ManagementEventWatcher Constructors
Definition
Important
Some information relates to prerelease product that may be substantially modified before it’s released. Microsoft makes no warranties, express or implied, with respect to the information provided here.
Initializes a new instance of the ManagementEventWatcher class.
Overloads
ManagementEventWatcher() |
Initializes a new instance of the ManagementEventWatcher class. For further initialization, set the properties on the object. This is the parameterless constructor. |
ManagementEventWatcher(EventQuery) |
Initializes a new instance of the ManagementEventWatcher class when given a WMI event query. |
ManagementEventWatcher(String) |
Initializes a new instance of the ManagementEventWatcher class when given a WMI event query in the form of a string. |
ManagementEventWatcher(ManagementScope, EventQuery) |
Initializes a new instance of the ManagementEventWatcher class that listens for events conforming to the given WMI event query. |
ManagementEventWatcher(String, String) |
Initializes a new instance of the ManagementEventWatcher class that listens for events conforming to the given WMI event query. For this variant, the query and the scope are specified as strings. |
ManagementEventWatcher(ManagementScope, EventQuery, EventWatcherOptions) |
Initializes a new instance of the ManagementEventWatcher class that listens for events conforming to the given WMI event query, according to the specified options. For this variant, the query and the scope are specified objects. The options object can specify options such as time-out and context information. |
ManagementEventWatcher(String, String, EventWatcherOptions) |
Initializes a new instance of the ManagementEventWatcher class that listens for events conforming to the given WMI event query, according to the specified options. For this variant, the query and the scope are specified as strings. The options object can specify options such as a time-out and context information. |
ManagementEventWatcher()
- Source:
- ManagementEventWatcher.cs
- Source:
- ManagementEventWatcher.cs
- Source:
- ManagementEventWatcher.cs
Initializes a new instance of the ManagementEventWatcher class. For further initialization, set the properties on the object. This is the parameterless constructor.
public:
ManagementEventWatcher();
public ManagementEventWatcher ();
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
WqlEventQuery query =
new WqlEventQuery("__InstanceCreationEvent",
new TimeSpan(0,0,1),
"TargetInstance isa \"Win32_Process\"");
// Initialize an event watcher and subscribe to events
// that match this query
ManagementEventWatcher watcher =
new ManagementEventWatcher();
watcher.Query = query;
// times out watcher.WaitForNextEvent in 5 seconds
watcher.Options.Timeout = new TimeSpan(0,0,5);
// 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 New WqlEventQuery( _
"__InstanceCreationEvent", _
New TimeSpan(0, 0, 1), _
"TargetInstance isa ""Win32_Process""")
' Initialize an event watcher and subscribe to events
' that match this query
Dim watcher As New ManagementEventWatcher
watcher.Query = query
' times watcher.WaitForNextEvent in 5 seconds
watcher.Options.Timeout = New TimeSpan(0, 0, 5)
' 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
ManagementEventWatcher(EventQuery)
- Source:
- ManagementEventWatcher.cs
- Source:
- ManagementEventWatcher.cs
- Source:
- ManagementEventWatcher.cs
Initializes a new instance of the ManagementEventWatcher class when given a WMI event query.
public:
ManagementEventWatcher(System::Management::EventQuery ^ query);
public ManagementEventWatcher (System.Management.EventQuery query);
new System.Management.ManagementEventWatcher : System.Management.EventQuery -> System.Management.ManagementEventWatcher
Public Sub New (query As EventQuery)
Parameters
- query
- EventQuery
An EventQuery representing a WMI event query, which determines the events for which the watcher will listen.
Examples
In this code example, 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\"";
// Initialize an event watcher and subscribe to events
// that match this query
ManagementEventWatcher watcher =
new ManagementEventWatcher(new EventQuery(query));
// times out watcher.WaitForNextEvent in 5 seconds
watcher.Options.Timeout = new TimeSpan(0,0,5);
// 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"""
' Initialize an event watcher and subscribe to events
' that match this query
Dim watcher As New ManagementEventWatcher(New EventQuery( _
query))
' times watcher.WaitForNextEvent in 5 seconds
watcher.Options.Timeout = New TimeSpan(0, 0, 5)
' 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
The namespace in which the watcher will be listening for events is the default namespace that is currently set.
