public async Task SubscribeUserCreationAsync(Func <User, Task <SubscriberClient.Reply> > feedHandler, CancellationToken stoppingToken)
{
_logger.LogInformation($"Initializing subscription for {_pubSubCredentials} using { _userCreationSubscription }");
SubscriberServiceApiClient subscriber = PubSubHelper.CreateSubscriber(_pubSubCredentials);
await SubscribeAsync(subscriber, _userCreationSubscription, feedHandler, stoppingToken);
}
public async Task <bool> CreateUserAsync(User user)
{
var publisher = PubSubHelper.CreatePublisher(_pubSubCredentials);
await PublishAsync(publisher, _userCreationTopic, user);
return(true);
}
private async Task SubscribeAsync <T>(SubscriberServiceApiClient subscriber, SubscriptionName subscription, Func <T, Task <SubscriberClient.Reply> > feedHandler, CancellationToken stoppingToken)
{
while (!stoppingToken.IsCancellationRequested)
{
/// The returnImmediately parameter allows the pull async function
/// to get a response even when the channel is empty.
/// You can set this to false so that the current context
/// waits for a message for a bounded amount of time
PullResponse response = await subscriber.PullAsync(
subscription,
returnImmediately : true,
maxMessages : 20
);
foreach (var receivedMessage in response.ReceivedMessages)
{
var mesId = receivedMessage.Message.MessageId;
var message = receivedMessage.Message;
_logger.LogDebug($"Message received: {message.Data.ToStringUtf8()}");
try
{
/// The extraction process assumes that the best practice of
/// wrapping PubSub data in base64 encoding, thus it goes through
/// the process of decoding before finally parsing it as a C# object
/// This can be disabled by setting the base64decode parameter to false
/// e.g. PubSubHelper.Extract<T>(message, false)
var extracted = PubSubHelper.Extract <T>(message);
var subscriptionResult = await feedHandler(extracted);
if (subscriptionResult == SubscriberClient.Reply.Ack)
{
await subscriber.AcknowledgeAsync(subscription, new[] { receivedMessage.AckId });
}
}
catch (Exception exc)
{
_logger.LogError($"Error in subscription {subscription.SubscriptionId}\n {exc.Message}\n {exc.StackTrace}");
}
}
// Add 10s delay per pull
await Task.Delay(1000);
}
}
private Task <PublishResponse> PublishAsync <T>(PublisherServiceApiClient publisher, TopicName topic, T obj)
{
var message = PubSubHelper.CreateMessage(obj);
return(publisher.PublishAsync(topic, new[] { message }));
}
