The various services in a Microservice based application can communicate with each other via a message broker. A message broker is a physical component that handles the communication between services. Instead of communicating with each other, services communicate only with the message broker. An application sends a message to the message broker, providing the logical name of the receivers. The message broker looks up the services registered under the logical name and then passes the message to them:

Such a service in Azure may be realized by using Azure Service Bus Topics and Subscriptions. Each service may publish messages on the topic and specify a set of properties of the message that identify the receiver this message should reach to. The services may create a number of subscriptions on the topic to receive messages addressed to them.