Quick and dirty way to hook up RX to an Event Store subscription. Emphasis on "quick" and "dirty".

EventStoreConnectionExtensions.cs

static class EventStoreConnectionExtensions
{
    public static Task<EventStoreRxSubscription> SubscribeToAll(this EventStoreConnection connection, bool resolveLinkTos)
    {
        return Task<EventStoreRxSubscription>.Factory.StartNew(() => {
            var subject = new Subject<ResolvedEvent>();

            var subscriptionTask = connection.SubscribeToAll(resolveLinkTos, subject.OnNext, () => subject.OnError(new SubscriptionDroppedException()));
            subscriptionTask.Wait();

            return new EventStoreRxSubscription(subscriptionTask.Result, subject);
        });
    }
}

EventStoreRxSubscription.cs

internal class EventStoreRxSubscription
{
    public Subject<ResolvedEvent> Observable { get; private set; }
    public EventStoreSubscription Subscription { get; private set; }

    public EventStoreRxSubscription(EventStoreSubscription subscription, Subject<ResolvedEvent> observable)
    {
        Subscription = subscription;
        Observable = observable;
    }
}

SubscriptionDroppedException.cs

class SubscriptionDroppedException : Exception {}

Usage.cs

class Program
{
    static void Main(string[] args)
    {
        var connection = EventStoreConnection.Create(ConnectionSettings.Default);
        connection.Connect(new IPEndPoint(IPAddress.Loopback, 1113));

        var subscriptionTask = connection.SubscribeToAll(true);
        subscriptionTask.Wait();
        var subscription = subscriptionTask.Result;

        var observable =
            subscription.Observable.Where(x => x.OriginalEvent.EventType == "WoftamEvent").Delay(new TimeSpan(0, 0, 0, 5));
        observable.Subscribe(t => Console.WriteLine(t.OriginalStreamId));

        Console.ReadLine();
    }
}