public async Task Subscribe(Subscriber subscriber, MessageType messageType, ContextBag context)
{
//When the subscriber is running V6 and UseLegacyMessageDrivenSubscriptionMode is enabled at the subscriber the 'subcriber.Endpoint' value is null
var endpoint = subscriber.Endpoint ?? subscriber.TransportAddress.Split('@').First();
var subscriptionClient = new SubscriptionClient { TransportAddress = subscriber.TransportAddress, Endpoint = endpoint };
var attempts = 0;
//note: since we have a design that can run into concurrency exceptions we perform a few retries
// we should redesign this in the future to use a separate doc per subscriber and message type
do
{
try
{
using (var session = OpenAsyncSession())
{
var subscriptionDocId = Subscription.FormatId(messageType);
var subscription = await session.LoadAsync<Subscription>(subscriptionDocId).ConfigureAwait(false);
if (subscription == null)
{
subscription = new Subscription
{
Id = subscriptionDocId,
MessageType = messageType,
Subscribers = new List<SubscriptionClient>()
};
await session.StoreAsync(subscription).ConfigureAwait(false);
}
if (!subscription.Subscribers.Contains(subscriptionClient))
{
subscription.Subscribers.Add(subscriptionClient);
}
else
{
var savedSubscription = subscription.Subscribers.Single(s => s.Equals(subscriptionClient));
if (savedSubscription.Endpoint != subscriber.Endpoint)
{
savedSubscription.Endpoint = subscriber.Endpoint;
}
}
await session.SaveChangesAsync().ConfigureAwait(false);
}
return;
}
catch (ConcurrencyException)
{
attempts++;
}
} while (attempts < 5);
}
public async Task Unsubscribe(Subscriber subscriber, MessageType messageType, ContextBag context)
{
var subscriptionClient = new SubscriptionClient { TransportAddress = subscriber.TransportAddress, Endpoint = subscriber.Endpoint };
using (var session = OpenAsyncSession())
{
var subscriptionDocId = Subscription.FormatId(messageType);
var subscription = await session.LoadAsync<Subscription>(subscriptionDocId).ConfigureAwait(false);
if (subscription == null)
{
return;
}
if (subscription.Subscribers.Contains(subscriptionClient))
{
subscription.Subscribers.Remove(subscriptionClient);
}
await session.SaveChangesAsync().ConfigureAwait(false);
}
}
