Enforce OCC and Retry Policy per Command Handling

[yordis]

Context

I came across a workflow in which we must guarantee that we never consume or release inventory.

I can try to make rules in the command handling around the quantity, but that is not enough; it requires that a given command handling enforce strong OCC with a very expected version (that is the default behavior today) or fail without retries around :wrong_expected_version failure, the client must decide if the OCC should be retry or not.

Also, this is a very similar situation to commanded/commanded#580 (comment) to some extent, where a user made a decision based on a given ETAG, which is not supported since I can not pass the expected version.

Without getting too much into solution space, which is not my intent here, ideally, I could do the following:

 dispatch ConsumeInventory,
    to: ConsumeInventoryHandler,
    aggregate: Inventory,
    identity: :inventory_id,
    retry: :disabled,
    expected_version: :exact_version # :any_version | :no_stream | :stream_exists | :exact_version

Such values would take (please correct me here) the above things that may be passed in the dispatch/2, primarily because Application developers may not be aware of such firm decisions critical to the business. So, dispatching the command would require a lot of care.

References

• Allow the aggregate's expected version to be included in command dispatch commanded#580