It is quite apparent that responsibilities for many of the activities listed on our diagram do not belong in the Stoppage System interface. For example, the responsibility for activity Evaluate Reorder Purchase Points most likely belongs to an Inventory interface. The responsibility for activity Evaluate End Product Demand belongs to an interface that addresses Sales. Note that activity diagrams are not the best way to document responsibility. It is possible, but cumbersome.
Interaction diagrams are a much nicer way to depict the assignment of responsibility for activities.
With activity diagrams, we take a first pass at responsibility assignment. This will lead us to the next step, which is to explore interface inventory to find operations that will satisfy the activity requirement. Look for Reuse Opportunities Activity diagrams are an excellent tool to help find reusable assets. Each activity focuses on an action against some type, or domain concept, much the same way public operations are defined. Each activity description contains information about requirements, including business rules and algorithms, where applicable.