OPC Studio User's Guide and Reference
JsonDataSetReaderMessageParameters Property (_UASubscriberCommunicationParameters)
Example 



OpcLabs.EasyOpcUA Assembly > OpcLabs.EasyOpc.UA.PubSub.ComTypes Namespace > _UASubscriberCommunicationParameters Interface : JsonDataSetReaderMessageParameters Property
Defines JSON message mapping specific dataset reader parameters.
Syntax
'Declaration
 
<CanBeNullAttribute()>
Property JsonDataSetReaderMessageParameters As UAJsonDataSetReaderMessageParameters
'Usage
 
Dim instance As _UASubscriberCommunicationParameters
Dim value As UAJsonDataSetReaderMessageParameters
 
instance.JsonDataSetReaderMessageParameters = value
 
value = instance.JsonDataSetReaderMessageParameters
[CanBeNull()]
UAJsonDataSetReaderMessageParameters JsonDataSetReaderMessageParameters {get; set;}
[CanBeNull()]
property UAJsonDataSetReaderMessageParameters^ JsonDataSetReaderMessageParameters {
   UAJsonDataSetReaderMessageParameters^ get();
   void set (    UAJsonDataSetReaderMessageParameters^ value);
}

Property Value

This value of this property can be null (Nothing in Visual Basic).

Remarks

This member or type is for use from COM. It is not meant to be used from .NET or Python. Refer to the corresponding .NET member or type instead, if you are developing in .NET or Python.

Example
// This example shows how to set parameters specific to JSON message mapping.
//
// 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 C# on GitHub: https://github.com/OPCLabs/Examples-QuickOPC-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 System.Collections.Generic;
using System.Threading;
using OpcLabs.EasyOpc.UA.AddressSpace;
using OpcLabs.EasyOpc.UA.PubSub;
using OpcLabs.EasyOpc.UA.PubSub.Configuration;
using OpcLabs.EasyOpc.UA.PubSub.Engine;
using OpcLabs.EasyOpc.UA.PubSub.OperationModel;

namespace UASubscriberDocExamples.PubSub._EasyUASubscriber
{
    partial class SubscribeDataSet
    {
        public static void MappingParameters()
        {
            // 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.MqttJson;

            // Set a custom property on the PubSub connection that influences how the JSON parsing works. 
            // We are instructing the message parser to turn off the automatic recognition of message format.
            // For more details, see https://kb.opclabs.com/OPC_UA_PubSub_JSON_mapping_component .
            pubSubConnectionDescriptor.CustomPropertyValueDictionary[new UAQualifiedName("{OpcLabs}",
                "OpcLabs.EasyOpc.UA.Toolkit.PubSub.Sdk.JsonReceiveMessageMapping.MessageParsingParameters.AutoRecognizeMessageFormat")] =
                false;

            // Define the arguments for subscribing to the dataset.
            var subscribeDataSetArguments = new UASubscribeDataSetArguments(pubSubConnectionDescriptor)
            {
                DataSetSubscriptionDescriptor =
                {
                    CommunicationParameters =
                    {
                        BrokerDataSetReaderTransportParameters = {QueueName = "opcuademo/json"},
                        // We must set the DataSetFieldContentMask when the format auto-recognition is turned off.
                        DataSetFieldContentMask = UADataSetFieldContentMask.RawData,
                        JsonDataSetReaderMessageParameters =
                        {
                            // We must set the DataSetMessageContentMask when the format auto-recognition is turned off.
                            DataSetMessageContentMask =
                                UAJsonDataSetMessageContentMask.DataSetWriterId |
                                UAJsonDataSetMessageContentMask.SequenceNumber |
                                UAJsonDataSetMessageContentMask.Status,
                            // We must set the NetworkMessageContentMask when the format auto-recognition is turned off.
                            NetworkMessageContentMask =
                                UAJsonNetworkMessageContentMask.NetworkMessageHeader |
                                UAJsonNetworkMessageContentMask.DataSetMessageHeader |
                                UAJsonNetworkMessageContentMask.PublisherId
                        }
                    },
                    Filter =
                    {
                        DataSetWriterDescriptor = 1,
                    }
                }
            };

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

            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_MappingParameters(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=[String]30, writer=1, fields: 4
        //[BoolToggle, True {System.Boolean}; Good]
        //[Int32, 9034 {System.Int64}; Good]
        //[Int32Fast, 1751 {System.Int64}; Good]
        //[DateTime, 1/30/2020 5:23:11 PM {System.DateTime}; Good]
        //
        //Dataset data: Good; Data; publisher=[String]30, writer=1, fields: 4
        //[BoolToggle, True {System.Boolean}; Good]
        //[Int32, 9036 {System.Int64}; Good]
        //[Int32Fast, 2526 {System.Int64}; Good]
        //[DateTime, 1/30/2020 5:23:13 PM {System.DateTime}; Good]
        //...
    }
}
' This example shows how to set parameters specific to JSON message mapping.
'
' 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 VB.NET on GitHub: https://github.com/OPCLabs/Examples-QuickOPC-VBNET .
' 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 Opc.Ua
Imports OpcLabs.EasyOpc.UA.AddressSpace
Imports OpcLabs.EasyOpc.UA.PubSub
Imports OpcLabs.EasyOpc.UA.PubSub.Configuration
Imports OpcLabs.EasyOpc.UA.PubSub.Engine
Imports OpcLabs.EasyOpc.UA.PubSub.OperationModel

