Team Skill 3 - Defining the System (Chapters of the requirements text ) Sriram Mohan 1

Outline Use Cases Organizing Requirements Vision Document Product Management 2

Use Cases 3

What is a Use Case? Sequences of actions Performed by system of interest Observable result of value to a particular actor 4

Benefits Easy to write and read Think from the perspective of an user Provides a clear idea of the “what” and the “how” User involvement 5

Use Case Model - Development Steps 1. Identify the actors 2. Identify the use cases 3. Identify actor/use case relationships 4. Outline use cases 5. Refine use cases 6

1. Identify the Actors Who uses the system? Who gets/provides information from/to system? Who supports the system? What other systems interact with this system? 7

2. Identify the Use Cases What are the intentions of each actor with respect to the system? Give a descriptive name: ◦ Start with an action verb ◦ Describes goal or intent Give a one-sentence description 8

3. Identify Actor/Use Case Relationships Draw a diagram showing relationships between actors and use cases 9 Eat foodBuy food Parent Child

4. Outline Use Cases Describe sequence of events in basic flow (sunny day scenario) Describe sequences of events in alternate flows (rainy day scenarios) 10

5. Refine Use Cases Describe sequences of events for flows Describe pre-conditions Describe post-conditions Fill in special requirements 11

Use Case Template A. Name B. Brief description C. Actors D. Basic flow E. Alternate flows F. Pre-conditions G. Post-conditions H. Special requirements 12

Microwave Example 13 User Cook Food

Cook Food Use Case – Slide 1 of 4 A. Name: Cook Food B. Brief description: User places food in microwave and cooks it for desired period of time at desired power level. C. Actors: User 14

Cook Food Use Case – Slide 2 of 4 D. Basic flow: 1.User opens door and places food in unit 2.User enters time for cooking 3.User pushes start button 4.Unit cooks food 5.Unit beeps 15

Cook Food Use Case – Slide 3 of 4 E. Alternate flows 1.User cancels time before starting 2.User cancels cooking before finished 3.User selects reduced power level before pushing start button 16

Cook Food Use Case – Slide 4 of 4 F. Pre-conditions ◦ Unit is plugged in ◦ Unit is in ready state G. Post-conditions ◦ Food is cooked or user cancelled operation H. Special requirements ◦ Timer should display remaining time to finish while cooking ◦ Default power setting should be "high" 17

18 Extending Use Cases Extend an existing use case instead of redefining it

19 Microwave Extension User Cook FoodSlice Food >

20 Including Use Cases Frequent sequences of events may be defined as use cases Including a use case is like calling a subroutine

21 Microwave Inclusion User Cook FoodSet Timer >

22 Cook Food Inclusion D. Basic flow: 1.User opens door and places food in unit 2.User performs Set Timer use case 3.User pushes start button 4.Unit cooks food 5.Unit beeps

Organizing Requirements – Why? Complex system Member of a product family 23

Organization Techniques Dividing requirements for complex systems into subsystems Product Families ◦ A series of products with closely related requirements ◦ Product lines – a new way of viewing software products  Investing in infrastructure to build product families  Develop systematic approach to building flexible application generators  Commonality analysis – used to determine if use of a product line will be beneficial 24

Economics of Families Current Practice 25 Number of Family Members Cumulative Cost Product Line Approach

Example Families Toyota automobiles and trucks IBM 360 computers Software? 26

The Vision Document 27

28 Let’s start with some vision… Do it first, Then the “lessons” might sound familiar… Get out a blank sheet of paper and something to write with. Put your name on it. In 1 minute, verbally sketch your beliefs about the “story” shown at right – 2 years from now – What did it become? Pass it to your left In 1 min, write your reaction to what you see written – Agree? Return it to the author …From your project description. “ This project would enable a user to share the real-time contents and actions of their computer screen with any remote user or group of users… ”

Purpose Comprehensive description of the product High level abstraction of the problem and the solution. Provides “common goals and a common playbook.” 29

Vision Document Template 1. Introduction 2. User Description 3. Product Overview 4. Feature Attributes 5. Product Features 6. Exemplary Use Cases 7. Other Product Requirements 8. Documentation Requirements 9. Glossary 30

31 How does it start? How does it end? Starts like the exercise you just did – ◦ Drawings and beliefs about the future Ends up like Figure 16-1, pp ◦ How this project fits into the development team’s plans ◦ Sample – See “Vision Doc Example” file, under Handouts  ◦ See Appendix A and E in the book

32 So, do we have to do one of these for our project? Problem statement Use cases Supplementary spec Paper prototype Usability Study Code-based prototype And now, for a taste of product management… These are the major artifacts your team will be responsible for delivering about the project  

Product Management 33

Rationale Every project needs an individual champion or a small champion team to advocate for the product. In a software products company, the product manager plays the role of the champion. The product manager drives the whole product solution: the application itself, support, user conveniences, documentation, and the relevant commercial factors. The Product Manager does high-level tasks – ◦ Listens to all the stakeholders ◦ Negotiates amongst them ◦ Manages and funds project people ◦ Communicates features and releases to the outside world ◦ Advocates the product to everyone ◦ “Owns” the vision statement! “to help software teams build products that customers want to buy” 34

Product Manager in the Hierarchy Chart 35

Driving the Product Vision 36

Maintaining the Road Map 37

A Product Manager’s Day Plan scenarios in which products provide answers 38 These pieces make the product manager’s vision!

Product Types from a Marketing POV There are two major variations: ◦ A “custom” product for a particular customer or small group of customers – They often act directly as “external clients” ◦ A “general” product for a target market – An executive or the product manager is the “internal client” for these future customers 39