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3 or 4 layers [message #757795]

Mon, 21 November 2011 17:39

Elhamlaoui Mahmoud

Messages: 268
Registered: March 2010

Senior Member

Hi,

I have an understanding problem: Sad

OMG talks about 4 layers and i could find just 3 while working with EMF, if so, what is the instance class diagram in EMF?

Thanks alot

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Re: 3 or 4 layers [message #757990 is a reply to message #757795]

Mon, 21 November 2011 17:50

Ed Merks

Messages: 33140
Registered: July 2009

Senior Member

Which layer do you think is missing?

On 21/11/2011 6:40 PM, elhamlaoui wrote:
> Hi,
>
> I have an understanding problem: :(
> OMG talks about 4 layers and i could find just 3 while working with
> EMF, if so, what is the instance class diagram in EMF?
>
> Thanks alot

Ed Merks
Professional Support: https://www.macromodeling.com/

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Re: 3 or 4 layers [message #758051 is a reply to message #757990]

Mon, 21 November 2011 20:08

Elhamlaoui Mahmoud

Messages: 268
Registered: March 2010

Senior Member

Hi Ed,

I was hoping that i you were the one who answer to this, im lucky Smile

It deponds it could be M1 or M0(according to OMG layer), what I try to achieve is projection of the OMG layer on the EMF.IN the EMF i could got just model->MM->MMM(Ecore), if we take an example of a class diagram in UML:

Instance class diagram-> class diagram-> MMUML->MOF

What it would be the intance of a class diagram in EMF?! Rolling Eyes

Thanks

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Re: 3 or 4 layers [message #758069 is a reply to message #758051]

Mon, 21 November 2011 20:32

Ed Willink

Messages: 7655
Registered: July 2009

Senior Member

Hi

M0 - User objects and values (EObjects and Java primitives - User Model)
M1 - User/Model classes (defined by EClass instances - Ecore Model)
M2 - Ecore Model classes (defined by EClass instances - Ecore Model)
M3 - Ecore MetaModel (defined by EClass instances - Ecore Model)

Self-describing meta-models do not need M>=3. The same is now true for
UML which describes itself rather than needing the extra recursion to
MOF at M3.

If you regard MOF as fundamental, then you would re-engineer Ecore so
that M3 is MOF rather than Ecore.

[I find usage of the M0, M1, M2 ... terminology to be associated with
misunderstanding more often than insight.]

Regards

Ed Willink

On 21/11/2011 20:08, elhamlaoui wrote:
> Hi Ed,
>
> I was hoping that i you were the one who answer to this, im lucky :)
>
> It deponds it could be M1 or M0(according to OMG layer), what I try to
> achieve is projection of the OMG layer on the EMF.IN the EMF i could
> got just model->MM->MMM(Ecore), if we take an example of a class
> diagram in UML:
>
> Instance class diagram-> class diagram-> MMUML->MOF
>
> What it would be the intance of a class diagram in EMF?! :roll:
> Thanks
>
>
>
>
>

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Re: 3 or 4 layers [message #758073 is a reply to message #758051]

Mon, 21 November 2011 20:36

Hallvard Traetteberg

Messages: 673
Registered: July 2009
Location: Trondheim, Norway

Senior Member

M0 is simply the instances of the modeled classes, e.g. Library and Book
instances. There is no Ecore diagram kind for this, usually you find
them in xmi files, e.g. the ones you get when creating a dynamic
instance by right-clicking on an EClass in the Ecore editor.

In my opinion, the levels are only meaningful relative to each other,
and usually you only need to think about two levels at a time: models
and (instance) data. When building model-based tools, I find it easier
to use these terms (model and data) rather than meta-model and model.

Hallvard

On 21.11.11 21.08, elhamlaoui wrote:
> Hi Ed,
>
> I was hoping that i you were the one who answer to this, im lucky :)
>
> It deponds it could be M1 or M0(according to OMG layer), what I try to
> achieve is projection of the OMG layer on the EMF.IN the EMF i could got
> just model->MM->MMM(Ecore), if we take an example of a class diagram in
> UML:
>
> Instance class diagram-> class diagram-> MMUML->MOF
>
> What it would be the intance of a class diagram in EMF?! :roll:
> Thanks
>
>
>
>
>

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Re: 3 or 4 layers [message #758077 is a reply to message #758073]

Mon, 21 November 2011 20:40

Vlad Gheorghe

Messages: 127
Registered: May 2011

Senior Member

I find this to be a pretty good overview on the subject:

http://www2.imm.dtu.dk/~pk/images/meta-levels.pdf

Regards,
Vlad

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Re: 3 or 4 layers [message #758106 is a reply to message #758073]

Mon, 21 November 2011 21:36

Philipp Kutter

Messages: 306
Registered: July 2009

Senior Member

Am 21.11.2011 21:36, schrieb Hallvard Trætteberg:
> M0 is simply the instances of the modeled classes, e.g. Library and Book
> instances. There is no Ecore diagram kind for this, usually you find
> them in xmi files, e.g. the ones you get when creating a dynamic
> instance by right-clicking on an EClass in the Ecore editor.

