BrowseTree(IEasyDAClient,ServerDescriptor,DANodeDescriptor,DABrowseParameters,Predicate<DANodeElement>) Method

Allows to traverse through OPC DA address space nodes under the specified node, using given browse parameters, and allowing only nodes that fulfill a specified predicate into the traversal.

Syntax

Visual Basic
C#
C++/CLI

'Declaration
 
<ExtensionAttribute()>
<NotNullAttribute()>
Public Overloads Shared Function BrowseTree( _
   ByVal client As IEasyDAClient, _
   ByVal serverDescriptor As ServerDescriptor, _
   ByVal nodeDescriptor As DANodeDescriptor, _
   ByVal browseParameters As DABrowseParameters, _
   ByVal nodeElementPredicate As Predicate(Of DANodeElement) _
) As ITreeTraversable(Of DANodeTreePosition)

'Usage
 
Dim client As IEasyDAClient
Dim serverDescriptor As ServerDescriptor
Dim nodeDescriptor As DANodeDescriptor
Dim browseParameters As DABrowseParameters
Dim nodeElementPredicate As Predicate(Of DANodeElement)
Dim value As ITreeTraversable(Of DANodeTreePosition)
 
value = IEasyDAClientExtension2.BrowseTree(client, serverDescriptor, nodeDescriptor, browseParameters, nodeElementPredicate)

[Extension()]
[NotNull()]
public static ITreeTraversable<DANodeTreePosition> BrowseTree( 
   IEasyDAClient client,
   ServerDescriptor serverDescriptor,
   DANodeDescriptor nodeDescriptor,
   DABrowseParameters browseParameters,
   Predicate<DANodeElement> nodeElementPredicate
)

[Extension()]
[NotNull()]
public:
static ITreeTraversable<DANodeTreePosition^>^ BrowseTree( 
   IEasyDAClient^ client,
   ServerDescriptor^ serverDescriptor,
   DANodeDescriptor^ nodeDescriptor,
   DABrowseParameters^ browseParameters,
   Predicate<DANodeElement^>^ nodeElementPredicate
)

Parameters

client: The client object that will perform the operation.
serverDescriptor: Server descriptor. Identifies the OPC-DA server.
nodeDescriptor: Starting node descriptor. Identifies the node in OPC server's address space.
browseParameters: Contains filtering conditions for OPC Data Access node browsing.
nodeElementPredicate: The predicate specifying which nodes will be allowed into the traversal.

Return Value

Returns an enumerator of tree positions that will traverse through all nodes specified.

Exceptions

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.

Remarks

If you want to enumerate through a sequence of the tree nodes, convert the result to a sequence using the OpcLabs.BaseLib.Graphs.Extensions.ITreeTraversableExtension.ToEnumerable<T> method.

The method automatically prevents recursion into nodes that have already been traversed.

The root position in a tree will correspond to the specified starting node. The OpcLabs.EasyOpc.DataAccess.Graphs.DANodeTreePosition object for the root is special one, in that from its OpcLabs.EasyOpc.DataAccess.AddressSpace.DANodeElement properties, only its ItemId is filled in.

You can obtain nodeDescriptor e.g. by calling one of the browsing methods on OpcLabs.EasyOpc.DataAccess.EasyDAClient object.

Requirements

Target Platforms: .NET Framework: Windows 10 (selected versions), Windows 11 (selected versions), Windows Server 2012, Windows Server 2016; .NET Core, .NET 5, .NET 6: Linux, macOS, Microsoft Windows

Reference

IEasyDAClientExtension2 Class
IEasyDAClientExtension2 Members
Overload List