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AxonFramework / AxonFramework

Framework for Evolutionary Message-Driven Microservices on the JVM
https://axoniq.io/
Apache License 2.0
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Revise Event Store logic #3101

Open smcvb opened 2 months ago

smcvb commented 2 months ago

Enhancement Description

We should adjust the EventStore and EventStorageEngine to be in line with the new Unit of Work, ProcessingContext, and MessageStream API (as introduced in #2953). This would mean the EventStore would become more "async native," allowing a broader set of options when implementing (for us) and utilizing (for us and users) it.

Furthermore, as we've partially done for the CommandBus in PR #3003, we should layer the EventStore and EventStorageEngine into their separate concerns. By doing so, we increase the modularity and, through that, enhance the flexibility and testability of the separate layers. This change can go together with an adjusted and dedicated configuration API for event storage. If the scope of the PR increases too much, it would be fair to perform the configuration task in a separate PR.

Lastly, it is paramount we start revamping the APIs to support the dynamic consistency boundary (DCB) that'll come to Axon Server. With this in place on the EventStore level, we would greatly enhance Axon Framework's capabilities to event source different styles of models.

The stateful message handlers and saga revisioning issues are just two examples for which this support is mandatory.

Current Behaviour

The EventStore implementations use the old UnitOfWork and cover a lot of topics in a single class. Added, dynamic consistency boundary support is not included at all.

Wanted Behaviour

The EventStore implementations use the new async-native messaging API and are spread out over several layers. Lastly, the API should be ready to support the dynamic consistency boundary.

smcvb commented 1 month ago

Although snapshotting is a part of the original EventStore, the snapshotting logic will be implemented by another pull request than the base pull request for this issue.