Display Data examples

This project contains three examples showing how to query data from different services and display it on our custom architecture dashboard.

Services Used

  • FIWARE Orion – Context broker

  • EMQX – MQTT broker

  • PostgreSQL database – Used to store and query data

List of used nodes

  • Inject/Timestamp – Triggers the flow

  • Function – Adds custom JavaScript logic

  • HTTP Request – Sends HTTP requests to external services

  • Debug – Outputs messages to the debug console

  • JSON – Converts data to/from JSON format

  • Change – Updates values within the msg object

  • Websocket - Manages WebSocket connection

  • PostgreSQL node – Executes SQL queries provided via the msg.query property

For details, see Node-RED Documentation

FLOW: Get EMQX Data

This flow retrieves metrics from the EMQX Nodes API. An authorization header is required to access the data.

For details, see Making HTTP Requests in Node-RED.

The received data is structured into an object and sent via WebSocket to the front-end hosted by Node-RED.

FLOW: Get Orion Online Status

This flow checks the status of the FIWARE Orion context broker via an API call. A successful call (HTTP 2xx) confirms the service is accessible.

FLOW: Get Postgres Data

This flow performs a query to count tables in a PostgreSQL database.

For details, see Executing PostgreSQL queries in Node-RED.