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Generalizations are depicted as a close-headed arrow with the arrow pointing towards the more general modeling element.įigure 3. An association between an actor and a use caseĪssociations are depicted as lines connecting two modeling elements with an optional open-headed arrowhead on one end of the line indicating the direction of the initial invocation of the relationship.There are several types of relationships that may appear on a use case diagram: Introduce an Actor Called “Time” to Initiate Scheduled Events.Associate Each Actor With One Or More Use Cases.Name Actors With Singular, Business-Relevant Nouns.

Draw Actors To The Outside Of A Use Case Diagram.

Place Your Primary Actor(S) In The Top-Left Corner Of The Diagram.

Implying timing considerations between use cases.Īn actor is a person, organization, or external system that plays a role in one or more interactions with your system (actors are typically drawn as stick figures on UML Use Case diagrams). As you see in Figure 1, the use cases that typically occur first are shown above those that appear later.įigure 1.

Imply Timing Considerations By Stacking Use Cases.

Place Your Primary Use Cases In The Top-Left Corner Of The Diagram.

Name Use Cases Using Domain Terminology.Use Case Names Begin With a Strong Verb.A use case is drawn as a horizontal ellipse on a UML use case diagram, as you see in Figure 1. There are guidelines for:Ī use case describes a sequence of actions that provide a measurable value to an actor. Use case models should be developed from the point of view of your stakeholders and not from the (often technical) point of view of developers. Within most use case models the use case specifications tend to be the primary artifact with use case diagrams filling a supporting role as the “glue” that keeps your requirements model together. Model your analysis of your usage requirements in the form of a system use case model>Ī use case model is comprised of one or more use case diagrams and any supporting documentation such as use case specifications and actor definitions.Communicate the scope of a development initiative.Provide an overview of all or part of the usage requirements for a system or organization in the form of an essential model or a business model.

A use case diagram is “a diagram that shows the relationships among actors and use cases within a system.