OPC Studio User's Guide and Reference
BrowseAreas(IEasyAEClient,String,String,String,String) Method
Example 



OpcLabs.EasyOpcClassicCore Assembly > OpcLabs.EasyOpc.AlarmsAndEvents Namespace > IEasyAEClientExtension Class > BrowseAreas Method : BrowseAreas(IEasyAEClient,String,String,String,String) Method
The client object that will perform the operation.

This is typically the EasyAEClient object.

The value of this parameter cannot be null (Nothing in Visual Basic).

Name of the machine. Determines the computer on which the OPC server is located. It may be an empty string, in which case the OPC server is assumed to exist on the local computer or at the computer specified for it by DCOM configuration.

The value represents a UNC or DNS computer name. Any string can be passed to this parameter (i.e. will not cause System.ArgumentException), but not all values make sense and will work when an operation using them is attempted. IPv6 addresses are normally enclosed between '[' and ']'.

The value of this parameter cannot be null (Nothing in Visual Basic).

Contains ProgID of the OPC server.

The value of this parameter cannot be null (Nothing in Visual Basic).

Fully qualified name of the parent area to be browsed (empty string for root)

The value of this parameter cannot be null (Nothing in Visual Basic).

A server specific filter string (empty string for no filtering)

The value of this parameter cannot be null (Nothing in Visual Basic).

Browses the specified area for child areas. Uses computer name and server class for specifying the OPC server. A parent area, and a filter is passed in.
Syntax
'Declaration
 

<ExtensionAttribute()>
<NotNullAttribute()>
Public Overloads Shared Function BrowseAreas( _
   ByVal client As IEasyAEClient, _
   ByVal machineName As String, _
   ByVal serverClass As String, _
   ByVal parentQualifiedName As String, _
   ByVal vendorFilter As String _
) As AENodeElementCollection
'Usage
 

Dim client As IEasyAEClient
Dim machineName As String
Dim serverClass As String
Dim parentQualifiedName As String
Dim vendorFilter As String
Dim value As AENodeElementCollection
 
value = IEasyAEClientExtension.BrowseAreas(client, machineName, serverClass, parentQualifiedName, vendorFilter)
[Extension()]
[NotNull()]
public static AENodeElementCollection BrowseAreas( 
   IEasyAEClient client,
   string machineName,
   string serverClass,
   string parentQualifiedName,
   string vendorFilter
)
[Extension()]
[NotNull()]
public:
static AENodeElementCollection^ BrowseAreas( 
   IEasyAEClient^ client,
   String^ machineName,
   String^ serverClass,
   String^ parentQualifiedName,
   String^ vendorFilter
)

Parameters

client
The client object that will perform the operation.

This is typically the EasyAEClient object.

The value of this parameter cannot be null (Nothing in Visual Basic).

machineName
Name of the machine. Determines the computer on which the OPC server is located. It may be an empty string, in which case the OPC server is assumed to exist on the local computer or at the computer specified for it by DCOM configuration.

The value represents a UNC or DNS computer name. Any string can be passed to this parameter (i.e. will not cause System.ArgumentException), but not all values make sense and will work when an operation using them is attempted. IPv6 addresses are normally enclosed between '[' and ']'.

The value of this parameter cannot be null (Nothing in Visual Basic).

serverClass
Contains ProgID of the OPC server.

The value of this parameter cannot be null (Nothing in Visual Basic).

parentQualifiedName
Fully qualified name of the parent area to be browsed (empty string for root)

The value of this parameter cannot be null (Nothing in Visual Basic).

vendorFilter
A server specific filter string (empty string for no filtering)

The value of this parameter cannot be null (Nothing in Visual Basic).

Return Value

The method returns a keyed collection of OpcLabs.EasyOpc.AlarmsAndEvents.AddressSpace.AENodeElement values, each containing information about a particular area found. The keys of the keyed collection are the names of the areas.

This method never returns null (Nothing in Visual Basic).

The individual elements of the returned value are never null (Nothing in Visual Basic).

Exceptions
ExceptionDescription
System.ArgumentNullException

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.

OpcLabs.EasyOpc.OperationModel.OpcException

The OPC "Classic" (or OPC XML-DA) 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 is an extension method (info: C#, VB.NET). In languages that have support for extensions methods (such as C# and VB.NET), you can use the extension method as if it were a regular method on the object that is its first parameter. In other languages (such as with Python.NET), you will call the extension as a static method, and pass it the object on which it acts as its first parameter.

Example
// This example shows how to obtain all areas directly under the root (denoted by empty string for the parent).
//
// 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 System.Diagnostics;
using OpcLabs.EasyOpc.AlarmsAndEvents;
using OpcLabs.EasyOpc.AlarmsAndEvents.AddressSpace;
using OpcLabs.EasyOpc.OperationModel;

namespace DocExamples.AlarmsAndEvents._EasyAEClient
{
    class BrowseAreas 
    { 
        public static void Main1()
        {
            // Instantiate the client object.
            var client = new EasyAEClient();

            AENodeElementCollection nodeElements;
            try
            {
                nodeElements = client.BrowseAreas("", "OPCLabs.KitEventServer.2", "");
            }
            catch (OpcException opcException)
            {
                Console.WriteLine("*** Failure: {0}", opcException.GetBaseException().Message);
                return;
            }

            foreach (AENodeElement nodeElement in nodeElements)
            {
                Debug.Assert(nodeElement != null);

                Console.WriteLine("nodeElements[\"{0}\"]:", nodeElement.Name);
                Console.WriteLine("    .QualifiedName: {0}", nodeElement.QualifiedName);
            }
        }
    } 
}
' This example shows how to obtain all areas directly under the root (denoted by empty string for the parent).
'
' 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.AlarmsAndEvents
Imports OpcLabs.EasyOpc.AlarmsAndEvents.AddressSpace
Imports OpcLabs.EasyOpc.OperationModel

Namespace AlarmsAndEvents._EasyAEClient

    Friend Class BrowseAreas
        Public Shared Sub Main1()
            Dim client = New EasyAEClient()

            Dim nodeElements As AENodeElementCollection
            Try
                nodeElements = client.BrowseAreas("", "OPCLabs.KitEventServer.2", "")
            Catch opcException As OpcException
                Console.WriteLine("*** Failure: {0}", opcException.GetBaseException().Message)
                Exit Sub
            End Try

            For Each nodeElement As AENodeElement In nodeElements
                Debug.Assert(nodeElement IsNot Nothing)

                Console.WriteLine("nodeElements[""{0}""]:", nodeElement.Name)
                Console.WriteLine("    .QualifiedName: {0}", nodeElement.QualifiedName)
            Next nodeElement
        End Sub
    End Class

End Namespace
# This example shows how to obtain all areas directly under the root (denoted by empty string for the parent).
#
# 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 import *
from OpcLabs.EasyOpc.AlarmsAndEvents import *
from OpcLabs.EasyOpc.OperationModel import *


# Instantiate the client object
client = EasyAEClient()

# Perform the operation
try:
    nodeElements = IEasyAEClientExtension.BrowseAreas(client, '', 'OPCLabs.KitEventServer.2', '')
except OpcException as opcException:
    print('*** Failure: ' + opcException.GetBaseException().Message)
    exit()

# Display results
for nodeElement in nodeElements:
    assert nodeElement is not None
    print('NodeElements["', nodeElement.Name, '"]:', sep='')
    print('    .QualifiedName: ', nodeElement.QualifiedName, sep='')
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

IEasyAEClientExtension Class
IEasyAEClientExtension Members
Overload List

 

 

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