UML behavioral state diagram: entry and exit point ownership implications for orthogonal states

Question

In UML (let's take specification 2.4.1), when considering orthogonal composite states, entry and exit points belong either to the (enclosing) composite state or to the region the entry / exit point is drawn in. So which is it?

I cannot find this explicitly in the specification, but this is what the spec says about the subject (taken from paragraph 15.3.8 of the superstructure specification): "An entry point pseudostate is an entry point of a state machine or composite state. In each region of the state machine or composite state it has at most a single transition to a vertex within the same region."

From this I infer that entry points belong to the region they are applied to. If so, how do I model entry / exit actions for the enclosing state? Do I have to repeat a 'state-wide entry action' on every entry point I use? This seems cumbersome and redundant when using many regions. Or do I have to create a 'greater' state that has its own entry / exit points (or 'entry / ...' and 'exit / ...' lines), which in turn encloses the composite state which contains the regions? This seems rather complex. Can somebody clarify this for me with a visual example?

Answer 1

If you want to model actions that are executed before entering the orthogonal regions, yes: you need to create an enclosing state (See Fig. 15.35 "Orthogonal state with regions" in 2.4.1 superstructure).

From clause 15.3.11:

A composite state either contains one region or is decomposed into two or more orthogonal regions. Each region has a set of mutually exclusive disjoint subvertices and a set of transitions. A given state may only be decomposed in one of these two ways.

On the other side, if all you need are entry/exit pseudostates, you can avoid that additional complexity. See the paragraph about Composite state, its Description and Semantic variation point (default entry rule) in clause 15.3.11.