Object diagrams show classes at the instance level.
Since objects are not on the same conceptual level as classes, although
very closely related, they are expressed in separate diagrams. On the other
hand, objects are on the same conceptual level as instances of components
and instances of nodes. That's why Poseidon for UML combines the functionality
for creating object diagrams, component diagrams and deployment diagrams into
a single editor. Therefore, to create an object diagram, use the editor for
the deployment
diagram
This may not seem very intuitive at first, but we found it to be very useful. Objects, component instances and node instances can thus be used conjunctively. You can still restrict yourself to use only objects and their links in a deployment diagram.
The diagram elements and toobar options are provided here for quick
reference. A much more comprehensive look at the editor is provided in the
section on deployment
diagrams.
Nodes and
Instances of Nodes — Nodes
represent the hardware elements of the deployment system.
Components and
Instances of Components —
Components stand for software elements that are deployed to the hardware system.
Links — Links are used to connect instances of
nodes or objects.
Dependencies — Dependencies exist between components
and can be specified by utilizing predefined or user-defined stereotypes.
Associations — Associations are used to display
communication relations between nodes. They can be specified by utilizing
predefined or user-defined stereotypes.
Objects,
Classes,
Interfaces — Components
and nodes can include objects, classes or interfaces.