Requirement Management.ppt
- 2. Learning Objectives By the end of the lecture you should be able to: Explain what is software requirement analysis Describe how to carry out requirement analysis Explain different mechanisms of documenting requirement analysis Decision Table Decision Tree Structured English Use Case Diagram Use Case Template 2
- 3. What Are the Real Problems? the customer has only a vague idea of what is required the developer is willing to proceed with the "vague idea" on the assumption that "we'll fill in the details as we go" the customer keeps changing requirements the developer is "ratcheted" by these changes, making errors in specifications and development and so it goes ...
- 4. Software Requirements Analysis identify the “customer” and work together to negotiate “product-level” requirements build an analysis model focus on data define function represent behavior prototype areas of uncertainty develop a specification that will guide design conduct formal technical reviews
- 5. What is a requirement It is about WHAT not HOW Nothing can be said obvious Requirements are the descriptions of the services provided by a system and its operational constraints It may range from a high level abstract statement to a detailed mathematical specification It may be as complex as a 500 pages of description It may serve as the basis for a bid for a contract or the basis for the contract itself
- 6. Requirements engineering? It is the process of discovering, analyzing, documenting and validating the requirements of the system Each software development process goes through the phase of requirements engineering Business Requirement Document will assist throughout the project lifecycle to keep the deliverable in line with the business and customer needs.
- 7. Key points The software requirements document is an agreed statement of the system requirements. It should be organized so that both system customers and software developers can use it. The requirements engineering process is an iterative process including requirements elicitation, specification and validation. Requirements elicitation and analysis is an iterative process that can be represented as a spiral of activities – requirements discovery, requirements classification and organization, requirements negotiation and requirements documentation.
- 8. A spiral view of the requirements engineering process
- 9. Requirements Elicitation and Analysis Sometimes called requirements elicitation or requirements discovery. Involves technical staff working with customers to find out about the application domain, the services that the system should provide and the system’s operational constraints. May involve end-users, managers, engineers involved in maintenance, domain experts, trade unions, etc. These are called stakeholders.
- 10. Problems in Requirements Analysis Stakeholders don’t know what they really want. Stakeholders express requirements in their own terms. Different stakeholders may have conflicting requirements. Organisational and political factors may influence the system requirements. The requirements change during the analysis process. New stakeholders may emerge and the business environment may change.
- 11. Requirements elicitation and analysis process 11 •Requirements discovery, •Requirements classification and organization, •Requirements prioritization and negotiation, •Requirements specification.
- 12. Process activities Requirements discovery Interacting with stakeholders to discover their requirements. Domain requirements are also discovered at this stage. Requirements classification and organisation Groups related requirements and organises them into coherent clusters. Prioritisation and negotiation Prioritising requirements and resolving requirements conflicts. Requirements specification Requirements are documented and input into the next round of the spiral.
- 13. Types of Requirements Functional requirements Services the system should provide What the system should do or not in reaction to particular situations Non-functional requirements Constraints on the services or functions offered by the system Examples: Timing constraints, constraints on the development process, standards etc
- 14. Writing system requirements Natural language (informal requirements) Criticized by academics But widely practiced: everybody can read them, finding a better notation is hard Structured natural language Forms/templates are used to bring some rigor to natural language presentations Graphical notations Using boxes, arrows… but they mean different things to different people Formal specification Based on logic, state machines… Hard to understand for many people
- 15. Requirements Gathering Facilitated Application Specification Techniques Software Engineering Group Customer Group
- 16. Techniques for gathering requirement Brainstorming Document Analysis/ Gap Analysis Focus Group Interface Analysis Interview Observation Prototyping Requirements Workshop JAD Session (Joint Application Development) Survey/ Questionnaire
- 17. FAST Guidelines participants must attend entire meeting all participants are equal preparation is as important as meeting all pre-meeting documents are to be viewed as “proposed” off-site meeting location is preferred set an agenda and maintain it don’t get mired in technical detail
- 18. Key skill requirement for information gathering Good Communication Skills People Skills Strong Analytical Ability Healthy Relationship Building Domain Knowledge Technical Proficiency Reading and Listening Skills
- 32. Practice Sum
- 33. Use-Cases A collection of scenarios that describe the thread of usage of a system Each scenario is described from the point-of-view of an “actor”—a person or device that interacts with the software in some way Each scenario answers the following questions: What are the main tasks of functions performed by the actor? What system information will the actor acquire, produce or change? Will the actor inform the system about environmental changes? What information does the actor require of the system? Does the actor wish to be informed about unexpected changes