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Requirements Engineering Process-Softwarre Engineering-Lecture Slides, Slides of Software Engineering

This lecture was delivered by Umar Faiz at Pakistan Institute of Engineering and Applied Sciences, Islamabad (PIEAS) for Softwarre Engineering course. It includes: Requirements, Engineering, Process, Objectives, Topics, Covered, Feasibility, Requirements, Definition

Typology: Slides

2011/2012

Uploaded on 07/11/2012

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P

t II

P

art II

Requirements

Requirements Engineering Process

Software Engineering

Objectives

•^

To describe the principal requirements engineering

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hi

activities and their relationships

-^

To introduce techniques for requirements elicitationand analysis

-^

To describe requirements validation and the role ofrequirements reviews

-^

To discuss the role of requirements management in

q

g

support of other requirements engineeringprocessesp

Requirement Engineering

•^

Definition:– Establishing what the customer requires from a

software system.

  • A process in which “

what is to be done

” is elicited,

modeled and communicated. This process has todeal with different viewpoints, and it uses acombination of methods, tools and actors. Theproduct of this process is a model, from which adocument, usually a requirements definition isproduced [1].

[1] Leite, J.C.S.P, Freeman, P. A.

Requirements Validation Through Viewpoint

Resolution IEEE Transactions on Software Engineering: Vol

. 17, N. 1, pp: 1253 -- 1269,

g^

g^

,^

, pp

,

(1991). Extreme Requirements (XR) 13

docsity.com

Requirements Engineering Processes

•^

The processes used for requirement engineering

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d

di

vary widely depending on

Re

u q

re i

m

ne ts

eli

ci

ta

tio

n

Re

u q

re i

m

li^ ci

ta

tio

n

Application

domain

Problem to be

solved

Stakeholderneeds and

Businesscontext

needs andconstraints

context

Requirement Engineering

•^

Why Requirements Engineering important?– Serves as a standard against which verify and

validate.

  • Supports project management, e.g. resource

estimation (cost, personnel, skill, equipment, ..).

Requirements Engineering Processes

•^

The processes used for RE vary widely depending onth

li

ti

d

i^

th

l^

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l^

d

d th

the application domain, the people involved and theorganisation developing the requirements.

-^

There are a number of generic activities common toall processes– Requirements elicitation– Requirements analysis

q

y

  • Requirements validation

Requirements management

  • Requirements management

Requirements Engineering

1. Feasibility Studies

•^

A feasibility study decides whether or not the

d

t^

i^

th

hil

proposed system is worthwhile.

-^

A short focused study that checks– If the system contributes to organisational

objectives

  • If the system can be engineered using current

technology and within budget

gy

g

  • If the system can be integrated with other systems

that are usedthat are used

2. Elicitation and Analysis

•^

What is Elicitation?– Process of identifying needs– Involves social, communicative issues and

Technical issues

  • Involves technical staff working with customers to

g

find out about the application domain, the servicesthat the system should provide and the system’s

y

p

y

operational constraints.

  • May involve end-users managers engineers

May involve end-users, managers, engineersinvolved in maintenance, domain experts, tradeunions etc These are called stakeholdersunions, etc. These are called stakeholders.

2. Elicitation and Analysis

What

is

your

need

I need a system thatI^

need

a

system

that

works

OK

R b

t^

d

d

Robust

and

respond

to

my

wishes

Requirement Engineering Process

Requirements Elicitation Process

  • There are many possible requirements elicitation

processes and different organisations use differentprocesses.

  • A very general elicitation process model which

covers many of these different processes is givennext

Requirement Engineering Process

The Requirements Elicitation Process

Business

Establish objectives

Understand background

Organisational

Stakeholder Organise knowledge

Stakeholder Collect requirements

Business

goals

Organisational

structure

Stakeholderidentification

Goal

Stakeholderrequirements

Domain

Problem to be

solved

Application

domain

Goal prioritisation

Domain

Domain requirements

Systemconstraints

Existingsystems

Domainknowledgefiltering

Organisationalrequirements

2. Elicitation and Analysis

•^

Four critical activities– Knowledge organisation

  • The large amount of knowledge which has been

collected in the previous stage must be organised andcollated. S

k h ld

i^

ll

i

  • Stakeholder requirements collection
    • System stakeholders are consulted to discover their

i

requirements.

2. Elicitation and Analysis

•^

Specific elicitation techniques– Documentation– Interviews– Questionnaires– Scenarios

Scenarios

  • Ethnography