![](dotnetdiagramimages/OpcLabs_ServerOpcUA_OpcLabs_EasyOpc_UA_OperationModel_EasyUAClientSessionConnectionEventArgs.png)
'Declaration
<ExceptionContractAnnotationAttribute(True)> Public Class EasyUAClientSessionConnectionEventArgs Inherits System.EventArgs
'Usage
Dim instance As EasyUAClientSessionConnectionEventArgs
[ExceptionContractAnnotation(true)] public class EasyUAClientSessionConnectionEventArgs : System.EventArgs
[ExceptionContractAnnotation(true)] public ref class EasyUAClientSessionConnectionEventArgs : public System.EventArgs
You can obtain the current number of client sessions using the OpcLabs.EasyOpc.UA.Services.IEasyUAServerConnectionMonitoring.ClientSessionCount.
// This example shows how to monitor OPC UA client connections to the server. // 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 Microsoft.Extensions.DependencyInjection; using OpcLabs.EasyOpc.UA; using OpcLabs.EasyOpc.UA.NodeSpace; using OpcLabs.EasyOpc.UA.OperationModel; using OpcLabs.EasyOpc.UA.Services; namespace UAServerDocExamples._EasyUAServerConnectionMonitoring { class ClientSessions { 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(); // Define a data variable providing random integers. var random = new Random(); server.Add(new UADataVariable("MyDataVariable").ReadValueFunction(() => random.Next())); // Obtain the server connection monitoring service. IEasyUAServerConnectionMonitoring serverConnectionMonitoring = server.GetService<IEasyUAServerConnectionMonitoring>(); if (serverConnectionMonitoring is null) { Console.WriteLine("The server connection monitoring service is not available."); return; } // Hook events. serverConnectionMonitoring.ClientSessionConnected += ServerConnectionMonitoringOnClientSessionConnected; serverConnectionMonitoring.ClientSessionDisconnected += ServerConnectionMonitoringOnClientSessionDisconnected; // 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."); } // Event handler for the ClientSessionConnected event. static private void ServerConnectionMonitoringOnClientSessionConnected( object sender, EasyUAClientSessionConnectionEventArgs e) { var serverConnectionMonitoring = (IEasyUAServerConnectionMonitoring)sender; Console.WriteLine( $"A client session has connected to endpoint \"{e.EndpointUrlString}\". " + $"There is now {serverConnectionMonitoring.ClientSessionCount} client session(s)."); } // Event handler for the ClientSessionDisconnected event. static private void ServerConnectionMonitoringOnClientSessionDisconnected( object sender, EasyUAClientSessionConnectionEventArgs e) { var serverConnectionMonitoring = (IEasyUAServerConnectionMonitoring)sender; Console.WriteLine( $"A client session has disconnected from endpoint \"{e.EndpointUrlString}\". " + $"There is now {serverConnectionMonitoring.ClientSessionCount} client session(s)."); } } }
' This example shows how to monitor OPC UA client connections to the server. ' 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 Microsoft.Extensions.DependencyInjection Imports OpcLabs.EasyOpc.UA Imports OpcLabs.EasyOpc.UA.NodeSpace Imports OpcLabs.EasyOpc.UA.OperationModel Imports OpcLabs.EasyOpc.UA.Services Namespace _EasyUAServerConnectionMonitoring Partial Friend Class ClientSessions Shared Sub Main1() ' Instantiate the server object. ' By default, the server will run on endpoint URL "opc.tcp://localhost:48040/". Dim server = New EasyUAServer() ' Define a data variable providing random integers. Dim random = New Random() server.Add(New UADataVariable("MyDataVariable").ReadValueFunction(Function() random.Next())) ' Obtain the server connection monitoring service. Dim serverConnectionMonitoring As IEasyUAServerConnectionMonitoring = server.GetService(Of IEasyUAServerConnectionMonitoring) If serverConnectionMonitoring Is Nothing Then Console.WriteLine("The server connection monitoring service is not available.") Exit Sub End If ' Hook events. AddHandler serverConnectionMonitoring.ClientSessionConnected, AddressOf ServerConnectionMonitoringOnClientSessionConnected AddHandler serverConnectionMonitoring.ClientSessionDisconnected, AddressOf ServerConnectionMonitoringOnClientSessionDisconnected ' 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 ' Event handler for the ClientSessionConnected event. Private Shared Sub