Systems Analysis and Design, 3rd Edition Copyright 2006 © John Wiley & Sons, Inc. All rights reserved. 5 - 12 Sample List of Events-Actions Based on Requirements Definition

13. Step 2: Identify the major steps within each use case ActivitiesTypical Questions Asked For each use case, fill in the major steps needed to process the inputs and produce the outputs Ask how about each use case: How do you produce this report? How do you change the information on the report? How do you process forms? What tools do you use to do this step (e.g., on paper, by email, by phone)?

14. Step 3: Identify elements within steps ActivitiesTypical Questions Asked For each step, identify its triggers and its inputs and outputs Ask how about each step How does the person know when to perform this step? What forms/reports/data does this step produce? What forms/reports/data does this step need? What happens when this form/report/data is not available?

15. Step 4: Confirm the use case ActivitiesTypical Questions Asked For each use case, validate that it is correct and complete Ask the user to execute the process using the written steps in the use case – that is, have the user role-play the use case

16. PowerPoint Presentation for Dennis, Wixom, & Roth Systems Analysis and Design, 3rd Edition Copyright 2006 © John Wiley & Sons, Inc. All rights reserved. 5 - 16 CD SELECTIONS

17. PowerPoint Presentation for Dennis, Wixom, & Roth Systems Analysis and Design, 3rd Edition Copyright 2006 © John Wiley & Sons, Inc. All rights reserved. 5 - 17 CD SELECTIONS

18. PowerPoint Presentation for Dennis, Wixom, & Roth Systems Analysis and Design, 3rd Edition Copyright 2006 © John Wiley & Sons, Inc. All rights reserved. 5 - 18 CD SELECTIONS

19. PowerPoint Presentation for Dennis, Wixom, & Roth Systems Analysis and Design, 3rd Edition Copyright 2006 © John Wiley & Sons, Inc. All rights reserved. 5 - 19 CD SELECTIONS

20. PowerPoint Presentation for Dennis, Wixom, & Roth Systems Analysis and Design, 3rd Edition Copyright 2006 © John Wiley & Sons, Inc. All rights reserved. 5 - 20 Summary Use cases contain all the information needed for process modeling, but are easier for users to comprehend Use cases are created in an iterative cycle of steps until they are considered accurate and complete

21. PowerPoint Presentation for Dennis, Wixom & Tegardem Systems Analysis and Design Copyright 2001 © John Wiley & Sons, Inc. All rights reserved. Slide 21 Systems Analysis and Design with UML Version 2.0, Second Edition Alan Dennis, Barbara Wixom, and David Tegarden Chapter 6: Functional Modeling John Wiley & Sons, Inc. Copyright 2005

22. PowerPoint Presentation for Dennis, Wixom & Tegardem Systems Analysis and Design Copyright 2001 © John Wiley & Sons, Inc. All rights reserved. Slide 22 Objectives ■ Understand the rules and style guidelines for activity diagrams. ■ Understand the rules and style guidelines for use cases and use case diagrams. ■ Understand the process used to create use cases and use case diagrams. ■ Be able to create functional models using activity diagrams, use cases, and use case diagrams. ■ Become familiar with the use of use case points.

23. PowerPoint Presentation for Dennis, Wixom & Tegardem Systems Analysis and Design Copyright 2001 © John Wiley & Sons, Inc. All rights reserved. Slide 23 Business Process Modeling with Activity Diagrams Elements of an Activity Diagram Guidelines for Creating Activity Diagrams

24. PowerPoint Presentation for Dennis, Wixom & Tegardem Systems Analysis and Design Copyright 2001 © John Wiley & Sons, Inc. All rights reserved. Slide 24 BPM With Activity Diagrams A number of activities support a business process across several departments Activity diagrams model the behavior in a business process Sophisticated data flow diagrams Addresses Parallel concurrent activities and complex processes

25. PowerPoint Presentation for Dennis, Wixom & Tegardem Systems Analysis and Design Copyright 2001 © John Wiley & Sons, Inc. All rights reserved. Slide 25 Activity Diagram Example

26. PowerPoint Presentation for Dennis, Wixom & Tegardem Systems Analysis and Design Copyright 2001 © John Wiley & Sons, Inc. All rights reserved. Slide 26 Creating Activity Diagrams 1. Since an activity diagram can be used to model any kind of process, you should set the context or scope of the activity being modeled. Once you have determined the scope, you should give the diagram an appropriate title. 2. You must identify the activities, control flows, and object flows that occur between the activities. 3. You should identify any decisions that are part of the process being modeled. 4. You should attempt to identify any prospects for parallelism in the process. 5. You should draw the activity diagram.

