OPC Studio User's Guide and Reference
IEasyUAGlobalDiscoveryClient Interface
Members  Example 



OpcLabs.EasyOpcUA Assembly > OpcLabs.EasyOpc.UA.Gds Namespace : IEasyUAGlobalDiscoveryClient Interface
Provides access to information model of an OPC UA Global Discovery Server (GDS).
Syntax
'Declaration
 

<ComVisibleAttribute(False)>
<ExceptionContractAnnotationAttribute(True)>
<ExceptionContractVerificationAttribute(True)>
Public Interface IEasyUAGlobalDiscoveryClient 
   Inherits OpcLabs.EasyOpc.UA.IEasyUASpecializedClient, System.IServiceProvider 
'Usage
 

Dim instance As IEasyUAGlobalDiscoveryClient
[ComVisible(false)]
[ExceptionContractAnnotation(true)]
[ExceptionContractVerification(true)]
public interface IEasyUAGlobalDiscoveryClient : OpcLabs.EasyOpc.UA.IEasyUASpecializedClient, System.IServiceProvider  
[ComVisible(false)]
[ExceptionContractAnnotation(true)]
[ExceptionContractVerification(true)]
public interface class IEasyUAGlobalDiscoveryClient : public OpcLabs.EasyOpc.UA.IEasyUASpecializedClient, System.IServiceProvider
Remarks

This interface contains methods to communicate with the OPC UA Global Discovery Server (GDS) using its information model for global discovery, making the work of assembling the proper OPC UA method parameters and retrieving the results. The methods allow querying for applications and/or servers, and registering, unregistering or updating application registrations in the GDS.

Only the global discovery aspect of the GDS information is covered by this interface. Certificate management (CM), key credential management, and authorization services are treated separately.

In the OPC UA specifications, the functionality covered by this type is described in Part 12: Discovery and Global Services, in the Global Discovery Server section.

You can obtain this interface e.g.:

Before deciding to use methods provided by this specialized client, it is recommended that you have a look at the OpcLabs.EasyOpc.UA.Application.IEasyUAClientServerApplication service, available from System.IServiceProvider.GetService(System.Type) method from the OpcLabs.EasyOpc.UA.IEasyUAClient interface. The client application service works on higher level, and conveniently combines several methods together to achieve the typically needed functionality related to GDS and certificate management in OPC UA.

 

The OPC UA Global Discovery Client is a specialized OPC UA client object for global discovery. In the OPC UA specifications, the functionality covered by this type is described in Part 12: Discovery and Global Services, in the Global Discovery Server section.

This specialized client object can be derived from IEasyUAClient Interface using the AsGlobalDiscoveryClient Extension Method, or it can be created standalone as EasyUAGlobalDiscoveryClient Component.

This interface contains methods to communicate with the OPC UA Global Discovery Server (GDS) using its information model for global discovery, making the work of assembling the proper OPC UA method parameters and retrieving the results. The methods allow querying for applications and/or servers, and registering, un-registering or updating application registrations in the GDS. Only the global discovery aspect of the GDS information is covered by this interface. Certificate management (CM), key credential management, and authorization services are treated separately.

Before deciding to use methods provided by this specialized client, it is recommended that you have a look at the IEasyUAClientServerApplication service (see OPC UA Client-Server Application Service), available from IServiceProvider.GetService method from the IEasyUAClient interface. The client application service works on higher level, and conveniently combines several methods together to achieve the typically needed functionality related to GDS and certificate management in OPC UA.

Available methods are:

The features discussed here, or some of them, may not be available in all editions of the product. Check the OPC Data Client Product Editions page for differences between the editions. The trial license has all features enabled (and is limited in period for which it provides valid data), but licenses for specific commercial editions may have functionality limitations.

Example

.NET

// Shows how to check if an application needs to update its certificate.
//
// Find all latest examples here: https://opclabs.doc-that.com/files/onlinedocs/OPCLabs-OpcStudio/Latest/examples.html .
// OPC client and subscriber examples in C# on GitHub: https://github.com/OPCLabs/Examples-QuickOPC-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.AddressSpace;
using OpcLabs.EasyOpc.UA.Application;
using OpcLabs.EasyOpc.UA.Extensions;
using OpcLabs.EasyOpc.UA.Gds;
using OpcLabs.EasyOpc.UA.OperationModel;

namespace UADocExamples.Gds._EasyUACertificateManagementClient
{
    class GetCertificateStatus
    {
        public static void Main1()
        {
            // Define which GDS we will work with.
            UAEndpointDescriptor gdsEndpointDescriptor = 
                ((UAEndpointDescriptor)"opc.tcp://opcua.demo-this.com:58810/GlobalDiscoveryServer")
                .WithUserNameIdentity("appadmin", "demo");

