okapi

A Kotlin library implementing the transactional outbox pattern — the canonical solution for “publish a message AND commit a database transaction atomically without distributed transactions”. Apache 2.0, published under the SoftwareMill OSS umbrella.

Why outbox matters

• Domain events shipped via Kafka or HTTP webhooks MUST not get lost when the publishing transaction commits but the transport call fails (or vice versa).
• Outbox writes the event to a database table inside the same transaction, then a separate worker drains the table to the broker — all-or-nothing semantics, no 2PC.
• okapi delivers to Kafka or HTTP webhooks, backed by PostgreSQL or MySQL, with Spring Boot autoconfiguration out of the box.