How to Transfer Data from MQTT to Kafka

Open Automation Software can be used to transfer data from a MQTT broker to a Kafka cluster, locally or over a network. This guide walks you through downloading and installing OAS, configuring a MQTT data source, a tag, and a Kafka publisher, and finally publishing the tag using the Kafka publisher.

For this guide on how to transfer data from an MQTT source to a Kafka cluster you will need:

• To install MQTT Explorer or a similar tool for publishing messages to a MQTT broker and subscribing to messages in a MQTT broker
• Docker installed in Linux or Windows including the docker-compose utility

1 - Download and Install OAS

If you have not already done so, you will need to download and install the OAS platform.

Fully functional trial versions of the software are available for Windows, Windows IoT Core, Linux, Raspberry Pi and Docker on our downloads page.

On Windows, run the downloaded setup.exe file to install the Open Automation Software platform. For a default installation, Agree to the End User License Agreement and then click the Next button on each of the installation steps until it has completed.

If you'd like to customize your installation or learn more, use the following instructions:

• Windows Installation
• Linux Installation
• Raspberry Pi Installation
• Docker Installation

The OAS Service Control application will appear when the installation finishes on Windows.

Click on each START SERVICE button to start each of the three OAS services.

2 - Configure OAS

Web Configuration Application

Configuration of the OAS server is performed from the built-in Web Configuration Application. This is the main application for accessing any settings within the OAS server and is completely self-contained within the server.

You can reach this by opening your browser to:

http://<your server>:58725/app/config

If you are browsing from the OAS machine itself, you can use localhost, otherwise use the IP address of the machine. You will also need to ensure port 58725 is open on both the client and the server or you may not be able to reach the application.

On a new installation the OAS engine has no accounts yet, so the first screen you see is Create Admin Account. Once the administrator account exists that screen is not shown again, and browsing to the application displays the sign in screen instead.

1. Enter a name for the administrator in the Admin user name field. Typically you would use admin, but you can use whatever name you choose.

2. Enter a password in the Password field, then enter the same password again in the Confirm password field.

3. Click on the Create admin & sign in button. The account is created and you are signed in to the engine.

To sign in from then on, enter the Network node of the OAS engine, then the Username and Password of your account, and click on the Sign in button.

Legacy Configuration Application

1. From your operating system start menu, open the Configure OAS application.

2. Select the Configure > Tags screen.

   Important

   If this is the first time you have installed OAS, the AdminCreate utility will run when you select a screen in the Configure menu. This will ask you to create a username and password for the admin user. This user will have full permissions in the OAS platform.

   For further information see Getting Started - Security.

3. If this is the first time you are logging in, you will see the AdminCreate utility. Follow the prompts to set up your admin account. Otherwise, select the Log In menu button and provide the Network Node, username and password.

   

   

3 - Create a Kafka test cluster using Docker

In this step you will create a local Kafka cluster. To simplify the deployment you will need to have Docker installed including the docker-compose utility. This method allows you to create a cluster very quickly for testing purposes and remove it again when you are done.

1. Create a new folder such as Kafka and inside the folder create a new docker-compose.yml file with the following definition.

   services:
       zookeeper:
           image: confluentinc/cp-zookeeper:latest
           container_name: zookeeper
           ports:
               - "2181:2181"
           environment:
           ZOOKEEPER_CLIENT_PORT: 2181
           ZOOKEEPER_TICK_TIME: 2000
   
       kafka:
           image: confluentinc/cp-kafka:latest
           container_name: kafka
           ports:
               - "9092:9092"
           environment:
           KAFKA_BROKER_ID: 1
           KAFKA_ZOOKEEPER_CONNECT: zookeeper:2181
           KAFKA_ADVERTISED_LISTENERS: PLAINTEXT://localhost:9092
           KAFKA_LISTENER_SECURITY_PROTOCOL_MAP: PLAINTEXT:PLAINTEXT
           KAFKA_OFFSETS_TOPIC_REPLICATION_FACTOR: 1
   
   

2. Open a command line or bash terminal in the Kafka folder and use the following command to start a new container. This will download the image and all its dependencies and may take a few minutes.

   docker-compose up -d

3. Create a new topic called temperature using the following command.

   docker exec kafka kafka-topics --create --topic temperature --bootstrap-server localhost:9092 --partitions 1 --replication-factor 1

4 - Configure MQTT Data Source

In the following steps you will create and configure a MQTT Connector to connect to a third party broker so that tags will be able to subscribe to a topic. For the purposes of this guide, you will connect to the public HiveMQ broker.

1. Select Drivers in the sidebar.

2. Click + Add, enter a meaningful Driver Interface Name to give this driver interface instance a unique name, and click Create. Once created, the driver interface name should appear in the list of drivers.

3. Ensure the following parameters are configured:

   • Driver: MQTT
   • IP Address: broker.hivemq.com
   • Port: 1883
   • Client ID: OAS_Client_123

   

   The app flags the empty User Name and Password fields. The public HiveMQ broker accepts anonymous connections, so leave them blank here. Fill them in if the broker you are connecting to requires authentication.

   Tips

   If you are having trouble reading a value in later steps, try to change the Client ID to something else as each client ID connecting to the broker must be unique.

