Connectivity Software User's Guide and Reference
EasySparkplugMetricNotificationEventHandler Delegate
ExampleExample 



OpcLabs.EasySparkplug Assembly > OpcLabs.EasySparkplug Namespace : EasySparkplugMetricNotificationEventHandler Delegate
The source of the event.
An OpcLabs.EasySparkplug.OperationModel.EasySparkplugMetricNotificationEventArgs that contains the event data.
Represents the method that will handle an event raised for notifications related to subscribed Sparkplug metric.
Syntax
'Declaration
 
<ComVisibleAttribute(False)>
Public Delegate Sub EasySparkplugMetricNotificationEventHandler( _
   ByVal sender As Object, _
   ByVal e As EasySparkplugMetricNotificationEventArgs _
) 
'Usage
 
Dim instance As New EasySparkplugMetricNotificationEventHandler(AddressOf HandlerMethod)
[ComVisible(false)]
public delegate void EasySparkplugMetricNotificationEventHandler( 
   object sender,
   EasySparkplugMetricNotificationEventArgs e
)
[ComVisible(false)]
public delegate void EasySparkplugMetricNotificationEventHandler( 
   Object^ sender,
   EasySparkplugMetricNotificationEventArgs^ e
)

Parameters

sender
The source of the event.
e
An OpcLabs.EasySparkplug.OperationModel.EasySparkplugMetricNotificationEventArgs that contains the event data.
Remarks

 

Sparkplug is a trademark of Eclipse Foundation, Inc. "MQTT" is a trademark of the OASIS Open standards consortium. Other related terms are trademarks of their respective owners. Any use of these terms on this site is for descriptive purposes only and does not imply any sponsorship, endorsement or affiliation.

Example
// This example shows how to subscribe to all metrics of a given edge node and display the name and value of the metric with
// each notification.
//
// In order to publish or observe messages for this example, start the SparkplugEdgeNodeConsoleDemo program first.
//
// Find all latest examples here: https://opclabs.doc-that.com/files/onlinedocs/OPCLabs-ConnectivityStudio/Latest/examples.html .
// Sparkplug examples in C# on GitHub: https://github.com/OPCLabs/Examples-ConnectivityStudio-CSharp .
// Missing some example? Ask us for it on our Online Forums, https://www.opclabs.com/forum/index ! You do not have to own
// a commercial license in order to use Online Forums, and we reply to every post.

using System;
using OpcLabs.EasySparkplug;
using OpcLabs.EasySparkplug.OperationModel;

namespace SparkplugDocExamples.Consumer._EasySparkplugConsumer
{
    partial class SubscribeEdgeNodeMetric
    {
        public static void Overload1()
        {
            // Note that the default port for the "mqtt" scheme is 1883.
            var hostDescriptor = new SparkplugHostDescriptor("mqtt://localhost");

            // Instantiate the consumer object and hook events.
            var consumer = new EasySparkplugConsumer();
            consumer.MetricNotification += consumer_Overload1_MetricNotification;

            Console.WriteLine("Subscribing...");
            // In this example, we specify the precise Sparkplug group ID and edge node ID, but allow any metric name.
            consumer.SubscribeEdgeNodeMetric(hostDescriptor, 
                "easyGroup", "easySparkplugDemo", "#");

            Console.WriteLine("Processing notifications for 20 seconds...");
            System.Threading.Thread.Sleep(20 * 1000);

            Console.WriteLine("Unsubscribing...");
            consumer.UnsubscribeAllMetrics();

            Console.WriteLine("Waiting for 5 seconds...");
            System.Threading.Thread.Sleep(5 * 1000);

