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System Development 2

System Development 2. Lectures 4. SDC Phases. In the previous lecture we have seen that SDC has following phases Planning Analysis Design Implementation Operation, support and security Let’s discuss them one by one. SDC Phase 1 - Planning.

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System Development 2

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  1. System Development 2 Lectures 4

  2. SDC Phases • In the previous lecture we have seen that SDC has following phases • Planning • Analysis • Design • Implementation • Operation, support and security • Let’s discuss them one by one

  3. SDC Phase 1 - Planning • Success of any project depends on its planning • Following activities are part of planning phase • Review project request • Time Planning • Cost Planning • Resource Planning • Hardware, Software, Human Resource etc • Form project team

  4. SDC Phase 2 - Analysis • Analysis means • what is the problem? • What is needed • Conduct preliminary analysis • Carry out detailed analysis • Study current system • Determine user requirements • Recommend solution

  5. Process modelling approach Describes the processes that change inputs into outputs Some tools used in this approach include: Entity-relationship diagrams Data flow diagrams Object modelling approach Also called object-oriented approach (OO) Combines the data with the processes that act on that data into a single object Analysis may take two approaches

  6. What is Entity-Relationship Diagram?

  7. What is Data Flow Diagram? There are many different ways to draw a DFD; there is no set procedure.

  8. Object oriented view In a traditional system the information (data) is viewed as separate from the processes

  9. Object oriented view Contd.. With the OO approach, the data and the processes are combined to create an object 1

  10. Finishing phase two • The last part of the analysis phase is usually to produce a system proposal • Discuss each option • Recommend a solution, which may include a recommendation about software: • Buy packaged software • Write custom software • Write software in-house or outsource it • If the proposal is accepted, move to phase three

  11. 1 Planning 2 Analysis 3 Design 4 Implementation 5 Operation, support and security Phase threeDesign Two main activities • Acquire hardware and software • Develop all details of the new or modified system • The system analyst will often perform these simultaneously

  12. DesignAcquire hardware & software • Identify technical specifications • Ask for proposals from vendors • Test and evaluate proposals • Make a decision

  13. Detailed design • Will vary according to the project, often involves: • Database design • Input/output design • A quality review

  14. Phase FourImplementation • Construct/build the new system • Deliver the system to the users • Develop programs • Install and test the new system • Train users • Convert to the new system

  15. Develop programs • For writing custom software, or modifying packaged software • May happen in-house or using outside people • Follow the 6-step program development cycle • Analyse requirements • Design the solution • Validate the design • Implement the design • Test the design • Document the solution These are discussed in the programming lecture

  16. Program Development Cycle • The program development cycle is part of the system development cycle, i.e. Programs are also developed in phases PDC Analyse Design Validate Implement Test Document 1 Planning 2 Analysis SDC 5 Operation, support, security 3 Design 4 Implementation

  17. SDC & PDC

  18. Install and test • Test things individually and as part of the system • Use test data • Using both incorrect and correct data • Use "real users" to test; the designers may be blind to their own mistakes

  19. Train users • Train all users • May be classes, web based, or 1:1 • User manuals (online or paper) should be provided

  20. Convert to new system • There are four main methods of converting

  21. Conversion • Direct • All at once • High risk, but cheap • Parallel • Run old and new systems together • Expensive and time consuming, but safe • Phased • The new system is introduced piece by piece • Expensive, slow, safe • Pilot • Entire new system is tried out in one part of the organization • Controlled risk

  22. Phase FiveOperation, support, security • Perform maintenance • Monitor system performance • Assess system security • There is usually a system review, then the system is "signed off" and the systems analyst's job is finished.

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