Subscribing Events

Subscribing to events allows your application to receive live updates about changes in data. These events may include measurement updates, file transfers, or other general updates.

It is important to note there are three distinct event types available for subscription:

• Measurement Event
• File Event
• Events (e.g. Edge Rules)

Measurement Events:

To handle incoming measurement data, use the subscribeMeasurements method:

/**
 * Subscribes to measurement events and processes the incoming data.
 *
 * @param {MeasurementMessage} message - Contains the data source configuration and the list of data points.
 */

VL.subscribeMeasurements = (message) => {
  // Implement logic to process the message
  console.log(
    `Data Source Name: ${message.dataSource.name}, 
     Data Point Name: ${message.data.name}`
  );
};

Property	Field	Type	Description
MeasurementMessage	dataSource	IDataSourceConfig	Configuration of the data source.
	data	IDataPointConfig[]	Array of data point configurations.
IDataSourceConfig	id	string	Unique identifier of the data source.
	dataPointsConfigs	ReadonlyArray\<IDataPointConfig>	Array of data point configurations.
	name	string	Name of the data source.
	protocol	DataSourceProtocols	Protocol used by the data source.
	connection_string	string	Connection string for the data source.
	rack	number	Rack number for the data source.
	slot	number	Slot number for the data source.
	asset_id	string (optional)	Asset identifier (optional).
	field_device_type	string (optional)	Type of the field device (optional).
IDataPointConfig	id	string	Unique identifier of the data point.
	name	string	Name of the data point.
	unit	string	Unit of measurement for the data point.
	address	string	Address of the data point.
	read_frequency	string	Frequency at which data is read.
	variable_type	string (optional)	Type of the variable (optional).
	function_type	string (optional)	Function type of the data point (optional).
	edge_only	boolean (optional)	Flag to indicate if it's edge-only (optional).
	disabled	boolean	Flag to indicate if the data point is disabled.

File Events:

To handle incoming file data, use the subscribeFile method:

/**
 * This function subscribes to file events.
 *
 * @param {string} dataString - The file data as a string.

 */
VL.subscribeFile = (dataString) => {
  // Do something with the data
};

General Events:

To handle incoming EdgeBusEvents, use the onEvent method:

/**
 * This function subscribes to general events.
 *
 * @param {IEdgeBusEvent} events - The event message that this function will process.

 */
VL.onEvent = (events) => {
  // Do something with the data
};

IDataSourceConfig object:

This object holds configuration details about a data source.

IEdgeBusEvent

IEdgeBusEvent Structure

Property	Field	Type	Description
measurement	id	string	The identifier for the measurement.
	value	string	The value of the measurement.
edgeEvent	id	string	The identifier for the edge event.
	ts	Date	The timestamp of the edge event.