1.1 approaches to system development Flashcards
What is a system
A system is a set of processes
It systems use computer technology to complete a task
What is systems development
It is the methodology that is used when creating software
- software developers create new applications using code.
- they can pick different methods of software development- waterfall, rapid application development, agile.
Applications are developed either- from scratch, to replace paper based system- to replace and existing piece of software.
The software crisis
Term originated in the 1960s when computer hardware RAM CPU speed etc began growing much faster than the ability of software developers to actually make effective use of these new capabilities.
Cause of the software crisis
The machines have become several orders of magnitude more powerful!
- as long as there were no machines, programming was no problem at all. When we had a few weak computers, programming became a mild problem, and now we have gigantic computers, programming has become an equally gigantic problem.
What did the software crisis result in
Resulted in software that was low quality, did not meet users needs, was not delivered on time and was not within budget.
Updating old software also became a problem and this has continued ever since.
The need for software systems.
Individuals and organisations need SW to meet their needs. There are two ways to get SW.
off the shelf
Tailor made.
Off the shelf
Many buy same generic package. Ranges from productivity tools like MS office to specific SW for a common task. Eg. Payroll or accounting.
Sometimes these generic packages can be tweaked to suit each business eg. Use ur own templates in office.
Tailor made AKA bespoke.
Tailor Made
Your company uses a SW developer to create unique SW package just for ur specific needs.
Advantages of off the shelf
Meets general needs
Short developed time
Low cost
Disadvantages of off the shelf
Cannot meet all needs
Not developed enough
Tailor made advantages
Can meet all needs.
Do what needed to do.
Developed well
Factors affecting system development
- the requirements of the business may have changed.
- company expanded
- current system inflexible
- can’t get technical support- expensive
- advances in hardware and software
What does a computer system consist of?
User interface
Processes
Data
User interface
Allows the user to input data.
Shows the outputs after that data has been processed.
Processes
Raw facts and figures are processed to create useful information.
Data
User inputs- the desired temperature on an air conditioning or central heating unit.
- the time for an alarm to go off on a phone.
Senor inputs.
Large amounts of raw data from other systems.
- the examination results of every pupil in a school.
Systems Analyst
- analyse the data processing requirements of the organisation.
- produce a data processing requirements documentation that other member of the team will use.
- conduct feasibility study. a report which will determine whether or not user needs can be met.
- produce the systems specification. a detailed list of what the new system will contain. how it will be tested to make sure it meets set criteria. how the system will be implemented.
- deal with any problem that occur during the testing of the system.
Project manager
- to schedule the project
- split the project into specific tasks and sub tasks
- to allocate resources
- to identify and respond to risk or bottlenecks
- monitor the progress of the project
- to report back to clients as the project progresses.
Programmer
- responsible for writing the source code. Using a programming language such as Visual Basic. Written from the module specifications.
- develop a test plan and test the program.
Testing is usually not done by the programmer but instead by an independent software tester. - debug the program. Correct any faults found during testing.
- produce technical documentation. Notes about the code used l, how and why the programme was put together that way. Will be used during the maintenance stage.
