This application example contains the source files to build a Databus Ping Pong application implemented in Node.js.
This application example shows how to connect to the Databus via MQTT and how to publish and subscribe data using an implementation in Node.js. The Flow Creator is used to exchange data between different topics within the Databus.
This implementation example uses the node:14.17.1-alpine image as the base layer and runs the provided script after installing all necessary dependencies.
This example also shows two ways of configuring the application:
- configuration via file upload (fixed configuration file)
- configuration via system app Configuration Service (custom configuration UI with JSON Forms)
The application includes a MQTT client to subscribe to one topic of the Databus and waits to receive data. When data arrives, it publishes a corresponding answer to a second topic of the Databus. If it receives the string "Ping", it will answer with "Pong" and the other way around.
The names of the Databus topics as well as the credentials used by the application can be configured via different options, otherwise environmental variables included in the docker-compose file are used.
- Industrial Edge Management (IEM) V1.5.2-4 / V1.11.8
- Databus Configurator V2.0.0-5
- Databus V2.0.0-4
- Flow Creator V 1.12.0-1
- IE App Configuration Service V1.2.2
- Industrial Edge Device (IED) V1.10.0-9
- Industrial Edge App Publisher V1.10.5
- Docker Engine V20.10.3
- Docker Compose V2.4
- IED is onboarded to a IEM
- Databus Configurator is deployed to the IEM
- IE Configuration Service is deployed to the IEM
- Databus is deployed to the IED
- Flow Creator is deployed to the IED
Please refer to the Installation section of the Ping Pong in C# repository on how to build and deploy the application to an IED. Just use the source files from this repository and follow the instructions.
- Build application
- Configuring the Industrial Edge Databus
- Create configuration for the application
- Upload the application to the Industrial Edge Management
- Configuring and deploying the application to a Industrial Edge Device
Once the application is successfully deployed to the IED, it can be tested using the Flow Creator.
On the IED restart the PingPong application, to ensure the right configuration is used. Then open the app Flow Creator and set it up as following:
- Connect an "inject" node with a "mqtt out" node
- Connect a "mqtt in" node with a "debug" node
- Configure the mqtt-nodes to connect to the databus (mqtt broker, username, password)
- Set the topics of the mqtt-nodes according to the configuration of the application (here: "topic1" to publish to, "topic2" to subscribe to)
Deploy the flow and test by injecting a string payload into the mqtt in node. If the string is "Ping", the application will answer with "Pong". If the string is "Pong" the application will answer with "Ping".
The finished flow is available here and can be imported into the Flow Creator.
- You can find further documentation and help in the following links
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