Overview
MQTT is a messaging protocol designed for IoT devices and applications operating on a publish/subscribe model. It's lightweight, efficient, reliable, and allows for real-time communication. MQTT is well-suited for environments with limited resources, where efficient use of power and bandwidth is necessary.
Neuron supports MQTT as one of its communication protocols. The Neuron MQTT plugin allows users to quickly build IoT applications that use MQTT communication between devices and the cloud. Using the MQTT plugin, developers can also publish messages back to IoT devices, triggering device actions such as turning on or off lights, motors, and other equipments. The plugin also supports secure communication with devices, using authentication and encrypted communication protocols to ensure data safety and privacy.
Parameters
These are the available parameters when configuring a node using the MQTT plugin.
| Parameter | Description |
|---|---|
| client-id | MQTT client id for communication, required. |
| upload-topic | Subscription data reporting topic, required |
| format | The json format of reported data, required. There are values format and tags format |
| cache-mem-size | In-memory cache limit (MB) in case of communication failure, required. Range in [0, 1024]. Should not be larger than cache-disk-size. |
| cache-disk-size | In-disk cache limit (MB) in case of communication failure, required. Range in [0, 10240]. If nonzero, cache-mem-size should also be nonzero. |
| host | MQTT Broker host, required. |
| port | MQTT Broker port number, required. |
| username | Username to use when connecting to the broker, optional. |
| password | The password to use when connecting to the broker, optional. |
| ssl | Whether to enable MQTT SSL, default false. |
| ca | CA certificate, required when SSL enabled. |
| cert | client certificate, required when using SSL two way authentication. |
| key | client key, required when using SSL two way authentication. |
| keypass | client key password, optional when using SSL two way authentication. |
Data upload
After subscribing to some south nodes, the Neuron MQTT plugin will publish collected data in JSON to the topic designated by the upload-topic parameter. The exact format of the data reported is controlled by the format parameter. There are two formats, tags-format and values-format.
For more detail information, see MQTT API
Offline data caching
Offline data caching is a feature that allows data to be stored locally on the device running Neuron during network outage. When a network connection becomes available, the MQTT plugin can synchronize data with the broker. This feature is useful in scenarios where network connectivity may be limited, unstable, or intermittent. And provides a critical functionality that can enhance the robustness and reliability of applications built on Neuron.
Offline data caching is controlled by the cache-mem-size and cache-disk-size parameters. The cache-mem-size parameter specified the memory cache size in megabytes, and the max allowed memory cache size is 1GB. The cache-disk-size parameter specified the disk cache size in megabytes, and the max allowed disk cache size is 10GB. When network disruption occurs, the MQTT plugin will store data in the memory cache first, and only flush data to the disk cache when memory cache is full. When network connection restores, the MQTT plugin will publish the cached data to the broker in FIFO (Fist In First Out) order.
You may disable offline data caching by setting both cache-mem-size and cache-disk-size to zero.
Data security
SSL/TLS (Secure Sockets Layer/Transport Layer Security) is a security protocol used to encrypt communication channels between networked devices. It enables secure communication over an insecure network, such as the internet. MQTT over SSL/TLS is a secure method for transmitting MQTT messages between client and the MQTT broker by encrypting the data being transmitted with SSL/TLS encryption. This ensures that all data passed between the clients and the broker are encrypted and secure.
The Neuron MQTT plugin supports running MQTT over SSL. To enable SSL encryption, turn on the ssl parameter when configuring the node, and provide the ca parameter with the CA's certificate. The certificate of the broker you are connecting to should be issued by the provided CA. And if you are using two-way authentication, you should also provide the client certificate, key file, and key file password through the cert, key, and keypass parameters respectively.
Examples
See Connect to MQTT for a quick start example.