1. Mohammad Amin Kuhail M.Sc. (York, UK) University of Palestine Faculty of Engineering and Urban planning Software Engineering department Requirements Engineering Tuesday, 25 September 2007 Lecture 4 of RQE Processes

2. Introduction Other Requirement Process models and terminology used in literature. Processes of Requirements Engineering in the context of software development models. Managing the Requirements Engineering Processes and their deliverables Agenda

3. Other Requirement Process models and terminology used in literature Despite attempts to standardize requirements engineering, it is still not quite achieved. Why?

4. Other Requirement Process models and terminology used in literature Context analysis, Business analysis: attempts to establish the technical, economic, and operational boundary conditions for the software project.

5. Other Requirement Process models and terminology used in literature

10. Processes of Requirements Engineering in the context of software development models An abstract model (or conceptual model) is a theoretical construct that represents something, with a set of variables and a set of logical and quantitative relationships between them. a hypothetical description of a complex entity or process. Definition of model:

11. Processes of Requirements Engineering in the context of software development models Software Models:

12. Processes of Requirements Engineering in the context of software development models The waterfall model is a sequential software development model (a process for the creation of software) in which development is seen as flowing steadily downwards (like a waterfall) through the phases of requirements analysis, design, implementation, testing (validation), integration, and maintenance. Requirements Engineering in the waterfall model

13. Processes of Requirements Engineering in the context of software development models Requirements Engineering in the waterfall model

14. Processes of Requirements Engineering in the context of software development models Advantages Testing is inherent to every phase of the waterfall model It is an enforced disciplined approach It is documentation driven, that is, documentation is produced at every stage Advantages

15. Processes of Requirements Engineering in the context of software development models Criticism

16. Processes of Requirements Engineering in the context of software development models Requirements Engineering in the waterfall model

18. Processes of Requirements Engineering in the context of software development models Spiral Model steps: 1.The new system requirements are defined in as much detail as possible. This usually involves interviewing a number of users representing all the external or internal users and other aspects of the existing system. 2.A preliminary design is created for the new system. 3.A first prototype of the new system is constructed from the preliminary design. This is usually a scaled-down system, and represents an approximation of the characteristics of the final product. Requirements Engineering in the Spiral model

19. Processes of Requirements Engineering in the context of software development models Spiral Model steps: 4.A second prototype is evolved by a fourfold procedure: evaluating the first prototype in terms of its strengths, weaknesses, and risks; (2) defining the requirements of the second prototype; (3) planning and designing the second prototype; (4) constructing and testing the second prototype. 5.At the customer's option, the entire project can be aborted if the risk is deemed too great. Risk factors might involve development cost overruns, operating-cost miscalculation, or any other factor that could, in the customer's judgment, result in a less-than-satisfactory final product. Requirements Engineering in the Spiral model

20. Processes of Requirements Engineering in the context of software development models Spiral Model steps: 6.The preceding steps are iterated until the customer is satisfied that the refined prototype represents the final product desired. 7.The final system is constructed, based on the refined prototype. 8.The final system is thoroughly evaluated and tested. Routine maintenance is carried out on a continuing basis to prevent large- scale failures and to minimize downtime. Requirements Engineering in the Spiral model

21. Processes of Requirements Engineering in the context of software development models Spiral Advantages: –Risk reduction mechanisms are in place –Supports iteration and reflects real-world practices –Systematic approach Requirements Engineering in the Spiral model

22. Processes of Requirements Engineering in the context of software development models Spiral Disadvantages: –Requires expertise in risk evaluation and reduction –Complex, relatively difficult to follow strictly –Applicable only to large systems Requirements Engineering in the Spiral model

23. Processes of Requirements Engineering in the context of software development models Requirements Engineering in the Spiral model

24. Processes of Requirements Engineering in the context of software development models –Software prototyping is the process of creating an incomplete model of the future full-featured software program, which can be used to let the users have a first idea of the completed program or allow the clients to evaluate the program Requirements Engineering in the Prototyping model

25. Processes of Requirements Engineering in the context of software development models Requirements Engineering in the Prototyping model

26. Processes of Requirements Engineering in the context of software development models Advantages: –Reduced time and costs –Improved and increased user involvement Requirements Engineering in the Prototyping model

27. Processes of Requirements Engineering in the context of software development models Disadvantages: –Insufficient analysis –User confusion of prototype and finished system –Excessive development time of the prototype –Expense of implementing prototyping Requirements Engineering in the Prototyping model

28. Processes of Requirements Engineering in the context of software development models Requirements Engineering in the Prototyping model

29. Processes of Requirements Engineering in the context of software development models Requirements Engineering in the Domain Analysis model

30. Processes of Requirements Engineering in the context of software development models Requirements Engineering in the Domain Analysis model

31. Managing the Requirements Engineering Processes and their deliverables Rational behind specification items, Why?

32. Managing the Requirements Engineering Processes and their deliverables Rational behind specification items, Why?

33. Summary Why? –RQE is relatively young. –Varying degrees of formality treating RQE. –System analysis is ill-defined and ill-structured process. RQE Processes

34. Summary RQE Processes

35. Summary RQE Processes

36. Summary RQE Processes

37. Assignment Due Wednesday, 3 October 2007 Will be posted on the UPINAR tonight