Guidelines:
Use-Case Diagram

Use-Case Diagram |
A use-case diagram shows actors, use
cases, use-case packages, and their relationships. |
Topics
Diagrams with actors, use cases, and relationships among them are called use-case
diagrams and illustrate relationships in the use-case model.
Use-case diagrams can be organized into (and owned by) use-case packages, showing only
what is relevant within a particular package.
There are no strict rules about what to illustrate in use-case diagrams. Show what you
think are interesting relationships in the model. The following diagrams may be of
interest:
- Actors belonging to the same use-case package.
- An actor and all the use cases with which it interacts. A diagram of this type can
function as a local diagram of the actor, and is likely to be related to it.
- Use cases that handle the same information.
- Use cases used by the same group of actors.
- Use cases that are often executed in one sequence.
- Use cases that belong to the same use-case package.
- The most important use cases. A diagram of this type can function as a summary of the
model, and is likely to be included in the use-case view.
- The use cases developed together (within the same increment).
- A specific use case and its relationships to actors and other use cases. A diagram of
this type can function as a local diagram of the use case, and is likely to be related to
it.
It is recommended that you include each actor, use case, and relationship in at least
one of the diagrams. If it makes the use-case model clearer, they can be part of several
diagrams and you can show them several times in the same diagram.
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