Team Skill 3 - Defining the System (Chapters 14-17 of the requirements text)

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Team Skill 3 - Defining the System(Chapters
14-17 of the requirements text)

• Sriram Mohan

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Outline

• Use Cases
• Organizing Requirements
• Vision Document
• Product Management

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Use Cases
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What is a Use Case?

• Sequences of actions
• Performed by system of interest
• Observable result of value to a particular actor

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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

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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

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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?

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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

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3. Identify Actor/Use Case Relationships

• Draw a diagram showing relationships between
  actors and use cases

Parent
Child
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4. Outline Use Cases

• Describe sequence of events in basic flow (sunny
  day scenario)
• Describe sequences of events in alternate flows
  (rainy day scenarios)

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5. Refine Use Cases

• Describe sequences of events for flows
• Describe pre-conditions
• Describe post-conditions
• Fill in special requirements

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Use Case Template

1. Name
2. Brief description
3. Actors
4. Basic flow
5. Alternate flows
6. Pre-conditions
7. Post-conditions
8. Special requirements

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Microwave Example
Cook Food
User
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Cook Food Use Case Slide 1 of 4

1. Name Cook Food
2. Brief description User places food in microwave
   and cooks it for desired period of time at
   desired power level.
3. Actors User

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Cook Food Use Case Slide 2 of 4

• Basic flow
• User opens door and places food in unit
• User enters time for cooking
• User pushes start button
• Unit cooks food
• Unit beeps

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Cook Food Use Case Slide 3 of 4

• Alternate flows
• User cancels time before starting
• User cancels cooking before finished
• User selects reduced power level before pushing
  start button

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Cook Food Use Case Slide 4 of 4

• Pre-conditions
• Unit is plugged in
• Unit is in ready state
• Post-conditions
• Food is cooked or user cancelled operation
• Special requirements
• Timer should display remaining time to finish
  while cooking
• Default power setting should be "high"

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Extending Use Cases

• Extend an existing use case instead of redefining
  it

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Microwave Extension
ltltextendgtgt
User
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Including Use Cases

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

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Microwave Inclusion
ltltincludegtgt
User
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Cook Food Inclusion

• Basic flow
• User opens door and places food in unit
• User performs Set Timer use case
• User pushes start button
• Unit cooks food
• Unit beeps

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Organizing Requirements Why?

• Complex system
• Member of a product family

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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

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Economics of Families

• CurrentPractice

Cumulative
Product LineApproach
Cost
Number of Family Members
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Example Families

• Toyota automobiles and trucks
• IBM 360 computers
• Software?

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The Vision Document
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Lets start with some vision
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

• 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.
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Purpose

• Comprehensive description of the product
• High level abstraction of the problem and the
  solution.
• Provides common goals and a common playbook.

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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

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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. 175-6
• How this project fits into the development teams
  plans
• Sample See Vision Doc Example file, under
  Handouts ?
• See Appendix A and E in the book

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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

? ? ?
These are the major artifacts your team will be
responsible for delivering about the project
And now, for a taste of product management
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Product Management
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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

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Product Manager in the Hierarchy Chart
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Driving the Product Vision
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Maintaining the Road Map
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A Product Managers Day

• Plan scenarios in which products provide answers

These pieces make the product managers vision!
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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