Re: NSURLConnection Latency on iPhone
Re: NSURLConnection Latency on iPhone
- Subject: Re: NSURLConnection Latency on iPhone
- From: Josh Graessley <email@hidden>
- Date: Tue, 06 Jan 2009 17:20:20 -0800
On Jan 5, 2009, at 10:13 AM, james woodyatt wrote:
On Dec 29, 2008, at 15:38, Josh Graessley wrote:
It's frustrating to watch the carriers tote faster and faster
speeds without any mention of latency when high latency is really
what makes cellular internet a painful slow experience.
That's a frustration we're going to need to get over, sooner or later.
The high latency is what it is because of physical and media access
layer issues related to metro-area wireless mobility. We'll
probably see more improvements in bandwidth to come as various parts
of the spectrum open for use with more efficient physical encodings,
but the latency is unlikely to improve for the foreseeable future.
If you ask me: the *only* way to get over that latency problem is to
fix the Internet's broken session and presentation layers for
application protocols. (You'll probably get other answers from
other people. It's a contentious topic.)
The frustration is not in the fact that latencies aren't imporving.
It's that
1) People are oblivious to latency and do a bad job of designing
protocols, resulting in latency bound protocols such as HTTP
2) Companies that provide wireless internet service unrealistically
set the expectation that higher bitrates mean faster browsing
3) While pipelining exists to make HTTP less latency bound, it isn't
usable in practice because deployed stuff is so busted
I think one of the biggest problems is making people aware of the
impact of latency from those that design websites to those that design
protocols. A lack of knowledge of other behaviors that affect network
performance also causes problems. Things like TCP slow start can have
repercussions: 4 connections to load 4 resources is more likely to be
slower than a single request over a single connection for those same
four resources. People designing websites with zillions of tiny files
spread across many servers and various scripts and files that make
generating a short list of resource dependencies are oblivious to the
performance problems they're creating.
-josh
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