QuickOPC User's Guide and Reference
ResolverAccess Event (IEasyUASubscriber)
Example 



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OpcLabs.EasyOpcUA Assembly > OpcLabs.EasyOpc.UA.PubSub Namespace > IEasyUASubscriber Interface : ResolverAccess Event
Raised when the OPC UA PubSub resolver accesses its target.
Syntax
'Declaration
 
Event ResolverAccess As EasyUAResolverAccessEventHandler
 
'Usage
 
Dim instance As IEasyUASubscriber
Dim handler As EasyUAResolverAccessEventHandler
 
AddHandler instance.ResolverAccess, handler
Event Data

The event handler receives an argument of type EasyUAResolverAccessEventArgs containing data related to this event. The following EasyUAResolverAccessEventArgs properties provide information specific to this event.

PropertyDescription
Contains the OpcLabs.BaseLib.ExceptionEventArgs.Exception carried by the event arguments. (Inherited from OpcLabs.BaseLib.ExceptionEventArgs)
Descriptor of the PubSub resolver that has been used.  
Example

.NET

COM

// This example shows how to subscribe to dataset messages and specify a filter, resolving logical parameters to physical
// from an OPC-UA PubSub configuration file in binary format. The metadata obtained through the resolution is used to decode
// fixed layout messages with RawData field encoding.
//
// In order to produce network messages for this example, run the UADemoPublisher tool. For documentation, see
// http://kb.opclabs.com/UADemoPublisher_Basics . In some cases, you may have to specify the interface name to be used.

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 ResolveFromFile()
        {
            // Define the PubSub resolver. We want the information be resolved from a PubSub binary configuration file that
            // we have. The file itself is at the root of the project, and we have specified that it has to be copied to the
            // project's output directory.
            var pubSubResolverDescriptor = UAPubSubResolverDescriptor.File("UADemoPublisher-Default.uabinary");

            // Define the PubSub connection we will work with, using its logical name in the PubSub configuration.
            var pubSubConnectionDescriptor = new UAPubSubConnectionDescriptor { Name = "FixedLayoutConnection" };
            // 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 filter. The writer group and the dataset writer are specified using their logical names in the
            // PubSub configuration. The publisher Id in the filter will be taken from the logical PubSub connection.
            var filter = new UASubscribeDataSetFilter("FixedLayoutGroup", "SimpleWriter");

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

            Console.WriteLine("Subscribing...");
            subscriber.SubscribeDataSet(pubSubResolverDescriptor, pubSubConnectionDescriptor, filter);

            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_ResolveFromFile(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}");
            }
        }

        private static void subscriber_ResolverAccess_ResolveFromFile(object sender, EasyUAResolverAccessEventArgs e)
        {
            // Display resolution information.
            Console.WriteLine(e);
        }

        // Example output:
        //
        //Subscribing...
        //Processing dataset message events for 20 seconds...
        //[PublisherFile: UADemoPublisher-Default.uabinary] (no exception)
        //
        //Dataset data: Good; Data; publisher=(UInt16)30, group=101, fields: 4
        //[BoolToggle, False {System.Boolean}; Good]
        //[Int32, 3072 {System.Int32}; Good]
        //[Int32Fast, 894 {System.Int32}; Good]
        //[DateTime, 10/1/2019 12:21:14 PM {System.DateTime}; Good]
        //
        //Dataset data: Good; Data; publisher=(UInt16)30, group=101, fields: 4
        //[BoolToggle, False {System.Boolean}; Good]
        //[Int32, 3072 {System.Int32}; Good]
        //[Int32Fast, 920 {System.Int32}; Good]
        //[DateTime, 10/1/2019 12:21:14 PM {System.DateTime}; Good]
        //
        //Dataset data: Good; Data; publisher=(UInt16)30, group=101, fields: 4
        //[BoolToggle, False {System.Boolean}; Good]
        //[Int32, 3073 {System.Int32}; Good]
        //[Int32Fast, 1003 {System.Int32}; Good]
        //[DateTime, 10/1/2019 12:21:15 PM {System.DateTime}; Good]
        //
        //Dataset data: Good; Data; publisher=(UInt16)30, group=101, fields: 4
        //[BoolToggle, False {System.Boolean}; Good]
        //[Int32, 3073 {System.Int32}; Good]
        //[Int32Fast, 1074 {System.Int32}; Good]
        //[DateTime, 10/1/2019 12:21:15 PM {System.DateTime}; Good]
        //
        //Dataset data: Good; Data; publisher=(UInt16)30, group=101, fields: 4
        //[BoolToggle, True {System.Boolean}; Good]
        //[Int32, 3074 {System.Int32}; Good]
        //[Int32Fast, 1140 {System.Int32}; Good]
        //[DateTime, 10/1/2019 12:21:16 PM {System.DateTime}; Good]
        //
        //...
    }
}
// This example shows how to subscribe to dataset messages and specify a filter, resolving logical parameters to physical
// from an OPC-UA PubSub configuration file in binary format. The metadata obtained through the resolution is used to decode
// fixed layout messages with RawData field encoding.
//
// In order to produce network messages for this example, run the UADemoPublisher tool. For documentation, see
// http://kb.opclabs.com/UADemoPublisher_Basics . In some cases, you may have to specify the interface name to be used.

