ArchiMate Metamodel
The assignment relationship links active structure elements with units of behavior that are performed by them, business actors with business roles that are fulfilled by them, locations with structure elements, and artifacts with nodes. It can, for example, relate an internal active structure element with an internal behavior element, an interface with a service, or a location with an active or passive structure element. The full set of permitted relationships is listed in Appendix B.
Note that although this notation is not directional, the assignment relationship does have a direction at the metamodel level. In the ArchiMate framework described in Section 3.4, it always points from a location to an active structure element, from active structure to behavior, and from active structure to passive structure. This directionality may optionally be expressed in the notation by omitting the black dot at the source end of the relationship, only showing it at the destination end.
As with all structural relationships, an assignment relationship can also be expressed by nesting the model elements. The direction mentioned above is also the direction of nesting; for example, a business actor can be drawn inside the location where it resides, a business role inside the business actor performing that role, an application function inside an application component executing that function, or an artifact inside a node that stores it.
The usual interpretation of an assignment relationship is that whole or part of the source element is assigned the whole of the target element. This means that if, for example, two active structure elements are assigned to the same behavior element, either of them can perform the complete behavior. If both active structure elements are needed to perform the behavior, the grouping element or a junction (see Section 5.4.3) can be used, and if the combination of these elements has a more substantive and independent character, a collaboration would be the right way to express this.