ServerConnectionMonitoringOnClientSessionConnected(ByVal sender As Object, ByVal e As EasyUAClientSessionConnectionEventArgs) Dim serverConnectionMonitoring As IEasyUAServerConnectionMonitoring = sender Console.WriteLine( $"A client session has connected to endpoint ""{e.EndpointUrlString}"". " + $"There is now {serverConnectionMonitoring.ClientSessionCount} client session(s).") End Sub ' Event handler for the ClientSessionDisconnected event. Private Shared Sub ServerConnectionMonitoringOnClientSessionDisconnected(ByVal sender As Object, ByVal e As EasyUAClientSessionConnectionEventArgs) Dim serverConnectionMonitoring As IEasyUAServerConnectionMonitoring = sender Console.WriteLine( $"A client session has disconnected from endpoint ""{e.EndpointUrlString}"". " + $"There is now {serverConnectionMonitoring.ClientSessionCount} client session(s).") End Sub End Class End Namespace
// A fully functional OPC UA demo server running in Windows Forms host. // // 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.Linq; using System.Windows.Forms; using Microsoft.Extensions.DependencyInjection; using OpcLabs.EasyOpc.UA; using OpcLabs.EasyOpc.UA.Forms.Application; using OpcLabs.EasyOpc.UA.OperationModel; using OpcLabs.EasyOpc.UA.Services; using UAServerDemoLibrary; namespace UAServerWindowsFormsDemo { public partial class MainForm : Form { public MainForm() { InitializeComponent(); // Instantiating the EasyUAServer here, and not inline where the field is declared, is important for it to // acquire the proper synchronization context. _server = new EasyUAServer(); } private void Form1_Load(object sender, System.EventArgs e) { // Extend the form's system menu by a command for OPC UA application management. EasyUAFormsApplication.Instance.AddToSystemMenu(this); // Define various nodes. DataNodes.AddToParent(_server.Objects); DemoNodes.AddToParent(_server.Objects); // Hook events to the server object. _server.EndpointStateChanged += ServerOnEndpointStateChanged; // Obtain the server connection monitoring service. IEasyUAServerConnectionMonitoring serverConnectionMonitoring = _server.GetService<IEasyUAServerConnectionMonitoring>(); if (!(serverConnectionMonitoring is null)) { // Hook events to the connection monitoring service. serverConnectionMonitoring.ClientSessionConnected += ServerConnectionMonitoringOnClientSessionConnected; serverConnectionMonitoring.ClientSessionDisconnected += ServerConnectionMonitoringOnClientSessionDisconnected; } _server.Start(); } private void Form1_FormClosing(object sender, FormClosingEventArgs e) { _server.Stop(); } private void ServerOnEndpointStateChanged(object sender, EasyUAServerEndpointStateChangedEventArgs e) { // Note that since we have created the EasyUAServer on the UI thread, we can access the UI controls in its // event handlers directly, because the events are raised using the synchronization context acquired at time of // the creation. string endpointUrlString = e.EndpointUrlString; ListViewItem listViewItem = endpointStateListView.Items.Cast<ListViewItem>().FirstOrDefault(item => item.Text == endpointUrlString); if (listViewItem is null) { listViewItem = new ListViewItem(endpointUrlString); endpointStateListView.Items.Add(listViewItem); listViewItem.SubItems.Add(""); listViewItem.SubItems.Add(""); } listViewItem.SubItems[1].Text = e.ConnectionState.ToString(); listViewItem.SubItems[2].Text = e.Exception?.Message ?? ""; } private void ServerConnectionMonitoringOnClientSessionConnected(object sender, EasyUAClientSessionConnectionEventArgs e) { // Note that since we have created the EasyUAServer on the UI thread, we can access the UI controls in its // event handlers directly, because the events are raised using the synchronization context acquired at time of // the creation. var listViewItem = new ListViewItem(e.SessionId.Identifier.ToString()); listViewItem.SubItems.Add(e.SessionName); connectionsListView.Items.Add(listViewItem); } private void ServerConnectionMonitoringOnClientSessionDisconnected(object sender, EasyUAClientSessionConnectionEventArgs e) { // Note that since we have created the EasyUAServer on the UI thread, we can access the UI controls in its // event handlers directly, because the events are raised using the synchronization context acquired at time of // the creation. string identifierString = e.SessionId.Identifier.ToString(); ListViewItem listViewItem = connectionsListView.Items.Cast<ListViewItem>().FirstOrDefault(item => item.Text == identifierString); if (!(listViewItem is null)) connectionsListView.Items.Remove(listViewItem); } private readonly EasyUAServer _server; } }
