OCL from dynamic contraints converted into OCL Derived Properties

Question

Dear Forum

I am a dynamic contraint that applies on DC Worksheet. As it is executed only on demand I would like to transform it as a OCL Deriving Properties...but it seems not to work in the same manner...especially in my case I have an error message concerning "inv:" misplaced construct.

So how to do ?

medini_1004872874 · Answer

Thanks Eckhardt for your clarification. I've got now the philosophy....Even if I did not succeed yet to implement with your hint..but I am in the right way I think ;o)

medini_1023909254 · Answer

Hi Florent,

yes, you have to do some additional adjustments and can not directly copy&paste the constraint into a profile property.

The 'inv:' in an constraint indicates that the following ocl expression is considered to be an invariant and must evaluate to true - if not, the error message will be displayed.

In an profile property you give on the other side just an expression which will result in a value - so in order to achieve the same behaviour, you need to surround the expression with an if-statement. Moreover, you may have to check, what to do with the potential message arguments in the constraint. Here is a small demo example based on constraint #4 from medini:

--constraint #4: Each ASILc&D goal shall be traced to an FTA

inv:
let
MessageArg1:String= self.identifier
in
if (self.asil='C' or self.asil='D') then
-- any FTA model, event (node), gate, connection traced?
not (self.mediniGetTracedElements(FTA::FTAElement)->isEmpty() and self.mediniGetTracedElements(FTA::EventNode)->isEmpty())
else
true
endif

An appropriate profile property for safety goal could be based on this as

if
if (self.asil='C' or self.asil='D') then
-- any FTA model, event (node), gate, connection traced?
not (self.mediniGetTracedElements(FTA::FTAElement)->isEmpty() and self.mediniGetTracedElements(FTA::EventNode)->isEmpty())
else
true
endif
then
'[o]'
else
'[!]'
endif

You can see how the original constraint is surrounded by an if-statement. The output would look as follows:

Best regards,

Eckhardt