OPC Studio User's Guide and Reference
BrowseDataNodes(IEasyUAClient,UAEndpointDescriptor) Method
Example 



OpcLabs.EasyOpcUA Assembly > OpcLabs.EasyOpc.UA Namespace > IEasyUAClientExtension Class > BrowseDataNodes Method : BrowseDataNodes(IEasyUAClient,UAEndpointDescriptor) Method
The client object that will perform the operation.
Endpoint descriptor. Identifies the OPC-UA server.
Browses the data nodes in OPC server's address space. Starts from the specified node (or Objects folder), and returns information about child nodes found. Browses the data nodes, specifying an endpoint descriptor, and starting from the Objects folder.
Syntax
'Declaration
 
<ExtensionAttribute()>
<ElementsNotNullAttribute()>
<NotNullAttribute()>
Public Overloads Shared Function BrowseDataNodes( _
   ByVal client As IEasyUAClient, _
   ByVal endpointDescriptor As UAEndpointDescriptor _
) As UANodeElementCollection
'Usage
 
Dim client As IEasyUAClient
Dim endpointDescriptor As UAEndpointDescriptor
Dim value As UANodeElementCollection
 
value = IEasyUAClientExtension.BrowseDataNodes(client, endpointDescriptor)
[Extension()]
[ElementsNotNull()]
[NotNull()]
public static UANodeElementCollection BrowseDataNodes( 
   IEasyUAClient client,
   UAEndpointDescriptor endpointDescriptor
)
[Extension()]
[ElementsNotNull()]
[NotNull()]
public:
static UANodeElementCollection^ BrowseDataNodes( 
   IEasyUAClient^ client,
   UAEndpointDescriptor^ endpointDescriptor
) 

Parameters

client
The client object that will perform the operation.
endpointDescriptor
Endpoint descriptor. Identifies the OPC-UA server.

Return Value

The method returns a node element collection, which contains OpcLabs.EasyOpc.UA.AddressSpace.UANodeElement values. Each element contains information about a particular node found.
Exceptions
ExceptionDescription

A null reference (Nothing in Visual Basic) is passed to a method that does not accept it as a valid argument.

This is a usage error, i.e. it will never occur (the exception will not be thrown) in a correctly written program. Your code should not catch this exception.

The OPC UA operation has failed. This operation exception in uniformly used to allow common handling of various kinds of errors. The System.Exception.InnerException always contains information about the actual error cause.

This is an operation error that depends on factors external to your program, and thus cannot be always avoided. Your code must handle it appropriately.

Remarks

This overload starts the browsing from the Objects folder.

Data nodes are Objects and Variables (Variables are Data Variables and Properties).

Example

.NET

.NET

// This example shows how to obtain "data nodes" (objects, variables and properties) under the "Objects" node in the address
// space.
//
// Find all latest examples here: https://opclabs.doc-that.com/files/onlinedocs/OPCLabs-OpcStudio/Latest/examples.html .

using System;
using OpcLabs.EasyOpc.UA;
using OpcLabs.EasyOpc.UA.AddressSpace;
using OpcLabs.EasyOpc.UA.OperationModel;

namespace UADocExamples._EasyUAClient
{
    partial class BrowseDataNodes
    {
        public static void Overload1()
        {
            UAEndpointDescriptor endpointDescriptor =
                "opc.tcp://opcua.demo-this.com:51210/UA/SampleServer";
            // or "http://opcua.demo-this.com:51211/UA/SampleServer" (currently not supported)
            // or "https://opcua.demo-this.com:51212/UA/SampleServer/"

            // Instantiate the client object
            var client = new EasyUAClient();

            // Obtain data nodes under "Objects" node.
            UANodeElementCollection nodeElementCollection;
            try
            {
                nodeElementCollection = client.BrowseDataNodes(endpointDescriptor);
            }
            catch (UAException uaException)
            {
                Console.WriteLine($"*** Failure: {uaException.GetBaseException().Message}");
                return;
            }

