QuickOPC User's Guide and Reference
Sources Property (AESubscriptionFilter)
Example 



OpcLabs.EasyOpcClassic Assembly > OpcLabs.EasyOpc.AlarmsAndEvents Namespace > AESubscriptionFilter Class : Sources Property
Array of event sources of interest - only events from these sources will be reported.
Syntax
'Declaration
 
<DataMemberAttribute()>
<ElementsNotNullAttribute()>
<NotNullAttribute()>
Public Property Sources As AENodeDescriptor()
'Usage
 
Dim instance As AESubscriptionFilter
Dim value() As AENodeDescriptor
 
instance.Sources = value
 
value = instance.Sources
[DataMember()]
[ElementsNotNull()]
[NotNull()]
public AENodeDescriptor[] Sources {get; set;}
[DataMember()]
[ElementsNotNull()]
[NotNull()]
public:
property array<AENodeDescriptor^>^ Sources {
   array<AENodeDescriptor^>^ get();
   void set (    array<AENodeDescriptor^>^ value);
}
Remarks
Source strings can be obtained using browsing. It is possible to specify sources using the wildcard syntax.
Example
// This example shows how to set the filtering criteria to be used for the event subscription.

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

namespace DocExamples.AlarmsAndEvents._AESubscriptionFilter
{
    class Properties
    {
        // Instantiate the OPC-A&E client object.
        static readonly EasyAEClient AEClient = new EasyAEClient();


        // Instantiate the OPC-DA client object.
        static readonly EasyDAClient DAClient = new EasyDAClient();

        public static void Main1()
        {
            var eventHandler = new EasyAENotificationEventHandler(aeClient_Notification);
            AEClient.Notification += eventHandler;

            Console.WriteLine("Processing event notifications...");
            var subscriptionFilter = new AESubscriptionFilter
            {
                Sources = new AENodeDescriptor[] { "Simulation.ConditionState1", "Simulation.ConditionState3" }
            };
            // You can also filter using event types, categories, severity, and areas.
            int handle = AEClient.SubscribeEvents("", "OPCLabs.KitEventServer.2", 1000, null, subscriptionFilter);

            // Allow time for initial refresh
            Thread.Sleep(5 * 1000);

            // Set some events to active state.
            try
            {
                // The activation below will come from a source contained in a filter and the notification will arrive.
                DAClient.WriteItemValue("", "OPCLabs.KitServer.2", "SimulateEvents.ConditionState1.Activate", true);
                // The activation below will come from a source that is not contained in a filter and the notification will not arrive.
                DAClient.WriteItemValue("", "OPCLabs.KitServer.2", "SimulateEvents.ConditionState2.Activate", true);
            }
            catch (OpcException opcException)
            {
                Console.WriteLine("*** Failure: {0}", opcException.GetBaseException().Message);
                return;
            }

            Thread.Sleep(10 * 1000);

            AEClient.UnsubscribeEvents(handle);
            AEClient.Notification -= eventHandler;
        }

        // Notification event handler
        static void aeClient_Notification(object sender, EasyAENotificationEventArgs e)
        {
            Console.WriteLine();
            if (!e.Succeeded)
            {
                Console.WriteLine("*** Failure: {0}", e.ErrorMessageBrief);
                return;
            }

            Console.WriteLine("Refresh: {0}", e.Refresh);
            Console.WriteLine("RefreshComplete: {0}", e.RefreshComplete);
            AEEventData eventData = e.EventData;
            if (!(eventData is null))
            {
                Console.WriteLine("Event.QualifiedSourceName: {0}", eventData.QualifiedSourceName);
                Console.WriteLine("Event.Message: {0}", eventData.Message);
                Console.WriteLine("Event.Active: {0}", eventData.Active);
                Console.WriteLine("Event.Acknowledged: {0}", eventData.Acknowledged);
            }
        }
    }
}
' This example shows how to set the filtering criteria to be used for the event subscription.

Imports System.Threading
Imports OpcLabs.EasyOpc.AlarmsAndEvents
Imports OpcLabs.EasyOpc.AlarmsAndEvents.OperationModel
Imports OpcLabs.EasyOpc.DataAccess
Imports OpcLabs.EasyOpc.OperationModel

Namespace DocExamples.AlarmsAndEvents._AESubscriptionFilter

    Friend Class Properties
        _
        Private Shared ReadOnly AEClient As New EasyAEClient()
        _
        Private Shared ReadOnly DAClient As New EasyDAClient()

        Public Shared Sub Main1()
            Dim eventHandler = New EasyAENotificationEventHandler(AddressOf AEClient_Notification)
            AddHandler AEClient.Notification, eventHandler

            Console.WriteLine("Processing event notifications...")
            Dim subscriptionFilter As New AESubscriptionFilter
            subscriptionFilter.Sources = New AENodeDescriptor() {"Simulation.ConditionState1", "Simulation.ConditionState3"}
            ' You can also filter using event types, categories, severity, and areas.
            Dim handle As Integer = AEClient.SubscribeEvents("", "OPCLabs.KitEventServer.2", 1000, Nothing, subscriptionFilter)

            ' Allow time for initial refresh
            Thread.Sleep(5 * 1000)

            ' Set some events to active state.
            Try
                ' The activation below will come from a source contained in a filter and the notification will arrive.
                DAClient.WriteItemValue("", "OPCLabs.KitServer.2", "SimulateEvents.ConditionState1.Activate", True)
                ' The activation below will come from a source that is not contained in a filter and the notification will not arrive.
                DAClient.WriteItemValue("", "OPCLabs.KitServer.2", "SimulateEvents.ConditionState2.Activate", True)
            Catch opcException As OpcException
                Console.WriteLine("*** Failure: {0}", opcException.GetBaseException().Message)
                Exit Sub
            End Try

            Thread.Sleep(10 * 1000)

            AEClient.UnsubscribeEvents(handle)
            RemoveHandler AEClient.Notification, eventHandler
        End Sub

        ' Notification event handler
        Private Shared Sub AEClient_Notification(ByVal sender As Object, ByVal e As EasyAENotificationEventArgs)
            Console.WriteLine()
            If Not e.Succeeded Then
                Console.WriteLine("*** Failure: {0}", e.ErrorMessageBrief)
                Exit Sub
            End If

            Console.WriteLine("Refresh: {0}", e.Refresh)
            Console.WriteLine("RefreshComplete: {0}", e.RefreshComplete)
            If e.EventData IsNot Nothing Then
                Dim eventData As AEEventData = e.EventData
                Console.WriteLine("EventData.QualifiedSourceName: {0}", eventData.QualifiedSourceName)
                Console.WriteLine("EventData.Message: {0}", eventData.Message)
                Console.WriteLine("EventData.Active: {0}", eventData.Active)
                Console.WriteLine("EventData.Acknowledged: {0}", eventData.Acknowledged)
            End If
        End Sub
    End Class
End Namespace
Requirements

Target Platforms: .NET Framework: Windows 10 (selected versions), Windows 11 (selected versions), Windows Server 2012, Windows Server 2016; .NET Core, .NET 5, .NET 6: Linux, macOS, Microsoft Windows

See Also

Reference

AESubscriptionFilter Class
AESubscriptionFilter Members