Registry Watcher C#

Question

I'm a newbie to WMI and I need to implement RegistryValueChangeEvent in a C# service.

I need an event handler that gets triggered each time any one of a set of registry values is changed. I want behavior similar to the FileSystemWatcher class's Changed event, but for registry values.

If there's some other technique I could use to accomplish the same task, I'd appreciate that as well. My minimum requirement is that it be a better solution than what I have now: polling every 20 seconds and comparing the registry value with the last result.

Please provide example code in your answer. If I can get an example for watching just one registry value, that would be fine.

I need a solution in .Net 2.0

Thanks.

Answer 1

WMI can sometimes be interesting to work with...I think I understand your question, so take a look at the code snippet below and let me know if it's what you're looking for.

// ---------------------------------------------------------------------------------------------------------------------  // <copyright file="Program.cs" company=""> //    // </copyright> // <summary> //   Defines the WmiChangeEventTester type. // </summary> // --------------------------------------------------------------------------------------------------------------------- namespace WmiExample {     using System;     using System.Management;      /// <summary>     /// </summary>     public class WmiChangeEventTester     {         /// <summary>         /// Initializes a new instance of the <see cref="WmiChangeEventTester"/> class.         /// </summary>         public WmiChangeEventTester()         {             try             {                 // Your query goes below; "KeyPath" is the key in the registry that you                 // want to monitor for changes. Make sure you escape the \ character.                 WqlEventQuery query = new WqlEventQuery(                      "SELECT * FROM RegistryValueChangeEvent WHERE " +                      "Hive = 'HKEY_LOCAL_MACHINE'" +                      @"AND KeyPath = 'SOFTWARE\\Microsoft\\.NETFramework' AND ValueName='InstallRoot'");                  ManagementEventWatcher watcher = new ManagementEventWatcher(query);                 Console.WriteLine("Waiting for an event...");                  // Set up the delegate that will handle the change event.                 watcher.EventArrived += new EventArrivedEventHandler(HandleEvent);                  // Start listening for events.                 watcher.Start();                  // Do something while waiting for events. In your application,                 // this would just be continuing business as usual.                 System.Threading.Thread.Sleep(100000000);                  // Stop listening for events.                 watcher.Stop();             }             catch (ManagementException managementException)             {                 Console.WriteLine("An error occurred: " + managementException.Message);             }         }          /// <summary>         /// </summary>         /// <param name="sender">         /// The sender.         /// </param>         /// <param name="e">         /// The e.         /// </param>         private void HandleEvent(object sender, EventArrivedEventArgs e)         {             Console.WriteLine("Received an event.");             // RegistryKeyChangeEvent occurs here; do something.         }          /// <summary>         /// </summary>         public static void Main()         {             // Just calls the class above to check for events...             WmiChangeEventTester receiveEvent = new WmiChangeEventTester();         }     } } 

Answer 2

Are you limited to WMI? If not you can use RegNotifyChangeKeyValue wrappers like RegistryMonitor