BrokerObserver

As for the PropertyObserver or the MementoObserver the BrokerObserver is an easy shortcut to react to message arrivals when using the message broker.

var monitor = BrokerObserver.Using(aBrokerInstance)
    .WaitingFor<MySampleMessage>();

We can use a monitor to trigger, for example, the CanExecuteChanged event of a ICommand interface implementation:

var monitor = BrokerObserver.Using(aBrokerInstance)
    .WaitingFor<MySampleMessage>();

DelegateCommand.Create()
    .OnCanExecute(state =>
    {
        //evaluate if the command can be executed.
        return true;
    })
    .OnExecute(state =>
    {
        //execute the command
    })
    .AddMonitor(monitor);

What the above code does is to trigger the CanExecuteChanged logic each time a message of type MySampleMessage is delivered via the monitored message broker.