UML Weekend Crash Course™ - To Parent Directory

Answers to Part Reviews 323
22. Draw the logic in sequential fashion using all the activity features needed to represent
the flow properly. When you encounter the need to loop back to a previous
point, insert a diamond merge point symbol at the return point in the logic.
23. The fork bar allows you to show the point in the flow where a number of processes
begin at the same time. Each logical process is modeled independent of the other
until they meet at a synchronization bar. Meeting at the synchronization bar indicates
that each process has ended and the original initiating process continues on
its own.
24. Place a guard condition on the transition. The guard is an expression enclosed in
square brackets [ ] that must test true in order to follow the transition.
25. The objects that participate in the work. The object lifelines that allow you to represent
the order of the events. The events that express what the objects say to one
another.
26. The event is expressed as an operation that is being invoked on the other object,
using the name of the operation, the arguments, and the return type.
27. It uses a self-reference, an event that leaves the object lifelines and loops back to
the same lifeline.
28. The object usually becomes active in response to a message or signal (an event)
that tells it to start performing an operation.
29. The first represents a synchronous message, the invocation of an operation on the
object it is pointing to. The second represents a reply or the return value from
the operation that was invoked.
Saturday Evening Review Answers
1. It’s usually best to use a Use Case scenario because it is a single discrete piece of
logic. But a Sequence diagram can also be used for a single operation or just about
any other discrete piece of logic in the design.
2. Returns are drawn with a dashed line style arrow and the description of the data
being returned.
3. No. You can refer to them in a comment. The goal of the diagram is to identify the
interactions. Once identified, your goal has been achieved. Showing them more
than once is just more work with no value.
4. The activation bar is placed on the object lifeline. The activation bar begins when
an event is sent to the object and ends when the object sends back a response or
finishes the requested operation.
5. The operation signature includes the name, arguments, and return type (optional).
You may also show the sequence number and the operation visibility.
6. The Object diagram represents the structure of the objects and their relationships.
The structure is what makes the interactions possible. Using the structure, the
Collaboration diagram can validate that the messaging is taking place across
existing connections. The Collaboration diagram can also reveal the need for new
connections when an interaction is needed but not currently supported by the
structure.