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Guide to Coreflux MQTT Broker


MQTT (Message Queuing Telemetry Transport) is a lightweight messaging protocol ideal for IoT applications due to its low bandwidth usage and efficient data transmission. Coreflux MQTT Broker serves as a pivotal component in IoT ecosystems, enabling seamless device-to-device and device-to-server communication.

Key Features of Coreflux MQTT Broker

  • Lightweight Protocol: Ideal for constrained environments like IoT devices.
  • Efficient Data Transmission: Minimizes network bandwidth usage.
  • Reliable Message Delivery: Offers various levels of Quality of Service (QoS).
  • Secure Communication: Supports TLS/SSL for encrypted data transfer.


Message Queuing Telemetry Transport (MQTT) is a lightweight, publish-subscribe network protocol that transports messages between devices. The protocol, designed for low-bandwidth, high-latency or unreliable networks, is ideal for Internet of Things (IoT) applications where a small code footprint is required and/or network bandwidth is at a premium.

The Publish-Subscribe Model

Unlike traditional client-server models, where a client communicates directly with an endpoint, MQTT uses a publish-subscribe model to decouple the producer of a message (publisher) from the consumer of a message (subscriber). This model is inherently scalable and allows for efficient information distribution.

graph LR
    broker[MQTT Broker]

    client1[Client 1 - Publisher] -->|Publishes to 'topic/a'| broker
    client2[Client 2 - Subscriber] -->|Subscribes to 'topic/a'| broker
    client3[Client 3 - Sub/Pub] -->|Publishes to 'topic/b'| broker
    client3 -->|Subscribes to 'topic/a & b'| broker
    client4[Client 4 - Publisher] -->|Publishes to 'topic/a'| broker

    broker -->|Sends 'topic/a' messages| client2
    broker -->|Sends 'topic/a' messages| client3
    broker -->|Sends 'topic/b' messages| client3
The diagram illustrates the interactions between an MQTT broker and four clients in a typical MQTT publish/subscribe scenario. Here's an explanation of what happens in this setup:

  • The MQTT Broker

    Is the central node in this communication model. It is responsible for managing the transmission of messages between the clients. The broker receives all messages from the publishers and then routes these messages to the appropriate subscribers based on the topic of the message.

  • Client 1 - Publisher

    Client 1 is configured as a publisher. It sends messages to the MQTT Broker on 'topic/a'. This means that any data or information Client 1 publishes will be under this topic.

  • Client 2 - Subscriber

    Client 2 is a subscriber to 'topic/a'. It is interested in receiving messages that are published on this topic. When Client 1 publishes a message on 'topic/a', the MQTT Broker forwards this message to Client 2.

  • Client 3 - Subscriber/Publisher

    Client 3 has a dual role; it acts both as a subscriber and a publisher. As a publisher, it sends messages to the MQTT Broker on 'topic/b'. As a subscriber, it is interested in messages from both 'topic/a' and 'topic/b'. Therefore, it receives messages from both these topics, sent by the broker. This includes messages from Client 1 and its own messages on 'topic/a', as well as its messages on 'topic/b'.

  • Client 4 - Publisher

    Similar to Client 1, Client 4 is also a publisher to 'topic/a'. It sends its messages to the MQTT Broker, which then forwards these messages to all subscribers of 'topic/a', which in this case includes Client 2 and Client 3.

  • Message Routing

    The MQTT Broker plays a crucial role in routing messages. It does not send messages to clients that have not subscribed to the relevant topic. In this scenario, messages published on 'topic/a' by Client 1 and Client 4 are received by both Client 2 and Client 3. Messages published on 'topic/b' by Client 3 are only received by Client 3 itself, as it's the only subscriber to 'topic/b'.

Topics and Brokers

  • Topics: In MQTT, messages are published on topics. A topic is a simple string that the broker uses to filter messages for each connected client.
  • Broker: The broker is the heart of the MQTT protocol. It is responsible for dispatching all messages between the sender and the appropriate receiver. Each client that publishes a message sends it to the broker, which then forwards the message to all clients subscribed to that topic.
  • Client: Any device that sends (publishes) or receives (subscribes) messages.

Quality of Service (QoS)

MQTT offers three levels of Quality of Service (QoS) for message delivery: - QoS 0 (At most once): The message is delivered at most once, or it may not be delivered at all. It's the fastest and least reliable mode. - QoS 1 (At least once): This ensures that a message is delivered at least once to the receiver. However, the message may be delivered more than once. - QoS 2 (Exactly once): This is the safest and slowest service level, where the message is guaranteed to be delivered exactly once.

MQTT in IoT Applications

MQTT (Message Queuing Telemetry Transport) has become a cornerstone in the Internet of Things (IoT) due to its simplicity, efficiency, and reliability. This lightweight messaging protocol is designed to facilitate communication in environments where resources are limited and network reliability can be inconsistent. Here are some key areas where MQTT is particularly effective in IoT:

  1. Home Automation: In smart homes, MQTT is used to control and monitor devices like lighting, heating, and security systems. Its low bandwidth requirements and real-time capabilities allow for immediate responses to user commands or sensor inputs, enhancing the user experience in home automation systems.

  2. Industrial IoT (IIoT): MQTT is widely used in industrial settings for machine-to-machine communication. It enables real-time monitoring of industrial equipment, facilitating predictive maintenance and efficient operations. MQTT's reliability is crucial in these environments, where data must be accurately and promptly communicated to prevent downtime or accidents.

  3. Agriculture: In precision agriculture, MQTT is used to connect various sensors deployed across farms to monitor conditions like soil moisture, temperature, and crop health. This data is vital for making informed decisions about irrigation, harvesting, and resource allocation.

  4. Healthcare: MQTT is employed in remote patient monitoring systems, where it transmits vital health data from wearable devices to healthcare providers. Its efficient use of bandwidth and ability to operate over unstable networks ensures continuous monitoring, which is critical for patient care.

  5. Transportation and Logistics: MQTT facilitates real-time tracking of vehicles and shipments. It helps in optimizing routes, monitoring vehicle health, and ensuring timely delivery of goods, which is essential in logistics and supply chain management.

Efficiency in IoT

  1. Low Bandwidth Usage: MQTT messages are small and lightweight, making the protocol ideal for environments where network bandwidth is limited. This is particularly important in IoT applications where devices often rely on cellular or other low-bandwidth networks.

  2. Optimized for Unreliable Networks: MQTT can maintain stable communication even over unreliable networks. This is crucial for IoT devices deployed in remote or challenging environments, where network connectivity may be intermittent.

  3. Minimal Power Consumption: The protocol's efficiency translates into lower power consumption, which is vital for battery-operated IoT devices. MQTT's ability to send concise messages without requiring constant connection helps in prolonging battery life.

  4. Flexible Quality of Service Levels: MQTT offers different levels of Quality of Service (QoS) to balance between message delivery assurance and network resource usage. This flexibility allows IoT applications to choose the appropriate QoS level based on their specific requirements.

  5. Retained Messages and Last Will: MQTT's features like retained messages and last will ensure that important information is not lost, even if the connection is temporarily disrupted. This is particularly useful in monitoring applications where data continuity is essential.

By leveraging MQTT, IoT applications can achieve a balance between real-time communication, resource efficiency, and reliability, making it an ideal protocol for the diverse needs of the IoT world.