Activity Partition   An activity partition is a type of activity group that specifies that a number of elements in an activity have something in common. Partitions may be oriented horizontally or vertically, and except in the case that a partition is a dimension can contain other partitions down to any level of nesting. Partitions have no effect on the execution of an activity or the nodes and edges contained within it.

Explanation

An activity partition is a way of viewing or grouping the various parts of an activity. The grouping can be based on any characteristic specified by the modeler but most typically define things such as worker responsibility or location in a business model, or the classifier or instance that carries out the action in a software system. This may be a class, component, node or any other type of classifier or instance. The partitions can be orientated horizontally or vertically and can contain any number of other partitions (except in the case of a dimension). A dimension is the highest-level partition and cannot be contained in other partitions. The term swim lane has been used to describe partitions that are siblings of the same dimension, because of their visual similarity to the lanes in a swimming pool. This term can cause some confusion because it implies that there are flows going on in the various lanes at the same time. While this could be possible in the case of concurrent flows it is more typical that one or more actions are carried out in one lane and then control is passed onto actions in other lanes. Vertical and horizontal partition can also be used together to show different characteristics such as who is responsible for an action and where the action occurs.

Important Points

		A partition, which is a dimension, cannot be contained by another partition.		When a partition has the 'isDimension' attribute set to true it signifies that the partition is the highest-level partition and cannot be contained by another partition.
		A node or flow can only be in one (and only one) partition within any given dimension.		A node or flow cannot be in more than one partition within any given dimension implying that the contents of the partitions within a dimension are disjoint sets of nodes and edges (flows).

Related Entries

Action  Owned Element An action is related to an activity partition in that an action is owned by an activity partition. The activity partition groups related actions together.

Activity Partition  Owned Element An activity partition is related to another activity partition in that an activity partition can itself contain another activity partition allowing nested hierarchies of activity partitions to be created.