Before we dive deep into MQTT, we must understand the publish-subscribe pattern, also known as the pub-sub pattern. In the publish-subscribe pattern, a client that publishes a message is decoupled from the other client or clients that receive the message. The clients don't know about the existence of the other clients. A client can publish messages of a specific type and only the clients that are interested in that specific type of message will receive the published messages.
The publish-subscribe pattern requires a server, also known as a broker. All the clients establish a connection with the server. A client that sends a message through the server is known as the publisher. The server filters ...
