System Development Life Cycle

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2 Δεκ 2013 (πριν από 3 χρόνια και 6 μήνες)

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System Development Life Cycle

What is SDLC?

The formal process by which organizations


build systems is known as SDLC.


Also referred to as

Application Development Life Cycle or

Structured Development Life Cycle

TQM/RE

TQM
-
Total Quality Management


Set of business practices which improve



profit and productivity

RE
-

Reengineering/Process Innovation


Changing fundamental procedures


reexamining/repositioning corporate


Strategies.

TQM/RE Goals


Improve quality of all company activities


Reduce costs


Improve timelines


Other business goals

Why systems fail?


Lack of communication between people


Continuing the old system


Failure of parts of system not fitting


Lack of management Support


Technological Incompetence


Changes in technology in the middle


Lack of user involvement/training/support

(missing JAD
-
Joint Application Development)


Why systems fail?

(Not following steps of SDLC)


System does not meet users’ needs


Unnecessary/insufficient hardware is acquired


Software inadequately tested

Six Phases of SDLC

1.
P
reliminary Investigation

2.
Systems
A
nalysis

3.
Systems
D
esign

4.
Systems
D
evelopment/Acquision

5.
Systems
I
mplementation

6.
Systems
M
aintenance


Person in charge: Project Leader

System Analyst/Engineer


1. Preliminary Investigation
(feasibility study)

Determine the organization’s objective


Read internal/external documents


Interview users/executives

Nature and scope of problems

Propose alternative solutions


leave the system as is



modify the existing system


develop a new system

Describe costs/benefits of each solution

Submit a preliminary plan with recommendation



1. Preliminary Investigation

Benefits

Tangible Cost savings


Profitability/Productivity

Intangible


Employer satisfaction


BPR (Business Process reengineering)


independent of IT


Processes are identified for bottlenecks,


removed, then IT is applied.

2. System Analysis

Gather data


documents, interviews, questionnaires,


observations, sampling

Analyze data


CASE tools, DFDs, Data Dictionary,


System Flowcharts, Connectivity



Diagrams, Grid Charts, Decision Tables

Write a report


Written report

Approval from the Manager next phase

3. System Design

Preliminary Design


describes the functional capabilities


of the system


CASE tools, PM Software

Detailed Design


Output Requirements


Input Requirements


Storage Requirements


Processing/Network Requirements


System Backup


4. System Development

Substantial expenditures of money/time

Acquire software

Acquire hardware

Test the System


Unit Testing


Integrated testing


Workable system ready to be implemented

5. System Implementation

Objective:

To make system not just workable but successful

1. Software Conversion/Data conversion


4 Major strategies

Direct Implementation

Parallel Implementation

Phased Implementation

Pilot Implementation

2. Documentation

3. Training




4. System Maintenance

Never ending phase


Adjustments/improvements


system monitoring

Auditing
-

independent auditor’s review

Evaluation
-

outside system analyst


Once the system is old enough

SDLC is started all over again.