Rational Rose Tools Interview Questions
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Collaboration Diagrams
Collaborations are more complex to follow rather than sequence diagrams, but they provide the added benefit of higher flexibility in terms of spatial layout.
Given above is a collaboration diagram for our logon interaction. You can probably notice that each of the messages is numbered in an order. This is because it is not obvious from the diagram, what the order of the messages is .
Lollipop Interfaces
Another advantage which can be given for the collaboration diagrams over the sequence diagram is that the former allows to show lollipop interfaces.
Lets say that our DatabaseAccess class implemented an interface which is called Queryable. In case the logon manager has access only to the interface, we can show that the message is being called through the interface by including a lollipop interface on the diagram. The stick of the lollipop indicates that the class DatabaseAccess realizes Queryable.
Putting it all Together
With the use of diagrams, the sequence of operation calls among objects used to complete a single use case can be clarified. While drawing these diagrams, you should try to keep them as clear and simple as possible. Sequence diagrams may be easy to read and follow, as they enforce a more standard layout on the diagram. Collaboration diagrams have the added benefit of interfaces and the freedom of layout, but they can be difficult to follow, understand and create.
It's important also not to confuse interaction diagrams with state and activity diagrams. Interaction diagrams are used in order to diagram a single use case. If you want to examine the behavior of a single instance over time then you should use a state diagram, and In case you want to have a look at the system behavior over time then you should use an activity diagram.
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