Đang chuẩn bị liên kết để tải về tài liệu:
Software design and architecture (Lecture Notes) – Chapter 19

Lecture 19 – Software requirement specification. 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. | Lecture Notes Lecture 19 – SOFTWARE REQUIREMENT SPECIFICATION REQUIREMENT: 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. REQUIREMENT 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. LEVELS OF ABSTRACTION : • User requirements have a higher level of abstraction. They are usually the first attempt for the description of the requirements. They describe the services and constraints of the system and are represented in natural language or diagrams and thus readable by everybody. These requirements serve business objectives. • System requirements are at a lower level of abstraction than user requirements since they keep in perspective the implementation details. These define the services and constraints of the system in detail and are useful for the design and development. The system requirements are more precise and cover all cases. They have more structured presentation. TYPES OF REQUIREMENTS: • Functional requirements: These are the services the system should provide. They describe what the system should do or not in reaction to particular situations • Non-functional requirements: These are the constraints on the services or functions offered by the system. Examples: Timing constraints, constraints on the development process (CASE, language, development method ), standards etc • Domain requirements: Domain requirements are extracted from the application domain of the system. These may be functional or non-functional. Examples: Medicine, library, physics, chemistry. Requirements engineering is comprised of five important activities: Feasibility study: It is done at first to decide whether or not the project is worthwhile. It look at different perspectives such as market analysis, financial, schedule, technical, resource, legal Requirements elicitation and analysis: Gathering the requirements and performing analysis on them. Requirements documentation: Documenting the elicited and analyzed requirements. Requirements validation: Validate the requirements from the stakeholders. Requirements management: Managing the changes in requirements.