Use Case realization How classes collaborate to realize use cases or system functionality

Analysis class diagrams Tells a story about the system Generic and valid for all implementations Involves classes and associations Describes the nature of interaction between classes Described using roles played by classifier

Interaction diagrams Describes object (instance) interaction Specifically describes how the objects collaborate and interact Collaboration diagram – describes structured relationships between objects Sequence diagram – describes time- ordered sequence of messages between objects

Collaboration is a static set of relationships between instances Interaction is a dynamic interaction – including specific messages Collaboration: Object A has a role with B Interaction: A plays with B, A studies with B, A …. with B Descriptor form – describes roles played by instances Shows - Context in which interaction may occur Instance form of collaboration diagram is between objects and has links

Class Diagram –Manager class has an association (named boss) to Supervisor Object Diagram: Collaboration –Peter:Manager has links to Jack:Supervisor –Assigntask, employ, and assist can be part of the boss role Object Interaction Diagram – for use-cases Peter object first requests addschedule(..) to ManageSchedule which then does updateschedule(..) to Jack object

Messages can be sent to multi-object. Messages sent to oneself are self- delegating requests One can depict branching and iterations as well Object creation and disposal are also shown when appropriate Concurrent objects are shown in bold boxes Object states can be clarified with curved edge boxes.

Sequence Diagram Similar to Object Interaction Diagram Shows a sequence of interactions involved in a use-case Objects are laid left to right and events are depicted top to bottom as they occur.

Activity Diagram Similar to flow chart – except uses OO elements It is a diagrammatic representation of the algorithm – and hence corresponds to the source code. Activity can be deemed atomic (can’t be broken down), uninterruptible, or instantaneous You have a start state and stop state

Decisions during activity Concurrent activity Flow of outputs from one activity to another can also be shown Sending and reception of signals (asynchronous communication of information) can also be represented

Which one to use? Collaboration diagram emphasize collaboration between objects. And roles played by instances Sequence diagram emphasize the interaction as time ordered sequence of messages between instances These two are isomorphic Activity diagrams are OO flow charts – models a process