27. PowerPoint Presentation for Dennis, Wixom & Tegardem Systems Analysis and Design Copyright 2001 © John Wiley & Sons, Inc. All rights reserved. Slide 27 USE-CASE DESCRIPTIONS

28. PowerPoint Presentation for Dennis, Wixom & Tegardem Systems Analysis and Design Copyright 2001 © John Wiley & Sons, Inc. All rights reserved. Slide 28 Key Ideas A use case illustrates the activities that are performed by users of a system. Use cases are logical models -- they describe the activities of a system without specifying how the activities are implemented.

29. PowerPoint Presentation for Dennis, Wixom & Tegardem Systems Analysis and Design Copyright 2001 © John Wiley & Sons, Inc. All rights reserved. Slide 29 What are Use-Case Descriptions? Describe basic functions of the system What the user can do How the system responds Use cases are building blocks for continued design activities.

30. PowerPoint Presentation for Dennis, Wixom & Tegardem Systems Analysis and Design Copyright 2001 © John Wiley & Sons, Inc. All rights reserved. Slide 30 How Are Use-Cases Created? Two steps: Write text-based case descriptions Translate descriptions into diagrams Describes one and only one function, but may have multiple paths. Developed working with users for content.

31. PowerPoint Presentation for Dennis, Wixom & Tegardem Systems Analysis and Design Copyright 2001 © John Wiley & Sons, Inc. All rights reserved. Slide 31 Types of Use-Cases Overview versus detail ■ The use case represents an important business process. ■ The use case supports revenue generation or cost reduction. ■ Technology needed to support the use case is new or risky and therefore will require considerable research. Essential versus real

32. PowerPoint Presentation for Dennis, Wixom & Tegardem Systems Analysis and Design Copyright 2001 © John Wiley & Sons, Inc. All rights reserved. Slide 32 Elements of a Use-Case Description Use Case Name:ID:Importance Level: Primary Actor:Use Case Type: Stakeholders and Interests: Brief Description: Trigger: Relationships: (Association, Include, Extend, Generalization) Normal Flow of Events: Subflows: Alternate/Exceptional Flows:

33. PowerPoint Presentation for Dennis, Wixom & Tegardem Systems Analysis and Design Copyright 2001 © John Wiley & Sons, Inc. All rights reserved. Slide 33 Guidelines for Creating Use-Case Descriptions Write each step in “SVDPI” form Clarify initiator and receivers of action Write from independent observer perspective Write at same level of abstraction Ensure a sensible set of steps Apply KISS principle liberally Write repeating instructions after the set of steps to be repeated.

34. PowerPoint Presentation for Dennis, Wixom & Tegardem Systems Analysis and Design Copyright 2001 © John Wiley & Sons, Inc. All rights reserved. Slide 34 Your Turn How would you make requirements gathering (interviews, questionnaires, observation, and document analysis) more effective by knowing that eventually you will be creating use-case descriptions and diagrams?

35. PowerPoint Presentation for Dennis, Wixom & Tegardem Systems Analysis and Design Copyright 2001 © John Wiley & Sons, Inc. All rights reserved. Slide 35 USE-CASE DIAGRAMS

36. Syntax for Use-Case Diagram

37. PowerPoint Presentation for Dennis, Wixom & Tegardem Systems Analysis and Design Copyright 2001 © John Wiley & Sons, Inc. All rights reserved. Slide 37 The Use-Case Diagram for Appointment System

38. PowerPoint Presentation for Dennis, Wixom & Tegardem Systems Analysis and Design Copyright 2001 © John Wiley & Sons, Inc. All rights reserved. Slide 38 Use-Case Diagram with Specialized Actor

39. Extend and Include Relationships

40. PowerPoint Presentation for Dennis, Wixom & Tegardem Systems Analysis and Design Copyright 2001 © John Wiley & Sons, Inc. All rights reserved. Slide 40 CREATING USE-CASE DESCRIPTIONS AND USE- CASE DIAGRAMS

41. PowerPoint Presentation for Dennis, Wixom & Tegardem Systems Analysis and Design Copyright 2001 © John Wiley & Sons, Inc. All rights reserved. Slide 41 Major Steps in Writing Use-Cases Case Diagrams Identify the major use-cases Expand the major use-case Confirm the major use-cases Create the use-case diagram

