As part of creating the IoT infrastructure for an organization or business, a lot of efforts go into selecting the sensors, the cloud services, and the analytic solutions. However, there is another decision that is made early during the development process: the selection of the protocol which will facilitate communication between all components.
There are many options among available protocols. Nevertheless, MQTT (Message Queuing Telemetry Transport) remains one of the most commonly used protocols in the context of Industrial IoT.
What Is MQTT Protocol?
MQTT is a lightweight communication protocol using publish-subscribe architecture. It is different from direct point-to-point connection since the protocol uses brokers in order to connect different devices and exchange data.
The architecture includes three major elements:
Publishers – devices or applications which are sending data;
Broker – the server which accepts and distributes data;
Subscribers – devices or applications which are receiving the data.
Why Developers Like MQTT
Industrial settings are characterized by limited devices, unstable networks, and numerous connected sensors. MQTT is a protocol that was created specifically to address those concerns.
Some of its pros include:
- Reduced bandwidth consumption
- Reduced processing requirements
- Unreliable network connections support
- Effective communication between numerous devices
- Compatibility with the cloud and edge platforms
As a result, MQTT is especially efficient for remote monitoring and distributed industrial solutions because of reduced network utilization.
Typical Use Cases for Industrial IoT
The list of use cases where MQTT can be applied includes:
- Equipment monitoring
- Networks of environmental sensors
- Predictive maintenance solutions
- Energy management systems
- Warehouse automation
- Asset monitoring from a distance
- Line of production telemetry
For all these use cases, devices send data while dashboards, analytics tools, and automation systems receive data through subscription.
Quality of Service (QoS)
There is an important attribute that makes MQTT particularly appealing – Quality of Service (QoS) can be configured in different levels.
It is possible to choose among:
QoS 0: the messages are sent once, no delivery confirmation is required
QoS 1: the messages are sent at least once
QoS 2: the messages are delivered exactly once.
Security considerations
Although MQTT is lightweight, one should never neglect security.
Some good practices include:
- Encryption using TLS
- Authentication of the clients
- Role-Based Access Control
- Restriction of the broker access
- Communication monitoring for anomalies
- Updates of the brokers and clients library
Designing a secure architecture is a good way to prevent attacks against the industrial systems.
MQTT vs. HTTP
Sometimes developers tend to consider HTTP instead of MQTT when designing their IoT infrastructure.
HTTP protocol is good for request-response and web service communication, however, it becomes inefficient when devices have to send frequent updates.
Publish/Subscribe pattern of MQTT makes the protocol more appropriate for streaming telemetry data and consuming less bandwidth and less latency.
It does not replace HTTP protocol but rather supplements it performing real-time communication while HTTP supports configuration interfaces, APIs, administrative functions etc.
Scaling Planning
When IoT deployments increase, the topic of scalability becomes more relevant.
Among the things to think about are:
- Broker clustering
- Topic hierarchy
- Message retention
- Authentication of the devices
- Monitoring brokers
- Fault tolerance and redundancy
Thinking about these components beforehand will make it easier to deploy and manage thousands – or even millions – of connected devices.
Concluding Remarks
Selecting a good communication protocol is essential in developing reliable Industrial IoT systems. MQTT has stayed popular because it addresses actual issues with an elegant solution.
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MQTT can become your key to developing reliable IIoT systems.
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