I have a feature I’m attempting to implement using NServiceBus but not sure the pattern to use here. (I’m fairly new to NServiceBus)
I’ll try to explain where my uncertainty comes from:
User interaction triggers MVC controller to send a command to perform a domain operation. This command raises an event to notify others that this occurred.
A handler that subscribes to this event determines whether or not another domain operation should occur.
This is where I’m unclear as to the proper pattern to follow. At this point should the event handler:
- just make the changes required?
- send a new command to do it? If so, send it back to the originating service/process?
- another option?
Part of me is wondering if I should be using an in-proc domain event to handle this, but I don’t think the first command should have to wait on the second one before it returns. In fact it could happen much later. That is why I went the route of using the bus to handle it async. Also, an email will need to be generated once the second operation finishes. Should that be triggered from yet another event/command?
Any and all guidance appreciated.
If there is no need to wait for the second action then yes, it should be done asynchronously so the processing of the first command should publish an NServiceBus event. The handler for that event would (likely) be hosted in a separate endpoint which would then just do the work – no need to send another command there.