1. Use case diagrams show functional requirements without specifying order, data or control flow. Straight lines connect actors to use cases. 2. Actor generalization and use case extension/inclusion are shown. Extension improves on a use case, inclusion completes tasks for another use case. 3. External systems that use the system under design are represented, without data flow. Their placement is not critical.

1. Basics of Use Case Diagram
The very basics of Use case diagram

2. 1. No Concept of Flow in Use Case Diagram
• The use cases do not need to be
in ANY order
• Both  are same
And correct
• No data flow,
• No Control flow

3. Actor Generalization
• Actor 2 can login
• Can edit profile
• Can view reports

4. 3. Straight lines to use cases
• Without any arrows
• Without any crossovers

5. 4. Extends and Includes, (be wary of
directions)
• If a use case only completes
by performing multiple
tasks use includes
• If a use case improves upon
the features of another use
case then use extends.
• To complete “view reports” Authentication key must be provided. So “Provide
Authentication Key” is included in “View Reports”
• “Advanced Search” improves upon search therefore it “Extends” the “Search”

6. 5. What about the system actions
• One can argue that to View Reports,
the system should generate reports
• But as this is not a User function , So
we do not need to list it as a “Use
Case”

7. 6. What About External Systems
• Only external systems that “Use” features of Our system should be listed,
• Rules,
• Use a simple stick man as user for the external system
• Must NOT show any data flow
• Try to use the Lower right end of the Diagram to show external systems. (but is not
necessary)

8. That is All.
• Remember the purpose of Use case Diagram is to capture
functionalities ONLY.
• No Control or data flow (we use DFD’s or Business process models)
• No Sequential Activities, (we have activity diagram for that)
• No system responses.