1. Rational Requirements Management with Use Cases v5.5 Copyright © 1998-2000 Rational Software, all rights reserved 1 Requirements Management with Use Cases Module 2 Introduction to RMUC

2. Rational Requirements Management with Use Cases v5.5 Copyright © 1998-2000 Rational Software, all rights reserved 2 0 - About This Course 1 - Best Practices of Software Engineering 2 - Introduction to RMUC 3 - Analyzing the Problem 4 - Understanding Stakeholder Needs 5 - Defining the System 6 - Managing the Scope of the System 7 - Refining the System Definition 8 - Managing Changing Requirements 9 - Requirements Across the Product Lifecycle RMUC: Course Outline

3. Rational Requirements Management with Use Cases v5.5 Copyright © 1998-2000 Rational Software, all rights reserved 3 Introduction to RMUC: Overview Problem Solution Space Problem Space Needs Features Software Requirements Test Procedures DesignUser Docs The Product To Be Built Traceability

4. Rational Requirements Management with Use Cases v5.5 Copyright © 1998-2000 Rational Software, all rights reserved 4 Why Are We Here? The GOAL is to deliver quality products on time and on budget which meet the customer’s real needs.

5. Rational Requirements Management with Use Cases v5.5 Copyright © 1998-2000 Rational Software, all rights reserved 5 Agreement on What the System Should Do The Goal Surrogate Goal Requirements Verification Customer User Community Requirements System To Be Built Adapted from Al Davis

6. Rational Requirements Management with Use Cases v5.5 Copyright © 1998-2000 Rational Software, all rights reserved 6 Definitions: Requirements and Their Management  A requirement is a condition or capability to which the system must conform  Requirements management is a systematic approach to  Eliciting, organizing, and documenting the requirements of the system, and  Establishing and maintaining agreement between the customer/user and the project team on the changing requirements of the system

7. Rational Requirements Management with Use Cases v5.5 Copyright © 1998-2000 Rational Software, all rights reserved 7 Requirements Specifications User Documentation Specifications Design Specifications Test Specifications Use-Case Model Supplementary Specifications Vision Document Features Software Requirements Needs

8. Rational Requirements Management with Use Cases v5.5 Copyright © 1998-2000 Rational Software, all rights reserved 8 Linking Requirements

9. Rational Requirements Management with Use Cases v5.5 Copyright © 1998-2000 Rational Software, all rights reserved 9 What Factors Contribute to Project Success? Standish Group, ‘95 (www.standishgroup.com) Project Success Factors  Only 16% of projects completed on time and on budget (all companies)  9% (large companies)  28% (small companies)  53% of projects over-ran their original estimates  Average overrun: 189% (+$59 billion)  31% of projects canceled before completion ($81 billion) However... Why are these results so bad? 1) User Involvement 2) Executive Management Support 13.9% 3) Clear Statement of Requirements 11.8% 15.9%

10. Rational Requirements Management with Use Cases v5.5 Copyright © 1998-2000 Rational Software, all rights reserved 10 What Factors Contribute to Project Failure? Standish Group, ‘95 (www.standishgroup.com) Project Impaired (canceled) Factors Project Challenged (over-runs) Factors

11. Rational Requirements Management with Use Cases v5.5 Copyright © 1998-2000 Rational Software, all rights reserved 11 How Can a Use-Case Model Help? The most important role of a use-case model is to communicate the system’s functionality and behavior to the customer or end user.  Models the system to be built  Ways to use the system (“use cases”)  Surroundings: who interacts with the system (“actors”)  Provides unifying thread for system development  Goal is for the system to meet customer requirements  The same use-case model is used in Requirements, Analysis & Design, and Test

12. Rational Requirements Management with Use Cases v5.5 Copyright © 1998-2000 Rational Software, all rights reserved 12  An actor represents an external entity that interacts with the system.  A use case defines a sequence of actions performed by a system that yields an observable result of value to an actor. Actor Use Case Use-Case Model: Major Concepts

13. Rational Requirements Management with Use Cases v5.5 Copyright © 1998-2000 Rational Software, all rights reserved 13 What Is a Use-Case Model? A Sample System Bank Consortium Customer Deposit Funds Withdraw Cash An Automated Teller Machine (ATM) Transfer Funds Cashier A model of what the system is supposed to do (use cases), and the system's surroundings (actors). Maintain ATM Maintenance Crew

