Globally discovers OPC-UA servers and returns information about them, using an empty filter, and the default GDS endpoint.
Syntax
Return Value
Returns a collection of application elements (usually servers,
OpcLabs.EasyOpc.UA.Discovery.UADiscoveryElement).
This method never returns null
(Nothing
in Visual Basic).
The individual elements of the returned value are never null
(Nothing
in Visual Basic).
Exceptions
Example
// This example shows how to obtain information about OPC UA servers from the Global Discovery Server (GDS).
// The result is flat, i.e. each discovery URL is returned in separate element, with possible repetition of the servers.
//
// 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.OperationModel;
namespace UADocExamples._EasyUAClient
{
partial class DiscoverGlobalServers
{
public static void Main1()
{
// Instantiate the client object.
var client = new EasyUAClient();
// Obtain collection of application elements.
UADiscoveryElementCollection discoveryElementCollection;
try
{
discoveryElementCollection = client.DiscoverGlobalServers(
"opc.tcp://opcua.demo-this.com:58810/GlobalDiscoveryServer");
}
catch (UAException uaException)
{
Console.WriteLine($"*** Failure: {uaException.GetBaseException().Message}");
return;
}
// Display results.
foreach (UADiscoveryElement discoveryElement in discoveryElementCollection)
{
Console.WriteLine();
Console.WriteLine($"Server name: {discoveryElement.ServerName}");
Console.WriteLine($"Discovery URI string: {discoveryElement.DiscoveryUriString}");
Console.WriteLine($"Server capabilities: {discoveryElement.ServerCapabilities}");
}
}
}
}
# This example shows how to obtain information about OPC UA servers from the Global Discovery Server (GDS).
# The result is flat, i.e. each discovery URL is returned in separate element, with possible repetition of the servers.
#
# Find all latest examples here: https://opclabs.doc-that.com/files/onlinedocs/OPCLabs-OpcStudio/Latest/examples.html .
# OPC client and subscriber examples in PowerShell on GitHub: https://github.com/OPCLabs/Examples-QuickOPC-PowerShell .
# 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.
#requires -Version 5.1
using namespace OpcLabs.EasyOpc.UA
using namespace OpcLabs.EasyOpc.UA.Discovery
using namespace OpcLabs.EasyOpc.UA.OperationModel
# The path below assumes that the current directory is [ProductDir]/Examples-NET/PowerShell/Windows .
Add-Type -Path "../../../Components/Opclabs.QuickOpc/net472/OpcLabs.EasyOpcUA.dll"
Add-Type -Path "../../../Components/Opclabs.QuickOpc/net472/OpcLabs.EasyOpcUAComponents.dll"
# Instantiate the client object.
$client = New-Object EasyUAClient
# Obtain collection of application elements.
try {
$discoveryElementCollection = [IEasyUAClientExtension]::DiscoverGlobalServers($client,
"opc.tcp://opcua.demo-this.com:58810/GlobalDiscoveryServer")
}
catch [UAException] {
Write-Host "*** Failure: $($PSItem.Exception.GetBaseException().Message)"
return
}
# Display results.
foreach ($discoveryElement in $discoveryElementCollection) {
Write-Host
Write-Host "Server name: $($discoveryElement.ServerName)"
Write-Host "Discovery URI string: $($discoveryElement.DiscoveryUriString)"
Write-Host "Server capabilities: $($discoveryElement.ServerCapabilities)"
}
# Example output:
#
' This example shows how to obtain information about OPC UA servers from the Global Discovery Server (GDS).
' The result is flat, i.e. each discovery URL is returned in separate element, with possible repetition of the servers.
'
' 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.OperationModel
Namespace _EasyUAClient
Partial Friend Class DiscoverGlobalServers
Public Shared Sub Main1()
' Instantiate the client object
Dim client = New EasyUAClient()
' Obtain collection of application elements
Dim discoveryElementCollection As UADiscoveryElementCollection
Try
discoveryElementCollection = client.DiscoverGlobalServers("opc.tcp://opcua.demo-this.com:58810/GlobalDiscoveryServer")
Catch uaException As UAException
Console.WriteLine("*** Failure: {0}", uaException.GetBaseException.Message)
Exit Sub
End Try
' Display results
For Each discoveryElement As UADiscoveryElement In discoveryElementCollection
Console.WriteLine()
Console.WriteLine("Server name: {0}", discoveryElement.ServerName)
Console.WriteLine("Discovery URI string: {0}", discoveryElement.DiscoveryUriString)
Console.WriteLine("Server capabilities: {0}", discoveryElement.ServerCapabilities)
Next discoveryElement
End Sub
End Class
End Namespace
// This example shows how to obtain information about OPC UA servers from the Global Discovery Server (GDS).