            Console.WriteLine("Finished.");
        }


        static void consumer_Overload1_MetricNotification(object sender, EasySparkplugMetricNotificationEventArgs eventArgs)
        {
            // Handle different types of notifications.
            Console.WriteLine();
            switch (eventArgs.NotificationType)
            {
                case SparkplugNotificationType.Connect:
                    Console.WriteLine($"Connected to Sparkplug host, client ID: {eventArgs.ClientId}.");
                    break;
                case SparkplugNotificationType.Disconnect:
                    Console.WriteLine("Disconnected from Sparkplug host.");
                    break;
                case SparkplugNotificationType.Data:
                    Console.WriteLine("Received data from Sparkplug host.");
                    Console.WriteLine($"Metric name: {eventArgs.MetricName}");
                    Console.WriteLine($"Value: {eventArgs.MetricData?.Value}");
                    break;
                case SparkplugNotificationType.Birth:
                    Console.WriteLine("Received birth message from Sparkplug host.");
                    Console.WriteLine($"Metric name: {eventArgs.MetricName}");
                    Console.WriteLine($"Value: {eventArgs.MetricData?.Value}");
                    break;
                case SparkplugNotificationType.Death:
                    Console.WriteLine("Received death message from Sparkplug host.");
                    Console.WriteLine($"Metric name: {eventArgs.MetricName}");
                    break;
            }
            if (!eventArgs.Succeeded)
                Console.WriteLine($"*** Failure: {eventArgs.ErrorMessageBrief}");
        }
    }
}
' This example shows how to subscribe to all metrics of a given edge node and display the name and value of the metric with
' each notification.
'
' In order to publish or observe messages for this example, start the SparkplugEdgeNodeConsoleDemo program first.
'
' Find all latest examples here: https://opclabs.doc-that.com/files/onlinedocs/OPCLabs-ConnectivityStudio/Latest/examples.html .
' Sparkplug examples in C# on GitHub: https://github.com/OPCLabs/Examples-ConnectivityStudio-CSharp .
' Missing some example? Ask us for it on our Online Forums, https://www.opclabs.com/forum/index ! You do not have to own
' a commercial license in order to use Online Forums, and we reply to every post.

Imports OpcLabs.EasySparkplug
Imports OpcLabs.EasySparkplug.OperationModel

Namespace Global.SparkplugDocExamples.Consumer._EasySparkplugConsumer
    Partial Class SubscribeEdgeNodeMetric
        Public Shared Sub Overload1()
            ' Note that the default port for the "mqtt" scheme is 1883.
            Dim hostDescriptor = New SparkplugHostDescriptor("mqtt://localhost")

            ' Instantiate the consumer object and hook events.
            Dim consumer = New EasySparkplugConsumer()
            AddHandler consumer.MetricNotification, AddressOf consumer_Overload1_MetricNotification

            Console.WriteLine("Subscribing...")
            ' In this example, we specify the precise Sparkplug group ID and edge node ID, but allow any metric name.
            consumer.SubscribeEdgeNodeMetric(hostDescriptor,
                "easyGroup", "easySparkplugDemo", "#")

            Console.WriteLine("Processing notifications for 20 seconds...")
            Threading.Thread.Sleep(20 * 1000)

            Console.WriteLine("Unsubscribing...")
            consumer.UnsubscribeAllMetrics()

            Console.WriteLine("Waiting for 5 seconds...")
            Threading.Thread.Sleep(5 * 1000)

            Console.WriteLine("Finished.")
        End Sub

        Private Shared Sub consumer_Overload1_MetricNotification(ByVal sender As Object, ByVal eventArgs As EasySparkplugMetricNotificationEventArgs)
            ' Handle different types of notifications.
            Console.WriteLine()
            Select Case eventArgs.NotificationType
                Case SparkplugNotificationType.Connect
                    Console.WriteLine($"Connected to Sparkplug host, client ID: {eventArgs.ClientId}.")
                Case SparkplugNotificationType.Disconnect
                    Console.WriteLine("Disconnected from Sparkplug host.")
                Case SparkplugNotificationType.Data
                    Console.WriteLine("Received data from Sparkplug host.")
                    Console.WriteLine($"Metric name: {eventArgs.MetricName}")
                    Console.WriteLine($"Value: {eventArgs.MetricData?.Value}")
                Case SparkplugNotificationType.Birth
                    Console.WriteLine("Received birth message from Sparkplug host.")
                    Console.WriteLine($"Metric name: {eventArgs.MetricName}")
                    Console.WriteLine($"Value: {eventArgs.MetricData?.Value}")
                Case SparkplugNotificationType.Death
                    Console.WriteLine("Received death message from Sparkplug host.")
                    Console.WriteLine($"Metric name: {eventArgs.MetricName}")
            End Select
            If Not eventArgs.Succeeded Then
                Console.WriteLine($"*** Failure: {eventArgs.ErrorMessageBrief}")
            End If
        End Sub
    End Class
End Namespace
// This example shows how to subscribe to changes of a single metric, and display the value of the metric with each change
// using a callback method that is provided as lambda expression.
//
// In order to publish or observe messages for this example, start the SparkplugEdgeNodeConsoleDemo program first.
//
// Find all latest examples here: https://opclabs.doc-that.com/files/onlinedocs/OPCLabs-ConnectivityStudio/Latest/examples.html .
// Sparkplug examples in C# on GitHub: https://github.com/OPCLabs/Examples-ConnectivityStudio-CSharp .
// Missing some example? Ask us for it on our Online Forums, https://www.opclabs.com/forum/index ! You do not have to own
// a commercial license in order to use Online Forums, and we reply to every post.

