1. Requirements Gathering
How do we find out what we are supposed
to be building?

2. Why good Specs are Essential:$
It is VERY expensive to fix problems late in the process. It is very cheap to rewrite or clarify a written spec.
What costs $1 to fix at ReqGathering
$5 in the design stage
$10 in the coding stage
$20 in the unit testing phase
$200 after delivery

3. Types of Requirements Functional Non-Functional Explicit Implied
ex - it must the sales manager when an inventory item is "low"
Non-Functional
ex - it must require less than one hour to run
Explicit
ex – required features
Implied
ex – software quality
Forgotten
ex – exists in current process
Unimagined

4. Questions What makes a particular requirement good or bad?
Why is requirements engineering difficult?

5. Requirements of Requirements
Clear
Measurable
Feasible
Necessary
Prioritized
Concise

6. Req Gathering Problems
Accommodating changing reqs
Being complete, without being constraining
Conflicting views
Ease of omitting obvious info
Identifying the experts and getting authority to talk to people
Incomplete understanding of the problem on the part of the user/customer
Sticking with “what” and not “how”
Determining what is critical
Avoiding mission creep

7. Requirements WILL Change

8. Requirements Engineering Tasks
Inception
Elicitation
Elaboration
Negotiation
Specification
Validation
Management
Software Engineering: A Practitioner’s Approach by Roger Pressman

9. Inception Project starts due to a business decision
Software Engineer Asks:
What is the basic problem
Who wants a solution
Nature of solution

10. Inception Project starts due to a business decision
Software Engineer Asks:
What is the basic problem
Who wants a solution
Nature of solution
First Questions:
Who is behind the request for work?
Who will use the solution?
What will be the economic benefit of success?
Is there another source for the solution?

11. Elicitation Methods Interviews Use Cases
Formal Requirement Engineering Techniques

12. Elicitation via Interviews

13. Elicitation via Interviews
Difficulties:
Ill-defined project scope
Unnecessary details that confuse
Not sure what they need
Poor understanding of capabilities
Omitting the “obvious”
Requirements that conflict with other people’s requirements
Requirements Change!!!

14. Elicitation via Interviews
Recommended Practices:
The list of involved stakeholders must be broad!!!
Be sure to use real end-users.
Use agendas that cover the important points yet encourage flow of ideas
Ahead of time, the participants should build a partial list of the functions, performance criteria, environment factors, …
Start with scope and context, move to functions
Use visuals such as wall-stickers, flip-charts, …
Meetings with stakeholders should include the SwEngs

15. Elicitation via Use Cases
Diagrams composed of Actors and Actions
Logout
Anonymous
User
Registered
User
Create Account
Manage Account
Credit Card
System

16. Joint Application Design
Elicitation via JAD
Joint Application Design
JAD Sessions Participants:
Executive Sponsor
Project Leader
Facilitator – trained and experienced
Recorder
Participants
Observers – developers who sit on sideline and don’t talk
Outputs of sessions:
Data flow diagrams
Data requirements
List of assumptions
etc

17. Elicitation via QFD
Since 1966, Quality Function Deployment (QFD) has been used world wide in nearly every industry and sector to:
Prioritize spoken and unspoken customer wows, wants, and needs;
Translate these needs into actions and designs such as technical characteristics and specifications; and
Build and deliver a quality product or service by focusing various business functions toward achieving a common goal and customer satisfaction.
QFD uses interviews, surveys, and data (problem reports) to build a table of requirements called the Customer Voice Table.
Functional Deployment – value of each function
Information Deployment – identify the input and output
Task Deployment – examine system behavior
Value Analysis – prioritize the requirements

18. Elaboration Goal is to create a model that defines:
information
functions
What such a model looks like is the 2nd half of tonight

19. Negotiation Goal is to resolve requirements that are
Conflicting
Costly
Unrealistic
Identify the subsystem’s stakeholders
Determine their win conditions
Negotiate their win conditions into win-win conditions for everyone

20. Specification and Validation
Specification yields the SRS
Format of SRS is the 2nd half of tonight
Validation reviews the SRS

21. Review Requirements Engineering Tasks Inception Elicitation
Elaboration
Negotiation
Specification
Validation
Management