Browsing for OPC UA Event Sources

In order to browse for event sources, you can use the pre-made browse parameters available in the UABrowseParameters.EventSources static property, and call the IEasyUAClient.Browse Method with them. Alternatively, you can use a dedicated extension method, IEasyUAClient.BrowseEventSources, to perform browsing for event sources easily.

.NET

// This example shows how to browse objects under the "Objects" node and display event sources.
//
// 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;
using OpcLabs.EasyOpc.UA.AddressSpace.Standard;
using OpcLabs.EasyOpc.UA.OperationModel;

namespace UADocExamples.AlarmsAndConditions
{
    class BrowseEventSources
    {
        public static void Overload2()
        {
            // Start browsing from the "Objects" node.
            try
            {
                BrowseFrom(UAObjectIds.ObjectsFolder);
            }
            catch (UAException uaException)
            {
                Console.WriteLine($"*** Failure: {uaException.GetBaseException().Message}");
            }

            Console.WriteLine();
            Console.WriteLine("Finished.");
        }

        private static void BrowseFrom(UANodeDescriptor nodeDescriptor)
        {
            // Define which server we will work with.
            UAEndpointDescriptor endpointDescriptor =
                "opc.tcp://opcua.demo-this.com:62544/Quickstarts/AlarmConditionServer";

            Console.WriteLine();
            Console.WriteLine();
            Console.WriteLine($"Parent node: {nodeDescriptor}");

            // Instantiate the client object.
            var client = new EasyUAClient();

            // Obtain event sources.
            UANodeElementCollection eventSourceNodeElementCollection = client.BrowseEventSources(
                endpointDescriptor, nodeDescriptor);

            // Display event sources.
            if (eventSourceNodeElementCollection.Count != 0)
            {
                Console.WriteLine();
                Console.WriteLine("Event sources:");
                foreach (UANodeElement eventSourceNodeElement in eventSourceNodeElementCollection)
                    Console.WriteLine(eventSourceNodeElement);
            }

            // Obtain objects.
            UANodeElementCollection objectNodeElementCollection = client.BrowseObjects(
                endpointDescriptor, nodeDescriptor);

            // Recurse.
            foreach (UANodeElement objectNodeElement in objectNodeElementCollection)
                BrowseFrom(objectNodeElement);
        }


        // Example output (truncated):
        //
        //
        //Parent node: ObjectsFolder
        //
        //
        //Parent node: Server
        //
        //Event sources:
        //Green -> nsu=http://opcfoundation.org/Quickstarts/AlarmCondition ;ns=2;s=0:/Green (Object)
        //Yellow -> nsu=http://opcfoundation.org/Quickstarts/AlarmCondition ;ns=2;s=0:/Yellow (Object)
        //
        //
        //Parent node: Server_ServerCapabilities
        //...
    }
}

# This example shows how to browse objects under the "Objects" node and display event sources.
#
# Find all latest examples here: https://opclabs.doc-that.com/files/onlinedocs/OPCLabs-OpcStudio/Latest/examples.html .

#requires -Version 5.1
using namespace OpcLabs.EasyOpc.UA
using namespace OpcLabs.EasyOpc.UA.AddressSpace.Standard
using namespace OpcLabs.EasyOpc.UA.Navigation.Parsing;
using namespace OpcLabs.EasyOpc.UA.OperationModel


function BrowseEventSourcesFrom([UANodeDescriptor]$nodeDescriptor) { 

    # Define which server we will work with.
    [UAEndpointDescriptor]$endpointDescriptor = "opc.tcp://opcua.demo-this.com:62544/Quickstarts/AlarmConditionServer"

    Write-Host
    Write-Host
    Write-Host "Parent node: $($nodeDescriptor)"

    # Instantiate the client object.
    $client = New-Object EasyUAClient

    # Obtain event sources.
    $eventSourceNodeElementCollection = [IEasyUAClientExtension]::BrowseEventSources($client,
        $endpointDescriptor, $nodeDescriptor)

    # Display event sources.
    if ($eventSourceNodeElementCollection.Count -ne 0) {
        Write-Host
        Write-Host "Event sources:"
        foreach ($eventSourceNodeElement in $eventSourceNodeElementCollection) {
            Write-Host $eventSourceNodeElement
        }
    }

    # Obtain objects.
    $objectNodeElementCollection = [IEasyUAClientExtension]::BrowseObjects($client,
        $endpointDescriptor, $nodeDescriptor)

