1. Software Development Module Code: CST 240 Chapter 3: Requirement Analysis Al Khawarizmi International College, Abu Dhabi, U.A.E Lecturer:Karamath Ateeq

2. Chapter 3: Requirement Analysis2 Outline Requirements Engineering Functional/non-functional requirements Feasibility study Requirements elicitation and analysis Requirements validation Requirements management Al Khawarizmi International College, Abu Dhabi, U.A.E

3. Chapter 3: Requirement Analysis3 Al Khawarizmi International College, Abu Dhabi, U.A.E Requirements engineering The process of eliciting, analyzing, documenting, and validating the services required of a system and the constraints under which it will operate and be developed. Descriptions of these services and constraints are the requirements for the system.

4. Chapter 3: Requirement Analysis4 Al Khawarizmi International College, Abu Dhabi, U.A.E Requirements engineering Involves a variety of people in an organization, such as: System end users and their managers. Engineers who are developing or maintaining other related systems. Trade union representatives. Others in the organization who will be affected by the system. All of the above are called stakeholders.

5. Chapter 3: Requirement Analysis5 Requirements engineering is a difficult process because: Stakeholders make unrealistic demands. Requirements are expressed in stakeholders language Different requirements from different stakeholders Political factors Analysis Environment Al Khawarizmi International College, Abu Dhabi, U.A.E Requirements engineering

6. Chapter 3: Requirement Analysis6 Al Khawarizmi International College, Abu Dhabi, U.A.E Software System Requirement Software System Requirements can be classified as –Functional Requirement: Functional requirement are the services the system should provide and what the software should do. –Nonfunctional Requirement: Non-functional requirements arise through user needs, because of budget constraints, because of organizational policies, because of the need for interoperability with other software or hardware systems, or because of external factors such as safety regulations or privacy legislation.

7. Chapter 3: Requirement Analysis7 Al Khawarizmi International College, Abu Dhabi, U.A.E Types of Non-functional requirements Product requirements – specify product behavior. Organizational requirements – derived from policies / procedures in customer’s or developer’s organization (e.g., process constraints). External requirements – derived from factors external to the product and its development process (e.g., interoperability requirements, legislative requirements).

8. Chapter 3: Requirement Analysis8 Al Khawarizmi International College, Abu Dhabi, U.A.E Non-functional classifications

9. Chapter 3: Requirement Analysis9 Al Khawarizmi International College, Abu Dhabi, U.A.E Examples of non-functional requirements Product requirement: 4.C.8 It shall be possible for all necessary communication between the system and the user to be expressed in the standard Ada character set. Organisational requirement: 9.3.2 The system development process and deliverable documents shall conform to the process and deliverables defined in XYZCo-SP-STAN-95. External requirement: 7.6.5 The system shall not disclose any personal information about customers apart from their name and reference number to the operators of the system.

10. Chapter 3: Requirement Analysis10 Difference between functional and non functional requirements. Non-functional Requirement Functional Requirement Sl.No Defines system properties and constraints e.g. reliability, response time and storage requirements. Constraints are I/O device capability, system representations, etc. Defines all the services or functions required by the customer that must be provided by the system 1.

11. Chapter 3: Requirement Analysis11 It does not describe what the software will do, but how the software will do it. It describes what the software should do. 2. Related to improving the performance of the business.For example: checking the level of security. An operator should be allowed to view only my name and personal identification code. Related to business. For example: Calculation of order value by Sales Department or gross pay by the Payroll Department 3.

