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Write short notes on use case diagram with suitable diagram and their utility in system design.
Use case diagrams :
- Interaction with External Users:
- Use cases illustrate how a system interacts with external users or actors.
- Functionality Representation:
- Each use case represents a specific piece of functionality that the system offers to its users.
- Informal Requirements:
- Use cases are effective for capturing informal requirements, providing a high-level view of system functionality.
- Actor Inclusion:
- Use cases consist of actors, which are objects or sets of objects directly communicating with the system but not part of it.
- Quantization of Interactions:
- Interactions of actors with the system are quantized into use cases, simplifying the understanding of system functionality.
- Coherent Functionality:
- Use cases represent coherent pieces of functionality that the system can provide by interacting with actors.
- Example:
- For a vending machine, use cases include “Buy a beverage,” “Perform scheduled maintenance,” “Make repairs,” and “Load items.”
Utility of Use Case Diagrams in System Design:
- Functionality Identification:
- Use cases help identify the functionality of a system, organizing it based on user perspectives.
- Transaction Completeness:
- Use cases describe complete transactions, reducing the likelihood of omitting necessary steps in system operations.
- Focus on System Purpose:
- The main purpose of a system is often revealed through its use cases, with requirements lists providing additional implementation constraints.