// This example shows how to implement own handling of data subscriptions.
// You can use any OPC UA client, including our Connectivity Explorer and OpcCmd utility, to connect to the server.
//
// Find all latest examples here: https://opclabs.doc-that.com/files/onlinedocs/OPCLabs-OpcStudio/Latest/examples.html .
// OPC client, server and subscriber examples in C# on GitHub: https://github.com/OPCLabs/Examples-OPCStudio-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.NodeSpace;
using Timer = System.Timers.Timer;
namespace UAServerDocExamples._UAServerNode
{
class DataSubscriptionChanged
{
public static void Main1()
{
// Instantiate the server object.
// By default, the server will run on endpoint URL "opc.tcp://localhost:48040/".
var server = new EasyUAServer();
// Create a read-only data variable.
var random = new Random();
var dataVariable = UADataVariable.CreateIn(server.Objects, "SubscribeToThisVariable")
.ValueType<int>()
.Writable(false);
dataVariable.UseDataPolling = false; // Recommended, but not strictly necessary.
dataVariable.DataSubscriptionChanged += (sender, args) =>
{
switch (args.Action)
{
case UADataSubscriptionChangedAction.Add:
{
// Obtain the sampling interval from the data subscription.
int samplingInterval = args.DataSubscription.SamplingInterval;
Console.WriteLine($"Data subscription added, sampling interval: {samplingInterval}");
// Create a timer that will provide the data variable with a new data. In a real server the activity
// may also come from other sources.
var timer = new Timer { AutoReset = true, Interval = samplingInterval };
args.DataSubscription.State = timer;
// Set the read attribute data of the data variable to a random value whenever the timer interval elapses.
timer.Elapsed += (s, e) => args.DataSubscription.OnNext(random.Next());
// Start the subscription timer.
timer.Start();
break;
}
case UADataSubscriptionChangedAction.Remove:
{
Console.WriteLine("Data subscription removed");
// Dispose of the subscription timer (stopping it too).
var timer = (Timer)args.DataSubscription.State;
timer.Dispose();
break;
}
case UADataSubscriptionChangedAction.Modify:
{
int samplingInterval = args.DataSubscription.SamplingInterval;
Console.WriteLine($"Data subscription modified, sampling interval: {samplingInterval}");
// Change the interval of the subscription timer.
var timer = (Timer)args.DataSubscription.State;
timer.Interval = samplingInterval;
break;
}
}
args.Handled = true; // Do not forget to indicate that your code has handled the event.
};
// The read behavior of the data variable needs to be defined as well, separately from the data subscriptions.
dataVariable.ReadValueFunction(() => random.Next());
// Start the server.
Console.WriteLine("The server is starting...");
server.Start();
Console.WriteLine("The server is started.");
Console.WriteLine();
// Let the user decide when to stop.
Console.WriteLine("Press Enter to stop the server...");
Console.ReadLine();
// Stop the server.
Console.WriteLine("The server is stopping...");
server.Stop();
Console.WriteLine("The server is stopped.");
}
}
}
' This example shows how to implement own handling of data subscriptions.
' You can use any OPC UA client, including our Connectivity Explorer and OpcCmd utility, to connect to the server.
'
' 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 System
Imports OpcLabs.EasyOpc.UA
Imports OpcLabs.EasyOpc.UA.NodeSpace
Imports Timer = System.Timers.Timer
Namespace _UAServerNode
Partial Friend Class DataSubscriptionChanged
Shared Sub Main1()
' Instantiate the server object.
' By default, the server will run on endpoint URL "opc.tcp://localhost:48040/".
Dim server = New EasyUAServer()
' Create a read-only data variable.
Dim random = New Random()
Dim dataVariable = UADataVariable.CreateIn(server.Objects, "SubscribeToThisVariable") _
.ValueType(Of Integer)() _
.Writable(False)
dataVariable.UseDataPolling = False ' Recommended, but not strictly necessary.
AddHandler dataVariable.DataSubscriptionChanged, Sub(sender, args)
Select Case args.Action
Case UADataSubscriptionChangedAction.Add
' Obtain the sampling interval from the data subscription.
Dim samplingInterval As Integer = args.DataSubscription.SamplingInterval
Console.WriteLine($"Data subscription added, sampling interval: {samplingInterval}")
' Create a timer that will provide the data variable with a new data. In a real server the activity
' may also come from other sources.
Dim timer = New Timer With {.AutoReset = True, .Interval = samplingInterval}
args.DataSubscription.State = timer
' Set the read attribute data of the data variable to a random value whenever the timer interval elapses.
AddHandler timer.Elapsed, Sub(s, e) args.DataSubscription.OnNext(random.Next())
' Start the subscription timer.
timer.Start()
Case UADataSubscriptionChangedAction.Remove
Console.WriteLine("Data subscription removed")
' Dispose of the subscription timer (stopping it too).
Dim timer As Timer = CType(args.DataSubscription.State, Timer)
timer.Dispose()
Case UADataSubscriptionChangedAction.Modify
Dim samplingInterval As Integer = args.DataSubscription.SamplingInterval
Console.WriteLine($"Data subscription modified, sampling interval: {samplingInterval}")
' Change the interval of the subscription timer.
Dim timer As Timer = CType(args.DataSubscription.State, Timer)
timer.Interval = samplingInterval
End Select
End Sub
' The read behavior of the data variable needs to be defined as well, separately from the data subscriptions.
dataVariable.ReadValueFunction(Function() random.Next())
' Start the server.
Console.WriteLine("The server is starting...")
server.Start()
Console.WriteLine("The server is started.")
Console.WriteLine()
' Let the user decide when to stop.
Console.WriteLine("Press Enter to stop the server...")
Console.ReadLine()
' Stop the server.
Console.WriteLine("The server is stopping...")
server.Stop()
Console.WriteLine("The server is stopped.")
End Sub
End Class
End Namespace