    # Recurse.
    foreach ($objectNodeElement in $objectNodeElementCollection) {
        BrowseEventSourcesFrom($objectNodeElement)
    }
}


# The path below assumes that the current directory is [ProductDir]/Examples-NET/PowerShell/Windows .
Add-Type -Path "../../../Components/Opclabs.QuickOpc/net472/OpcLabs.EasyOpcUA.dll"
Add-Type -Path "../../../Components/Opclabs.QuickOpc/net472/OpcLabs.EasyOpcUAComponents.dll"

# Start browsing from the "Objects" node.
try {
    [UANodeDescriptor]$startingNodeDescriptor = [UAObjectIds]::ObjectsFolder
    BrowseEventSourcesFrom $startingNodeDescriptor
}
catch [UAException] {
    Write-Host "*** Failure: $($PSItem.Exception.GetBaseException().Message)"
    return
}

Write-Host
Write-Host "Finished."


# Example output (truncated):
#
#
#Parent node: ObjectsFolder
#
#
#Parent node: Server
#
#Event sources:
#Green -> nsu=http:#opcfoundation.org/Quickstarts/AlarmCondition ;ns=2;s=0:/Green (Object)
#Yellow -> nsu=http:#opcfoundation.org/Quickstarts/AlarmCondition ;ns=2;s=0:/Yellow (Object)
#
#
#Parent node: Server_ServerCapabilities
#...

# This example shows how to browse objects under the "Objects" node and display event sources.
#
# Find all latest examples here: https://opclabs.doc-that.com/files/onlinedocs/OPCLabs-OpcStudio/Latest/examples.html .
# OPC client and subscriber examples in Python on GitHub: https://github.com/OPCLabs/Examples-QuickOPC-Python .
# The QuickOPC package is needed. Install it using "pip install opclabs_quickopc".
import opclabs_quickopc

# Import .NET namespaces.
from OpcLabs.EasyOpc.UA import *
from OpcLabs.EasyOpc.UA.AddressSpace import *
from OpcLabs.EasyOpc.UA.AddressSpace.Standard import *
from OpcLabs.EasyOpc.UA.OperationModel import *


# Define which server we will work with.
endpointDescriptor = UAEndpointDescriptor('opc.tcp://opcua.demo-this.com:62544/Quickstarts/AlarmConditionServer')


def browseFrom(nodeDescriptor):
    global endpointDescriptor

    print()
    print()
    print('Parent node: ', nodeDescriptor, sep='')

    # Instantiate the client object.
    client = EasyUAClient()

    # Obtain event sources.
    eventSourceNodeElementCollection = IEasyUAClientExtension.BrowseEventSources(client,
                                                                                 endpointDescriptor,
                                                                                 nodeDescriptor)

    # Display event sources.
    if eventSourceNodeElementCollection.Count != 0:
        print('')
        print('Event sources:')
        for eventSourceNodeElement in eventSourceNodeElementCollection:
            print(eventSourceNodeElement)

    # Obtain objects.
    objectNodeElementCollection = IEasyUAClientExtension.BrowseObjects(client,
                                                                       endpointDescriptor,
                                                                       nodeDescriptor)

    # Recurse.
    for objectNodeElement in objectNodeElementCollection:
        browseFrom(objectNodeElement.ToUANodeDescriptor())


# Start browsing from the "Objects" node.
try:
    browseFrom(UANodeDescriptor(UAObjectIds.ObjectsFolder))
except UAException as uaException:
    print('*** Failure: ' + uaException.GetBaseException().Message)
    exit()

print()
print('Finished.')

' This example shows how to browse objects under the "Objects" node and display event sources.
'
' Find all latest examples here: https://opclabs.doc-that.com/files/onlinedocs/OPCLabs-OpcStudio/Latest/examples.html .

