Response Time Header IHttpModule

ResponseTimeHeaderHttpModule.cs

using System;
using System.Diagnostics;
using System.Web;

public class ResponseTimeHttpModule : IHttpModule
{
    private static readonly String XResponseTimeHeaderName = "X-ResponseTime";

    public void Init(HttpApplication context)
    {
        context.BeginRequest += new EventHandler(BeginRequest);
        context.EndRequest += new EventHandler(EndRequest);
    }

    public void BeginRequest(object sender, EventArgs e)
    {
        try
        {
            if (sender is HttpApplication)
            {
                var httpApplication = (HttpApplication)sender;
                var stopwatch = Stopwatch.StartNew();
                httpApplication.Context.Items.Add(XResponseTimeHeaderName, stopwatch);
            }
        }
        catch
        {
        }
    }

    public void EndRequest(object sender, EventArgs e)
    {
        try
        {
            if (sender is HttpApplication)
            {
                var httpApplication = (HttpApplication)sender;

                if (httpApplication.Context.Items.Contains(XResponseTimeHeaderName))
                {
                    var stopwatch = (Stopwatch)httpApplication.Context.Items[XResponseTimeHeaderName];
                    stopwatch.Stop();
                    var responseTime = Math.Ceiling(stopwatch.Elapsed.TotalMilliseconds);
                    var responseTimeString = String.Format("{0} ms", responseTime);
                    httpApplication.Response.AddHeader(XResponseTimeHeaderName, responseTimeString);
                }
            }
        }
        catch
        {
        }
    }

    public void Dispose()
    {
    }
}