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pre and post conditions in OCL metamodel [message #1748556]

Thu, 24 November 2016 10:49

meriem lahr

Messages: 31
Registered: March 2013

Member

Hi all,

I would like to express transformation constraints (preconditions, postconditions and invariants) that conform to the OCL metamodel.

The OCL metamodel contains a definition of OCL expressions. But how to indicate, for an OCL expression, if it is a postcondition, precondition or invariant?

Thank you very much

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Re: pre and post conditions in OCL metamodel [message #1748557 is a reply to message #1748556]

Thu, 24 November 2016 11:06

Ed Willink

Messages: 7655
Registered: July 2009

Senior Member

Hi

Complete OCL supports definition of an OCL document that complements an existing meta-model. It provides for the definition of pre/post-conditions on operations.

If your transformation language provides a metamodel, as QVT does, then since a Transformation is-a Class you could add invariants to the Transformation. However a Rule is not an Operation so you cannot add pre/post-conditions to Rules.

However you write vaguely that you want transformation pre/post-conditions. What are they? A declarative model transformation has only two states, the input and the output, so do you really just mean a set of invariants on the input and a set of invariants on the output? These can be specified by Complete OCL using your input/output meta-models totally independent of your unspecified transformation technology.

If you are looking towards new technology, I can see a case whereby a transformation language's input/output model declarations could be extended to support invariants that could optionally be checked at run-time and could be exploited by the execution.

Regards

Ed Willink

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Re: pre and post conditions in OCL metamodel [message #1748559 is a reply to message #1748557]

Thu, 24 November 2016 11:52

meriem lahr

Messages: 31
Registered: March 2013

Member

Hi Ed,

Thanks for your answer and sorry, my question was not clear. The transformation constraints are as follow :

constraints on a model to be transformed
constraints on a model to be a valid result of the transformation (these constraints are independent of the source model)
constraints on the evolution between source and target models

My OCL constraints specification doesn't depend on a language or an execution (but they are specific to input/output metamodel). My goal is to be able to express them conforming to a metamodel in order provide them as input of a higher order transformation.

Regards

Meriem

[Updated on: Thu, 24 November 2016 16:56]

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Re: pre and post conditions in OCL metamodel [message #1748571 is a reply to message #1748559]

Thu, 24 November 2016 15:14

Ed Willink

Messages: 7655
Registered: July 2009

Senior Member

Hi

I am no clearer what you are really trying to do that I did not answer earlier.

Always a good idea to give an example, rather than expect me to successfully guess at what you mean.

Regards

Ed Willink

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