OPC Studio User's Guide and Reference
SubscribeDataSet Method (EasyUASubscriberCore)
Example 



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OpcLabs.EasyOpcUA Assembly > OpcLabs.EasyOpc.UA.PubSub Namespace > EasyUASubscriberCore Class : SubscribeDataSet Method
Holds all arguments needed to subscribe to a dataset in OPC UA PubSub.
Subscribes to a dataset. The DataSetMessage event is generated for each dataset message received.
Syntax
'Declaration
 
Public Function SubscribeDataSet( _
   ByVal subscribeDataSetArguments As EasyUASubscribeDataSetArguments _
) As Integer
 
'Usage
 
Dim instance As EasyUASubscriberCore
Dim subscribeDataSetArguments As EasyUASubscribeDataSetArguments
Dim value As Integer
 
value = instance.SubscribeDataSet(subscribeDataSetArguments)

Parameters

subscribeDataSetArguments
Holds all arguments needed to subscribe to a dataset in OPC UA PubSub.

Return Value

Returns a dataset subscription handle that can be used to change the subscription, obtain its arguments, or unsubscribe.
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

 

This method operates (at least in part) asynchronously, with respect to the caller. The actual execution of the operation may be delayed, and the outcome of the operation (if any) is provided to the calling code using an event notification, callback, or other means explained in the text. In a properly written program, this method does not throw any exceptions. You should therefore not put try/catch statements or similar constructs around calls to this method. The only exceptions thrown by this method are for usage errors, i.e. when your code violates the usage contract of the method, such as passing in invalid arguments or calling the method when the state of the object does not allow it. Any operation-related errors (i.e. errors that depend on external conditions that your code cannot reliably check) are indicated by the means the operation returns its outcome (if any), which is described in the text. For more information, see Do not catch any exceptions with asynchronous or multiple-operation methods.
Example

.NET

COM

// This example shows how to subscribe to all dataset messages with specific publisher Id, on an OPC-UA PubSub connection
// with UDP UADP mapping.
//
// In order to produce network messages for this example, run the UADemoPublisher tool. For documentation, see
// https://kb.opclabs.com/UADemoPublisher_Basics . In some cases, you may have to specify the interface name to be used.
//
// 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.OperationModel;

namespace UADocExamples.PubSub._EasyUASubscriber
{
    partial class SubscribeDataSet
    {
        public static void PublisherId()
        {
            // Define the PubSub connection we will work with. Uses implicit conversion from a string.
            UAPubSubConnectionDescriptor pubSubConnectionDescriptor = "opc.udp://239.0.0.1";
            // In some cases you may have to set the interface (network adapter) name that needs to be used, similarly to
            // the statement below. Your actual interface name may differ, of course.
            //pubSubConnectionDescriptor.ResourceAddress.InterfaceName = "Ethernet";

            // Define the arguments for subscribing to the dataset, where the filter is (unsigned 64-bit) publisher Id 31.
            var subscribeDataSetArguments = new UASubscribeDataSetArguments(
                pubSubConnectionDescriptor, UAPublisherId.CreateUInt64(31));

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

            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_PublisherId(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.ErrorMessageBrief}");
            }
        }

        // Example output:
        //
        //Subscribing...
        //Processing dataset message events for 20 seconds...
        //
        //Dataset data: Good; Event; publisher=(UInt64)31, writer=51, fields: 4
        //[#0, True {System.Boolean}; Good]
        //[#1, 1237 {System.Int32}; Good]
        //[#2, 2514 {System.Int32}; Good]
        //[#3, 10/1/2019 9:03:59 AM {System.DateTime}; Good]
        //
        //Dataset data: Good; Data; publisher=(UInt64)31, writer=1, fields: 4
        //[#0, False {System.Boolean}; Good]
        //[#1, 1239 {System.Int32}; Good]
        //[#2, 2703 {System.Int32}; Good]
        //[#3, 10/1/2019 9:04:01 AM {System.DateTime}; Good]
        //
        //Dataset data: Good; Data; publisher=(UInt64)31, writer=4, fields: 16
        //[#0, False {System.Boolean}; Good]
        //[#1, 215 {System.Byte}; Good]
        //[#2, 1239 {System.Int16}; Good]
        //[#3, 1239 {System.Int32}; Good]
        //[#4, 1239 {System.Int64}; Good]
        //[#5, 87 {System.Int16}; Good]
        //[#6, 1239 {System.Int32}; Good]
        //[#7, 1239 {System.Int64}; Good]
        //[#8, 1239 {System.Decimal}; Good]
        //[#9, 1239 {System.Single}; Good]
        //[#10, 1239 {System.Double}; Good]
        //[#11, Romeo {System.String}; Good]
        //[#12, [20] {175, 186, 248, 246, 215, ...} {System.Byte[]}; Good]
        //[#13, d4492ca8-35c8-4b98-8edf-6ffa5ca041ca {System.Guid}; Good]
        //[#14, 10/1/2019 9:04:01 AM {System.DateTime}; Good]
        //[#15, [10] {1239, 1240, 1241, 1242, 1243, ...} {System.Int64[]}; Good]
        //
        //Dataset data: Good; Data; publisher=(UInt64)31, writer=1, fields: 4
        //[#2, 2722 {System.Int32}; Good]
        //[#3, 10/1/2019 9:04:01 AM {System.DateTime}; Good]
        //[#0, False {System.Boolean}; Good]
        //[#1, 1239 {System.Int32}; Good]
        //
        //Dataset data: Good; Data; publisher=(UInt64)31, writer=3, fields: 100
        //[#0, 39 {System.Int64}; Good]
        //[#1, 139 {System.Int64}; Good]
        //[#2, 239 {System.Int64}; Good]
        //[#3, 339 {System.Int64}; Good]
        //[#4, 439 {System.Int64}; Good]
        //[#5, 539 {System.Int64}; Good]
        //[#6, 639 {System.Int64}; Good]
        //[#7, 739 {System.Int64}; Good]
        //[#8, 839 {System.Int64}; Good]
        //[#9, 939 {System.Int64}; Good]
        //[#10, 1039 {System.Int64}; Good]
        //...
    }
}
// This example shows how to subscribe to all dataset messages with specific publisher Id, on an OPC-UA PubSub connection
// with UDP UADP mapping.
//
// In order to produce network messages for this example, run the UADemoPublisher tool. For documentation, see
// https://kb.opclabs.com/UADemoPublisher_Basics . In some cases, you may have to specify the interface name to be used.
//
// Find all latest examples here : https://opclabs.doc-that.com/files/onlinedocs/OPCLabs-OpcStudio/Latest/examples.html .

type
  TSubscriberEventHandlers80 = class
    procedure OnDataSetMessage(
      ASender: TObject;
      sender: OleVariant;
      const eventArgs: _EasyUADataSetMessageEventArgs);
  end;

class procedure SubscribeDataSet.PublisherId;
var
  ConnectionDescriptor: _UAPubSubConnectionDescriptor;
  SubscribeDataSetArguments: _EasyUASubscribeDataSetArguments;
  Subscriber: TEasyUASubscriber;
  SubscriberEventHandlers: TSubscriberEventHandlers80;
begin
  // Define the PubSub connection we will work with.
  SubscribeDataSetArguments := CoEasyUASubscribeDataSetArguments.Create;
  ConnectionDescriptor := SubscribeDataSetArguments.DataSetSubscriptionDescriptor.ConnectionDescriptor;
  ConnectionDescriptor.ResourceAddress.ResourceDescriptor.UrlString := 'opc.udp://239.0.0.1';
  // In some cases you may have to set the interface (network adapter) name that needs to be used, similarly to
  // the statement below. Your actual interface name may differ, of course.
  //ConnectionDescriptor.ResourceAddress.InterfaceName := 'Ethernet';

  // Define the arguments for subscribing to the dataset, where the filter is (unsigned 64-bit) publisher Id 31.
  SubscribeDataSetArguments.DataSetSubscriptionDescriptor.Filter.PublisherId.SetIdentifier(UAPublisherIdType_UInt64, 31);

  // Instantiate the subscriber object and hook events.
  Subscriber := TEasyUASubscriber.Create(nil);
  SubscriberEventHandlers := TSubscriberEventHandlers80.Create;
  Subscriber.OnDataSetMessage := SubscriberEventHandlers.OnDataSetMessage;

  WriteLn('Subscribing...');
  Subscriber.SubscribeDataSet(SubscribeDataSetArguments);

  WriteLn('Processing dataset message for 20 seconds...');
  PumpSleep(20*1000);

  WriteLn('Unsubscribing...');
  Subscriber.UnsubscribeAllDataSets;

