Transactional Petri nets (TPNets) are a new class of high-level zero-safe nets (ZSNs), defined as a semantic framework for UML2 activity diagrams. Indeed, they capture the behaviour associated with non-local actions triggering, cancellation patterns and the advanced synchronisation that result. While, reactivity is guaranteed due to the real time massive cancellation semantics, based on the definition of new dynamic enabling rules and the definition of priority among executions, global synchronisation in turn is assured as a result of non-locality principle; an outcome of atomic stable transactions use. The operational semantics of TPNets is defined within rewriting logic-based framework.