An interface is a set of operations characterizing the
behavior of an element. It can be usefully thought of as an
abstract class with no attributes and no non-abstract
operations. In the UML metamodel it is a sub-class of
Classifier and through that
GeneralizableElement.
An interface is represented on a class diagram as a
rectangle with two horizontal compartments. The top compartment
displays the interface name (and above it
«interface») and the second any operations. Just like
a class, the operations compartment can be hidden.
The details tabs that are active for interfaces are as follows.
ToDoItemStandard tab.
PropertiesSee Section 18.16.2, “ Interface Property Toolbar ” and Section 18.16.3, “ Property Fields For Interface ” below.
DocumentationStandard tab. See Section 13.4, “ Documentation Tab ”.
PresentationStandard tab. The tick box
Display Operationsallows the operation compartment to be shown (the default) or hidden. This is a setting valid for only the current diagram. TheBounds:field defines the bounding box for the package on the diagram.SourceStandard tab. This contains a template for the interface declaration and declarations of associated interfaces.
Tagged ValuesStandard tab. In the UML metamodel,
Interfacehas the following standard tagged values defined.persistence(from the superclass,Classifier). Valuestransitory, indicating state is destroyed when an instance is destroyed orpersistent, marking state is preserved when an instance is destroyed.![[Warning]](images/warning.png)
Warning Since interfaces are by definition abstract, they can have no instance, and so this tagged value must refer to the properties of the realizing class.
semantics(from the superclass,Classifier). The value is a specification of the semantics of the interface.derived(from the superclass,ModelElement). Valuestrue, meaning the interface is redundant -it can be formally derived from other elements, orfalsemeaning it cannot.![[Note]](images/note.png)
Note Derived interfaces still have their value in analysis to introduce useful names or concepts, and in design to avoid re-computation.
Note The UML
Elementmetaclass from which all other model elements are derived includes the tagged elementdocumentationwhich is handled by the documentation tab under ArgoUMLChecklistStandard tab for an Interface.
Go upNavigate up through the package structure.
New operationThis creates a new operation (see Section 18.8, “ Operation ”) within the interface, navigating immediately to the properties tab for that operation.
New receptionThis creates a new reception, navigating immediately to the properties tab for that reception.
New interfaceThis creates a new interface in the same namespace as the selected interface, navigating immediately to the properties tab for the new interface.
New StereotypeThis creates a new Stereotype (see Section 16.6, “ Stereotype ”) for the selected interface, navigating immediately to the properties tab for that stereotype.
DeleteThis deletes the interface from the model
Warning This is a deletion from the model not just the diagram. To delete an interface from the diagram, but keep it within the model, use the main menu
Remove From Diagram(or press the Delete key).
NameText box. The name of the interface. The name of an interface has a leading capital letter, with words separated by “bumpy caps”.
Note Unlike classes, the ArgoUML critics will not complain about interface names that do not have an initial capital.
StereotypeDrop down selector. Interface is provided by default with the UML standard stereotypes for the parent meta-class,
Classifier(metaclass,powertype,process,threadandutility).Navigate Stereotype
icon. If a stereotype has been selected, this will
navigate to the stereotype property panel (see
Section 16.6, “
Stereotype
”).NamespaceDrop down selector. Records and allows changing the namespace for the interface. This is the package hierarchy.
ModifiersCheck box, with entries
Abstract,LeafandRoot.Abstractis used to declare that this interface cannot be instantiated, but must always be specialized. The name of an abstract interface is displayed in italics on the diagram.![[Caution]](images/caution.png)
Caution This is meaningless, since by definition an interface is an abstract entity. The UML 1.3 standard offers no clarification.
Leafindicates that this interface cannot be further specialized, whileRootindicates it can have no generalizations.
VisibilityRadio box, with three entries
public,protected,privateandpackage. Indicates whether navigation to this end may be by: i) any classifier; ii) only the source classifier and its children; or iii) only by the source classifier.GeneralizationsText area. Lists any interface that generalizes this interface.
Button 1 double click navigates to the generalization and opens its property tab.
SpecializationsText box. Lists any specialized interface (i.e. for which this interface is a generalization.
Button 1 double click navigates to the generalization and opens its property tab.
AssociationEndsText box. Lists any AssociationEnds (see Section 18.13, “ Association End ”) connected to this interface.
Note Associations between classes and interfaces must be navigable only from the class to the interface. ArgoUML will create associations between classes and interfaces with the correct navigability, but does not prevent the user from altering this.
Button 1 double click navigates to the selected entry.
OperationsText area. Lists all the operations (see Section 18.8, “ Operation ”) defined on this interface. Button 1 double click navigates to the selected operation. Button 2 click will show a popup menu with two items:
Move UpandMove Down, which allow reordering the operations.Caution All operations on an interface must be public. The ArgoUML critics will complain if this is not the case.