[Phpmyadmin-devel] Realtime charting

[Tyron Madlener]

On Tue, May 31, 2011 at 10:13 AM, Michal Čihař <michal at cihar.com> wrote:
> Hi
>
> Dne Tue, 31 May 2011 00:12:31 +0200
> Tyron Madlener <tyronx at gmail.com> napsal(a):
>
>> I've added now a first version of my planned realtime charting on the
>> status page in the 'Query statistics'-Tab (click on "Realtime chart").
>> You can check it out at http://demo.phpmyadmin.net/gsoc-tyron
>>
>> Currently it aggregates the average queries per second by making an
>> ajax request every 2-2.5 seconds (2 seconds + time for one ajax
>> request). Since it is using the differential of the status var
>> 'questions' it takes some seconds to display a line.
>>
>> For the chart I'm currently using Highcharts because it allows
>> realtime data, animates beautifully, is really small (1 file, 77kb
>> minified) and has a export to png/pdf/jpg plugin (6.4kb minified)
>> which however uses a highcharts.com server for the conversion.
>
> Depending on external service is not something I would like to see.

Thats indeed not very nice. Maybe with some hacking around I could
build my own svg to png/pdf converter for phpmyadmin. There must be a
library for that. The code for converting the charts is availabe from
highcharts.com, but from what I've seen its partially written in java.
But it cannot be that hard to build our own php-only-solution.

>
>> Some radical suggestion in this regard: What about removing the
>> included pChart and instead using a client-side charting library? I
>> know for some part its bad since a student wrote a whole lot of code
>> for it just last year, but looking at some requirements for phpmyadmin
>> (no file storage, limited possibilities for data recording,
>> panning/zooming, realtime updates) a server-side charting library
>> offers much less possibilities compared to a client side-one. And if
>> we'd use highcharts it would save us like 16 files and 750kb (well
>> most of it is that dejavu font).
>> I think it would be pretty easy to replace actually. Instead of the
>> graph, the server-code would just need to send the already generated
>> chart data hidden in the document and then we add a bit of js code to
>> display the chart. Some code from chart.lib.php is probably reusable.
>
> There has been lot of discussion what to use and we stick with sever
> side solution because it did allow saving of the images (what might
> be not that useful for server stats, while is definitely useful when
> drawing chart from query results) and does not require javascript
> (though this is less and less important nowadays).

Actually the way how pChart is currently implemented it generates the
charts in slices, so at the moment you cannot save them.

>
> However for realtime charts, server side solution will indeed
> perform worse. And there is also need for some client side graphics
> library for spatial extensions, so I'd like to see one client side
> library used for both drawing spatial data and for charting.
>

I basically agree, since adding more and more libraries creates only
more feature creep and inconsistency.
The reason I'm not very fond of using the suggested svg drawing
library (jQuery SVG) is that it has not been specifically built for
charting. The plotting examples on the website look rather clumsy and
I couldn't find any support for real-time data.

So, if I'm going to build real-time charting for pma using jQuery SVG,
I will have to write and maintain some sort of
real-time-charting-plugin that likely will consume between a few days
and a week of time.

It seems more "future-proof" for me to invest that time in replacing
pChart with a client-lib like highcharts and thus still having only 2
graphing libs in pma.

> Whether it will be possible to replace pChart or not later, that's IMHO
> different question (mostly depending on usable way of exporting charts
> out of client side solution).

pChart is currently used only in 3 different place, no?
- server status page
- query profiling pie
- query result charting

When I was looking at the code, it seemed fairly easy to replace it.

I will do some research on the code of highcharts export, jquery svg
and pchart the next days so I can make a more exact estimation of the
time it would require to add the missing requirements or replace with
another lib in the case of pchart.

As always thanks for all the feedback and more is always welcome :)

>
> --
>        Michal Čihař | http://cihar.com | http://blog.cihar.com
>
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