Use Case Diagram

• A type of diagram in Unified Modeling Language (UML)
• Used to represent how users (actors) interact with a system
• Focuses on what the system does rather than how it does it.

Purpose of Use Case Diagram

• Shows functional requirements of a system
• Helps understand user interactions
• Useful for communication between developers & clients
• Provides a high-level view of the system

Main Components

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• Actor
• Represents a user or external system
• Can be:
• Human (e.g., Student, Admin)
• System (e.g., Payment Gateway)
• Use Case
• Represents a function or action performed by the system
• Written as a verb phrase (Login/ Register/ Withdraw Cash)

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• System Boundary
• A box that defines the scope of the system
• Everything inside = system functions
• Everything outside = actors
• Relationships
• Association
• Line between actor and use case
• Shows interaction
• «include»
• One use case always includes another
• Used for common functionality
• Example: "Place Order" includes "Make Payment"
• «extend»
• Optional behavior (executed under certain conditions)
• Example: "Login" can extend to "Forgot Password"

Generalization

• Inheritance relationship
• One actor/use case is a special type of another
• Example: Admin → User

Key Characteristics

• Focuses on user perspective
• Does NOT show internal logic
• Simple and easy to understand
• Used in early stages of software design

Steps to Create a Use Case Diagram

1. Identify actors
2. Identify use cases
3. Define system boundary
4. Connect actors with use cases
5. Add relationships (include, extend, generalization)

University Admission System

• Allows different users to interact with the system to complete the admission process efficiently.
• The Applicant starts by creating an account and logging into the system. After logging in, the Applicant fills out the admission application form, uploads required documents, and submits the application.
• The system may include a payment process, where the Applicant pays the application fee as part of submitting the application.

University Admission System

• Admission Officer is responsible for reviewing submitted applications, verifying documents, and updating the application status (such as accepted, rejected, or pending).
• Officer may also generate merit lists based on applicant data.
• Admin manages overall system operations, including managing user accounts, maintaining admission criteria, and overseeing system data.
• defined functionalities.

University Admission System

• Some use cases include Register Account, Login, Fill Application Form, Upload Documents, Submit Application, Pay Application Fee, Review Application, Verify Documents, Update Admission Status, and Generate Merit List. Certain use cases have relationships, such as Submit Application including Upload Documents and Pay Application Fee, while Login may extend to Forgot Password if the user cannot access their account.

An Online Clothing Store System allows customers and administrators to interact with the system to browse, purchase, and manage clothing products efficiently. The main actors involved in this system are the Customer, Admin, and Payment Gateway. The Customer begins by creating an account and logging into the system. After logging in, the Customer can browse clothing items, search for specific products, view product details, and add items to the shopping cart. Once satisfied, the Customer proceeds to checkout, enters shipping details, and makes payment through the integrated Payment Gateway to complete the order.

The Admin is responsible for managing the store’s operations, including adding new products, updating product details, managing inventory, and processing customer orders. The Admin can also update order status (such as shipped or delivered) and manage customer accounts if needed. The Payment Gateway handles secure transaction processing during the payment stage.

Some use cases in this system include Register Account, Login, Browse Products, Search Products, View Product Details, Add to Cart, Checkout, Enter Shipping Information, Make Payment, Place Order, Manage Products, Update Inventory, Process Orders, and Update Order Status. Certain relationships exist between use cases, such as Checkout including Enter Shipping Information and Make Payment, while Login may extend to Forgot Password if the user is unable to access their account.

The system boundary contains all these use cases, indicating that they belong to the Online Clothing Store System, while the actors remain outside and interact with the system through these defined functionalities.