Interaction Diagrams
CSCI 4320
Interaction Diagrams
Two Types of Interaction diagrams defined in UML
• Collaboration Diagram
– Emphasizes the structural organization of objects that
send and receive messages via the method invocation
• Sequence Diagram
– Emphasizes the time ordering of those messages
Collaboration Diagram
• Shows the objects as well as the messages that
are sent in a specific scenario
• Objects are arranged to show message passing
with a minimum of crossed lines
• Example: Show a particular Patron object
checking out a particular Resource object along
with the methods that must be invoked to allow
the checking out to occur.
Patron Checking Out Resource
ArgoUML 0.10.1
Sequence Diagram
• Shows the lifeline of when an object is created and
activation box of when the object is active.
• Shows the flow of messages unambiguously
• Vertical progression from the top of a sequence
diagram to the bottom represents the progression of
time.
• Example: Shows the order in which methods must
be invoked so that the Patron object can check out
the Resource object
Patron Checking Out Resource
ArgoUML 0.10.1
Creating Your Sequence Diagram
• ArgoUML – Collaboration and Sequence
features are not active in latest version
• Use the old version of ArgoUML 0.10.1
– This implementation is however not faithful to
UML, nor to the look and feel of the rest of
ArgoUML
• Download Version 0.10.1 (ZIP file)
http://argouml.tigris.org/servlets/ProjectDo
cumentList?folderID=330
Evaluating Design
• Reasons for modeling software before
embarking on writing code
– To produced well-structured, modular and
correct code requires some planning.
– Models allow us to evaluate the quality of the
proposed solution without too large an
investment of effort.
– A sequence diagram that models a scenario
may highlight some potential data
inconsistencies
Objectives of the Class Design
Phase
• Code Reuse
• Well-designed Classes and methods
• Assurance of data integrity
Code Reuse
• Do any classes intuitively form an inheritance hierarchy?
– Software, Book, Resource
– Savings, Checking, Account
• Reuse instead of reinvent mechanisms for interaction
– readString(length) used by readTitle() and readArtist()
• Can classes share methods through a common abstract
base class
– Both GalleryPainting and AuctionedPainting use getTitle(),
getArtist(), getSubject(), getHeight(), getWidth()
– Create abstract base class Painting
Well-Designed Classes and Methods
• Always keep data private
• Always initialize data in a constructor
• Do not use too many related primitive types.
– Create an aggregate class
– Use Address class, rather than several attributes like
street, city, zip
• Not all attributes need individual
accessor/mutator (get/set) methods
• Name classes, methods and attributes to be
self-documenting
Data Integrity
• Dirty Data: data that is inaccurate, outdated, or missing
• Potential vulnerability stems from updating interrelated
information in separate transactions or method invocations
• Interrelated Information
– Multiple data values that must be updated together in order to
maintain data integrity
– Example: When a Patron borrows a Resource both the Patron and
the Resource object must be updated with similar information
(DueDate)
• Data integrity is at risk by malicious or inappropriate user
access
Things You Should Know
• Compare and contrast collaboration and
sequence diagrams
• What are ways to support code reuse?
• What are some rules to follow to create
well-defined classes?
• Describe a situation in which data Integrity
can be compromised.