A message broker is software that enables applications, systems, and services to communicate with each other and exchange information. The message broker does this by translating messages between formal messaging protocols. This allows interdependent services to “talk” with one another directly, even if they were written in different languages or implemented on different platforms.
Message brokers are architectural designs for validating, transforming and routing messages. They serve as mid-level programs to trigger communication between applications. This helps to minimize the mutual awareness that the applications should possess to be capable of exchanging messages, efficiently employing decoupling.