AS1: Approached to System Development Flashcards
What is the software crisis
This is when new systems were being rejected/failing
Why where new systems being rejected/failing
Software was not meeting the needs of the user
May be functional but very difficult to use
Software development was not keeping pace with hardware development
Projects going over budget
Projects were late or never delivered
What are the reason for new system software systems
In short new systems needed to solve the existing problems
1) The existing system no longer meets the user requirements… Requirements do change over time
2) Development/maintenance of old systems too difficult, expensive
3) Advances in technology: (Tablets, 4g) New hardware, new software, development methods
What internal factors make requirements change
Business can change their focus
New products
Acquire a new business
Up scaling or down scaling
What are the external factors that make requirements change
Changes to legislation
Competitory Actions
New technology
What does a System Analyst do
The analyst number one job is to understand the needs of the user.
What is a functional Requirement
Functional requirements (Quantitive) Is something that the system must actually do. E.g. Stock control, reduce stock level when item sold
What is a non-functional requirement
Non-Functional requirements (Qualitative)
Alternative criteria on which this system will be judged- completed a task in ‘x’ amount of seconds
What is an interview
A set of question is developed asking key points about the current system. These are asked of a selection of key users by the analyst. Interview may be structured or unstructured
What are the advantages and disadvantages of an interview
ADV Follow up questions can be asked Can see body language DisADV Time consuming Difficult to repeat Hawthorne effect Only set opinion of individuals
What is a questionnaire
A set of questions are developed asking key points about the current system. Users complete a set of predetermined questions, which may be open or closed
Completed by a wide selection of users
What are the advantages and disadvantages of a questionnaire
ADV
Low cost way of getting opinions from large groups.
Allows for anonymity (real opinion)
Users can complete at own convenience
Quick to fill in
Well-designed can be easily analysed
DisADV
Difficult to design good quality questionnaires
Cannot ask follow up questions if responses are not as expected
Return rates can be very low
Cannot observe body language
What is an observation technique
The system analyst shadows key users…. and records their everyday activities
What are the advantages and disadvantages of an observation technique
ADV
Analyst gets first hand experience of system to help understand requirements
See how tasks are performed and can spot inefficiencies and problems
Can ask questions about their experiences of the system
DisADV
People don’t like that being observed and may act differently (Hawthorne effect)
Observers may get in the way and annoy staff
What is a document analyst
Samples of orders, invoices, reports are examined to identify the inputs and outputs.
What are the advantages and disadvantages of a document analysis
ADV
Can clearly see data flows
Clear understanding of data requirements and types
DisADV
Some important into may not be visible
Cannot see how information may be used
Cannot see any inefficiencies in processing etc.
What’s the role of a DFD
DFDs shows the flow of data through system
Can show what data is stored
Shows what data we need as input, Information produced and where it goes.
What’s the purpose of design
It is to produce a system specification, so we know what system we actually have to create.
What will a design include
Data structures Tables Relationships Storyboards (for interface) Data processing: Queries, calculations etc. Inputs + output- reports, charts, etc.
What is a storyboard
Layouts for the forms/ pages/ screens within the application
What is a prototype
A first cut, non-functional model of the system
Evaluated by the users who provide feedback
Modify the prototype and repeat until happy with the model
What are the two types of prototyping and explain them
Throw-away prototyping is when the model if finished, the analyst has a clear list of user requirements.. The model is no longer necessary, only the requirements move to next stage
Evolutionary prototyping is when the model is complete, they see what the final product will look like and then add functionality.
Why is a test plan created
It is created and mapped to the user requirements….functional+ non functional requirements
We write tests that match what the system need to do (not what we may later program)
What phase is a test plan created.
Design phase
What are the three types of test data
Valid, Extreme and invalid
Explain Valid- test data
Acceptable data within a given range…. correct
Explain Extreme- test data
Data is valid but on the very limits of what is acceptable
Explain Invalid- test data
Not acceptable, outside of the range
An exam paper must be given a grade between 0-100%
Valid:50
Extreme: 0-100
Invalid: -1 or 110
What is the importance of testing
We test to ensure that the system meets all of the requirements. The system functions correctly and the system is usable
List the high quality testing indicators
Sustainability, Usability, Effectiveness
Explain Alpha testing
Its also referred to application testing. It is done in house, by the developer. It uses test data. It checks to see if system functions as it meant too
Explain Beta testing
The software is given to a select group of users, they use it for a period of time. Feedback is given on any issues or problems. All known bugs or errors are fixed
What is Acceptance testing
It is carried out by a select group of end users who uses real volumes of data. They carry out the normal day tasks. The feedback any issues or problems to developers intended to ensure that the system solves all end users problems
Define implementation and what it includes
Implementation is the installation/setup of a complete working information systems. It includes: Installing hardware Installing software Configuring hardware and software Include user training
Name the four change over methods
Parallel, Direct, Phased and pilot
Explain parallel change over method
We use the old and new system at same time. Do this until were sure new system works correctly. Then drop old system.
ADV
Backup system: If new system fails we still have the old one operating
DisADV
Do every task twice, lots more work and overtime-expense
We use this on vital systems for finance and safety (air traffic systems)
Explain direct change over method
Stop using old system and the next start using the new. This happens over a weekend/holiday.
ADV
Start with the new system immediately .i.e. no duplication and additional costs
DisADV
No backup- (or no means of comparison)
Use this when new system is similar to old, .i.e. generic packages eg office, payroll where a failure will have limited impact
Explain phases change over method
New system is implemented bit by bit, it gradually replaces old system. When each bit is introduced, we use it for a while and ensure it is fully working and fully operational before introducing the next.
ADV
Slow implementation: Which helps user learn new system gradually.
Identifying problems: Only introducing small bits, any problems must exist there are easy to find
DisADV
No back up system
This will be used in large complex systems.
Explain Pilot change over method
New system is used by a small group of users. Any problems/bugs identified are fixed. Then given out to rest of users
ADV
Issues confined to smaller group
Both systems running for comparison of data
Pilot users can assist in training of other users
Most bugs and issues fixed before main implementation
DisADV
Not all bugs/problems will occur with smaller scale use, more use will occur and new bugs formed
This is used when an organisation has multiple locations doing same tasks.
What is a technical documentation and what’s it use
It is created in every large phase of development
For anyone designing, building and maintaining the system e.g. analysts, technicians, programmers etc.
It describes how the system works ….eg analysis report, design spec and test plan
What is user documentation
For the end user of system (not for technical people)
Describes how to use it- the system…. no technical language
User guide, installation instructions.
What is the purpose of maintenance
To keep the system working and for it to remain fit for purpose
So it can meet any new requirements needed, remain efficient/useable
Some requirements may have been missed during development
What does data need to be converted
To get data from old system to new.
The data in old system may not be compatible with data structures in new system.
Examples of data conversion happening
Convert existing data into a format compatible with new system… changing file formats, jpeg to gif.
Additional processing to change format eg one set of database tables to another (data structures)
Data from non electrical systems eg paper systems needs to be inputted into new system
