design issue - embedded webserver application

Hi everybody,

I am having a question about a design of a system. My goal is to 
integrate a single board computer into a existing measurement system.
A webserver should run on the SBC so that the system can be configured 
with a browser. If it is possible it would be great if the website could 
display und update the measurement values without clicking refresh 
button etc.
The approach that i can think of:
1.) use of linux or windows ce and their built-in webservers
2.) programming of a application which controls the
     measurement system.
3.) using some interface-technology (cgi?) to connect the webserver
     with the control-application.
4.) using some scripts embedded in html which the webserver then parses
     and fills in the values which the control-application returned for
     example.

So far so bad :) As i am a newbie i would be glad about all comments
or suggestions about which technologies to use (cgi for interface? , php 
for scripts?, win ce with asp? or linux?,...) or about possible
designs for this problem. I have googled quite long but it hard to
find examples for such a application.

thanks for any help

axel maier

On Mar 23, 4:31=A0pm, Axel Maier <axel.maie...@web.de> wrote:
> Hi everybody,
>
> I am having a question about a design of a system. My goal is to
> integrate a single board computer into a existing measurement system.
> A webserver should run on the SBC so that the system can be configured
> with a browser. If it is possible it would be great if the website could
> display und update the measurement values without clicking refresh
> button etc.
> The approach that i can think of:
> 1.) use of linux or windows ce and their built-in webservers
> 2.) programming of a application which controls the
> =A0 =A0 =A0measurement system.
> 3.) using some interface-technology (cgi?) to connect the webserver
> =A0 =A0 =A0with the control-application.
> 4.) using some scripts embedded in html which the webserver then parses
> =A0 =A0 =A0and fills in the values which the control-application returned=
 for
> =A0 =A0 =A0example.
>
> So far so bad :) As i am a newbie i would be glad about all comments
> or suggestions about which technologies to use (cgi for interface? , php
> for scripts?, win ce with asp? or linux?,...) or about possible
> designs for this problem. I have googled quite long but it hard to
> find examples for such a application.


Well, if you can put an OS that has a webserver on the SBC, that's
certainly simplest.  OTOH, writing a basic web server is not all that
difficult either (particularly if you have a TCP/IP stack already),
but you're only going to have basic functions, and there will be a non-
trivial learning curve if you don't know what a web server really does
already.

CGI is only sort-of a technology.  The term gets used two ways.  First
as a general reference to any program (script, compiled, or whatever),
that the web server will invoke based on the contents of the HTLM
request it receives (usually based on the extension).  The more
traditional definition is of the original (and still used) process
where a web server does that by launching a new process to run that
program, and passing a handle to the stream (the old stdin/out thing)
and other data in environment variables.  Again, that's usually based
on the query string, and is a common way to generate dynamic, rather
than static pages.  You'll almost certainly want to do something like
that to actaully get the data out of your device and into the server
web page.  Alternatively some sort of server-side scripting can be
embedded in static pages, which can then call out to other code (this
is often done with PHP).  In any case, the exact details are up to the
web server.

A major part will be defining exactly how complex you need things to
be.  If you need only limited security, and have only a few dynamic
pages, then a simple solution will do.  If you have hundreds of pages,
animations, need SSL, etc., you really need a full function web
server.

It sounds like you don't have that much experience on the web side, it
would probably be a useful exercise for you to hack up a prototype on
whatever development environment you have available.  You'll be able
to do traditional CGI scripts, server side scripting, and many other
things under either Linux or Windows, if you want to play with ASP (in
its various flavors), you'll be limited to Windows.

Another possibility, especially if there will be a limited number of
instances of this device, is to leave the device fairly dumb, and put
the management web server on a "real" machine, and just send commands
and queries back to the device.  Although it sort of sounds like
that=92s what you=92re trying to do =96 hang a full fledged computer,
running a real OS, off the side of the existing device.  If that=92s the
case, and you can actually toss a copy of Linux or Windows on there,
do that =96 the development tools available for a =93real=94 web server are
so much better.

As for updating the display, there are a variety of methods, but the
simplest is to just throw a "refresh" meta tag into the served web
page - that will cause the browser to reload the page after the
specified interval.

On Tue, 23 Mar 2010, Axel Maier wrote:

> Date: Tue, 23 Mar 2010 22:31:07 +0100
> From: Axel Maier <axel.maier82@web.de>
> Newsgroups: comp.arch.embedded
> Subject: design issue - embedded webserver application
> 
> Hi everybody,
>
> I am having a question about a design of a system. My goal is to integrate a 
> single board computer into a existing measurement system.
> A webserver should run on the SBC so that the system can be configured with a 
> browser. If it is possible it would be great if the website could display und 
> update the measurement values without clicking refresh button etc.
> The approach that i can think of:
> 1.) use of linux or windows ce and their built-in webservers
> 2.) programming of a application which controls the
>    measurement system.
> 3.) using some interface-technology (cgi?) to connect the webserver
>    with the control-application.
> 4.) using some scripts embedded in html which the webserver then parses
>    and fills in the values which the control-application returned for
>    example.
>
> So far so bad :) As i am a newbie i would be glad about all comments
> or suggestions about which technologies to use (cgi for interface? , php for 
> scripts?, win ce with asp? or linux?,...) or about possible
> designs for this problem. I have googled quite long but it hard to
> find examples for such a application.
>
> thanks for any help
>
> axel maier
>


You might have a look at mongoose ...  I haven't used it, but LinuxJournal 
this month did a feature article on it.  AFAICT, it is an embedded, 
threaded web server framework which does the heavy lifting for you, and 
has a light footprint, and language bindings for C, Python, C#, Ruby and 
Lua ...  should be suitable for embedding ... providing you have an 
underlying OS ... (perhaps something like an AVR32 - NGW100??)

 	http://code.google.com/p/mongoose/

As indicated, I haven't tried it, but it does look interesting ...

