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FAST Protocol
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Re: Weigh-in please - Template format: XML and/or Compact Notation
Matt Simpson / Chicago Mercantile Exchange
19 Apr 2006 5:55PM ETThere are several good ideas circulating here. I agree that we need to separate the concept of template representation from the template wire format.
At the point template exchange is introduced as a part of SCP (future release) it makes sense that a special Template Exchange format will be used to convey the structure of a template. Neither XML nor compact notation will be sent across the wire. These are only to be used as the 'human interpreted' form of the data structure as coined by Scott Atwell. The SCP template format will be closest to a machine-level representation.
So the question of compact notation vs XML becomes one of what's best for purposes of readability - how should I represent my message structure so that it is most intuitive to those reading it? For those accustomed to FIX tag/value the answer is probably compact notation since it emphasizes tag numbers in a format that evokes a FIX message. For those more comfortable with XML, then obviously TD-ML makes most sense.
My vote at this point is to keep both
> You're absolutely correct, the SCP templates would be hard wired with
> reserved templates identifiers.
>
> > I had thought about this, but it wasn't immediately clear to me how
> > you could parse any FAST message without first having a template. How
> > would the FAST message containing a template be parsed without first
> > having a template?
> >
> > I suppose we could standardize the template for transfering templates.
> > Essentially reserve template id 1 for passing templates around, and
> > all FAST engines would have this template preloaded. Is that what the
> > document described?
> >
> > > I don't know the distribution of that version of the document, but
> > > an earlier draft of SCP contained messages for template exchange,
> > > i.e. the templates were transmitted as FAST messages themselves.
> > > This makes transfer efficient, which is nice if you would like to
> > > replace a template mid-day for instance or if you use extremely short-
> > > lived sessions. More importantly, your existing FAST processor can
> > > be reused so that no additional parser is needed.
Re: Weigh-in please - Template format: XML and/or Compact Notation
Matt Simpson / Chicago Mercantile Exchange 19 Apr 2006 5:55PM ET
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