using OpcLabs.EasySparkplug;
using System;

namespace SparkplugDocExamples.Consumer._EasySparkplugConsumer
{
    partial class SubscribeEdgeNodeMetric
    {
        public static void CallbackLambda()
        {
            // Note that the default port for the "mqtt" scheme is 1883.
            var hostDescriptor = new SparkplugHostDescriptor("mqtt://localhost");

            // Instantiate the consumer object.
            var consumer = new EasySparkplugConsumer();

            Console.WriteLine("Subscribing...");
            // The callback is a lambda expression the displays the value
            // In this example, we specify the precise Sparkplug group ID, edge node ID, and metric name.
            consumer.SubscribeEdgeNodeMetric(hostDescriptor, 
                "easyGroup", "easySparkplugDemo", "Random",
                (sender, eventArgs) =>
                {
                    if (eventArgs.Succeeded)
                    {
                        if (eventArgs.HasData)
                            Console.WriteLine("Value: {0}", eventArgs.MetricData?.Value);
                    }
                    else
                        Console.WriteLine("*** Failure: {0}", eventArgs.ErrorMessageBrief);
                });

            Console.WriteLine("Processing notifications for 20 seconds...");
            System.Threading.Thread.Sleep(20 * 1000);

            Console.WriteLine("Unsubscribing...");
            consumer.UnsubscribeAllMetrics();

            Console.WriteLine("Waiting for 5 seconds...");
            System.Threading.Thread.Sleep(5 * 1000);

            Console.WriteLine("Finished.");
        }
    }
}
' This example shows how to subscribe to changes of a single metric, and display the value of the metric with each change
' using a callback method that is provided as lambda expression.
'
' In order to publish or observe messages for this example, start the SparkplugEdgeNodeConsoleDemo program first.
'
' Find all latest examples here: https://opclabs.doc-that.com/files/onlinedocs/OPCLabs-ConnectivityStudio/Latest/examples.html .
' Sparkplug examples in C# on GitHub: https://github.com/OPCLabs/Examples-ConnectivityStudio-CSharp .
' Missing some example? Ask us for it on our Online Forums, https://www.opclabs.com/forum/index ! You do not have to own
' a commercial license in order to use Online Forums, and we reply to every post.

Imports OpcLabs.EasySparkplug

Namespace Global.SparkplugDocExamples.Consumer._EasySparkplugConsumer
    Partial Class SubscribeEdgeNodeMetric
        Public Shared Sub CallbackLambda()
            ' Note that the default port for the "mqtt" scheme is 1883.
            Dim hostDescriptor = New SparkplugHostDescriptor("mqtt://localhost")

            ' Instantiate the consumer object.
            Dim consumer = New EasySparkplugConsumer()

            Console.WriteLine("Subscribing...")
            ' The callback is a lambda expression the displays the value
            ' In this example, we specify the precise Sparkplug group ID, edge node ID, and metric name.

            consumer.SubscribeEdgeNodeMetric(hostDescriptor,
                "easyGroup", "easySparkplugDemo", "Random",
                Sub(sender, eventArgs)
                    If (eventArgs.Succeeded) Then
                        If (eventArgs.HasData) Then
                            Console.WriteLine("Value: {0}", eventArgs.MetricData?.Value)
                        End If
                    Else
                        Console.WriteLine("*** Failure: {0}", eventArgs.ErrorMessageBrief)
                    End If
                End Sub)

            Console.WriteLine("Processing notifications for 20 seconds...")
            Threading.Thread.Sleep(20 * 1000)

            Console.WriteLine("Unsubscribing...")
            consumer.UnsubscribeAllMetrics()

            Console.WriteLine("Waiting for 5 seconds...")
            Threading.Thread.Sleep(5 * 1000)

            Console.WriteLine("Finished.")
        End Sub
    End Class
End Namespace
Requirements

Target Platforms: .NET Framework: Windows 10 (selected versions), Windows 11 (selected versions), Windows Server 2016, Windows Server 2022; .NET: Linux, macOS, Microsoft Windows

See Also