            // Register our client application with the GDS, so that we obtain an application ID that we need later.
            // Obtain the application interface.
            EasyUAApplication application = EasyUAApplication.Instance;
            UANodeId applicationId;
            try
            {
                applicationId = application.RegisterToGds(gdsEndpointDescriptor);
            }
            catch (UAException uaException)
            {
                Console.WriteLine("*** Failure: {0}", uaException.GetBaseException().Message);
                return;
            }
            Console.WriteLine("Application ID: {0}", applicationId);

            // Instantiate the certificate management client object
            var certificateManagementClient = new EasyUACertificateManagementClient();

            // Check if the application needs to update its certificate.
            bool updateRequired;
            try
            {
                updateRequired = certificateManagementClient.GetCertificateStatus(gdsEndpointDescriptor, applicationId,
                    UANodeId.Null, UANodeId.Null);
            }
            catch (UAException uaException)
            {
                Console.WriteLine("*** Failure: {0}", uaException.GetBaseException().Message);
                return;
            }

            // Display results
            Console.WriteLine("Update required: {0}", updateRequired);
        }


        // Example output:
        //Application ID: nsu=http://opcfoundation.org/UA/GDS/applications/ ;ns=2;g=aec94459-f513-4979-8619-8383555fca61
        //Update required: False
    }
}

' Shows how to check if an application needs to update its certificate.
'
' 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 Microsoft.Extensions.DependencyInjection
Imports OpcLabs.EasyOpc.UA
Imports OpcLabs.EasyOpc.UA.AddressSpace
Imports OpcLabs.EasyOpc.UA.Application
Imports OpcLabs.EasyOpc.UA.Application.ComTypes
Imports OpcLabs.EasyOpc.UA.Extensions
Imports OpcLabs.EasyOpc.UA.Gds
Imports OpcLabs.EasyOpc.UA.OperationModel

Namespace Gds._EasyUACertificateManagementClient
    Friend Class GetCertificateStatus
        Public Shared Sub Main1()

            ' Define which GDS we will work with.
            Dim gdsEndpointDescriptor As UAEndpointDescriptor =
                New UAEndpointDescriptor("opc.tcp://opcua.demo-this.com:58810/GlobalDiscoveryServer") _
                .WithUserNameIdentity("appadmin", "demo")

            ' Register our client application with the GDS, so that we obtain an application ID that we need later.
            ' Obtain the application interface.
            Dim application = EasyUAApplication.Instance

            ' Create an application registration in the GDS, assigning it a new application ID.
            Dim applicationId As UANodeId
            Try
                applicationId = application.RegisterToGds(gdsEndpointDescriptor)
            Catch uaException As UAException
                Console.WriteLine("*** Failure: {0}", uaException.GetBaseException.Message)
                Exit Sub
            End Try

            ' Instantiate the certificate management client object
            Dim certificateManagementClient = New EasyUACertificateManagementClient()

            ' Check if the application needs to update its certificate.
            Dim updateRequired As Boolean
            Try
                updateRequired = certificateManagementClient.GetCertificateStatus(gdsEndpointDescriptor, applicationId,
                    UANodeId.Null, UANodeId.Null)
            Catch uaException As UAException
                Console.WriteLine("*** Failure: {0}", uaException.GetBaseException.Message)
                Exit Sub
            End Try

            ' Display results
            Console.WriteLine("Update required: {0}", updateRequired)
        End Sub
    End Class
End Namespace

COM

// Shows how to check if an application needs to update its certificate.
//
// Find all latest examples here: https://opclabs.doc-that.com/files/onlinedocs/OPCLabs-OpcStudio/Latest/examples.html .
// OPC client and subscriber examples in Object Pascal (Delphi) on GitHub: https://github.com/OPCLabs/Examples-QuickOPC-OP .
// 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.

class procedure GetCertificateStatus.Main;
var
  Application: TEasyUAApplication;
  ApplicationId: _UANodeId;
  CertificateManagementClient: OpcLabs_EasyOpcUA_TLB._EasyUACertificateManagementClient;
  GdsEndpointDescriptor: _UAEndpointDescriptor;
  NullNodeId: _UANodeId;
  UpdateRequired: boolean;
begin
  // Define which GDS we will work with.
  GdsEndpointDescriptor := CoUAEndpointDescriptor.Create;
  GdsEndpointDescriptor.UrlString := 'opc.tcp://opcua.demo-this.com:58810/GlobalDiscoveryServer';
  GdsEndpointDescriptor.UserIdentity.UserNameTokenInfo.UserName := 'appadmin';
  GdsEndpointDescriptor.UserIdentity.UserNameTokenInfo.Password := 'demo';

