IT 3 System Development Life Cycle SDLC System

IT 3 System Development Life Cycle [SDLC] 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 SDLC

IT 3 System Development Life Cycle [SDLC] 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 SDLC

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

IT 3 System Development Life Cycle [SDLC] System Development All organisations have various systems to deal with different parts of the company: - wages, stock, accounts etc Investigation Analysis A SDLC are a sequence of activities used to look at systems used within organisations. Design These are used if any developments, changes or improvements are required for the system. Implementation There are specific ACTIVITIES performed to carry out a SDLC - SIX STEPS Maintenance This is CYCLIC - continual system of looking at the system Evaluation SDLC

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

IT 3 System Development Life Cycle [SDLC] 1. INVESTIGATION 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. SDLC

IT 3 System Development Life Cycle [SDLC] 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. SDLC

IT 3 System Development Life Cycle [SDLC] 1. INVESTIGATION Before the work can start the system must be INVESTIGATED Information about the system must be collected, this can be done by: - SDLC

IT 3 System Development Life Cycle [SDLC] 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. SDLC

IT 3 System Development Life Cycle [SDLC] 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, SDLC

IT 3 System Development Life Cycle [SDLC] 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 SDLC

IT 3 System Development Life Cycle [SDLC] 2. ANALYSIS 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 SDLC

IT 3 System Development Life Cycle [SDLC] These are the symbols used when creating a Data Flow Diagram 2. ANALYSIS PROCESS DATA STORE DATA FLOW SOURCE SDLC

IT 3 System Development Life Cycle [SDLC] 2. ANALYSIS This is an example of how data flows within a Burger Bar CUSTOMER KITCHEN 0 Customer Order Food ordering system Food Order Receipt Management Reports RESTAURANT MANAGER Level 0 Context Diagram SDLC

IT 3 System Development Life Cycle [SDLC] Customer Order CUSTOMER KITCHEN Receipt 3. 0 Receive and transform Customer Food Order Goods Inventory Sold Data 2. 0 Update Inventory file Update Goods Sold file Goods Sold Data D 1 1. 0 Goods Sold File Daily Goods Sold Amount LEVEL 1 DIAGRAM Inventory Data D 2 Inventory File 4. 0 Produce Management Reports Daily Inventory Depletion Amounts Management Reports SDLC RESTAURANT MANAGER

IT 3 System Development Life Cycle [SDLC] 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 PUPIL - D/O/B - Subject - Number SDLC

IT 3 System Development Life Cycle [SDLC] 2. ANALYSIS RELATIONSHIPS Relationship between entities in a system; Can be: ONE to MANY to MANY ENTITY 1 ENTITY 2 SDLC

IT 3 System Development Life Cycle [SDLC] 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 SDLC

IT 3 System Development Life Cycle [SDLC] 2. ANALYSIS Mr John Jones ATOMIC Attributes 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 1. TITLE 2. FIRST NAME 3. SURNAME SDLC

IT 3 System Development Life Cycle [SDLC] 2. ANALYSIS DATA DICTIONARY TABLES Data is broken down stating the following: - • Contents • Field names • Data types • Relationships • Text field length SDLC

IT 3 System Development Life Cycle [SDLC] 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 SDLC

IT 3 System Development Life Cycle [SDLC] 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 SDLC

IT 3 System Development Life Cycle [SDLC] 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 1. DIRECT CHANGEOVER 2. PARALLEL CHANGEOVER 3. PHASED CHANGEOVER 4. PILOT CONVERSION SDLC

IT 3 System Development Life Cycle [SDLC] 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 SDLC

IT 3 System Development Life Cycle [SDLC] 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. SDLC

IT 3 System Development Life Cycle [SDLC] 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 SDLC

IT 3 System Development Life Cycle [SDLC] 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. SDLC

IT 3 System Development Life Cycle [SDLC] 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 SDLC

IT 3 System Development Life Cycle [SDLC] 5. MAINTENANCE 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 SDLC

IT 3 System Development Life Cycle [SDLC] 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 SDLC

IT 3 System Development Life Cycle [SDLC] 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 SDLC

IT 3 System Development Life Cycle [SDLC] 5. MAINTENANCE 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. SDLC

IT 3 System Development Life Cycle [SDLC] 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 SDLC

IT 3 System Development Life Cycle [SDLC] 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 SDLC

IT 3 System Development Life Cycle [SDLC] 6. EVALUATION 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. SDLC

IT 3 System Development Life Cycle [SDLC] 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. 1. Training of staff 2. Upgrading of hardware & Software 3. Correction of software bugs 4. Help desks and support staff 5. Modification of system SDLC

IT 3 System Development Life Cycle [SDLC] 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. SDLC

IT 3 System Development Life Cycle [SDLC] 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. SDLC

IT 3 System Development Life Cycle [SDLC] 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 SDLC