ASP.NET

public class ResponseSizeHttpModule : IHttpModule
   {

       public void Init(HttpApplication application)
       {
           if (Convert.ToBoolean(ConfigurationManager.AppSettings["CheckResponseSize"]) == true)
           {
               application.BeginRequest += new EventHandler(this.AddFilter);
               application.EndRequest += new EventHandler(this.ResponseMessage);
           }
       }

       private void AddFilter(Object source, EventArgs e)
       {
           HttpApplication application = (HttpApplication)source;
           application.Response.Filter = new CounterClass(application.Response.Filter);
       }

       private void ResponseMessage(Object source, EventArgs e)
       {
           HttpApplication application = (HttpApplication)source;
           long lPageSize = application.Response.Filter.Length;
           long lRespLimit = Convert.ToInt64(ConfigurationManager.AppSettings["ResponseLimitBytes"]);

           if (lPageSize > lRespLimit)
           {
               string strResponse = ""; //get the content of the response here!
               int intNumIncludes = CountIncludes(strResponse);
               //StringBuilder sbAlertMsg = new StringBuilder();
               //build message here
               //HttpContext.Current.Response.Write(sbAlertMsg);
           }
       }

       private int CountIncludes(string strResponse)
       {
           Regex reScripts = new Regex(".js|.css", RegexOptions.IgnoreCase);

           return reScripts.Matches(strResponse).Count;
       }

       public void Dispose(){}
   }