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

CSSE 371 Software Requirements and Specification Don Bagert, Rose-Hulman Institute of TechnologySeptember 20, 2005

Thanks to Mark Ardis and Steve Chenoweth for some of the slides included.

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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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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

Eat food

Buy foodParent 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 TemplateA. Name

B. Brief description

C. Actors

D. Basic flow

E. Alternate flows

F. Pre-conditions

G. Post-conditions

H. Special requirements

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Microwave Example

User

Cook Food

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Cook Food Use Case – Slide 1 of 4A. 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

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Cook Food Use Case – Slide 2 of 4D. 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

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Cook Food Use Case – Slide 3 of 4E. Alternate flows

1. User cancels time before starting

2. User cancels cooking before finished

3. User selects reduced power level before pushing start button

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Cook Food Use Case – Slide 4 of 4F. 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"

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Organizing Requirements

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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

Number of Family Members

Cumulative Cost Product Line

Approach

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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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Purpose Every software project will benefit from having a

Vision document. The Vision document describes the application in

general terms, including descriptions of the target market, the system users, and the application features.

The Vision document defines, at a high level of abstraction, both the problem and the solution.

It gives the development team “common goals and a common playbook.”

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Vision Document Template1. 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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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!

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Product Manager in the Hierarchy Chart

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Driving the Product Vision

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A Product Manager’s Day Plan scenarios in which products provide answers

These pieces make the product manager’s 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