System Development Life Cycle

The CycleWhen 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 TargetsLetter Major Term Description Example Not acceptable!

S SpecificMake 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 MeasurableIs 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 RelevantIs 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 BoxInput 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