Chapter 1 – The Systems Cycle
Stages of Systems Life Cycle:
Systems Life Cycle – the stages that need to be completed to create a new or modified system. Referred to as a cycle as, after time, the process will be repeated.
Definition – the feasibility study is used to determine if it is feasible (practical, realistic, viable) to create the new system. It looks at how the current system could be improved and why a new system is required.
Investigation and Analysis – questionnaires, interviews, observations, meetings and document analysis can be completed during this stage. The results are analysed to get an understanding of the problem. The user requirements are defined and agreed with the client.
Design – objectives in investigation and analysis stage are followed. The methods and formats of data capture, input, output, structure of data, processing and validation routines, queries and reports are all designed. The project plan is also developed.
Implementation – this is taking the design and creating the system. A decision about software strategy, based on budget constraints set by client, is made. Coding, macros and queries are created with backup and data storage being considered.
Testing – it follows a test plan with the results being recorded and ensures the system is free of bugs/errors and meets the user requirements.
Installation – system is installed for the client. Installation strategy is chosen and the end user is trained to use the system.
Documentation – test plans, data and logs, user manuals, version and security details and program specifications are created and passed to the user
Evaluation and Maintenance – the basis on which the decision is taken to begin the life cycle again. It demonstrates the iterative nature of the life cycle. The solution should be evaluated once implemented. Maintenance is ensuring the system continues to meet the needs of the user.
Approaches to Investigating a System:
Questionnaires – adv : large numbers of people can be asked questions, cheaper than interviews, anonymous responses, dis: must be carefully designed, cannot guarantee 100% completion
Interviews – adv : a rapport can be developed with people who use the system, questions can be added and adjusted, dis: can be time consuming and costly, may not be able to interview everyone
Meetings – adv : a group of people can express different views, can gather or give information, body language can be seen, dis: the discussion can lose focus, some staff may not attend because jobs need to be done
Document Analysis – adv : can get factual information, dis: cannot be used when input, output and information are not document-based
Observations – adv : all aspects of work load, methods of working, delays, designs and ‘bottleknecks’ can be identified, dis: can be time consuming and costly, problems may not occur in observation, users may put on a performance when being observed
Software Development Methodologies:
Definition – a software development methodology which focuses on the early delivery to end users of an incomplete, but working, system…