Requirement Enginering Software Requirement Tutorial 9

7/29/2019 Requirement Enginering Software Requirement Tutorial 9

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Requirements Elicitation1

Lecture # 9


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Requirements Engineering Process

Requirements

Elicitation

Requirements

Analysis and

Negotiation

Requirements

Specification

Requirements

Validation

User Needs,

Domain Information,

Existing System

Information, Regulations,

Standards, Etc.

Requirements

Document

Agreed

Requirements


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Requirements Elicitation - 1

Elicit means to gather, acquire, extract,

and obtain, etc.

Requirements elicitation means

gathering requirements or discovering

requirements


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Requirements Elicitation - 2

Activities involved in discovering the

requirements for the system


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Basics of Knowledge Acquisition

Reading

Listening

Asking

Observing

These are the sources of knowledge

acquisition


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Requirements Elicitation

Techniques Individual

Group Modeling

Cognitive


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Problems in Requirements

Elicitation Problems of scope

Problems of understanding Problems of volatility


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Problems of Scope

The boundary of the system is ill-

defined

Unnecessary design information may

be given


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Problems of Understanding - 1

Users have incomplete understanding

of their needs

Users have poor understanding of

computer capabilities and limitations

Analysts have poor knowledge ofproblem domain


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Problems of Understanding - 2

User and analyst speak differentlanguages

Ease of omitting obviousinformation

Conflicting views of different users

Requirements are often vague anduntestable, e.g., user-friendly androbust


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Problems of Volatility

Requirements evolve over time and

hence there are some requirements

which are bound to change during the

system development process due to

one reason or the other.


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Contexts in Requirements

Elicitation Process

Organization

Environment

Project

Constraints imposed by people

Itis important to consider the context in

which requirements are being elicited.

Requirements elicitation process may be

followed in the following contexts


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Elicitation Process - 1 Organization

Submitters of input

Users of output

Ways in which the new system change

the business process


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Elicitation Process - 2 Environment

Hardware and software

Maturity of the target system domain

Certainty of the target systems interfaces

to the larger system

The target systems role in the larger

system


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Elicitation Process - 3 Project

The attributes of the different stakeholder

communities, such as the end users,sponsors, developers, and requirementsanalysts. Examples of such attributes are:

Management style

Management hierarchy

Domain experience

Computer experience


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Elicitation Process - 4 The constraints imposed by the people

They are involved in the elicitation

process, e.g., managerial constraints

concerning cost, time, and desired quality

in the target system


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Guidelines - 1 Assess the business and technical feasibility

for the proposed system

Identify the people who will help specifyrequirements and understand theirorganizational bias

Define the technical environment

Identify domain constraints that limit thefunctionality or performance of the system


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Guidelines - 2 Define one or more requirements elicitation

methods (interviews, focus groups, team

meetings) Solicit participation from many people so

that requirements are defined from different

points of view; be sure to identify therationale for each requirement that is

recorded


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Guidelines - 3 Identify ambiguous requirements as

candidates for prototyping

Create usage scenarios to help

customers/users better identify

requirements


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Ethnomethodology

Looks for behaviors that may be different in

a specific culture but which have the same

underlying purpose or meaning Conversational analysis

Measurement of body system functions

Non-verbal behavior studies

Detailed video analysis


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Requirements and Psychology

Errors in statements can happen in two

places

Perception of factsreality

Linguistic representation of one of these

perceptionspersonal reality

To remove these errors, requirementsshould be reviewed (during and after

elicitation)


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Use Case Modeling

Define actors and black-box use cases

The functional requirements of the

system are defined in terms of use

cases and actors

The use case descriptions are abehavioral view


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Summary - 1

Introduced the concept of elicitation andrequirements elicitation process

Basics of knowledge acquisition (reading,listening, asking, & observing)

Knowledge acquisition techniques(individual, group, modeling, cognitive)

Elicitation problems (scope,understandability, volatility)


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Summary - 2

Context (organization, environment,

project, constraints imposed by people)

Guidelines for knowledge acquisition


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References

Requirements Engineering: Processes

and Techniques by G. Kotonya and I.

Sommerville, John Wiley & Sons,

1998

Documents

Requirement Enginering Software Requirement Tutorial 9