Re: [sip-clf] FW: New Version Notification for draft-niccolini-sipclf-ipfix-02

["Saverio Niccolini" <[e-mail]>]

Dear Vijay,

> Saverio: Thanks for getting this out.  I am not sure I understand
> the mechanics of ipfix completely, but the draft helps me
> conceptualize the approach a bit more.

If there is something unclear, let us know such that we can improve it
in the next version of the draft.

> In any case, I had one comment on Section 5.  The text presented
> in S5 is more of a data model than an information model. 

Indeed, we supposed we refer to your draft for the place where the
information model is defined (or any draft that does that), we just 
follow what the draft say and we implement it in a data model following 
IPFIX principles.

> If I read rfc3444 correctly, a "data model" determines the structure
> of data elements (including legal values for the contents of these)
> and the relationship among the data elements.  An "information
> model", on the other hand, is the modeling of entities in a
> system and their relationship (these are, fortunately, the
> most generally accepted definitions for the terms in the
> industry and academia.)

yes, we are on the same page.

> The problem-statement draft already contains a data model [1]
> that I have been using for a long time [2].  In the next revision
> of the problem-statement draft I am working on now, I will
> present a more formal definition of the data model, including
> the relationship between the data elements (some of which is
> captured in the precursor draft [2].)  I think it may be best
> to leave the data model in one place --- the problem-statement
> draft --- and have the individual solution drafts show the
> format of the sipclf record.

Here we need some clarifications:

-- (in my opinion) you can not define a data model if you first do not 
define an information model, the data model is a mapping of your information
model into particular data structures (it is like the "implementation"
of the "concepts" defined in the information model, the relationship needs
first of all to be defined in the information model)

-- (in my opinion) Section 8. of your draft [1] contains a start to 
the definition of information elements to be included in the 
information model, the information elements are independent from the
particular data model chosen, the relationship needs still to be defined

If you want to see what I mean by the differences between information
model and data model, you can refer to another piece of work I did for
the traceroute use case: http://tools.ietf.org/html/rfc5388 

My understanding was that the information model should be common and
thus described in only one place, but we will have multiple data models 
(one ASCII and one binary/IPFIX).

What is your view on that? 

Also: I do not think a problem statement draft is the right place to 
place an information model and a data model, maybe we need separate drafts
for that.

Maybe we need:
-- one problem statement
-- another draft where we describe the information model and the two data
models?

> I would love your feedback on the data model and its contents
> once I get the updated problem-statement draft out later this
> week.

I can give feedback on that but would like to clarify the strategy moving
forward and which draft needs to address which points (problem statement,
information model, data models)

Thanks,
Saverio

> 
> [1] http://tools.ietf.org/html/draft-ietf-sipclf-problem-statement-01
> [2] http://tools.ietf.org/html/draft-gurbani-sipping-clf-01
> 
> Thanks,
> 
> - vijay
> --
> Vijay K. Gurbani, Bell Laboratories, Alcatel-Lucent
> 1960 Lucent Lane, Rm. 9C-533, Naperville, Illinois 60566 (USA)
> Email: vkg@{alcatel-lucent.com,bell-labs.com,acm.org}
> Web:   http://ect.bell-labs.com/who/vkg/

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Dr. Saverio Niccolini
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