OPC Studio User's Guide and Reference
MqttUadp Field
Example 



OpcLabs.EasyOpcUA Assembly > OpcLabs.EasyOpc.UA.PubSub.Engine Namespace > UAPubSubTransportProfileUriStrings Class : MqttUadp Field
Transport profile URI string for OPC UA PubSub over Message Queue Telemetry Transport (MQTT) with UADP message mapping.
Syntax
'Declaration
 
Public Const MqttUadp As String
'Usage
 
Dim value As String
 
value = UAPubSubTransportProfileUriStrings.MqttUadp
public const string MqttUadp
public:
const String^ MqttUadp
Example

.NET

// This example shows how to subscribe to all dataset messages on an OPC-UA PubSub connection with MQTT UADP mapping using
// TCP.
//
// The OpcLabs.MqttNet assembly needs to be referenced in your project (or otherwise made available, together with its
// dependencies) for the MQTT transport to work. Refer to the documentation for more information.
//
// Find all latest examples here: https://opclabs.doc-that.com/files/onlinedocs/OPCLabs-OpcStudio/Latest/examples.html .

using System;
using System.Collections.Generic;
using System.Threading;
using OpcLabs.EasyOpc.UA.PubSub;
using OpcLabs.EasyOpc.UA.PubSub.Engine;
using OpcLabs.EasyOpc.UA.PubSub.OperationModel;

namespace UADocExamples.PubSub._EasyUASubscriber
{
    partial class SubscribeDataSet
    {
        public static void MqttUadpTcp()
        {
            // Define the PubSub connection we will work with. Uses implicit conversion from a string.
            // Default port with MQTT is 1883.
            UAPubSubConnectionDescriptor pubSubConnectionDescriptor = "mqtt://opcua-pubsub.demo-this.com";
            // Specify the transport protocol mapping.
            // The statement below isn't actually necessary, due to automatic message mapping recognition feature; see
            // https://kb.opclabs.com/OPC_UA_PubSub_Automatic_Message_Mapping_Recognition for more details.
            pubSubConnectionDescriptor.TransportProfileUriString = UAPubSubTransportProfileUriStrings.MqttUadp;

            // Define the arguments for subscribing to the dataset, specifying the MQTT topic name.
            var subscribeDataSetArguments = new UASubscribeDataSetArguments(pubSubConnectionDescriptor)
            {
                DataSetSubscriptionDescriptor = {CommunicationParameters = {BrokerDataSetReaderTransportParameters =
                {
                    QueueName = "opcuademo/uadp/none"
                }}}
            };

            // Instantiate the subscriber object and hook events.
            var subscriber = new EasyUASubscriber();
            subscriber.DataSetMessage += subscriber_DataSetMessage_MqttUadpTcp;

            Console.WriteLine("Subscribing...");
            subscriber.SubscribeDataSet(subscribeDataSetArguments);

            Console.WriteLine("Processing dataset message events for 20 seconds...");
            Thread.Sleep(20 * 1000);

            Console.WriteLine("Unsubscribing...");
            subscriber.UnsubscribeAllDataSets();

            Console.WriteLine("Waiting for 1 second...");
            // Unsubscribe operation is asynchronous, messages may still come for a short while.
            Thread.Sleep(1 * 1000);

            Console.WriteLine("Finished.");
        }

        static void subscriber_DataSetMessage_MqttUadpTcp(object sender, EasyUADataSetMessageEventArgs e)
        {
            // Display the dataset.
            if (e.Succeeded)
            {
                // An event with null DataSetData just indicates a successful connection.
                if (!(e.DataSetData is null))
                {
                    Console.WriteLine();
                    Console.WriteLine($"Dataset data: {e.DataSetData}");
                    foreach (KeyValuePair<string, UADataSetFieldData> pair in e.DataSetData.FieldDataDictionary)
                        Console.WriteLine(pair);
                }
            }
            else
            {
                Console.WriteLine();
                Console.WriteLine($"*** Failure: {e.ErrorMessage}");
            }
        }

