We have added MVC output caching to our Umbraco site. Each page is cache for some period of time. To prevent stale pages we have tied into the Umbraco ContentService and FileService events to clear the cache.

We are in a load balanced environment using Webserver A and Webserver B to serve content and Admin Server A as the back-end office.

The problem we are having is that when a publish occurs from Admin Server A it is not firing the events to clear the cache on either webserver. The cache is cleared on the Admin server.

Our current work around is to then go to the webserver and publish the content again there. When doing that, both webserver caches clear.

I'm wondering why the Admin Server publish is not triggering the events for the webservers when doing the same thing directly on one of the webservers triggers the event for both web servers.

Here is the code we are using to clear the memory cache:

protected override void ApplicationStarting(UmbracoApplicationBase umbracoApplication, ApplicationContext applicationContext)
    {
        HttpContext.Current.Cache.Insert("CacheControl", DateTime.Now, null,
              DateTime.MaxValue, TimeSpan.Zero,
              System.Web.Caching.CacheItemPriority.NotRemovable,
              null);
        ContentService.Published += HandlePublish;
        ContentService.Deleted += HandleFileChange;
        ContentService.Moved += HandleFileChange;
        FileService.SavedTemplate += HandleFileChange;
        FileService.DeletedTemplate += HandleFileChange;
        FileService.SavedPartialView += HandleFileChange;
        FileService.DeletedPartialView += HandleFileChange;
        base.ApplicationStarting(umbracoApplication, applicationContext);
    }
    private void HandleFileChange(IService sender, EventArgs e)
    {
        ClearCache();
    }
    private void HandlePublish(IPublishingStrategy sender, PublishEventArgs<IContent> e)
    {
        ClearCache();
    }

    private static void ClearCache()
    {
        try
        {
            HttpContext.Current.Cache.Insert("CacheControl", DateTime.Now, null,
                  DateTime.MaxValue, TimeSpan.Zero,
                  System.Web.Caching.CacheItemPriority.NotRemovable,
                  null);
            var cacheManager = new OutputCacheManager();
            cacheManager.RemoveItems();
        }
        catch (Exception e)
        {
            ErrorSignal.FromCurrentContext().Raise(new Exception("Cache failed to clear", e));
        }
    }

Thanks for any assistance.