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

Paul,

Yours is the third eminently reasonable answer I've received on this. 
They all differ.

The points being 1) Of course we have to define it if we're going to use
it.  2)  Agreeing on a definition is quite likely feasible, but
certainly not trivial, so I'd like to know what we get for the effort if
we go there.

paul.downey@bt.com wrote:
> 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
>
>
>