Correlation and causation ids about commanded HOT 2 CLOSED

@fdbeirao No, I don't think so. Perhaps, yes! I need to read further into how correlation ids would work for process managers. In theory, it could be the case that a process manager is identified by the correlation id of the message (event) that created it.

In Commanded you would use a process manager to implement a saga. So I would say the identity returned from the process manager's interested?/1 function is the identity for the process manager (aka saga).

In the example below it is the transfer_uuid that uniquely identifies a single instance of the transfer money process manager:

defmodule TransferMoneyProcessManager do
  use Commanded.ProcessManagers.ProcessManager,
    name: "transfer_money_process_manager",
    router: BankRouter

  def interested?(%MoneyTransferRequested{transfer_uuid: transfer_uuid}), do: {:start, transfer_uuid}
  def interested?(%MoneyWithdrawn{transfer_uuid: transfer_uuid}), do: {:continue, transfer_uuid}
  def interested?(%MoneyDeposited{transfer_uuid: transfer_uuid}), do: {:stop, transfer_uuid}
  def interested?(_event), do: false

  # ...
end

from commanded.

Quick and maybe unrelated question. Do you see the correlationId as being semantically the same as a saga identifier, from Hector Garcia-Molina's paper "sagas":

The begin-saga command can return a saga identifier to the program. This identifier can then be passed to the system on subsequent calls made by the saga.

Or am I mixing up two concepts here?

from commanded.