QuickOPC User's Guide and Reference
PullNotification Method (IEasyAEClientExtension)
Example 



OpcLabs.EasyOpcClassic Assembly > OpcLabs.EasyOpc.AlarmsAndEvents Namespace > IEasyAEClientExtension Class : PullNotification Method
The client object that will perform the operation.
The number of milliseconds to wait, or System.Threading.Timeout.Infinite (-1) to wait indefinitely.
Attempts to pull an OPC event subscribed to by the SubscribeEvents method. Returns refresh or standard event notifications.
Syntax
'Declaration
 
<ExtensionAttribute()>
<CanBeNullAttribute()>
Public Shared Function PullNotification( _
   ByVal client As IEasyAEClient, _
   ByVal millisecondsTimeout As Integer _
) As EasyAENotificationEventArgs
'Usage
 
Dim client As IEasyAEClient
Dim millisecondsTimeout As Integer
Dim value As EasyAENotificationEventArgs
 
value = IEasyAEClientExtension.PullNotification(client, millisecondsTimeout)
[Extension()]
[CanBeNull()]
public static EasyAENotificationEventArgs PullNotification( 
   IEasyAEClient client,
   int millisecondsTimeout
)
[Extension()]
[CanBeNull()]
public:
static EasyAENotificationEventArgs^ PullNotification( 
   IEasyAEClient^ client,
   int millisecondsTimeout
) 

Parameters

client
The client object that will perform the operation.
millisecondsTimeout
The number of milliseconds to wait, or System.Threading.Timeout.Infinite (-1) to wait indefinitely.

Return Value

The event arguments, or null if no event is available within the specified time.
Exceptions
ExceptionDescription
A null reference (Nothing in Visual Basic) is passed to a method that does not accept it as a valid argument.
The value of an argument is outside the allowable range of values as defined by the invoked method.
Example
// This example shows how to subscribe to events and obtain the notification events by pulling them.

using System;
using OpcLabs.EasyOpc.AlarmsAndEvents;
using OpcLabs.EasyOpc.AlarmsAndEvents.OperationModel;

namespace DocExamples.AlarmsAndEvents._EasyAEClient
{
    class PullNotification
    {
        public static void Main1()
        {
            // Instantiate the client object.
            // In order to use event pull, you must set a non-zero queue capacity upfront.
            using (var client = new EasyAEClient { PullNotificationQueueCapacity = 1000 })
            {
                Console.WriteLine("Subscribing events...");
                int handle = client.SubscribeEvents("", "OPCLabs.KitEventServer.2", 1000);

                Console.WriteLine("Processing event notifications for 1 minute...");
                int endTick = Environment.TickCount + 60 * 1000;
                do
                {
                    EasyAENotificationEventArgs eventArgs = client.PullNotification(2 * 1000);
                    if (!(eventArgs is null))
                        // Handle the notification event
                        Console.WriteLine(eventArgs);
                } while (Environment.TickCount < endTick);

                Console.WriteLine("Unsubscribing events...");
                client.UnsubscribeEvents(handle);

                Console.WriteLine("Finished.");
            }
        }
    }
}
# This example shows how to subscribe to events and obtain the notification events by pulling them.

#requires -Version 5.1
using namespace OpcLabs.EasyOpc.AlarmsAndEvents

# The path below assumes that the current directory is [ProductDir]/Examples-NET/PowerShell/Windows .
Add-Type -Path "../../../Assemblies/net47/OpcLabs.EasyOpcClassic.dll"

# Instantiate the client object.
$client = New-Object EasyAEClient
# In order to use event pull, you must set a non-zero queue capacity upfront.
$client.PullNotificationQueueCapacity = 1000

Write-Host "Subscribing events..."
$handle = [OpcLabs.EasyOpc.AlarmsAndEvents.IEasyAEClientExtension]::SubscribeEvents($client, 
    "", "OPCLabs.KitEventServer.2", 1000)

Write-Host "Processing event notifications for 1 minute..."
$stopwatch =  [System.Diagnostics.Stopwatch]::StartNew() 
while ($stopwatch.Elapsed.TotalSeconds -lt 60) {    
    $eventArgs = $client.PullNotification(2*1000)
    if ($eventArgs -ne $null) {
        # Handle the notification event
        Write-Host $eventArgs
    }
}

Write-Host "Unsubscribing events..."
$client.UnsubscribeEvents($handle)

Write-Host "Finished."
// This example shows how to subscribe to events and obtain the notification events by pulling them.

