Link Specification--General Tab

Figure 77 Link Specification--General Tab

Refer to the descriptions in the Introduction to Specifications chapter for information on the specification elements not covered in the following section.

Assoc

The Assoc field lists any valid role(s) or association(s) tied to the classes belonging to the two objects.

Select an association from the drop-down list. The name of the role tied to the association is displayed beside the link on the diagram. The keys are displayed in brackets under the role, and the constraints are displayed in braces under the keys.

Supplier and Client Visibility

Visibility is the ability of one object to see another object.

You can specify the following visibility types for the supplier object, the client object or both.

Table 13 Supplier and Client Visibility Options

Type	Description
Unspecified (Default)	The object visibility has not been specified.
Field	The supplier object is visible because it is a field of the client.
Parameters	The supplier object is visible to the client because it is a parameter for one of the client's operations.
Local	The supplier is local to an operation of the client object.
Global	The supplier object is global to the client.

An object visibility adornment is a letter inside a box placed at the supplier end of the link. Each letter identifies the type of visibility used. The adornment box is either open (shared) or filled (unshared).

You can set link visibility through the Link Specification or through the shortcut menu. These fields correspond to visibility adornments displayed in the collaboration diagram.

• To set visibility for the supplier object, click a visibility type in the Supplier Visibility section.
• To set visibility for the client object, click a visibility type in the Client Visibility section.

The visibility adornment is placed at the appropriate end of the link. The unspecified object visibility does not have a corresponding visibility adornment. Use this adornment only when you need to document an important tactical decision.

Shared

If visibility is an important detail in your software model, use visibility adornments to show these details in a collaboration diagram.

Shared visibility indicates structural sharing of the given object; that is, the shared object's state can be altered through more than one path. Unshared visibility represents unique access given to the client object. When you create a link, unshared visibility is the default.

You can set the shared indicators in the Link Specification or by selecting a visibility value from the shortcut menu.

To toggle the shared indicator, select or clear the Shared check box below the appropriate visibility section.

• If you select the Shared check box, the visibility adornment changes from a filled square to an open square of the corresponding type.
• If you clear the Shared check box, the visibility adornment changes to a filled square of the corresponding type.

Role

This field lists the role names tied to the selected associations. This is especially useful since many associations are not named. This field cannot be edited.

Note: The Link to Self Specification contains only the Name, Visibility, and Shared elements.