How can i come to know about internet connection

Hi frnds,
I have been develping a simple web application to retrieve the files stored in the google docs. when user comes and give his credentials first i need to check whether the internet connection is there or not if it is I have to continue with other options if not then I have to display a message that there is no internet connection.Am developing this application using php code please am requesting anybody help me to get how i can do this...

thank you
harry..

 

Using ajax to call back to your webserver and check the internet connection !!!

 

If it is a web app(php, ajax, ruby on rails), then most processing is done server side. There is no reason to check if the user has an internet connection, as the work is done by your web server.