requirements management with use cases module 6: define the system requirements management with use...

Requirements Management with Use Cases

Module 6: Define the System

Requirements Management with Use Cases

Module 6: Define the System

Requirements Management with Use CasesCopyright © 1998-2001 Rational Software, all rights reserved 2

Objectives: Define the System

Explain the purpose of a Vision document List the components of a Vision document Write a draft of the Vision Write a product position statement

Identify stakeholders and users Identify stakeholder/user needs Document product features Identify constraints

Develop and describe a use-case model Write a step-by-step outline


Where Are We in the Requirements Discipline?


Define the System: Activities and Artifacts


Organizing Project Artifacts

Develop or adopt standard templates Record your standards in QA Plan Benefits of standardization:

Leverages the work of others Quicker start, avoid reinventing the wheel Make sure things don’t fall through the cracks Everyone knows where to look for information Documents appear familiar and not intimidating Documents are easier to read


Specifications: Focus on Vision

+ Features

SoftwareRequirements

StakeholderNeeds

Vision Document

User Documentation Specifications

Design Specifications

StakeholderRequests

StakeholderRequests

SupplementarySpecificationUse-Case Model


System-level document that describes the “Whats” and “Whys” of the product or application

Focus User needs Goals and objectives Target markets User environments and platforms Product features

VisionDocument

Vision Document


Roles of the Vision Document

Communicate between management, marketing, and the project team

Provide for initial customer feedback Foster general understanding of the product Establish scope and priority of high-level features Record future features and ideas

A document that gets “all parties working from the same book.”


Vision Document Components

1. Introduction2. Positioning3. Stakeholder and User Descriptions 4. Product Overview5. Product Features6. Constraints 7. Quality Ranges8. Precedence and Priority9. Other Product Requirements10.Documentation Requirements11.Appendix 1 - Feature Attributes

TP4: Vision Document Template

- agree on the problem, capture vocabulary

- problem statementidentify

stakeholders/actors

- brainstorm features

- define boundaries

- identify constraints

- develop RM plan


Product Position Statement

Communicates intent and importance

Moore ‘91

Hint: Use Problem (analysis) Statement as a starting point!

For (target customer)

Who (statement of the need or opportunity)

The (product name)

Is a (product category)

That (statement of key benefits - that is - compelling reason to buy)

Unlike (primary competitive alternative)

Ourproduct (statement of primary differentiation)


Product Features

An externally observable service by which the system directly fulfills a stakeholder need

Examples: The Defect Tracking System will provide

trending information to help the project manager assess project status.

The ATM must allow a customer to transfer funds between accounts.

The graphical user interface will provide context-sensitive help.


Exercise 6.1: Create a Vision Document

Develop a vision for the class project Write a product position statement List identified stakeholders List identified users Summarize key stakeholder/user needs List the features for the class project List project constraints


Specifications: Focus on Use-Case Model

User Documentation Specifications

Design Specifications

StakeholderRequests

SupplementarySpecificationUse-Case Model

+ Features

SoftwareRequirements

StakeholderNeeds

StakeholderRequests

Vision Document


Use-Case-Model Survey: Template Use-Case-Model Survey

Gives a complete functional overview of the model

Shows a system’s intended functions and environment

May serve as a contract between the customer and the developers

Is input to activities in analysis, design, and test

Use-Case-Model Survey

1. IntroductionPurpose of the system

2. Survey DescriptionOverview of the use-case model

3. Use-Case-Model Hierarchy

ActorsName and brief description of each actor and its relationships

Use CasesName and brief description of each use case and its relationships

4. Use-Case DiagramsA list of all actorsA list of all use cases


RU e-st

QuoteSystem

TradingCustomer

AnotherActor

Use Case 3

Get Quote

Another Use Case

AnotherActor

Use Cases Show User Needs


Exercise 6.2: Describe the Use-Case Model

Review actors (Ex. 4.1) Identify use cases Identify communicates-associations Create a use-case diagram


Sample Use Case Diagram: RU e-st System

News System

TradingCustomer

Market Trading System

RU e-st Support

Review Account

Execute Trade

Apply for Trading Account

DistributeNews

Manage Portfolio

Get Quote

Quote System

Clock

RUCS4: Use-Case Model Survey


The Top 10 Use-Case Pitfalls

1. The system boundary is undefined or inconstant.2. The use cases are written from the system's (not the actors')

point of view.3. The actor names are inconsistent.4. There are too many use cases.5. The actor-to-use case relationships resemble a spider's

web.6. The use-case specifications are too long.7. The use-case specifications are confusing.8. The use case doesn't correctly describe functional

entitlement.9. The customer doesn't understand the use cases.10. The use cases are never finished.

...

From Lilly, S., Use Case Pitfalls: Top 10 Problems from Real Projects Using Use Cases,

Proceedings of TOOLS USA '99, IEEE Computer Society, 1999.


Packages: Grouping the Use-Case ModelThe Use-Case Model

Use-Case Packages

Top-Level Package

Use CasesActors Use-Case Packages


Avoid Functional Decomposition

Symptoms Very small use cases Too many use cases Uses cases with no

result of value Names with low-level

operations • “Operation” + “object” • “Function” + “data” • Example: “Insert Card”

Difficulty understanding the overall model

Corrective Actions Search for larger

context“Why are you inserting card?”

Put yourself in user’s role“What does the user want to achieve?”

“Whose goal does this use case satisfy?”

“What value does this use case add?”

“What is the story behind this use case?”


Brief descriptionBasic Flow 1. First step 2. Second step 3. Third stepA1 Alternative flow 1A2 Alternative flow 2 A3 Alternative flow 3

Use case name

Use-Case Outline


Step-by-Step Outline: Get Quote

Basic Flow1. Customer logs on2. Customer selects ‘Get Quote’ function3. Customer selects stock trading symbol4. Get desired quote from Quote System5. Display quote6. Customer gets other quotes7. Customer logs off

Alternative FlowsA1. Unidentified Trading Customer A2. Quote System Unavailable A3. Quit

What other alternatives can you think of?


Brief descriptionBasic Flow 1. First step 2. Second step 3. Third stepA1 Alternative flow 1A2 Alternative flow 2 A3 Alternative flow 3

Use case name

Exercise 6.3: Write a Step-by-Step Outline

Create a brief description of the use case Create step-by-step outline of flow of events


Review: Define the System

1. What is the purpose of a Vision document? 2. What are the components of a Vision document?3. What is in the product position statement?4. What is a product feature? 5. Which properties of actors and use cases are

specified in the Use-Case-Model Survey?6. What are some symptoms of functional

decomposition? 7. What is included in a step-by-step outline?

requirements management with use cases module 6: define the system requirements management with use...

Documents

product requirements

use cases copyright

system requirements

rational software

document product features

use cases module

documentation requirements

requirements discipline