Reading data
Before you can read data from a stream, you need to subscribe to an event of the Streaming Reader service such as ParameterData or EventData.
Read the Subscriptions and Events reference guide.
Example
The following code sample shows how to use the SignalR client library to:
-
Establish a connection to Quix.
-
Subscribe to a parameter data stream (you can subscribe to multiple streams using the special wildcard character
*). -
Receive data from that stream.
-
Unsubscribe from the event.
In the following Node.js code, click + to see the annotation:
// Use with Demo Data (for example)
var signalR = require("@microsoft/signalr");
const options = {
accessTokenFactory: () => 'YOUR_ACCESS_TOKEN'
};
const connection = new signalR.HubConnectionBuilder()
.withUrl("https://reader-YOUR_ENVIRONMENT_ID.platform.quix.io/hub", options)
.build();
// Establish connection (1)
connection.start().then(() => {
console.log("Connected to Quix.");
// Subscribe to parameter data stream (2)
connection.invoke("SubscribeToParameter", "your-topic-name", "your-stream-id", "your-parameter-id");
// Read data from the stream (3)
connection.on("ParameterDataReceived", data => {
console.log("topicId: " + data.topicId);
console.log("streamId: " + data.streamId);
console.log("EngineRPM values: " + data.numericValues.EngineRPM);
// Unsubscribe from stream (4)
connection.invoke("UnsubscribeFromParameter", "your-topic-name", "your-stream-id", "your-parameter-id");
});
});
- Establish the connection to Quix.
- Subscribe to a parameter data stream (you can subscribe to multiple streams using the special wildcard character
*). - Read data from the stream.
- Unsubscribe from the stream.
Note that SignalR will confirm its connection method, with logging such as the following: