The Systems Life Cycle: Development and testing

1. Does the system work as expected? The Systems Life Cycle: Development and testing

2. So far… • You have learnt about the stages involved in • Analysis • Design • So what comes next... • Creating the system • Testing the system • Improving the system

3. Testing • Each time that testing shows a problem there will need to be further... • Analysis • Development • Testing • This cycle can happen many times until the system is perfect

4. Creating data structures and program modules • Once designed by the systems analyst these must be created by the programmer • The programmer will follow the system analysts designs. E.g • Using the recommended programming language • Using the recommended software

5. Some businesses are able to use existing software to create their desired result • Access and Word for example could be used to mail letters to clients • Other businesses have to have a programme specially written for them this is know as: • Purpose built - OR - Bespoke

6. Testing strategies • The systems analyst will have created a test plan. • They will also have prepared a set of test data together with a list of expected results

7. Test data • Usually three types of data are tested • Normal – data which should be acceptable or valid in the system. • Extreme – only used when a range of data is used. Extremes of the range are tested. • Abnormal – Data which is not acceptable or valid in the system. • Lets look back at the data on the previous slide – which is which?

8. Copy the test plan table and try to come up with some more tests that you’d recommend a school tried on their new system.

9. Live data • Data which is already used by the business can be used to test the system. • The data output from the new and old systems should match. • If there are differences then there is a problem to be found and solved.

10. Improvements • After the test plan has been fully tested the systems analyst will have to check the results • Are there any problems which need to be solved? • Sometimes single stepping is used. This is when a system can be run just one step at a time until the problem is found

11. Introducing the system to the place it will be used The Systems Life Cycle: Implementation

12. Implementation • Once the system is ready there are 4 main ways of implementing it. • Parallel running • Direct changeover • Phased implementation • Pilot running

13. Direct changeover • Switch off the old system and switch on the new. • Simplest scenario • Old systems switched off, new system takes over completely • Non critical systems only • the new system replaces the old system in one go • saves money in wages/very fast method of implementation BUT • if anything goes wrong you don’t have the old system to fall back on • Cannot go back to old system if any problems

14. Parallel running • Both old and new systems run side by side till new system is working properly • Necessary in critical situations • If the new system breaks down you still have the old system as a backup BUT • It can be a slow process/all tasks have to be performed twice • Expensive in terms of resources (may need two sets of staff)

15. Phased implementation • New system is brought in one section at a time • Can ensure each part of new system works properly before changing the next part • Eg new library system BUT • Takes longer than direct changeover • If new system unsuccessful, may lose some data

16. Pilot running • Eg in large banks or corporations • One branch changes to new system, identifies any problems • Other branches function as normal • Problems can be identified & solved before new system is rolled out to all branches BUT • If new system unsuccessful, may lose some data

17. Summary • Direct changeover The old system is scrapped and immediately replaced by the new system. With this option there is a danger that there may still be problems with the new system. Even though it is the most risky type of changeover, many companies use this method. • Phased changeover The change over is split into phases or stages. Each stage is introduced one at a time and the old system is kept running to do the remainder of the tasks that have not yet been changed.

18. Summary (continued) • Parallel running Running both the old and new system until you are certain the new system is working correctly. Parallel running is likely to be the most expensive as it involves doing the work twice for a period of time. However, it is the safest. If there are any bugs in the new system, you can always go back to the old system while the problems are corrected. • Pilot changeover Changing over in a small part of the company to start with. Only when the system is deemed satisfactory will it be rolled out to the rest of the organisation. A supermarket introducing a new 'self-scanning' system might choose to introduce it in two or three stores at first. This is a pilot changeover.

19. The analyst can not stay with the business for ever – a guide to help the new users The Systems Life Cycle: Documentation

20. Documentation • Systems usually have two types of documentation • Technical documentation • User documentation

21. What information is in the documentation?