CORRECT InitialNode explicit fork

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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
InitialNode
JoinNode
ControlFlow
Keywords
Slide kind
UML Activity Diagram
The use of a ForkNode after an InitialNode is one way to address the initialisation problem illustrated in the previous slide:
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We see in the next slide another option for handling this correctly, namely using two InitialNodes.

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OPTION double InitialNode
Notes
Snippets (quotes/extracts)
  [UML-2.5.1] An InitialNode shall not have any incoming ActivityEdges, which means the InitialNodes owned by an Activity will always be enabled when the Activity begins execution and a single control token is placed on each such InitialNode when Activity execution sta
  [UML-2.5.1] The outgoing ActivityEdges of an InitialNode must all be ControlFlows. The control token placed on an InitialNode is offered concurrently on all outgoing ControlFlows.
  [UML-2.5.1] As an ActivityNode may be the source for multiple ActivityEdges, the same token can be offered to multiple targets.
  [UML-2.5.1] 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 ...).
  [UML-2.5.1] 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.
  [UML-2.5.1] 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.
  [UML-2.5.1] Tokens offered to a ForkNode are offered to all outgoing ActivityEdges of the node. If at least one of these offers is accepted, the offered tokens are removed from their original source and the acceptor receives a copy of the tokens.
Related slides (includes other tutorials)
Related slides (backlinks, includes other tutorials)
OPTION double InitialNode
ExecutableNode has implicit fork
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