SYSTEM LIFE CYCLES

OBJECTIVES o Be able to describe the stages of development of a hardware/software system. o Know what the different stages of the development life cycle involve

SYSTEM LIFE CYCLE It’s a structured plan of steps in order to complete a project or plan. There are lot of different life cycles each with their own defined steps and rules. Fortunately you only need to know the basic outline as per the diagram to the left AnalysisDesignImplementationTestingEvaluation

ANALYSIS PHASE This stage normally starts when it has been identified that a change is needed from current systems, this can happen due to a few reasons:  Change in the organisation  Technical developments  Outdated practices Included in this stage will be: Interviews Questionnaires ObservationsExamining Documents

DESIGN PHASE  As the name suggest this is where the project is design  It’s also more than just aesthetics that are though about Hardware Software Required Inputs & Outputs User interface Test plans

IMPLEMENTATION PHASE This is the stage that most people want to get to as you start to see something.  Development of software  Installation of hardware  Installation of software  Preparation of the data files  Training of the users  Writing system documentation

TESTING PHASE Such a crucial stage of the process, without stringent testing you can find a project will just fall apart. It’s also important to remember that you are testing more than just software, as hardware might have been installed Testing can be done in a variety of different ways  Black box testing  White box testing  Dry Run testing

EVALUATION PHASE This is looking back at the start of the project and reflecting on how successful the project is:  Does the system meet its original system objectives and requirements  How effective is the new system in solving the original problem  Can users operate the new system with out making mistakes or working under stressful conditions

QUESTIONS  During which stage of the system development life cycle would a user be asked what part they play in the functioning of the system and what they think the problems are?  How could a system analyst find out what the customer who regularly shop at a builders’ merchant thought of the current billing system?  Information is stored in filling cabinets. During which stage of the systems development life cycle is this information typed into computer files for use by a new computerised system?  Why is system testing necessary when the programmers have tested their code as they developed it?  Why is it necessary to check that the completed system meets the original requirements?