4. Turn on Enable and click on the Apply changes button. The driver interface is not active until it is enabled and the changes are applied.

   

5 - Add Tags

In this step you will add two tags. One tag to represent a JSON payload coming from an external data source and a second Tag to represent the sensor value.

1. Select Tags in the sidebar.

2. If you want to add a Tag at the root of the tag list, make sure no Tag Group is selected and click on the + button, then choose Add tag.

   

   If you want to add a Tag to a Tag Group, select the Tag Group first and then click on the + button and choose Add tag here.

   You can also add Tag Groups by choosing Add group.

3. Enter TemperatureSensorJSON as the Tag name and click the Create button.

   

4. Repeat the above two steps and add another Tag with the name TemperatureSensor.

   

6 - Assign MQTT as Tag Data Source

You will now set the Tag's data source to the MQTT driver interface that you created previously.

At the end of this section you will need to use a tool like MQTT Explorer to publish a value to your Tag.

1. Select the Tag that will source data from the MQTT data source.

   

2. Set the following properties:

   • Data Type: JSON
   • Data Source: MQTT
   • Select Driver Interface: MQTT Data Source
   • Topic: oas/temperature

   

3. Click on the Apply changes button to apply the changes.

4. Using an MQTT testing tool to publish messages, such as MQTT Explorer, publish a JSON message to the oas/temperature topic.

   {
       "temperature": 24.9
   }
   

   

   

   

5. Check that the quality status is Good and you can see the JSON value.

   

7 - Parse JSON Payload

In this step you will extract the sensor value from the JSON payload using a Calculation Tag and JSON functions.

1. Select the Tag that will represent the temperature value.

   

2. Set the Data Source value to Calculation.

3. Next to the Calculation field click on the Edit… button.

4. In the Edit Calculation window enter the following function.

   JSONQUERY([TemperatureSensorJSON.Value], "$.temperature")
   

   This will extract the temperature field from the TemperatureSensorJSON Tag value.

   Click the OK button to save the calculation.

   

5. Click on the Apply changes button to apply the changes.

6. You should now see the sensor value displayed for the Tag.

8 - Configure Kafka Producer

In the following steps you will create and configure a Kafka Connector connecting to a local Kafka cluster on port 9092. This connector will act as a Producer where Tags are published to a topic in the cluster.

1. Select Drivers in the sidebar.

2. Click + Add, enter a meaningful Driver Interface Name to give this driver interface instance a unique name (for example Kafka Producer), and click Create. Once created, the driver interface name should appear in the list of drivers.

3. Ensure the following parameters are configured:

   • Driver: Kafka
   • Bootstrap Servers: localhost:9092
   • Security Protocol: Plaintext
   • Client Id: oas-kafka-producer

   

   The app flags the Bootstrap Servers field because it is still the default localhost:9092. That is the address of the local test cluster you created, so leave it as it is. Change it if your broker is on another host or port.

4. Turn on Enable and click on the Apply changes button. The driver interface is not active until it is enabled and the changes are applied.

   

9 - Publish Selected Tags in Kafka Producer

In this step you will select the Tags that you want to publish to the Kafka cluster.

1. In the Drivers screen, select the Kafka driver instance that you created in the previous section (for example Kafka Producer).

2. Make sure the Publish Selected Tags toggle is turned on.

   

3. In the Tags To Publish table click on the Add button.

   

4. The Publish tag window will appear. Click on the … button to browse for a Tag, select the Tag you want to add in the left hand panel and then ensure the Value property is selected, and click on the Use this tag button.

   

5. Back in the Publish tag window the Id defaults to the full Tag path (e.g. TemperatureSensor.Value). If you want to set your own property name, you can change the Id field to your own custom value. Click on the OK button.

   

6. The Tag has now been added to the list. You can add other Tags by repeating steps 3 to 5.

   

7. Click on the Apply changes button.

10 - Verify Messages are Published to Kafka Cluster

In this step you will confirm that OAS is successfully publishing your selected Tags to the Kafka cluster.

1. Run the following command in a terminal or command line window to start listening for new messages on the oas_tags topic which is the default topic for the Publish Selected Tags configuration.

   docker exec kafka kafka-console-consumer --topic oas_tags --bootstrap-server localhost:9092
   

   Info

   You may receive a warning message, because the oas_tags topic doesn't exist yet. You can safely ignore this as it will be created automatically.

2. Any changes your TemperatureSensor tag value should be published within 10 seconds to the terminal window.

   {
       "values": [
           {
               "id": "TemperatureSensor",
               "value": 24.902344,
               "quality": true,
               "timestamp": "2025-05-20T09:23:41.332Z"
           }
       ]
   }
   

3. To stop listening for new messages press the Ctrl-C shortcut combination on your keyboard.

11 - Save Changes

Once you have successfully configured your OAS instances, make sure you save your configuration.

On each configuration page that has a Save button, click on it.

If this is the first time you are saving the configuration, or if you are changing the name of the configuration file, OAS will ask you if you want to change the default configuration file.

If you select Yes then OAS will make this configuration file the default and if the OAS service is restarted then this file will be loaded on start-up.

If you select No then OAS will still save your configuration file, but it will not be the default file that is loaded on start-up.