AssociationsĪssociations are interactions either between an actor and a use case or between two use cases. Actors should also be labeled, but label them with their function or role, like “customer” or “user,” rather than their actual name. The only qualifications of an actor are being outside of the system and interacting with it in some way. Actors can also be organizations as a whole or even other systems. They are depicted by stick figures in the diagram, but they don’t have to be people, although they often are. ActorsĪctors are the other primary component of the use case diagram. For example, an online clothing store’s use cases would include checking out a purchase or processing a return. Use cases are the different ways that actors can interact with the system and should always be labeled with an action phrase that indicates the goal of the use case. Use cases are the main element of the use case diagram and are represented by oval shapes. To learn more about UML notation in general, check out our UML diagramming blog. Use case diagrams don’t use as many symbols as many other types of UML diagrams. Use case diagrams are also an important part of the system planning process because they allow the team to visualize the system’s functional requirements and translate them into design priorities. They are an effective tool for general functionality analysis without the need to get into the specifics of how those functionalities are implemented on a technical level. Use case diagrams are one of the least technical UML diagram types, so they are a great way to communicate high-level concepts about a system to managers or other business stakeholders. For this reason, use case diagrams are often accompanied in documentation with other technical diagram types, like sequence diagrams or activity diagrams. By visualizing all of the possible actions taken between a system and an external actor, use case diagrams are helpful for system planning and communication.ĭifferent from many other types of UML diagrams, use case diagrams do not show events as they occur in time order and are instead a more broad overview of the system. Use case diagrams are a type of UML diagram that summarize the details of a system’s function by depicting outside users’ interactions with it.

Online shopping use case diagram