Cross-browser real-time logic with Socket.IO

Older browsers don't support WebSockets. In order to provide a similar experience in these browsers, we have to use techniques such as long polling, using the Flash plugin sockets, or proprietary browser-specific options such as ActiveX in Internet Explorer.

Naturally, this is a mine field, requiring hours of browser testing and in some cases highly specific knowledge of proprietary protocols (for example, IE's Active X htmlfile object).

Socket.IO (via the engine.io module) provides a WebSocket-like API to the server and client to create the best-case real-time experience across a wide variety of browsers, including old (IE 5.5+) and mobile (iOS Safari and Android) browsers.

Note

The engine.io module has been logically extracted and refactored out from Socket.IO Version 0.9. The engine.io module is different in its approach; it uses enhancement instead of degradation. In the original socket.io, connections would fallback to the best available method...