Poseidon for UML: Users Guide
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# Object Diagram

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.

## Diagram Elements

- 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.

## Toolbar

| Select
| Node
| Instance of a Node
| Component
| Port
| Instance of a Component
| Dependency
| Connector Between Ports
| Class
| Interface As Circle
| Lollipop
| Socket
| Association
| Directed Association
| Aggregation
| Composition
| Association Class
| Object
| Link
| Comment
| Connect Comment to Element
| Text
| Circle
| Rectangle
| Polygon
| Polyline
| Repaint

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