BrowseNodes Method (EasyAEClientCore)

Browses the specified area (or root) in OPC server's process area space, and returns information about child nodes (areas or sources) found. Uses server descriptor for specifying the OPC server. A parent area descriptor is passed in. No vendor-specific filtering.

Syntax

Visual Basic
C#
C++/CLI

'Declaration
 
Public Function BrowseNodes( _
   ByVal serverDescriptor As ServerDescriptor, _
   ByVal parentNodeDescriptor As AENodeDescriptor, _
   ByVal browseParameters As AEBrowseParameters _
) As AENodeElementCollection

'Usage
 
Dim instance As EasyAEClientCore
Dim serverDescriptor As ServerDescriptor
Dim parentNodeDescriptor As AENodeDescriptor
Dim browseParameters As AEBrowseParameters
Dim value As AENodeElementCollection
 
value = instance.BrowseNodes(serverDescriptor, parentNodeDescriptor, browseParameters)

public AENodeElementCollection BrowseNodes( 
   ServerDescriptor serverDescriptor,
   AENodeDescriptor parentNodeDescriptor,
   AEBrowseParameters browseParameters
)

public:
AENodeElementCollection^ BrowseNodes( 
   ServerDescriptor^ serverDescriptor,
   AENodeDescriptor^ parentNodeDescriptor,
   AEBrowseParameters^ browseParameters
)

Parameters

serverDescriptor

The OPC server involved in the operation.

Because the OpcLabs.EasyOpc.ServerDescriptor has an implicit conversion from System.Guid, System.String and OpcLabs.EasyOpc.ServerElement, in languages that support implicit conversion operators (such as C# or VB.NET), you can simply use a GUID (representing the CLSID of the server), a string (representing the so-called OPC server descriptor string, such as a ProgID or the URL of the server), or a OpcLabs.EasyOpc.ServerElement object (result from OPC browsing), in place of this parameter, and the corresponding OPC server descriptor will be constructed automatically. When the implicit conversion operators are not supported (such as with Python.NET), you can use the OpcLabs.EasyOpc.ServerDescriptor.FromGuid, OpcLabs.EasyOpc.ServerDescriptor.FromString or OpcLabs.EasyOpc.ServerDescriptor.FromServerElement static method instead.

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

parentNodeDescriptor

Descriptor for the parent area to be browsed (can be the root).

Because the AENodeDescriptor has an implicit conversion from System.String and OpcLabs.EasyOpc.AlarmsAndEvents.AddressSpace.AENodeElement, in languages that support implicit conversion operators (such as C# or VB.NET), you can simply use a string (representing the qualified name of the node), or a OpcLabs.EasyOpc.AlarmsAndEvents.AddressSpace.AENodeElement object (result from OPC browsing), in place of this parameter, and the corresponding OPC A&E node descriptor will be constructed automatically. When the implicit conversion operators are not supported (such as with Python.NET), you can use the AENodeDescriptor.FromString or AENodeDescriptor.FromAENodeElement static method instead.

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

browseParameters

Contains filtering conditions.

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 node (area or source) found. The keys of the keyed collection are the names of the nodes.

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

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

Exceptions

Exception Description

Exception	Description
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.

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.

Requirements

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

Reference

EasyAEClientCore Class
EasyAEClientCore Members

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