OPC Studio User's Guide and Reference
PullEventNotificationQueueCapacity Property (EasyUAClientCore)
Example 



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OpcLabs.EasyOpcUA Assembly > OpcLabs.EasyOpc.UA Namespace > EasyUAClientCore Class : PullEventNotificationQueueCapacity Property
Capacity of the event pull queue for event notifications.
Syntax
'Declaration
 
<DefaultValueAttribute(0)>
Public Property PullEventNotificationQueueCapacity As Integer
 
'Usage
 
Dim instance As EasyUAClientCore
Dim value As Integer
 
instance.PullEventNotificationQueueCapacity = value
 
value = instance.PullEventNotificationQueueCapacity
Example

.NET

COM

// This example shows how to subscribe to event notifications, pull events, and display each incoming event.
//
// Find all latest examples here: https://opclabs.doc-that.com/files/onlinedocs/OPCLabs-OpcStudio/Latest/examples.html .

using System;
using OpcLabs.EasyOpc.UA;
using OpcLabs.EasyOpc.UA.AddressSpace.Standard;
using OpcLabs.EasyOpc.UA.OperationModel;

namespace UADocExamples.AlarmsAndConditions
{
    class PullEventNotification
    {
        public static void Main1()
        {
            // Define which server we will work with.
            UAEndpointDescriptor endpointDescriptor =
                "opc.tcp://opcua.demo-this.com:62544/Quickstarts/AlarmConditionServer";

            // Instantiate the client object.
            // In order to use event pull, you must set a non-zero queue capacity upfront.
            var client = new EasyUAClient { PullEventNotificationQueueCapacity = 1000 };

            Console.WriteLine("Subscribing...");
            client.SubscribeEvent(endpointDescriptor, UAObjectIds.Server, 1000);

            Console.WriteLine("Processing event notifications for 30 seconds...");
            int endTick = Environment.TickCount + 30 * 1000;
            do
            {
                EasyUAEventNotificationEventArgs eventArgs = client.PullEventNotification(2 * 1000);
                if (!(eventArgs is null))
                    // Handle the notification event.
                    Console.WriteLine(eventArgs);
            } while (Environment.TickCount < endTick);

            Console.WriteLine("Unsubscribing...");
            client.UnsubscribeAllMonitoredItems();