Cheers,
Rob Sciuk

On Mar 23, 11:31=A0pm, Axel Maier <axel.maie...@web.de> wrote:
> Hi everybody,
>
> I am having a question about a design of a system. My goal is to
> integrate a single board computer into a existing measurement system.
> A webserver should run on the SBC so that the system can be configured
> with a browser. If it is possible it would be great if the website could
> display und update the measurement values without clicking refresh
> button etc.
> The approach that i can think of:
> 1.) use of linux or windows ce and their built-in webservers
> 2.) programming of a application which controls the
> =A0 =A0 =A0measurement system.
> 3.) using some interface-technology (cgi?) to connect the webserver
> =A0 =A0 =A0with the control-application.
> 4.) using some scripts embedded in html which the webserver then parses
> =A0 =A0 =A0and fills in the values which the control-application returned=
 for
> =A0 =A0 =A0example.
>
> So far so bad :) As i am a newbie i would be glad about all comments
> or suggestions about which technologies to use (cgi for interface? , php
> for scripts?, win ce with asp? or linux?,...) or about possible
> designs for this problem. I have googled quite long but it hard to
> find examples for such a application.
>
> thanks for any help
>
> axel maier

My approach was different (and is far from what "most" people are
doing).
I did all the work on the side of the embedded system, as if it
had a monitor, keyboard and mouse - only it did not, it fits into
an MPC5200B based SOC and gets accessed via RFB ( VNC ). There are
various vnc clients freely available ( realVNC being the best I have
tried so far).
At 100 MbpS , 16 bits per pixel, one won't know this is a remote
system. At 10 MbpS it is noticeable, but still quite usable, one
could work with it without swearing. Actually this is valid even much
below 10 (not sure how much, did it recently over the net to maintain
a customer system, must have been 2-3 MbpS or so). All this at 800 x
600
display size, at 1280 x 800 and 100 MbpS there was no noticeable
difference
to 800 x 600(just tried it a few times in that format).

http://tgi-sci.com/tgi/nmcatb.htm

Not really recommending this approach as it implies having a lot
readily available to build on (which I did have); but it is a
possibility.
I want to make all the DPS and stuff available some time this year
so one can just write his application, but I have to write some
description of the whole thing for users which will be pretty
bulky so I am not even starting it yet :-).

Dimiter

------------------------------------------------------

Dimiter Popoff               Transgalactic Instruments



http://www.tgi-sci.com

------------------------------------------------------

http://www.flickr.com/photos/didi_tgi/sets/72157600228621276/

Hi Axel,

Axel Maier wrote:
> I am having a question about a design of a system. My goal is to 
> integrate a single board computer into a existing measurement system.
> A webserver should run on the SBC so that the system can be configured 
> with a browser. If it is possible it would be great if the website could 
> display und update the measurement values without clicking refresh 
> button etc.
> The approach that i can think of:
> 1.) use of linux or windows ce and their built-in webservers
> 2.) programming of a application which controls the
>     measurement system.
> 3.) using some interface-technology (cgi?) to connect the webserver
>     with the control-application.
> 4.) using some scripts embedded in html which the webserver then parses
>     and fills in the values which the control-application returned for
>     example.
> 
> So far so bad :) As i am a newbie i would be glad about all comments
> or suggestions about which technologies to use (cgi for interface? , php 
> for scripts?, win ce with asp? or linux?,...) or about possible
> designs for this problem. I have googled quite long but it hard to
> find examples for such a application.

Why not push the complexity into the browser?  E.g.,
write a Java applet so the "remote" end just has to
serve up bytes (that the applet can interpret however
is appropriate)?

This simplifies the workload in the "device".

On Mar 23, 4:31=A0pm, Axel Maier <axel.maie...@web.de> wrote:
> Hi everybody,
>
> I am having a question about a design of a system. My goal is to
> integrate a single board computer into a existing measurement system.
> A webserver should run on the SBC so that the system can be configured
> with a browser. If it is possible it would be great if the website could
> display und update the measurement values without clicking refresh
> button etc.
> The approach that i can think of:
> 1.) use of linux or windows ce and their built-in webservers
> 2.) programming of a application which controls the
> =A0 =A0 =A0measurement system.
> 3.) using some interface-technology (cgi?) to connect the webserver
> =A0 =A0 =A0with the control-application.
> 4.) using some scripts embedded in html which the webserver then parses
> =A0 =A0 =A0and fills in the values which the control-application returned=
 for
> =A0 =A0 =A0example.
>
> So far so bad :) As i am a newbie i would be glad about all comments
> or suggestions about which technologies to use (cgi for interface? , php
> for scripts?, win ce with asp? or linux?,...) or about possible
> designs for this problem. I have googled quite long but it hard to
> find examples for such a application.
>
> thanks for any help
>
> axel maier

www.winsystems.com and certainly others will have hardware that is
offered with everything from boot only, to romdos, to linux to windows
CE or better. So lots of chances for w'ever gui/browser you want.

Carl

Am 23.03.10 22:31, schrieb Axel Maier:
Ok thanks :-) these are good suggestions, i will have a closer look and 
try them out.

thank you very much
axel maier