Subject<bool> subjEvent = new Subject<bool>();
Subject<int> subjValue = new Subject<int>();

IScheduler sched = new EventLoopScheduler(ts => new Thread(ts));

subjEvent.ObserveOn(sched).Subscribe(
    r =>
        {
            if(r)
            {
                Console.WriteLine("Connected On: t{0}", Thread.CurrentThread.ManagedThreadId);

                subjValue.ObserveOn(sched).Subscribe(
                    x => Console.WriteLine("Recieved On: t{0}", Thread.CurrentThread.ManagedThreadId));
            }else{
                Console.WriteLine("Disconnect On: t{0}", Thread.CurrentThread.ManagedThreadId);
            }
        }
    );

subjEvent.OnNext(true);
for(int i=0; i< 10; i++)
{
    subjValue.OnNext(i);
}
subjEvent.OnNext(false);
subjValue.OnCompleted();
subjEvent.OnCompleted();

var query =
    from b in subjEvent.Do(x =>
        Console.WriteLine("{0}onnected On: t{1}",
            x ? "C" : "Disc",
            Thread.CurrentThread.ManagedThreadId))
    select b ? subjValue : Observable.Empty<int>();

query.Switch().Subscribe(x =>
    Console.WriteLine("Recieved On: t{0}",
        Thread.CurrentThread.ManagedThreadId));