FUML11 — Error in check for enable nodes

Specification: Semantics of a Foundational Subset for Executable UML Models (fUML) (formal/2011-02-01)

Subclauses: 8.5.2.2.5 ActivityNodeActivationGroup, 8.5.3.2.4 StructuredActivityNodeActivation

The ActivityNodeActivationGroup::run operation checks which of the node activations in a given set are initially enabled. It does this using the checkIncomingEdges operation to check whether a node has incoming edges with a source within the given set of node activations. The checkIncomingEdges operation in turn uses the ActivityNodeActivation::sourceFor operation to check if an activity node activation is the source for a given activity edge instance. By default, this is true if the activity node activation is the source of the activity edge instance. The sourceFor operation is overridden in ActionActivation to account for the fact that outgoing control flows are attached to an ActionActivation via an anonymous fork node but, otherwise, the default behavior is used.

With the current specification for sourceFor, if a node activation has an incoming edge instance from within a structured activity node activation, rather than from the structured activity node itself, the structured activity node activation will not be considered the source for the edge instance, and the current specification for checkIncomingEdges does not look for sources inside structured activity nodes. This means that, if an activity node only has incoming edges with sources nested within a structured activity node, it may be spuriously considered to be enabled when it really has predecessor dependencies.

agreed