Imports OpcLabs.EasyOpc.UA
Imports OpcLabs.EasyOpc.UA.AddressSpace
Imports OpcLabs.EasyOpc.UA.AddressSpace.Standard
Imports OpcLabs.EasyOpc.UA.OperationModel

Namespace AlarmsAndConditions
    Friend Class BrowseEventSources
        Public Shared Sub Overload2()

            ' Start browsing from the "Objects" node
            Try
                BrowseFrom(UAObjectIds.ObjectsFolder)
            Catch uaException As UAException
                Console.WriteLine("*** Failure: {0}", uaException.GetBaseException.Message)
            End Try
        End Sub

        Private Shared Sub BrowseFrom(nodeDescriptor As UANodeDescriptor)

            Console.WriteLine()
            Console.WriteLine()
            Console.WriteLine("Parent node: {0}", nodeDescriptor)

            ' Instantiate the client object
            Dim client = New EasyUAClient()

            ' Obtain notifiers
            Dim eventSourceNodeElementCollection As UANodeElementCollection = client.BrowseEventSources( _
                "opc.tcp://opcua.demo-this.com:62544/Quickstarts/AlarmConditionServer", _
                nodeDescriptor)

            ' Display notifiers
            Console.WriteLine()
            Console.WriteLine("Event sources:")
            For Each eventSourceNodeElement As UANodeElement In eventSourceNodeElementCollection
                Console.WriteLine(eventSourceNodeElement)
            Next eventSourceNodeElement

            ' Obtain objects
            Dim objectNodeElementCollection = client.BrowseObjects( _
                "opc.tcp://opcua.demo-this.com:62544/Quickstarts/AlarmConditionServer", _
                nodeDescriptor)

            ' Recurse
            For Each objectNodeElement As UANodeElement In objectNodeElementCollection
                BrowseFrom(objectNodeElement)
            Next objectNodeElement
        End Sub
    End Class
End Namespace

COM

// This example shows how to browse objects under the "Objects" node and display event sources.
//
// Find all latest examples here : https://opclabs.doc-that.com/files/onlinedocs/OPCLabs-OpcStudio/Latest/examples.html .

class procedure BrowseEventSources.Main;
var
  ObjectNodeId: _UANodeId;
begin
  ObjectNodeId := CoUANodeId.Create;
  ObjectNodeId.StandardName := 'Objects';
  try
    BrowseFrom(ObjectNodeId);
  except
    on E: EOleException do
    begin
      WriteLn(Format('*** Failure: %s', [E.GetBaseException.Message]));
      Exit;
    end;
  end;
end;

class procedure BrowseEventSources.BrowseFrom(NodeId: _UANodeId);
var
  Client: OpcLabs_EasyOpcUA_TLB._EasyUAClient;
  Count: Cardinal;
  Element: OleVariant;
  EndpointDescriptor: string;
  EventSourceNodeElement: _UANodeElement;
  EventSourceNodeElementEnumerator: IEnumVariant;
  EventSourceNodeElements: _UANodeElementCollection;
  ObjectNodeElement: _UANodeElement;
  ObjectNodeElementEnumerator: IEnumVariant;
  ObjectNodeElements: _UANodeElementCollection;
begin
  EndpointDescriptor := 'opc.tcp://opcua.demo-this.com:62544/Quickstarts/AlarmConditionServer';

  WriteLn;
  WriteLn;
  WriteLn('Parent node: ', NodeId.ToString);

  // Instantiate the client object
  Client := CoEasyUAClient.Create;

  // Obtain event sources
  EventSourceNodeElements := Client.BrowseEventSources(EndpointDescriptor, NodeId.ExpandedText);

  // Display event sources
  if EventSourceNodeElements.Count <> 0 then
  begin
    WriteLn;
    WriteLn('Event sources:');
    EventSourceNodeElementEnumerator := EventSourceNodeElements.GetEnumerator;
    while (EventSourceNodeElementEnumerator.Next(1, Element, Count) = S_OK) do
    begin
      EventSourceNodeElement := IUnknown(Element) as _UANodeElement;
      WriteLn(EventSourceNodeElement.ToString);
    end;
  end;

  // Obtain objects
  ObjectNodeElements := Client.BrowseObjects(EndpointDescriptor, NodeId.ExpandedText);

  // Recurse
  ObjectNodeElementEnumerator := ObjectNodeElements.GetEnumerator;
  while (ObjectNodeElementEnumerator.Next(1, Element, Count) = S_OK) do
  begin
    ObjectNodeElement := IUnknown(Element) as _UANodeElement;
    BrowseFrom(ObjectNodeElement.NodeId);
  end;
end;

// This example shows how to browse objects under the "Objects" node and display event sources.
//
// Find all latest examples here : https://opclabs.doc-that.com/files/onlinedocs/OPCLabs-OpcStudio/Latest/examples.html .


