Connectivity Software User's Guide and Reference
EasySparkplugConsumer Constructor(SparkplugHostDescriptor)
Example 



OpcLabs.EasySparkplugComponents Assembly > OpcLabs.EasySparkplug Namespace > EasySparkplugConsumer Class > EasySparkplugConsumer Constructor : EasySparkplugConsumer Constructor(SparkplugHostDescriptor)
An implicit host descriptor, used when the host descriptor is not specified explicitly.

The value of this parameter cannot be null (Nothing in Visual Basic).

Initializes a new instance of the class, specifying an implicit host descriptor.
Syntax
'Declaration
 
Public Function New( _
   ByVal implicitHostDescriptor As SparkplugHostDescriptor _
)
'Usage
 
Dim implicitHostDescriptor As SparkplugHostDescriptor
 
Dim instance As New EasySparkplugConsumer(implicitHostDescriptor)
public EasySparkplugConsumer( 
   SparkplugHostDescriptor implicitHostDescriptor
)
public:
EasySparkplugConsumer( 
   SparkplugHostDescriptor^ implicitHostDescriptor
)

Parameters

implicitHostDescriptor
An implicit host descriptor, used when the host descriptor is not specified explicitly.

The value of this parameter cannot be null (Nothing in Visual Basic).

Exceptions
ExceptionDescription

A null reference (Nothing in Visual Basic) is passed to a method that does not accept it as a valid argument.

This is a usage error, i.e. it will never occur (the exception will not be thrown) in a correctly written program. Your code should not catch this exception.

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 specify an implicit host descriptor to be automatically used for subsequent operations on the
// consumer object.
//
// 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
{
    class ImplicitNodeDescriptor
    {
        public static void Main1()
        {
            // Note that the default port for the "mqtt" scheme is 1883.
            var hostDescriptor = new SparkplugHostDescriptor("mqtt://localhost");

            // Instantiate the consumer object and hook events.
            // The implicit host descriptor is specified in the constructor call, and is subsequently used for all
            // operations on this consumer object where the host descriptor is not explicitly specified.
            var consumer = new EasySparkplugConsumer(hostDescriptor);
            consumer.MetricNotification += consumer_Main1_MetricNotification;

            Console.WriteLine("Subscribing...");
            // We are subscribing to two metrics separately, without having to repeat the host descriptor. The implicit
            // host descriptor that was specified in the constructor call is used automatically.
            consumer.SubscribeEdgeNodeMetric("easyGroup", "easySparkplugDemo", "Ramp");
            consumer.SubscribeEdgeNodeMetric("easyGroup", "easySparkplugDemo", "Random");

            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_Main1_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}");
        }
    }
}
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