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EventWatcherOptions Constructor

Initializes a new instance of the EventWatcherOptions class for event watching, using default values. This is the default constructor.

Namespace:  System.Management
Assembly:  System.Management (in System.Management.dll)

'Declaration
Public Sub New

.NET Framework Security

Full trust for the immediate caller. This member cannot be used by partially trusted code. For more information, see Using Libraries from Partially Trusted Code.

The following example shows how the client receives notification when an instance of Win32_Process is created because the event class is __InstanceCreationEvent. For more information, see the Windows Management Instrumentation documentation in the MSDN Library at http://msdn.microsoft.com/library. The client receives events synchronously by calling the WaitForNextEvent method. This example can be tested by starting a process, such as Notepad, while the example code is running.

Imports System
Imports System.Management

' This example shows synchronous consumption of events.  
' The client is blocked while waiting for events.  

Public Class EventWatcherPolling
    Public Overloads Shared Function _
        Main(ByVal args() As String) As Integer 

        ' Create event query to be notified within 1 second of  
        ' a change in a service 
        Dim query As String
        query = "SELECT * FROM" & _
            " __InstanceCreationEvent WITHIN 1 " & _
            "WHERE TargetInstance isa ""Win32_Process""" 

        ' Event options 
        Dim eventOptions As New EventWatcherOptions
        eventOptions.Timeout = System.TimeSpan.MaxValue

        ' Initialize an event watcher and subscribe to events  
        ' that match this query 
        Dim watcher As New ManagementEventWatcher( _
            "root\CIMV2", query, eventOptions)

        ' Block until the next event occurs  
        ' Note: this can be done in a loop 
        ' if waiting for more than one occurrence
        Console.WriteLine( _
          "Open an application (notepad.exe) to trigger an event.")
        Dim e As ManagementBaseObject = _
            watcher.WaitForNextEvent()

        'Display information from the event
        Console.WriteLine( _
            "Process {0} has created, path is: {1}", _
            CType(e("TargetInstance"), _
                ManagementBaseObject)("Name"), _
            CType(e("TargetInstance"), _
                ManagementBaseObject)("ExecutablePath"))

        'Cancel the subscription
        watcher.Stop()
        Return 0

    End Function 'Main
End Class 'EventWatcherPolling

.NET Framework

Supported in: 4.6, 4.5, 4, 3.5, 3.0, 2.0, 1.1

.NET Framework Client Profile

Supported in: 4, 3.5 SP1
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