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RE: Back-channel: What is it and where do I find it?

From: <paul.downey@bt.com>
Date: Mon, 6 Nov 2006 20:59:44 -0000
Message-ID: <2A7793353757DB4392DF4DFBBC95225504BFF004@I2KM11-UKBR.domain1.systemhost.net>
To: <dmh@tibco.com>, <public-ws-addressing@w3.org>

Hi David,

Let me see if I can spring a few of your traps :-)

I assume that a "back-channel" is some magical combination of a 
return address and message correlation implicitly supplied by 
the underlying mechaninsm by which messages are being exchanged.

In other words, request-response just works.

I'm guessing you are asking for us to define that in more formal
terms in our spec, assuming we add the term?

>    * Does email have a back-channel?

Reply-To, MessageId/In-Reply-To, it's certainly possible:

http://www.w3.org/TR/soap12-email

>    * Does a raw TCP connection have a back-channel?

possibly, if you place significance on the order of messages.

>    * Does a raw UDP packet have a back-channel?

nope.

>    * Does BEEP have a back-channel?

er, possibly, depending on the profile. 
A bit like asking if Java has polynomials, no? 

RFC3288's http://iana.org/beep/soap supports the request/response MEP

>    * Does XMLP <message/> have a back-channel?

er, SOAP abstracting away the transport is why we're here ..

>    * Does XMLP <iq/> have a back-channel?

doesn't SOAP over XMPP use one?
http://www.xmpp.org/extensions/xep-0072.html#binding-operation-request-sendingreceiving

> and finally ...
>
>    * If a binding tells me "I have a back-channel", just what can I
>      count on?

request-response. probably.

Paul
Received on Monday, 6 November 2006 20:59:58 GMT

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