' A fully functional OPC UA demo server running in Windows Forms host. ' ' 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.Linq Imports System.Windows.Forms Imports Microsoft.Extensions.DependencyInjection Imports OpcLabs.EasyOpc.UA Imports OpcLabs.EasyOpc.UA.Forms.Application Imports OpcLabs.EasyOpc.UA.OperationModel Imports OpcLabs.EasyOpc.UA.Services Imports UAServerDemoLibrary Public Class MainForm Sub New() InitializeComponent() ' Instantiating the EasyUAServer here, and not inline where the field is declared, is important for it to ' acquire the proper synchronization context. _server = New EasyUAServer() End Sub Private Sub MainForm_Load(sender As Object, e As EventArgs) Handles MyBase.Load ' Extend the form's system menu by a command for OPC UA application management. EasyUAFormsApplication.Instance.AddToSystemMenu(Me) ' Define various nodes. DataNodes.AddToParent(_server.Objects) DemoNodes.AddToParent(_server.Objects) ' Hook events to the server object. AddHandler _server.EndpointStateChanged, AddressOf ServerOnEndpointStateChanged ' Obtain the server connection monitoring service. Dim serverConnectionMonitoring As IEasyUAServerConnectionMonitoring = _server.GetService(Of IEasyUAServerConnectionMonitoring)() If (Not (serverConnectionMonitoring Is Nothing)) Then ' Hook events to the connection monitoring service. AddHandler serverConnectionMonitoring.ClientSessionConnected, AddressOf ServerConnectionMonitoringOnClientSessionConnected AddHandler serverConnectionMonitoring.ClientSessionDisconnected, AddressOf ServerConnectionMonitoringOnClientSessionDisconnected End If _server.Start() End Sub Private ReadOnly _server As EasyUAServer Private Sub MainForm_FormClosing(sender As Object, e As FormClosingEventArgs) Handles MyBase.FormClosing _server.Stop() End Sub Private Sub ServerOnEndpointStateChanged(sender As Object, e As EasyUAServerEndpointStateChangedEventArgs) ' Note that since we have created the EasyUAServer on the UI thread, we can access the UI controls in its ' event handlers directly, because the events are raised using the synchronization context acquired at time of ' the creation. Dim endpointUrlString As String = e.EndpointUrlString Dim listViewItem As ListViewItem = endpointStateListView.Items.Cast(Of ListViewItem)().FirstOrDefault(Function(item) _ item.Text = endpointUrlString) If (listViewItem Is Nothing) Then listViewItem = New ListViewItem(endpointUrlString) endpointStateListView.Items.Add(listViewItem) listViewItem.SubItems.Add("") listViewItem.SubItems.Add("") End If listViewItem.SubItems(1).Text = e.ConnectionState.ToString() listViewItem.SubItems(2).Text = If(e.Exception?.Message, "") End Sub Private Sub ServerConnectionMonitoringOnClientSessionConnected(sender As Object, e As EasyUAClientSessionConnectionEventArgs) ' Note that since we have created the EasyUAServer on the UI thread, we can access the UI controls in its ' event handlers directly, because the events are raised using the synchronization context acquired at time of ' the creation. Dim listViewItem = New ListViewItem(e.SessionId.Identifier.ToString()) listViewItem.SubItems.Add(e.SessionName) connectionsListView.Items.Add(listViewItem) End Sub Private Sub ServerConnectionMonitoringOnClientSessionDisconnected(sender As Object, e As EasyUAClientSessionConnectionEventArgs) ' Note that since we have created the EasyUAServer on the UI thread, we can access the UI controls in its ' event handlers directly, because the events are raised using the synchronization context acquired at time of ' the creation. Dim identifierString As String = e.SessionId.Identifier.ToString() Dim listViewItem As ListViewItem = connectionsListView.Items.Cast(Of ListViewItem)().FirstOrDefault(Function(item) _ item.Text = identifierString) If (Not (listViewItem Is Nothing)) Then connectionsListView.Items.Remove(listViewItem) End If End Sub End Class
System.Object
System.EventArgs
OpcLabs.EasyOpc.UA.OperationModel.EasyUAClientSessionConnectionEventArgs