SOFTWARE ENGINEERING - SOFTWARE LIFECYCLE MODELS These slides contain a few different software lifecycle models.

THE BASIC WATERFALL MODEL Requirement analysis Design Implementation Testing Maintenance

A MODIFIED WATERFALL MODEL Requirement analysis - V&V Design - V&V Implementation - V&V Testing - V&V V&V = Verification and Validation Maintenance - V&V

PROTOTYPING FOR REQUIREMENT ANALYSIS Requirement analysis - V&V Design - V&V Quick Design - V&V Implementation - V&V Quick Implementa-tion - V&V Testing - V&V V&V = Verification and Validation Maintenance - V&V

THE SPIRAL (ITERATIVE) MODEL Risk analysis Prototyping Planning A2 B2 B1 A1 A0 B0 D1 C1 C2 D2 D3 C3 Client evaluation and input Model simulation Operational prototype Verification for next level

ITERATIVE SOFTWARE DEVELOPMENT It is useful to divide the development so that the subsequent releases are based on the previous releases. The feedback from the previous releases shows if the development is producing the right thing.

EVOLUTIONARY SOFTWARE DEVELOPMENT In evolutionary software development different activities (design, implementation, testing, and even requirements specification) may all progress at the same time. In this type of a situation controlling the project can be very difficult. Evolutionary software development may take place because it is not really known what is needed or how it can be achieved. Evolutionary software development may also be a sign of lack of control over the development process.

THE MANAGEMENT VIEW Do a feasibility study to find out whether it is feasible to implement a new system. Build new system: requirement analysis, design, implementation, testing Installation Maintenance and audit