[collectd] rrd2flot: Client side canvas based charting of collectd rrd data

[Richard Wall]

On Mon, Apr 26, 2010 at 1:57 PM, Lindsay Holmwood
<lindsay at holmwood.id.au> wrote:
> The Comet idea is cool, but AFAIK gRaphaël doesn't support live
> updates of graphs. Definitely on my wish list though.

Hi Lindsay,

Sorry for the delayed reply.

Flot sort of does - as long as the axis labels don't have to change.
Otherwise you have to re-render the entire chart, but on latest
browsers this is pretty fast.

> You'll have lots of fun serving up the RRDs directly in the browser
> and dealing with each plugin's eccentricities client-side. That was
> how I originally designed Visage and it brought me a world of pain.
> I've recently refactored the client-side code and moved all of that
> data crunching to the server, and graphing is *significantly* faster
> and easier to understand.

The javascriptRRD library does a very good job and seems to work on
IE, Firefox, Chrome. The major problem is the lack of canvas support
in IE and the slowness of the excanvas workaround.
However, you can get around that by prompting the user to install Chrome Frame:
 * http://code.google.com/chrome/chromeframe/

There does seem to be a pretty major memory leak somewhere in
javascriptRRD / Flot / ??? - if I refresh a page containing ~10
charts, the browser memory use soon gets out of control.

-RichardW.