18 terms

System Development Life Cycle

A systems analyst has been employed to update a computer system in a business.
The analyst needs to collect information about the requirements of the new system.
State three ways to collect information, giving an advantage and a disadvantage of each.
-allow departure from prepared/allows interviewee to elaborate on points / makes clients believe they are fully involved.
-time consuming/only gives the view of one person/biased views can be anonymous/cost effective.
-Allow a large number to have their say in a short time/allows all to feel involved .
-Very rigid structure/does not allow individual points/person filling it in may feel rail roaded/poor return.
Observation Of Current System:
-See system "warts and all"/see system with new eyes/see information workers may feel not important
-workers may not act naturally/may not see 'abnormal' procedures/business may be cyclical.
-Collection of documentation
-gives clear indication of inputs and outputs necessary/shows what workers and management find acceptable
-present documentation may not be effective / may be difficult to understand without more information.
Describe the waterfall model which can be used to document the system life cycle
-The results from one stage used to..
-inform the work on the next stage in the cycle...
-at any stage it may be found necessary to return to re-evaluate a previous stage.
State the purpose of a user manual
Gives instructions to software users allow them to successfully produce the desired results/explain error messages/that the user has done wrong.
State the purpose of a technical manual
Describes how the system works / useful for technician who may need to alter the system in the future.
A dairy company collects milk from farms and processes it before supplying dairy products to shops. It is taking over another business which will increase its size significantly. The decision is made to employ a systems analyst to produce a new computer system to help run the business
Explain why the problem must be defined accurately before the analyst starts work.
-The client does nor understand the potential of computer systems
-The analyst does not understand the dairy industry
-the two must pool their information in order to ensure the 'right' problem is solved
-the analyst may produce a solution which does not satisfy the client.
State why it is important to the client and to the analyst to evaluate the finished system
-Important to client because need to be sure it will perform as required / identifies areas where solution is lacking
-important to analyst because it determines the end of the job/the analyst being paid.
Identify three types of maintenance which will be necessary after the system is running, giving an example of why each is necessary.
corrective - to correct bugs found in software being used
adaptive - To alter software because of external need e.g. VAT paid on dairy products is changed to 10%
Perfective - To improve performance of software.
A systems analyst is employed to investigate the introduction of a new computer system to an organisation by carrying out a feasibility study.
Describe three factors which the analyst should consider about the proposed system.
-Technical Feasibility: Can hardware.software be found to implement the solution
-Economic Feasibility: is the proposed solution within budget / economic to run
-Social feasibility: Is the effect on the humans involved too extreme to be allowed / Environmentally sound?
-Skill level required / operational: is there enough skill in the workforce?
-What is the expected effect on the customer? If customer not impressed then there may not be a point
-Legal: Can the problem be solved within the law?
-Time: Is time scale acceptable?
The Analyst decides to use the spiral model of the systems life cycle.
Describe the spiral model.
-Analyst begins by collecting data followed by each of the other stages leading to...
-Evaluation, which will lead too..
-A return to data collection to modify the results
-important point is that the different stages are refined each time the spiral is worked through
-the above points, shown in diagrammatic form, are acceptable
Describe the function and purpose of a feasibility study.
-Technically feasible
-Economically Feasible
-is the workforce capable of running new system
-consideration of budget
-socially feasivle
-is the proposed system legal?
-is the proposed system possible?...
-in given time period
-purpose is to carry out initial enquiries...
-...to see if there are any reasons why new system may not be acceptable...
-...before starting to produce it
-plan may be revised if study highlights problems.
The analyst produces user and technical documentation for the new system.
State three items which would be contained in the user documentation.
-Input/output procedures
-using processing tools/how to operate the system
-backing up and archiving (procedures)
-File searching / maintenance of files
-error messages / trouble shooting
-Help available from...
-Required hardware specifications/system set up procedure
-Index / contents
Describe two kinds of diagram which may be in the technical documentation
-...Showing flow of data through system
-System Flow Chart
-...showing the operations involved/the algorithm
-...shows how data tables relate to each other.
Explain why a systems analyst needs to identify the information requirements of a system, and describe the different methods of fact finding that may be used.
points to include:
-need to ensure analyst undserstands the organisation requirements...
-or system produced may not meet requirements
-need to ensure correct hardware and software
-interview/one to one situation / can change course of questions/boss or client.
-questionnaire / many have their views considered / time saving/large workforce.
-observation/can see process in action / may not act as they would because being observed.
-meeting / can get views from many people at once/may be taken over by one or two people.
-document collection / indicates what data is actually collected.
State three items of content in each of:
The requirements specification of a system
-input requirements
-output requirements
-processing requirements
-clients agreement to requirements
The design specification of a system:
-Input design
-output design/choice of interface
-data structure(design)
-diagram of overall system
-processing necessary/algorithms/flowcharts
-system flow charts
-data flow diagrams
-UML diagrams
A systems analyst has been asked to produce a piece of software for a manager in an organisation.
Explain the importance of accurately defining the problem to be solved and state what each of the analyst and the manager are able to contribute to the problem definition
-The two people involved will have very different ideas of the problem/necessary that they solve problem which they agree on.
-...or manager will be unhappy/software will be useless...
-...analyst will not be paid.
-Analyst is expert in used of computers
-Manager is expert in area of problem
When the software has been completed, its installation will need to be planned. Describe two tasks which the analyst needs to plan as part of the installation strategy.
-Method of implementation/mention of one or more of: parallel / pilot.phased/direct
-training program must be devised/materials written.
-files must be created / need to produce files/adapt or reformat present ones.
-Hardware must be bought / installed / commissioned.
-system must be tested / with real data files/by users
-post monitoring for errors/provide technical documentation
Describe how prototyping can be used by the analyst as part of the design process.
-Simple version of the program to illustrate feature of the software
-normally used to illustrate input and output screens
-The screens are dummies in that they elicit no action
-used to show manager the way the system will look/allows issues to be spotted...
-...to allow manager to be part of the design process/to give feedback/evaluate
-used to research new ideas
-used to refine prototype
-may include a story board showing linking of screens.