Sequence Diagrams

1
Sequence Diagrams

• CS2335
• Summer 2005

2
Agenda

• Sequence Diagrams
• Symbology
• Lab 3 Seq Diagram

3
Sequence Diagrams

• AKA Interaction Diagrams Semantically
  equivalent to Collaboration Diagrams
• Dynamic Model relating use cases (scenarios) and
  class diagrams
• Shows time ordering of interactions
• Generally a set of messages between collaborating
  objects
• Ordering of objects not significant, ordering of
  messages is.

4
Sequence Diagrams

• Show only one flow of control
• May need multiple diagrams
• Primary
• Variant
• Exceptions
• Two Levels
• System
• Class

5
Sequence Diagram (Basic)
Swimlane
anObject Class
message_name
Focus of Control/ Activation
Object Destruction/ Termination
X
new
ltltcreategtgt ltltdestroygtgt
name
Unspecified Source (trigger)
6
System Level Example
Register
Status
7
Class-Level Example
aClass
Scheduler
register
adjustRoom
checkRooms
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Sequence Diagrams (Advanced)
Return-Value Operation-Name
(Argument-List) ReturnType
for static method calls
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Sequence Diagrams (Advanced) Example
Order
careful Distributor
regular Distributor
dispatch
for each line item
loop
value gt 10,000
alt
dispatch
else
dispatch
aMessenger
new
10
Sequence Diagram (Hints)

• Each diagram or set of diagrams represents 1
  scenario.
• Use multiple diagrams to show variations like
  exceptions/failures
• Sequences start with a trigger (usually an
  external actor).

11
Lab 3 Sequence Exercise