The Sequence diagram focuses on the Message interchange between various Lifelines.
A Sequence diagram shows the interaction information with an emphasis on the time sequence. The diagram has two dimensions: the vertical axis representing time. and the horizontal axis representing the participating objects. The time axis could be an actual reference point, by placing the time labels as text boxes. The horizontal ordering of the objects is not significant to the operation, and you can rearrange them as necessary.
There are two Sequence Diagram modeling approaches:
- Activation bars as the lifelines.
- AVAILABLE FROM 19.0 SP1 Activation bars as the Execution Specifications (new modeling approach).