MQTT Client¶

Characteristics¶

MQTT is an OASIS standard messaging protocol for the Internet of Things (IoT). To learn more about the standard, visit the MQTT website.

Information Model Requirements¶

• The first node after the root node must be of type Events or Variables with a Simple Data Type or Custom Data Type.
• Properties can be used for dynamic topics within Events and Complex Variables.

• The following Node Types can be used under the Event Node:

• Variables with a Simple Data Type represent the key-value pairs.

• Variables with a Custom Data Type represent objects that can contain key-value pairs.
• With Lists, you can aggregate multiple variables.

Complex Variables Nodes¶

Event Nodes¶

Configuration¶

Model¶

1. Select the MQTT Client as Channel Type.
2. Click the Configure button.

1. Select the root model node.

2. Configure the MQTT client:

3. Enter Host and Port of the MQTT Broker used.

4. (Optional) Specify a Client ID.
5. Set the Quality of Service (QoS).
6. If required, configure the credentials.

7. If required, configure TLS:

   • (Optional) Provide CA certificate to validate the host.
   • (Optional) Provide Client certificate and key file for client authentication.
   • (Optional) Provide a prefix for the topic that will be used when publishing messages.
   • If required, adjust the default values for Reconnect interval and the Unit.
   • (Optional) Change the default message options. These can be overwritten for each event.

Events¶

1. Select the event node in the tree on the left.

2. Select the Direction (Producer or Consumer).

3. For Producer, set Retain if required.
4. Configure the topic.
5. Optional: Override the default message options.

Variables¶

1. Select the variable node in the tree on the left.

2. Select the Direction (Producer or Consumer).

3. For Producer, set Retain if required.
4. Configure the topic.
5. Optional: Override the default message options.

Topics¶

The topics for publishing and subscribing can be configured in a static but also dynamic way, where variables and properties are used within the topic.

Producer¶

• In the Model configuration, a prefix (Producer topic prefix) can be configured.
• This prefix will be automatically added to the topics for producer events and variables.
• If variables/properties are going to be used, they need to be written in the ${VariableName} pattern.
• In the producer prefix, only variables that are directly in the root node of the Model can be used.
• In the topic configuration of the events/complex variables, only variable and properties with the complex variable can be used.
• If the topic in the event/complex variable configuration starts with a /, then the prefix will not be added.

Example

Following variable values are used in the example:

Topic Configuration

Consumer¶

• In the Model configuration, a prefix (Consumer topic prefix) can be configured.
• This prefix will be automatically added to the topics for consumer events and variables.
• Variables/properties can be used as wildcards in events and complex variables. They need to be written in the ${VariableName} pattern.
• Wildcards are not supported in the prefix.
• Wildcards variables/properties can only be used for an entire topic segment. For example, MyNamespace/${Factory}/Metrics will be translated into MyNamespace/+/Metrics.
• A partial topic segment is not possible. For example, MyNamespace/Factory:${Factory}/Metrics.
• If the topic in the event/complex variable configuration starts with a /, then the prefix will not be added.

Example