Icon class icon_class fas fa-quote-left icon_class_computed fas fa-quote-left Related content Source Unified Modeling Language 2.5.1 Copyright information About Object Management Group copyright in text extracts quoted from OMG specifications for educational purposes Snippet kind INFO UML keywords Behavior Activity Activity Diagram ExecutableNode ActivityNode execution Previous snippet Full quote An ExecutableNode is an ActivityNode that carries out a substantive behavioral step of the Activity that contains it. Next snippet Related snippets A ControlFlow is an ActivityEdge traversed by control tokens or object tokens of control type, which are use to control the execution of ExecutableNodes no_executable_nodes ObjectFlows may not have ExecutableNodes at either end. An ExecutableNode is a kind of ActivityNode that may be executed as a step in the overall desired behavior of the containing Activity. All concrete kinds of ExecutableNodes are Actions ... Related snippets (backlinks) An ExecutableNode may also consume and produce data, but it must do so through related ObjectNodes (Actions use Pins for this purpose ... An ExecutableNode shall not execute until all incoming ControlFlows (if any) are offering tokens. That is, there is an implicit join on the incoming Control Flows. Specific kinds of ExecutableNodes may have additional prerequisites ... Before an ExecutableNode begins executing, it accepts all tokens offered on incoming ControlFlows. If multiple tokens are being offered on a ControlFlow, they are all consumed. The effect of object tokens accepted from ControlFlows is not specified (see isControlType for ObjectNodes ...), but the semantics above applies if the effect is to execute the ExecutableNode. While the ExecutableNode is executing, it is considered to hold a single control [token] indicating it is execution [executing]. In some cases, multiple concurrent executions of an ExecutableNode may be ongoing at one time (see the semantics of isLocallyReentrant=true for Actions ... ). In this case, the ExecutableNode holds one control token for each concurrent execution. When an ExecutableNode completes an execution, the control token representing that execution is removed from the ExecutableNode and control tokens are offered on all outgoing ControlFlows of the ExecutableNode. That is, there is an implicit fork ... ExecutableNodes actually carry out the desired behavior of an Activity. If an ExecutableNode has incoming ControlFlows, then there must be tokens offered on all these flows that it accepts before beginning execution. As an ActivityNode may be the source for multiple ActivityEdges, the same token can be offered to multiple targets. However, the same token can only be accepted at one target at a time (unless it is copied, whereupon it is not the same token, see ForkNodes ... and ExecutableNodes ...). If a token is offered to multiple ActivityNodes at the same time, it shall be accepted by at most one of them, but exactly which one is not completely determined by the Activity flow semantics. This means that an Activity model in which non-determinacy occurs may be subject to timing issues and race conditions. It is the responsibility of the modeler to avoid such conditions in the construction of the Activity model, if they are not desired. Visit also Visit also (backlinks) Flags
