Question

I’m thinking of adding some code to my global.asax to my web apps to email me when there is an unhandled exception.

Current, I’m doing the following

• Writing a cookie on the user’s machine – in case they spam hit F5 and the website was restarted
• Adding an entry into system.Web.Cache –

Am I missing something? Would you do something different?

protected void Application_Error()
{
    var ex = Server.GetLastError();
    Server.ClearError();

    if (NotInCache(ex))
    {
        // Email support
    }
}



private static bool NotInCache(Exception ex)
{
    bool returnValue = true;

        if (ex != null)
        {
            HttpContext current = HttpContext.Current;
            LogWriter.Trace(MethodBase.GetCurrentMethod(), Dfait.Diagnostics.TraceLevel.Level4, "Checking Cache for our exception");

            if (current != null)
            {
                string key = ex.StackTrace;
                string[] split = System.Text.RegularExpressions.Regex.Split(ex.StackTrace, "\r\n");
                string value = "Exception Exists";
                DateTime expiryDate = DateTime.Now.AddDays(1);

                if (split.Length > 0)
                {
                    key = split[0];
                }

                key = key.Trim();

                HttpCookie remedyCookie = current.Request.Cookies[key];

                if (remedyCookie == null)
                {
                    HttpCookie newCookie = new HttpCookie(key, value);
                    newCookie.Expires = expiryDate;
                    current.Response.Cookies.Add(newCookie);
                }
                else
                {
                    returnValue = false;
                }

                // The next block is to check the cache of the user.
                object foundCache = HttpRuntime.Cache[key];

                if (foundCache == null)
                {
                    HttpRuntime.Cache.Insert(key, value, null, expiryDate, TimeSpan.Zero);
                }
                else
                {
                    returnValue = false;
                }
            }
        }

    return returnValue;
}

Answer 1

Depending on how soon you want the exceptions you could always just log them to a file and then email the file to yourself every 10 minutes, 1 hour, 1 day and etc.

That way you don’t need to worry to much about if people spam the website as it will just be a bunch of duplicate exceptions in the file.

Once you send the file you could delete it or some how mark it as sent and then start a new file that way you only get a file emailed once there is something new to be sent.