MQTT

MQTT which stands for Message Queuing Telemetry Transport, is a lightweight and efficient messaging protocol designed for low-bandwidth, high-latency, or unreliable networks. It is widely used in the Internet of Things (IoT) and other applications where devices and systems need to communicate in a publish-subscribe system. MQTT is known for its simplicity and minimal overhead, making it suitable for constrained devices and scenarios where network resources are limited.

In MQTT, there are two main components: publishers and subscribers. Publishers send messages (called "publish" messages) to specific topics, and subscribers receive messages by subscribing to those topics. This decoupled communication model is very flexible and scalable.

Key features of MQTT include:

• Quality of Service (QoS) levels: MQTT supports different levels of message delivery assurance, ranging from "at most once" to "exactly once."

• Last Will and Testament: Clients can specify a "last will" message to be sent by the broker on a specific topic if the client unexpectedly disconnects.

• Retained messages: The broker can retain the last message sent on a topic, ensuring that new subscribers receive the last known state.

• Session persistence: MQTT brokers can maintain client sessions across disconnections, ensuring clients receive messages they missed during downtime.

A free to use MQTT service offered by Ghasworx can be utilized here Ghasworx mqtt.

Here's a high-level overview of how MQTT operates:

• Broker: MQTT communication relies on a central message broker (server). The broker is responsible for receiving all messages from publishers and distributing them to the relevant subscribers. It acts as an intermediary, managing message routing.

• Publishers: These are devices or applications that produce data to be shared. Publishers connect to the MQTT broker and send messages to specific topics. Topics act as message channels or categories, helping subscribers choose which data they're interested in.

• Subscribers: Subscribers are devices or applications interested in specific topics. They connect to the MQTT broker and subscribe to one or more topics. Once subscribed, they will receive all messages published on those topics.

• Topics: Topics are essentially the "channels" through which messages are sent. Publishers send messages to specific topics, and subscribers receive messages from topics to which they are subscribed.

• Quality of Service (QoS): MQTT supports different QoS levels, which define the message delivery guarantee. There are three QoS levels:
• QoS 0 (At most once): The message is sent but not guaranteed to arrive. This is the least type to have an overhead on the network.
• QoS 1 (At least once): The message is guaranteed to arrive but may be duplicated. This type is in between QoS 0 and QoS 2 in terms of traffic consumption.
• QoS 2 (Exactly once): The message is guaranteed to arrive exactly once. This type utilizes the network more than both previous QoS types.

• Retained Messages: MQTT allows for retained messages, which means that the broker can store the last message (only the last message) sent on a topic. This is helpful for subscribers who want to know the most recent value when they subscribe to a topic.

• Last Will and Testament (LWT): MQTT clients can specify a "last will" message that the broker will send if the client unexpectedly disconnects. This is useful for scenarios where clients need to indicate their status to others.

• Keep Alive: MQTT clients exchange "keep alive" messages with the broker to confirm their connection status. If a client fails to send a keep-alive message within a specified time, the broker will assume the client is disconnected.

A free to use MQTT service offered by Ghasworx can be utilized here Ghasworx mqtt.

Overall, MQTT is a robust and reliable protocol for connecting and controlling IoT devices and is widely used in home automation, industrial automation, and many other IoT applications.