  WriteLn('Waiting for 1 second...');
  // Unsubscribe operation is asynchronous, messages may still come for a short while.
  PumpSleep(1*1000);

  WriteLn('Finished.');
  FreeAndNil(Subscriber);
  FreeAndNil(SubscriberEventHandlers);
end;

procedure TSubscriberEventHandlers80.OnDataSetMessage(
  ASender: TObject;
  sender: OleVariant;
  const eventArgs: _EasyUADataSetMessageEventArgs);
var
  Count: Cardinal;
  DictionaryEntry2: _DictionaryEntry2;
  Element: OleVariant;
  FieldDataDictionaryEnumerator: IEnumVariant;
begin
  // Display the dataset.
  if eventArgs.Succeeded then
  begin
    // An event with null DataSetData just indicates a successful connection.
    if eventArgs.DataSetData <> nil then
    begin
      WriteLn;
      WriteLn('Dataset data: ', eventArgs.DataSetData.ToString);
      FieldDataDictionaryEnumerator := eventArgs.DataSetData.FieldDataDictionary.GetEnumerator;
      while (FieldDataDictionaryEnumerator.Next(1, Element, Count) = S_OK) do
      begin
        DictionaryEntry2 := IUnknown(Element) as _DictionaryEntry2;
        WriteLn(DictionaryEntry2.ToString);
      end;
    end;
  end
  else begin
    WriteLn;
      WriteLn('*** Failure: ', eventArgs.ErrorMessageBrief);
  end;
end;

// Example output:
//
//Subscribing...
//Processing dataset message events for 20 seconds...
//
//Dataset data: Good; Event; publisher=(UInt64)31, writer=51, fields: 4
//[#0, True {System.Boolean}; Good]
//[#1, 1237 {System.Int32}; Good]
//[#2, 2514 {System.Int32}; Good]
//[#3, 10/1/2019 9:03:59 AM {System.DateTime}; Good]
//
//Dataset data: Good; Data; publisher=(UInt64)31, writer=1, fields: 4
//[#0, False {System.Boolean}; Good]
//[#1, 1239 {System.Int32}; Good]
//[#2, 2703 {System.Int32}; Good]
//[#3, 10/1/2019 9:04:01 AM {System.DateTime}; Good]
//
//Dataset data: Good; Data; publisher=(UInt64)31, writer=4, fields: 16
//[#0, False {System.Boolean}; Good]
//[#1, 215 {System.Byte}; Good]
//[#2, 1239 {System.Int16}; Good]
//[#3, 1239 {System.Int32}; Good]
//[#4, 1239 {System.Int64}; Good]
//[#5, 87 {System.Int16}; Good]
//[#6, 1239 {System.Int32}; Good]
//[#7, 1239 {System.Int64}; Good]
//[#8, 1239 {System.Decimal}; Good]
//[#9, 1239 {System.Single}; Good]
//[#10, 1239 {System.Double}; Good]
//[#11, Romeo {System.String}; Good]
//[#12, [20] {175, 186, 248, 246, 215, ...} {System.Byte[]}; Good]
//[#13, d4492ca8-35c8-4b98-8edf-6ffa5ca041ca {System.Guid}; Good]
//[#14, 10/1/2019 9:04:01 AM {System.DateTime}; Good]
//[#15, [10] {1239, 1240, 1241, 1242, 1243, ...} {System.Int64[]}; Good]
//
//Dataset data: Good; Data; publisher=(UInt64)31, writer=1, fields: 4
//[#2, 2722 {System.Int32}; Good]
//[#3, 10/1/2019 9:04:01 AM {System.DateTime}; Good]
//[#0, False {System.Boolean}; Good]
//[#1, 1239 {System.Int32}; Good]
//
//Dataset data: Good; Data; publisher=(UInt64)31, writer=3, fields: 100
//[#0, 39 {System.Int64}; Good]
//[#1, 139 {System.Int64}; Good]
//[#2, 239 {System.Int64}; Good]
//[#3, 339 {System.Int64}; Good]
//[#4, 439 {System.Int64}; Good]
//[#5, 539 {System.Int64}; Good]
//[#6, 639 {System.Int64}; Good]
//[#7, 739 {System.Int64}; Good]
//[#8, 839 {System.Int64}; Good]
//[#9, 939 {System.Int64}; Good]
//[#10, 1039 {System.Int64}; Good]
//...
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