CSSE374 Elaboration UML Interaction

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Right what you get when you google for
class. From www.backoftheclass.net/ .
CSSE374 Elaboration UML Interaction Class
Diagrams
Steve Chenoweth Day 8, Dec 12, 2008
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Today

• Project a handoff
• As designers an discussion of the req your
  customer team did
• And, youre off and running on P2 do a domain
  model for Tues 6 AM!
• Discussion - Continue Elaboration (Design)
• Finish Ch 13-14 discussion from yesterday
• start UML Interaction Diagrams Ch 15
• Maybe get to UML Class Diagrams Ch 16

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UML Interaction Diagrams

• The book alternates between showing
• UML Sequence Diagrams, and
• UML Communication Diagrams
• Well focus on Seq Dias.
• Save as a HW assignment, Whats better about the
  other alternative.

Ch 15
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Sequence Diagrams

• Like SSDs (Ch 10), but
• At a more detailed level and
• Showing internal workings
• Can lead directly to code

Step 1
public class A private B myB new
B() public void doOne() myB.doTwo()
myB.doThree() //
Step 2
Fig 15.1 Sequence diagram.
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Seq Dia NextGen POS example

• The message makePayment is sent to an instance of
  a 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.

Step 1
Fig 15.3 Sequence diagram.
Public class Sale Private Payment
payment Public void makePayment( Money
cashTendered ) payment new Payment(
cashTendered ) // //
Step 2
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Seq Dia - Advice

• Most novice modelers go for class diagrams, but
  miss doing seq dias.
• This is important because it shows the dynamics
  of the system.

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Seq Dia - Variations
Fig 15.5
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Seq Dia -Singletons

• As well see later, Singleton is an important
  software pattern.
• Only one instance of a class is allowed.
• Often implemented by making the class constructor
  private.
• Can show this in diagrams

Fig 15.6
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Synchronous Msgs

• In UML Seq Dia,
• Solid-headed arrow synch
• Open-headed arrow asynch
• Whats the difference?
• Synch waits for a reply
• Asynch typically starts or interacts with a
  separate thread

Fig 15.8 Two ways to show a return in
synchronous messages.
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Asynchronous Msgs

• Dont wait for a reply to continue execution
• Maybe you get one (eventually), maybe you dont
• The author here uses half arrowheads to show the
  asynch messages
• The Connect message starts a new thread
• The X shows destruction of an object (and thread)
• From http//www.cs.umd.edu/mvz/cmsc435-s05/pdf/ce
  ll-phone-sequence-chart.pdf.

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More Asynch
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Loops like in SSDs
Fig 15.12 Example UML frame.
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Other kinds of frames

• See pp. 231-5.
• Example alt

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How about polymorphic messages?
Fig 15.21
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UML Class Diagrams

• Static object modeling
• Can call these design class diagrams
• Much more specific than domain models

Fig 16.2 UML class diagrams in two perspectives.
Ch 16
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Fig 16.1 Common UML notation
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Typical detail - Showing collections
Fig 16.6 Two ways to show a collection attribute
in the UML.
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Typical detail Showing dependency

• This is also coupling
• Reliance on another class
• A global variable
• A parameter, local var or static method

Fig 16.9
public class Sale public void updatePriceFor(
ProductDescription description) money
basePrice description.getPrice() // //
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Typical detail Showing constraints
Fig 16.14 Constraints
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Typical detail Association class

• Treat an association as a class!

Fig 16.16
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How to get good at design?

• Practice!

gt 50 years ago, Sviatoslav Richter decides
what Chopin Etude to practice next. Picks Op 10,
No 4. From http//www.youtube.com/watch?v3azkJP_v
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