Specifying Particular Interacting Objects

Unless otherwise specified, any object in the origin's object class can interact with any object in the destination's object class. Sometimes we wish to place additional constraints on which particular objects in the origin or destination class will take part in the interaction. We specify these constraints on the diagram using a 'TO:' and/or 'FROM:' clause written near the interaction symbol. The clause contains all the information necessary to identify which specific objects will interact.

Suppose we are modelling an interaction taking place between a customer service representative and one of their customers. The interaction that takes place is a telephone call to verify an order. Without the clauses, the interaction will take place between any of the objects in the customer service representative class and any object in the customer class. With the clauses, we constrain it to take place between the particular customer whose name appears on the invoice and the particular customer service representative who has been assigned to that customer's state.

The diagram below illustrates the use of the 'TO: / FROM:' clause.

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Created Sat Oct 15 12:15:10 1994 ...
Updated Tue Nov 1, 1994
by Sean Rohead (rohead@bert.cs.byu.edu)