1. UML Interaction Diagrams
Ch. 15

2. Interaction Diagram Notation

3. Introduction
Interaction diagrams illustrate how objects interact via messages.
Collaboration diagrams illustrate object interactions in a graph or network format.
message1( )
:ClassAInstance
1: message2()
2: message3()
:ClassBInstance

4. Sequence vs Collaboration Diagrams
:ClassAInstance
:ClassBInstance
message1( )
:ClassAInstance
message1()
message2()
1: message2()
2: message3()
What is the difference of collaboration vs sequence diagrams?
For which components of a sw project do we draw a sequence diagram? For which components of a sw project do we draw a collaboration diagram?
Collab: more for whiteboard vertical/horizontal expansion
Spend time doing dynamic modeling!
message3()
:ClassBInstance

5. Example Collaboration Diagram: makePayment
direction of message
first internal message
makePayment(cash Tendered)
:Register
1: makePayment(cash Tendered)
:Sale
parameter
link line
1.1: create(cash Tendered)
first message
instance
:Payment
object creation

6. How to Read the makePayment Collaboration Diagram
The message makePayment is sent to an instance of Register. The sender is not identified.
The Register instance sends the makePayment message to a Sale instance.
The Sale instance creates an instance of a Payment.
makePayment(cashTendered)
:Register
1: makePayment(cashTendered)
:Sale
1.1: create(cashTendered)
:Payment

7. Example Sequence Diagram: makePayment
:Register
:Sale
makePayment (cashTendered)
makePayment (cashTendered)
create (cashTendered)
:Payment

8. Illustrating Classes and Instances
To show an instance of a class, the regular class box graphic symbol is used, but the name is underlined. Additionally a class name should be preceded by a colon.
An instance name can be used to uniquely identify the instance.
Sale
Class
:Sale
Instance
s1:Sale
Named instance

9. Messages to “self” or “this”
A message can be sent from an object to itself.
This is illustrated by a link to itself, with messages flowing along the link.
msg1()
:Register
1: clear()

10. Creation of Instances
The language independent creation message is create, being sent to the instance being created.
The create message may include parameters, indicating passing of initial values.
msg1 ( )
1: create (cashier)
:Register
:Sale
newly created instance

11. Creation of Instances
An object lifeline shows the extend of the life of an object in the diagram.
Note that newly created objects are placed at their creation height.
:Register
:Sale
makePayment(…)
makePayment(…)
create(…)
:Payment

12. Lifelines
Synchronous vs asynchronous messages

13. Asynchronous vs synchronous calls
Async: not block or wait for response, used in multithreaded java

14. Return Values

15. Conditional Messages :A :B
message1()
[color=red] calculate()

16. Conditionals

17. Conditional Messages
A conditional message is shown by following a sequence number with a conditional clause in square brackets, similar to the iteration clause.
The message is sent only if the clause evaluates to true.
msg1 ( )
1: [new sale]
create (cashier)
:Register
:Sale
Link: connection path between two objects (straight line in comm diag.)

18. Mutually Exclusive Conditional Paths
1a and 1b are mutually
exclusive conditional paths.
Both are sequence number 1
since either could be the first
internal message.
unconditional
after either msg2()
or msg4()
:ClassE
2: msg6()
msg1 ( )
1a: [test1] msg2()
:ClassA
:ClassB
1b: [not test1] msg4()
1a.1: msg3()
:ClassD
:ClassC
1b.1: msg5()

19. Iteration or Looping
Iteration;
Recurrence values omitted
Iteration is indicated by following the sequence number with a star *
This expresses that the message is being sent repeatedly, in a loop, to the receiver.
It is also possible to include an iteration clause indicating the recurrence values.
msg1( )
1*: li := nextLineItem():
SalesLineItem
:Register
:Sale
Iteration clause
msg1( )
1*: [i :=1..10]
li := nextLineItem(): SalesLineItem
:Register
:Sale