  // Register our client application with the GDS, so that we obtain an application ID that we need later.
  // Obtain the application interface.
  Application := TEasyUAApplication.Create(nil);

  // Create an application registration in the GDS, assigning it a new application ID.
  try
    ApplicationId := Application.RegisterToGds(GdsEndpointDescriptor);
  except
    on E: EOleException do
    begin
      WriteLn(Format('*** Failure: %s', [E.GetBaseException.Message]));
    end;
  end;

  WriteLn('Application ID: ', ApplicationId.ToString);

  // Instantiate the certificate management client object
  CertificateManagementClient := CoEasyUACertificateManagementClient.Create;

  // Check if the application needs to update its certificate.
  NullNodeId := CoUANodeId.Create;
  UpdateRequired := false;
  try
    UpdateRequired := CertificateManagementClient.GetCertificateStatus(GdsEndpointDescriptor, ApplicationId, NullNodeId, NullNodeId);
  except
    on E: EOleException do
    begin
      WriteLn(Format('*** Failure: %s', [E.GetBaseException.Message]));
    end;
  end;

  // Display results
  WriteLn('Update required: ', UpdateRequired);

  // Example output:
  //Application ID: nsu=http://opcfoundation.org/UA/GDS/applications/ ;ns=2;g=aec94459-f513-4979-8619-8383555fca61
  //Update required: FALSE

end;

REM Shows how to check if an application needs to update its certificate.
REM
REM Find all latest examples here: https://opclabs.doc-that.com/files/onlinedocs/OPCLabs-OpcStudio/Latest/examples.html .
REM OPC client and subscriber examples in Visual Basic on GitHub: https://github.com/OPCLabs/Examples-QuickOPC-VB .
REM Missing some example? Ask us for it on our Online Forums, https://www.opclabs.com/forum/index ! You do not have to own
REM a commercial license in order to use Online Forums, and we reply to every post.

Private Sub EasyUACertificateManagementClient_GetCertificateStatus_Main_Command_Click()
    OutputText = ""
        
    ' Define which GDS we will work with.
    Dim gdsEndpointDescriptor As New UAEndpointDescriptor
    gdsEndpointDescriptor.UrlString = "opc.tcp://opcua.demo-this.com:58810/GlobalDiscoveryServer"
    gdsEndpointDescriptor.UserIdentity.UserNameTokenInfo.UserName = "appadmin"
    gdsEndpointDescriptor.UserIdentity.UserNameTokenInfo.Password = "demo"
    
    ' Register our client application with the GDS, so that we obtain an application ID that we need later.
    ' Obtain the application interface
    Dim Application As New EasyUAApplication
    
    ' Create an application registration in the GDS, assigning it a new application ID.
    On Error Resume Next
    Dim applicationId As UANodeId
    Set applicationId = Application.RegisterToGds(gdsEndpointDescriptor)
    If Err.Number <> 0 Then
        OutputText = OutputText & "*** Failure: " & Err.Source & ": " & Err.Description & vbCrLf
        Exit Sub
    End If
    On Error GoTo 0

    OutputText = OutputText & "Application ID: " & applicationId & vbCrLf

    ' Instantiate the certificate management client object
    Dim certificateManagementClient As New EasyUACertificateManagementClient
    
    ' Check if the application needs to update its certificate.
    Dim nullNodeId As New UANodeId
    Dim updateRequired As Boolean: updateRequired = False
    On Error Resume Next
    updateRequired = certificateManagementClient.GetCertificateStatus(gdsEndpointDescriptor, applicationId, nullNodeId, nullNodeId)
    If Err.Number <> 0 Then
        OutputText = OutputText & "*** Failure: " & Err.Source & ": " & Err.Description & vbCrLf
        Exit Sub
    End If
    On Error GoTo 0

    ' Display results
    OutputText = OutputText & "Update required: " & updateRequired & vbCrLf

    ' Example output:
    'Application ID: nsu=http://opcfoundation.org/UA/GDS/applications/ ;ns=2;g=aec94459-f513-4979-8619-8383555fca61
    'Update required: FALSE
End Sub

Rem Shows how to check if an application needs to update its certificate.
Rem
Rem Find all latest examples here: https://opclabs.doc-that.com/files/onlinedocs/OPCLabs-OpcStudio/Latest/examples.html .
Rem OPC client and subscriber examples in VBScript on GitHub: https://github.com/OPCLabs/Examples-QuickOPC-VBScript .
Rem Missing some example? Ask us for it on our Online Forums, https://www.opclabs.com/forum/index ! You do not have to own
Rem a commercial license in order to use Online Forums, and we reply to every post.

