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Re: RSVP: Resolution to issue #29 satisfactory? (fwd)

From: Dan Brickley <danbri@w3.org>
Date: Thu, 1 Nov 2001 10:16:20 -0500 (EST)
To: Christopher Ferris <chris.ferris@sun.com>
cc: Jacek Kopecky <jacek@systinet.com>, <bprice@us.ibm.com>, <xml-dist-app@w3.org>
Message-ID: <Pine.LNX.4.30.0111010944190.29201-100000@tux.w3.org>


On Thu, 1 Nov 2001, Christopher Ferris wrote:
> Jacek Kopecky wrote:
> >  Dan, Barbara,
> >  can you please elaborate on why using SOAP Data Model and SOAP
> > Encoding is the preferred way for you?
> >  In my opinion if a SOAP message is to carry RDF or XMI data, the
> > data should be present in their "native" form, I don't see a
> > reason for transforming the data to SOAP Data Model.
> +1

-1 ;-)

There's a process difference between XMI and RDF here. RDF is a W3C
recommended mechanism for structuring and encoding graph data in XML. W3C
WGs have invested a fair amount of time on it, and we have chartered work
to invest more. It may well be that SOAP, XML Protocol, Web Services etc
have different needs and need to adopt different techniques for graph data
encoding/exchange. This is fine. But we shouldn't be casual about creating
further divisions between W3C XML languages: if RDF maps into the
SOAP-encoding model, we gain a common approach to structured data exchange
in the Web. If it doesn't, that's a shame, life goes on. But I want to
hear a clear account of what SOAP-encoding is *for* if I'm to adopt
the view that RDF (and XMI) apps shouldn't expect to use it. If RDF and
XMI developers shouldn't expect to find any use in the SOAP-encoding
mechanism, who should? Topicmaps folk? semi-structured database developers?

RDF, I believe like SOAP-encoding (and maybe XMI?), uses XML + namespaces
to represent edge-labeled graph structures for data interchange in the Web.
There are tools, libraries, databases etc in each tradition. The SOAP
spec for example calls out semi-structured databases as a motivation
behind the choice of data model; RDF made the same choice for similar
reasons. At this stage in SOAP's development (ie. when the Data Model bit
of the spec isn't completed) I believe it premature to say "RDF is a
different, alien data format; we'll carry it through in its own syntax".

It may well be that RDF is significantly and interestingly different from
the SOAP-encoding data model. In that case, using RDF's native XML encoding
makes sense. But if the models are close, and if SOAP tools/applications offer
useful services based on the existence of the SOAP data model and
encoding syntax, we should think carefully before saying that this part
of SOAP is useless to a whole family of W3C work.

My hope is that, as the SOAP Test Suite work (re encoding) matures and the
Data Model section of the spec becomes more explicit, we'll gain a clearer
understanding of how SOAP-encoding relates to this other area of W3C work.

Until we get to that stage, it seems premature to say "SOAP-encoding
was designed to support the exchange of semi-structured XML graph data;
except for RDF and XMI and ... (topic maps too?), for which SOAP apps
should exchange using the native encodings for those formats".
This to my mind undercuts the value of having a SOAP-encoding specified
at all. It focusses attention on the need for the spec to say more clearly
when we should expect XML-protocol based web services to adopt the SOAP
encoding and data model.

Short version: "what is SOAP-encoding for? what is it *not* for?"


Received on Thursday, 1 November 2001 10:16:24 UTC

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