public double getTotalResponseTime()
    {
        if (exitTimes_ == null || entryTimes_ == null) {
            return 0;
        }

        double time = 0;
        try
        {
            double startTime = ((Double)exitTimes_.firstElement()).doubleValue();
            double receiveTime = ((Double)entryTimes_.lastElement()).doubleValue();
            time = receiveTime - startTime;
        }
        catch(Exception e) {
            time = 0;
        }

        return time;
    }