// Start browsing from the "Objects" node
$ObjectNodeId = new COM("OpcLabs.EasyOpc.UA.AddressSpace.UANodeId");
$ObjectNodeId->StandardName = "Objects";
try
{
    BrowseFrom($ObjectNodeId);
}
catch (com_exception $e)
{
    printf("*** Failure: %s\n", $e->getMessage());
    exit();
}

function BrowseFrom($NodeId) {
    $EndpointDescriptor = "opc.tcp://opcua.demo-this.com:62544/Quickstarts/AlarmConditionServer";

    printf("\n");
    printf("\n");
    printf("Parent node: %s\n", $NodeId);

    // Instantiate the client object
    $Client = new COM("OpcLabs.EasyOpc.UA.EasyUAClient");

    // Obtain event sources
    $EventSourceNodeElements = $Client->BrowseEventSources($EndpointDescriptor, $NodeId->ExpandedText);

    // Display event sources
    if ($EventSourceNodeElements->Count != 0) {
        printf("\n");
        printf("Event sources:\n");
        foreach ($EventSourceNodeElements as $EventSourceNodeElement)
        {
             printf("%s\n", $EventSourceNodeElement);
        }
     }

    // Obtain objects
    $ObjectNodeElements = $Client->BrowseObjects($EndpointDescriptor, $NodeId->ExpandedText);

    // Recurse
    foreach ($ObjectNodeElements as $ObjectNodeElement)
    {
         BrowseFrom($ObjectNodeElement->NodeId);
    }
}

// Example output (truncated):
//
//
//Parent node: ObjectsFolder
//
//
//Parent node: Server
//
//Event sources:
//Green -> nsu=http://opcfoundation.org/Quickstarts/AlarmCondition ;ns=2;s=0:/Green (Object)
//Yellow -> nsu=http://opcfoundation.org/Quickstarts/AlarmCondition ;ns=2;s=0:/Yellow (Object)
//
//
//Parent node: Server_ServerCapabilities
//...

Rem This example shows how to browse objects under the "Objects" node and display event sources.
Rem
Rem Find all latest examples here : https://opclabs.doc-that.com/files/onlinedocs/OPCLabs-OpcStudio/Latest/examples.html .

Option Explicit

' Start browsing from the "Objects" node
Dim ObjectsNodeId: Set ObjectsNodeId = CreateObject("OpcLabs.EasyOpc.UA.AddressSpace.UANodeId")
ObjectsNodeId.StandardName = "Objects"
On Error Resume Next
BrowseFrom ObjectsNodeId
If Err.Number <> 0 Then
    WScript.Echo "*** Failure: " & Err.Source & ": " & Err.Description
    WScript.Quit
End If
On Error Goto 0



Sub BrowseFrom(NodeId)
    Dim endpointDescriptor
    endpointDescriptor = "opc.tcp://opcua.demo-this.com:62544/Quickstarts/AlarmConditionServer"

    WScript.Echo 
    WScript.Echo 
    WScript.Echo "Parent node: " & NodeId

    ' Instantiate the client object
    Dim Client: Set Client = CreateObject("OpcLabs.EasyOpc.UA.EasyUAClient")

    ' Obtain event sources
    Dim EventSourceNodeElementCollection: Set EventSourceNodeElementCollection = Client.BrowseEventSources( _
        endpointDescriptor, NodeId.ExpandedText)

    ' Display event sources
    If EventSourceNodeElementCollection.Count <> 0 Then
        WScript.Echo 
        WScript.Echo "Event sources:"
        Dim EventSourceNodeElement: For Each EventSourceNodeElement In EventSourceNodeElementCollection
            WScript.Echo EventSourceNodeElement
        Next
    End If
    
    ' Obtain objects
    Dim ObjectNodeElementCollection: Set ObjectNodeElementCollection = Client.BrowseObjects( _
        endpointDescriptor, NodeId.ExpandedText)

    ' Recurse
    Dim ObjectNodeElement: For Each ObjectNodeElement In ObjectNodeElementCollection
        BrowseFrom ObjectNodeElement.NodeId
    Next
End Sub



' Example output (truncated):
'
'
'Parent node: ObjectsFolder
'
'
'Parent node: Server
'
'Event sources:
'Green -> nsu=http://opcfoundation.org/Quickstarts/AlarmCondition ;ns=2;s=0:/Green (Object)
'Yellow -> nsu=http://opcfoundation.org/Quickstarts/AlarmCondition ;ns=2;s=0:/Yellow (Object)
'
'
'Parent node: Server_ServerCapabilities
'...

Examples - OPC UA Alarms&Conditions

Examples - OPC UA Alarms&Conditions - Browsing for event sources