Models of Software Development Life Cycle (SDLC)

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2 Δεκ 2013 (πριν από 3 χρόνια και 8 μήνες)

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Unit 20

1

Models of Software Development Life Cycle (SDLC)


The objective of this section is to introduce you the idea
of
software process



a coherent set of activities for
software production. When you have read this section
you will:


understand the concept of a software process and a software process
model;


understand a number of different software process models such as
waterfall
,
spiral

and
iterative

models.



Unit 20

2


An SDLC

model breaks down the development process
into
a sequence of
phases or stages.



The end of a phase is called a
milestone

of the project. The
outcome of the phase is delivered to the customer as a
milestone of the project.



Breaking down the development process makes it easier to
manage.



Each phase can be performed in various ways.

What is a SDLC Model?

Unit 20

3

In the earlier days, projects were developed w
ithout
proper
specification or any attempt in design

and were

just buil
t
, and
reworked as many times needed to satisfy the customer.

This is not possible for complex projects since


There is no control on quality assurance.


There is no risk analysis.


There is no estimation of time and cost of the project.


There is no proper plan.

Hence,


The project may lead to a huge financial loss for both the customer
as well as the developer.


The project may fail.


The project may not be delivered in time with the satisfaction of the
customer.

Why use SDLC

Model
?

Unit 20

4

1. Waterfall Model


In the waterfall model, software activities proceed
logically

through a sequence of steps. Each step bases its
work on the activities of the previous step. The design
phase logically follows the requirements phase, the
implementation phase follows the design phase, and so on.



Waterfall model is document driven. In principle, the
result of each phase is one or more documents which are
approved (“sign
-
off”). The next phase should not start
until the current phase is completed.

Unit 20

5

Workflow of
Waterfall Model

Requirement

Verify

Implementation
Testing

Planning
Verify

Retirement

Design
Verify

Integration
Testing

Deployment and Maintenance

Specification
Verify



Development

Maintenance

Changed Requirements
verify

Unit
20

6

Quiz

1.
The planning of the project is done by:

A.
The programmer

B.
The system analyst

C.
The system study team

D.
The project manager

2.
During the Specification mode, the requirements are properly
documented and the document is called _________.

3.
The waterfall model is

1.
Document
-
driven.

2.
Risk
-
driven

3.
Prototype
-
driven