gistfile1.cs

    public class LocationSubscriber : IObserver<Location>
    {
        private IDisposable unsubscriber;
        private string instName;

        public LocationSubscriber(string name)
        {
            this.instName = name;
        }

        public string Name { get { return this.instName; } }

        public virtual void Subscribe(IObservable<Location> provider)
        {
            if (provider != null)
                unsubscriber = provider.Subscribe(this);
        }

        public virtual void OnCompleted()
        {
            Console.WriteLine("The Location Tracker has completed transmitting datat to {0}", this.Name);
            this.Unsubscribe();
        }

        public virtual void OnError(Exception ex)
        {
            Console.WriteLine("{0} location cannot be determined.", this.Name);
        }

        public virtual void OnNext(Location value)
        {
            Console.WriteLine("{2}: the current location is {0}, {1}", value.Latitude, value.Longitude, this.Name);
        }

        public virtual void Unsubscribe()
        {
            unsubscriber.Dispose();
        }
    }