Re: [imap5] Beep

[Dave Crocker <[e-mail]>]

On 5/10/2012 9:22 AM, Tony Finch wrote:
> Dave Crocker<[e-mail]>  wrote:
>>
>>     Multiple simultaneous TCP connections are highly problematic.
>>     Especially for new protocols.
>>
>> The real world of today's Internet makes it difficult to ensure proper
>> operation through firewalls and application gateways.
>
> Well they aren't great for congestion control and window sizing, but

a multiplexing mechanism always has those issues, where the underlying 
issue is making sure that a problem in one sub-channel does not block 
the others.

multiplexing adds complexity.  it's always better to find a workable 
solution that does not require it.


> middleboxes should only be a problem if you are doing FTP-style layering
> violations.

I don't have a guess about what layering violation you think FTP does...


So concurrent connections are normal for HTTP and IMAP and

I was careful to say "new" protocols.  And I think I was careful to cite 
use of different port numbers. (I certainly meant to be.)

Parallel identical connections for protocols that already punch through 
firewalls are in a very different position of strength than new 
protocols.  However even these are problematic for gateways.  On the 
average, we don't design for concern about gateways, but the issue still 
exists.



> Everything over port 443.

well, that's obviously far better than everything over 80...

And while I mean that ironically, there's a kernel of reality to it: 
Beep was produced in response to the clear trend to put everything over 
http.  Beep is lower cost, by quite a bit.

It then adds back some cost with the multiplexing mechanism, of course. 
  But that's why it replicates established multiplexing mechanisms from 
lower layers.


For reference, I'm not lobbying for it's use, here.  I don't have an 
opinion for the IMAPnextgen discussion, but wanted to clarify why beep 
was a long way from crazy.

d/
-- 
  Dave Crocker
  bbiw.net