1. Soft. Eng. I, Spring 07Dr Driss Kettani1 CSC-3324: Chapter II The Software life cycle & Software engineering process models Reading: I. Sommerville, Edition 7, Chap. 4

2. Soft. Eng. I, Spring 07Dr Driss Kettani2 The software life cycle (All) The steps that are gone through in a software engineering process form the software life cycle… From the very beginning (client requirements) till the decommissioning of the software… The details (contents, activities, deliverables, etc. ) and the sequence of these steps depend on the software process model that is adopted...

3. Soft. Eng. I, Spring 07Dr Driss Kettani3 Generic software process models The waterfall model Separate and distinct phases of specifications and development Prototyping development Specification and development are interleaved Component-based development The system is assembled from existing components

4. Soft. Eng. I, Spring 07Dr Driss Kettani4 A typical waterfall model schema Coding / Programming Requirements Engineering System & Software Design Integration & System Testing Operation & Maintenance

5. Soft. Eng. I, Spring 07Dr Driss Kettani5 A typical Waterfall model phases Requirements engineering System and Software Design Programming & Unit testing Integration and system testing Operation and maintenance The drawback of the waterfall model is the difficulty of accommodating change after the process is underway

6. Soft. Eng. I, Spring 07Dr Driss Kettani6 Prototyping Model - Called sometimes (wrongly) Iterative/Evolutionary model -

7. Soft. Eng. I, Spring 07Dr Driss Kettani7 Prototyping Categorization Prototyping Models Throw away model

8. Soft. Eng. I, Spring 07Dr Driss Kettani8 Throw-away prototyping Objective is to understand the system requirements. Should start with poorly understood requirements

9. Soft. Eng. I, Spring 07Dr Driss Kettani9 Prototyping Categorization Prototyping Models Throw away model Evolutionary Models

10. Soft. Eng. I, Spring 07Dr Driss Kettani10 Evolutionary models The objective is to work with customers and to evolve, from an initial prototype based on an initial outline, to a final system, via several intermediate prototype versions… Two sub models:

11. Soft. Eng. I, Spring 07Dr Driss Kettani11 Prototyping Categorization Prototyping Models Throw away model Iterative Models Evolutionary Models

12. Soft. Eng. I, Spring 07Dr Driss Kettani12 Iterative model… A relatively poor requirements understanding...

13. Soft. Eng. I, Spring 07Dr Driss Kettani13 Prototyping Categorization Prototyping Models Throw away model Iterative ModelsIncremental Evolutionary Models

14. Soft. Eng. I, Spring 07Dr Driss Kettani14 Incremental Model… A relatively good understood requirements … Requires an initial architecture before developing increments...

15. Soft. Eng. I, Spring 07Dr Driss Kettani15 Reuse-oriented development Based on systematic reuse where systems are integrated from existing components or COTS (Commercial-off-the-shelf) systems Process stages Component analysis Requirements modification System design with reuse Development and integration This approach is becoming more important but still limited experience with it

16. Soft. Eng. I, Spring 07Dr Driss Kettani16 Reuse-oriented development

17. Soft. Eng. I, Spring 07Dr Driss Kettani17 Activity cost distribution for different the 3 models