System.InvalidOperationException: 'Local transactions cannot span multiple entities or partitions.

I’m trying to use the “send via” feature to be able to send messages to more than one entity inside a transaction.

I have the following entities:

• Topic: mytesttopic, which has one subscription: input_subscription
• Topic: output_1
• Topic: output_2
• Queue: transferqueue

I’m trying to receive sessions from input_subscription and for each received message:

1. Send a new message to output_1 (via transferqueue)
2. Send another message to output_2 (via transferqueue)
3. Complete the received message

All within one transaction, meaning, if the transaction doesn’t complete, then the received message should be restored in the input_subscription and no messages should have been send.

Visually:

                                                 ┌⟶ output_1
input_subscription ⟶ Handler ⟶ transferqueue ─┤
                                                 └⟶ output_2

This is the code:

var incomingSubscriptionClient = new SubscriptionClient(connection, "mytesttopic", "input_subscription", ReceiveMode.PeekLock, new NoRetry());
var output1sender = new MessageSender(connection, "output_1", "transferqueue");
var output2sender = new MessageSender(connection, "output_2", "transferqueue");

incomingSubscriptionClient.RegisterSessionHandler(async (receivedMessage, message, cancellation) =>
{
	using (var transaction = new TransactionScope(TransactionScopeAsyncFlowOption.Enabled))
	{
		await output1sender .SendAsync(new Message
		{
			Body = Encoding.UTF8.GetBytes("something"),
			SessionId = "mySessionId"
		});

		await output2sender .SendAsync(new Message
		{
			Body = Encoding.UTF8.GetBytes("something else"),
			SessionId = "mySessionId"
		});

		await session.CompleteAsync(receivedMessage.SystemProperties.LockToken);

		transaction.Complete();
	}
}, new SessionHandlerOptions(exception =>
{
	Console.WriteLine("session Receiver exception: " + exception.Exception.Message);
	return Task.CompletedTask;
}));

But I’m getting this exception when completing the received message:

System.InvalidOperationException: ‘Local transactions cannot span multiple entities or partitions.’

I’m not sure if this is a bug or if I’m doing something wrong.

[johnknoop]

@axisc Yes, that seems to work!! That’s awesome.

Thanks

[axisc]

there is some overhead because the service requires compute to accept messages on the transfer entity and then forward it to the actual destination. I’d recommend using it only when there is a need for cross entity transactions.