06 - Interservice Bus

Owned by Anastasia Alexov (Unlicensed)
Apr 29, 2022

Design Diagram

The Interservice Bus provides the means for the exchange of data in the decoupled architecture. RabbitMQ (https://www.rabbitmq.com/) is the open source message broker used. Through a direct exchange, RabbitMQ routes each message type to its own queue. Consumers then connect to the queue containing the messages they are designed to operate on.


Key Concept: Best Practices for ISB - Service interaction

Below is a list of practices to be implemented when interacting with the ISB:

  • Use separate connections for consumers and producers.
  • Set a logical prefetch count (often 1) that reflects the number of messages the service is allowed to work on at any one time.
  • Only "Acknowledge" a message after the work it has requested is accomplished. In other words, if something fails mid-process, you want the message to be re-queued and tried again.
  • Only "Reject" messages if they are intrinsically un-processable.
    • Note that dependent resource availability should cause a re-queue, NOT a reject.
  • Use durable queues and publisher confirms.
  • Consumers and Producers are both responsible for queue creation.
  • Producers are additionally responsible for routing key bindings.