private void LogTrace(string level, string s)
        {
            if (!TraceEnabled)
            {
                return;
            }

            lock (Trace)
            {
                Trace.Append(DateTime.UtcNow.ToString("yyyy-MM-dd HH:mm:ss"));
                Trace.Append(" ");
                Trace.Append(level);
                Trace.Append(" ");
                Trace.AppendLine(s);
            }
        }