Use Case Diagram
Learn about the use case diagram and its benefits with some examples.
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Use case diagram describes the specification of users and their possible interactions with the system. These possible interactions are called use cases.
Components of a use case diagram
To understand a use case diagram, it is important to first understand its components. Use case diagrams have the following components:
Actor: Users are called actors. They interact with the system. They could be humans, machines/hardware, or other external systems. There are two types of actors:
Primary actors: These are the humans or external systems that interact with that system and are responsible for initiating the use case. They are placed on the left side in a use case diagram. Primary actors are also called active actors.
Secondary actors: These are the ones that are used by the system to assist the primary actors in a use case. They cannot interact with the system on their own. They need primary actors to initiate a use case. Secondary actors are also called passive actors, and they are placed on the right side in a use case diagram.
Use case: This is a single function performed on a system by an actor. It is represented by an oval shape.
Package: This is a group of different elements. These groups are represented inside a folder icon.
Note: This is used to add additional information about any component or relationship in a use case diagram.
The representation of the components explained above in a use case diagram is given below: