e1eac82289
For now we have a single topic for all events. Since we use the eventname as the key for the kafka message, we have the property that they all get assigned to the same parition inside kafka and therefore are in-order. Alternatively one could have multiple topics. The code for the kafka connection is based on: https://github.com/confluentinc/confluent-kafka-dotnet/blob/master/examples/Web/KafkaClientHandle.cs
70 lines
3.0 KiB
C#
70 lines
3.0 KiB
C#
namespace EventBusKafka;
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public class EventBusKafka : IEventBus, IDisposable
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{
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// for now use single topic and event names as keys for messages
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// such that they always land in same partition and we have ordering guarantee
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// then the consumers have to ignore events they are not subscribed to
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// alternatively could have multiple topics (associated with event name)
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private readonly string _topicName = "eshop_event_bus";
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private readonly IKafkaPersistentConnection _persistentConnection;
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private readonly ILogger<EventBusKafka> _logger;
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private readonly IEventBusSubscriptionsManager _subsManager;
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private readonly int _retryCount;
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private const string INTEGRATION_EVENT_SUFFIX = "IntegrationEvent";
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// Object that will be registered as singleton to each service on startup,
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// which will be used to publish and subscribe to events.
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public EventBusKafka(IKafkaPersistentConnection persistentConnection,
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ILogger<EventBusKafka> logger, IEventBusSubscriptionsManager subsManager, int retryCount = 5)
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{
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_persistentConnection = persistentConnection ?? throw new ArgumentNullException(nameof(persistentConnection));
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_logger = logger ?? throw new ArgumentNullException(nameof(logger));
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_subsManager = subsManager ?? new InMemoryEventBusSubscriptionsManager();
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_retryCount = retryCount;
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}
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public void Publish(IntegrationEvent @event)
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{
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var eventName = @event.GetType().Name.Replace(INTEGRATION_EVENT_SUFFIX, "");
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var jsonMessage = JsonSerializer.Serialize(@event, @event.GetType());
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// map Integration event to kafka message
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// event name something like OrderPaymentSucceededIntegrationEvent
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var message = new Message<string, string> { Key = eventName, Value = jsonMessage };
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IProducer<string, string> kafkaHandle =
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new DependentProducerBuilder<string, string>(_persistentConnection.Handle).Build();
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kafkaHandle.ProduceAsync(_topicName, message);
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}
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public void Subscribe<T, TH>() where T : IntegrationEvent where TH : IIntegrationEventHandler<T>
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{
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throw new NotImplementedException();
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}
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public void SubscribeDynamic<TH>(string eventName) where TH : IDynamicIntegrationEventHandler
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{
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throw new NotImplementedException();
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}
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// Taken directly from rabbitMQ implementation
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public void UnsubscribeDynamic<TH>(string eventName) where TH : IDynamicIntegrationEventHandler
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{
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_subsManager.RemoveDynamicSubscription<TH>(eventName);
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}
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// Taken directly from rabbitMQ implementation
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public void Unsubscribe<T, TH>() where T : IntegrationEvent where TH : IIntegrationEventHandler<T>
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{
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var eventName = _subsManager.GetEventKey<T>();
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_logger.LogInformation("Unsubscribing from event {EventName}", eventName);
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_subsManager.RemoveSubscription<T, TH>();
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}
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public void Dispose()
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{
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_subsManager.Clear();
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}
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} |