A use case represents a complete meaningful “chunk” of activity by the system in relation to its external users (actors), human or machine. It represents the primary route through which requirements are captured for the system under construction
Within the UML metamodel, use case is a sub-class of
The use case icon is an oval (see Figure 17.1, “Possible artifacts on a use case diagram.”). It may be split in two, with the lower compartment showing extension points
By default ArgoUML does not show the extension point
compartment. It may be revealed by the context sensitive
The details tabs that are active for use cases are as follows.
Standard tab. See Section 13.4, “Documentation Tab”.
Standard tab. The Fill color is used for the use case oval.
Display: Extension Points check
box is used to control whether an extension point compartment
Standard tab. It would not be usual to provide any code for a use case, since it is primarily a vehicle for capturing requirements about the system under construction, not creating the solution.
Standard tab. In the UML metamodel,
UseCase has the following standard tagged values
persistence (from the superclass,
transitory, indicating state is
destroyed when an instance is destroyed or
persistent, marking state is preserved when an
instance is destroyed.
In general the instantiation of use cases is not a major aspect of any design method (they are mostly concerned with requirements capture. For most OOA&D methodologies, this tag can safely be ignored.
semantics (from the superclass,
Classifier). The value is a
specification of the semantics of the use case.
derived (from the superclass,
true, meaning the use case is
redundant???it can be formally derived from other elements,
false meaning it cannot.
Derived use cases still have their value in analysis to introduce useful names or concepts.
Standard tab for a Classifier.
Navigate up through the package structure of the model.
New use case
This creates a new use case within the model, (but not within the diagram), and shows immediately the properties tab for that use case.
This method of creating a new use case can be confusing. It is much better to create a new use case on the diagram of your choice.
New extension point
This creates a new use extension point within the namespace of the current use case, with the current use case as its associated use case, navigating immediately to the properties tab for that extension point.
This deletes the selected use case from the model.
This is a deletion from the model
not just the diagram. To delete a use
case from the diagram, but keep it within the model, use the
Text box. The name of the use case. Since a use case is
a classifier, it would be conventional to Capitalize the first
letter (and initial letters of any component words), e.g.
RemoteSensor. The name is shown inside the
oval representation of the use case on the diagram.
ArgoUML does not enforce any naming convention for use cases
Drop down selector. Use case is provided by default with
the UML standard stereotypes (
classifiers. Stereotyping can be useful when creating use
cases in the problem domain (requirements capture) and
solution domain (analysis), but none of the predefined
stereotypes are well suited to this.
icon. If a stereotype has been selected, this will navigate to the stereotype property panel (see Section 16.5, “Stereotype”).
Text box. Records the namespace for the use case. This is the package hierarchy.
Check box, with entries
Abstract is used to declare that
this actor cannot be instantiated, but must always be
Leaf indicates that this use case
can have no further children, while
Root indicates it is a top level use
case with no parent.
Text box. If this use case is, or can be extended, this field lists the extension points for the use case.
Extension points are listed by their location point rather than their name.
Where an extension point has been created (see below), button 1 Double Click will navigate to that relationship. Button 2 gives a pop up menu with one entry.
New. Add a new extension point
and navigate to it, making this use case the owning use
case of the extension point.
Text area. Lists use cases which are generalizations of this one. Will be set whenever a generalization is created on the from this Use Case. Button 1 Double Click on a generalization will navigate to that generalization.
Text box. Lists any specialized use case (i.e. for which this use case is a generalization.
Button 1 double click navigates to the generalization and opens its property tab.
Text box. Lists any class that is extended by this use case.
Where an extends relationship has been created, button 1 double click will navigate to that relationship.
Text box. Lists any use case that this use case includes.
Where an include relationship has been created, button 1 Double Click will navigate to that relationship.
Text box. Lists any association ends (see Section 18.11, “Association”) of associations connected to this use case.
Button 1 double click navigates to the selected entry.