On Mon Feb 20 15:15:23 2006, Eric Rescorla wrote:
So, what I'm arguing is that except for applications where initial
connection setup is a large fraction of the cost of the entire
connection, I think it's not worth optimizing the initial connection
setup very much. And until you've profiled the protocols in
question it's hard to know which case you're in.
I'll have to disagree almost totally.
I think you always basically know what case you're in, because the
connection setup time is wasted time that's not achieving anything
useful, it's just staring-at-the-screen time. For a purely
non-interactive protocol that a real human will never be waiting for
results from, I suppose you could ignore any setup RTT cost, but I
struggle to think of an example for this.
For IMAP, where connection setup time is, in principle, a very small
part of the total session time, it seems odd you're advocating that
nobody should worry about adding round-trips when there's been
substantial effort in reducing round-trips in precisely this area.
Witness the way that the CAPABILITY command has been deprecated into
a CAPABILITY response code, or the SASL-IR proposal, or RECONNECT -
the list just goes on.
Moreover, this phase of "reading your mail" is one where the user is
definitely watching, and essentially nothing useful is happening. You
absolutely know this is a good place to optimize.
>> Is it true that we no longer need to worry about regularly adding
>> extra round-trips to popular protocols that operate over the open
>> Internet?
>
> No.
>
> As far as I'm aware, there is no protocol in existence which
somebody,
> somewhere, does not actively use over a mobile phone link, or a
slow
> analogue modem, and this is especially true of TLS enabled
protocols
> such as HTTP, email protocols, etc.
Well, I hear what you're saying, but when I check my mail over my
cell phone, it's pretty clear that the time isn't going to TLS
connection setup.
Nope, but I'll bet that the time you spend waiting, rather than
reading, is almost entirely round-trip latency, and not actual useful
octets coming through the ether - silent noise and not shifting bits.
Dave.
--
You see things; and you say "Why?"
But I dream things that never were; and I say "Why not?"
- George Bernard Shaw
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