FIFO Queues

Amazon SQS FIFO queues guarantee that messages are processed exactly once, in the exact order they are sent. Wolverine has built-in support for SQS FIFO queues.

Naming Convention

Wolverine detects FIFO queues by the .fifo suffix on the queue name — this follows the AWS naming requirement. Simply use a queue name ending in .fifo when configuring your endpoints:

using var host = await Host.CreateDefaultBuilder()
    .UseWolverine(opts =>
    {
        opts.UseAmazonSqsTransportLocally()
            .AutoProvision();

        opts.PublishMessage<OrderPlaced>()
            .ToSqsQueue("orders.fifo")
            .ConfigureQueueCreation(request =>
            {
                // Required for FIFO queues
                request.Attributes[QueueAttributeName.FifoQueue] = "true";

                // Enable content-based deduplication so you don't have to
                // supply a DeduplicationId on every message
                request.Attributes[QueueAttributeName.ContentBasedDeduplication] = "true";
            });

        opts.ListenToSqsQueue("orders.fifo", queue =>
        {
            queue.Configuration.Attributes[QueueAttributeName.FifoQueue] = "true";
            queue.Configuration.Attributes[QueueAttributeName.ContentBasedDeduplication] = "true";
        });
    }).StartAsync();

Message Group Id and Deduplication Id

SQS FIFO queues use a Message Group Id to determine ordering — messages within the same group are delivered in order. Optionally, a Message Deduplication Id prevents duplicate delivery within a 5-minute window.

When Wolverine sends messages to a FIFO queue, it automatically maps:

• Envelope.GroupId → SQS MessageGroupId
• Envelope.DeduplicationId → SQS MessageDeduplicationId

You can set these values using DeliveryOptions when publishing:

await messageBus.PublishAsync(new OrderPlaced(orderId), new DeliveryOptions
{
    GroupId = orderId.ToString(),
    DeduplicationId = $"order-placed-{orderId}"
});

If you enable ContentBasedDeduplication on the queue (as shown above), you can omit the DeduplicationId and SQS will generate one based on the message body.

Dead Letter Queues for FIFO

When using dead letter queues with FIFO queues, the dead letter queue must also be a FIFO queue. Make sure to name it with a .fifo suffix:

opts.ListenToSqsQueue("orders.fifo", queue =>
{
    queue.Configuration.Attributes[QueueAttributeName.FifoQueue] = "true";
    queue.Configuration.Attributes[QueueAttributeName.ContentBasedDeduplication] = "true";
}).ConfigureDeadLetterQueue("orders-errors.fifo", dlq =>
{
    dlq.Attributes[QueueAttributeName.FifoQueue] = "true";
    dlq.Attributes[QueueAttributeName.ContentBasedDeduplication] = "true";
});

Partitioned Publishing with FIFO Queues

For high-throughput scenarios where you need ordered processing per group but want parallelism across groups, consider using Wolverine's partitioned sequential messaging with sharded SQS FIFO queues. This distributes messages across multiple queues based on their group id, giving you the best of both worlds — strict ordering within a group and horizontal scaling across groups.