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State purpose of use case diagram.

Purpose of Use Case Diagrams​

Use case diagrams are a fundamental modeling technique in the Unified Modeling Language (UML) that serve several important purposes in software engineering and systems development. These diagrams provide a graphical overview of the functionality provided by a system in terms of actors, their goals (represented as use cases), and any dependencies between those use cases.

1. Requirements Visualization​

  • Graphical Representation: Transforms textual requirements into visual models that are easier to understand
  • Big Picture View: Provides a high-level view of the system's functionality at a glance
  • Scope Definition: Clearly shows what is within and outside the system's boundaries

2. Stakeholder Communication​

  • Common Language: Creates a bridge between technical and non-technical stakeholders
  • Validation Tool: Allows business users to verify that their requirements have been correctly understood
  • Discussion Facilitator: Serves as a focal point for requirement discussions and reviews
  • Agreement Basis: Helps in reaching consensus about system functionality

3. User-Centered Focus​

  • User Perspective: Emphasizes what users want to accomplish with the system
  • Value Delivery: Focuses on how the system provides value to its users
  • Role Identification: Clarifies the different types of users and their interactions with the system
  • External View: Shows the system from an external perspective rather than internal workings

4. Functional Requirements Definition​

  • Functionality Capture: Documents the core functions the system must perform
  • Behavior Specification: Describes how the system responds to user requests
  • Feature Organization: Groups related functionality in a structured way
  • Completeness Check: Helps identify missing requirements or functionality

5. System Context Delineation​

  • Boundary Definition: Clearly establishes what is inside and outside the system
  • Actor Identification: Identifies all external entities that interact with the system
  • Interface Specification: Highlights the points of interaction between the system and external entities
  • System Scope: Helps prevent scope creep by defining the system's limits

6. Complexity Management​

  • Abstraction: Hides implementation details to focus on user goals
  • Modularity: Breaks down complex systems into manageable functional units
  • Relationship Modeling: Shows dependencies and connections between different functions
  • Hierarchical Organization: Allows for different levels of detail through relationships like include and extend

7. Test Case Development​

  • Test Scenario Basis: Provides a foundation for developing test cases
  • User Story Mapping: Helps in creating user stories for agile development
  • Acceptance Criteria: Informs acceptance testing requirements
  • Coverage Analysis: Ensures testing covers all user interactions

8. Development Planning and Organization​

  • Work Breakdown Structure: Helps divide the development effort into manageable pieces
  • Development Prioritization: Supports prioritizing implementation based on user needs
  • Incremental Delivery Planning: Facilitates planning for iterative development
  • Resource Allocation: Assists in assigning resources to different functional areas

9. Documentation​

  • System Documentation: Forms part of the official system documentation
  • User Manual Input: Provides structure for user manuals and help systems
  • Training Material Basis: Helps in organizing training materials around key functionality
  • Maintenance Reference: Serves as a reference during system maintenance and updates

By fulfilling these purposes, use case diagrams play a crucial role in ensuring that software systems are built to meet user needs, established within clear boundaries, and communicated effectively to all stakeholders involved in the development process.