I want to show green/red circle on sample asp.net web forms web page depending on what arduino ethernet says
How can I approach this in code, some examples would be great, like how in asp send command, more important when to send, on button press or on user page load, timer, .... ? The simpler the better, just webforms web page that shows circle green/red depending on status of arduino, arduino doing other things - it just needs to reply for status to web forms page
update
found what I need
querystring that takes POST from arduino + Application state, it's like a variable that's stay constant to all users who view page
Put a web server on the Arduino that implements a simple web service returning the state information, and merge that data into your page.
You can either do this server-side (the main webapp executes a web service call to the Arduino while it is generating the page) or client-side (the client uses AJAX technologies to retrieve the data and render it).
I'd prefer to do it server side other things being equal, as this makes it possible to apply rate limiting, caching, authentication protection etc.
If the Arduino is connected by USB to the main web server then you could simplify the solution by having the status data transferred by USB rather than via a web service.