Events & Data Model

The OutboxEvent record model, the OutboxKafkaEvent Avro schema, and how services publish through the outbox.

OutboxEvent (persisted model)

The abstract OutboxEvent model comes from arya-banking-common and is persisted in a Mongo collection per concrete entity (e.g., user_outbox in user-service):

Field	Description
`id`	Record identifier
`aggregateId`	Business aggregate the event belongs to — also the Kafka message key
`eventType`	Logical event type (e.g., `USER_INSERT`)
`payload`	Event payload
`topic`	Target Kafka topic, stored per event on the record
`outboxStatus`	`OutboxStatus` enum: `PENDING`, `COMPLETED`, `FAILED`, `RETRY_PENDING`
`retryCount`	Number of publish attempts so far

OutboxKafkaEvent (Avro schema)

The Avro message published to Kafka, defined in org.arya.banking.common.avro:

Field	Type
`aggregateId`	`string`
`eventType`	`string`
`payload`	`string`

Publishing Flow

The outbox record is written inside the same @Transactional method as the business write, so both commit or roll back together:

> Java code-highlight

@Transactional
public void createUser(User user) {
    mongoTemplate.save(user);

    UserOutboxEvent outboxEvent = UserOutboxEvent.builder()
        .aggregateId(user.getId())
        .eventType("USER_INSERT")
        .topic("arya-user-svc-usr-update")
        .payload(serialize(user))
        .outboxStatus(OutboxStatus.PENDING)
        .retryCount(0)
        .build();

    userOutboxRepository.save(outboxEvent);
}

Concrete Repository

Services provide a concrete repository interface that narrows the generic contract to their entity:

> Java code-highlight

public interface UserOutboxRepository extends OutboxEventRepository<UserOutboxEvent> {
}

The topic is stored per-event on the outbox record (event.getTopic()) — it is not a fixed constant. Current usage: user-service publishes eventType USER_INSERT to topic arya-user-svc-usr-update.

Configuration

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