Command ID / Message ID

[paneq]

Yo, in relation to #346 #362

I wanted to achieve common API for getting command ID's and event ID's.

• Right now for event's the API is event_id.

• command_bus does not impose any structure on commands right now

• event_id does not sound like a good API for command ID's that could be used by #correlate_with() which currently looks like:

  def correlate_with(other_message)
      self.correlation_id = other_message.correlation_id || other_message.event_id
      self.causation_id   = other_message.event_id
  end

I think both (events and commands) are messages so it feels natural for me to assume message_id as the common interface. That would mean adding message_id reader to RubyEventStore::Event and changing the code correlate_with code to:

def correlate_with(other_message)
   self.correlation_id = other_message.correlation_id || other_message.message_id
   self.causation_id   = other_message.message_id
end

Does that make sense in your opinion?

For commands we are still not going to enforce/assume any schema or class etc. But if they follow the message_id interface, they could be used as an argument to correlate_with:

event.correlate_with(command)

[joelvh]

@paneq I think the message_id makes sense. Do you see some more 1st class Command existing in RES at some point?

[joelvh]

I would also potentially push for message_id being the actual value and event_id being an alias... but I know that is a much bigger change.

[paneq]

Do you see some more 1st class Command existing in RES at some point?

At some point probably, but I don't have a vision for it yet.

I would also potentially push for message_id being the actual value and event_id being an alias... but I know that is a much bigger change.

Well, we could maintain both getters and setters...