Issue 17291: ForkNodeActivation does not clear its tokens on termination (fuml-rtf)
Source: Model Driven Solutions (Mr. Ed Seidewitz, ed-s(at)modeldriven.com)
Nature: Uncategorized Issue
Severity: 
Summary: Specification: Semantics of a Foundational Subset for Executable UML Models (fUML) (formal/2011-02-01)

Subclause: 8.5.2.2.11 ForkNodeActivation

 

Unlike other control nodes, a fork node actually holds forked tokens pending their acceptance by downstream nodes. Therefore, when a ForkNodeActivation terminates, it needs to clear its held tokens, similarly to an ObjectNodeActivation. It currently does not do this, which means, if it is fired repeatedly in a loop node, and not all of its held tokens are accepted on previous iterations, it will be spuriously holding extra tokens on subsequent iterations.

 

Adding the following overriding method to ForkNodeActivation is sufficient, because ActivityNodeActivation::clearTokens() repeatedly withdraws held tokens until none are left, which will work even for multiply forked tokens.

 

                public void terminate() {

                                // Remove any offered tokens and terminate.

 

                                this.clearTokens();

                                super.terminate();

                } // terminate

 

Resolution: agreed
Revised Text: In Figure 8.27, add the (overriding) operation “terminate()” to the class ForkNodeActivation, and add the following specification for it in Subclause 8.5.2.2.11:
terminate()
// Remove any offered tokens and terminate.

this.clearTokens();
super.terminate();

Actions taken:
April 6, 2012: received issue
January 7, 2013: closed issue
Discussion: 

End of Annotations:=====

m: Ed Seidewitz <ed-s@modeldriven.com>
To: "issue@omg.org" <issue@omg.org>
Date: Fri, 6 Apr 2012 00:32:38 -0400
Subject: ForkNodeActivation does not clear its tokens on termination
Thread-Topic: ForkNodeActivation does not clear its tokens on termination
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Specification: Semantics of a Foundational Subset for Executable UML Models (fUML) (formal/2011-02-01)

Subclause: 8.5.2.2.11 ForkNodeActivation

 

Unlike other control nodes, a fork node actually holds forked tokens pending their acceptance by downstream nodes. Therefore, when a ForkNodeActivation terminates, it needs to clear its held tokens, similarly to an ObjectNodeActivation. It currently does not do this, which means, if it is fired repeatedly in a loop node, and not all of its held tokens are accepted on previous iterations, it will be spuriously holding extra tokens on subsequent iterations.

 

Adding the following overriding method to ForkNodeActivation is sufficient, because ActivityNodeActivation::clearTokens() repeatedly withdraws held tokens until none are left, which will work even for multiply forked tokens.

 

                public void terminate() {

                                // Remove any offered tokens and terminate.

 

                                this.clearTokens();

                                super.terminate();

                } // terminate