Software Flashcards
What is the importance of defining the problem correctly?
A poorly defined problem can lead to a poor solution, unhappy customers who don’t my get what they want and will be unhappy with the developers who probably won’t get paid. Problems need to be understood so that the solutions will fix the problem. Misunderstanding can quickly develop between the dev and client
The systems life cycle describes the various stages that are gone through in analysing, designing and implementing a new computer system
Stages: Feasibility study Analysis Design Implementation Testing Installation Maintenance
Describe the function and purpose of a feasibility study?
A feasibility is don’t before any big work. The study will determine whether the problem under consideration is worth doing, and whether the solution is viable
What questions are asked during the study?
Is it: Technically feasible Economically feasible Is the workplace capable of running the new system Budget Socially feasible Legally feasible Is it possible in the time frame Any reasons if/why the new system may not be accepted
Methods of fact finding
Interviews
Questionaires
Observation of the current system
Collection of documents
Fact finding - interviews
Allow departure from prepared script/ allows interviewee to elaborate on points and make the client believe that they are fully involved. Time consuming - only give the view of one person
Fact finding - questionnaires
Allows for a large number to have their say in s short time - allies all to feel involved. Very rigid structure - doesn’t allow individual points - person filling it in May feel rail roared - poor return
Fact finding - observation of current system
See system warts and all - see system with new eyes - see information works may feel not important ; workers may not act naturally - may not see at abnormal procedures - business may be cyclical
Fact finding - collection of documents
Gives clear indication of inputs and outputs necessary - shows what workers and management find acceptable; present documents may not be effective - may be difficult to understand without more information
Explain why a systems analyst needs to identify the information. The information requirements of a system AND different methods of fact finding
Need to ensure analyst understands the organisation requirements or the system produced may not meet requirements
Need to ensure correct hardware and software
Interview - one to one situation can change course of questions
Questionnaire - may have their views considered can be time saving if there is a large workforce
Observation - can see process in action but employees may not act as they would usually
Meeting - can get views form many people at once but may be taken over by one or two people
Document collection - indicates what data is actually collected
State THREE items of content in the requirements specification of system
Input requirements Output requirements Processing requirements Clients agreement to requirements Hardware Software
Describe a design spec
After analysis. Explains in excruciating detail exactly how the new system is going to work. Will include mock ups of all input output forms, report structures, diagrams of overall system, algorithms, data dictionaries, data life diagrams, ERD and anything else that may be needed. It should be in enough detail so that any competent programmer could use it to create the new system
State THREE items of content in the design specification of a system
Input design Output design Data structure design Diagram of overall system Processing necessary - algorithms - flowcharts System flow charts Data flow charts Data flow diagrams Entity relationship diagrams Sitemaps
Importance of evaluating the new system
Any new system needs to be evaluated to ensure that it meets all of the design and requirement specification objectives, thus confirming as intended
Criteria that should be used in evaluation
Client must evaluate system to ensure that the requirements have been met
Analyst must evaluate the system to prove that they should be paid
Criteria should be agreed set of objectives of the system
This will be done by the rigorous testing of the system
Context and importance of different types of documentation at different stages in the system
Documentation on the new system will have been produced throughout the design process. Users will need their own documentation which will provide a complete account of how to use the new system. The maintenance programmers will need technical manual details all of the data structures and and technical features of the software.
State the purpose of each manual
User manual - Gives instructions to software users to allow then to successfully produce the desired result - how to fix errors and what the user has done wrong
Technical Manual - Describes how the system works
State 3 items which would be contained in user docs
Input output procedures how to use the system backing up File searching - maintenance error messages FAQ Help Hardware specs Glossary Index/contents
Describe 2 types of diagram which may be in the technical documentation
DFD - showing flow of data though out the system
System Flow Chart - showing how parts of system enterrelate
Flowchart - showing the operations involved, algorithms
ERD - shows how data tables relate to each other
Importance of system testing
A new system needs to extensively tested to ensure that all aspects of the system are working as planned. Test plans are created during the design stage and these will be followed to ensure that everything is working
System Installation - Direct Changeover
The old system is shut down and the new one is turned on. Usually done when there is no other option, as new systems don’t usually work first time.
System Installation - Parallel Changeover
The new system is installed alongside the old system. Both systems run together on the normal data. When the new system is clearly working the old system can be turned off.
System Installation - Pilot Changeover
If possible the new ystem is installed in one location where it will run, often for many months before it is rolled out in other locations. Alternatively, the new system is operated alongside the old system but with a subset of the data.
System Instllation - Phased Changeover
Some tasks previously performed by the old system are replaced with the new system. As confidence grows in the new system more and more tasks are undertaken by the new system until eventually the old system can be completely replaced.
