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persistence-service.md

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Centralized persistence service

The implemented solution exposes an HTTP service dedicated to storing and recovering the state of Eventflow.

Endpoints

  • Get /State /{key}: obtains the state associated with Key.
  • Put /State /{Key}: Create or replace the State.
  • Delete /State /{Key}: Eliminates the State.
  • Post /locks /{key} and delete /locks /{key}: Lock administration.

ETAG and concurrence control

Each response Updates must send if-mmetch with the eTag received. If it does not coincide, the service returns 412 precondition failed to avoid overwhelming.

Locks

Optimistic and pessimistic locks are offered. Customers can request an explicit lock on a key to long -term operations. Locks automatically expire to prevent permanent blockages.

Write-Ahead Log (Wal)

All mutations are recorded in a Wal. In case of failure, the service can reproduce tickets to restore the State. The Wal also serves as a source for replication.

Events

When the State changes, the service publishes an state.updated event. This allows other Eventflow components to react to the modification and maintain materialized caches or views.
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