Examples - OPC UA GDS and CM - Query for applications

.NET

C#
VB.NET

// Shows how to find client or server applications that meet the specified filters, using the global discovery client.
//
// 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.Discovery;
using OpcLabs.EasyOpc.UA.Gds;
using OpcLabs.EasyOpc.UA.OperationModel;

namespace UADocExamples.Gds._EasyUAGlobalDiscoveryClient
{
    class QueryApplications
    {
        public static void Main1()
        {
            // 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:"opc.tcp://opcua.demo-this.com:58810/GlobalDiscoveryServer",
                    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;
            }

            // Display results
            foreach (UAApplicationDescription applicationDescription in applicationDescriptionArray)
            {
                Console.WriteLine();
                Console.WriteLine("Application name: {0}", applicationDescription.ApplicationName);
                Console.WriteLine("Application type: {0}", applicationDescription.ApplicationType);
                Console.WriteLine("Application URI string: {0}", applicationDescription.ApplicationUriString);
                Console.WriteLine("Discovery URI strings: {0}", applicationDescription.DiscoveryUriStrings);
            }
        }
    }
}

' Shows how to find client or server applications that meet the specified filters, using the global discovery client.
'
' 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.Discovery
Imports OpcLabs.EasyOpc.UA.Gds
Imports OpcLabs.EasyOpc.UA.OperationModel

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

            ' 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:="opc.tcp://opcua.demo-this.com:58810/GlobalDiscoveryServer",
                    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

            ' Display results
            For Each applicationDescription As UAApplicationDescription In applicationDescriptionArray
                Console.WriteLine()
                Console.WriteLine("Application name: {0}", applicationDescription.ApplicationName)
                Console.WriteLine("Application type: {0}", applicationDescription.ApplicationType)
                Console.WriteLine("Application URI string: {0}", applicationDescription.ApplicationUriString)
                Console.WriteLine("Discovery URI strings: {0}", applicationDescription.DiscoveryUriStrings)
            Next applicationDescription
        End Sub
    End Class
End Namespace

COM

Object Pascal
Visual Basic (VB 6.)

// Shows how to find client or server applications that meet the specified filters, using the global discovery client.
//
// 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 QueryApplications.Main;
var
  ApplicationDescription: _UAApplicationDescription;
  ApplicationDescriptionArray: OleVariant;
  ApplicationName: WideString;
  ApplicationUriString: WideString;
  GlobalDiscoveryClient: OpcLabs_EasyOpcUA_TLB._EasyUAGlobalDiscoveryClient;
  GdsEndpointDescriptor: _UAEndpointDescriptor;
  I: 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';

  // 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;

  // Display results
  for I := VarArrayLowBound(ApplicationDescriptionArray,1) to VarArrayHighBound(ApplicationDescriptionArray,1) do
  begin
    ApplicationDescription := IUnknown(ApplicationDescriptionArray[I]) as _UAApplicationDescription;
    WriteLn;
    WriteLn('Application name: ', ApplicationDescription.ApplicationName);
    WriteLn('Application type: ', ApplicationDescription.ApplicationType);
    WriteLn('Application URI string: ', ApplicationDescription.ApplicationUriString);
    WriteLn('Discovery URI strings: ', ApplicationDescription.DiscoveryUriStrings.ToString);
  end;

end;

REM Shows how to find client or server applications that meet the specified filters, using the global discovery client.
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 EasyUAGlobalDiscoveryClient_QueryApplications_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"
    
    ' Instantiate the global discovery client object
    Dim globalDiscoveryClient As New EasyUAGlobalDiscoveryClient
    
    ' Find all (client or server) applications registered in the GDS.
    Dim startingRecordId As Long: startingRecordId = 0
    Dim maximumRecordsToReturn As Long: maximumRecordsToReturn = 0
    Dim applicationName As String: applicationName = ""
    Dim applicationUriString As String: applicationUriString = ""
    Dim productUriString As String: productUriString = ""
    Dim serverCapabilities: serverCapabilities = Array()
    Dim lastCounterResetTime As Date
    Dim nextRecordId As Long
    Dim applicationDescriptionArray As Variant
    On Error Resume Next
    Dim applicationId As UANodeId
    Call globalDiscoveryClient.QueryApplications( _
      gdsEndpointDescriptor, _
      startingRecordId, _
      maximumRecordsToReturn, _
      applicationName, _
      applicationUriString, _
      UAApplicationTypes_All, _
      productUriString, _
      serverCapabilities, _
      lastCounterResetTime, _
      nextRecordId, _
      applicationDescriptionArray)
    If Err.Number <> 0 Then
        OutputText = OutputText & "*** Failure: " & Err.Source & ": " & Err.Description & vbCrLf
        Exit Sub
    End If
    On Error GoTo 0
    
    ' Display results
    Dim i: For i = LBound(applicationDescriptionArray) To UBound(applicationDescriptionArray)
        Dim applicationDescription As UAApplicationDescription
        Set applicationDescription = applicationDescriptionArray(i)
        OutputText = OutputText & vbCrLf
        OutputText = OutputText & "Application name: " & applicationDescription.applicationName & vbCrLf
        OutputText = OutputText & "Application type: " & applicationDescription.ApplicationType & vbCrLf
        OutputText = OutputText & "Application URI string: " & applicationDescription.applicationUriString & vbCrLf
        OutputText = OutputText & "Discovery URI strings: " & applicationDescription.DiscoveryUriStrings.ToString & vbCrLf
    Next
End Sub

Python

Python (.NET)

# 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.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')

# 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()

# Display results.
for applicationDescription in applicationDescriptionArray:
    print()
    print('Application name: ', applicationDescription.ApplicationName, sep='')
    print('Application type: ', applicationDescription.ApplicationType, sep='')
    print('Application URI string: ', applicationDescription.ApplicationUriString, sep='')
    print('Discovery URI strings: ', applicationDescription.DiscoveryUriStrings, sep='')

print()
print('Finished.')

Concepts

OPC UA Global Discovery Client