Option Explicit

' Define which GDS we will work with.
Dim GdsEndpointDescriptor: Set GdsEndpointDescriptor = CreateObject("OpcLabs.EasyOpc.UA.UAEndpointDescriptor")
GdsEndpointDescriptor.UrlString = "opc.tcp://opcua.demo-this.com:58810/GlobalDiscoveryServer"
GdsEndpointDescriptor.UserIdentity.UserNameTokenInfo.UserName = "appadmin"
GdsEndpointDescriptor.UserIdentity.UserNameTokenInfo.Password = "demo"

' Register our client application with the GDS, so that we obtain an application ID that we need later.
' Obtain the application interface.
Dim Application: Set Application = CreateObject("OpcLabs.EasyOpc.UA.Application.EasyUAApplication")
On Error Resume Next
Dim ApplicationId: Set ApplicationId = Application.RegisterToGds(GdsEndpointDescriptor)
If Err.Number <> 0 Then
    WScript.Echo "*** Failure: " & Err.Source & ": " & Err.Description
    WScript.Quit
End If
On Error Goto 0
WScript.Echo "Application ID: " & ApplicationId

' Instantiate the certificate management client object
Dim CertificateManagementClient: Set CertificateManagementClient = _
    CreateObject("OpcLabs.EasyOpc.UA.Gds.EasyUACertificateManagementClient")

' Check if the application needs to update its certificate.
Dim NullNodeId: Set NullNodeId = CreateObject("OpcLabs.EasyOpc.UA.AddressSpace.UANodeId")
On Error Resume Next
Dim UpdateRequired: UpdateRequired = CertificateManagementClient.GetCertificateStatus( _
    GdsEndpointDescriptor, ApplicationId, NullNodeId, NullNodeId)
If Err.Number <> 0 Then
    WScript.Echo "*** Failure: " & Err.Source & ": " & Err.Description
    WScript.Quit
End If
On Error Goto 0

' Display results
WScript.Echo "Update required: " & UpdateRequired


' Example output:
'Application ID: nsu=http://opcfoundation.org/UA/GDS/applications/ ;ns=2;g=aec94459-f513-4979-8619-8383555fca61
'Update required: False

Python

# Shows how to check if an application needs to update its certificate.
#
# Find all latest examples here: https://opclabs.doc-that.com/files/onlinedocs/OPCLabs-OpcStudio/Latest/examples.html .
# OPC client and subscriber examples in Python on GitHub: https://github.com/OPCLabs/Examples-QuickOPC-Python .
# 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.
# The QuickOPC package is needed. Install it using "pip install opclabs_quickopc".
import opclabs_quickopc

# Import .NET namespaces.
from OpcLabs.EasyOpc.UA import *
from OpcLabs.EasyOpc.UA.AddressSpace import *
from OpcLabs.EasyOpc.UA.Application import *
from OpcLabs.EasyOpc.UA.Extensions import *
from OpcLabs.EasyOpc.UA.Gds import *
from OpcLabs.EasyOpc.UA.OperationModel import *


# Define which GDS we will work with.
gdsEndpointDescriptor = UAEndpointDescriptor('opc.tcp://opcua.demo-this.com:58810/GlobalDiscoveryServer')
gdsEndpointDescriptor = UAEndpointDescriptorExtension.WithUserNameIdentity(gdsEndpointDescriptor,
                                                                           'appadmin', 'demo')

# Register our client application with the GDS, so that we obtain an application ID that we need later.
# Obtain the application interface.
application = EasyUAApplication.Instance
try:
    print('Registering to GDS...')
    applicationId = application.RegisterToGds(gdsEndpointDescriptor)
except UAException as uaException:
    print('*** Failure: ' + uaException.GetBaseException().Message)
    exit()
print('Application ID: ', applicationId, sep='')

# Instantiate the certificate management client object.
certificateManagementClient = EasyUACertificateManagementClient()

# Check if the application needs to update its certificate.
try:
    updateRequired = certificateManagementClient.GetCertificateStatus(gdsEndpointDescriptor,
                                                                      applicationId,
                                                                      UANodeId.Null,    # certificateGroupId
                                                                      UANodeId.Null)    # certificateTypeId
except UAException as uaException:
    print('*** Failure: ' + uaException.GetBaseException().Message)
    exit()

# Display results.
print('Update required: ', updateRequired, sep='')

print()
print('Finished.')

