[En-Nut-Discussion] Web Charts? Use java?

[José Vallet]

Tim Tait wrote:
> 
> José -
> 
> I am also a java newbie.
> 
> Real time data update via socket sounds cool, but that applet looks 
> pretty big. How small did you get it?

Do you mean the one shown at jchart2D web page?

I changed that one a bit and now it includes 2 charts (linear and 
histogram like), 5 slider controls (with entry type and range checking), 
1 button... but it will grow.

I managed to put it all in a 73Kb .jar (before optimization it was 
137Kb) I use the entire flash for the web server, so in my opinion it 
can still grow a lot more.

> 
> What I did was very simple - you have to refresh the page to get new 
> data, but it should do what I need.

I cannot do that because I need "real time" measurements and data 
presentation. Refreshing the page seems slow, and adds unnecessary 
overhead to the process (all the httpd stuff). On the other hand the 
applet is downloaded only once in the whole process, and the data 
presentation is really fast (is done by the computer). The only extra 
thing to do at the Ethernut side is the socket communication and data 
sending.

I was trying to post an example in the list (binaries), so you could 
easily test it by yourself, but it was too big for posting it (172Kb the 
.hex plus 117Kb the xflash.bin) (Sorry Harald for that, simply didn't 
notice!)

The xflash.bin includes all the web files of the httpd example plus the 
.html that has the applet inside (1 line of code). So the gui itself is 
basically 73kb (you have 512Kb in the flash)

If you are interested let me know and I will send you personally the 
binaries and instructions about how to run the example, so you can judge 
by yourself.

Regards
José


> 
> Tim
> 
> José Vallet wrote:
> 
>> Hello Tim
>>
>> That is exactly what I am doing.
>>
>> What I have at the moment:
>>
>> ETHERNUT SIDE: http server + web page with an applet inside
>>
>> DESKTOP SIDE: web browser with Java.
>>
>> I am reading ADC data from Ethernut and sending it to the applet 
>> through a socket on real time. I use the library jchart2d for the 
>> charts http://jchart2d.sourceforge.net/
>>
>> I chose it because its simplicity compared to others and because it 
>> was exactly what I wanted.
>>
>> The resulting applet is packed in a .jar file with all the needed 
>> classes, and after that optimized and obfuscated for optimal code size 
>> using proguard (this step shrinks the applet size in about 30%!). That 
>> has proved to be the best for me, although it took me a while to make 
>> it work (I am a Java beginner).
>>
>> As the size of the applet is growing, I use the serial memory for 
>> storing it (xflash from Michael Fischer), and it works nicely for me. 
>> That gives me up to 512 Kbytes for the GUI, which is a lot!!
>>
>> Hope it helps. If you have any further question, don't hesitate 
>> asking! I am not an expert but that is what I am doing.
>>
>> If you want an example I could send you some code, although a bit 
>> messy (but working).
>>
>> Regards
>> José
>>
>> Tim Tait wrote:
>>
>>>
>>> Has anbody done anything with serving dynamic data charts from 
>>> ethernut? I want to to display simple line graph of sensor readings 
>>> over time. I am thinking that a java applet is the way to go. Most of 
>>> the applets out there seem to big, one "tChart" seems reasonable at 
>>> 17kb, put you have to pay to get source. Is there another way?
>>>
>>> Thanks-
>>>
>>> Tim
>>>
> 
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