Modeling Scenarioswith Sequence Diagrams

Mustafa K. Isik

April 23rd, 2007

Scenario - Definition

• sequence of processing steps

• to be executed under certain circumstances

• defined goal

• begins with a triggering event

• ends by completing task successfully or failing

Scenario - Definition (2)

• can document business processes (n : 1)

• visualization of a specific execution instance of the respective business process

• two fundamental description categories

• successful execution of a process

• failed execution of a process

UML - Visualization of dynamic activities

• Object Diagram

• system snapshot on object level, not suitable for modeling scenarios

• Communication Diagram (formerly known as Collaboration Diagram)

• models object collaboration during operation execution

• Sequence Diagram

• precise depiction of chronological execution order

Sequence Diagram

• precise description of activities

• permits for discussion of technical correctness

• suitable as means for design and implementation communication

• emphasizes chronological aspect of dynamic behavior

Sequence Diagram - Components

objName : ClassName Object

life line

Xend of life

Sequence Diagram - Components (2)

activationbar (optional)

objA : ClassName objB : ClassName

message(parameter)

Sequence Diagram - Messages / Actions

<<create>>

<<destroy>>X

obj : Class

synchronous

asynchronous

Return (opt.)

Instantiation

Dereferencing

Exampleorder : OrderControl

checkCredit()

card : CreditCard

chk : CardChecker

<<create>>

charge(card)

<<destroy>>X

Literature

• Balzert, H 2000, Lehrbuch der Softwaretechnik - Software-Entwicklung, 2. Aufl., Spektrum Akad. Verlag, Heidelberg, Chapter 2.9.5

• Pilone, D 2004, UML Kurz & Gut, O’Reilly, S. 64 - 68

• Hamilton, K, Russell, M, 2006, Learning UML 2.0, O’Reilly, Chapter 7