            // Display results
            foreach (UANodeElement nodeElement in nodeElementCollection)
            {
                Console.WriteLine();
                Console.WriteLine($"nodeElement.DisplayName: {nodeElement.DisplayName}");
                Console.WriteLine($"nodeElement.NodeId: {nodeElement.NodeId}");
                Console.WriteLine($"nodeElement.NodeId.ExpandedText: {nodeElement.NodeId.ExpandedText}");
            }
        }

        // Example output:
        //
        //nodeElement.DisplayName: Server
        //nodeElement.NodeId: Server
        //nodeElement.NodeId.ExpandedText: nsu = http://opcfoundation.org/UA/ ;i=2253
        //
        //nodeElement.DisplayName: Data
        //nodeElement.NodeId: nsu = http://test.org/UA/Data/ ;ns=2;i=10157
        //nodeElement.NodeId.ExpandedText: nsu = http://test.org/UA/Data/ ;ns=2;i=10157
        //
        //nodeElement.DisplayName: Boilers
        //nodeElement.NodeId: nsu = http://opcfoundation.org/UA/Boiler/ ;ns=4;i=1240
        //nodeElement.NodeId.ExpandedText: nsu = http://opcfoundation.org/UA/Boiler/ ;ns=4;i=1240
        //
        //nodeElement.DisplayName: MemoryBuffers
        //nodeElement.NodeId: nsu = http://samples.org/UA/memorybuffer ;ns=7;i=1025
        //nodeElement.NodeId.ExpandedText: nsu = http://samples.org/UA/memorybuffer ;ns=7;i=1025
    }
}
# This example shows how to obtain "data nodes" (objects, variables and properties) under the "Objects" node in the address
# space.
#
# Find all latest examples here: https://opclabs.doc-that.com/files/onlinedocs/OPCLabs-OpcStudio/Latest/examples.html .

#requires -Version 5.1
using namespace OpcLabs.EasyOpc.UA
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"

[UAEndpointDescriptor]$endpointDescriptor =
    "opc.tcp://opcua.demo-this.com:51210/UA/SampleServer"
# or "http://opcua.demo-this.com:51211/UA/SampleServer" (currently not supported)
# or "https://opcua.demo-this.com:51212/UA/SampleServer/"

# Instantiate the client object.
$client = New-Object EasyUAClient

# Obtain data nodes under "Objects" node.
try {
    $nodeElementCollection = [IEasyUAClientExtension]::BrowseDataNodes($client, $endpointDescriptor)
}
catch [UAException] {
    Write-Host "*** Failure: $($PSItem.Exception.GetBaseException().Message)"
    return
}

# Display results
foreach ($nodeElement in $nodeElementCollection) {
    Write-Host
    Write-Host "nodeElement.DisplayName: $($nodeElement.DisplayName)"
    Write-Host "nodeElement.NodeId: $($nodeElement.NodeId)"
    Write-Host "nodeElement.NodeId.ExpandedText: $($nodeElement.NodeId.ExpandedText)"
}


# Example output:
#
#nodeElement.DisplayName: Server
#nodeElement.NodeId: Server
#nodeElement.NodeId.ExpandedText: nsu = http://opcfoundation.org/UA/ ;i=2253
#
#nodeElement.DisplayName: Data
#nodeElement.NodeId: nsu = http://test.org/UA/Data/ ;ns=2;i=10157
#nodeElement.NodeId.ExpandedText: nsu = http://test.org/UA/Data/ ;ns=2;i=10157
#
#nodeElement.DisplayName: Boilers
#nodeElement.NodeId: nsu = http://opcfoundation.org/UA/Boiler/ ;ns=4;i=1240
#nodeElement.NodeId.ExpandedText: nsu = http://opcfoundation.org/UA/Boiler/ ;ns=4;i=1240
#
#nodeElement.DisplayName: MemoryBuffers
#nodeElement.NodeId: nsu = http://samples.org/UA/memorybuffer ;ns=7;i=1025
#nodeElement.NodeId.ExpandedText: nsu = http://samples.org/UA/memorybuffer ;ns=7;i=1025
# This example shows how to obtain all data nodes (objects and variables) under a given node of the OPC-UA address space. 
# For each node, it displays its browse name and node ID.
#
# 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 .
# 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.OperationModel import *


endpointDescriptor = UAEndpointDescriptor('opc.tcp://opcua.demo-this.com:51210/UA/SampleServer')
# or 'http://opcua.demo-this.com:51211/UA/SampleServer' (currently not supported)
# or 'https://opcua.demo-this.com:51212/UA/SampleServer/'

