DEV475 Mastering Object-Oriented Analysis and Design with UML ...

Module 6 - Use-Case AnalysisCollaboration Diagrams vs. Sequence DiagramsCollaboration Diagrams vs. Sequence Diagrams• CollaborationDiagrams• Show relationships inaddition to interactions• Better for visualizingpatterns of collaboration• Better for visualizing allof the effects on a givenobject• Easier to use forbrainstorming sessions• Sequence Diagrams• Show the explicitsequence of messages• Better for visualizingoverall flow• Better for real-timespecifications and forcomplex scenariosMastering Object Oriented Analysis and Design with UMLCopyright © 2003 Rational Software, all rights reserved 35Sequence diagrams and Collaboration diagrams express similar information, but showit in different ways.Collaboration diagrams emphasize the structural collaboration of a society of objectsand provide a clearer picture of the patterns of relationships and control that existamongst the objects participating in a use case. Collaboration diagrams show morestructural information (that is, the relationships among objects). Collaborationdiagrams are better for understanding all the effects on a given object and forprocedural design.Sequence diagrams show the explicit sequence of messages and are better for realtimespecifications and for complex scenarios. A Sequence diagram includeschronological sequences, but does not include object relationships. Sequencenumbers are often omitted in Sequence diagrams, in which the physical location ofthe arrow shows the relative sequence. On Sequence diagrams, the time dimension iseasier to read, operations and parameters are easier to present, and a larger numberof objects are easier to manage than in Collaboration diagrams.Both Sequence and Collaboration diagrams allow you to capture semantics of theuse-case flow of events; they help identify objects, classes, interactions, andresponsibilities; and they help validate the architecture.6 - 35