12. Chapter 3: Requirement Analysis12 Nonfunctional requirements are difficult to test Functional requirement are easy to test. 4 Related to the system as a whole Related to the individual system features 5 Failure to meet a non-functional requirement may make the whole system unusable. Failure to meet the individual functional requirement may degrade the system 6

13. Chapter 3: Requirement Analysis13 Al Khawarizmi International College, Abu Dhabi, U.A.E Requirements engineering processes The processes used for RE vary widely depending on the application domain, the people involved and the organization developing the requirements. However, there are a number of generic activities common to most processes: –Feasibility study –Requirements elicitation (collection) and analysis –Requirements validation

14. Chapter 3: Requirement Analysis14 Al Khawarizmi International College, Abu Dhabi, U.A.E Role of the feasibility study Identify alternatives Analyse costs and benefits Establish priorities Present alternatives

15. Chapter 3: Requirement Analysis15 Al Khawarizmi International College, Abu Dhabi, U.A.E Feasibility study Determines whether or not the proposed undertaking is worthwhile. Aims to answer three basic questions: –Would the system contribute to overall organizational objectives? –Could the system be engineered using current technology and within budget? –Could the system be integrated with other systems already in use?

16. Chapter 3: Requirement Analysis16 Al Khawarizmi International College, Abu Dhabi, U.A.E Types of feasibility 1.Operational Feasibility –Identify how complex is the problem and check if the given solution will solve the problem. –It involves the analysis of: Performance (throughput, reliability, response time, and process improvement). Control (security and protection against fraud). Efficiency : does the system make maximum use of available resources. Ease of use and ease of learning.

17. Chapter 3: Requirement Analysis17 Al Khawarizmi International College, Abu Dhabi, U.A.E Types of feasibility Operational Feasibility (continued) –Will the solution fulfils the users’ requirements? To what degree? –How will the solution change the users’ work environment? –How do users feel about such a solution?

18. Chapter 3: Requirement Analysis18 Al Khawarizmi International College, Abu Dhabi, U.A.E Types of feasibility 2.Technical Feasibility –Is the proposed technology or solution practical? State-of-the-art (High-tech) technology vs. mature (old) technology. –Do we currently possess the necessary technology? –Do we possess the necessary technical expertise?

19. Chapter 3: Requirement Analysis19 Al Khawarizmi International College, Abu Dhabi, U.A.E Types of feasibility 3.Schedule Feasibility –Given the current technology and technical expertise, are the project deadlines reasonable? –What happens if we don’t finish on time?

20. Chapter 3: Requirement Analysis20 4.Economic Feasibility –Is the proposed system cost-effective? –What is the return-on-investment (ROI)? [ROI measures the magnitude of the benefits relative to the costs ] –What is the break-even point? [Break-even point is the time from the first money spent until the development investment has been recovered. ] Types of feasibility Al Khawarizmi International College, Abu Dhabi, U.A.E

21. Chapter 3: Requirement Analysis21 Al Khawarizmi International College, Abu Dhabi, U.A.E The Requirement elicitation (collection) and analysis process

22. Chapter 3: Requirement Analysis22 1.Domain understanding: develop an understanding of the application domain. Involves working with stakeholders to learn about the application domain, the services needed and the system’s operational constraints 2.Requirements collection: the process of interacting with the stakeholders to discover requirements. 3.Classification: organize the unstructured collection of requirements into coherent clusters. Al Khawarizmi International College, Abu Dhabi, U.A.E The Requirement elicitation and analysis process

23. Chapter 3: Requirement Analysis23 Al Khawarizmi International College, Abu Dhabi, U.A.E 4.Conflict resolution: finding and resolving conflicted requirements. 5.Prioritization: interacting with the stakeholders to discover the most important requirements. 6.Requirements validation: requirements are checked to discover if they are complete, consistent, and in accordance with what the stakeholders want from the system. The Requirement elicitation and analysis process

24. Chapter 3: Requirement Analysis24 Al Khawarizmi International College, Abu Dhabi, U.A.E Requirements Discovery Requirement discovery is the formal process of collecting information about problems, requirements, and preferences. It is also called information gathering or fact finding. The different fact finding techniques include 1- Observation: 2- Interviewing: 3- Questionnaires: 4- Searching:. 5- Sampling:

