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In software and systems engineering, a use case is a potential scenario in which a system receives an external request (such as user input) and responds to it. A use case is a list of actions or event steps typically defining the interactions between a role (known in the Unified Modeling Language (UML) as an actor) and a system to achieve a goal.
A use case diagram [1] is a graphical depiction of a user's possible interactions with a system. A use case diagram shows various use cases and different types of users the system has and will often be accompanied by other types of diagrams as well. The use cases are represented by either circles or ellipses. The actors are often shown as stick ...
Use case diagrams are used to identify the actor (users or other systems) and the processes they perform. System sequence diagram : A system sequence diagram (SSD) is a picture that shows, for a particular scenario of a use case, the events that external actors generate, their order, and possible inter-system events.
It is customary to write full-text use cases during the construction phase and each one becomes the start of a new iteration. Common Unified Modeling Language (UML) diagrams used during this phase include activity diagrams, sequence diagrams, collaboration diagrams, state transition diagrams and interaction overview diagrams. Iterative ...
UML (Unified Modeling Language) is a modeling language used by software developers. [1] UML can be used to develop diagrams and provide users (programmers) with ready-to-use, expressive modeling examples. [note 1] Some UML tools generate program language code from UML. [2] UML can be used for modeling a system independent of a platform language.
UML's use case diagram provides a simple goal modeling notation. The bubbles name functional goals, [14] so a Use case diagram forms a simple functions-only goal model: as Cockburn writes, use cases cover only the behavioral requirements. [15] Roles are shown as actors (stickmen on the diagram), linked to the use cases in which they take part.
UML diagrams used to represent the physical view include the deployment diagram. [2] Scenarios: The description of an architecture is illustrated using a small set of use cases, or scenarios, which become a fifth view. The scenarios describe sequences of interactions between objects and between processes.
This diagram depicts the processes and objects involved and the sequence of messages exchanged as needed to carry out the functionality. Sequence diagrams are typically associated with use case realizations in the 4+1 architectural view model of the system under development. Sequence diagrams are sometimes called event diagrams or event scenarios.