1 / 22

System Sequence Diagrams

System Sequence Diagrams. Recap. When to create SSD? How to identify classes/instances? Use case descriptions UML notations for SSD. Contents. Interaction diagrams UML notation Examples. Interaction Diagrams. Show how objects interact with one another

waynewhite
Download Presentation

System Sequence Diagrams

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript


  1. System Sequence Diagrams

  2. Recap • When to create SSD? • How to identify classes/instances? • Use case descriptions • UML notations for SSD

  3. Contents • Interaction diagrams • UML notation • Examples

  4. Interaction Diagrams • Show how objects interact with one another • UML supports two types of interaction diagrams • Sequence diagrams • Collaboration diagrams

  5. Sequence Diagrams • AKA Interaction Diagrams – Semantically equivalent to Collaboration Diagrams • Dynamic Model relating use cases and class diagrams • Illustrates how objects interacts with each other • Shows time ordering of interactions • Generally a set of messages between collaborating objects • Ordering of objects not significant

  6. Sequence Diagrams • Show only one flow of control • Can model simple sequential flow, branching, iteration, recursion and concurrency • May need multiple diagrams • Primary • Variant • Exceptions

  7. UML sequence diagrams • sequence diagram: an "interaction diagram" that models a single scenario executing in the system • perhaps 2nd most used UML diagram (behind class diagram) • relation of UML diagrams to other exercises: • CRC cards -> class diagram • use cases -> sequence diagrams

  8. Key parts of a sequence diag. • participant: an object or entity that acts in the sequence diagram • sequence diagram starts with an unattached "found message" arrow • message: communication between participant objects • the axes in a sequence diagram: • horizontal: which object/participant is acting • vertical: time (down -> forward in time)

  9. Lifeline Sequence Diagram (Basic) Object : Class or Actor name Focus of Control/ Activation message Object Destruction/ Termination X <<create>> <<destroy>>

  10. :Scheduler Student Sequence Diagram (Basic) aClass: Class Register adjustRoom checkRooms

  11. *[Iteration Condition] recursion Sequence Diagrams (Advanced) Seq# [Guard] *[Iteration] Return-List := Operation-Name (Argument-List) Conditional Lifeline {transient}

  12. Sequence Diagram(make a phone call) Caller Phone Recipient Picks up Dial tone Dial Ring notification Ring Picks up Hello

  13. A Create B X Return Deletion Lifeline Sequence Diagrams – Object Life Spans • Creation • Create message • Object life starts at that point • Activation • Symbolized by rectangular stripes • Place on the lifeline where object is activated. • Rectangle also denotes when object is deactivated. • Deletion • Placing an ‘X’ on lifeline • Object’s life ends at that point Activation bar

  14. Sequence diag. from use case

  15. Lifetime of objects • creation: arrow with 'new' written above it • notice that an object created after the start of the scenario appears lower than the others • deletion: an X at bottom of object's lifeline • Java doesn't explicitly delete objects; they fall out of scope and are garbage-collected

  16. Representing objects • squares with object type, optionally preceded by object name and colon • write object's name if it clarifies the diagram • object's "life line" represented by dashed vert. line

  17. Messages between objects • message (method call) indicated by horizontal arrow to other object • write message name and arguments above arrow

  18. Messages between objects • dashed arrow back indicates return • different arrowheads for normal / concurrent (asynchronous) methods

  19. Example

  20. Example

  21. Example

  22. Summary • SSD revision • Loops • Conditions in SSD

More Related