Association (dictionary item)

Model Parts, Diagrams, Dictionary Items, and Properties > Dictionary items > Association (dictionary item)

For automation interface information about an Association, see Association (automation interface).

An Association models a static and structural relationship between Actors, Classes, Data Types, Interfaces, Signals and Attributes (parts and ports) and Roles (parts and ports). An Association is assumed to be bi-directional unless an association arrow represents traversal direction. Note that traversal direction is a reflection of policy, it is does not indicate how the association is to be implemented.

Name direction shows the direction in which the association is to be read. Sometimes this is obvious and can be omitted.

Each Association must have a Role for each end of the Association. It is not necessary to name the Role and hence show the Role on the diagram. Role names are similar to Association direction names except that nouns are used instead of verbs, for example "Controller" instead of "Controls". Use of Role names and direction names on the same diagram is not recommended as this clutters the diagram with overlapping information.

You create an Association through the Class Diagram and Composite Structure Diagram. The View Options on the Class Diagram and Composite Structure Diagram allow you to either show or hide the Name and Role Name of an Association. In addition, on the Composite Structure Diagram you can show or hide the Multiplicity.

Note that when a Class Diagram shows an association or composite aggregation symbol starting from an Activity, that link symbol represents a Call Behavior Action, Central Buffer, Data Store, Input Pin or Output Pin, rather than an Association dictionary item. For more information, see the following topics:

• Creating a composite aggregation between two activities on a class diagram

• Showing an activity call tree on a class diagram

• Showing an association between an activity and a class on a class diagram

On a Composite Structure Diagram, you can create Associations as shallow or deep. Unless you have a good reason to do otherwise, always create Shallow Associations. For more information about shallows and deep Associations, see Shallow and deep associations.

Modeler can create an Association as a redefinition of another Association. For more information, see Overview of association redefinitions.

When used on a Class Diagram or Composite Structure Diagram, an Association's notation is as follows:

	Association name and arrow showing direction (can be hidden by View Options).
	Redefinition's Association type shown after colon (Composite Structure Diagrams only - can be hidden by View Options).
	Type is start-end or end-start.
	Type is bi-directional.
	Shown as binding through View Options (Composite Structure Diagram only).
	Type is none.
	Association is an aggregation.
	Association is a composite aggregation.
	Multiplicity of zero or one (can be hidden on Composite Structure Diagram).
	Multiplicity of zero or more (can be hidden on Composite Structure Diagram).
	Multiplicity of only one (can be hidden on Composite Structure Diagram).
	Multiplicity of one or more (can be hidden on Composite Structure Diagram).
	Multiplicity of tbd; to be decided (can be hidden on Composite Structure Diagram).
	User defined multiplicity, in this case 63 (can be hidden on Composite Structure Diagram).
	Role name (can be hidden by View Options)
	Qualifier name (Class Diagram only)

For information about the View Options available for this symbol, see Association view options - class diagram, and Association view options - composite structure diagram.

In the Modeler panes, a short-cut symbol

on the Association's icon indicates that the item is a stub. For more information, see Stubs.

The access permissions you have to an Association are determined by the access permissions you have to the item at the start end of the Association.

• If you select the Associations folder in the Dictionary pane, the Contents pane displays the following information about each Association in the model: Aggregation, Start Class, Start Role, End Class and End Role.

• You can move the start or end of an Association to any Class, Data Type, Interface or Signal on a Class Diagram or Composite Structure Diagram.

The following sections provide information about how an Association is used in the model. For more information about a property, item, model part or diagram, click it.

Properties

In addition to the standard properties an Association has these properties:

• Aggregation (Aggregate through the automation interface)

• Association Type (Navigation through the automation interface) - Specifies Start-End, End-Start, Bi-directional, or None.

• Composite Aggregation

• Multiplicity (Start Multiplicity Text or Start Multiplicity Uml, and End Multiplicity Text and End Multiplicity Uml through the automation interface)

• Name Direction

• The multiplicity of an Association is defined through the drop-down list boxes on the Start Role and End Role tabs of an Association's Property Pages.

• The In Role box on the Start Role and End Role tabs of the Property Pages specifies the name of the linked Role.

• The When Qualified By box on the Start Role and End Role tabs of the Property Pages specifies the name of the linked Qualifier.

Owned by

Actor

Attribute (as Part or Port)

Class

Data Type

Interface

Role (as Part or Port)

Signal

An Association is owned jointly by the two items it links, that is, if either item is deleted the Association is deleted as well. The access permissions you have to an Association are determined by the access permissions you have to the item at the start end of the Association.

Owns

Comment

Constraint

Dependency - The Dependency is owned jointly by the Association and the other associated item. The access permissions you have to a Dependency are determined by the access permissions of the dependent item.

IO Flow

Qualifier

Defined in these parts of the model

Class Model

Shown on these diagrams

Class Diagram

Composite Structure Diagram

Variant Diagram

For information about how the View Options affect the presentation of Associations, see Association view options - class diagram, and Association view options - composite structure diagram.

Can be linked to these dictionary items

IO Flow - An IO Flow can be realized by an Association.

Role - The linked Roles specify the start and end roles for the Association. Note that the name of the linked Roles appears in the In Role boxes on the Start Role and End Role tabs of an Association's Property Pages.

Stereotype

Like most other items in a Model, an Association can be linked to an Activity Partition, Comment, Frame Box, General Node, General Flow, General Flow Diagram Node, Constraint (applied), General Flow Diagram Flow or Swimlane.