Connectivity Software User's Guide and Reference
SparkplugConnectionDescriptor Class
Members  Example 



OpcLabs.EasySparkplug Assembly > OpcLabs.EasySparkplug Namespace : SparkplugConnectionDescriptor Class
Represents a descriptor for a connection in the Sparkplug system.
Object Model
SparkplugConnectionDescriptor ClassSparkplugBrokerDescriptor ClassSparkplugConnectionDescriptor Class
Syntax
'Declaration
 
<ExceptionContractAnnotationAttribute(True)>
<CLSCompliantAttribute(True)>
<TypeConverterAttribute(System.ComponentModel.ExpandableObjectConverter)>
<ValueControlAttribute("OpcLabs.BaseLib.Forms.Common.ObjectSerializationControl, OpcLabs.BaseLibForms, Version=5.83.473.1, Culture=neutral, PublicKeyToken=6faddca41dacb409", 
   DefaultReadWrite=False, 
   Export=True, 
   PageId=10001)>
<SerializableAttribute()>
Public Class SparkplugConnectionDescriptor 
   Inherits OpcLabs.BaseLib.Info
   Implements LINQPad.ICustomMemberProvider, OpcLabs.BaseLib.ComTypes._Info, OpcLabs.BaseLib.ComTypes._Object2, System.ICloneable, System.Runtime.Serialization.ISerializable, System.Xml.Serialization.IXmlSerializable 
'Usage
 
Dim instance As SparkplugConnectionDescriptor
[ExceptionContractAnnotation(true)]
[CLSCompliant(true)]
[TypeConverter(System.ComponentModel.ExpandableObjectConverter)]
[ValueControl("OpcLabs.BaseLib.Forms.Common.ObjectSerializationControl, OpcLabs.BaseLibForms, Version=5.83.473.1, Culture=neutral, PublicKeyToken=6faddca41dacb409", 
   DefaultReadWrite=false, 
   Export=true, 
   PageId=10001)]
[Serializable()]
public class SparkplugConnectionDescriptor : OpcLabs.BaseLib.Info, LINQPad.ICustomMemberProvider, OpcLabs.BaseLib.ComTypes._Info, OpcLabs.BaseLib.ComTypes._Object2, System.ICloneable, System.Runtime.Serialization.ISerializable, System.Xml.Serialization.IXmlSerializable  
[ExceptionContractAnnotation(true)]
[CLSCompliant(true)]
[TypeConverter(System.ComponentModel.ExpandableObjectConverter)]
[ValueControl("OpcLabs.BaseLib.Forms.Common.ObjectSerializationControl, OpcLabs.BaseLibForms, Version=5.83.473.1, Culture=neutral, PublicKeyToken=6faddca41dacb409", 
   DefaultReadWrite=false, 
   Export=true, 
   PageId=10001)]
[Serializable()]
public ref class SparkplugConnectionDescriptor : public OpcLabs.BaseLib.Info, LINQPad.ICustomMemberProvider, OpcLabs.BaseLib.ComTypes._Info, OpcLabs.BaseLib.ComTypes._Object2, System.ICloneable, System.Runtime.Serialization.ISerializable, System.Xml.Serialization.IXmlSerializable  
Remarks

Sparkplug connection descriptor is used both with the Sparkplug consumer model (EasySparkplugConsumerCore) and with the Sparkplug provider model ().

The Sparkplug connection descriptor contains a Sparkplug broker descriptor (which usually specifies an MQTT broker to connect to), and a client ID to be used for the MQTT connection.

The Sparkplug specification also describes scenarios in which multiple Sparkplug brokers are used in conjunction. The Sparkplug connection descriptor is a higher-level abstraction than just the Sparkplug broker descriptor, because it allows for such advanced scenarios (although they may not be supported by the software currently).

There is an implicit conversion to the SparkplugConnectionDescriptor class from the SparkplugBrokerDescriptor class, which means that (in languages that support implicit conversions, such as C# or VB.NET), you can conveniently use a Sparkplug broker descriptor in place of the connection descriptor, which makes the distinction between them almost invisible in many cases.

 

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, specifying an MQTT client ID.
//
// 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 ClientId()
        {
            // The MQTT client ID can be specified in the connection descriptor. When empty (the default), the component
            // generates a unique, semi-random client ID.
            // Note that the default port for the "mqtt" scheme is 1883.
            var hostDescriptor = new SparkplugHostDescriptor("mqtt://localhost")
            {
                ConnectionDescriptor =
                {
                    ClientId = "myApplication"
                }
            };

            // Alternatively, the MQTT client ID can be specified in the broker URL using the "clientId" query parameter,
            // as below.
            var hostDescriptor2 = new SparkplugHostDescriptor("mqtt://localhost?clientId=myApplication");

            // Instantiate the consumer object and hook events.
            var consumer = new EasySparkplugConsumer();
            consumer.MetricNotification += consumer_ClientId_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,    // or hostDescriptor2, if you prefer the alternative method
                "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_ClientId_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, specifying an MQTT client ID.
'
' 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 ClientId()
            ' The MQTT client ID can be specified in the connection descriptor. When empty (the default), the component
            ' generates a unique, semi-random client ID.
            ' Note that the default port for the "mqtt" scheme is 1883.
            Dim hostDescriptor = New SparkplugHostDescriptor("mqtt://localhost")
            hostDescriptor.ConnectionDescriptor.ClientId = "myApplication"

