When modeling concurrent or parallel systems, we must be aware that basic activities of each system may be constituted by smaller activities, i.e. transitions may be conceptually refined into transactions. Nevertheless, the Unified Modeling Language seems to lack compositional constructs for defining atomic actions/activities/operations. We discuss proper extensions for UML behavioral diagrams that are able to cope with the concept of transaction. Transactions are formally defined through a special morphism between automata in a semantic domain called Nonsequential Automata.
['Júlio Henrique Araújo Pereira Machado', 'Paulo Blauth Menezes']
Composing transitions into transactions in UML diagrams