Chapter 12. Connect to MQTT

MQ Telemetry Transport (MQTT) is a lightweight, machine-to-machine, internet of things, connectivity protocol. In an integration, you can obtain messages from or publish messages to an MQTT broker. To do this, create a connection to the MQTT broker of interest and then add that connection to an integration. Details are in the following topics:

12.1. Create a connection to an MQTT broker

In an integration, to obtain messages from or publish messages to an MQTT broker, create a connection to the MQTT broker of interest and then add that connection to an integration.

Prerequisite

You must know the URL for the MQTT broker that you want to connect to.

Procedure

  1. In Fuse Online, in the left panel, click Connections to display any available connections.
  2. In the upper right, click Create Connection to display connectors.
  3. Click the MQTT Message Broker connector.
  4. To configure the connection:

    1. In the MQTT broker URL field, enter the location of the MQTT broker that you want to send data to or obtain data from. This is the only required field.
    2. In the User Name field, optionally enter the user name for the MQTT account whose credentials you want to use to access the broker.
    3. In the Password field, if you specified a user name, then specify the password associated with that account.
    4. In the Client ID field, optionally enter the ID that allows connections to close and reopen without missing messages. The connection must subscribe to or publish to a topic.
  5. Click Validate. Fuse Online immediately tries to validate the connection and displays a message that indicates whether validation is successful. If validation fails, revise the input parameters and try again.
  6. If validation is successful, click Next.
  7. In the Connection Name field, enter your choice of a name that helps you distinguish this connection from any other connections. For example, you might enter MQTT West.
  8. In the Description field, optionally enter any information that is helpful to know about this connection.
  9. In the upper right, click Create to see that the connection you created is now available. If you entered the example name, you would see that MQTT West appears as a connection that you can choose to add to an integration.

12.2. Obtain a message from an MQTT broker

To trigger execution of an integration based on receiving a message from an MQTT broker, add an MQTT connection as the start connection. When the integration is running, the MQTT connection continuously watches for messages on the MQTT queue or topic that you specify. When the connection finds a message, it passes it to the next step in the integration. An MQTT connection handles one message at a time.

Prerequisite

You created an MQTT connection.

Procedure

  1. In the Fuse Online panel on the left, click Integrations.
  2. Click Create Integration.
  3. On the Choose a Start Connection page, click the MQTT connection that you want to use to start the integration.
  4. On the Choose an Action page, click the Subscribe action to receive messages from the queue or topic that you specify.
  5. In the MQTT queue/topic name field, enter the name of the queue or topic to subscribe to in order to receive data.
  6. Click Next to specify the action’s output type.
  7. In the Select Type field, if the data type does not need to be known, accept Type specification not required and then, at the bottom, click Done. You do not need to follow the rest of these instructions.

    Otherwise, select one of the following as the schema type:

    • JSON schema is a document that describes the structure of JSON data. The document’s media type is application/schema+json.
    • JSON instance is a document that contains JSON data. The document’s media type is application/json.
    • XML schema is a document that describes the structure of XML data. The document’s file extension is .xsd.
    • XML instance is a document that contains XML data. The document’s file extension is .xml.
  8. In the Definition input box, paste a definition that conforms to the schema type you selected. For example, if you select JSON schema then you would paste the content of a JSON schema file, which has a media type of application/schema+json.
  9. In the Data Type Name field, enter a name that you choose for the data type. For example, suppose you are specifying a JSON schema for vendors. You can specify Vendor as the data type name.

    You will see this data type name when you are creating or editing an integration that uses the connection for which you are specifying this type. Fuse Online displays the type name in the integration visualization panel and in the data mapper.

  10. In the Data Type Description field, provide information that helps you distinguish this type. This description appears in the data mapper when you hover over the step that processes this type.
  11. Click Done.

Result

The connection appears in the integration flow in the location where you added it.

12.3. Publish a message to an MQTT broker

In an integration, you can publish a message to an MQTT broker to finish an integration. To do this, add an MQTT connection as the integration’s finish connection. To publish a message to an MQTT broker in the middle of integration, add an MQTT connection to an integration after the start connection and before the finish connection.

Prerequisites

  • You created an MQTT connection.
  • You are creating or editing an integration and the integration already has a start connection.

Procedure

  1. On the Choose a Finish Connection page, do one of the following:

    • To finish an integration by publishing a message, click the MQTT connection that you want to use.
    • To publish a message in the middle of an integration, click the connection that you want to use to finish the integration. Configure that connection. When the finish connection is part of the integration, in the left panel, hover over the plus sign where you want to add an MQTT connection and click Add a connection. Click the MQTT connection that you want to use to publish a message in the middle of an integration.
  2. On the Choose an Action page, click Publish.
  3. In the MQTT queue/topic name field, specify the name of the queue or topic to publish the message to.
  4. Click Next to specify the action’s input type.
  5. In the Select Type field, if the data type does not need to be known, accept Type specification not required and then, at the bottom, click Done. You do not need to follow the rest of these instructions.

    Otherwise, select one of the following as the schema type:

    • JSON schema is a document that describes the structure of JSON data. The document’s media type is application/schema+json.
    • JSON instance is a document that contains JSON data. The document’s media type is application/json.
    • XML schema is a document that describes the structure of XML data. The document’s file extension is .xsd.
    • XML instance is a document that contains XML data. The document’s file extension is .xml.
  6. In the Definition input box, paste a definition that conforms to the schema type you selected. For example, if you select JSON schema then you would paste the content of a JSON schema file, which has a media type of application/schema+json.
  7. In the Data Type Name field, enter a name that you choose for the data type. For example, suppose you are specifying a JSON schema for vendors. You can specify Vendor as the data type name.

    You will see this data type name when you are creating or editing an integration that uses the connection for which you are specifying this type. Fuse Online displays the type name in the integration visualization panel and in the data mapper.

  8. In the Data Type Description field, provide information that helps you distinguish this type. This description appears in the data mapper when you hover over the step that processes this type.
  9. Click Done.

Result

The connection appears in the integration flow in the location where you added it.