Joselct.Communication.RabbitMQ 1.0.8

Joselct.Communication.RabbitMQ

RabbitMQ transport implementation for Joselct.Communication.Contracts.
Supports .NET publishers and consumers with OpenTelemetry tracing, metrics, and dead letter queue handling.

Quick start

1. Register in Program.cs

builder.Services.AddRabbitMq(builder.Configuration);

// Register one consumer per queue
builder.Services.AddRabbitMqConsumer<OrderCreatedMessage, OrderCreatedHandler>(
    queueName: "orders.created",
    exchangeName: "orders-exchange",
    declareQueue: true);

// OpenTelemetry (optional)
builder.Services.AddOpenTelemetry()
    .AddRabbitMqInstrumentation();

2. Publish a message

public class OrderService(IExternalPublisher publisher)
{
    public async Task CreateOrderAsync(Order order, CancellationToken ct)
    {
        // ... business logic ...

        await publisher.PublishAsync(new OrderCreatedMessage
        {
            OrderId = order.Id,
            Source = "orders-service"
        }, ct: ct);
    }
}

3. Handle a message

public class OrderCreatedHandler : IIntegrationMessageConsumer<OrderCreatedMessage>
{
    public async Task HandleAsync(OrderCreatedMessage message, CancellationToken ct)
    {
        // Your business logic here
    }
}

Configuration (appsettings.json)

{
  "RabbitMQ": {
    "Host": "rabbitmq",
    "Port": 5672,
    "UserName": "guest",
    "Password": "guest",
    "VirtualHost": "/",
    "UseSsl": false,
    "ReconnectDelaySeconds": 5,
    "MaxReconnectAttempts": 0,
    "MaxRetryCount": 3,
    "DeadLetterExchange": "dlx"
  }
}

Retry & Dead Letter Queue

When a handler throws an unhandled exception:

1. The message is requeued up to MaxRetryCount times.
2. On the final failure, a BasicNack with requeue: false is sent.
3. If the queue has x-dead-letter-exchange configured (set via DeadLetterExchange option), RabbitMQ automatically routes the message to the DLQ.

The retry count is read from the standard x-death header that RabbitMQ populates automatically — no custom header management is required.

Recommended RabbitMQ setup:

Exchange: dlx   (type: direct or fanout, durable: true)
Queue:    dlq   (bound to dlx)

Interoperability

Tracing headers (traceparent, tracestate) are injected and read as plain strings (W3C TraceContext standard). This ensures compatibility with consumers in Python, Go, Java, and other languages without any additional decoding.

The consumer also falls back to reading byte[] headers for backwards compatibility with older publisher versions.

Metrics (OpenTelemetry)