Calling ASP.Net webservice from Javascript on Sharepoint

Hi,

I am calling a ASP.Net webservice from javascript. TheASP.net webservice is hosted on the same server as my Sharepoint site.My javascript code works fine when the web service is called from a stand alone html page, but i recieve "Access Denied" error when I upload the same html on Sharepoint.

I can invoke the same webservice succesfully using server side code in Sharepoint, but I want to use it on Sharepoint 2013 online hence cannot work with server side code.