[nycphp-talk] So why is Ajax so fast?
jonbaer at jonbaer.com
Fri Jan 12 11:04:45 EST 2007
This really depends on the library you are using and getting the
server and XHR cache to work in sync w/ content-negotiated responses.
There is a bunch of stuff if you Google "XHR caching". However I
usually put this step in the "tuning" category when you are testing,
there are a few testers out there (Selenium I think?) which will
automate and give you a report. The unit tests for these libraries
usually have some details on what it's doing.
On Jan 12, 2007, at 9:58 AM, Kenneth Downs wrote:
> We've all seen the amazing results you can get when you start using
> Ajax, they all come down to one thing: speed.
> Question is, how is such a speed-up accomplished? The standard
> answer is that a complete trip to the server is averted, but this
> is not true, in fact a complete cycle does occur:
> 1) Request to server
> 2) Possible db access on server
> 3) rendering of HTML on server
> 4) delivery to browser
> 5) re-rendering of portions of screen
> Supposedly the js and css libraries are cached so we have not saved
> the effort of retrieving them, this means the only thing we have
> saved is the effort of re-rendering the screen from scratch. To
> put another way, we have not saved a whole lot of bytes of traffic,
> or CPU cycles on the server. The only thing that seems to be
> missing is the render-from-scratch on the browser.
> Is this correct? And if so, why is it so dramatically expensive to
> render a page from scratch, that Ajax could make such a dramatic
> improvement to the situation?
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