Opera was the last major browser to add support for handling cross-origin requests in its 12th version. The CORS protocol was devised several years ago by a W3C working group to allow for clean making of cross-domain XHR, without JSONp hacks. CORS was initially adopted by Firefox and Chrome, and was subsequently joined by the other major players, such as Microsoft’s Internet Explorer.
Today more than 85% of the browsers on the web support CORS and an increasing number of developers are starting to use the protocol, judging by downloads of our CORS Filter package which allows CORS support to be easily retrofitted to any Java web app or service. When the new Opera 12 appeared the CORS Filter was successfully tested under it.
Thanks to Joost Cassee the CORS filter is now also available on Maven.