ManagementOperationObserver Class
Manages asynchronous operations and handles management information and events received asynchronously.
Assembly: System.Management (in System.Management.dll)
The following example demonstrates how to perform an asynchronous instance enumeration. The example uses the ManagementOperationObserver class to handle management information and events asynchronously.
Imports System Imports System.Management ' This example demonstrates how ' to perform an asynchronous instance enumeration. Public Class EnumerateInstancesAsync Public Sub New() Me.isCompleted = False ' Enumerate asynchronously using Object Searcher ' =============================================== ' Instantiate an object searcher with the query Dim searcher As ManagementObjectSearcher searcher = New ManagementObjectSearcher( _ New SelectQuery("Win32_Service")) ' Create a results watcher object, ' and handler for results and completion Dim results As ManagementOperationObserver results = New ManagementOperationObserver ' Attach handler to events for ' results and completion AddHandler results.ObjectReady, _ AddressOf Me.NewObject AddHandler results.Completed, _ AddressOf Me.Done ' Call the asynchronous overload of ' Get() to start the enumeration searcher.Get(results) ' Do something else while results ' arrive(asynchronously) Do While (Me.Completed.Equals(False)) System.Threading.Thread.Sleep(1000) Loop Me.Reset() End Sub Private isCompleted As Boolean Private Sub NewObject(ByVal sender As Object, _ ByVal e As ObjectReadyEventArgs) Console.WriteLine("Service : {0}, State = {1}", _ e.NewObject("Name"), e.NewObject("State")) End Sub Private ReadOnly Property Completed() As Boolean Get Return isCompleted End Get End Property Private Sub Reset() isCompleted = False End Sub Private Sub Done(ByVal sender As Object, _ ByVal e As CompletedEventArgs) isCompleted = True End Sub Public Shared Function _ Main(ByVal args() As String) As Integer Dim example As New EnumerateInstancesAsync Return 0 End Function End Class
Windows 7, Windows Vista, Windows XP SP2, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP Starter Edition, Windows Server 2008 R2, Windows Server 2008, Windows Server 2003, Windows Server 2000 SP4, Windows Millennium Edition, Windows 98
The .NET Framework and .NET Compact Framework do not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.