[news.eclipse.tools.emf] Re: OCL checker for EMF models in transformatio

[Damien Thivolle <damien.thivolle@xxxxxxxx>]

Ed Merks a écrit :
> Damien,
>
> Comments below.
>
> Damien Thivolle wrote:
> > Ed Merks a écrit :
> > > Damien,
> > >
> > > Comments below.
> >
> > Thanks!
> > > Damien Thivolle wrote:
> > > > Hello,
> > > >
> > > > I'm relatively new to Eclipse and the modeling technology. I want to 
> > > > write a transformation from a meta-model MMa to a meta-model MMb 
> > > > using ATL. The problem is that the transformation will only concern 
> > > > a subset of MMa.
> > > There's a newsgroup for ATL.  I've included it on the "to" list of 
> > > the reply.
> >
> > Thank you but I don't have any problems with ATL and I'm in close 
> > contact with the ATLAS team anyway.
> I guess the introduction of wanting to write an ATL transformation threw 
> me...
> > > > I've been hinted to write a checker in OCL that would just tell me 
> > > > whether a model Ma (conforming to MMa) is included in the subset I'm 
> > > > interested in.
> There's also an OCL-specific newsgroup... The EMF extended validation 
> framework includes support for writing constraints with OCL 
> (org.eclipse.emf.validation.ocl).
> > > > In the end, if the checker answers true when asked if the input 
> > > > model is correct, the transformation would take place, if not an 
> > > > error message would be yielded.
> > > >
> > > > I've been looking for some clues as to where to start and I was 
> > > > expecting to find something suitable for a newbie like me. Like, I 
> > > > define a file with a set of OCL constraints, right click on my model 
> > > > and choose "Validate constraints from file...". But I guess it's not 
> > > > gonna be that easy.
> > > >
> > > > More generally, I'm having a hard time finding my way around 
> > > > Eclipse, EMF and such... I've been reading all the material I could 
> > > > find about using OCL to check constraints on EMF models, and it's 
> > > > like Chinese to me.
> > > Note really.  If it were Chinese it would use an alphabet you'd not 
> > > recognize.  :-P
> >
> > Yeah, sorry about my whining :) It's just that usually with Eclipse, 
> > the documentation gives you a lot of examples as starting points. But 
> > too often, there aren't enough explanations to make you really 
> > understand what you're doing (see the doc for the OCL environment 
> > class which takes  12 template parameters...).
> Let me whine a bit myself.  Have you had a look at some of the 
> specifications written out there?  How are users supposed to understand 
> things like that?

You're very right about that...

> > > > For example, I've seen a lot of EMF models with annotations named 
> > > > "OCL" and having several entries, but I can't really find anything 
> > > > that would explain me what to do with those.
> > > Did you look at the Eclipse help?
> > > > I'm just saying is that I find it hard to understand this technology 
> > > > and I'm wondering if it's normal or if this is where my 
> > > > comprehension reaches its limits.
> > > There's an awful lot of technology to learn all at once for sure.  
> > > And the documentation is sometimes a little lacking or hard to find...
> >
> > My models are in files with a .sam extension and I want to write an 
> > ocl file with constraints for my models. The SAM meta-model is written 
> > in Ecore.
> Hmmm.  I know the validation framework supports writing contains for the 
> SAM.ecore model that would apply to instances stored in *.sam files.  I 
> know Christian has written some nice help information for how to get 
> started with live validation...

Yes, I've read all this, and it's really awesome. But I'm not really 
sure if I need live validation, maybe later, I need to think some more ;)

> > So I was thinking I could implement a contextual menu action that 
> > would only be available for files with a .sam extension. When handling 
> > that action, I would open that model file in JAVA as you explained in 
> > one of your previous messages on this newsgroup 
> > (<fmnq3n$qrm$1@xxxxxxxxxxxxxxxxx>). 
> The basic generated editor already includes support for validating basic 
> constraints. 
> http://help.eclipse.org/help33/index.jsp?topic=/org.eclipse.emf.doc//references/overview/EMF.Validation.html

I know that, but I can't modify the SAM meta-model, I have to build my 
checker around what already exists.

> I'm not sure if you ever tracked these references down:
>
>     http://help.eclipse.org/help33/nav/25
>     http://help.eclipse.org/help33/nav/34
>
>
> > Then I would ask the user to choose an ocl file and would use the OCL 
> > Eclipse project to open that OCL file, parse it and verify the 
> > constraints on my SAM model. Does that sound alright or is there a 
> > better way to do it?
> I think Christian has nice frameworks in place for all of this and that 
> he's documented them well.  I guess it's a little hard to find though, 
> but it is in the help system under fairly easy-to-find headings.

I've found all the documentation, read it and what I explained above is 
how I think I should proceed after having processed all I read. I just 
wanted to know if this seems a correct way to check a set of OCL 
constraints on SAM models given the fact that I can't modify the SAM 
meta-model.

Best regards,

--
Damien THIVOLLE                   |     INRIA Rhone-Alpes / VASY
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