25. Chapter 3: Requirement Analysis25 Observation is a fact-finding technique wherein the systems analyst either participates in or watches a person perform activities to learn about the system. Al Khawarizmi International College, Abu Dhabi, U.A.E Requirements Discovery- Observation

26. Chapter 3: Requirement Analysis26 Whom to interview A.Top level managers To confirm project team understanding of the business. To get commitment for the project. B.Middle level managers To obtain greater understanding of the problem. To define the requirements in general terms. C.Operational managers To get a full more detailed information of the problem. To obtain the critical points about the work procedures. Al Khawarizmi International College, Abu Dhabi, U.A.E Requirements Discovery - Interviews

27. Chapter 3: Requirement Analysis27 Al Khawarizmi International College, Abu Dhabi, U.A.E 1.Unstructured interviews Informal, the interviewer develops the theme of the interview according to the answers. It is in the format of questions and answers. Used when the analyst wants to get general information about the business. Requirements Discovery – Interview types

28. Chapter 3: Requirement Analysis28 Al Khawarizmi International College, Abu Dhabi, U.A.E 2.Structured interviews –Uses standardized predefined questions in either open response or dead response format. –Uses a set of prescribed answers. –Used when the analyst wants to get full details about the business. Requirements Discovery – Interview types

29. Chapter 3: Requirement Analysis29 Al Khawarizmi International College, Abu Dhabi, U.A.E Requirements Discovery – Questionnaires They are sets of predefined and standardized questions arranged on a form to obtain information about a particular subject. They are used for: –Evaluating specific features of a system. –Investigate different opinions, knowledge, or attitudes towards the system. –They are sent via: mail, fax, e-mail, or in-person. They should be made easy for the user to complete because: –If the user find the questions difficult, they might not complete the questionnaire, which will result in low rate of return. –Avoid ambiguity, because ambiguous questions generate unreliable answers.

30. Chapter 3: Requirement Analysis30 Al Khawarizmi International College, Abu Dhabi, U.A.E Requirements Discovery – Types of Questions Open Ended [Free Format] Close ended [Fixed Format ] Mixed Open ended (or free format) : There is no predefined answers –Example: What types of computers do you currently have installed? namemodelqty

31. Chapter 3: Requirement Analysis31 Close Ended [Fixed format ] –Example: Multiple choice: Which of the following cities would you like to live in? a)New York b)London c)Paris d)Rome Rating Do you feel this class is important? a) Strongly agree b) Agree c) No opinion d) disagree e) strongly disagree Requirements Discovery – Types of Questions Al Khawarizmi International College, Abu Dhabi, U.A.E

32. Chapter 3: Requirement Analysis32 Al Khawarizmi International College, Abu Dhabi, U.A.E Requirements Discovery – Types of Questions Mixed –Example: In what type of business is your organization? 1)Government4) Trading 2) Military5) Others ( please specify) 3) Industrial ____________________

33. Chapter 3: Requirement Analysis33 QuestionnaireInterview Address a large crowdInterviews are conducted only with selected persons. Hence addresses a small group of people. Limited probing and follow-up done after collection of original data. Probing and follow-up is easy Respondents can be unknownInterviewee is known to the interviewer Unclear questions may not be clarified which my result in misunderstanding and wrong answers. Unclear questions can be clarified by both the interviewer and the interviewee. The information may not be so rich. The information obtained will be rich. Al Khawarizmi International College, Abu Dhabi, U.A.E

34. Chapter 3: Requirement Analysis34 Al Khawarizmi International College, Abu Dhabi, U.A.E All available written material that describes the business should be considered. In addition the documents that provide information should be catalogued for future reference. Requirements Discovery - Searching

35. Chapter 3: Requirement Analysis35 There are 3 groups of documents: A.Business documents –Annual reports, business plans and forecasting, organization chart, hand books, and advertising booklets. B.Current system environment documents –System description, data administration guidelines, system architecture documents, system flowcharts, database specifications, IT organizational chart, user manual. Requirements Discovery - Searching Al Khawarizmi International College, Abu Dhabi, U.A.E

