Learn about Webel IT's new SysMLv2/MBSE Workshop Seminar course!

OR with DecisionNode and MergeNode

Gallery
Tutorial
TRAIL: Webel's ultimate guide to Systems Modeling Language (v1) with MagicDraw/Cameo
Section
01:04: UML Behavior: Activities quick start
Topic level
ESSENTIAL
UML keywords
Activity
Activity Diagram
MergeNode
DecisionNode
Slide kind
UML Activity Diagram
This shows the basics of a DecisionNode combined with a MergeNode and some UML background info:
Click on the image to view it full size

There is a mini-video of DecisionNode and MergeNode used together to create a simple ControlFlow loop at:

SysMLv1: A basic ControlFlow and DecisionNode loop with implied variable popup dialog [with mini video]

An there is a mini-video of DecisionNode and MergeNode used together with ControlFlow and ObjectFlow to create a loop at:

SysMLv1: A basic ControlFlow, ObjectFlow, and DecisionNode loop driven by fUML ReadLine CLI String input [with mini video]
For more on using DecisionNode in Magic Model Analyst® (Cameo Simulation Toolkit®) visit:
Visit also: TIP/GOTCHA: SysMLv1/fUML: Cameo Simulation Toolkit: If you have a ControlFlow loop with a DecisionNode test you MUST have a MergeNode for the continuation path ControlFlow (typically entered also from an InitialNode or other loop starting point).
Visit also: TIP/GOTCHA: SysMLv1/UML: Cameo Simulation Toolkit: If you use a «decisionInputFlow» to a DecisionNode you MUST also have a ControlFlow to the DecisionNode; if you don't use an explicit «decisionInputFlow» you don't need the "extra" ControlFlow
Visit also: TIP: SysMLv1/UML: Cameo Simulation Toolkit: HOWTO convert an fUML ReadLine CLI String to a Boolean for cleaner DecisionNode tests against a LiteralBoolean [true] guard.
Up next
AND with ForkNode and JoinNode
Notes
Snippets (quotes/extracts)
  [UML-2.5.1] A DecisionNode is a ControlNode that chooses between outgoing ActivityEdges for the routing of tokens.
  [UML-2.5.1] 15.3.3.6 Decision Nodes - A DecisionNode is a ControlNode that chooses between outgoing flows.
  [UML-2.5.1] A DecisionNode shall have at least one and at most two incoming ActivityEdges, and at least one outgoing ActivityEdge.
  [UML-2.5.1] If it has two incoming edges, then one shall be identified as the decisionInputFlow, the other being called the primary incoming edge. If the DecisionNode has only one incoming edge, then it is the primary incoming edge.
  [UML-2.5.1] A DecisionNode accepts tokens on its primary incoming edge and offers them to all its outgoing edges. However, each token offered on the primary incoming edge shall traverse at most one outgoing edge. Tokens are not duplicated.
  [UML-2.5.1] DecisionNode::edges The ActivityEdges incoming to and outgoing from a DecisionNode, other than the decisionInputFlow (if any), must be either all ObjectFlows or all ControlFlows.
  [UML-2.5.1] DecisionNode::incoming_outgoing_edges A DecisionNode has one or two incoming ActivityEdges and at least one outgoing ActivityEdge.
  [UML-2.5.1] a predefined guard “else” (represented as an Expression with “else” as its operator and no operands) may be used for at most one outgoing edge. This guard evaluates to true only if the token is not accepted by any other outgoing edge from the DecisionNode
  [UML-2.5.1] A MergeNode is a control node that brings together multiple flows without synchronization.
  [UML-2.5.1] A MergeNode shall have exactly one outgoing ActivityEdge but may have multiple incoming ActivityEdges.
  [UML-2.5.1] If the outgoing edge of a MergeNode is a ControlFlow, then all incoming edges must be ControlFlows, and, if the outgoing edge is an ObjectFlow, then all incoming edges must be ObjectFlows.
  [UML-2.5.1] All tokens offered on the incoming edges of a MergeNode are offered to the outgoing edge. There is no synchronization of flows or joining of tokens.
Related slides (includes other tutorials)
Related slides (backlinks, includes other tutorials)
Visit also
Visit also (backlinks)
SysMLv1: TIP: SysMLv1: Cameo: JoinNode and MergeNode distinguishing notations option
SysMLv1: Cameo Simulation Toolkit: Comparison of a Fork then a Merge with a Fork then a Join [with mini video]
TRAIL: SysMLv1/UML: Cameo Simulation Toolkit® (Magic Model Analyst®): Some basics for beginners and some more advanced cases [with mini videos]
TIP: SysMLv1/UML: Cameo Simulation Toolkit: HOWTO convert an fUML ReadLine CLI String to a Boolean for cleaner DecisionNode tests against a LiteralBoolean [true] guard.
TIP/GOTCHA: SysMLv1/fUML: Cameo Simulation Toolkit: If you have a ControlFlow loop with a DecisionNode test you MUST have a MergeNode for the continuation path ControlFlow (typically entered also from an InitialNode or other loop starting point).
TIP/GOTCHA: SysMLv1/UML: Cameo Simulation Toolkit: If you use a «decisionInputFlow» to a DecisionNode you MUST also have a ControlFlow to the DecisionNode; if you don't use an explicit «decisionInputFlow» you don't need the "extra" ControlFlow