// The result is flat, i.e. each discovery URL is returned in separate element, with possible repetition of the servers.
//
// 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 DiscoverGlobalServers.Main;
var
Client: OpcLabs_EasyOpcUA_TLB._EasyUAClient;
Count: Cardinal;
Element: OleVariant;
DiscoveryElement: _UADiscoveryElement;
DiscoveryElementEnumerator: IEnumVariant;
DiscoveryElements: _UADiscoveryElementCollection;
begin
// Instantiate the client object
Client := CoEasyUAClient.Create;
// Obtain collection of application elements
try
DiscoveryElements := Client.DiscoverGlobalServers('opc.tcp://opcua.demo-this.com:58810/GlobalDiscoveryServer');
except
on E: EOleException do
begin
WriteLn(Format('*** Failure: %s', [E.GetBaseException.Message]));
Exit;
end;
end;
// Display results
DiscoveryElementEnumerator := DiscoveryElements.GetEnumerator;
while (DiscoveryElementEnumerator.Next(1, Element, Count) = S_OK) do
begin
DiscoveryElement := IUnknown(Element) as _UADiscoveryElement;
WriteLn;
WriteLn('Server name: ', DiscoveryElement.ServerName);
WriteLn('Discovery URI string: ', DiscoveryElement.DiscoveryUriString);
WriteLn('Server capabilities: ', DiscoveryElement.ServerCapabilities.ToString);
end;
end;
REM This example shows how to obtain information about OPC UA servers from the Global Discovery Server (GDS).
REM The result is flat, i.e. each discovery URL is returned in separate element, with possible repetition of the servers.
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.
Public Sub DiscoverGlobalServers_Main_Command_Click()
OutputText = ""
' Instantiate the client object
Dim Client As New EasyUAClient
' Obtain collection of application elements
On Error Resume Next
Dim DiscoveryElementCollection As UADiscoveryElementCollection
Set DiscoveryElementCollection = Client.DiscoverGlobalServers("opc.tcp://opcua.demo-this.com:58810/GlobalDiscoveryServer")
If Err.Number <> 0 Then
OutputText = OutputText & "*** Failure: " & Err.Source & ": " & Err.Description & vbCrLf
Exit Sub
End If
On Error GoTo 0
' Display results
Dim DiscoveryElement As UADiscoveryElement: For Each DiscoveryElement In DiscoveryElementCollection
OutputText = OutputText & vbCrLf
OutputText = OutputText & "Server name: " & DiscoveryElement.ServerName & vbCrLf
OutputText = OutputText & "Discovery URI string: " & DiscoveryElement.DiscoveryUriString & vbCrLf
OutputText = OutputText & "Server capabilities: " & DiscoveryElement.serverCapabilities.ToString & vbCrLf
Next
End Sub
# This example shows how to obtain information about OPC UA servers from the Global Discovery Server (GDS).
# The result is flat, i.e. each discovery URL is returned in separate element, with possible repetition of the servers.
#
# 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.Discovery import *
from OpcLabs.EasyOpc.UA.OperationModel import *
# Instantiate the client object.
client = EasyUAClient()
# Obtain collection of application elements.
try:
discoveryElementCollection = IEasyUAClientExtension.DiscoverGlobalServers(client,
UAEndpointDescriptor('opc.tcp://opcua.demo-this.com:58810/GlobalDiscoveryServer'))
except UAException as uaException:
print('*** Failure: ' + uaException.GetBaseException().Message)
exit()
# Display results.
for discoveryElement in discoveryElementCollection:
print()
print('Server name: ', discoveryElement.ServerName, sep='')
print('Discovery URI string: ', discoveryElement.DiscoveryUriString, sep='')
print('Server capabilities: ', discoveryElement.ServerCapabilities, sep='')
print()
print('Finished.')
