If you are using SignalR 1.0.0 (which you should since it is now officially released), you need to change your call to MapHubs
to enable cross-domain requests. This is assuming your website is not being served from localhost:9000. I'm guessing it isn't since you are passing in the url to $.hubConnection
.
app.MapHubs(new HubConfiguration { EnableCrossDomain = true });
Before the final release of 1.0.0, CORS was enabled by default.