A node instance is an instance of a node where component instances (see Section 21.5) may reside. In the UML metamodel NodeInstance is a sub-class of Instance and is specifically an instance that is derived from a node.
A node instance is represented on a sequence diagram in ArgoUML as a three dimensional box labeled with the node instance name (if any) and node type, separated by a colon (:).
 | Tip |
|---|---|
It is the presence of the colon (: that distinguishes a node instance from a node. | |
 | Caution |
|---|---|
The current release of ArgoUML there is no way of specifying the node type, so it must be done in the name. This leads to the representation having two colons, one at the very end. | |
The details tabs that are active for node instances are as follows.
- ToDoItem
Standard tab.
- Properties
See Section 21.3.2 and Section 21.3.3 below.
- Documentation
Standard tab.
- Style
Standard tab. The Bounds: field defines the bounding box for the node instance on the diagram.
Warning Beware that in the current release of ArgoUML, the bounding box just refers to the front face of the cube. This means that the three dimensional top and side may be ignored, for example when determining the limits of a diagram for saving graphics.
Altering the Shadow entry has no effect.
- Source
Standard tab, containing just the name of the node instance.
Caution A node instance should not generate any code, so having this tab active is probably a mistake.
- Constraints
Standard tab. In the UML metamodel, NodeInstance has the following standard constraints defined (through its parent, Instance).
destroyed. Applied to a node instance that is destroyed during the execution.
Caution It is conceivable this could apply to some robotic systems, or where UML is being used to describe systems with human behavior. However it is unlikely to be of widespread use.
new. Applied to a node instance that is created during the execution.
Caution It is conceivable this could apply to some robotic systems, or where UML is being used to describe systems with human behavior. However it is unlikely to be of widespread use.
transient. Applied to an node instance that is both created and destroyed during the execution.
Caution It is conceivable this could apply to some robotic systems, or where UML is being used to describe systems with human behavior. However it is unlikely to be of widespread use.
- Tagged Values
Standard tab. In the UML metamodel, NodeInstance has the following standard tagged values defined.
persistence (from the superclass, Instance. Showing the permanence of the state information associated with the node instance. Values transitory (state is destroyed when the node instance is destroyed) and persistent (state is preserved when the node instance is destroyed).
Caution It is conceivable this could apply to some robotic systems, or where UML is being used to describe systems with human behavior. However it is unlikely to be of widespread use.
derived (from the superclass, ModelElement). Values true, meaning the node instance is redundant—it can be formally derived from other elements, or false meaning it cannot.
Caution It is not clear that this tagged value has any great use when applied to a node instance.
Note The UML Element metaclass from which all other artifacts are derived includes the tagged element documentation which is handled by the documentation tab under ArgoUML
Go
upNavigate up through the package structure.
Go
backNavigate back to the previous artifact.
Warning This feature is currently broken within ArgoUML and there is no guarantee where (if anywhere) this button will take you.
Go
forwardNavigate forward to the next artifact.
Warning This feature is currently broken within ArgoUML and there is no guarantee where (if anywhere) this button will take you.
DeleteThis deletes the node instance from the model
Warning This is a deletion from the model not just the diagram. To delete an node instance from the diagram, but keep it within the model, use the main menu Edit/Remove From Diagram (Ctrl-R).
- Name
Text box. The name of the node instance. By convention node instance names start with a lower case letter and use bumpy caps to divide words within the name.
Note ArgoUML does not enforce this naming convention.
Caution The current release of ArgoUML there is no way of specifying the node type, so it must be done in the name. This leads to the representation having two colons, one at the very end.
- Stereotype
Drop down selector. Node instance has no stereotypes by default in the UML standard, but ArgoUML provides the stereotypes, machine, organization and person.
Caution ArgoUML also provides the stereotype realize for node instances. This appears to be an error, since this stereotype properly belongs to the Abstraction metaclass.
- Navigate Stereotype
icon. If a
stereotype has been selected, this will navigate to the
stereotype property panel (see Section 16.4).- Namespace
Text box. Records the namespace for the node instance. This is the package hierarchy.
Button 1 click on the entry will navigate to the package defining this namespace (or the model for the top level namespace).