42. PowerPoint Presentation for Dennis, Wixom & Tegardem Systems Analysis and Design Copyright 2001 © John Wiley & Sons, Inc. All rights reserved. Slide 42 Identifying the Major Use- Cases Identify the system’s boundaries List the primary actors List the goals of each primary actor Identify and write the major use- cases Carefully review use-cases

43. Writing Effective Use-Case Descriptions

44. PowerPoint Presentation for Dennis, Wixom & Tegardem Systems Analysis and Design Copyright 2001 © John Wiley & Sons, Inc. All rights reserved. Slide 44 Expand the Major Use- Cases Choose one major use-case to expand Fill in details on the use-case template Fill in the steps of the normal flow of events Normalize the size of each step Describe alternate or exceptional flows Simplify and organize as necessary

45. PowerPoint Presentation for Dennis, Wixom & Tegardem Systems Analysis and Design Copyright 2001 © John Wiley & Sons, Inc. All rights reserved. Slide 45 Confirm the Major Use Cases Review the current set Consider semantics and syntax Helpful to involve the users Iterate the entire set of steps until all use cases are defined

46. PowerPoint Presentation for Dennis, Wixom & Tegardem Systems Analysis and Design Copyright 2001 © John Wiley & Sons, Inc. All rights reserved. Slide 46 Create the Use-Case Diagram Start with system boundary Place elements in order to be easy to read Place actors on the diagram Conclude by connecting actors to use cases by lines

47. PowerPoint Presentation for Dennis, Wixom & Tegardem Systems Analysis and Design Copyright 2001 © John Wiley & Sons, Inc. All rights reserved. Slide 47 Selecting the Appropriate Techniques Interviews JAD Questionnaires Document Observation Analysis Type of As-Is As-Is As-Is As-Is As-Is Information Improve. Improve. Improve. To-Be To-Be Depth of High High Medium Low Low Information Breadth of Low Medium High High Low Information Integration Low High Low Low Low of Info. User Medium High Low Low Low Involvement Cost Medium Low- Low Low Low- Medium Medium

48. PowerPoint Presentation for Dennis, Wixom & Tegardem Systems Analysis and Design Copyright 2001 © John Wiley & Sons, Inc. All rights reserved. Slide 48 Refining Project Size with Case Points Create essential use cases and use case diagram Determine Unadjusted Actor Weighting Table Obtain Unadjusted Use Case Weight Total Compute value of Unadjusted Use Case Points

49. PowerPoint Presentation for Dennis, Wixom & Tegardem Systems Analysis and Design Copyright 2001 © John Wiley & Sons, Inc. All rights reserved. Slide 49 Identify the major use-cases Expand the major use-case Confirm the major use-cases Create the use-case diagram

50. PowerPoint Presentation for Dennis, Wixom & Tegardem Systems Analysis and Design Copyright 2001 © John Wiley & Sons, Inc. All rights reserved. Slide 50 Your Turn Create a set of use cases for campus housing. Consider the steps in registering for campus housing, in being assigned to a particular unit, to being matched with roommates, to moving in.

51. PowerPoint Presentation for Dennis, Wixom & Tegardem Systems Analysis and Design Copyright 2001 © John Wiley & Sons, Inc. All rights reserved. Slide 51 Expanding the Domain Additional resources regarding use-cases and many other object-oriented development topics can be found at: http://www.omg.org

52. PowerPoint Presentation for Dennis, Wixom & Tegardem Systems Analysis and Design Copyright 2001 © John Wiley & Sons, Inc. All rights reserved. Slide 52 Summary Use-case descriptions are the basis for further analysis and design. They are created based on 7 guidelines and 13 steps. Use-case diagrams present a graphical overview of the main functionality of a system.

53. PowerPoint Presentation for Dennis, Wixom, & Roth Systems Analysis and Design, 3rd Edition Copyright 2006 © John Wiley & Sons, Inc. All rights reserved. 5 - 53 Copyright © 2006 John Wiley & Sons, Inc. All rights reserved. Reproduction or translation of this work beyond that permitted in Section 117 of the 1976 United States Copyright Act without the express written permission of the copyright owner is unlawful. Request for further information should be addressed to the Permissions Department, John Wiley & Sons, Inc. The purchaser may make back-up copies for his/her own use only and not for redistribution or resale. The Publisher assumes no responsibility for errors, omissions, or damages, caused by the use of these programs or from the use of the information contained herein.