1. System Development REASONS for SDLC
Make sure that the computer system works well
Makes sure that the computer system is up to date
Make sure that the computer system does what needs to be done
Continual Improvement and development of computer system

2. SCENARIO
Businesses would PAY professional companies for the support, backing and advice for their IT Systems.
These could be NEW businesses starting out and in need of advice in setting up a BRAND NEW COMPUTER SYSTEM or Businesses with existing systems that need support or advice

3. THEY ARE responsible FOR OUR
In School we use a company called CYNNAL with our support and advice on our IT system.
THEY ARE responsible FOR OUR
SDLC

4. System Development
All organisations have various systems to deal with different parts of the company:- wages, stock, accounts etc
A SDLC are a sequence of activities used to look at systems used within organisations.
These are used if any developments, changes or improvements are required for the system.
There are specific ACTIVITIES performed to carry out a SDLC - SIX STEPS
Investigation
Analysis
Design
Implementation
Maintenance
Evaluation
This is CYCLIC - continual system of looking at the system

5. SIX STEPS used to Perform a System Development Life Cycle
1. Identify & Investigate
2. Analyse
3. Design
4. Implement
5. Maintenance
6. Evaluation

6. 1. INVESTIGATION [i] Existing Hardware and Software
Areas that will be looked at:-
[i] Existing Hardware and Software
What does the organisation have already - what can be used again and what will have to be replaced.
[ii] Definition of the scope of the present system
What will the new system have to do - types of outputs – forms, graphs etc. How will data be inputted - new system might require a barcode system.
[iii] Major data processing functions and processes
High level (contextual view) data flow - Diagram of how data is processed within the system
[iv] Identification of problems with the present system
The present system might not have facility for inputting data by barcode.
School might be thinking of using a new registration system using biometric fingerprint device - the existing system might not support this system.

7. 1. INVESTIGATION
Areas that will be looked at:-
[iv] Identification of problems with the present system
The present system might not have facility for inputting data by barcode.
School might be thinking of using a new registration system using biometric fingerprint device - the existing system might not support this system.
[v] Identify user requirements for the new system
There might be new areas to be developed - company might be thinking of e-commerce as a new area.
[vi] Analysis of costs and benefits of the new system.
What will it cost in terms of money - training staff, buying new equipment hardware & software.

8. Before the work can start the system must be INVESTIGATED
1. INVESTIGATION
Before the work can start the system must be INVESTIGATED
Information about the system must be collected, this can be done by:-

9. 1. INVESTIGATION Interviews
Talk with managers and staff on how the existing system works and what are the problems, what possible improvements could be made.
Observations
Look at how the workers interact with the system, what do they do? How do they use the system?
Looking at records or documents
Look at outputs, printed forms etc, Orders created, manuals, user documents, job descriptions.
Questionnaires
Hand out questionnaires to employees, must be carefully designed, poor questions - poor results - no good.

10. CREATING A FEASIBLITY REPORT
1. INVESTIGATION
CREATING A FEASIBLITY REPORT
After all the investigation is carried out a FEASIBILITY REPORT is produced to see if the new proposals or changes can be made. No point beginning major changes and finding out that the system is not possible to achieve or would cost too much.
A Feasibility Report should include:-
[i] User requirements - what is required for the employees using the system
[ii] Existing system - what are the existing hardware and software used – possible to use again or new hardware and software needed.
[iii] Processing issues - what needs to be done.
[iv] Problems - limitations and issues with existing system
[v] Costs - how much will this cost, equipment, staffing,

11. Tools and techniques used to analyse systems
2. ANALYSIS
This is the process of going ahead with the new system after the investigation work and feasibility report has been produced.
This is the stage where further investigation to the system is required and the existing system is analysed in detail -
Tools and techniques used to analyse systems
- The existing system can be analysed by using a DFD - Data Flow Diagram
and
- Entity Relationship models – how data is related in the system

12. The Analysis will look at the following areas:-
1. How Data flows and is used within the Company
2. What type of data needs to be stored and how it is arranged
3. Structure of data tables

