EventWatcherOptions Constructors
Definition
Important
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Initializes a new instance of the EventWatcherOptions class for event watching.
Overloads
| 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. |
EventWatcherOptions()
- Source:
- ManagementOptions.cs
- Source:
- ManagementOptions.cs
Initializes a new instance of the EventWatcherOptions class for event watching, using default values. This is the parameterless constructor.
public:
EventWatcherOptions();public EventWatcherOptions ();Public Sub New ()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
Remarks
.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.
Applies to
EventWatcherOptions(ManagementNamedValueCollection, TimeSpan, Int32)
- Source:
- ManagementOptions.cs
- Source:
- ManagementOptions.cs
Initializes a new instance of the EventWatcherOptions class with the given values.
public:
EventWatcherOptions(System::Management::ManagementNamedValueCollection ^ context, TimeSpan timeout, int blockSize);public EventWatcherOptions (System.Management.ManagementNamedValueCollection context, TimeSpan timeout, int blockSize);new System.Management.EventWatcherOptions : System.Management.ManagementNamedValueCollection * TimeSpan * int -> System.Management.EventWatcherOptionsPublic Sub New (context As ManagementNamedValueCollection, timeout As TimeSpan, blockSize As Integer)Parameters
- context
- ManagementNamedValueCollection
The options context object containing provider-specific information to be passed through to the provider.
- timeout
- TimeSpan
The time-out to wait for the next events.
- blockSize
- Int32
The number of events to wait for in each block.
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
// blockSize = 1 to receive one event
EventWatcherOptions eventOptions = new
EventWatcherOptions(null, System.TimeSpan.MaxValue,
1);
// 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
' blockSize = 1 to receive one event
Dim eventOptions As New EventWatcherOptions( _
Nothing, System.TimeSpan.MaxValue, 1)
' 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
Remarks
.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.
