Export (0) Print
Expand All

EventWatcherOptions Class

Specifies options for management event watching.

System.Object
  System.Management.ManagementOptions
    System.Management.EventWatcherOptions

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

public class EventWatcherOptions : ManagementOptions

The EventWatcherOptions type exposes the following members.

  NameDescription
Public methodEventWatcherOptions()Initializes a new instance of the EventWatcherOptions class for event watching, using default values. This is the default constructor.
Public methodEventWatcherOptions(ManagementNamedValueCollection, TimeSpan, Int32)Initializes a new instance of the EventWatcherOptions class with the given values.
Top

  NameDescription
Public propertyBlockSizeGets or sets the block size for block operations. When waiting for events, this value specifies how many events to wait for before returning.
Public propertyContextGets 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.)
Public propertyTimeoutGets 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.)
Top

  NameDescription
Public methodCloneReturns a copy of the object. (Overrides ManagementOptions.Clone().)
Public methodEquals(Object)Determines whether the specified object is equal to the current object. (Inherited from Object.)
Protected methodFinalizeAllows an object to try to free resources and perform other cleanup operations before it is reclaimed by garbage collection. (Inherited from Object.)
Public methodGetHashCodeServes as the default hash function. (Inherited from Object.)
Public methodGetTypeGets the Type of the current instance. (Inherited from Object.)
Protected methodMemberwiseCloneCreates a shallow copy of the current Object. (Inherited from Object.)
Public methodToStringReturns a string that represents the current object. (Inherited from Object.)
Top

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
            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;
    }
}

.NET Framework

Supported in: 4.6, 4.5, 4, 3.5, 3.0, 2.0, 1.1, 1.0

.NET Framework Client Profile

Supported in: 4, 3.5 SP1

Windows 8.1, Windows Server 2012 R2, Windows 8, Windows Server 2012, Windows 7, Windows Vista SP2, Windows Server 2008 (Server Core Role not supported), Windows Server 2008 R2 (Server Core Role supported with SP1 or later; Itanium not supported)

The .NET Framework does not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.

Any public static (Shared in Visual Basic) members of this type are thread safe. Any instance members are not guaranteed to be thread safe.
Show:
© 2014 Microsoft