Command dispatch with strong consistency guarantee #83
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Create `Subscriptions` module to track all event store subscriptions. Use ETS table to track subscriptions Add `consistency` option to event handlers, process managers, and command router. Create command dispatch middleware to enforce requested consistency guarantee. Extract aggregate identity from command moved to middleware.
Expire stale entries after one hour. Since the stream ack's are only used during command dispatch, their timeliness is very short lived (seconds - minutes).
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Add support for command dispatch that waits for all strongly consistent handlers (event handlers, process managers) to have successfully processed all events created by the command being dispatched.
Implementation
Created a
Subscriptionsmodule to track all event store subscriptions. It uses an ETS table to track subscriptions and streams/versions that have been handled per subscription.Added a
consistencyoption to event handlers, process managers, and command router. It supports either:eventual(default) or:strongconsistency.Consistency is guaranteed by a new command dispatch middleware that blocks after successful dispatch. Once you receive an
:okreply from a command dispatch you are guaranteed that the handlers have completed.Fixes #82.