# Instantiate the client object.
client = EasyUAClient()

# Obtain data nodes under "Objects" node.
try:
    nodeElementCollection = IEasyUAClientExtension.BrowseDataNodes(client, endpointDescriptor)
except UAException as uaException:
    print('*** Failure: ' + uaException.GetBaseException().Message)
    exit()

# Display results.
for nodeElement in nodeElementCollection:
    print()
    print('nodeElement.DisplayName: ', nodeElement.DisplayName, sep='')
    print('nodeElement.NodeId: ', nodeElement.NodeId, sep='')
    print('nodeElement.NodeId.ExpandedText: ', nodeElement.NodeId.ExpandedText, sep='')

print()
print('Finished.')
' This example shows how to obtain "data nodes" (objects, variables and properties) under the "Objects" node in the address
' space.
'
' Find all latest examples here: https://opclabs.doc-that.com/files/onlinedocs/OPCLabs-OpcStudio/Latest/examples.html .

Imports OpcLabs.EasyOpc.UA
Imports OpcLabs.EasyOpc.UA.AddressSpace
Imports OpcLabs.EasyOpc.UA.OperationModel

Namespace _EasyUAClient
    Friend Class BrowseDataNodes
        Public Shared Sub Overload1()

            ' Define which server we will work with.
            Dim endpointDescriptor As UAEndpointDescriptor =
                    "opc.tcp://opcua.demo-this.com:51210/UA/SampleServer"
            ' or "http://opcua.demo-this.com:51211/UA/SampleServer" (currently not supported)
            ' or "https://opcua.demo-this.com:51212/UA/SampleServer/"

            ' Instantiate the client object
            Dim client = New EasyUAClient()

            ' Obtain data nodes under "Objects" node
            Dim nodeElementCollection As UANodeElementCollection
            Try
                nodeElementCollection = client.BrowseDataNodes(endpointDescriptor)
            Catch uaException As UAException
                Console.WriteLine("*** Failure: {0}", uaException.GetBaseException.Message)
                Exit Sub
            End Try

            ' Display results
            For Each nodeElement As UANodeElement In nodeElementCollection
                Console.WriteLine()
                Console.WriteLine("nodeElement.NodeId: {0}", nodeElement.NodeId)
                Console.WriteLine("nodeElement.DisplayName: {0}", nodeElement.DisplayName)
            Next nodeElement

            ' Example output:
            '
            'nodeElement.NodeId: nsu=http://opcfoundation.org/UA/;i=2253
            'nodeElement.DisplayName: Server
            '
            'nodeElement.NodeId: nsu=http://test.org/UA/Data/ ;i=10157
            'nodeElement.DisplayName: Data
            '
            'nodeElement.NodeId: nsu=http://opcfoundation.org/UA/Boiler/;i=1240
            'nodeElement.DisplayName: Boilers
            '
            'nodeElement.NodeId: nsu=http://samples.org/UA/memorybuffer;i=1025
            'nodeElement.DisplayName: MemoryBuffers            
        End Sub
    End Class
End Namespace
// This example shows how to obtain "data nodes" under the "Objects" node, recursively.
//
// Find all latest examples here: https://opclabs.doc-that.com/files/onlinedocs/OPCLabs-OpcStudio/Latest/examples.html .

using System;
using System.Diagnostics;
using OpcLabs.EasyOpc.UA;
using OpcLabs.EasyOpc.UA.AddressSpace;
using OpcLabs.EasyOpc.UA.AddressSpace.Standard;
using OpcLabs.EasyOpc.UA.OperationModel;

namespace UADocExamples._EasyUAClient
{
    partial class BrowseDataNodes
    {
        public static void Recursive()
        {
            UAEndpointDescriptor endpointDescriptor =
                "opc.tcp://opcua.demo-this.com:51210/UA/SampleServer";
            // or "http://opcua.demo-this.com:51211/UA/SampleServer" (currently not supported)
            // or "https://opcua.demo-this.com:51212/UA/SampleServer/"

