Creating links in collaboration diagrams

The Link tool draws a message link, or association role, between two classifier roles. Optionally, you can give the association role a name, perhaps to indicate the type of communication that occurs over this link. The association role can be an instance of an existing association between the two classes (from which the classifier roles are realized).

About this task

The association role of a link can be <Unspecified>, meaning that it is an unspecified association. This could be useful in design- and even detailed design-phase collaboration diagrams, because you can portray messages that are not passed through relations, such as communication with local or global variables (objects) or communication with variables passed as parameters of a method.

Association roles are themselves not directional, even if they are assigned a directional association. This is in keeping with the emphasis on message traffic, regardless of which class initiated the flow. Once you have created an association role, you can draw the messages that go across it.

Note: You can physically move an association role from one set of classifier roles to another, but this is not typical because the connection of the association role to the association is lost. The association of an association role must be between the classes matched to the end classifier roles.

Procedure

  1. Click the Link button Link button.
  2. Click in a classifier role.
  3. Click in another classifier role. The link is drawn between the two classifier roles, and the cursor automatically opens the association role name text box.
  4. If wanted, type a name for the association role, then press Enter.

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