type
  TSubscriberEventHandlers81 = class
    procedure OnDataSetMessage(
      ASender: TObject;
      sender: OleVariant;
      const eventArgs: _EasyUADataSetMessageEventArgs);
    procedure OnResolverAccess(
      ASender: TObject;
      sender: OleVariant;
      const eventArgs: _EasyUAResolverAccessEventArgs);
  end;

class procedure SubscribeDataSet.ResolveFromFile;
var
  SubscribeDataSetArguments: _EasyUASubscribeDataSetArguments;
  Subscriber: TEasyUASubscriber;
  SubscriberEventHandlers: TSubscriberEventHandlers81;
begin
  SubscribeDataSetArguments := CoEasyUASubscribeDataSetArguments.Create;

  // Define the PubSub connection we will work with, using its logical name in the PubSub configuration.
  SubscribeDataSetArguments.DataSetSubscriptionDescriptor.ConnectionDescriptor.Name := 'FixedLayoutConnection';
  // 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.
  SubscribeDataSetArguments.DataSetSubscriptionDescriptor.ConnectionDescriptor.ResourceAddress.InterfaceName := 'Ethernet';

  // Define the filter. The writer group and the dataset writer are specified using their logical names in the
  // PubSub configuration. The publisher Id in the filter will be taken from the logical PubSub connection.
  SubscribeDataSetArguments.DataSetSubscriptionDescriptor.Filter.WriterGroupDescriptor.Name := 'FixedLayoutGroup';
  SubscribeDataSetArguments.DataSetSubscriptionDescriptor.Filter.DataSetWriterDescriptor.Name := 'SimpleWriter';

  // Define the PubSub resolver. We want the information be resolved from a PubSub binary configuration file that
  // we have. The file itself is included alongside the script.
  SubscribeDataSetArguments.DataSetSubscriptionDescriptor.ResolverDescriptor.PublisherFileResourceDescriptor.UrlString := 'UADemoPublisher-Default.uabinary';
  SubscribeDataSetArguments.DataSetSubscriptionDescriptor.ResolverDescriptor.ResolverKind := UAPubSubResolverKind_PublisherFile;

  // Instantiate the subscriber object and hook events.
  Subscriber := TEasyUASubscriber.Create(nil);
  SubscriberEventHandlers := TSubscriberEventHandlers81.Create;
  Subscriber.OnDataSetMessage := SubscriberEventHandlers.OnDataSetMessage;
  Subscriber.OnResolverAccess := SubscriberEventHandlers.OnResolverAccess;

  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 TSubscriberEventHandlers81.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;

procedure TSubscriberEventHandlers81.OnResolverAccess(
  ASender: TObject;
  sender: OleVariant;
  const eventArgs: _EasyUAResolverAccessEventArgs);
begin
  // Display resolution information.
  WriteLn(eventArgs.ToString);
end;

// Example output:
//
//Subscribing...
//Processing dataset message events for 20 seconds...
//[PublisherFile: UADemoPublisher-Default.uabinary] (no exception)
//
//Dataset data: Good; Data; publisher=(UInt16)30, group=101, fields: 4
//[BoolToggle, False {System.Boolean}; Good]
//[Int32, 3072 {System.Int32}; Good]
//[Int32Fast, 894 {System.Int32}; Good]
//[DateTime, 10/1/2019 12:21:14 PM {System.DateTime}; Good]
//
//Dataset data: Good; Data; publisher=(UInt16)30, group=101, fields: 4
//[BoolToggle, False {System.Boolean}; Good]
//[Int32, 3072 {System.Int32}; Good]
//[Int32Fast, 920 {System.Int32}; Good]
//[DateTime, 10/1/2019 12:21:14 PM {System.DateTime}; Good]
//
//Dataset data: Good; Data; publisher=(UInt16)30, group=101, fields: 4
//[BoolToggle, False {System.Boolean}; Good]
//[Int32, 3073 {System.Int32}; Good]
//[Int32Fast, 1003 {System.Int32}; Good]
//[DateTime, 10/1/2019 12:21:15 PM {System.DateTime}; Good]
//
//Dataset data: Good; Data; publisher=(UInt16)30, group=101, fields: 4
//[BoolToggle, False {System.Boolean}; Good]
//[Int32, 3073 {System.Int32}; Good]
//[Int32Fast, 1074 {System.Int32}; Good]
//[DateTime, 10/1/2019 12:21:15 PM {System.DateTime}; Good]
//
//Dataset data: Good; Data; publisher=(UInt16)30, group=101, fields: 4
//[BoolToggle, True {System.Boolean}; Good]
//[Int32, 3074 {System.Int32}; Good]
//[Int32Fast, 1140 {System.Int32}; Good]
//[DateTime, 10/1/2019 12:21:16 PM {System.DateTime}; 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