For a more complete example, check out:
https://github.com/damienbod/SignalRMessagingErrorHandling
or
http://damienbod.wordpress.com/2013/11/20/signalr-a-complete-wpf-client-using-mvvm/
http://damienbod.wordpress.com/2013/11/12/signalr-messaging-a-more-complete-console-server/