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Use Case Diagram

Use a case diagram is used to represent the dynamic behavior of the system

Use case Diagram contains following

  1. Actors
  2. The system
  3. The use cases
  4. Relationships


  • Actors: Actors are those who are interacting with the system, actors are two types primary and secondary actors. Primary actors are directly woks on the use cases and secondary actors have information about use cases, Actors are always outside the system Boundary
  • The system: The system itself has a system boundary and all actions are happening inside the system boundary.
  • The use cases: The use cases define the Process and the services which are contained in a system, use cases are considered as actions Which are interacting with the primary actor or secondary actors, the use cases are two types essential use cases and supporting use cases
  • Essential use case: essential use case contains main actions
  • Supporting use case: supporting use cases are supporting the essential use cases. These are considered as a sub of an essential use case
  • Relationships: Relationships in the use case diagrams are the connection between the actors and users. And the use case to use case


Use case Relationships


  1. Generalization
  2. Include
  3. Extend
  4. Association


Generalization: Generalization is used between use cases, we have to use Generalization when the essential use case contains the Supporting use cases, and those use cases are generalized.

EX: Customer can make payment using

  1. Cash
  2. Card
  3. Net Banking
  4. UPI

These types of situations payment are an essential use case and 4 Options are the supporting use cases, The customer can select any one of the options, we have used the Generalization this kind of situations.

Include:  Include is used between the essential use cases and supporting use cases, include is used when the supporting uses are mandatory to essential use cases.

Example: A customer wants to sign in he must enter the user’s name and password

These types of situations sign are the essential use case and the user’s name and password are the supporting use cases, they are must to complete the action.

Extend: Extend is used between essential use cases and supporting use cases, extend is used when the Supporting use cases are not mandatory.

Example:  A passenger want to Book a Flight ticket The following Options are Display

  1. Date/time
  2. Flight name
  3. 1 way/2 way
  4. Class
  5. Available/ not Available
  6. Food preference
  7. Seat preference

In these types of situations, food preference, and seat preference are not mandatory to book a ticket so in this kind of situation we have to use the extended relationship between essential use cases and supporting use cases.

Association: Association is the relationship between the actor and business use case, association is not give any information about which functionality it is used for.

How to Draw use case Diagram


Use case diagram of customer making payment


Generally, we have to gather requirements from the client, and those requirements we elicit and analyze, then we have to model those requirements using UML, in UML Diagrams, the use case is the mother of all Diagrams. So, using the use case we have to model the requirements.

With using MS Visio Tool, we have to draw use case diagrams

When drawing a use case diagram, we have to not mention names such as

System names, Database names, network names, software names, technology names

And we have mentioned all sequence of actions

And the proper relationship between essential use cases and supporting use cases.


Above information using we have to draw a use case Diagram.




Santhosh Pallerla


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