Details
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New Feature
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Status: Resolved
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Major
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Resolution: Fixed
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2.0
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None
Description
One of the targets for the Commons SCXM 2.0 roadmap milestone 1 is to redefine SCXMLSemantics to align with the SCXML Algorithm for SCXML Interpretation, see: http://www.w3.org/TR/scxml/#AlgorithmforSCXMLInterpretation
The current SCXMLSemantics interface and its implementation is so much different from the algorithm in the specification that 'molding' it into what the algorithm now expects is too cumbersome.
The current SCXMLSemantics and its implementation will therefore be completely replaced with a new one, closely corresponding to the semantics of the SCXML Algorithm in the specification.
The algorithm described in the specification leaves plenty of room for optimization and choice of techniques.
For a first cut implementation though I intend to simply follow the described algorithm as close as possible, also to make sure not to deviate from the specification already too early 
After the new implementation has been tested and validated to be conforming the expected behavior, or even later than that, the implementation surely can be refined and optimized further.
The changes needed for this task are closely related to those described in SCXML-197: Better separation of concern between SCXMLExecutor and SCInstance and introducing a new SCXMLExecutionContext.
Although through SCXML-197 already many improvements are realized, to be able to implement the new SCXMLSemantics requires additional (major) changes, which functionally should be regarded part of SCXML-197, but cannot be committed separately as the changes are too closely related.
I'll therefore update SCXML-197 describing those functional changes regarding the better separation of concerns, although they will be committed against this issue.
An important note is that with the re-implementation of the SCXMLSemantics, the static SCXMLHelper class, as well as the (Transition) Path helper class functionalities will be completely 'absorbed' into the model and the new algorithm implementation. These classes therefore no longer are used and needed and will be removed.
Furthermore, the Step class now only is used from within the SCXMLSemantics implementation and therefore moved to the semantics package.
With these changes in SCXML-196 and SCXML-197, the goals for Milestone 1 on the roadmap to SCXML 2.0 have been completely met and I'll create a milestone 1 svn tag for it shortly.