        // Example output:
        //
        //Subscribing...
        //Processing dataset message events for 20 seconds...
        //
        //Dataset data: Good; Data; publisher="32", writer=1, class=eae79794-1af7-4f96-8401-4096cd1d8908, fields: 4
        //[#0, False {System.Boolean}; Good]
        //[#1, 6685 {System.Int32}; Good]
        //[#2, 1444 {System.Int32}; Good]
        //[#3, 1/4/2020 6:06:20 PM {System.DateTime}; Good]
        //
        //Dataset data: Good; Data; publisher="32", writer=3, class=96976b7b-0db7-46c3-a715-0979884b55ae, fields: 100
        //[#0, 85 {System.Int64}; Good]
        //[#1, 185 {System.Int64}; Good]
        //[#2, 285 {System.Int64}; Good]
        //[#3, 385 {System.Int64}; Good]
        //[#4, 485 {System.Int64}; Good]
        //[#5, 585 {System.Int64}; Good]
        //[#6, 685 {System.Int64}; Good]
        //[#7, 785 {System.Int64}; Good]
        //[#8, 885 {System.Int64}; Good]
        //[#9, 985 {System.Int64}; Good]
        //[#10, 1085 {System.Int64}; Good]
        //...
    }
}
# This example shows how to subscribe to all dataset messages on an OPC-UA PubSub connection with MQTT UADP mapping
# using TCP.
#
# The following package needs to be referenced in your project (or otherwise made available) for the MQTT transport to
# work.
# - OpcLabs.MqttNet
# Refer to the documentation for more information.
#
# Find all latest examples here: https://opclabs.doc-that.com/files/onlinedocs/OPCLabs-OpcStudio/Latest/examples.html .
# OPC client and subscriber examples in Python on GitHub: https://github.com/OPCLabs/Examples-QuickOPC-Python .
# The QuickOPC package is needed. Install it using "pip install opclabs_quickopc".
import opclabs_quickopc
import time

# Import .NET namespaces.
from OpcLabs.EasyOpc.UA.PubSub import *
from OpcLabs.EasyOpc.UA.PubSub.Engine import *
from OpcLabs.EasyOpc.UA.PubSub.OperationModel import *


def dataSetMessage(sender, e):
    # Display the dataset.
    if e.Succeeded:
        # An event with null DataSetData just indicates a successful connection.
        if e.DataSetData is not None:
            print('')
            print('Dataset data: ', e.DataSetData, sep='')
            for pair in e.DataSetData.FieldDataDictionary:
                print(pair)
    else:
        print('')
        print('*** Failure: ', e.ErrorMessageBrief, sep='')


# Define the PubSub connection we will work with. Uses implicit conversion from a string.
# Default port with MQTT is 1883.
pubSubConnectionDescriptor = UAPubSubConnectionDescriptor.op_Implicit('mqtt://opcua-pubsub.demo-this.com')
# Specify the transport protocol mapping.
# The statement below isn't actually necessary, due to automatic message mapping recognition feature; see
# https://kb.opclabs.com/OPC_UA_PubSub_Automatic_Message_Mapping_Recognition for more details.
pubSubConnectionDescriptor.TransportProfileUriString = UAPubSubTransportProfileUriStrings.MqttUadp

# Define the arguments for subscribing to the dataset, specifying the MQTT topic name.
subscribeDataSetArguments = UASubscribeDataSetArguments(pubSubConnectionDescriptor)
subscribeDataSetArguments.DataSetSubscriptionDescriptor.CommunicationParameters.BrokerDataSetReaderTransportParameters.\
    QueueName = 'opcuademo/uadp/none'

# Instantiate the subscriber object and hook events.
subscriber = EasyUASubscriber()
subscriber.DataSetMessage += dataSetMessage

print('Subscribing...')
IEasyUASubscriberExtension.SubscribeDataSet(subscriber, subscribeDataSetArguments)

print('Processing dataset message events for 20 seconds...')
time.sleep(20)

print('Unsubscribing...')
subscriber.UnsubscribeAllDataSets()

print('Waiting for 1 second...')
# Unsubscribe operation is asynchronous, messages may still come for a short while.
time.sleep(1)

subscriber.DataSetMessage -= dataSetMessage

print('Finished.')
' This example shows how to subscribe to all dataset messages on an OPC-UA PubSub connection with MQTT UADP mapping using
' TCP.
'
' The OpcLabs.MqttNet assembly needs to be referenced in your project (or otherwise made available, together with its
' dependencies) for the MQTT transport to work. Refer to the documentation for more information.
'
' Find all latest examples here: https://opclabs.doc-that.com/files/onlinedocs/OPCLabs-OpcStudio/Latest/examples.html .

