System Development Life Cycle

lumpysteerΛογισμικό & κατασκευή λογ/κού

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

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Lecture 3

1

Introduction to

System Development Life Cycle
-

Part 2

Lecture 3

2

Objectives


Describe the objectives of Systems
Implementation phase in the SDLC


Describe the objectives of Systems
Operation and Support phase in the SDLC


Explain the use of software tools in the
development of information systems


Explain how different levels of a business
organization use and handle information

Lecture 3

3


Systems implementation


Construct/deliver information system


Prepares functioning, documented system


Write, test, document application programs


File conversion occurs


User and manager approval obtained




schedule for system installation and evaluation

Systems Development Life Cycle

Lecture 3

4



Users, managers, IS staff trained to operate and
support the system


Post
-
implementation evaluation performed


System operates properly?


Cost and benefits are within expectations?


Strengths and weakness of the new system



Systems Development Life Cycle

Click to see Figure

Lecture 3

5


Systems operation and support


New system supports business operations


Maintenance changes correct errors or meet
requirements


Enhancements increase system capability


After several years of operation, systems
experience need for extensive changes


Systems development life cycle ends with
system replacement

Systems Development Life Cycle

Lecture 3

6

Systems Development Life Cycle


General considerations


Complete the phases in sequence


Focus on end products / deliverables, they
represent milestones / checkpoints in the
system’s development


Estimate required resources

Click to see Figure

Lecture 3

7

Systems Development Life Cycle


Criticism


Real projects rarely follow the sequential flow,
iteration always occurs and creates problems


Difficult for the user to state all requirements
explicitly


The working system will not be available until
late



Lecture 3

8

Systems Development Life Cycle

Other development methods, e.g.


Prototyping


prototype
-

early version of the system,
built to serve as a model of user
requirements, discarded afterwards


the actual system is engineered based on
the prototype


focus on quality and maintainability
during development

Lecture 3

9

Systems Development Life Cycle


Spiral Model


SDLC + prototyping with risk analysis


1.Planning



2.Risk analysis



3.Engineering



4.Customer evaluation


Lecture 3

10

Systems Development Life Cycle


More complete versions of software are
built with each iteration


Lecture 3

11

Systems Development Life Cycle


Automated tools for systems development


Software tools
-

assist in the development
activities


Computer
-
aided software engineering
(CASE)
-

automates a specific systems life
cycle task

Lecture 3

12

Systems Development Life Cycle

Note :



Each phases of the SDLC will be
discussed in more details in later lectures



Lecture 3

13

TRADEOFF


Is it better to have more or fewer phases in
the SDLC?


More phases can result in more checkpoints,
end products, and work


Fewer phases can result in less cost and faster
development time


Success really depends on the skills and
motivation of the development team

Lecture 3

14

A KEY QUESTION


Should Momma’s, a small chain of 12 bed
and breakfast inns, adopt the SDLC process
of Global Hotels, a large multinational hotel
company?

Lecture 3

15

A KEY QUESTION
-
ANSWER


It depends on both companies’


corporate culture


IS policies


the organizational relationship



Clearly, there is quite a difference in
information needs between smaller and
larger firms



Lecture 3

16


Four organizational levels


Operational personnel


Lower management


Middle management


Top management

Organizational Levels

Click to see Figure

Lecture 3

17


Four organizational levels


Operational personnel


Lower management


Middle management


Top management


Responsibilities, decision
-
making styles, and
information system requirements

Organizational Levels

Click to see Figure

Lecture 3

18


Four organizational levels


Operational personnel


Lower management


Middle management


Top management


Responsibilities, decision
-
making styles, and
information system requirements


Empowerment of operational personnel

Organizational Levels

Click to see Figure

Lecture 3

19

End of Lecture 3