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RE: Closing on NIM requirements

Actually, I think you can almost always find a mapping convention from some
high-level modeling concept to any low-level implementation (Ie. Multiple
inheritance to Single inheritance with associations simulating multiple
inheritance). The point of the high-level model is that it should be easy to
model your information with it... It is for the modeler who knows what the
data needs to be but not how specific implementations work (or what their
particular quirks may be). Using the conventions of the high-level model,
standard mappings can be developed for specific implementations (ie. a
high-level two-way association maps to an SNMP table entry with a successor
+ predecessor row pointer). Standard mappings will hopefully make the
translation automatic. 

Besides being most convenient to the modeler, the high-level model must be
maximally expressive, allow the modeler to specify constraints, etc. such
that the resulting model is unambiguous (and, thus, so are the mappings).

Basically, we need a simple way to get the information out of the expert's
heads and into a high-level model (once), then derive the low-level models
from that root model.


> -----Original Message-----
> From: Jon Saperia [mailto:saperia@mediaone.net]
> Sent: Sunday, April 16, 2000 2:43 PM
> To: Harald Tveit Alvestrand; Durham, David; 'Weiss, Walter';
> 'nim@ops.ietf.org'
> Subject: Re: Closing on NIM requirements
> > I have a stated a preference for UML in the past. The 
> interesting question
> that this discussion begs is: if people believe LDAP and SNMP 
> (and others)
> are not able to effectively represent what is in the 
> 'higher-level' models,
> what should be done? I have mentioned a number of times that 
> the technology
> specific details, whether they be LDAP, SNMP, or anything 
> else will always
> tend to impinge on the higher layer modeling. Even in what 
> are generally
> considered to be OO languages, there are important 
> differences. For example,
> how do I do multiple inheritance in Java?  The point is not 
> to pick on Java
> or any other technology. My point is that either the modeling 
> language be
> reduced to the least common denominator - which probably 
> nobody wants, or a
> plan be put in place to bring up the infrastructure elements 
> to the point
> where they have what people feel is needed. In that case a 
> fairly protracted
> but appropriate discussion of tradeoffs would probably have 
> to take place.
> /jon