What this function does: AIB3_EVALUATE_ODS_ASSIGN in PS/IM?

Question

Dear all,
I'm investigating for the possible cause of data lost in transit in PS/IM area. The suspect currently is an update rule involving a function AIB3_EVALUATE_ODS_ASSIGN, as based on its E_SUBRC output value a record is skipped or not. Though I'm working with Z-objects now, this turns to be a part of Business Content as well.
Does anyone has an idea what is the logic of that function? SAP doesn't provide any documentation on that, so the only option I have at the moment is to play with that blackbox...
Cheers!
/RB

Answer 1

I'm not worried about race conditions, as evaluation of the expression takes place as the last thing before the new execution is started. It must either be done just before the SequenceCall, or as the first thing in the Setup group of the subsequence.
It's fragile to modify the expression at runtime to mimic a different context (by replacing stuff like "Locals." with "RunState.Caller.Locals." for instance, if they were in the same callstack), since such string replacement could never be exhaustive. What about "Step."? What about constructs like ("L" & "ocals.")? I could never identify them all.
I could split the expression up in two, like this (evaluated in the subsequence):
Evaluate("Locals." + Locals.TargetName) = Evaluate("RunState.Caller.Locals.SourceName")
The above works if Locals.SourceName was in the caller context, but my problem is a bit more complex than that; I need the right hand side to evaluate any expression string, and I need to supply a context to do it within. It's too fragile to string-replace "Locals." with "RunState.Caller.Locals." etc., as the expression might contain "Parameters.", "FileGlobals.", or much more complex access patterns from the caller context.
One way would be to make a new expression object and use Expression.Evaluate(context,evaloptions) on that in the subsequence, with context passed from the caller, but how do I make and pass an expression object to the sequence in which to set the TargetName local variable? It has something to do with Engine.NewExpression, but where do I store this expression object in the caller? And how do I set its Text property to "Locals.SourceName" (in this particular example, but remember it could be any expression)? And finally how do I pass this expression object to the subsequence via a parameter (what type should the parameter be)?
Cheers,
Steen
CLA, CTA, CLED & LabVIEW Champion