QuickOPC User's Guide and Reference
SubscribeTarget(DAClientMapper,Boolean,Predicate<IEnumerable<String>>,Object,Boolean) Method



OpcLabs.EasyOpcClassic Assembly > OpcLabs.EasyOpc.DataAccess.LiveMapping.Extensions Namespace > DAClientMapperExtension Class > SubscribeTarget Method : SubscribeTarget(DAClientMapper,Boolean,Predicate<IEnumerable<String>>,Object,Boolean) Method
The client mapper object that will perform the operation.
true to subscribe; false to unsubscribe.
The operation will be performed only on mappings whose mapping tags satisfy this predicate.
The object being targeted.
true to operate on sub-targets (mapped members of the target) recursively; false otherwise.
Executes the "Subscribe" operation on members of given target object.
Syntax
'Declaration
 
<ExtensionAttribute()>
Public Overloads Shared Sub SubscribeTarget( _
   ByVal clientMapper As DAClientMapper, _
   ByVal active As Boolean, _
   ByVal mappingTagsPredicate As Predicate(Of IEnumerable(Of String)), _
   ByVal targetObject As Object, _
   ByVal recurse As Boolean _
) 
'Usage
 
Dim clientMapper As DAClientMapper
Dim active As Boolean
Dim mappingTagsPredicate As Predicate(Of IEnumerable(Of String))
Dim targetObject As Object
Dim recurse As Boolean
 
DAClientMapperExtension.SubscribeTarget(clientMapper, active, mappingTagsPredicate, targetObject, recurse)

Parameters

clientMapper
The client mapper object that will perform the operation.
active
true to subscribe; false to unsubscribe.
mappingTagsPredicate
The operation will be performed only on mappings whose mapping tags satisfy this predicate.
targetObject
The object being targeted.
recurse
true to operate on sub-targets (mapped members of the target) recursively; false otherwise.
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 component is not licensed for the operation requested.
Remarks
The "Subscribe" operation subscribes to or unsubscribes from changes of an OPC item. Only mappings of type OpcLabs.EasyOpc.DataAccess.LiveMapping.DAItemMapping that include OpcLabs.EasyOpc.DataAccess.LiveMapping.DAItemMappingOperations.Subscribe in their OpcLabs.EasyOpc.DataAccess.LiveMapping.DAClientItemMapping.Operations are affected; other mappings are ignored.
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