CAM-13207 DMN execution context

[jangalinski]

In order to allow hooking into the den decision evaluation, the engine should not create the context via new. Instead, it should use a factory which can be configured via the engineConfiguration.

See https://jira.camunda.com/browse/CAM-13207

[jangalinski]

I didn't provide tests so far ... but the default behavior did not change, so the existing tests will prove everything still works. Please get in touch to discuss which tests I should provide (and how I can set up my local build ... currently, I cannot run tests).

[jangalinski]

Note: I used separate smaller commits instead of squashing them together, because while working on this, I fixed javadoc typos and added override annotations ... those commits should end up in master independently, imho.

[mboskamp]

Hey @jangalinski, as mentioned in the CAM ticket. We will get back to you as soon as possible. Currently, the 7.15.0 release is taking up all the resources.

Cheers,
Miklas

[tmetzke]

Hey @jangalinski,

as mentioned in CAM-13207, we will close without a merge here. While the changes are valid and reasonable itself, you should be able to achieve the desired behavior already with the DmnDecisionEvaluationListener.

Let us know if we missed anything so we should reconsider.

Best,
Tobias

[jangalinski]

No, I can't use DmnDecisionEvaluationListeners. That was the whole point of this PR. listeners are only implemented for decisionTables. In case of expressions and literal expressions, I do not have listeners. That's why I introduced this abstraction layer, so I can overwrite (aka fix) this missing behavior.

[jangalinski]

Concrete use case: in a DRD that uses expressions and tables, I want to get the intermediate results of each sub-execution. Possible for tables, impossible for expressions.
If I do not get it right, could you show me a working example?

[tmetzke]

Hey Jan,

thanks for that feedback.

I just did a quick debug with a decision that consists of a literal expression and I can see that the registered DmnDecisionEvaluationListeners are informed about the decision result containing the literal expression information in the DefaultDmnDecisionContext. The DmnDecisionEvaluationListeners are invoked after the evaluation of a decision, no matter what is inside that decision (literal expression, decision table).

This might however not exactly cover your use case. Therefore, would you mind detailing what you would want to change in DefaultDmnDecisionContext so it provides the behavior you expect? It might also help us if you provide a specific example DMN that does not work as you expect. Please describe along that example what already works as expected and what doesn't. This will help us to better understand the specific use case.

Thanks and best,
Tobias