.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
ManagementEventWatcher(String)
- Source:
- ManagementEventWatcher.cs
- Source:
- ManagementEventWatcher.cs
- Source:
- ManagementEventWatcher.cs
Initializes a new instance of the ManagementEventWatcher class when given a WMI event query in the form of a string.
public:
ManagementEventWatcher(System::String ^ query);
public ManagementEventWatcher (string query);
new System.Management.ManagementEventWatcher : string -> System.Management.ManagementEventWatcher
Public Sub New (query As String)
Parameters
- query
- String
A WMI event query, which defines the events for which the watcher will listen.
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\"";
// Initialize an event watcher and subscribe to events
// that match this query
ManagementEventWatcher watcher =
new ManagementEventWatcher(query);
// times out watcher.WaitForNextEvent in 5 seconds
watcher.Options.Timeout = new TimeSpan(0,0,5);
// 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"""
' Initialize an event watcher and subscribe to events
' that match this query
Dim watcher As New ManagementEventWatcher(query)
' times watcher.WaitForNextEvent in 5 seconds
watcher.Options.Timeout = New TimeSpan(0, 0, 5)
' 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
The namespace in which the watcher will be listening for events is the default namespace that is currently set.
.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
ManagementEventWatcher(ManagementScope, EventQuery)
- Source:
- ManagementEventWatcher.cs
- Source:
- ManagementEventWatcher.cs
- Source:
- ManagementEventWatcher.cs
Initializes a new instance of the ManagementEventWatcher class that listens for events conforming to the given WMI event query.
public:
ManagementEventWatcher(System::Management::ManagementScope ^ scope, System::Management::EventQuery ^ query);
public ManagementEventWatcher (System.Management.ManagementScope scope, System.Management.EventQuery query);
new System.Management.ManagementEventWatcher : System.Management.ManagementScope * System.Management.EventQuery -> System.Management.ManagementEventWatcher
Public Sub New (scope As ManagementScope, query As EventQuery)
Parameters
- scope
- ManagementScope
A ManagementScope representing the scope (namespace) in which the watcher will listen for events.
- query
- EventQuery
An EventQuery representing a WMI event query, which determines the events for which the watcher will listen.
Examples
In this code example, 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\"";
// Initialize an event watcher and subscribe to events
// that match this query
ManagementEventWatcher watcher =
new ManagementEventWatcher(
new ManagementScope("root\\CIMV2"),
new EventQuery(query));
// times out watcher.WaitForNextEvent in 5 seconds
watcher.Options.Timeout = new TimeSpan(0,0,5);
// 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"""
' Initialize an event watcher and subscribe to events
' that match this query
Dim watcher As New ManagementEventWatcher( _
New ManagementScope("root\CIMV2"), _
New EventQuery(query))
' times watcher.WaitForNextEvent in 5 seconds
watcher.Options.Timeout = New TimeSpan(0, 0, 5)
' 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
ManagementEventWatcher(String, String)
- Source:
- ManagementEventWatcher.cs
- Source:
- ManagementEventWatcher.cs
- Source:
- ManagementEventWatcher.cs
Initializes a new instance of the ManagementEventWatcher class that listens for events conforming to the given WMI event query. For this variant, the query and the scope are specified as strings.
public:
ManagementEventWatcher(System::String ^ scope, System::String ^ query);
public ManagementEventWatcher (string scope, string query);
new System.Management.ManagementEventWatcher : string * string -> System.Management.ManagementEventWatcher
Public Sub New (scope As String, query As String)
Parameters
- scope
- String
The management scope (namespace) in which the watcher will listen for events.
- query
- String
The query that defines the events for which the watcher will listen.
