Interaction Diagrams

1
Interaction Diagrams

• CS 124

2
Object collaboration

• A use case carried out involves objects and
  interaction or collaboration between these
  objects
• Method calls between objects
• This collaboration is depicted in the UML through
  an Interaction Diagram
• Two types
• Collaboration diagram
• Sequence diagram

3
ExampleCollaboration Diagram
2 checkIfAvailable()
Checkout Screen
Book
1 checkIfDelinquent() 3 borrowBook()
4 setBorrower()
Borrower
4
Interaction (Collaboration) Diagram Notation

• Rectangles Classes/Objects
• Arrows Messages/Method Calls
• Labels on Arrows
• sequence number (whole numbers or X.X.X notation)
• method name (the message passed)
• more details, if helpful and necessary
  (iterators, conditions, parameters, types, return
  types)

5
Methods

• Interaction Diagrams suggest/imply methods for
  classes
• Has consequences on detailed class diagram
• The label(s) of an arrow should be a method of
  the class the arrow points to
• Library System
• Borrower class should have at least two methods
  (checkIfDelinquent and borrowBook)

6
Including Conditionsand Types
2 avail checkIfAvailable()boolean
Checkout Screen
bBook
1 delinq checkIfDelinquent()boolean 3!delinq
avail borrowBook(Book b)
rBorrower
7
Creating an Object

• new means a constructor is being called
• Implies object creation

1 addCustomer(custdetails)
CustomerList
Encoder
2 new
Note this means theaddCustomer method
willcontain code that createsa Customer object
Customer
8
Iteration

• is an iterator
• means the method is called repeatedly

1 printSalesSummary()
Store
Manager
2 getTotalSales()
Note Store needs data from all branches to
produce a summary
Branch
9
Sequence Diagram

• Variant of an interaction diagram that emphasizes
  sequence
• Objects shown as boxes on top of the diagram
• Dashed vertical line below the box objects
  lifeline
• Activation bar to indicate the objects
  activation
• Sequence number unnecessary because top to bottom
  calling sequence is assumed
• Message notation the same as for collaboration
  diagrams

10
Collaboration versus Sequence Diagrams

• Use collaboration diagrams when you want to make
  use of a two-dimensional layout of interacting
  objects
• Ok when there arent that many objects
• Use sequence diagrams when layout doesnt help in
  presentation and when you want to clarify calling
  sequence