            // Instantiate the client object
            var client = new EasyUAClient();

            try
            {
                BrowseFromNode(client, endpointDescriptor, UAObjectIds.ObjectsFolder, level:0);
            }
            catch (UAException uaException)
            {
                Console.WriteLine($"*** Failure: {uaException.GetBaseException().Message}");
            }
        }

        private static void BrowseFromNode(
            EasyUAClient client,
            UAEndpointDescriptor endpointDescriptor,
            UANodeDescriptor parentNodeDescriptor,
            int level)
        {
            Debug.Assert(!(client is null));
            Debug.Assert(!(endpointDescriptor is null));
            Debug.Assert(!(parentNodeDescriptor is null));

            // Obtain all node elements under parentNodeDescriptor
            UANodeElementCollection nodeElementCollection = 
                client.BrowseDataNodes(endpointDescriptor, parentNodeDescriptor);
            // Remark: BrowseDataNodes(...) may throw UAException; we handle it in the calling method.

            foreach (UANodeElement nodeElement in nodeElementCollection)
            {
                Debug.Assert(!(nodeElement is null));

                Console.Write(new string(' ', level*2));    // indent
                Console.WriteLine(nodeElement);

                // Browse recursively into the node.
                // The UANodeElement has an implicit conversion to UANodeDescriptor.
                BrowseFromNode(client, endpointDescriptor, nodeElement, level + 1);

                // Note that the number of nodes you obtain through recursive browsing may be very large, or even infinite.
                // Production code should contain appropriate safeguards for these cases.
            }
        }


        // Example output:
        //
        //ServerStatus -> nsu=http://opcfoundation.org/UA/ ;i=2256 (Variable) 
        //  StartTime -> nsu=http://opcfoundation.org/UA/ ;i=2257 (Variable) 
        //  CurrentTime -> nsu=http://opcfoundation.org/UA/ ;i=2258 (Variable) 
        //  State -> nsu=http://opcfoundation.org/UA/ ;i=2259 (Variable) 
        //  BuildInfo -> nsu=http://opcfoundation.org/UA/ ;i=2260 (Variable) 
        //    ProductUri -> nsu=http://opcfoundation.org/UA/ ;i=2262 (Variable) 
        //    ManufacturerName -> nsu=http://opcfoundation.org/UA/ ;i=2263 (Variable) 
        //    ProductName -> nsu=http://opcfoundation.org/UA/ ;i=2261 (Variable) 
        //    SoftwareVersion -> nsu=http://opcfoundation.org/UA/ ;i=2264 (Variable) 
        //    BuildNumber -> nsu=http://opcfoundation.org/UA/ ;i=2265 (Variable) 
        //    BuildDate -> nsu=http://opcfoundation.org/UA/ ;i=2266 (Variable) 
        //  SecondsTillShutdown -> nsu=http://opcfoundation.org/UA/ ;i=2992 (Variable) 
        //  ShutdownReason -> nsu=http://opcfoundation.org/UA/ ;i=2993 (Variable) 
        //ServerCapabilities -> nsu=http://opcfoundation.org/UA/ ;i=2268 (Object) 
        //  OperationLimits -> nsu=http://opcfoundation.org/UA/ ;i=11704 (Object) 
        //    MaxNodesPerRead -> nsu=http://opcfoundation.org/UA/ ;i=11705 (Variable) 
        //    MaxNodesPerHistoryReadData -> nsu=http://opcfoundation.org/UA/ ;i=12165 (Variable) 
        //    MaxNodesPerHistoryReadEvents -> nsu=http://opcfoundation.org/UA/ ;i=12166 (Variable) 
        //    MaxNodesPerWrite -> nsu=http://opcfoundation.org/UA/ ;i=11707 (Variable) 
        //    MaxNodesPerHistoryUpdateData -> nsu=http://opcfoundation.org/UA/ ;i=12167 (Variable) 
        //...
    }
}
# This example shows how to obtain "data nodes" under the "Objects" node, recursively.
#
# 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 .
# 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.AddressSpace.Standard import *
from OpcLabs.EasyOpc.UA.OperationModel import *


def browseFromNode(client, endpointDescriptor, parentNodeDescriptor, level):
    assert client is not None
    assert endpointDescriptor is not None
    assert parentNodeDescriptor is not None

