Sdlc Flashcards
Reasons for sdlc?
- Make sure that the computer system works well
- Make sure that the computer system is up to date
- Make sure that the computer system does what needs to be done
- Continual improvement and development of computer system
What are the six steps used to perform a system development life cycle?
- Identify + investigate
- Analyse
- Design
- Implement
- Maintenance
- Evaluation
What areas will be looked at In the investigation stage?
- Existing hardware and software
- Definition of the scope of the present system.
- Major data processing functions and processes
- Identification of problems with the present system
- Identify user requirements for the new system
- Analysis of costs and benefits of the new system
How is information collected about the system before investigation starts?
- Interviews - talk with managers and staff- how existing system works + what are the problems, possible improvements?
- Observations - look at how workers interact with system, what do they do? How to they use it?
- Looking at records or documents - look at outputs e.g printed forms, orders created, manuals, user documents, job descriptions
- Questionnaires - hand out to employees, carefully designed
What should the feasibility report include?
After investigation
- User requirements
- Existing system - use again or new?
- Processing issues - what needs to be done
- problems - limitations and issues with existing system
- Costs - how much? Equipment? Staffing?
What is an entity? (Analysis)
An object of the real world, can be a person, product, customer, place
What is an attribute? (Analysis)
A single item of data which is a fact about an entity
What relationships In a system can there be?
One to one
One to many
Many to many
What is atomic attributes? (Analysis)
Broken down into three attributes
- Title
- First name
- Surname
Difficult to create a search for all people with JONES surname
Data dictionary tables
Data is broken down stating the following - Contents Field names Data types Relationships Text field length
What happens at the design stage?
- Design of inputs and outputs for the system - user interfaces, data capture, forms, reports, graphs, printouts
- Networks required - best topology for system, speed of data transmission, wireless needs
- Types of hardware and software required - computers or laptops, monitors, printers, input devices
- Personnel issues - staff training needed, organisation of staff
- Security issues - data being stored, must be kept secure
- Types of hardware and software required - computers or laptops, monitors, printers, input devices
- Personnel issues - staff training needed, organisation of staff
- Security issues - data being stored, must be kept secure
What happens at the maintenance stage?
- where the system is actually built
- hardware bought and installed
- computer programmers install software and programmes
- testing system at all levels - security, with real data
- training of staff to use system
What is direct changeover? (Maintenance stage)
- fast, efficient but great disruption if system turns out to be less than perfect
- company cannot carry on if the system doesn’t work
What is parallel conversion? (Implementation)
- old system continues to be used alongside the new system for a few weeks
- this means staff have double the work to do
- great advantage is that the results from the old system can be treated against results from the new system
- business is able to carry on
What’s phased conversion? (Implementation)
- parts of the system is done gradually
- if there is a problem with new set up then the problem can be sorted out before onto the next phase
- only suitable if there is an existing system
