03-09-2016, 03:31 PM
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The Sequence Diagram
What is a Sequence Diagram
This diagram is a model describing how groups of objects collaborate in some behavior over time.
The diagram captures the behavior of a single use case.
It shows objects and the messages that are passed between these objects in the use case.
When to use a sequence diagram
A good design can have lots of small methods in different classes. Because of this it can be difficult
to figure out the overall sequence of behavior. This diagram is simple and visually logical, so it is
easy to see the sequence of the flow of control.
A sequence diagram also clearly shows concurrent processes and activations.
Characteristics
Represents an interaction (messages) exchanged among collaborating objects for a specific result
It shows time sequence not easily shown in a collaboration diagram
It does not show relations between objects
It can show general forms that do not deal with objects but with class interaction
Used more for real time types of applications
Creating the Sequence Diagram
You use the Sequence Diagram model to describe the aspects of your new system that change over
time. These are events that mark changes, sequences of events, and so forth. In other words, this model
is used to specify and implement the control aspects of a system. It includes time sequences but does not
include object relationships. The Sequence Diagram model allows you to graphically display various
interactions among objects as they send messages to one another over time.
The time sequence interaction is shown on this diagram. It shows the time sequence of the objects
participating in the interaction. The two dimensions of a sequence diagram consist of the vertical
dimension (time), and the horizontal dimension (different objects).
In this tutorial, you will create the Sequence Diagram using GDPro’s automatic model generation feature.
After using this feature some enhancements to the diagram are required but it requires much less effort
than starting from the beginning.
When you have completed your Sequence Diagram portion of the tutorial your model should be similar to
the following example.