SYSTEM ANALYSIS AND DESIGN

1. SYSTEM ANALYSIS AND DESIGN

2. System Analysis Section 8 (pgs 94-101)

3. Introduction • What is a system ? • A system is an organized set of related components. It consists of input, processes, files (storage) & output designed to fulfill some useful purpose. • Need for system analysis. • (improve or change) • What is system life cycle? • System life cycle is the set of steps which is necessary to go through in developing a new system.

4. Introduction • Who is the system analyst? • A person who applies the techniques and procedures of system analysis & design. He plays an important role in the application of computer projects. • What are the functions of a system analyst? • Co-ordinates & schedules tasks with the programmers, managers, users, suppliers etc. • Plans & designs the new system. (All activities from the beginning to the implementation)

5. Stages In System Development Life Cycle • Analysis • Design • Development and Testing • Implementation • Documentation • Evaluation

6. System Life cycle analysis Design Development and Testing Implementation documentation evaluation

7. Assessment • What is a system? • What is system life cycle? • Who is a system Analyst? • List down the stages of system life cycle

8. Analysis Analysis is all about looking at how a job is done at present and seeing if the job could be done better by upgrading or developing a new system. This Phase consists of two sub stages • Fact Finding/ Problem recognition • Feasibilty study • Description of the current system • Identification of the problem • Defining the objectives • Identifiying the customers requirements • Interpreting the customers requirements • Producing preliminary designs and some alternatives with their cost benefit analysis • Preparation of the feasibilty report and data flow diagram

9. Problem Recognition There are four main ways of studying the existing system. • Asking questions/Interview staff: Interview users of the current system about their work and find out what is wrong with the present system and and what changes are required. • Observe staff at work : Sitting with various people to observe how the job is done. • Questionnaires: Make people to fill in carefully designed questionnaires about working practices. This method is used to get information from people who are not always at site or from people who are very busy and difficult to pin them down for interviews. • Inspection: Inspect all documents such as forms, invoices and receipts which are used in the present system Analysis

10. Feasibility Study: • This study looks at chances of developing a system at a reasonable cost within the time constraint. The study includes . • Objectives of the system. • A preliminary design with its cost/benefit analysis • Some alternative designs and its cost/benefit analysis where the benefits always outweigh the cost. • At the end of this study a report is made which includes the above. • At this point the decision-makers in the organisation, such as the board of directors in a company, decides whether to go ahead. • After the decision is made a report is made which includes. • Problems of the existing system. • Objectives of the Proposed system. • A proposed course of action.

11. Assessment • List down the four ways of analysing a system • Explain the following methods • Give advantages and disadvantagesof the following methods

12. Design:Once the requirements are known, the system can be designed. For the system to work, any or all of the following might have to be designed:  Inputs: • Where data comes from and how the data comes and what form the data comes as ie, text, numbers, pictures, sound etc. is worked out. • Data capture forms are designed • How much data has to be entered and how often it is to be entered is determined and decided. • What devices are required for data entry is chosen • Design of Input Screens is done

13. Data Capture forms

15. Screen input forms

16. File Design: Decision on how many files and structure of each file is designed without duplication to ensure integrity and consistency of data. • Code design: Codes are designed carefully as code entry takes less time and space. • Data preparation: verification and validation is included in data preparartion. Verification makes sure that if a keyboard is used no typing mistakes are made. Various validation measures are used to trap errors eg. Length, Range, type check etc. • Output Formats: • What form of output eg. Invoice, Bill, Dispatch note, packing List etc. are designed. • Design of output screens. • Report designs. • Hardware Configuration: What hardware is needed e.g. how many computers, Peripheral devices and will it be networked? • Software Configuration: What software is needed whether to go for a tailor made one or to go for an off-the-shelf package. Once this is decided the Operating system and the network software is decided. • FlowDiagrams: Flow charts are designed to show how the system works

17. Assessment

18. Development and Testing This includes:   • writing programs • purchasing hardware and software • installing networks • testing the system using the test plan • training staff Before the system is introduced and implemented it has to be tested for any errors.

19. Testing Testing is usually done with Test data and Live data Normal Data. The system is tested with data that contains no errors to see if it gives the correct results. Abnormal Data. Known errors are now introduced to check if the errors are trapped by the validation measures. Extreme values. Extreme values are entered to check if the range check given in the validation program is working.

