// This example shows how to subscribe to changes of multiple monitored items // and display each change, identifying the different subscriptions by an // object. using System; using System.Threading; using OpcLabs.EasyOpc.UA; using OpcLabs.EasyOpc.UA.OperationModel; namespace UADocExamples._EasyUAClient { partial class SubscribeMultipleMonitoredItems { class CustomObject { public CustomObject(string name) { Name = name; } public string Name { get; } } public static void StateAsObject() { UAEndpointDescriptor endpointDescriptor = "opc.tcp://opcua.demo-this.com:51210/UA/SampleServer"; // or "http://opcua.demo-this.com:51211/UA/SampleServer" (not in .NET Standard) // or "https://opcua.demo-this.com:51212/UA/SampleServer/" // Instantiate the client object and hook events var client = new EasyUAClient(); client.DataChangeNotification += ClientOnDataChangeNotification_StateAsObject; Console.WriteLine("Subscribing..."); int[] handleArray = client.SubscribeMultipleMonitoredItems(new[] { new EasyUAMonitoredItemArguments(null, endpointDescriptor, "nsu=http://test.org/UA/Data/;i=10845", 1000) {State = new CustomObject("First")}, // A custom object that corresponds to the subscription new EasyUAMonitoredItemArguments(null, endpointDescriptor, "nsu=http://test.org/UA/Data/;i=10853", 1000) {State = new CustomObject("Second")}, // A custom object that corresponds to the subscription new EasyUAMonitoredItemArguments(null, endpointDescriptor, "nsu=http://test.org/UA/Data/;i=10855", 1000) {State = new CustomObject("Third")}, // A custom object that corresponds to the subscription }); for (int i = 0; i < handleArray.Length; i++) Console.WriteLine($"handleArray[{i}]: {handleArray[i]}"); Console.WriteLine("Processing monitored item changed events for 10 seconds..."); Thread.Sleep(10 * 1000); Console.WriteLine("Unsubscribing..."); client.UnsubscribeAllMonitoredItems(); Console.WriteLine("Waiting for 5 seconds..."); Thread.Sleep(5 * 1000); Console.WriteLine("Finished."); } static void ClientOnDataChangeNotification_StateAsObject(object sender, EasyUADataChangeNotificationEventArgs eventArgs) { // Obtain the custom object we have passed in. var stateAsObject = (CustomObject) eventArgs.Arguments.State; // Display the data if (eventArgs.Succeeded) Console.WriteLine($"{stateAsObject.Name}: {eventArgs.AttributeData}"); else Console.WriteLine($"{stateAsObject.Name} *** Failure: {eventArgs.ErrorMessageBrief}"); }

// This example shows that either a single client object, or multiple client objects can be used to read values from two // servers. using System; using OpcLabs.EasyOpc.UA; using OpcLabs.EasyOpc.UA.OperationModel; namespace UADocExamples._EasyUAClient { partial class ReadValue { public static void MultipleServers() { // Define which servers we will work with. UAEndpointDescriptor endpointDescriptor1 = "opc.tcp://opcua.demo-this.com:51210/UA/SampleServer"; // or "http://opcua.demo-this.com:51211/UA/SampleServer" (not in .NET Standard) // or "https://opcua.demo-this.com:51212/UA/SampleServer/" UAEndpointDescriptor endpointDescriptor2 = "opc.tcp://opcua.demo-this.com:62544/Quickstarts/AlarmConditionServer"; // Part 1: Use a single client object. // This demonstrates the fact the the client objects do *not* represent connections to individual servers. // Instead, they are able to maintain connections to multiple servers internally. API method calls on the client // object include the server's endpoint descriptor in their arguments, so you can specify a different endpoint // with each operation. Console.WriteLine(); // Instantiate the client object var client = new EasyUAClient(); Console.WriteLine("Obtaining values of nodes using a single client object..."); object value1, value2; try { // The node Id we are reading returns the product name of the server. value1 = client.ReadValue(endpointDescriptor1, "nsu=http://opcfoundation.org/UA/ ;i=2261"); value2 = client.ReadValue(endpointDescriptor2, "nsu=http://opcfoundation.org/UA/ ;i=2261"); // Note: For efficiency (reading from the two servers in parallel), it would be better to use the // ReadMultipleValues method here, but this example is made for code clarity. } catch (UAException uaException) { Console.WriteLine("*** Failure: {0}", uaException.GetBaseException().Message); return; } // Display results Console.WriteLine("value1: {0}", value1); Console.WriteLine("value2: {0}", value2); // Part 2: Use multiple client objects. // This demonstrates the fact that it is also possible to use multiple client objects, and on the OPC side, the // behavior will be the same as if you had used a single client object. Multiple client objects consume somewhat // more resources on the client side, but they come handy if, for example, // - you cannot easily pass around the single pre-created client object to various parts in your code, or // - you are using subscriptions and you want to hook separate event handlers for different purposes, or // - you need to set something in the instance parameters of the client object differently for different // connections. Console.WriteLine(); // Instantiate the client object2 var client1 = new EasyUAClient(); var client2 = new EasyUAClient(); Console.WriteLine("Obtaining values of nodes using a single client object..."); try { // The node Id we are reading returns the product name of the server. value1 = client1.ReadValue(endpointDescriptor1, "nsu=http://opcfoundation.org/UA/ ;i=2261"); value2 = client2.ReadValue(endpointDescriptor2, "nsu=http://opcfoundation.org/UA/ ;i=2261"); } catch (UAException uaException) { Console.WriteLine("*** Failure: {0}", uaException.GetBaseException().Message); return; } // Display results Console.WriteLine("value1: {0}", value1); Console.WriteLine("value2: {0}", value2); // Example output: // //Obtaining values of nodes using a single client object... //value1: OPC UA SDK Samples //value2: OPC UA Workshop Samples // //Obtaining values of nodes using a single client object... //value1: OPC UA SDK Samples //value2: OPC UA Workshop Samples } } }