In some direct communications between microservices, timing may be important, but there are other times where the process can simply be asynchronous; there's no need for an immediate response or confirmation of success, all that is required is to simply run a task. For this approach, the message broker is just perfect.
Some software applications appear a good choice for message brokers, such as RabbitMQ, ActiveMQ, ZeroMQ, Kafka, and Redis. Each of these options has its own peculiarities, some are faster, others are more resilient. Again, the business setting is going to determine which technology is used.
