System Development Life Cycle

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2 Δεκ 2013 (πριν από 3 χρόνια και 4 μήνες)

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System Development Life Cycle

The Cycle

When creating software, hardware, or any kind
of product you will go through several stages,
we define these stages in the System
Development Life Cycle.

Any System Development Life Cycle should
result in a high quality system that meets or
exceeds customer expectations, it should be
finished within time and cost limits, it should
work effectively and efficiently and is
inexpensive to maintain and cost
-
effective to
improve upon.

Analysis


In an analysis you have to find out the
problem and have a rough idea how to solve
the problem, this could be done by:


A detailed look at current systems


Establish the objectives of the new system


Use Smart Targets.




Smart Targets

Letter

Major Term

Description

Example

Not acceptable!

S

Specific

Make sure that it's not
ambiguous and it
concerns a part of
your system

The system should be
able to display 5 top
scores in descending
order

My system should be
good

M

Measurable

Is there any way that
you can easily prove
that you have met this
objective.

The game should load
in less than 5 seconds

My pages will be
beautiful

A

Attainable

Make sure that within
the time and resources
available you will be
able to complete the
objective

My system will allow
the saving of user
preferences

The system needs to
be complete and ready
to ship within 4 days

R

Relevant

Is the objective going
to help you meet your
user needs?

A receipt will be
printed and emailed to
the customer

My cashier system will
play MP3s in the
background

T

Time
-
bound

You are limited in the
time you have to
complete this project.
You must list the
deadline in your
Analysis somewhere
and can you finish
each objective in
time?

The system will re
-
use
code from previous
products

The system will involve
a completely new
game engine and code

Design


Design is important as it allows you to start
thinking about how you will make things, and
hopefully avoid making mistakes later.



The Process involved in the design of a
product are looking at:


User interface


Processes


Data storage requirements


Implementation


Implementation doesn’t just involve creating
the program, it involves;


Programming the software / creation of hardware


Installation of hardware and software


Preparation of data files


Training of users


Writing the system documentation


Testing


Once we have created our solution we need to
test that the whole system functions
effectively. To do this we need to do is
compare the finished product next to the
objectives that we set out in the Analysis.


There are several ways of testing a system,
‘black box testing’, ‘White Box Testing’, ‘Dry
Run Testing’

Testing (Black Box)





Consider the box to contain the program
source code, you don't have access to it and
you don't have to be aware of how it works.
All you do is input data and test to see if the
output is as expected. The internal workings
are unknown, they are in a black box

Black Box

Input

Output

Testing (White Box)





In white box testing you understand the
coding structure that makes up the program.
All the tests that you perform will exercise the
different routes through the program,
checking to see that the correct results are
output.

Testing (Dry Run Testing)


A dry run is a mental run of a computer
program, where the computer programmer
examines the source code one step at a time
and determines what it will do when run.

Evaluation


The final thing you should do is evaluate how
it all went
.



The
main part of the evaluation is to reflect on
how successful the operational system is:


Review to confirm the new system meets the
original objectives


Identify any necessary modifications