UML/SysML Activity Node Information

Activity Diagram:	The Activity Diagram is similar to the classic flow chart. It describes a workflow or algorithm by decomposing the flow of execution into a set of actions and sub activities joined by transitions and various connectors. These actions and sub activities are called activity nodes. An activity diagram can be a simple linear sequence of actions or it can be a complex series of parallel actions with conditional branching and concurrency. The example shows the sequence of actions associated with the alignment of a gun to the Line of Sight (LoS).
Sequence Diagram:	In the SE workflow, an action is the equivalent of an operation. Using the SE-Toolkit feature Create New Scenario from Activity Diagram (Link Wizard), the sequence of actions is translated into a respective sequence of (auto realized) operations in a Sequence Diagram.
Statechart Diagram:	In the Statechart Diagram, the sequence of actions / operations typically is associated with a state transition. Notation: Event[Condition] / Action(s). In the example the triggering event is the default entry into the state GunAligned. NOTE: Arguments were added to the auto realized operations (input parameter, output parameter). This – optional - extension has to be performed in the browser. The sequence diagram will be automatically updated (ref. next page).

Activity Node with ActorPins Information

Activity Diagram:	Harmony for Systems Engineering uses a SysML activity pin stereotyped <<ActorPin>> to visualize the interaction of an action/operation with the environment. The name of the pin is the name of the associated actor, the arrow in the pin shows the direction of the link (input and/or output) In the example the action calculateLosCmd was added. This action will be initiated by the gunner. Only the actThe triggering event will be defined in the Sequence Diagram (below).
Sequence Diagram:	The example shows the sequence diagram generated by means of the SE-Toolkit feature Create New Scenario from Activity Diagram (Link Wizard). Based on the information from the pin, the wizard creates a generic message from the gunner. This message needs to be named (e.g. reqCalculateLosCmd) and auto realized. NOTE: It is highly recommended to standardize the naming of actor messages.
Statechart Diagram:	Activity nodes with input ActorPin(s) are translated into Wait States named WaitFor… NOTE: It is highly recommended to standardize the naming of Wait States. Typically, the triggering event initiates a state transition. Notation: Triggering Event / Operation(s). In the example, the line-of-sight calculation will be based on the position/rate information of the gunner’s handle. Thus, the `triggering event (reqCalculateLos) has arguments (HandlePos, HandleRate). The operation calculateLosCmd refers to them via the “params” notation of the Rhapsody action language. The respective extensions of the message and associated operation need to be done in the browser. The previously generated sequence diagram will be automatically updated accordingly (ref next page).

Message Action Information

Activity Diagram:

The Systems Engineering process guidance uses UML/SysML activity nodes stereotyped << MessageAction>> to describe in an Activity Diagram incoming messages that trigger a system mode switch, provide requested data or send messages. If the message is related to an actor, the sender / recipient of the message needs to be denoted by a respective ActorPin. NOTE: Although the name of a message action is purely documental, it is highly recommended to standardize the naming. In the example, the control of the alignment of the gun to the LOS is initiated through the gunner by engaging the palms.

Sequence Diagram:

The example shows the Sequence Diagram created from the Activity Diagram above by means of the SE-Toolkit feature Create New Scenario from Activity Diagram (Link Wizard). NOTE: Message Actions are “translated” only w.r.t. the received/sent messages denoted by respective ActorPins.