View source for OCUP2F 07 Sequence Diagram

[[Category:Private]]
[[Category:OCUP2]]
==Module 7. Sequence Diagram⌘==
===Interaction⌘===
* Interactions are units of behavior of an enclosing Classifier. 
* Interactions focus on the passing of information with Messages between the Connectable Elements of the Classifier.
* 4 interaction diagrams in UML 2.5:
** '''Sequence diagrams''' - sequence in which messages are exchanged 
** '''Communication diagrams''' - relationship between the participants
** '''Timing diagrams''' - state changes of the participants relative to the time
** '''Interaction overview diagrams''' - order of interactions in an activity-like notation

===Sequence Diagram⌘===
[[File:SimpleSequenceDiagram.png]]
* Participants are represented by lifeline - a rectangle and a dashed line
* Messages are represented by arrows between lifelines
* Lifeline describes the time-line for a process, where time increases down the page
* The entire diagram represents one interaction
====Connectable Element⌘====
[[File:Lifeline.png]]

Connectable Element
* a set of instances
* can be considered as objects of the specified type
* lifelines (participants) represent connectable elements (properties)
* If the referenced part has a multiplicity > 1, then the lifeline may have selector that specifies which particular part is represented by this lifeline

====Occurrence Specification ⌘====
[[File:ClipCapIt-141201-153100.PNG]]
* Occurrence Specification represents a moment in time at the beginning or end of a message or at the beginning or end of an execution.
* The semantics of an Interaction is given as a trace (a sequence of event occurrences).

====Execution Specification ⌘====
[[File:ExecutionSpecification.png]]
* Specification of the execution of a unit of behavior within the lifeline.
* Sending and receiving messages determine start and end of execution specification.

====Message⌘====
[[File:SequenceDiagramMessage.png]]

===Message Types⌘===
* '''Synchronous message''' (filled arrowhead):
** caller waits until called behavior terminates
** '''reply message''' is represented by dashed line with either an open or filled arrow head
* '''Asynchronous message''' (open arrowhead):
** caller doesn't wait but continues after call, no reply
* '''Found message''' (open arrowhead originating from a filled circle):
** receiver known, sender not known
* '''Lost message''' (open arrowhead pointing to a filled circle)
** sender known, receiver not known
* '''Create message''' (dashed line with open arrowhead pointing to header of lifeline):
** new lifeline is created at this point in the diagram
* '''Delete message''' (open arrowhead):
** object destruction, stop (destruction of an object is represented by a cross on the lifeline)

====Event Occurrences⌘====
[[File:SequenceEventOcc.png]]
* '''Sequence of event occurrences''' (trace) is defined by '''<eventoccurrence1, eventoccurrence2, ...,eventoccurrence-n>'''
* send event is denoted by an exclamation mark ('''!p''')
* receive event is denoted by question mark ('''?p''')
* A valid sequence for the interaction: '''< !p, ?p, !q, ?q >'''
* '''It's not the only valid sequence!'''

====Event Occurrences valid trace⌘====
[[File:SequenceEventOcc2.png]]

====Event Occurrences Rule⌘====
* '''Send''' event '''before receive '''event
* The order of events along one lifeline is '''relevant'''. 
* The position of one event relative to an event on another lifeline is '''insignificant'''.

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