    # Obtain all node elements under parentNodeDescriptor
    nodeElementCollection = IEasyUAClientExtension.BrowseDataNodes(client, endpointDescriptor, parentNodeDescriptor)
    # Remark: BrowseDataNodes(...) may throw UAException; we handle it in the calling method.
    #
    for nodeElement in nodeElementCollection:
        assert nodeElement is not None

        print(' '*(level*2), end='')    # indent
        print(nodeElement)

        # Browse recursively into the node.
        # The UANodeElement has an implicit conversion to UANodeDescriptor.
        browseFromNode(client, endpointDescriptor, nodeElement.ToUANodeDescriptor(), level + 1)

        # Note that the number of nodes you obtain through recursive browsing may be very large, or even infinite.
        # Production code should contain appropriate safeguards for these cases.


endpointDescriptor = UAEndpointDescriptor('opc.tcp://opcua.demo-this.com:51210/UA/SampleServer')
# or 'http://opcua.demo-this.com:51211/UA/SampleServer' (currently not supported)
# or 'https://opcua.demo-this.com:51212/UA/SampleServer/'

# Instantiate the client object.
client = EasyUAClient()

try:
    browseFromNode(client, endpointDescriptor, UANodeDescriptor(UAObjectIds.ObjectsFolder), 0)
except UAException as uaException:
    print('*** Failure: ' + uaException.GetBaseException().Message)
    exit()

print()
print('Finished.')
' This example shows how to obtain "data nodes" under the "Objects" node, recursively.
'
' Find all latest examples here: https://opclabs.doc-that.com/files/onlinedocs/OPCLabs-OpcStudio/Latest/examples.html .

Imports OpcLabs.EasyOpc.UA
Imports OpcLabs.EasyOpc.UA.AddressSpace
Imports OpcLabs.EasyOpc.UA.AddressSpace.Standard
Imports OpcLabs.EasyOpc.UA.OperationModel

Namespace _EasyUAClient
    Partial Friend Class BrowseDataNodes
        Public Shared Sub Recursive()

            ' Define which server we will work with.
            Dim endpointDescriptor As UAEndpointDescriptor =
                    "opc.tcp://opcua.demo-this.com:51210/UA/SampleServer"
            ' or "http://opcua.demo-this.com:51211/UA/SampleServer" (currently not supported)
            ' or "https://opcua.demo-this.com:51212/UA/SampleServer/"

            ' Instantiate the client object
            Dim client = New EasyUAClient()
            Try
                BrowseFromNode(client, endpointDescriptor, UAObjectIds.ObjectsFolder, level:=0)
            Catch uaException As UAException
                Console.WriteLine($"*** Failure: {uaException.GetBaseException().Message}")
                Exit Sub
            End Try
        End Sub

        Private Shared Sub BrowseFromNode(client As EasyUAClient, endPointDescriptor As UAEndpointDescriptor, parentNodeDescriptor As UANodeDescriptor, level As Integer)
            Debug.Assert(client IsNot Nothing)
            Debug.Assert(endPointDescriptor IsNot Nothing)
            Debug.Assert(parentNodeDescriptor IsNot Nothing)

            ' Obtain all node elements under parentNodeDescriptor
            Dim nodeElementCollection As UANodeElementCollection =
                client.BrowseDataNodes(endPointDescriptor, parentNodeDescriptor)
            ' Remark: BrowseDataNodes(...) may throw UAException; we handle it in the calling method.

            For Each nodeElement As UANodeElement In nodeElementCollection
                Debug.Assert(nodeElement IsNot Nothing)

                Console.Write(New String(" "c, level * 2))
                Console.WriteLine(nodeElement)

                ' Browse recursively into the node.
                ' The UANodeElement has an implicit conversion to UANodeDescriptor.
                BrowseFromNode(client, endPointDescriptor, nodeElement, level + 1)

                ' Note that the number of nodes you obtain through recursive browsing may be very large, or even infinite.
                ' Production code should contain appropriate safeguards for these cases.
            Next nodeElement
        End Sub
    End Class
End Namespace
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