Create a cache dependancy on a folder and its sub-folder

In ASP.NET I would like to store an object in the cache which has a dependancy on all the files in specific folder and its sub-folders. Just adding the object with a dependancy on the root folder doesn't work. Is there in any reasonable way to do this other than creating a chain of dependancies on all the files?

From stackoverflow

• I believe you can roll your own cache dependency and use FileSystemMonitor to monitor the filesystem changes.

  Update: Sample code below

  public class FolderCacheDependency : CacheDependency
  {
      public FolderCacheDependency(string dirName)
      {
          FileSystemWatcher watcher = new FileSystemWatcher(dirName);
          watcher.Changed += new FileSystemEventHandler(watcher_Changed);
          watcher.Deleted += new FileSystemEventHandler(watcher_Changed);
          watcher.Created += new FileSystemEventHandler(watcher_Changed);
          watcher.Renamed += new RenamedEventHandler(watcher_Renamed);
      }
  
      void watcher_Renamed(object sender, RenamedEventArgs e)
      {
          this.NotifyDependencyChanged(this, e);
      }
  
      void watcher_Changed(object sender, FileSystemEventArgs e)
      {
          this.NotifyDependencyChanged(this, e);
      }
  }
  

  AnthonyWJones : Does FileSystemWatcher raise events when a file in that directory is changed? FileSystemWatcher watch and entire tree or just the top-level?

  Ramesh : @AnthonyWJones - you can use IncludeSubdirectories to include or exclude them. You may find issues due to multiple events fired. Check out http://msdn.microsoft.com/en-us/library/system.io.filesystemwatcher.aspx