Software Lifecycle Activities Quiz

Software Engineering - Chapter 4: Requirements Elicitation

• Software Lifecycle: A model for software development, outlining a series of activities with dependencies, supporting the development process. Examples include analysis, design, implementation, and testing.
• Lifecycle Questions: Essential questions during software development include: what activities to select, dependencies between activities, and scheduling strategies.
• Typical Lifecycle Activities: A typical software lifecycle involves initial requirements elicitation, analysis, system design, detailed design, implementation, and testing.
• Use Case Model: A model used to express the structure of activities in the software lifecycle. It describes the interaction between actors and the application's domain objects.
• Motivation and Challenges: Software lifecycle management is complex, demanding proper communication of problems and requirements to ensure the appropriate software is created.

Types of Requirements

• Functional Requirements: Describe the system's actions, or interactions with the environment, independent of implementation. They focus on what the system does. For example: "An operator must be able to define a new game."

• Nonfunctional Requirements: Describe behavior characteristics unrelated to system actions. They focus on system quality attributes, like response time. For example: "The response time must be less than 1 second."

• Constraints: These requirements are imposed by the environment or the client. Often these relate to the software implementation. For example: "The implementation language must be Java".

• Quality Requirements: These cover aspects like reliability, usability, performance, and other features of the resulting application. For example: "Throughput" defines the rate at which tasks will be completed.

• Scenario Types: Different types of scenarios support different phases of the software lifecycle, including as-is situations, visionary futures, evaluation tests (e.g., user tests), or training scenarios.

Scenarios and Their Uses

• Scenario Definition: A scenario is a detailed description of how a user interacts with a system, from the user's perspective, including data and contextual elements like location, social interaction, and resource limitations.
• Uses: Scenarios can be developed, used during requirements elicitation for requirements elicitation to establish a system vision, during Client Acceptance Tests to refine scenarios and to verify the system’s functionality, and during System Deployment to aid training.
• More Definitions: "Scenario" is defined as a narrative that describes user actions and experiences during system interactions.
• Scenario-Based Design: An iterative approach that emphasizes scenario development to inform design choices.

Requirements Management

• Requirements Validation: A quality assurance step validating whether requirements are accurate, complete, and consistent to ensure they adequately reflect the user's needs.
• Validation Focus: Correctness: requirements reflect the client's view; Completeness: all usage scenarios are described; Consistency: no conflicting requirements exist.
• Validation Issues: Changing requirements during the elicitation process, inconsistencies that arise when changes are made or new requirements are understood, can result in inaccurate or incomplete models. Validation tools are useful to address these impediments.
• Requirements Management Tools: Software tools like DOORS, RequisitePro, and Unicase facilitate requirements management, providing centralized storage and collaborative access, to help ensure effective management for multi-user environments.

Requirements Elicitation Challenges

• Background Differences: Diverse backgrounds of participants necessitate careful collaboration methods to bridge the gap between user needs and system specifications.
• Domain Knowledge: Developers and users must understand the problem and solution domains.
• System Boundary Definition: Establishing system boundaries is critical.
• Clear Specifications: Ensuring the requirements are unambiguous is essential for future success.

Additional Important Points

• Motivation: The initial motivation and challenges for the software development can vary depending on the scope—for example, Greenfield Engineering, Re-Engineering, or Interface Engineering projects have different motivations and requirements elicitation criteria.
• Prioritization: Prioritization of requirements, e.g., high, medium, and low priority, helps focus development efforts and clarifies the process flow for development.
• Template for Analysis: There is a formal template used for documenting and delivering requirements analyses.