Message Bus

Message Busses are a set of queues which one or more consumers can pull messages from and act on. They are useful for asynchronous processing of data that is generated at an earlier time. Decoupling the creation of “there is work to do” from the processing of that work is a powerful ability that leads to flexible workflows.

Q2 uses the Kafka message bus, though its idiosyncrasies are not relevant for its use. Developers need only concern themselves with the queueing and/or handling of messages using the same tools and interface available throughout the rest of the Caliper SDK.

For sending or serializing messages themselves, the Message Bus module is a great place to start.

If you are looking to build a Handler that consumes messages from an already existing bus queue (or topic, in the Kafka parlance), take a look at the Message Bus Request Handler.