Re: Keywords for "SMTP Service Extension for Content Negotiation"

At 03:06 PM 7/14/2002 +0100, Graham Klyne wrote:
>I'm uneasy about (appearing to) equate fax-specific with just T.30 -- I 
>think your last sentence carries the intent if not the desired precision 
>-- maybe:
>[[
>"fax-specific" refers to email enhancements that permit email to 
>negotiate, transmit and confirm the transfer of images in timely fashion, 
>like traditional fax.

My use of the T.30 term was intentional.  I believe it is precise, complete 
and correct.  It is THE technical definition of the world's use of the term 
"facsimile".

Or at least, that is my understanding.  If I am wrong, we should get a 
precise, complete, technical definition that IS correct from the folks who 
know such things.

In other words, my intent was to use "fax" as a technical term, rather than 
a more general term describing a concept or service.  It's not that the 
latter is irrelevant, but rather that it invites fuzziness and debate.


>>>- multi-recipient
>>
>>Internet mail permits a message to be addressed to more than one 
>>person.  For example, see the To and CC fields of this message.  T.30 
>>permits addressing a single receiving device.  Some fax store-and-forward 
>>services permit the sender to specify more than one receiver.  This is 
>>multi-recipient.
>
>If you mention fax store-and-forward, I'd suggest a comment to the effect 
>that such services behave in a fashion more like ordinary email than fax.

Well, no.  They negotiate content, during the T.30 phase of communication. 
And that phase is, of course, strictly one addressee per copy of the content.


>>>- LCD
>>
>>Least Common Denominator.  So, we are borrowing a term from math, to 
>>apply to our discussion of ESMTP/CONNEG, it is possible to receive CONNEG 
>>parameters for multiple recipients.  If the recipients have different 
>>capabilities, what capabilities should the sender use?  One possibility 
>>is to end the current SMTP session and then send each recipient the best 
>>content they can receive.  Another possibility is to find the 
>>"intersection" of capabilities for all the recipients and send this 
>>"least common denominator" or "most common format" to all of the 
>>recipients at once.
>
>This term has often puzzled me as being incorrect in its mathematical 
>allusion.  The terms "greatest common divisor" or "highest common factor" 
>seem more apposite.

I agree but dislike those terms.  They sound yucky.

(Or perhaps it will be more constructive for me to note that they are not 
in common use and hence will have no intuitive appeal.)

Can someone suggest a term that is more palatable?


>>The primary difference between relaying versus direct is that relaying 
>>might take much longer.  Therefore the sender does not know when it will 
>>receive a response.
>>
>>On the Internet, a direct connection usually has a response time of a few 
>>minutes, maximum.  Normally it is much shorter, of course.  For email 
>>relaying, response time can be days, not minutes.  This difference in 
>>latency requires different design choices.
>
>I think there's a more fundamental architectural issue that is exploited 
>by traditional fax operating in a non-relay mode:  normal operation 
>requires that the sender can receive some indication from the receiver 
>before it starts to send any actual data.

You are saying that this is different from getting a 250 in response to an 
RCPT?

How is it different?

d/

----------
Dave Crocker  <mailto:[email protected]>
Brandenburg InternetWorking  <http://www.brandenburg.com>
tel +1.408.246.8253;  fax +1.408.850.1850