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

            ' 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.MqttJson

            ' Set a custom property on the PubSub connection that influences how the JSON parsing works. 
            ' We are instructing the message parser to turn off the automatic recognition of message format.
            ' For more details, see https://kb.opclabs.com/OPC_UA_PubSub_JSON_mapping_component .
            pubSubConnectionDescriptor.CustomPropertyValueDictionary(New UAQualifiedName("{OpcLabs}",
                "OpcLabs.EasyOpc.UA.Toolkit.PubSub.Sdk.JsonReceiveMessageMapping.MessageParsingParameters.AutoRecognizeMessageFormat")) =
                False

            ' Define the arguments for subscribing to the dataset.
            Dim subscribeDataSetArguments = New UASubscribeDataSetArguments(pubSubConnectionDescriptor)
            subscribeDataSetArguments.DataSetSubscriptionDescriptor.CommunicationParameters.BrokerDataSetReaderTransportParameters.QueueName = "opcuademo/json"
            ' We must set the DataSetFieldContentMask when the format auto-recognition is turned off.
            subscribeDataSetArguments.DataSetSubscriptionDescriptor.CommunicationParameters.DataSetFieldContentMask = UADataSetFieldContentMask.RawData
            ' We must set the DataSetMessageContentMask when the format auto-recognition is turned off.
            subscribeDataSetArguments.DataSetSubscriptionDescriptor.CommunicationParameters.JsonDataSetReaderMessageParameters.DataSetMessageContentMask =
                UAJsonDataSetMessageContentMask.DataSetWriterId Or
                UAJsonDataSetMessageContentMask.SequenceNumber Or
                UAJsonDataSetMessageContentMask.Status
            ' We must set the NetworkMessageContentMask when the format auto-recognition is turned off.
            subscribeDataSetArguments.DataSetSubscriptionDescriptor.CommunicationParameters.JsonDataSetReaderMessageParameters.NetworkMessageContentMask =
                UAJsonNetworkMessageContentMask.NetworkMessageHeader Or
                UAJsonNetworkMessageContentMask.DataSetMessageHeader Or
                UAJsonNetworkMessageContentMask.PublisherId
            subscribeDataSetArguments.DataSetSubscriptionDescriptor.Filter.DataSetWriterDescriptor = 1

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

            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_MappingParameters(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=[String]30, writer=1, fields: 4
        '[BoolToggle, True {System.Boolean}; Good]
        '[Int32, 9034 {System.Int64}; Good]
        '[Int32Fast, 1751 {System.Int64}; Good]
        '[DateTime, 1/30/2020 5:23:11 PM {System.DateTime}; Good]
        '
        'Dataset data: Good; Data; publisher=[String]30, writer=1, fields: 4
        '[BoolToggle, True {System.Boolean}; Good]
        '[Int32, 9036 {System.Int64}; Good]
        '[Int32Fast, 2526 {System.Int64}; Good]
        '[DateTime, 1/30/2020 5:23:13 PM {System.DateTime}; Good]
        '...
    End Class
End Namespace
# This example shows how to set parameters specific to JSON message mapping.
#
# 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 .
# 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.
# The QuickOPC package is needed. Install it using "pip install opclabs_quickopc".
import opclabs_quickopc
import opclabs_mqttnet
import time

# Import .NET namespaces.
from OpcLabs.EasyOpc.UA.AddressSpace import *
from OpcLabs.EasyOpc.UA.PubSub import *
from OpcLabs.EasyOpc.UA.PubSub.Configuration 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.MqttJson

# Set a custom property on the PubSub connection that influences how the JSON parsing works.
# We are instructing the message parser to turn off the automatic recognition of message format.
# For more details, see https://kb.opclabs.com/OPC_UA_PubSub_JSON_mapping_component .
pubSubConnectionDescriptor.CustomPropertyValueDictionary.set_Item(
    UAQualifiedName(
        '{OpcLabs}',
        'OpcLabs.EasyOpc.UA.Toolkit.PubSub.Sdk.JsonReceiveMessageMapping.MessageParsingParameters.AutoRecognizeMessageFormat'), False)

# Define the arguments for subscribing to the dataset.
subscribeDataSetArguments = UASubscribeDataSetArguments(pubSubConnectionDescriptor)
subscribeDataSetArguments.DataSetSubscriptionDescriptor.CommunicationParameters.BrokerDataSetReaderTransportParameters.\
    QueueName = 'opcuademo/json'
# We must set the DataSetFieldContentMask when the format auto-recognition is turned off.
subscribeDataSetArguments.DataSetSubscriptionDescriptor.CommunicationParameters.\
    DataSetFieldContentMask = UADataSetFieldContentMask.RawData
# We must set the DataSetMessageContentMask when the format auto-recognition is turned off.
subscribeDataSetArguments.DataSetSubscriptionDescriptor.CommunicationParameters.JsonDataSetReaderMessageParameters.\
    DataSetMessageContentMask =\
        UAJsonDataSetMessageContentMask.DataSetWriterId |\
        UAJsonDataSetMessageContentMask.SequenceNumber |\
        UAJsonDataSetMessageContentMask.Status
# We must set the NetworkMessageContentMask when the format auto-recognition is turned off.
subscribeDataSetArguments.DataSetSubscriptionDescriptor.CommunicationParameters.JsonDataSetReaderMessageParameters.\
    NetworkMessageContentMask =\
        UAJsonNetworkMessageContentMask.NetworkMessageHeader |\
        UAJsonNetworkMessageContentMask.DataSetMessageHeader |\
        UAJsonNetworkMessageContentMask.PublisherId
subscribeDataSetArguments.DataSetSubscriptionDescriptor.Filter.DataSetWriterDescriptor = UADataSetWriterDescriptor(1)

# 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.')
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