W3C home > Mailing lists > Public > xml-dist-app@w3.org > July 2001

Re: Protocol Bindings

From: Marc Hadley <marc.hadley@sun.com>
Date: Thu, 05 Jul 2001 11:59:14 +0100
Message-ID: <3B444882.988127B2@sun.com>
To: eamon.otuathail@clipcode.com
CC: xml-dist-app@w3.org
Eamon O'Tuathail wrote:
> To get interoperability, surely we need to define both the envelope
> encapsulation *AND* how it gets exchanged over an application protocol.

> There may be many (M) encapsulations (text, binary, multi-part) and there
> may be many (N) application protocols (BEEP, HTTP, Custom over TCP) and it
> is better to define each just once, so rather than M*N definitions, we have
> M+N definitions.

> If you want to send me a SOAP envelope, it is no good us agreeing on the
> layout of the octets if we can't agree on how to decide where one message
> stops and the next begins (framing).  This, and a number of other services,
> are provided by an application protocol.
> We can argue whether BEEP or HTTP or whatever is better as an application
> protocol, but the general services they provide are needed - and some piece
> of functionality must provide them. Hence I think the diagram at:
> http://www.w3.org/2000/xp/Group/1/04/23/XMLProtocolAbstractModel.html#Sec5.1
> .1
> is wrong.
> The TCP column (left-most column) is completely missing an application
> protocol. TCP is not providing you with framing (etc.) - so which component
> is? There should be a small box in that column identifying this component,
> with a name such as "custom". Both you and I might be able to handle TCP
> connections and might be able to understand SOAP XML 1.0 envelopes - but
> that still does mean we can communicate - we also need to agree the details
> in the middle - how the encoding is carried in the transport.
In the case of the diagram, the framing *could* be included in the
"binding" specification. i.e. the small box you refer to could be
encapsulated within the "binding" box. But (see my message at [1]) it
would probably be better to define a common packaging format (the small
box) that is reusable in any stream based protocol.


[1] http://lists.w3.org/Archives/Public/xml-dist-app/2001Jul/0019.html

Marc Hadley <marc.hadley@sun.com>
Tel: +44 1252 423740
Int: x23740
Received on Thursday, 5 July 2001 06:59:36 UTC

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