OPC Studio User's Guide and Reference
BrowseTree(IEasyAEClient,ServerDescriptor,AENodeDescriptor,AEBrowseParameters) Method



OpcLabs.EasyOpcClassicCore Assembly > OpcLabs.EasyOpc.AlarmsAndEvents.Extensions Namespace > IEasyAEClientExtension2 Class > BrowseTree Method : BrowseTree(IEasyAEClient,ServerDescriptor,AENodeDescriptor,AEBrowseParameters) Method
The client object that will perform the operation.

This is typically the OpcLabs.EasyOpc.AlarmsAndEvents.EasyAEClient object.

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

Server descriptor. Identifies the OPC-A&E server.

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 FromGuid, FromString or FromServerElement static method instead.

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

Starting node descriptor. Identifies the node in OPC server's address space.

Because the OpcLabs.EasyOpc.AlarmsAndEvents.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 FromString or FromAENodeElement static method instead.

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

Contains filtering conditions for OPC Alarms&Events node browsing.

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

Allows to traverse through OPC A&E address space nodes under the specified node, using given browse parameters.
Syntax
'Declaration
 
<ExtensionAttribute()>
<NotNullAttribute()>
Public Overloads Shared Function BrowseTree( _
   ByVal client As IEasyAEClient, _
   ByVal serverDescriptor As ServerDescriptor, _
   ByVal nodeDescriptor As AENodeDescriptor, _
   ByVal browseParameters As AEBrowseParameters _
) As ITreeTraversable(Of AENodeTreePosition)
'Usage
 
Dim client As IEasyAEClient
Dim serverDescriptor As ServerDescriptor
Dim nodeDescriptor As AENodeDescriptor
Dim browseParameters As AEBrowseParameters
Dim value As ITreeTraversable(Of AENodeTreePosition)
 
value = IEasyAEClientExtension2.BrowseTree(client, serverDescriptor, nodeDescriptor, browseParameters)

Parameters

client
The client object that will perform the operation.

This is typically the OpcLabs.EasyOpc.AlarmsAndEvents.EasyAEClient object.

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

serverDescriptor
Server descriptor. Identifies the OPC-A&E server.

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 FromGuid, FromString or FromServerElement static method instead.

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

nodeDescriptor
Starting node descriptor. Identifies the node in OPC server's address space.

Because the OpcLabs.EasyOpc.AlarmsAndEvents.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 FromString or FromAENodeElement static method instead.

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

browseParameters
Contains filtering conditions for OPC Alarms&Events node browsing.

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

Return Value

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

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

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.

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.AlarmsAndEvents.Graphs.AENodeTreePosition object for the root is special one, in that from its OpcLabs.EasyOpc.AlarmsAndEvents.AddressSpace.AENodeElement properties, only its QualifiedName is filled in.

You can obtain nodeDescriptor e.g. by calling one of the browsing methods on OpcLabs.EasyOpc.AlarmsAndEvents.IEasyAEClient interface.

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.

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