Comet is the protocol you want. Which comet implementation is best is a more complex challenge.
If you're fine with Java (or, I suppose, Jython), or .NET (where IronPython is possible), I suspect (I havenโt tried them hard!) That the stream hub should be the main rival. This is a typical freemium product - you can get a free version ("like a free beer" ;-), or you can try the expensive Web Edition or even the more expensive Enterprise Edition; comparison of functions here (for example, free version: no https, no more than 10 simultaneous users, no .NET).
Alex martelli
source share