UML Object diagram
Object diagram is used for representing a relationship between instances. In OMG UML 1.5 specification, it is defined as “a graph of instances, including objects and data values. A static object diagram is an instance of a class diagram; it shows a snapshot of the detailed state of a system at a point in time.” Analyzing the system structure using object diagram is useful in understanding class diagrams clearly.
How to draw Object diagrams in Astah?
Astah doesn’t have an independent menu of “Object diagram”, so use Class Diagram.
To create a line between InstanceSpecifications, simply select [Link] from tool bar or click “L” and draw between InstanceSpecifications, which appears when you have mouse over the InstanceSpecification then click another InstanceSpecification to connect to.
Hope this helps!