Communication dialog box

Communication links

A communication link represents the interaction that a user external to the system can have with the system in specific use modes. Communication links are defined in a use case.

The dialog box for communication links is the same as that used for binary associations. It contains four tabs - "Properties", "Notes", "Tagged values" and "Stereotypes". For information on these standard dialog box tabs, please see "Standard dialog box tabs".

The "Properties" tab of the communication dialog box

The "Properties" tab of the communication dialog box is used to define values for the communication link.

The "Properties" tab of the communication dialog box

Key:

· "In the association or the aggregation": This specifies the name of the communication link.

· "The class": This defines the names of the elements at either end of the link.

· "Has the role of": This is the role played by an element with regard to the element at the opposite end of the link.

· "Quantity (min-max)": This is the interval multiplicity written "min*max". "min" gives the minimum number of instances of the class, and "max" indicates the maximum number of instances of the class. The "*" symbol means unlimited.

· "Association kind": This is used to define the kind of link concerned. "Association" is for standard associations, "Aggregation" represents "shared aggregations" (indicated by a white triangle), and "Composition" represents strong composition (graphically shown by a black triangle).

· "Is changeable": When placed on a target end, this specifies whether or not an instance of the link can be modified from the source end.

· "Is navigable": This specifies whether or not the link can be traversed from the opposite element to the element attached to the association end in question.

· "Accessible the following way": This is the visibility of the member (public, protected or private). Choosing visibility orientates the relation between the current element and the element at the other end (navigability).

· "Access mode": This determines the access mode of the link (read, write, read/write or no access).

· "Abstract": This determines if the role is abstract or not.

· "Class": This determines if the role is class or not.

· "Is ordered": This determines if the role is ordered or not.

· "Is unique": This determines if the role is unique or not.