Outbox pattern with Spring Integration

Question

We want to implement an Outbox pattern by using spring integration. Starting from this example, we came up with this simpeler solution:

protected IntegrationFlowDefinition<?> buildFlow() {
    return from("domain.event.sender")
            .channel(c -> c.queue(this.jdbcMessageStore, "outbox"))
            .handle(
                    this.messagePublisherHandler,
                    c -> c.poller(poller -> poller.fixedDelay(1000).transactional()));
}

This solution will take a message from "domain.event.sender", store it in the database (in case of an error) and then POLL this db to send a message to a MessageBus (via messagePublisherHandler).

We want to have a solution that will ALSO process this message immediately after transaction synchronisation, without that we have to wait for the poller to finish.

Answer 1

It was a stupid answer. I just needed to change the fixedDelay to 0:

protected IntegrationFlowDefinition<?> buildFlow() {
    return from("domain.event.sender")
            .channel(c -> c.queue(this.jdbcMessageStore, "outbox"))
            .handle(
                    this.messagePublisherHandler,
                    c -> c.poller(poller -> poller.fixedDelay(0).transactional()));
}

Answer 2

It would be great if you show how you process a business data before sending it into this domain.event.sender channel for storing into so-called outbox table.

However it is just pretty simple to make this domain.event.sender as a PublishSubscribeChannel and have another subscriber which would do the logic you are asking. If you don't configure this channel for a TaskExecutor, both subscribers will process the same message sequentially and withing the same business transaction.

See more info in docs: https://docs.spring.io/spring-integration/reference/channel/implementations.html#channel-implementations-publishsubscribechannel