 

Example
// Shows how to find all registrations in the GDS.
//
// Find all latest examples here: https://opclabs.doc-that.com/files/onlinedocs/OPCLabs-OpcStudio/Latest/examples.html .
// OPC client and subscriber examples in C# on GitHub: https://github.com/OPCLabs/Examples-QuickOPC-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.Discovery;
using OpcLabs.EasyOpc.UA.Extensions;
using OpcLabs.EasyOpc.UA.Gds;
using OpcLabs.EasyOpc.UA.OperationModel;

namespace UADocExamples.Gds._EasyUAGlobalDiscoveryClient
{
    class FindApplications
    {
        public static void Main1()
        {
            // Define which GDS we will work with.
            UAEndpointDescriptor gdsEndpointDescriptor =
                ((UAEndpointDescriptor)"opc.tcp://opcua.demo-this.com:58810/GlobalDiscoveryServer")
                .WithUserNameIdentity("appuser", "demo");

            // Instantiate the global discovery client object
            var globalDiscoveryClient = new EasyUAGlobalDiscoveryClient();

            // Find all (client or server) applications registered in the GDS.
            UAApplicationDescription[] applicationDescriptionArray;
            try
            {
                globalDiscoveryClient.QueryApplications(
                    gdsEndpointDescriptor: gdsEndpointDescriptor,
                    startingRecordId: 0,
                    maximumRecordsToReturn: 0,
                    applicationName: "",
                    applicationUriString: "",
                    applicationTypes: UAApplicationTypes.All,
                    productUriString: "",
                    serverCapabilities: new string[0],
                    lastCounterResetTime: out _,
                    nextRecordId: out _,
                    applications: out applicationDescriptionArray);
            }
            catch (UAException uaException)
            {
                Console.WriteLine("*** Failure: {0}", uaException.GetBaseException().Message);
                return;
            }

            // For each application returned by the query, find its registrations in the GDS.
            foreach (UAApplicationDescription applicationDescription in applicationDescriptionArray)
            {
                Console.WriteLine();
                Console.WriteLine("Application URI string: {0}", applicationDescription.ApplicationUriString);

                UAApplicationRecordDataType[] applicationRecordArray;
                try
                {
                    applicationRecordArray = globalDiscoveryClient.FindApplications(
                        gdsEndpointDescriptor,
                        applicationDescription.ApplicationUriString);
                }
                catch (UAException uaException)
                {
                    Console.WriteLine("  *** Failure: {0}", uaException.GetBaseException().Message);
                    continue;
                }

                // Display results
                foreach (UAApplicationRecordDataType applicationRecord in applicationRecordArray)
                    Console.WriteLine("  Application ID: {0}", applicationRecord.ApplicationId);
            }


            // Example output:
            //
            //Application URI string: urn:sampleserver
            //  Application ID: nsu=http://opcfoundation.org/UA/GDS/applications/ ;ns=2;g=09ecaa08-6ec6-462c-a214-1e66a3099107
            //
            //Application URI string: urn:alarmconditionserver
            //  Application ID: nsu=http://opcfoundation.org/UA/GDS/applications/ ;ns=2;g=783e1e9a-8036-43b6-928f-97488c460266
            //
            //Application URI string: urn:PC:MultiTargetUADocExamples:5.54.1026.1:neutral:null
            //  Application ID: nsu=http://opcfoundation.org/UA/GDS/applications/ ;ns=2;g=9e700ea5-55a6-4c3c-ba9f-b91c890dc519
            //
            //Application URI string: urn:PC:UADocExamples:5.56.0.16:neutral:null
            //  Application ID: nsu=http://opcfoundation.org/UA/GDS/applications/ ;ns=2;g=e182e28c-086b-4fc7-82c7-70ca7cda3033
            //
            //Application URI string: urn:PC:cscript:5.812.10240.16384
            //  Application ID: nsu=http://opcfoundation.org/UA/GDS/applications/ ;ns=2;g=aec94459-f513-4979-8619-8383555fca61
        }
    }
}
' Shows how to find all registrations in the GDS.
'
' 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 OpcLabs.EasyOpc.UA
Imports OpcLabs.EasyOpc.UA.Discovery
Imports OpcLabs.EasyOpc.UA.Extensions
Imports OpcLabs.EasyOpc.UA.Gds
Imports OpcLabs.EasyOpc.UA.OperationModel

Namespace Gds._EasyUAGlobalDiscoveryClient
    Friend Class FindApplications
        Public Shared Sub Main1()

            ' Define which GDS we will work with.
            Dim gdsEndpointDescriptor As UAEndpointDescriptor =
                New UAEndpointDescriptor("opc.tcp://opcua.demo-this.com:58810/GlobalDiscoveryServer") _
                .WithUserNameIdentity("appuser", "demo")

            ' Instantiate the global discovery client object
            Dim globalDiscoveryClient = New EasyUAGlobalDiscoveryClient()

