What is different between EventHub Client with EventHub Processor?

Question

I find there are two way to receive EventHub message data:

Using EventHub Processor, it seems will use checkpoint to save. It will make sure when the process running EventProcessor on a specific partition dies/crashes.

public class SimpleEventProcessor : IEventProcessor
{
    public Task CloseAsync(PartitionContext context, CloseReason reason)
    {
       Console.WriteLine($"Processor Shutting Down. Partition '{context.PartitionId}', Reason: '{reason}'.");
       return Task.CompletedTask;
    }

    public Task OpenAsync(PartitionContext context)
    {
       Console.WriteLine($"SimpleEventProcessor initialized. Partition: '{context.PartitionId}'");
       return Task.CompletedTask;
     }

    public Task ProcessErrorAsync(PartitionContext context, Exception error)
    {
       Console.WriteLine($"Error on Partition: {context.PartitionId}, Error: {error.Message}");
       return Task.CompletedTask;
    }

    public Task ProcessEventsAsync(PartitionContext context, IEnumerable<EventData> messages)
    {
       foreach (var eventData in messages)
       {
          var data = Encoding.UTF8.GetString(eventData.Body.Array, eventData.Body.Offset, eventData.Body.Count);
             Console.WriteLine($"Message received. Partition: '{context.PartitionId}', Data: '{data}'");
       }
       return context.CheckpointAsync();
    }
}

Using EventHub client to receive message:

EventHubClient eventHub
var reciever = eventHub.CreateReceiver("consumer1", "0", EventPosition.FromStart());
var recieved = await reciever.ReceiveAsync(10);

What is the difference for them? Could we save the checkpoint for second ways? How to handle the crash case in second ways? Why does it need two different ways?

score 0 · Answer 1 · answered Dec 24 '19 at 16:44

EventHubClient aka. low level API is used for building connectors. In this case, developer is responsible to manage partition receivers, checkpoints, load distribution, and crash recovery etc. Most won't be using this API to receive, and again this API is for building source to sink connectors.

Processor Host comes with built-in checkpointing, load distribution, and partition receiver manager. This API might look like an overkill when it comes to implement IEventProcessor, and provide storage checkpoint store however in the long run it is more worry-free.

What is different between EventHub Client with EventHub Processor?

1 Answers1