$ServerDescriptor = new COM("OpcLabs.EasyOpc.ServerDescriptor");
$ServerDescriptor->ServerClass = "OPCLabs.KitEventServer.2";

$Client = new COM("OpcLabs.EasyOpc.AlarmsAndEvents.EasyAEClient");
// In order to use event pull, you must set a non-zero queue capacity upfront.
$Client->PullNotificationQueueCapacity = 1000;

print "Subscribing events...\n";
$SubscriptionParameters = new COM("OpcLabs.EasyOpc.AlarmsAndEvents.AESubscriptionParameters");
$SubscriptionParameters->NotificationRate = 1000;
$handle = $Client->SubscribeEvents($ServerDescriptor, $SubscriptionParameters, TRUE, NULL);

print "Processing event notifications for 1 minute...\n";
$endTime = time() + 60;
do {
    $EventArgs = $Client->PullNotification(2*1000);
    if (!is_null($EventArgs)) {
        // Handle the notification event
        print $EventArgs->ToString();
        print "\n";
    }
} while (time() < $endTime);

print "Unsubscribing events...\n";
$Client->UnsubscribeEvents($handle);

print "Finished.\n";
Rem This example shows how to subscribe to events and obtain the notification events by pulling them.

Private Sub PullNotification_Main_Command_Click()
    OutputText = ""
    
    Dim eventArgs As EasyAENotificationEventArgs
    
    Dim serverDescriptor As New serverDescriptor
    serverDescriptor.ServerClass = "OPCLabs.KitEventServer.2"
        
    ' Instantiate the client object
    Dim client As New EasyAEClient
    
    ' In order to use event pull, you must set a non-zero queue capacity upfront.
    client.PullNotificationQueueCapacity = 1000
    
    OutputText = OutputText & "Subscribing events..." & vbCrLf
    Dim subscriptionParameters As New AESubscriptionParameters
    subscriptionParameters.notificationRate = 1000
    Dim handle
    Dim state
    handle = client.SubscribeEvents(serverDescriptor, subscriptionParameters, True, state)

    OutputText = OutputText & "Processing event notifications for 1 minute..." & vbCrLf
    Dim endTick As Long
    endTick = GetTickCount + 60000
    While GetTickCount < endTick
        Set eventArgs = client.PullNotification(2 * 1000)
        If Not eventArgs Is Nothing Then
            ' Handle the notification event
            OutputText = OutputText & eventArgs & vbCrLf
        End If
    Wend
    
    OutputText = OutputText & "Unsubscribing events..." & vbCrLf
    client.UnsubscribeEvents handle

    OutputText = OutputText & "Finished." & vbCrLf

End Sub
' This example shows how to subscribe to events and obtain the notification events by pulling them.

Imports OpcLabs.EasyOpc.AlarmsAndEvents
Imports OpcLabs.EasyOpc.AlarmsAndEvents.OperationModel

Namespace DocExamples.AlarmsAndEvents._EasyAEClient
    Partial Friend Class PullNotification
        Public Shared Sub Main1()
            Using client = New EasyAEClient()
                ' In order to use event pull, you must set a non-zero queue capacity upfront.
                client.PullNotificationQueueCapacity = 1000

                Console.WriteLine("Subscribing events...")
                Dim handle As Integer = client.SubscribeEvents("", "OPCLabs.KitEventServer.2", 1000)

                Console.WriteLine("Processing event notifications for 1 minute...")
                Dim endTick As Integer = Environment.TickCount + 60 * 1000
                Do
                    Dim eventArgs As EasyAENotificationEventArgs = client.PullNotification(2 * 1000)
                    If Not eventArgs Is Nothing Then
                        ' Handle the notification event
                        Console.WriteLine(eventArgs)
                    End If
                Loop While Environment.TickCount < endTick

                Console.WriteLine("Unsubscribing events...")
                client.UnsubscribeEvents(handle)
            End Using

            Console.WriteLine("Finished.")
        End Sub
    End Class
End Namespace
Requirements

Target Platforms: .NET Framework: Windows 10, Windows Server 2012, Windows Server 2016; .NET Core, .NET 5: Linux, macOS, Microsoft Windows

See Also

Reference

IEasyAEClientExtension Class
IEasyAEClientExtension Members