Azure Service Bus - Keep message in subscription once completed

Question

I want to keep messages in Service Bus Topic/Subscription for 30 days once it is completed, but make sure that the subscriber will not read it twice.

Here is the Azure function i created to perform it.

public class MyFunction
{
   private readonly ILogger<MyFunction> _logger;

   public MyFunction(ILogger<MyFunction> logger)
   {
    _logger = logger;
   }

[Function(nameof(MyFunction))]
public async Task Run([ServiceBusTrigger("%TopicName%", "%SubscriptionName%", Connection = "ServiceBus.ConnectionString")] string message)
{
    try
    {
       _logger.LogInformation("Started !");
       JObject JsonObject = JObject.Parse(message);
    }
    catch (Exception ex)
    {
        throw;
    }
  }
}

The issue is that once the function above complete its execution, the message disappear from the Service Bus subscription.

Any idea ?

Answer 1

I want to keep messages in Service Bus Topic/Subscription for 30 days once it is completed, but make sure that the subscriber will not read it twice.

That's not how Azure Service Bus works. It's not a database. Once a message is successfully processed, it will be removed from the queue. If it consistently fails, it will be dead-lettered.

What you need is an auditing feature. Then, you can have successfully processed messages audited and retained for whatever period that you need to. You could either use a middleware that would do it for you (MessageHanlder, NServiceBus, MassTransit, Wolverine, etc.) or build it*.

* not trivial and will require the ability to settle messages, which is currently being worked on for the Functions Isolated Worker SDK.