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.