Question

If I have a saga that consists of two message types, say started by message1 and completed by message2, can I return a callback if a message2 comes in without a message1 already existing? I know it will dump it in the error queue, but I want to be able to return a status to the sending client to say there is an error state due to the first message not being there.

Answer 1

So I figured it out, I just needed to implement IFindSagas for the message type:

public class MySagaFinder : IFindSagas<MySagaData>.Using<Message2>
{
    public ISagaPersister Persister { get; set; }
    public IBus Bus { get; set; }

    public MySagaFinder FindBy(Message2 message)
    {
        var data = Persister.Get<MySagaData>("MessageIdProperty", message.MessageIdProperty);
        if (data == null)
        {
            Bus.Return(0);
        }
        return data;
    }
}

I don’t know if this is the right way to do it, but it works!