I need a help. how to make a web application for controlling other side automation via client PC? For simplified to explain: there is a webpage has light on/off button then other side computer on/off a lamp via parallel port?. Thanks for all comments..

 

You need a web server with a scripting language on the server (the computer with the lamp). You would write a web page with buttons for on/off. The page would "get" or "post" the results back to the web server, where a processing page would contain a script to turn the lamp on or off.

You will also need some sort of hardware interface software that you can call from the script, as web scripting languages don't generally talk directly to hardware ports. This would be some sort of small program (or programs) that would manipulate the parallel port when called by the script.

By far the most popular web server and scripting language combination is Apache and PHP. Python and Perl are other possibilities. Describing how to do this in detail would require a book, not a letter. I would therefore suggest that you try a bookstore for books on Apache and PHP.