Re: [model] section 3.2.4 Metadata

<Sorry if you get this twice - I removed the digital signature, which
seems to cause problems in people being able to see the email>

I see very little value in section 3.2.4.1 - mostly it is a long winded
definition of metadata and only a small part of it says anything about
how
it relates to the ForCES model.

Isn't the paragraph under 3.2.4 sufficient to describe what we mean by
metadata in the ForCES model? (e.g. it is the per-packet state that is
passed from one LFB to another and that the only metadata model that is
of
concern to the ForCES model is the metadata that is passed from one LFB
to
another within an FE).

If no one will have heartburn about removing section 3.2.4.1, I will
take it
out and try to work on rewriting the rest of the section to make it more
readable.

Regards,
Ellen

-----Original Message-----
From: Forwarding and Control Element Separation
[mailto:[email protected]] On Behalf Of Jamal Hadi Salim
Sent: Friday, December 29, 2006 7:56 AM
To: [email protected]
Subject: Re: [model] section 3.2.4 Metadata

On Thu, 2006-28-12 at 15:14 -0500, Joel M. Halpern wrote:
> You could as well ask "where are the formal semantics of an LFB class 
> defined?"  After all, the CE has to understand what the FE will do 
> when asked to put an instance of an LFB class on a data path.
> 
> The decision we took was to not formally define semantics.  Semantics 
> are defined textually.
>
> This is true of LFB operations.  It is also true of meta-data 
> semantics.  Typically, some LFB will produce the meta-data, with text 
> indicating that the meta-data is some result of manipulating a field 
> in a packet, or an entry in a table provided by the CE, or ...
> (Yes, there is room for ambiguity.  Writers of the text describing 
> LFB classes need to do their best to make sure the English is clear.)
> And another LFB might indicate that it uses some piece of meta-data 
> as an index in a table.
> 

Actually looking further into the text, I think i have found my answer
in the schema. Are we both exhausted of this text?
The definition of the metadatum is done in the LFB class (section 4
shows it). Your example has <metadataDefs> and its usage well done in
section 8. That helped.
I think it would do a lot of justice to have the text on metadatum to
reflect the simplicity found in section 4. A cleanup of the text is
certainly needed.

More suggestion:  add some text on LFB capability of metadata - maybe a
small extension to your example in section 8 would be useful.

cheers,
jamal