[time-nuts] web presentation of data

Chris Albertson albertson.chris at gmail.com
Tue Aug 7 15:56:34 UTC 2012

On Tue, Aug 7, 2012 at 6:45 AM, Jim Lux <jimlux at earthlink.net> wrote:

> On 8/6/12 10:43 AM, Chris Albertson wrote:
>> On Mon, Aug 6, 2012 at 8:34 AM, Jim Lux <jimlux at earthlink.net> wrote:
>>  what would be useful is to have some sort of "plotting engine" that is a
>>> canned webpage (or stored locally on the user/client computer) that can
>>> ingest fairly raw data from a URL..
>>> something, conceptually, like this:
>>> <BODY>
>>> *invocation of plotting engine*
>>> data value 1
>>> data value 2
>>> data value 3
>>> </BODY>
>>>  What you are saying is that the data needs to be rendered to a graphic
>> locally.   I think the simplest way is to create vector based plots on the
>> server (I've used GNU Plot inside a CGI script) but there is a system to
>> pretty much what you are asking for.  http://code.google.com/p/flot/
> Somehow, I don't think running Gnuplot on a Arduino is feasible.  ABout
> all it can do is respond to the HTTP "Get" with the right page.
> That's why I want to push the hard work of doing the rendering onto the
> client (i.e. the browser).  The comm link is fast, and an SD card on the
> Arduino can hold tons of stuff, so serving a page containing 100kbytes of
> Java or similar isn't a problem.  But doing any computation is probably not
> in the picture.
So the web server is inside an Arduino?  Yes can't run GNUplot there.   Why
not have the Arduino produce either Postscript or PDF?  It is very easy to
draw a graph in Postscript.  Postscript is just ASCII text that contains
statements like "Draw a line from (2.34,6.65) to (3.45,78.4)" You can draw
using your application's natural units, then you apply a transform to map
those to output units like inches or cm.   Later the web browser or the
printer turns those draw commands into a rasterised image fro display.
 Postscript is very compact.  A few KB would be more than enough for a
graph.     The advantage is that the output resolution is "perfect" because
your lines are drawn using natural units with as many places after the
decimal point as you like.   So your users can zoom in if they want to
1000X zoom and see details, not pixels.    It wil fet on any screen

Also everyone already has the display engine.  PDF is very much like
Postscript. but I think Postscrip in "EPS" form is easy to create inside an


Chris Albertson
Redondo Beach, California

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