QuickOPC User's Guide and Reference
JsonDataSetReaderMessageParameters Property (UASubscriberCommunicationParameters)
Example 



OpcLabs.EasyOpcUA Assembly > OpcLabs.EasyOpc.UA.PubSub Namespace > UASubscriberCommunicationParameters Class : JsonDataSetReaderMessageParameters Property
Defines JSON message mapping specific dataset reader parameters.
Syntax
'Declaration
 
<NullableAttribute()>
Public Property JsonDataSetReaderMessageParameters As UAJsonDataSetReaderMessageParameters
'Usage
 
Dim instance As UASubscriberCommunicationParameters
Dim value As UAJsonDataSetReaderMessageParameters
 
instance.JsonDataSetReaderMessageParameters = value
 
value = instance.JsonDataSetReaderMessageParameters
[Nullable()]
public UAJsonDataSetReaderMessageParameters JsonDataSetReaderMessageParameters {get; set;}
[Nullable()]
public:
property UAJsonDataSetReaderMessageParameters^ JsonDataSetReaderMessageParameters {
   UAJsonDataSetReaderMessageParameters^ get();
   void set (    UAJsonDataSetReaderMessageParameters^ value);
}
Example

.NET

// 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.

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 UADocExamples.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.

# 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