            ' Alternatively, the MQTT client ID can be specified in the broker URL using the "clientId" query parameter,
            ' as below.
            Dim hostDescriptor2 = New SparkplugHostDescriptor("mqtt://localhost?clientId=myApplication")

            ' Instantiate the consumer object and hook events.
            Dim consumer = New EasySparkplugConsumer()
            AddHandler consumer.MetricNotification, AddressOf consumer_ClientId_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, ' or hostDescriptor2, if you prefer the alternative method
                "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_ClientId_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 create a Sparkplug edge node with a single metric, start and stop it, specifying an MQTT
// client ID.
//
// You can use any Sparkplug application, including our SparkplugCmd utility and the SparkplugApplicationConsoleDemo
// program, to subscribe to the edge node data. 
//
// 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.EdgeNode._EasySparkplugEdgeNode
{
    partial class Start_Stop
    {
        static public void ClientId()
        {
            // The MQTT client ID can be specified in the connection descriptor. When empty (the default), the component
            // generates a unique, semi-random client ID.
            // Note that the default port for the "mqtt" scheme is 1883.
            var hostDescriptor = new SparkplugHostDescriptor("mqtt://localhost")
            {
                ConnectionDescriptor =
                {
                    ClientId = "myApplication"
                }
            };

            // Alternatively, the MQTT client ID can be specified in the broker URL using the "clientId" query parameter,
            // as below.
            var hostDescriptor2 = new SparkplugHostDescriptor("mqtt://localhost?clientId=myApplication");

            // Instantiate the edge node object and hook events.
            var edgeNode = new EasySparkplugEdgeNode(hostDescriptor,    // or hostDescriptor2, if you prefer the alternative method
                "easyGroup", "easySparkplugDemo");
            edgeNode.SystemConnectionStateChanged += edgeNode_ClientId_SystemConnectionStateChanged;

            // Define a metric providing random integers.
            var random = new Random();
            edgeNode.Metrics.Add(new SparkplugMetric("MyMetric").ReadValueFunction(() => random.Next()));

            // Start the edge node.
            Console.WriteLine("The edge node is starting...");
            edgeNode.Start();

            Console.WriteLine("The edge node is started.");
            Console.WriteLine();

            // Let the user decide when to stop.
            Console.WriteLine("Press Enter to stop the edge node...");
            Console.ReadLine();

            // Stop the edge node.
            Console.WriteLine("The edge node is stopping...");
            edgeNode.Stop();

            Console.WriteLine("The edge node is stopped.");
        }


        static void edgeNode_ClientId_SystemConnectionStateChanged(
            object sender, 
            SparkplugConnectionStateChangedEventArgs eventArgs)
        {
            // Display the new connection state (such as when the connection to the broker succeeds or fails).
            Console.WriteLine($"{nameof(EasySparkplugEdgeNode.SystemConnectionStateChanged)}: {eventArgs}");
        }
    }
}
' This example shows how to create a Sparkplug edge node with a single metric, start and stop it, specifying an MQTT
' client ID.
'
' You can use any Sparkplug application, including our SparkplugCmd utility and the SparkplugApplicationConsoleDemo
' program, to subscribe to the edge node data.
'
' 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.EdgeNode._EasySparkplugEdgeNode
    Partial Class Start_Stop
        Public Shared Sub ClientId()
            ' The MQTT client ID can be specified in the connection descriptor. When empty (the default), the component
            ' generates a unique, semi-random client ID.
            ' Note that the default port for the "mqtt" scheme is 1883.
            Dim hostDescriptor = New SparkplugHostDescriptor("mqtt://localhost")
            hostDescriptor.ConnectionDescriptor.ClientId = "myApplication"

            ' Alternatively, the MQTT client ID can be specified in the broker URL using the "clientId" query parameter,
            ' as below.
            Dim hostDescriptor2 = New SparkplugHostDescriptor("mqtt://localhost?clientId=myApplication")

            ' Instantiate the edge node object and hook events.
            Dim edgeNode = New EasySparkplugEdgeNode(hostDescriptor, ' or hostDescriptor2, if you prefer the alternative method
                                                     "easyGroup", "easySparkplugDemo")
            AddHandler edgeNode.SystemConnectionStateChanged, AddressOf edgeNode_ClientId_SystemConnectionStateChanged

            ' Define a metric providing random integers.
            Dim random = New Random()
            edgeNode.Metrics.Add(New SparkplugMetric("MyMetric").ReadValueFunction(Function() random.Next()))

            ' Start the edge node.
            Console.WriteLine("The edge node is starting...")
            edgeNode.Start()

            Console.WriteLine("The edge node is started.")
            Console.WriteLine()

            ' Let the user decide when to stop.
            Console.WriteLine("Press Enter to stop the edge node...")
            Console.ReadLine()

            ' Stop the edge node.
            Console.WriteLine("The edge node is stopping...")
            edgeNode.Stop()

            Console.WriteLine("The edge node is stopped.")
        End Sub

        Private Shared Sub edgeNode_ClientId_SystemConnectionStateChanged _
            (ByVal sender As Object, ByVal eventArgs As SparkplugConnectionStateChangedEventArgs)
            ' Display the new connection state (such as when the connection to the broker succeeds or fails).
            Console.WriteLine($"{NameOf(EasySparkplugEdgeNode.SystemConnectionStateChanged)}: {eventArgs}")
        End Sub
    End Class
End Namespace
Inheritance Hierarchy

System.Object
   OpcLabs.BaseLib.Object2
      OpcLabs.BaseLib.Info
         OpcLabs.EasySparkplug.SparkplugConnectionDescriptor

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