            ' Find all (client or server) applications registered in the GDS.
            Dim applicationDescriptionArray() As UAApplicationDescription = Nothing
            Try
                Dim lastCounterResetTime As DateTime
                Dim nextRecordId As Long
                globalDiscoveryClient.QueryApplications(
                    gdsEndpointDescriptor:=gdsEndpointDescriptor,
                    startingRecordId:=0,
                    maximumRecordsToReturn:=0,
                    applicationName:="",
                    applicationUriString:="",
                    applicationTypes:=UAApplicationTypes.All,
                    productUriString:="",
                    serverCapabilities:=New String() {},
                    lastCounterResetTime:=lastCounterResetTime,
                    nextRecordId:=nextRecordId,
                    applications:=applicationDescriptionArray)
            Catch uaException As UAException
                Console.WriteLine("*** Failure: {0}", uaException.GetBaseException.Message)
                Exit Sub
            End Try

            ' For each application returned by the query, find its registrations in the GDS.
            For Each applicationDescription As UAApplicationDescription In applicationDescriptionArray
                Console.WriteLine()
                Console.WriteLine("Application URI string: {0}", applicationDescription.ApplicationUriString)

                Dim applicationRecordArray() As UAApplicationRecordDataType
                Try
                    applicationRecordArray = globalDiscoveryClient.FindApplications(
                        gdsEndpointDescriptor,
                        applicationDescription.ApplicationUriString)
                Catch uaException As UAException
                    Console.WriteLine("*** Failure: {0}", uaException.GetBaseException.Message)
                    Continue For
                End Try

                ' Display results
                For Each applicationRecord As UAApplicationRecordDataType In applicationRecordArray
                    Console.WriteLine("  Application ID: {0}", applicationRecord.ApplicationId)
                Next applicationRecord
            Next applicationDescription
        End Sub
    End Class
End Namespace

// Shows how to find all registrations in the GDS.
//
// Find all latest examples here: https://opclabs.doc-that.com/files/onlinedocs/OPCLabs-OpcStudio/Latest/examples.html .
// OPC client and subscriber examples in Object Pascal (Delphi) on GitHub: https://github.com/OPCLabs/Examples-QuickOPC-OP .
// 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.

class procedure FindApplications.Main;
var
  ApplicationDescription: _UAApplicationDescription;
  ApplicationDescriptionArray: OleVariant;
  ApplicationName: WideString;
  ApplicationRecord: _UAApplicationRecordDataType;
  ApplicationRecordArray: OleVariant;
  ApplicationUriString: WideString;
  GlobalDiscoveryClient: OpcLabs_EasyOpcUA_TLB._EasyUAGlobalDiscoveryClient;
  GdsEndpointDescriptor: _UAEndpointDescriptor;
  I, J: integer;
  LastCounterResetTime: TDateTime;
  MaximumRecordsToReturn: Integer;
  NextRecordId: Integer;
  ProductUriString: WideString;
  ServerCapabilities: array of string;
  StartingRecordId: Integer;
begin
  // Define which GDS we will work with.
  GdsEndpointDescriptor := CoUAEndpointDescriptor.Create;
  GdsEndpointDescriptor.UrlString := 'opc.tcp://opcua.demo-this.com:58810/GlobalDiscoveryServer';
  GdsEndpointDescriptor.UserIdentity.UserNameTokenInfo.UserName := 'appadmin';
  GdsEndpointDescriptor.UserIdentity.UserNameTokenInfo.Password := 'demo';

  // Instantiate the global discovery client object
  GlobalDiscoveryClient := CoEasyUAGlobalDiscoveryClient.Create;

  // Find all (client or server) applications registered in the GDS.
  StartingRecordId := 0;
  MaximumRecordsToReturn := 0;
  ApplicationName := '';
  ApplicationUriString := '';
  ProductUriString := '';
  try
    GlobalDiscoveryClient.QueryApplications(
      GdsEndpointDescriptor,
      StartingRecordId,
      MaximumRecordsToReturn,
      ApplicationName,
      ApplicationUriString,
      UAApplicationTypes_All,
      ProductUriString,
      ServerCapabilities,
      LastCounterResetTime,
      NextRecordId,
      ApplicationDescriptionArray);
  except
    on E: EOleException do
    begin
      WriteLn(Format('*** Failure: %s', [E.GetBaseException.Message]));
    end;
  end;

