You can create use case diagrams to show the interactions between the use cases and the actors in a system. You can add shapes to use case diagrams to represent the elements of the system, such as use cases and actors, and you can add connectors to show how the shapes interact.
Opening modeling diagrams
When you open a modeling diagram, it is displayed in the diagram editor. The model file, location in the model, and diagram name are displayed on the tab at the top of the diagram editor. You can have multiple diagrams open at the same time and use the tabs to navigate between the them.Adding use case diagrams to models
You can add use case diagrams to models to provide various views of the problem domain. Depending on the complexity of the system you are modeling, you can have multiple diagrams of different types in a single model.Adding diagram elements to modeling diagrams
You can add a diagram element to a modeling diagram to graphically represent a model element.Defining the boundaries of a system
A system boundary is a rectangle that you can draw in a use case diagram to separate the use cases that are internal to a system from the actors that are external to the system. A system boundary is an optional visual aid in the diagram; it does not add semantic value to the model.
Parent topic: Modeling the behavior of a system by using use case diagrams
Related concepts
Use case diagrams
Types of modeling diagrams