Presentation on theme: "System Development REASONS for SDLC"— Presentation transcript:
1 System Development REASONS for SDLC Make sure that the computer system works wellMakes sure that the computer system is up to dateMake sure that the computer system does what needs to be doneContinual Improvement and development of computer system
2 SCENARIOBusinesses 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 OURSDLC
4 System DevelopmentAll organisations have various systems to deal with different parts of the company:- wages, stock, accounts etcA 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 STEPSInvestigationAnalysisDesignImplementationMaintenanceEvaluationThis is CYCLIC - continual system of looking at the system
5 SIX STEPS used to Perform a System Development Life Cycle 1. Identify & Investigate2. Analyse3. Design4. Implement5. Maintenance6. Evaluation
6 1. INVESTIGATION [i] Existing Hardware and Software Areas that will be looked at:-[i] Existing Hardware and SoftwareWhat 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 systemWhat 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 processesHigh level (contextual view) data flow - Diagram of how data is processed within the system[iv] Identification of problems with the present systemThe 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. INVESTIGATIONAreas that will be looked at:-[iv] Identification of problems with the present systemThe 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 systemThere 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. INVESTIGATIONBefore the work can start the system must be INVESTIGATEDInformation 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.ObservationsLook at how the workers interact with the system, what do they do? How do they use the system?Looking at records or documentsLook at outputs, printed forms etc, Orders created, manuals, user documents, job descriptions.QuestionnairesHand out questionnaires to employees, must be carefully designed, poor questions - poor results - no good.
10 CREATING A FEASIBLITY REPORT 1. INVESTIGATIONCREATING A FEASIBLITY REPORTAfter 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. ANALYSISThis 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 Diagramand- 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 Company2. What type of data needs to be stored and how it is arranged3. Structure of data tables
13 These are the symbols used when creating a Data Flow Diagram 2. ANALYSISPROCESSDATA STOREDATA FLOWSOURCE
14 Level 0 Context Diagram 2. ANALYSIS This is an example of how data flows within a Burger BarCUSTOMERKITCHENReceiptCustomer OrderFood OrderFood ordering systemManagement ReportsRESTAURANT MANAGERLevel 0 Context Diagram
15 LEVEL 1 DIAGRAM 1.0 3.0 2.0 4.0 CUSTOMER KITCHEN Customer Order1.0Receive and transform Customer Food OrderKITCHENFood OrderReceiptGoodsSoldInventoryData3.0Update Goods Sold file2.0Update Inventory fileInventory DataGoods Sold DataD2Inventory FileGoods Sold FileD14.0Produce Management ReportsDaily Inventory Depletion AmountsDaily Goods Sold AmountLEVEL 1 DIAGRAMRESTAURANT MANAGERManagement Reports
16 2. ANALYSISENTITY - An object of the real world, can be a person, product, customer, placeATTRIBUTE - A single item of data which is a fact about an EntityENTITYATTRIBUTE- Class- D/O/B- Subject- NumberPUPIL
17 2. ANALYSIS RELATIONSHIPS Relationship between entities in a system; Can be:-ONE to ONEONE to MANYMANY to MANYENTITY 1ENTITY 2ENTITY 1ENTITY 2ENTITY 1ENTITY 2
18 Simple diagram of how relationship works for Book ordering system 2. ANALYSISCUSTOMERDELIVERYORDERBOOKSimple diagram of how relationship works for Book ordering systemORDERBOOKThis diagrams shows that it is possible to make many orders on many booksMany 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 & SURNAMEDifficult to create a search for all people with Jones SurnameThe data must be broken down to THREE Atomic AttributesTITLEFIRST NAMESURNAME
20 2. ANALYSISDATA DICTIONARY TABLESData is broken down stating the following:-ContentsField namesData typesRelationshipsText field length
21 3. DESIGNThis 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. IMPLEMENTATIONThis 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. IMPLEMENTATIONCHANGEOVER METHODSIn 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 systemNew location or different locationsDIRECT CHANGEOVERPARALLEL CHANGEOVERPHASED CHANGEOVERPILOT CONVERSION
24 4. IMPLEMENTATIONDIRECT CHANGEOVERDirect 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. IMPLEMENTATIONPHASED CONVERSIONParts 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. IMPLEMENTATIONPILOT CONVERSIONPilot 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. MAINTENANCEOnce the system has been set up, it needs to be maintained.Train staffUpdate software & hardwareSoftware bugs sorted outSystem crashes sorted out
29 Types of maintenance that can be carried out:- 1. PerfectiveFine tuning of system, improving speed, adding extra features.2. AdaptiveAdapt the system slightly to accommodate new requirements, company might require a new method of inputting data3. CorrectiveFaults in the system, software bugs, download patches to correct software problems
30 These could be fine tuned to perfect the system 5. MAINTENANCETypes of maintenance that can be carried out:-1. Perfective - examplesSecurity 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 - examplesAdapt 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. CorrectiveFaults 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. MAINTENANCEUSER DOCUMENTATIONUser DocumentationUser 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 DocumentationThese would be at a Programmer level, flowcharts of system specification of system, user interface design. Programming language, installation guide
34 6. EVALUATIONThis 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 clientsReview 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 COSTSWhen 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 staffUpgrading of hardware & SoftwareCorrection of software bugsHelp desks and support staffModification 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 software12. Fashion – hardware satisfaction13.Compatibility issues using newer versions of software