  // For each application returned by the query, find its registrations in the GDS.
  for I := VarArrayLowBound(ApplicationDescriptionArray,1) to VarArrayHighBound(ApplicationDescriptionArray,1) do
  begin
    ApplicationDescription := IUnknown(ApplicationDescriptionArray[I]) as _UAApplicationDescription;
    WriteLn;
    WriteLn('Application URI string: ', ApplicationDescription.ApplicationUriString);
    try
    TVarData(ApplicationRecordArray).VType := varArray or varVariant;
    TVarData(ApplicationRecordArray).VArray := PVarArray(
      GlobalDiscoveryClient.FindApplications(
        GdsEndpointDescriptor,
        ApplicationDescription.ApplicationUriString));
    except
      on E: EOleException do
      begin
        WriteLn(Format('*** Failure: %s', [E.GetBaseException.Message]));
        Continue;
      end;
    end;
      for J := VarArrayLowBound(ApplicationRecordArray, 1) to VarArrayHighBound(ApplicationRecordArray, 1) do
      begin
        // Display results
        ApplicationRecord := IUnknown(ApplicationRecordArray[J]) as _UAApplicationRecordDataType;
        WriteLn('  Application ID: ', ApplicationRecord.ApplicationId.ToString);
      end;
  end;

  // Example output:
  //
  //Application URI string: urn:sampleserver
  //  Application ID: nsu=http://opcfoundation.org/UA/GDS/applications/ ;ns=2;g=09ecaa08-6ec6-462c-a214-1e66a3099107
  //
  //Application URI string: urn:alarmconditionserver
  //  Application ID: nsu=http://opcfoundation.org/UA/GDS/applications/ ;ns=2;g=783e1e9a-8036-43b6-928f-97488c460266
  //
  //Application URI string: urn:PC:MultiTargetUADocExamples:5.54.1026.1:neutral:null
  //  Application ID: nsu=http://opcfoundation.org/UA/GDS/applications/ ;ns=2;g=9e700ea5-55a6-4c3c-ba9f-b91c890dc519
  //
  //Application URI string: urn:PC:UADocExamples:5.56.0.16:neutral:null
  //  Application ID: nsu=http://opcfoundation.org/UA/GDS/applications/ ;ns=2;g=e182e28c-086b-4fc7-82c7-70ca7cda3033
  //
  //Application URI string: urn:PC:cscript:5.812.10240.16384
  //  Application ID: nsu=http://opcfoundation.org/UA/GDS/applications/ ;ns=2;g=aec94459-f513-4979-8619-8383555fca61

end;
Rem Shows how to find all registrations in the GDS.
Rem
Rem Find all latest examples here: https://opclabs.doc-that.com/files/onlinedocs/OPCLabs-OpcStudio/Latest/examples.html .
Rem OPC client and subscriber examples in VBScript on GitHub: https://github.com/OPCLabs/Examples-QuickOPC-VBScript .
Rem Missing some example? Ask us for it on our Online Forums, https://www.opclabs.com/forum/index ! You do not have to own
Rem a commercial license in order to use Online Forums, and we reply to every post.

Option Explicit

Const UAApplicationTypes_All = 7

' Define which GDS we will work with.
Dim GdsEndpointDescriptor: Set GdsEndpointDescriptor = CreateObject("OpcLabs.EasyOpc.UA.UAEndpointDescriptor")
GdsEndpointDescriptor.UrlString = "opc.tcp://opcua.demo-this.com:58810/GlobalDiscoveryServer"
GdsEndpointDescriptor.UserIdentity.UserNameTokenInfo.UserName = "appadmin"
GdsEndpointDescriptor.UserIdentity.UserNameTokenInfo.Password = "demo"

' Instantiate the global discovery client object
Dim GlobalDiscoveryClient: Set GlobalDiscoveryClient = CreateObject("OpcLabs.EasyOpc.UA.Gds.EasyUAGlobalDiscoveryClient")

' Find all (client or server) applications registered in the GDS.
Dim startingRecordId: startingRecordId = 0
Dim maximumRecordsToReturn: maximumRecordsToReturn = 0
Dim applicationName: applicationName = ""
Dim applicationUriString: applicationUriString = ""
Dim productUriString: productUriString = ""
Dim serverCapabilities: serverCapabilities = Array()
Dim lastCounterResetTime
Dim nextRecordId
Dim applicationDescriptionArray
On Error Resume Next
GlobalDiscoveryClient.QueryApplications _
    GdsEndpointDescriptor, _
    startingRecordId, _
    maximumRecordsToReturn, _
    applicationName, _
    applicationUriString, _
    UAApplicationTypes_All, _
    productUriString, _
    serverCapabilities, _ 
    lastCounterResetTime, _
    nextRecordId, _
    applicationDescriptionArray
If Err.Number <> 0 Then
    WScript.Echo "*** Failure: " & Err.Source & ": " & Err.Description
    WScript.Quit
End If
On Error Goto 0

' For each application returned by the query, find its registrations in the GDS.
Dim ApplicationDescription
For Each ApplicationDescription In applicationDescriptionArray
    WScript.Echo
    WScript.Echo "Application URI string: " & ApplicationDescription.ApplicationUriString