13. These are the symbols used when creating a Data Flow Diagram
2. ANALYSIS
PROCESS
DATA STORE
DATA FLOW
SOURCE

14. Level 0 Context Diagram 2. ANALYSIS
This is an example of how data flows within a Burger Bar
CUSTOMER
KITCHEN
Receipt
Customer Order
Food Order
Food ordering system
Management Reports
RESTAURANT MANAGER
Level 0 Context Diagram

15. LEVEL 1 DIAGRAM 1.0 3.0 2.0 4.0 CUSTOMER KITCHEN
Customer Order
1.0
Receive and transform Customer Food Order
KITCHEN
Food Order
Receipt
Goods
Sold
Inventory
Data
3.0
Update Goods Sold file
2.0
Update Inventory file
Inventory Data
Goods Sold Data D2
Inventory File
Goods Sold File D1
4.0
Produce Management Reports
Daily Inventory Depletion Amounts
Daily Goods Sold Amount
LEVEL 1 DIAGRAM
RESTAURANT MANAGER
Management Reports

16. 2. ANALYSIS
ENTITY - An object of the real world, can be a person, product, customer, place
ATTRIBUTE - A single item of data which is a fact about an Entity
ENTITY
ATTRIBUTE
- Class
- D/O/B
- Subject
- Number
PUPIL

17. 2. ANALYSIS RELATIONSHIPS Relationship between entities in a system;
Can be:-
ONE to ONE
ONE to MANY
MANY to MANY
ENTITY 1
ENTITY 2
ENTITY 1
ENTITY 2
ENTITY 1
ENTITY 2

18. Simple diagram of how relationship works for Book ordering system
2. ANALYSIS
CUSTOMER
DELIVERY
ORDER
BOOK
Simple diagram of how relationship works for Book ordering system
ORDER
BOOK
This diagrams shows that it is possible to make many orders on many books
Many to Many

19. ATOMIC Attributes 2. ANALYSIS Mr John Jones
Data must be atomic within databases.
For example the above data contains TITLE, FIRST NAME & SURNAME
Difficult to create a search for all people with Jones Surname
The data must be broken down to THREE Atomic Attributes
TITLE
FIRST NAME
SURNAME

20. 2. ANALYSIS
DATA DICTIONARY TABLES
Data is broken down stating the following:-
Contents
Field names
Data types
Relationships
Text field length

21. 3. DESIGN
This activity involves working out what will be needed for the system to work:-
Design of Inputs and Outputs for the system - user interfaces, data capture, forms, reports, graphs, printouts.
Networks required - best topology for system, speed of data transmission, wireless needs.
Types of hardware and software required - computers or laptops, monitors, printers, input devices.
Personnel issues - staff training needed, organisation of staff.
Security issues - data being stored, must be kept secure.
Design work will include guidelines for all of the above and how the system will work

22. 4. IMPLEMENTATION
This is the stage where the system is actually built.
- Hardware will be bought and installed, computer programmers will be installing software and programmes
- Testing the system at all levels - security, with real data.
- Training of staff to use the system

23. DIRECT CHANGEOVER PARALLEL CHANGEOVER PHASED CHANGEOVER
4. IMPLEMENTATION
CHANGEOVER METHODS
In order to move to a new system different methods can be used to changeover from the old system to a new system. Choosing which method depends on the organisation.
Is there an existing system
New location or different locations
DIRECT CHANGEOVER
PARALLEL CHANGEOVER
PHASED CHANGEOVER
PILOT CONVERSION

24. 4. IMPLEMENTATION
DIRECT CHANGEOVER
Direct Changeover (e.g. done over a weekend) is fast and efficient but there is great disruption if the system turns out to be less than perfect. Company cannot carry on if the system doesn’t work.
Unless the employees are trained before hand they wouldn't be able to use the system effectively until they get used to it - need training

25. 4. IMPLEMENTATION PARALLEL CHANGEOVER
Parallel Conversion is where the old system continues to be used alongside the new system for a few weeks.  This means staff have double the work to do.  However, the great advantage is that results from the old system can be tested against results from the new system.
Employees can still use the old system until they get used to the new system.
Business is able to carry on.

