EventWatcherOptions Class


Specifies options for management event watching.

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


public class EventWatcherOptions : ManagementOptions


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

System_CAPS_pubmethodEventWatcherOptions(ManagementNamedValueCollection, TimeSpan, Int32)

Initializes a new instance of the EventWatcherOptions class with the given values.


Gets or sets the block size for block operations. When waiting for events, this value specifies how many events to wait for before returning.


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.)


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.)


Returns a copy of the object. (Overrides ManagementOptions.Clone().)


Determines whether the specified object is equal to the current object.(Inherited from Object.)


Allows an object to try to free resources and perform other cleanup operations before it is reclaimed by garbage collection.(Inherited from Object.)


Serves as the default hash function. (Inherited from Object.)


Gets the Type of the current instance.(Inherited from Object.)


Creates a shallow copy of the current Object.(Inherited from Object.)


Returns a string that represents the current object.(Inherited from Object.)

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.

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
        eventOptions.Timeout = System.TimeSpan.MaxValue;

        // Initialize an event watcher and subscribe to events 
        // that match this query
        ManagementEventWatcher watcher =
            new ManagementEventWatcher("root\\CIMV2", query,

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

        //Display information from the event
            "Process {0} has been created, path is: {1}", 

        //Cancel the subscription
        return 0;

.NET Framework
Available since 1.1

Any public static (Shared in Visual Basic) members of this type are thread safe. Any instance members are not guaranteed to be thread safe.

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