public void Init()
{
//checkpoint token, can be persisted so we don't need to read the EventStore from scratch
string checkpointToken = null;
var pollingClient = new PollingClient(Program.StoreEvents.Advanced);
_observer = pollingClient.ObserveFromBucket(InvoicesBucketId, checkpointToken);
_observer.Subscribe(new InvoicesObserver());
//init the projection on startup
_observer.PollNow();
//start a long running task that will poll the event store periodicaly
_observerTask = _observer.Start();
}