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\"";
// Initialize an event watcher and subscribe to events
// that match this query
ManagementEventWatcher watcher =
new ManagementEventWatcher("root\\CIMV2",
query);
// times out watcher.WaitForNextEvent in 5 seconds
watcher.Options.Timeout = new TimeSpan(0,0,5);
// 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"""
' Initialize an event watcher and subscribe to events
' that match this query
Dim watcher As New ManagementEventWatcher( _
"root\CIMV2", query)
' times watcher.WaitForNextEvent in 5 seconds
watcher.Options.Timeout = New TimeSpan(0, 0, 5)
' 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
ManagementEventWatcher(ManagementScope, EventQuery, EventWatcherOptions)
- Source:
- ManagementEventWatcher.cs
- Source:
- ManagementEventWatcher.cs
- Source:
- ManagementEventWatcher.cs
Initializes a new instance of the ManagementEventWatcher class that listens for events conforming to the given WMI event query, according to the specified options. For this variant, the query and the scope are specified objects. The options object can specify options such as time-out and context information.
public:
ManagementEventWatcher(System::Management::ManagementScope ^ scope, System::Management::EventQuery ^ query, System::Management::EventWatcherOptions ^ options);
public ManagementEventWatcher (System.Management.ManagementScope scope, System.Management.EventQuery query, System.Management.EventWatcherOptions options);
new System.Management.ManagementEventWatcher : System.Management.ManagementScope * System.Management.EventQuery * System.Management.EventWatcherOptions -> System.Management.ManagementEventWatcher
Public Sub New (scope As ManagementScope, query As EventQuery, options As EventWatcherOptions)
Parameters
- scope
- ManagementScope
A ManagementScope representing the scope (namespace) in which the watcher will listen for events.
- query
- EventQuery
An EventQuery representing a WMI event query, which determines the events for which the watcher will listen.
- options
- EventWatcherOptions
An EventWatcherOptions representing additional options used to watch for events.
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, so wait for 1 event to return
EventWatcherOptions options = new EventWatcherOptions(
null, TimeSpan.MaxValue, 1);
// Initialize an event watcher and subscribe to events
// that match this query
ManagementEventWatcher watcher =
new ManagementEventWatcher(
new ManagementScope("root\\CIMV2"),
new EventQuery(query), options);
// 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, so wait for 1 event to return
Dim options As New EventWatcherOptions( _
Nothing, TimeSpan.MaxValue, 1)
' Initialize an event watcher and subscribe to events
' that match this query
Dim watcher As New ManagementEventWatcher( _
New ManagementScope("root\CIMV2"), _
New EventQuery(query), _
options)
' 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
ManagementEventWatcher(String, String, EventWatcherOptions)
- Source:
- ManagementEventWatcher.cs
- Source:
- ManagementEventWatcher.cs
- Source:
- ManagementEventWatcher.cs
Initializes a new instance of the ManagementEventWatcher class that listens for events conforming to the given WMI event query, according to the specified options. For this variant, the query and the scope are specified as strings. The options object can specify options such as a time-out and context information.
public:
ManagementEventWatcher(System::String ^ scope, System::String ^ query, System::Management::EventWatcherOptions ^ options);
public ManagementEventWatcher (string scope, string query, System.Management.EventWatcherOptions options);
new System.Management.ManagementEventWatcher : string * string * System.Management.EventWatcherOptions -> System.Management.ManagementEventWatcher
Public Sub New (scope As String, query As String, options As EventWatcherOptions)
Parameters
- scope
- String
The management scope (namespace) in which the watcher will listen for events.
- query
- String
The query that defines the events for which the watcher will listen.
- options
- EventWatcherOptions
An EventWatcherOptions representing additional options used to watch for events.
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, so wait for 1 event to return
EventWatcherOptions options = new EventWatcherOptions(
null, TimeSpan.MaxValue, 1);
// Initialize an event watcher and subscribe to events
// that match this query
ManagementEventWatcher watcher =
new ManagementEventWatcher(
new ManagementScope("root\\CIMV2"),
new EventQuery(query), options);
// 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, so wait for 1 event to return
Dim options As New EventWatcherOptions( _
Nothing, TimeSpan.MaxValue, 1)
' Initialize an event watcher and subscribe to events
' that match this query
Dim watcher As New ManagementEventWatcher( _
"root\CIMV2", _
query, _
options)
' 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
.NET