            Console.WriteLine("Finished.");
        }

        // Example output (truncated):
        //Subscribing...
        //Processing event notifications for 30 seconds...
        //[] Success
        //[] Success; Refresh; RefreshInitiated
        //[] Success; Refresh; (10 field results) [EastTank] 100! "The dialog was activated" @9/10/2019 8:08:23 PM
        //[] Success; Refresh; (10 field results) [EastTank] 500! "The alarm was acknoweledged." @10/14/2019 4:00:13 PM
        //[] Success; Refresh; (10 field results) [EastTank] 100! "The alarm was acknoweledged." @11/9/2019 9:56:23 AM
        //[] Success; Refresh; (10 field results) [EastTank] 500! "The alarm was acknoweledged." @10/14/2019 4:00:17 PM
        //[] Success; Refresh; (10 field results) [EastTank] 100! "The alarm severity has increased." @9/10/2019 8:09:07 PM
        //[] Success; Refresh; (10 field results) [EastTank] 100! "The alarm severity has increased." @9/10/2019 8:10:09 PM
        //[] Success; Refresh; (10 field results) [NorthMotor] 100! "The dialog was activated" @9/10/2019 8:08:25 PM
        //[] Success; Refresh; (10 field results) [NorthMotor] 500! "The alarm was acknoweledged." @10/14/2019 4:00:02 PM
        //[] Success; Refresh; (10 field results) [NorthMotor] 500! "The alarm was acknoweledged." @10/14/2019 4:00:16 PM
        //[] Success; Refresh; (10 field results) [NorthMotor] 300! "The alarm severity has increased." @11/9/2019 10:29:42 AM
        //[] Success; Refresh; (10 field results) [NorthMotor] 100! "The alarm severity has increased." @9/10/2019 8:09:11 PM
        //[] Success; Refresh; (10 field results) [NorthMotor] 100! "The alarm severity has increased." @9/10/2019 8:10:19 PM
        //[] Success; Refresh; (10 field results) [WestTank] 100! "The dialog was activated" @9/10/2019 8:08:25 PM
        //[] Success; Refresh; (10 field results) [WestTank] 300! "The alarm was acknoweledged." @10/14/2019 4:00:12 PM
        //[] Success; Refresh; (10 field results) [WestTank] 300! "The alarm severity has increased." @11/9/2019 10:29:42 AM
        //[] Success; Refresh; (10 field results) [WestTank] 300! "The alarm was acknoweledged." @10/14/2019 4:00:04 PM
        //[] Success; Refresh; (10 field results) [WestTank] 100! "The alarm severity has increased." @9/10/2019 8:08:58 PM
        //[] Success; Refresh; (10 field results) [WestTank] 100! "The alarm severity has increased." @9/10/2019 8:09:48 PM
        //[] Success; Refresh; (10 field results) [SouthMotor] 100! "The dialog was activated" @9/10/2019 8:08:25 PM
        //[] Success; Refresh; (10 field results) [SouthMotor] 300! "The alarm severity has increased." @11/9/2019 10:29:42 AM
        //[] Success; Refresh; (10 field results) [SouthMotor] 700! "The alarm was acknoweledged." @10/14/2019 4:00:21 PM
        //[] Success; Refresh; (10 field results) [SouthMotor] 500! "The alarm was acknoweledged." @10/14/2019 4:00:03 PM
        //[] Success; Refresh; (10 field results) [SouthMotor] 100! "The alarm severity has increased." @9/10/2019 8:09:02 PM
        //[] Success; Refresh; (10 field results) [SouthMotor] 100! "The alarm severity has increased." @9/10/2019 8:09:59 PM
        //[] Success; Refresh; RefreshComplete
        //[] Success; (10 field results) [Internal] 500! "Raising Events" @11/9/2019 10:29:43 AM
        //[] Success; (10 field results) [Internal] 500! "Events Raised" @11/9/2019 10:29:43 AM
        //[] Success; (10 field results) [Internal] 500! "Raising Events" @11/9/2019 10:29:44 AM
        //[] Success; (10 field results) [Internal] 500! "Events Raised" @11/9/2019 10:29:44 AM
        //[] Success; (10 field results) [Internal] 500! "Raising Events" @11/9/2019 10:29:45 AM
        //[] Success; (10 field results) [Internal] 500! "Events Raised" @11/9/2019 10:29:45 AM
        //[] Success; (10 field results) [Internal] 500! "Raising Events" @11/9/2019 10:29:46 AM
        //[] Success; (10 field results) [Internal] 500! "Events Raised" @11/9/2019 10:29:46 AM
        //[] Success; (10 field results) [Internal] 500! "Raising Events" @11/9/2019 10:29:47 AM
        //[] Success; (10 field results) [Internal] 500! "Events Raised" @11/9/2019 10:29:47 AM
        //[] Success; (10 field results) [Internal] 500! "Raising Events" @11/9/2019 10:29:48 AM
        //[] Success; (10 field results) [Internal] 500! "Events Raised" @11/9/2019 10:29:48 AM
        //[] Success; (10 field results) [Internal] 500! "Raising Events" @11/9/2019 10:29:49 AM
        //[] Success; (10 field results) [Internal] 500! "Events Raised" @11/9/2019 10:29:49 AM
        //[] Success; (10 field results) [Internal] 500! "Raising Events" @11/9/2019 10:29:50 AM
        //[] Success; (10 field results) [Internal] 500! "Events Raised" @11/9/2019 10:29:50 AM
        //[] Success; (10 field results) [Internal] 500! "Raising Events" @11/9/2019 10:29:51 AM
        //[] Success; (10 field results) [Internal] 500! "Events Raised" @11/9/2019 10:29:51 AM
        //[] Success; (10 field results) [Internal] 500! "Raising Events" @11/9/2019 10:29:52 AM
        //[] Success; (10 field results) [Internal] 500! "Events Raised" @11/9/2019 10:29:52 AM
        //[] Success; (10 field results) [Internal] 500! "Raising Events" @11/9/2019 10:29:53 AM
        //[] Success; (10 field results) [NorthMotor] 500! "The alarm severity has increased." @11/9/2019 10:29:53 AM
        //[] Success; (10 field results) [Internal] 500! "Events Raised" @11/9/2019 10:29:53 AM
        //[] Success; (10 field results) [WestTank] 500! "The alarm severity has increased." @11/9/2019 10:29:53 AM
        //[] Success; (10 field results) [SouthMotor] 500! "The alarm severity has increased." @11/9/2019 10:29:53 AM
        //[] Success; (10 field results) [Internal] 500! "Raising Events" @11/9/2019 10:29:54 AM
        //[] Success; (10 field results) [Internal] 500! "Events Raised" @11/9/2019 10:29:54 AM
        //[] Success; (10 field results) [Internal] 500! "Raising Events" @11/9/2019 10:29:55 AM
        //...
    }
}
// This example shows how to subscribe to event notifications, pull events, and display each incoming event.
//
// Find all latest examples here : https://opclabs.doc-that.com/files/onlinedocs/OPCLabs-OpcStudio/Latest/examples.html .

class procedure PullEventNotification.Main;
var
  Client: EasyUAClient;
  EndTick: Cardinal;
  EventArgs: _EasyUAEventNotificationEventArgs;
begin
  // Instantiate the client object and hook events
  Client := CoEasyUAClient.Create;
  // In order to use event pull, you must set a non-zero queue capacity upfront.
  Client.PullEventNotificationQueueCapacity := 1000;

  WriteLn('Subscribing...');
  Client.SubscribeEvent(
    'opc.tcp://opcua.demo-this.com:62544/Quickstarts/AlarmConditionServer',
    'nsu=http://opcfoundation.org/UA/;i=2253',  // UAObjectIds.Server
    1000);

  WriteLn('Processing event notifications for 30 seconds...');
  EndTick := GetTickCount + 60*1000;
  while GetTickCount < EndTick do
  begin
    EventArgs := Client.PullEventNotification(2*1000);
    if EventArgs <> nil then
      // Handle the notification event
      WriteLn(EventArgs.ToString);
  end;

  WriteLn('Unsubscribing...');
  Client.UnsubscribeAllMonitoredItems;

  WriteLn('Finished.');
end;
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