public Task StartAsync(CancellationToken cancellationToken)
{
_executingTask = Task.Factory.StartNew(async() =>
{
using (var consumer = _consumerFactory.Create())
{
const string topic = "build.workshop.something";
consumer.Subscribe(topic);
Console.WriteLine($"KafkaConsumer started. Listening to topic: {topic}");
// Consume loop
while (!_cancellationTokenSource.IsCancellationRequested)
{
ConsumeResult <string, string> msg;
try
{
msg = consumer.Consume(cancellationToken);
using (var scope = _serviceProvider.CreateScope())
{
var message = MessagingHelper.MessageEnvelopeToMessage(msg.Value);
var eventType = _eventRegistry.GetInstanceTypeFor(message.EventName);
dynamic eventInstance = Activator.CreateInstance(eventType, message);
dynamic handlersList = _eventHandlerFactory.GetEventHandlersFor(eventInstance, scope);
foreach (var handler in handlersList)
{
await handler.HandleAsync(eventInstance);
}
}
}
catch (Exception ex)
{
Console.WriteLine($"Consumption of message failed, reason: {ex}");
continue;
}
try
{
await Task.Run(() => consumer.Commit(msg));
}
catch (Exception ex)
{
Console.WriteLine($"Error consuming message: Exception message: {ex.Message}. Raw message: '{msg.Value}'");
}
}
}
}, _cancellationTokenSource.Token,
TaskCreationOptions.LongRunning, TaskScheduler.Default)
.ContinueWith(task =>
{
if (task.IsFaulted)
{
Console.WriteLine("Event loop crashed");
}
}, cancellationToken);
return(Task.CompletedTask);
}
private async Task DoWork(CancellationToken stoppingToken)
{
const string topic = "build.workshop.something";
var newWorkshop = new WorkshopCreated
{
Id = Guid.NewGuid().ToString(),
Title = "Kafka - The basics",
Date = DateTime.Now.ToString("f")
};
using (var producer = _producerFactory.Create())
{
await producer.ProduceAsync(topic : topic, message : new Message <string, string>()
{
Key = Guid.NewGuid().ToString(),
Value = MessagingHelper.MessageToEnvelope(newWorkshop, "workshop_created", Guid.NewGuid().ToString())
});
}
}