Examples - OPC UA Alarms&Conditions - Callback using lambda or regular method

.NET

C#
VB.NET

// This example shows how to subscribe to event notifications and display each incoming event
// using a callback method that is provided as lambda expression.
//
// Find all latest examples here: https://opclabs.doc-that.com/files/onlinedocs/OPCLabs-OpcStudio/Latest/examples.html .
// OPC client and subscriber examples in C# on GitHub: https://github.com/OPCLabs/Examples-QuickOPC-CSharp .
// Missing some example? Ask us for it on our Online Forums, https://www.opclabs.com/forum/index ! You do not have to own
// a commercial license in order to use Online Forums, and we reply to every post.

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

namespace UADocExamples.AlarmsAndConditions
{
    partial class SubscribeEvent
    {
        public static void CallbackLambda()
        {
            UAEndpointDescriptor endpointDescriptor =
                "opc.tcp://opcua.demo-this.com:62544/Quickstarts/AlarmConditionServer";

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

            Console.WriteLine("Subscribing...");
            // The callback is a lambda expression the displays the event
            client.SubscribeEvent(
                endpointDescriptor,
                UAObjectIds.Server,
                1000,
                (sender, eventArgs) => Console.WriteLine(eventArgs));
            // Remark: Production code needs to check eventArgs.Exception before accessing eventArgs.EventData.

            Console.WriteLine("Processing event notifications for 30 seconds...");
            System.Threading.Thread.Sleep(30 * 1000);

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

            Console.WriteLine("Waiting for 2 seconds...");
            System.Threading.Thread.Sleep(2 * 1000);
        }
    }
}

' This example shows how to subscribe to event notifications and display each incoming event
' using a callback method that is provided as lambda expression.
'
' Find all latest examples here: https://opclabs.doc-that.com/files/onlinedocs/OPCLabs-OpcStudio/Latest/examples.html .
' OPC client and subscriber examples in VB.NET on GitHub: https://github.com/OPCLabs/Examples-QuickOPC-VBNET .
' Missing some example? Ask us for it on our Online Forums, https://www.opclabs.com/forum/index ! You do not have to own
' a commercial license in order to use Online Forums, and we reply to every post.

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

Namespace AlarmsAndConditions
    Partial Friend Class SubscribeEvent
        Public Shared Sub CallbackLambda()
            ' Instantiate the client object
            Dim client = New EasyUAClient()

            Console.WriteLine("Subscribing...")
            ' The callback is a lambda expression the displays the event
            client.SubscribeEvent( _
                "opc.tcp://opcua.demo-this.com:62544/Quickstarts/AlarmConditionServer", _
                UAObjectIds.Server, _
                1000, _
                Sub(sender, eventArgs) Console.WriteLine(eventArgs))
            ' Remark: Production code would check e.Exception before accessing e.EventData.

            Console.WriteLine("Processing event notifications for 10 seconds...")
            Threading.Thread.Sleep(10 * 1000)

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

            Console.WriteLine("Waiting for 2 seconds...")
            Threading.Thread.Sleep(2 * 1000)
        End Sub
    End Class
End Namespace

Python

Python (.NET)

# This example shows how to subscribe to event notifications and display each incoming event
# using a callback method that is provided as lambda expression.
#
# 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 .
# Missing some example? Ask us for it on our Online Forums, https://www.opclabs.com/forum/index ! You do not have to own
# a commercial license in order to use Online Forums, and we reply to every post.
# The QuickOPC package is needed. Install it using "pip install opclabs_quickopc".
import opclabs_quickopc
import time

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


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

# Instantiate the client object.
client = EasyUAClient()

print('Subscribing...')
# The callback is a lambda expression the displays the event.
IEasyUAClientExtension.SubscribeEvent(
    client,
    endpointDescriptor,
    UANodeDescriptor(UAObjectIds.Server),
    1000,
    EasyUAEventNotificationEventHandler(lambda server, eventArgs: print(eventArgs)))
# Remark: Production code needs to check eventArgs.Exception before accessing eventArgs.EventData.

print('Processing event notifications for 30 seconds...')
time.sleep(30)

print('Unsubscribing...')
client.UnsubscribeAllMonitoredItems()

print('Waiting for 2 seconds...')
time.sleep(2)

print('Finished.')

.NET

Python

Concepts

Examples - Client OPC Alarms&Events

Examples - Client OPC Unified Architecture