09 System Development Life Cycle (SDLC) Flashcards
Define the SDLC.
A SDLC is “a sequence of activities that are performed when a system is analysed designed and implemented”. This cycle is repeated as the software is updated and improved from time to time.
What are the stages of SDLC?
- Investigation
- Analysis
- Design
- Implementation
- Maintenance
- Evaluation
What four methods does a Systems Analyst use to gather information during the investigation phase?
- Questionnaires given to employees, managers or customers
- Interviews with managers and a few key employees and customers
- Observation of employees doing their normal day-to-day work
- Reading of documents and reports
What is adaptive maintenance?
Adaptive maintenance makes changes to the system to meet the changing needs of the business or organisation. I.e. as a company grows more employees might use the application than was expected. So the system may need more processing power to allow for this.
What is perfective maintenance?
Perfective maintenance improves the performance of the system after it has been implemented. For example, the database developer provides an upgrade that makes queries run faster.
What is corrective maintenance?
Corrective maintenance fixes bugs in the software that were not discovered during testing. For example, the software developer provides security patches that fix vulnerabilities.
How does a Systems Analyst use in-depth interviews during the investigation phase of the SDLC?
The analyst conducts interviews with managers, senior operations staff and the biggest customers and suppliers using both open and closed questions.
What is an advantage of using in-depth interviews during the investigation phase of the SDLC?
Interviews can reveal information the analyst had not considered. The analyst has the opportunity to ask follow-up questions and to request deeper explanation.
What is a disadvantage of using in-depth interviews during the investigation phases of the SDLC?
- Conducting interviews can be time consuming
* Results are qualitative, difficult to analyse and often cannot be represented in charts.
What is an advantage of using questionnaires during the investigation phase of the SDLC?
- Questionnaires are most effective when given to a large number of people, so that quantitative statistics can be produced
- Questionnaires are an efficient way of obtaining information from a large number of employees or customers, especially if they are in different locations.
What is a disadvantage of using questionnaires during the investigation phase of the SDLC?
• Questions are fixed in advance - respondents cannot respond to clarify. Staff may not return questionnaires or not fill them in accurately.
What four aspects should be considered in the design stage of the SDLC?
- House style
- Hardware specification
- Structures (i.e. database tables and fields)
- User interface
- Output reports
- Networks
- Staffing issues
- Security processes
A Systems Analyst has four choices of changeover strategy when a new IT system is introduced. Name them.
- Direct changeover
- Parallel changeover
- Phased changeover
- Pilot changeover
State an advantage and a disadvantage of direct changeover strategy.
- Advantage - Simplest and least costly
- Disadvantage - High risk. If new system doesn’t work perfectly the first time the company could face serious financial consequences.
State an advantage and a disadvantage of parallel changeover of IT systems.
- Advantage - Lower risk. If the new system doesn’t run properly, the old system is still running.
- Disadvantage - Cost of running two infrastructures may be high. Also, data must be entered and processed in two locations which is inefficient.
State an advantage and a disadvantage of phased changeover.
- Advantage - IT consultants are able to deal with a smaller number of issues as they arise
- Disadvantage - Only an option if the system can be broke down into modules.
State an advantage and a disadvantage of pilot changeover.
- Advantage - Lowers risk so if something goes wrong it only affects one location.
- Disadvantage - Takes the longest to implement and the system isn’t being tested at full scale.
Describe direct changeover of IT systems.
Direct changeover means the old system is switched off as the new system is powered up.
Describe parallel changeover of IT systems.
Parallel changeover means the new and old systems are run at the same time until the new system is ready to take over.
Describe phased changeover of IT systems.
Phased changeover means individual modules of the system are implemented one at a time
Describe pilot changeover of IT systems.
Pilot changeover means the system is tested in one or a few locations rather than in the whole company.
“A sequence of activities that are performed when a system is analysed, designed and implemented.” is the definition of what?
System Development Life Cycle (SDLC)
Analysis is which stage of the SDLC?
Second
Evaluation is which stage of the SDLC?
Sixth
