An event is an observable occurrence. In the UML
metamodel it is a child of
ModelElement.
There are a number of different types of events that are children of event within the UML metamodel.
CallEvent. Associated with an operation of a class, this event is caused by a call to the given operation. The expected effect is that the steps of the operation will be executed.SignalEvent. Associated with a signal, this event is caused by the signal being raised.TimeEvent. An event cause by expiration of a timing deadline.ChangeEvent. An event caused by a particular expression (of attributes and associations) becoming true.
An event is represented by its name.
The details tabs that are active for events are as follows.
ToDoItemStandard tab.
PropertiesSee Section 20.9.2, “ Event Property Toolbar ” and Section 20.9.3, “ Property Fields For Event ” below.
DocumentationStandard tab.
StereotypeStandard tab. In the UML metamodel, an
Eventhas the following standard stereotypes defined.create(for aCallEventonly). Create is a stereotyped call event denoting that the instance receiving that event has just been created. For state machines, it triggers the initial transition at the topmost level of the state machine (and is the only kind of trigger that may be applied to an initial transition).destroy(for aCallEventonly). Destroy is a stereotyped call event denoting that the instance receiving the event is being destroyed.
Tagged ValuesStandard tab. In the UML metamodel, an
Eventhas no standard tagged values defined.
Go upNavigate up through the composition structure.
New StereotypeThis creates a new Stereotype (see Section 16.6, “ Stereotype ”) for the selected event, navigating immediately to the properties tab for that stereotype.
New parameterThis creates a new parameter for the event operation as the current parameter, navigating immediately to the properties tab for that parameter (see Section 18.9, “ Parameter ”).
DeleteThis deletes the event from the model.
NameText box. The name of the event. By convention event names start with a lower case letter and use bumpy caps to divide words within the name in the same way as operations.
![[Note]](images/note.png)
Note ArgoUML does not enforce this naming convention.
![[Tip]](images/tip.png)
Tip For call events it makes sense to use the name of the associated operation. For signal events it make sense to use the name of the signal, prefixed by
[sig]. For time events use the time expression, prefixed by[time]and for change events the change expression, prefixed by[change].NamespaceText field. Shows the namespace for the event. This is the composition hierarchy.
ParametersText area, with entries for all the actual parameter values of the event (see Section 18.9, “ Parameter ”).
Button 1 double-click on any of the parameters navigates to that parameter, button 2 click brings up a pop up menu with one entry.
New Parameter. Create a new parameter and navigate to it.
TransitionThis shows the transition caused by the event.
button 1 double-click on the transition navigates to that transition.
OperationsDrop-down selector. Only present for a Call Event. This allows specifying the operation that causes the event when called.
SignalText field. Only present for a Signal Event. This allows specifying the signal that causes the event when called.
Button 1 double-click navigates to the selected signal, button 2 gives a pop up menu with two entries.
Add.... This opens a dialog box that allows selecting an already existing signal.New Signal. Creates a new Signal, and navigates to it.
WhenDouble text field. Only present for a Time Event. This allows expressing the time that the event is called.
The first of the two fields is for the body of the expression, and the second one for the language in which it is written.
![[Warning]](images/warning.png) | Warning |
|---|---|
In ArgoUML V0.20, the properties panel of a change event lacks a field to enter the change expression. |