Spring Integration with Java DSL support to send and process "Work Units" with a RabbitMQ broker mediating the transfer

Steps

• Start RabbitMQ server:

rabbitmq-server

• Start the Work Handler:

cd work-handler
mvn spring-boot:run

• Start the Work Dispatcher:

cd work-dispatcher
mvn spring-boot:run

• Create dummy work units by calling a controller endpoint:

http://localhost:8080/generateWork?id=1&definition=test&throw_exception=false

• A throw exception flag will cause the "Work Unit" processor to throw an error. If that happens a complex flow is kicked off -

  • There is a Dead Letter exchange configured for the Work unit queue, the message from the dead letter exchange is routed to the Dead letter queue, dead letter queue has a ttl of 20 seconds and in-turn has the dead letter exchange configured to be the work units queue thus creating a nice cycle. The cycle of consuming messages is broken by adding in a filter in the processing flow to break processing after a set number of retries - 3 in this case.