How to Turn On An LED via Wireless Network

Projects General Guidance
1

At the absolute highest level, I want to be able to click a button on my computer and an LED turns on somewhere else.
Breaking down the problem, one approach might be to have a server that controls a com port using php and then a client computer might load a webform.
Any other feasible methods?

For my idea, I haven't a clue where to start with the php script. Can anyone link me to external libraries I can just download (and not sign up for anything) with good API documentations?
Or does php itself provide an API?

2

012anonymousxyz:
an LED turns on somewhere else.

Where is the 'somewhere else'? Is there an Arduino there? How is it connected to 'my computer'?

3

There are two computers that are both connected to a network. To one of the computers there is an Arduino connected via USB cable.
That is all we are working with.

As for which is client and server, I outlined how I thought it might work above. And here is one thing I want to avoid: I don't want to have to reload the page each time I click the button if at all possible. I just want to click a button or press a key, and the LED will reverse states.
If the page MUST be reloaded, I'm okay with it, but I really want to avoid that.

Any ideas?

4

I'd go for Firmata for the Arduino side code and the interface to it.

You can control that (and other things) from a Processing front end, and you can run Processing within a web browser.

In other words, you can probably achieve this without needing to write any code.