/// <summary>
/// Subscribes to the observable using the given observer.
/// </summary>
/// <param name="observer">Observer to send the observable's data to.</param>
/// <param name="subscriptionUri">URI to identify the subscription.</param>
/// <param name="state">Additional metadata to associate with the artifact. Implementations can interpret this value, or ignore it.</param>
/// <returns>Subscription object that can be used to cancel the subscription, or an exception if the submission was unsuccessful.</returns>
public IReactiveSubscription Subscribe(IReactiveObserver <T> observer, Uri subscriptionUri, object state = null)
{
if (observer == null)
{
throw new ArgumentNullException(nameof(observer));
}
if (subscriptionUri == null)
{
throw new ArgumentNullException(nameof(subscriptionUri));
}
return(SubscribeCore(observer, subscriptionUri, state));
}
/// <summary>
/// Subscribes to the observable using the given observer.
/// </summary>
/// <param name="observer">Observer to send the observable's data to.</param>
/// <param name="subscriptionUri">URI to identify the subscription.</param>
/// <param name="state">Additional metadata to associate with the artifact. Implementations can interpret this value, or ignore it.</param>
/// <returns>A subscription object that can be used to cancel the subscription, or an exception if the submission was unsuccessful.</returns>
protected override IReactiveSubscription SubscribeCore(IReactiveObserver <T> observer, Uri subscriptionUri, object state)
{
if (observer is IExpressible expressible)
{
var qbserver = Provider.CreateQbserver <T>(expressible.Expression);
var qubscription = SubscribeCore(qbserver, subscriptionUri, state);
return(qubscription);
}
//
// NB: A sophisticated client could support this by creating a "reverse proxy" stream in the service and
// create a channel to ship events from the stream to the local observer instance. However, it does
// require more than this in order to deal with client disconnects and cleanup of service-side resources
// or support some form of client-side recovery to reassociate an observer instance to an existing
// query (given its subscription URI).
//
throw new NotSupportedException("Local observer cannot be subscribed to a remote observable.");
}
protected override IReactiveSubscription SubscribeCore(IReactiveObserver <T> observer, Uri subscriptionUri, object state)
{
return(SubscribeImpl(observer, subscriptionUri, state));
}
public IReactiveSubscription Subscribe(IReactiveObserver <T> observer, Uri subscriptionUri, object state)
{
throw new NotImplementedException();
}
/// <summary> /// Subscribes to the observable using the given observer. /// </summary> /// <param name="observer">Observer to send the observable's data to.</param> /// <param name="subscriptionUri">URI to identify the subscription.</param> /// <param name="state">Additional metadata to associate with the artifact. Implementations can interpret this value, or ignore it.</param> /// <returns>Subscription object that can be used to cancel the subscription, or an exception if the submission was unsuccessful.</returns> protected abstract IReactiveSubscription SubscribeCore(IReactiveObserver <T> observer, Uri subscriptionUri, object state);