With GMF-Tooling you can get a specialized diagram kind for such
instances of the modeled classes.

Thus, while there is (not yet?) a generic object/instance diagram as
initially asked by elhamlaoui, there is a generic way to get one for
your model of interest.

Regards, Philipp

*
*
*
Philipp W. Kutter
*CEO, Dr. sc. ETH*
*Montages AG
Stampfenbachstr. 48
CH-8006 Zürich

tel: +41 44 260 75 57
mob: +41 79 338 06 17
web: *www.montages.com <http://www.montages.com/>*

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Re: 3 or 4 layers [message #759737 is a reply to message #758106]

Tue, 29 November 2011 19:26

Elhamlaoui Mahmoud

Messages: 268
Registered: March 2010

Senior Member

Hi,

the link proposed her, http://www2.imm.dtu.dk/~pk/images/meta-levels.pdf explicit my concern. According to it, if we focus on library model, we can see that library model(M1) is an instance of Ecore(M3) Where is The M2 in this case??

Any ideas?
Thanks in advance

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Re: 3 or 4 layers [message #759741 is a reply to message #759737]

Tue, 29 November 2011 19:45

Ed Merks

Messages: 33140
Registered: July 2009

Senior Member

Given the Library instance is M0, the Library model is M1, then Ecore is
M2, and the Ecore model for Ecore is M3. These layers are always
relative and there's no reason to think they should stop at 4 levels.
For example, given a Library instance M0, who's model is an XML Schema
M1, and we have an XML Schema for Schemas M2, which has an XML Schema
Ecore model M3, then we have the Ecore model for Ecore as M4. Of course
Ecore.ecore in platform:/plugin/org.eclipse.emf.ecore/model/Ecore.ecore
is itself just an instance and is M0. Your mistake is you're trying to
absolutely pin a particular thing to a given level, when the whole point
is that levels are relative. Going down are instances, going up are
models/descriptions of instances.

On 29/11/2011 8:26 PM, elhamlaoui wrote:
> Hi,
>
> the link proposed her,
> http://www2.imm.dtu.dk/~pk/images/meta-levels.pdf explicit my concern.
> According to it, if we focus on library model, we can see that library
> model(M1) is an instance of Ecore(M3) Where is The M2 in this case??
>
> Any ideas?
> Thanks in advance

Ed Merks
Professional Support: https://www.macromodeling.com/

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Re: 3 or 4 layers [message #759758 is a reply to message #759741]

Tue, 29 November 2011 20:45

Elhamlaoui Mahmoud

Messages: 268
Registered: March 2010

Senior Member

Hi Ed,
Thaks for the answer,Quote:

then Ecore is M2, and the Ecore model for Ecore is M3

, sorry but i dont see the diffrence between Ecore and Ecore model

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Re: 3 or 4 layers [message #759802 is a reply to message #759758]

Wed, 30 November 2011 07:02

Ed Merks

Messages: 33140
Registered: July 2009

Senior Member

It's a good example where something exists at multiple levels; maybe
that means you don't want to count it twice. But you've ignored the
example where there are 5 levels or maybe you think something got
counted twice there too?

On 29/11/2011 9:45 PM, elhamlaoui wrote:
> Hi Ed, Thaks for the answer,Quote:
>> then Ecore is M2, and the Ecore model for Ecore is M3
> , sorry but i dont see the diffrence between Ecore and Ecore model

Ed Merks
Professional Support: https://www.macromodeling.com/

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Re: 3 or 4 layers [message #1052924 is a reply to message #759802]

Wed, 01 May 2013 12:42

Elhamlaoui Mahmoud

Messages: 268
Registered: March 2010

Senior Member

Hi,
I found this link http://www.eclipsezone.com/eclipse/forums/t115395.html , according to the controversy discussion about the layers dicussed above.
Ed, you said that :"PS: I personally prefer Bezivin's definitions of such terminologies to those of OMG MDA" It surely an old post but i wonder if i could have please a reference to an article to know more about the definition of Bezivin.

Thanks in advance

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Re: 3 or 4 layers [message #1052929 is a reply to message #1052924]

Wed, 01 May 2013 13:00

Ed Merks

Messages: 33140
Registered: July 2009

Senior Member

I believe it was Huy Tran who made that statement./

/
On 01/05/2013 2:42 PM, Elhamlaoui Mahmoud wrote:
> Hi,
> I found this link
> http://www.eclipsezone.com/eclipse/forums/t115395.html , according to
> the controversy discussion about the layers dicussed above.
> Ed, you said that :"PS: I personally prefer Bezivin's definitions of
> such terminologies to those of OMG MDA" It surely an old post but i
> wonder if i could have please a reference to an article to know more
> about the definition of Bezivin.
>
> Thanks in advance
>

Ed Merks
Professional Support: https://www.macromodeling.com/

Report message to a moderator