21. Assessment and Recap • List down the two strategies of testing • Explain why do we need to test the system • Explain the following with examples • Abnormal • Normal • Extreme

22. After having the user acceptance of the new system developed, the implementation phase begins. Implementation is the stage of a project during which theory is turned into practice.During this phase, all the programs of the system are loaded onto the user's computer. After loading the system, training of the users starts. Main topics of such type of training are: Implementation • How to execute the package • How to enter the data • How to process the data (processing details) • How to take out the reports

23. After the users are trained about the computerised system, manual working has to shift from manual to computerised working. The following four strategies are followed for running the system: : • Direct • Phased • Parallel running • Pilot

24. Direct implementation: The changeover is done in one operation, completely replacing the old system in one go.  This usually takes place on a set date, often after a break so there is time to get the hardware and software for new system installed without causing too much disruption.

25. Direct implementation: Advantages: • The most rapid of all the strategies, provided it works! • Less risk of confusion between old and new systems. Disadvantages: • Most stressful for the users - the old system has gone so no going back if they have difficulties. • Most difficult to train staff on as the new system was not in place to learn on before the change over. • Most stressful for the developers - all the data and files from the old system will have to be converted ready for use on the new one. • Most risky - if the new system does not work properly then there is nothing to fall back on.

26. Phased implementation: With this strategy, the new one is brought in stages (phases).  If each phase is successful then the next phase is started, eventually leading to the final phase when the new system fully replaces the old one.

27. Phased implementation: Advantages: • Very structured, each phase can be fully evaluated before moving onto the next one. • Lower risk, a well planned and controlled introduction of the new system. • Easy to train staff by letting them learn new skills on each phase as it is introduced. Disadvantages: • Slower than direct implementation. • Although each phase is easy to evaluate, you have to wait until all the phases are complete before you can evaluate the whole change over.

28. Parallel implementation: With this strategy, the old and the new system are both used alongside each other, both being able to operate independently. If all goes well, the new system gradually takes over.

29. Parallel implementation: Advantages: • If there are initial problems with the new system then the old one can still be used. • Both systems can easily be compared. • Easy to train staff by letting them learn new skills on the parallel system. • Easy to evaluate because the new and old systems are both running. Disadvantages: • Expensive - both systems are being run as fully operating versions so both are doing the same job.  This may mean duplication of staff and hardware. • Some risk - there is a greater chance of confusion or errors if the two different systems are being run side-by-side.

30. Pilot implementation: With this strategy, the new system replaces the old one in one operation but only on a small scale.  For example it might be tried out in one branch of the company or in one location.  If successful then the pilot is extended until it eventually replaces the old system completely

31. Pilot implementation: Advantages: • Easy to control, the pilot can be halted at any time. • Easy to evaluate because the new and old systems are both running. • Low risk, if a small-scale pilot fails then not too much has been lost. • Easy to train staff by letting them learn new skills on the pilot system. Disadvantages: • It can be slow to get a pilot to completely replace the old system. • A pilot may not show up problems that a full-scale implementation would. This is because a system can work fine as a small-scale pilot but has difficulties when it is scaled up to a full operating system with more realistic volumes of data to be processed for example.

32. Assessment • List down the four strategies of implementaion. • Explain the following • Direct • Parallel • Phased • Give advantages and disadvantages of the following • Direct • Parallel • Phased

33. Documentation: A system needs to be documented to explain the system to the users of the system, analyst and programmers

34. Documentation is of two types mainly • User documentaion And • Technical documentation

35. User Documentation: User documentation will be written to help staff become familiar with the new system. This is usually written in simple English.

36. User Documentation: It will include: • installation details and purpose of the system • limitations of the system • hardware and software requirements • how to use the system • input and output samples • screen shots and sample runs • error messages (troubleshooting) • faq’s

37. Technical documentation This explains the system to system analyst or programmers and so is written in technical language. This is very important if the system has to be checked later or introduced to some new analyst or programmer.

38. Technical documentation This includes: • purpose of the system • limitations of the system • program coding • program flowcharts • system flowcharts • hardware and software requirements • file structures • list of variables and • validation routines

39. Assessment • Explain the need for documentation • Explain the following and describe its purpose • Technical Documentaion • User documentation • List down five main elements of the following • Technical Documentaion • User documentation

40. Evaluation • Evaluation is the final stage of developing a new system after implementation and is done along with the users and is done periodically to check if the system is meeting its objectives.   • The system is evaluated for • Efficiency • Ease of use • Appropriateness of the solution • by compare the solution with the original task requirements, • It is evaluated to check if it can it be improved further and to see if it needs to be modified. It is really re-analysing - starting the same systems analysis process all over again.