26. 4. IMPLEMENTATION
PHASED CONVERSION
Parts of the system is done gradually. If there is a problem with the new set up, then the problem can be sorted out before moving on to the next phase.
Only suitable if there is an existing system

27. 4. IMPLEMENTATION
PILOT CONVERSION
Pilot Conversion is where part of the organisation pilots the new system and evaluates it.
Ideal for very large companies - areas can be piloted and evaluated before moving on with further changes.

28. 5. MAINTENANCE
Once the system has been set up, it needs to be maintained.
Train staff
Update software & hardware
Software bugs sorted out
System crashes sorted out

29. Types of maintenance that can be carried out:-
1. Perfective
Fine tuning of system, improving speed, adding extra features.
2. Adaptive
Adapt the system slightly to accommodate new requirements, company might require a new method of inputting data
3. Corrective
Faults in the system, software bugs, download patches to correct software problems

30. These could be fine tuned to perfect the system
5. MAINTENANCE
Types of maintenance that can be carried out:-
1. Perfective - examples
Security issues - New viruses etc.
Particular part of the software awkward to use - creating and formatting tables.
These could be fine tuned to perfect the system

31. Types of maintenance that can be carried out:-
2. Adaptive - examples
Adapt the system slightly to accommodate new requirements, company might require a new method of inputting data.
Change in business - new line in products, system must be adapted to cater for this.
New legislation – laws - Data Protection,
New printers - need new drivers to work the printers

32. Types of maintenance that can be carried out:-
3. Corrective
Faults in the system, software bugs, download patches to correct software problems.
Problems may become apparent when using the software in real life situations. - formulas don’t work out averages etc.

33. Technical Documentation
5. MAINTENANCE
USER DOCUMENTATION
User Documentation
User manual explaining to the employees how to input data, print reports, create searches, how to save, how to open software. Screenshots and examples are given.
Technical Documentation
These would be at a Programmer level, flowcharts of system specification of system, user interface design. Programming language, installation guide

34. 6. EVALUATION
This stage takes place a few weeks after the system has been built or set up. Evaluation will look at the following areas:-
See if system does what the initial requirements asked for.
How happy are the clients
Review cycle - constant checking to make sure that things are still ok

35. Tools used to gather evaluation information:-
Quantitative testing - performance and speed of system. How easy is the system to use - marks out of 10 by users. [Quantitative can be measured ]
Error logging - system can register every time part of the system fails. The analyst can look at these and determine what needs to be done to improve the system.
Questionnaires - Ask users and business questions on how satisfied they are with the system. Ease of use, dependability etc.

36. Upgrading of hardware & Software Correction of software bugs
POST IMPLEMENTATION COSTS
When the system has been completed businesses are aware that there will be ongoing costs with a system, they will have to plan ahead and budget for these.
Training of staff
Upgrading of hardware & Software
Correction of software bugs
Help desks and support staff
Modification of system

37. BUSINESS MIGHT BE DISSATISFIED WITH SYSTEM BECAUSE OF THE FOLLOWING:-
1. The full range of user requirements has not been met, so the system does not live up to user expectations.
2.Change in business needs means system cannot deal with new demands placed on it.
3. Failure to supply users with the information they require.
4. User interface causes many user problems with increased help-desk use.

38. BUSINESS MIGHT BE DISSATISFIED WITH SYSTEM BECAUSE OF THE FOLLOWING
5. Problems with the software or system crashing owing to lack of rigorous testing.
6.Network performance or speed of access to stored data becomes unacceptable as more users are added to the system.
7. Modifications to the system are needed regularly and the system needs replacement with a new one.
8.Too much time is spent updating to the new system.

39. BUSINESS MIGHT BE DISSATISFIED WITH SYSTEM BECAUSE OF THE FOLLOWING
9.The cost of user support is too high.
10. There are security breaches which were not envisaged when the system was first developed.
11.Speed – hard drive filling up – demands of software
12. Fashion – hardware satisfaction
13.Compatibility issues using newer versions of software