This is a Dart client library for SockJS. SockJS gives you a coherent, cross-browser, Javascript API which creates a low latency, full duplex, cross-domain communication channel between the browser and the web server.
Under the hood SockJS tries to use native WebSockets first. If that fails it can use a variety of browser-specific transport protocols and presents them through WebSocket-like abstractions.
SockJS is intended to work for all modern browsers and in environments which don't support WebSocket protocol, for example behind restrictive corporate proxies.