// @nuget: Workstation.UaClient -version 2.4.0

using System;

using System.Threading.Tasks;

using Workstation.ServiceModel.Ua;

using Workstation.ServiceModel.Ua.Channels;

public class Program

{

    /// <summary>

    /// Connects to server and browses ObjectsFolder. 

    /// From a given start node, Browse returns the References of the node. 

    /// There are many options to filter references by type and direction.

    /// </summary>

    public static async Task Main()

    {

        // describe this client application.

        var clientDescription = new ApplicationDescription

        {

            ApplicationName = "Workstation.UaClient.FeatureTests",

            ApplicationUri = $"urn:{System.Net.Dns.GetHostName()}:Workstation.UaClient.FeatureTests",

            ApplicationType = ApplicationType.Client

        };

​

        // create a 'UaTcpSessionChannel', a client-side channel that opens a 'session' with the server.

        var channel = new UaTcpSessionChannel(

            clientDescription,

            null, // no x509 certificates

            new AnonymousIdentity(), // no user identity

            "opc.tcp://opcua.rocks:4840", // the public endpoint of a server at opcua.rocks.

            SecurityPolicyUris.None); // no encryption

        try

        {

            // try opening a session and reading a few nodes.

            await channel.OpenAsync();

​

            Console.WriteLine($"Opened session with endpoint '{channel.RemoteEndpoint.EndpointUrl}'.");

            Console.WriteLine($"SecurityPolicy: '{channel.RemoteEndpoint.SecurityPolicyUri}'.");

            Console.WriteLine($"SecurityMode: '{channel.RemoteEndpoint.SecurityMode}'.");

            Console.WriteLine($"UserIdentityToken: '{channel.UserIdentity}'.");

​

            // build a BrowseRequest. See 'OPC UA Spec Part 4' section 5.8.2

            var browseRequest = new BrowseRequest {

                NodesToBrowse = new[] {

                    new BrowseDescription {

                        // start from this nodeid. You can use: NodeId.Parse("ns=1;i=50001") 

                        NodeId = NodeId.Parse(ObjectIds.ObjectsFolder),

                        // include just 'Forward' references

                        BrowseDirection = BrowseDirection.Forward,

                        // include 'HierarchicalReferences'

                        ReferenceTypeId = NodeId.Parse(ReferenceTypeIds.HierarchicalReferences),

                        // include 'HierarchicalReferences' and all subtypes of 'HierarchicalReferences'

                        IncludeSubtypes = true,

                        // include all classes of target node

                        NodeClassMask = (uint)NodeClass.Unspecified,

                        // return reference descriptions with all the fields filled out

                        ResultMask = (uint)BrowseResultMask.All,

                    }

                },

                RequestedMaxReferencesPerNode = 1000

            };

​

            // send the request to the server

            var browseResponse = await channel.BrowseAsync(browseRequest).ConfigureAwait(false);

​

            Console.WriteLine("\n+ Objects, Object, i=85");

​

            foreach (var rd in browseResponse.Results[0].References)

            {

                Console.WriteLine($"   + {rd.DisplayName}, {rd.NodeClass}, {rd.NodeId}");

            }

​

            // it is good practice to be prepared to receive a continuationPoint. 

            // ContinuationPoints are returned when the server has more information

            // than can be delivered in one response.

            // To test this code, you can reduce the above RequestedMaxReferencesPerNode

            // to 1.

            var cp = browseResponse.Results[0].ContinuationPoint;

            while (cp != null)

            {

                var browseNextRequest = new BrowseNextRequest { ContinuationPoints = new[] { cp }, ReleaseContinuationPoints = false };

                var browseNextResponse = await channel.BrowseNextAsync(browseNextRequest);

​

                foreach (var rd in browseNextResponse.Results[0].References)

                {

                    Console.WriteLine($"   + {rd.DisplayName}, {rd.NodeClass}, {rd.NodeId}");

                }

                cp = browseNextResponse.Results[0].ContinuationPoint;

            }

​

            Console.WriteLine($"\nClosing session '{channel.SessionId}'.");

            await channel.CloseAsync();

        }

        catch(Exception ex)

        {

            await channel.AbortAsync();

            Console.WriteLine(ex.Message);

        }

    }

}