Comet Streaming drivers in JavaScript have been implemented in several ways, including XHR with CORS, XDR, and "Forever IFrames".

An IFrame is an inline frame within a web page which contains an inline document. The term 'Forever IFrame' is used to denote an inline frame which is implicitly declared as infinitely long. This property of such frames allow the server to continually populate it with data. As browsers render and execute scripts on a page incrementally, the pushed data can be manipulated by the client as it passes into the frame.

The Forever IFrame delivery mode is supported by Universal Messaging's JavaScript API and can be used in all browsers.

In addition to Streaming, WebSocket and LongPolling delivery modes are supported.

Please see the JavaScript API Documentation for Drivers for more details.