14. Rational Requirements Management with Use Cases v5.5 Copyright © 1998-2000 Rational Software, all rights reserved 14 A Use-Case Model Is Mostly Text! Use-Case-Model Survey - survey description - list of all actors - list of all use cases Withdraw Cash - brief description - flow of events Transfer Funds - brief description - flow of events Deposit Funds - brief description - flow of events Maintain ATM - brief description - flow of events Customer Transfer Funds Deposit Funds An ATM Maintain ATM Withdraw Cash Bank ConsortiumCashierMaintenance Crew

15. Rational Requirements Management with Use Cases v5.5 Copyright © 1998-2000 Rational Software, all rights reserved 15 1. Read the Requested Features and User Interface sketch for the Sample (ATM) System on the following two slides. 2.Now, look at Sample Use-Case Model in the Handouts:  Use-Case-Model Survey for ATM in Handout UC 1  Use-Case Report for Withdraw Cash in Handout UC 3.1  Don’t worry about understanding everything in the reports. Just observe the structure and content. Exercise: A Sample Use-Case Model UC1 and UC3.1

16. Rational Requirements Management with Use Cases v5.5 Copyright © 1998-2000 Rational Software, all rights reserved 16 Sample System: Requested Features  Design the software for an automated teller machine (ATM). The ATM requests necessary information from the bank by communicating with the bank’s computer system.  The ATM accepts a cash card, interacts with the user via a display and a key pad, communicates with the bank computer to carry out the transaction, receives and dispenses cash, and prints out a receipt.  A user should be able to withdraw cash, transfer funds between two of her accounts, and deposit to an account.  When a transaction is finished, the card is ejected.  The system requires appropriate record keeping and security provisions.

17. Rational Requirements Management with Use Cases v5.5 Copyright © 1998-2000 Rational Software, all rights reserved 17 123 456 789 0 ReadyUndoHelp Cash Dispenser Deposit Input Printer Card Reader Sample System: Sketch of User Interface

18. Rational Requirements Management with Use Cases v5.5 Copyright © 1998-2000 Rational Software, all rights reserved 18 Benefits of a Use-Case Model  Use cases are concise, simple, and understandable by a wide range of stakeholders  Use terminology that customers and users understand  Verify developer understanding  Use cases give context for requirements  Identify the role of the users of the system  Identify system interfaces  Put system requirements in logical sequences  Help verify that all requirements are captured  Use cases facilitate agreement with the customer on system requirements

19. Rational Requirements Management with Use Cases v5.5 Copyright © 1998-2000 Rational Software, all rights reserved 19 Customer A Use-Case Model Helps with ‘Scope Creep’  The customer is aware there is a change to the use-case model  Makes the cost impact visible to the customer I’ll need a new use case and change some existing use cases...

20. Rational Requirements Management with Use Cases v5.5 Copyright © 1998-2000 Rational Software, all rights reserved 20 The High Cost of Requirement Errors Relative Cost to Repair Errors: When introduced vs. when repaired 20 0.5 1 2 5.1-.2 Requirements Time Design Coding Unit Test Acceptance Test Maintenance Stage “All together, the results show as much as a 200:1 cost ratio between finding errors in the requirements and maintenance stages of the software lifecycle.” Boehm 1988 Average cost ratio 14:1 Grady 1989 The 1-10-100 Rule

21. Rational Requirements Management with Use Cases v5.5 Copyright © 1998-2000 Rational Software, all rights reserved 21 Involve the Whole Team in Requirements  Developers, Testers, Writers  Help develop requirements management practices  Monitor adherence to these practices  Verify elicitation process and outcomes  Help document and communicate requirements  Participate in requirements reviews and customer walkthroughs  Review traceability outcomes  Verify quality and completeness  Participate in or chair a CCB (Change Control Board)

22. Rational Requirements Management with Use Cases v5.5 Copyright © 1998-2000 Rational Software, all rights reserved 22 Review: Introduction to RMUC 1. What is our goal? 2. How can we “measure” quality?  What are the FURPS categories of requirements?  What categories within each of these apply to your product? 3. Why is it important to establish a baseline? How is it done? 4. How can a Use-Case Model help in developing our project? 5. What does the “1-10-100 Rule” tell us about finding defects? 6. What are some ways to involve the development team early?