    On Error Resume Next
    Dim applicationRecordArray: applicationRecordArray = GlobalDiscoveryClient.FindApplications( _
        gdsEndpointDescriptor, _
        ApplicationDescription.ApplicationUriString)
    If Err.Number <> 0 Then
        WScript.Echo "  *** Failure: " & Err.Source & ": " & Err.Description
    Else
        Dim ApplicationRecord
        For Each ApplicationRecord In applicationRecordArray
            ' Display results
            WScript.Echo "  Application ID: " & ApplicationRecord.ApplicationId
        Next
    End If
    On Error Goto 0
Next


' Example output:
'
'Application URI string: urn:sampleserver
'  Application ID: nsu=http://opcfoundation.org/UA/GDS/applications/ ;ns=2;g=09ecaa08-6ec6-462c-a214-1e66a3099107
'
'Application URI string: urn:alarmconditionserver
'  Application ID: nsu=http://opcfoundation.org/UA/GDS/applications/ ;ns=2;g=783e1e9a-8036-43b6-928f-97488c460266
'
'Application URI string: urn:PC:MultiTargetUADocExamples:5.54.1026.1:neutral:null
'  Application ID: nsu=http://opcfoundation.org/UA/GDS/applications/ ;ns=2;g=9e700ea5-55a6-4c3c-ba9f-b91c890dc519
'
'Application URI string: urn:PC:UADocExamples:5.56.0.16:neutral:null
'  Application ID: nsu=http://opcfoundation.org/UA/GDS/applications/ ;ns=2;g=e182e28c-086b-4fc7-82c7-70ca7cda3033
'
'Application URI string: urn:PC:cscript:5.812.10240.16384
'  Application ID: nsu=http://opcfoundation.org/UA/GDS/applications/ ;ns=2;g=aec94459-f513-4979-8619-8383555fca61

# Shows how to find all registrations in the GDS.
#
# Find all latest examples here: https://opclabs.doc-that.com/files/onlinedocs/OPCLabs-OpcStudio/Latest/examples.html .
# OPC client and subscriber examples in Python on GitHub: https://github.com/OPCLabs/Examples-QuickOPC-Python .
# 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.
# The QuickOPC package is needed. Install it using "pip install opclabs_quickopc".
import opclabs_quickopc

# Import .NET namespaces.
from System import *
from OpcLabs.EasyOpc.UA import *
from OpcLabs.EasyOpc.UA.Discovery import *
from OpcLabs.EasyOpc.UA.Extensions import *
from OpcLabs.EasyOpc.UA.Gds import *
from OpcLabs.EasyOpc.UA.OperationModel import *


# Define which GDS we will work with.
gdsEndpointDescriptor = UAEndpointDescriptor('opc.tcp://opcua.demo-this.com:58810/GlobalDiscoveryServer')
gdsEndpointDescriptor = UAEndpointDescriptorExtension.WithUserNameIdentity(gdsEndpointDescriptor,
                                                                           'appadmin', 'demo')

# Instantiate the global discovery client object.
globalDiscoveryClient = EasyUAGlobalDiscoveryClient()

# Find all (client or server) applications registered in the GDS.
try:
    _, _, _, applicationDescriptionArray = globalDiscoveryClient.QueryApplications(
        gdsEndpointDescriptor,
        0,  # startingRecordId
        0,  # maximumRecordsToReturn
        '', # applicationName
        '', # applicationUriString
        UAApplicationTypes.All, # applicationTypes
        '', # productUriString
        Array.Empty[String](),  # serverCapabilities
        DateTime(), # out lastCounterResetTime
        0,  # out nextRecordId
        Array.Empty[UAApplicationDescription]()) # out applications
except UAException as uaException:
    print('*** Failure: ' + uaException.GetBaseException().Message)
    exit()

# For each application returned by the query, find its registrations in the GDS.
for applicationDescription in applicationDescriptionArray:
    print()
    print('Application URI string: ', applicationDescription.ApplicationUriString, sep='')

    try:
        applicationRecordArray = globalDiscoveryClient.FindApplications(
            gdsEndpointDescriptor,
            applicationDescription.ApplicationUriString)
    except UAException as uaException:
        print('  *** Failure: ' + uaException.GetBaseException().Message)
        continue

    # Display results.
    for applicationRecord in applicationRecordArray:
        print('  Application ID: ', applicationRecord.ApplicationId, sep='')

print()
print('Finished.')
Requirements

Target Platforms: .NET Framework: Windows 10 (selected versions), Windows 11 (selected versions), Windows Server 2016, Windows Server 2022; .NET: Linux, macOS, Microsoft Windows

See Also

Reference

IEasyUAGlobalDiscoveryClient Members
OpcLabs.EasyOpc.UA.Gds Namespace

 

 

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