36. Chapter 3: Requirement Analysis36 C.Current technical environment documents –Hardware distribution list, capacity planning documents, system software list, network documents, performance statistics, hardware and software plans. Requirements Discovery - Searching Al Khawarizmi International College, Abu Dhabi, U.A.E

37. Chapter 3: Requirement Analysis37 Al Khawarizmi International College, Abu Dhabi, U.A.E Sampling is the process of collecting a representative sample of documents, forms, and records. Randomization is a sampling technique characterized as having no predetermined pattern or plan for selecting sample data. Stratification is a systematic sampling technique that attempts to reduce the variance of the estimates by spreading out the sampling—for example, choosing documents or records by formula—and by avoiding very high or low estimates. Requirements Discovery - Sampling

38. Chapter 3: Requirement Analysis38 Al Khawarizmi International College, Abu Dhabi, U.A.E Viewpoint-oriented analysis For every system there are a group of stakeholders and each group has different interest in the system, each interest is called a viewpoint. To illustrate viewpoints lets take the example of ATM stakeholders

39. Chapter 3: Requirement Analysis39 ATM stakeholders Bank customers Representatives of other banks Bank managers Counter staff Database administrators Security managers Marketing department Hardware and software maintenance engineers Banking regulators Al Khawarizmi International College, Abu Dhabi, U.A.E

40. Chapter 3: Requirement Analysis40 Al Khawarizmi International College, Abu Dhabi, U.A.E Viewpoint-oriented analysis Any viewpoint may be considered as: 1.A data source or sink In this case the analyst must identify what data is produced or consumed and what is the process of doing that. A cross-check is made to discover data being produced but not consumed or vice versa. Used by the CORE method.

41. Chapter 3: Requirement Analysis41 2.A representation framework In this case, each viewpoint is represented by a different data model. The data models are cross-checked to discover requirements that would be missed. Used by the VOSE method Viewpoint-oriented analysis Al Khawarizmi International College, Abu Dhabi, U.A.E

42. Chapter 3: Requirement Analysis42 Al Khawarizmi International College, Abu Dhabi, U.A.E Requirement Validation Requirements validation is an activity that checks the requirements definition document for accuracy, completeness, consistency, and conformance to standards. Concerned with whether or not the requirements define a system that the customer really wants. Requirements error costs are high, so validation is very important.

43. Chapter 3: Requirement Analysis43 Al Khawarizmi International College, Abu Dhabi, U.A.E Requirements checking Validity. Does the system provide the functions which best support the customer’s needs? Consistency. Are there any requirements conflicts? Completeness. Are all functions required by the customer included? Realism. Can the requirements be implemented given available budget and technology Verifiability. Can the system be tested to determine whether or not the requirements are met?

44. Chapter 3: Requirement Analysis44 Al Khawarizmi International College, Abu Dhabi, U.A.E Requirements validation techniques Requirements reviews / inspections – systematic manual analysis of the requirements. Prototyping – using an executable model of the system to check requirements. Test-case generation – developing tests for requirements to check testability. Automated consistency analysis – checking the consistency of a structured requirements description.

45. Chapter 3: Requirement Analysis45 Al Khawarizmi International College, Abu Dhabi, U.A.E Requirements management Requirements management is the process of managing changing requirements during the requirements engineering process and system development. New requirements emerge during the process as business needs change and a better understanding of the system is developed.

46. Chapter 3: Requirement Analysis46 Al Khawarizmi International College, Abu Dhabi, U.A.E Requirements management The priority of requirements from different viewpoints changes during the development process. The business and technical environment of the system changes during its development.

47. Chapter 3: Requirement Analysis47 Al Khawarizmi International College, Abu Dhabi, U.A.E Requirements change management