OPC UA : minimal code that browses the root node of a server

Question

I am using the OPC UA Foundation SDK to develop a small client. What would be the minimal C# code to:

• Connect to a server
• Browse the root node
• Print the immediate children's BrowseNames
• Quit?

I am given the server endpoint (no discovery), security None.

The code should make no use of config files, nor require a STA.

Any help on this would be more than appreciated.

Answer 1

Edit 4/2018:

The OPC UA .Net Standard Library is going asynchronous. See the updated sample.

Edit 9/2016:

Everyone should see the new OPC UA .Net Standard Library.

You can develop apps that run on all common platforms available today, including Linux, iOS, Android (via Xamarin) and Windows.

And you can find many samples, including a sample inspired by this post. Look for the folder SampleApplications/Samples/NetCoreConsoleClient.

Original post:

Help with homework, perhaps?

using Opc.Ua;   // Install-Package OPCFoundation.NetStandard.Opc.Ua
using Opc.Ua.Client;
using Opc.Ua.Configuration;
using System;
using System.Collections.Generic;
using System.Diagnostics;
using System.Net;

namespace MyHomework
{
  class Program
  {
    static void Main(string[] args)
    {

        Console.WriteLine("Step 1 - Create application configuration and certificate.");
        var config = new ApplicationConfiguration()
        {
            ApplicationName = "MyHomework",
            ApplicationUri = Utils.Format(@"urn:{0}:MyHomework", System.Net.Dns.GetHostName()),
            ApplicationType = ApplicationType.Client,
            SecurityConfiguration = new SecurityConfiguration {
                ApplicationCertificate = new CertificateIdentifier { StoreType = @"Directory", StorePath = @"%CommonApplicationData%\OPC Foundation\CertificateStores\MachineDefault", SubjectName="MyHomework" },
                TrustedIssuerCertificates = new CertificateTrustList { StoreType = @"Directory", StorePath = @"%CommonApplicationData%\OPC Foundation\CertificateStores\UA Certificate Authorities" },
                TrustedPeerCertificates = new CertificateTrustList { StoreType = @"Directory", StorePath = @"%CommonApplicationData%\OPC Foundation\CertificateStores\UA Applications" },
                RejectedCertificateStore = new CertificateTrustList { StoreType = @"Directory", StorePath = @"%CommonApplicationData%\OPC Foundation\CertificateStores\RejectedCertificates" },
                AutoAcceptUntrustedCertificates = true
            },
            TransportConfigurations = new TransportConfigurationCollection(),
            TransportQuotas = new TransportQuotas { OperationTimeout = 15000 },
            ClientConfiguration = new ClientConfiguration { DefaultSessionTimeout = 60000 },
            TraceConfiguration = new TraceConfiguration()
        };
        config.Validate(ApplicationType.Client).GetAwaiter().GetResult();
        if (config.SecurityConfiguration.AutoAcceptUntrustedCertificates)
        {
            config.CertificateValidator.CertificateValidation += (s, e) => { e.Accept = (e.Error.StatusCode == StatusCodes.BadCertificateUntrusted); };
        }

        var application = new ApplicationInstance
        {
            ApplicationName = "MyHomework",
            ApplicationType = ApplicationType.Client,
            ApplicationConfiguration = config
        };
        application.CheckApplicationInstanceCertificate(false, 2048).GetAwaiter().GetResult();

        var selectedEndpoint = CoreClientUtils.SelectEndpoint("opc.tcp://" + Dns.GetHostName() + ":48010", useSecurity: true, operationTimeout: 15000);

        Console.WriteLine($"Step 2 - Create a session with your server: {selectedEndpoint.EndpointUrl} ");
        using (var session = Session.Create(config, new ConfiguredEndpoint(null, selectedEndpoint, EndpointConfiguration.Create(config)), false, "", 60000, null, null).GetAwaiter().GetResult())
        {
            Console.WriteLine("Step 3 - Browse the server namespace.");
            ReferenceDescriptionCollection refs;
            Byte[] cp;
            session.Browse(null, null, ObjectIds.ObjectsFolder, 0u, BrowseDirection.Forward, ReferenceTypeIds.HierarchicalReferences, true, (uint)NodeClass.Variable | (uint)NodeClass.Object | (uint)NodeClass.Method, out cp, out refs);
            Console.WriteLine("DisplayName: BrowseName, NodeClass");
            foreach (var rd in refs)
            {
                Console.WriteLine("{0}: {1}, {2}", rd.DisplayName, rd.BrowseName, rd.NodeClass);
                ReferenceDescriptionCollection nextRefs;
                byte[] nextCp;
                session.Browse(null, null, ExpandedNodeId.ToNodeId(rd.NodeId, session.NamespaceUris), 0u, BrowseDirection.Forward, ReferenceTypeIds.HierarchicalReferences, true, (uint)NodeClass.Variable | (uint)NodeClass.Object | (uint)NodeClass.Method, out nextCp, out nextRefs);
                foreach (var nextRd in nextRefs)
                {
                    Console.WriteLine("+ {0}: {1}, {2}", nextRd.DisplayName, nextRd.BrowseName, nextRd.NodeClass);
                }
            }

            Console.WriteLine("Step 4 - Create a subscription. Set a faster publishing interval if you wish.");
            var subscription = new Subscription(session.DefaultSubscription) { PublishingInterval = 1000 };

            Console.WriteLine("Step 5 - Add a list of items you wish to monitor to the subscription.");
            var list = new List<MonitoredItem> { new MonitoredItem(subscription.DefaultItem) { DisplayName = "ServerStatusCurrentTime", StartNodeId = "i=2258" } };
            list.ForEach(i => i.Notification += OnNotification);
            subscription.AddItems(list);

            Console.WriteLine("Step 6 - Add the subscription to the session.");
            session.AddSubscription(subscription);
            subscription.Create();

            Console.WriteLine("Press any key to remove subscription...");
            Console.ReadKey(true);
        }

        Console.WriteLine("Press any key to exit...");
        Console.ReadKey(true);
    }

    private static void OnNotification(MonitoredItem item, MonitoredItemNotificationEventArgs e)
    {
        foreach (var value in item.DequeueValues())
        {
            Console.WriteLine("{0}: {1}, {2}, {3}", item.DisplayName, value.Value, value.SourceTimestamp, value.StatusCode);
        }
    }

  }
}