// This example shows how to obtain information about OPC UA servers from the Global Discovery Server (GDS).
// The result is hierarchical, i.e. each server is returned in one element, and the element contains all its discovery URLs.
//
// 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.OperationModel;
namespace UADocExamples._EasyUAClient
{
partial class DiscoverGlobalServers
{
public static void Hierarchical()
{
// Instantiate the client object
var client = new EasyUAClient();
// Obtain collection of application elements
UADiscoveryElementCollection discoveryElementCollection;
try
{
discoveryElementCollection = client.DiscoverGlobalServers(
"opc.tcp://opcua.demo-this.com:58810/GlobalDiscoveryServer",
flat:false);
}
catch (UAException uaException)
{
Console.WriteLine("*** Failure: {0}", uaException.GetBaseException().Message);
return;
}
// Display results
foreach (UADiscoveryElement discoveryElement in discoveryElementCollection)
{
Console.WriteLine();
Console.WriteLine("Server name: {0}", discoveryElement.ServerName);
Console.WriteLine("Discovery URI strings:");
foreach (string discoveryUriString in discoveryElement.DiscoveryUriStrings)
Console.WriteLine(" {0}", discoveryUriString);
Console.WriteLine("Server capabilities: {0}", discoveryElement.ServerCapabilities);
Console.WriteLine("Application URI string: {0}", discoveryElement.ApplicationUriString);
Console.WriteLine("Product URI string: {0}", discoveryElement.ProductUriString);
}
}
}
}
' This example shows how to obtain information about OPC UA servers from the Global Discovery Server (GDS).
' The result is hierarchical, i.e. each server is returned in one element, and the element contains all its discovery URLs.
'
' 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.OperationModel
Namespace _EasyUAClient
Partial Friend Class DiscoverGlobalServers
Public Shared Sub Hierarchical()
' Instantiate the client object
Dim client = New EasyUAClient()
' Obtain collection of application elements
Dim discoveryElementCollection As UADiscoveryElementCollection
Try
discoveryElementCollection = client.DiscoverGlobalServers( _
"opc.tcp://opcua.demo-this.com:58810/GlobalDiscoveryServer",
flat:=False)
Catch uaException As UAException
Console.WriteLine("*** Failure: {0}", uaException.GetBaseException.Message)
Exit Sub
End Try
' Display results
For Each discoveryElement As UADiscoveryElement In discoveryElementCollection
Console.WriteLine()
Console.WriteLine("Server name: {0}", discoveryElement.ServerName)
Console.WriteLine("Discovery URI strings:")
For Each discoveryUriString As String In discoveryElement.DiscoveryUriStrings
Console.WriteLine(" {0}", discoveryUriString)
Next discoveryUriString
Console.WriteLine("Server capabilities: {0}", discoveryElement.ServerCapabilities)
Console.WriteLine("Application URI string: {0}", discoveryElement.ApplicationUriString)
Console.WriteLine("Product URI string: {0}", discoveryElement.ProductUriString)
Next discoveryElement
End Sub
End Class
End Namespace
# This example shows how to obtain information about OPC UA servers from the Global Discovery Server (GDS).
# The result is hierarchical, i.e. each server is returned in one element, and the element contains all its discovery
# URLs.
#
# 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.Discovery import *
from OpcLabs.EasyOpc.UA.OperationModel import *
# Instantiate the client object.
client = EasyUAClient()
# Obtain collection of application elements.
try:
discoveryElementCollection = IEasyUAClientExtension.DiscoverGlobalServers(client,
UAEndpointDescriptor('opc.tcp://opcua.demo-this.com:58810/GlobalDiscoveryServer'),
False) # flat=False
except UAException as uaException:
print('*** Failure: ' + uaException.GetBaseException().Message)
exit()
# Display results.
for discoveryElement in discoveryElementCollection:
print()
print('Server name: ', discoveryElement.ServerName, sep='')
print('Discovery URI strings:')
for discoveryUriString in discoveryElement.DiscoveryUriStrings:
print(' ', discoveryUriString, sep='')
print('Server capabilities: ', discoveryElement.ServerCapabilities, sep='')
print('Application URI string: ', discoveryElement.ApplicationUriString, sep='')
print('Product URI string: ', discoveryElement.ProductUriString, 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