The transactional outbox pattern leverages database transactions to update a microservice's state and an outbox table. Events in the outbox will be sent to an external messaging platform such as Apache Kafka. This technique is used to overcome the dual-write problem which occurs when you have to write data to two separate systems such as a database and Apache Kafka. The database transactions can be used to ensure atomic writes between the two tables. From there, a separate process can consume the outbox and update the external system as required.