Page 99 - DCAP308_OBJECT_ORIENTED_ANALYSIS_AND_DESIGN

Unit 7: Interaction Modelling

Notes

Task Compare and contrast object flow and action flow.

Caselet Activity Diagram for Generating Restaurant Bill

Here, we will prepare an activity diagram for computing a restaurant bill. There should
be a charge for each delivered item. The total amount should be subject to tax and service
charge of 18% for groups of six or more. Any coupons charge submitted by the customer
is subtracted from bill.

Source: http://www.programsformca.com/2012/03/activity-diagram-for-restaurant-exam.html
Self Assessment

Fill in the blanks:
11. An .................. diagram illustrates the dynamic nature of a system by modeling the flow of
control from activity to activity.
12. .................. states represent the non-interruptible actions of objects.
13. .................. refers to the creation and modification of objects by activities.
14. A filled circle followed by an arrow represents the .................. action state.
15. .................. bar helps illustrate parallel transitions.

7.4 Summary

The purpose of Interaction diagrams is to model interactions between objects, assist in
understanding how a system (a use case) actually works, verify that a use case description
can be supported by the existing classes Identify responsibilities/operations and assign
them to classes.

A use case model is a model of how different types of users interact with the system to
solve a problem.

A use case diagram is used to graphically depict a subset of the model to simplify
communications.
An actor represents a user or another system that will interact with the system you are
modeling.
Use Cases are typically related to ‘actors’, which are human or machine entities that use or
interact with the system to perform a piece of meaningful work that helps them to achieve
a goal.
Sequence diagram is the way to explain the behaviour of a system with a view to make
interaction between the system and its surrounded environment.
Activity diagram is a variation or special case of a state machine, in which the states are
activities representing the performance of operations and the transitions are triggered by
the completion of the operations.

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