EventWatcherOptions Class
Definition
Important
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Specifies options for management event watching.
public ref class EventWatcherOptions : System::Management::ManagementOptions
public class EventWatcherOptions : System.Management.ManagementOptions
type EventWatcherOptions = class
inherit ManagementOptions
Public Class EventWatcherOptions
Inherits ManagementOptions
- Inheritance
Examples
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. 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.
using System;
using System.Management;
// This example shows synchronous consumption of events.
// The client is blocked while waiting for events.
public class EventWatcherPolling
{
public static int Main(string[] args)
{
// Create event query to be notified within 1 second of
// a change in a service
string query = "SELECT * FROM" +
" __InstanceCreationEvent WITHIN 1 " +
"WHERE TargetInstance isa \"Win32_Process\"";
// Event options
EventWatcherOptions eventOptions = new
EventWatcherOptions();
eventOptions.Timeout = System.TimeSpan.MaxValue;
// Initialize an event watcher and subscribe to events
// that match this query
ManagementEventWatcher watcher =
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.");
ManagementBaseObject e = watcher.WaitForNextEvent();
//Display information from the event
Console.WriteLine(
"Process {0} has been created, path is: {1}",
((ManagementBaseObject)e
["TargetInstance"])["Name"],
((ManagementBaseObject)e
["TargetInstance"])["ExecutablePath"]);
//Cancel the subscription
watcher.Stop();
return 0;
}
}
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
Constructors
EventWatcherOptions() |
Initializes a new instance of the EventWatcherOptions class for event watching, using default values. This is the parameterless constructor. |
EventWatcherOptions(ManagementNamedValueCollection, TimeSpan, Int32) |
Initializes a new instance of the EventWatcherOptions class with the given values. |
Properties
BlockSize |
Gets or sets the block size for block operations. When waiting for events, this value specifies how many events to wait for before returning. |
Context |
Gets or sets a WMI context object. This is a name-value pairs list to be passed through to a WMI provider that supports context information for customized operation. (Inherited from ManagementOptions) |
Timeout |
Gets or sets the time-out to apply to the operation. Note that for operations that return collections, this time-out applies to the enumeration through the resulting collection, not the operation itself (the ReturnImmediately property is used for the latter). This property is used to indicate that the operation should be performed semi-synchronously. (Inherited from ManagementOptions) |
Methods
Clone() |
Returns a copy of the object. |
Equals(Object) |
Determines whether the specified object is equal to the current object. (Inherited from Object) |
GetHashCode() |
Serves as the default hash function. (Inherited from Object) |
GetType() |
Gets the Type of the current instance. (Inherited from Object) |
MemberwiseClone() |
Creates a shallow copy of the current Object. (Inherited from Object) |
ToString() |
Returns a string that represents the current object. (Inherited from Object) |
Applies to
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