Azure Durable Function Fan Out Only

Question

I have a Web App with Azure Service Bus, Azure SQL and I wanted to use Azure Durable Function Fan Out to process the messages from Azure Service Bus which will contain JSON data from the Web App. I don't require the Fan In process as this aggregates the results of the Fan Out outputs. Can we use Azure Durable Function Fan Out without using Fan In?

My aim is to make the whole process scaleable to demand.

Answer 1

@Kman The Service Bus Trigger itself should be able to scale out to multiple workers as required without durable functions. This would be much simpler to have unless Durable Functions is required for other reasons.

To the actual question of whether it is possible, yes, that should work. You just don't have to await the returned Task.

But do note that internally this is like how a queue trigger works without the retry benefits, unless if you are using the CallActivityWithRetryAsync API which would not make it a fire-and-forget option. If this isn't a concern, then nothing to worry about. If so, you could consider is triggering a sub-orchestration instead which could implement retries as required.

Also, this approach would mean the original message would have to be completed irrespective of the outcome since the client function wouldn't wait. But you can defer the message instead (as explain in this SO post) and retrieve at the end if required.