RE: [mdr-users] Metalevels

Strictly speaking MOF is M3 and the other levels you have are M2 and M1.
You're right that the actual Java structures would be M0.

However please don't get too hung up on these different levels: the whole 4 layer model was really only intended as a framework to introduce people to the concepts. In reality life is not so simple, and one can have the same model spanning multiple levels.
A more useful scheme is what I call N+1-1: you have a metamodel (N) which is an instance of MOF (N+1) and which can have instances/models (N-1).
The same can be applied to models as opposed to metamodels: you could have a model of Organization Structure (N) which is MOF (N+1) compliant and which can be instantiated in MDR to hold actual organizations (N-1).
Is the Organization Structures model actually a metamodel? It does not matter and IMHO it's totally futile to argue about it.

Let's say you combine the Organization Structure model and UML (meta)models into a single clustered (meta)model, which also adds a new Association called Ownership between Organization in Organization Structure and Package in UML, and create a repository from this.
We can now link a specific organization (e.g. Sun) with a specific UML package (e.g. an Accounting model).
There is no problem at all with the technology or the usefulness: this is something my company does all the time to help people manage their models.
However to some who take the 4 layer model too seriously this is heresy since it combines M1 (the UML package) with M0 (the specific organization).

Hope that helps,

Pete

Pete Rivett (mailto:[email protected]) 
CTO, Adaptive Inc. 
Dean Park House, 8-10 Dean Park Crescent, Bournemouth, BH1 1HL, UK 
Tel:  +44 (0)1202 449419 Fax: +44 (0)1202 449448 
http://www.adaptive.com 


 

> -----Original Message-----
> From: ludger goeke [mailto:[email protected]] 
> Sent: Friday, June 10, 2005 3:46 PM
> To: [email protected]
> Subject: [mdr-users] Metalevels
> 
> 
> Hallo Martin,
> 
> I wrote in the MOF 1.4 specification about the four Metalevel 
> M3,M2,M1,M0.
> I´m trying to implement the UML2 Compositestructure with the MDR.
> I´m not sure wether I only use three Metalevel.
> 
>    M2 Level   ->  MOF Model ( version 1.4)
>    M1 Level   ->  Metamodel of the CompositeStructure 
>                   ( as a Part of the UML Metamodel )
>    M0 Level   ->   Composite Structure Models
> 
> Am I right when I consider the Composite Structure Models as 
> the concrete
> data that I work with, or do I have to consider the actual 
> java objects that
> represent a Composite Structure Model in the mdr, as "MO Level data" ?
>  
> Regards Ludger
> 
> -- 
>       
> 
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