Imports OpcLabs.EasyOpc.UA.PubSub
Imports OpcLabs.EasyOpc.UA.PubSub.Engine
Imports OpcLabs.EasyOpc.UA.PubSub.OperationModel

Namespace PubSub._EasyUASubscriber
    Partial Friend Class SubscribeDataSet
        Public Shared Sub MqttUadpTcp()

            ' Define the PubSub connection we will work with. Uses implicit conversion from a string.
            ' Default port with MQTT is 1883.
            Dim pubSubConnectionDescriptor As UAPubSubConnectionDescriptor = "mqtt://opcua-pubsub.demo-this.com"
            ' Specify the transport protocol mapping.
            ' The statement below isn't actually necessary, due to automatic message mapping recognition feature; see
            ' https://kb.opclabs.com/OPC_UA_PubSub_Automatic_Message_Mapping_Recognition for more details.
            pubSubConnectionDescriptor.TransportProfileUriString = UAPubSubTransportProfileUriStrings.MqttUadp

            ' Define the arguments for subscribing to the dataset, specifying the MQTT topic name.
            Dim subscribeDataSetArguments = New UASubscribeDataSetArguments(pubSubConnectionDescriptor)
            subscribeDataSetArguments.DataSetSubscriptionDescriptor.CommunicationParameters.BrokerDataSetReaderTransportParameters.QueueName = "opcuademo/uadp/none"

            ' Instantiate the subscriber object and hook events.
            Dim subscriber = New EasyUASubscriber()
            AddHandler subscriber.DataSetMessage, AddressOf subscriber_DataSetMessage_MqttUadpTcp

            Console.WriteLine("Subscribing...")
            subscriber.SubscribeDataSet(subscribeDataSetArguments)

            Console.WriteLine("Processing dataset message events for 20 seconds...")
            Threading.Thread.Sleep(20 * 1000)

            Console.WriteLine("Unsubscribing...")
            subscriber.UnsubscribeAllDataSets()

            Console.WriteLine("Waiting for 1 second...")
            ' Unsubscribe operation is asynchronous, messages may still come for a short while.
            Threading.Thread.Sleep(1 * 1000)

            Console.WriteLine("Finished...")
        End Sub

        Private Shared Sub subscriber_DataSetMessage_MqttUadpTcp(ByVal sender As Object, ByVal e As EasyUADataSetMessageEventArgs)
            ' Display the dataset.
            If e.Succeeded Then
                ' An event with null DataSetData just indicates a successful connection.
                If e.DataSetData IsNot Nothing Then
                    Console.WriteLine()
                    Console.WriteLine($"Dataset data: {e.DataSetData}")
                    For Each pair As KeyValuePair(Of String, UADataSetFieldData) In e.DataSetData.FieldDataDictionary
                        Console.WriteLine(pair)
                    Next
                End If
            Else
                Console.WriteLine()
                Console.WriteLine($"*** Failure: {e.ErrorMessage}")
            End If
        End Sub

        ' Example output:
        '
        'Subscribing...
        'Processing dataset message events for 20 seconds...
        '
        'Dataset data: Good; Data; publisher="32", writer=1, class=eae79794-1af7-4f96-8401-4096cd1d8908, fields: 4
        '[#0, False {System.Boolean}; Good]
        '[#1, 6685 {System.Int32}; Good]
        '[#2, 1444 {System.Int32}; Good]
        '[#3, 1/4/2020 6:06:20 PM {System.DateTime}; Good]
        '
        'Dataset data: Good; Data; publisher="32", writer=3, class=96976b7b-0db7-46c3-a715-0979884b55ae, fields: 100
        '[#0, 85 {System.Int64}; Good]
        '[#1, 185 {System.Int64}; Good]
        '[#2, 285 {System.Int64}; Good]
        '[#3, 385 {System.Int64}; Good]
        '[#4, 485 {System.Int64}; Good]
        '[#5, 585 {System.Int64}; Good]
        '[#6, 685 {System.Int64}; Good]
        '[#7, 785 {System.Int64}; Good]
        '[#8, 885 {System.Int64}; Good]
        '[#9, 985 {System.Int64}; Good]
        '[#10, 1085 {System.Int64}; Good]
        '...
    End Class
End Namespace
Remarks

Profile author: OPC Foundation

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