Michael's Blog

As I know there are a lot of developers that do not have a internet server with full access to the IIS (f.e. using a administrator website or remote desktop). You have to change the IIS settings for the new file extension.

Yesterday I found a good solution on how to use a special file extension without changing IIS settings or to put settings in the web.config.

After the .NET installation you will find some file extensions already in the list. One of them will be .ASHX (ASP.NET Handler). In this file you have to write the class where you have put your IHttpHandler:

As you can see in the above sample you can use codebehind like in webforms or webservices.

My IHttpHandler sample application will allow you to use a similar technic like the new .ASIX file extension in Microsoft .NET 2.0 (beta).

using System;
using System.Drawing;
using System.Drawing.Drawing2D;
using System.Web;
namespace WebApplication1
{
  public delegate void RenderEventHandler(Graphics g, System.EventArgs e);

  public class MyHttpHandler : IHttpHandler
  {
    public event RenderEventHandler Render;
    protected int Width = 100;
    protected int Height = 100;

    public MyHttpHandler()
    {
      OnInit(new EventArgs());
    }

    protected virtual void OnInit(EventArgs e)
    {}

    public void ProcessRequest(HttpContext context)
    {
      Bitmap bmp = new Bitmap(Width, Height);
      Graphics g = Graphics.FromImage(bmp);
      g.FillRectangle(new SolidBrush(Color.White), 0, 0, bmp.Width, bmp.Height);

      if(Render != null)
      {
        Render(g, new EventArgs());
      }

      bmp.Save(context.Response.OutputStream, System.Drawing.Imaging.ImageFormat.Jpeg);
      g.Dispose();
      bmp.Dispose();
      g =  null;
      bmp = null;
    }

    public bool IsReusable
    {
      get{ return false; }
    }
  }
}

Now, you can draw a image directly in your codebehind file. As you can see in the following codebehind file for the .ASHX you have a Render event that will be called from the IHttpHandler.

using System;
using System.Drawing;
using System.Web;
namespace WebApplication1
{
  public class MyChart : MyHttpHandler
  {

  private void Page_Render(Graphics g, System.EventArgs e)
  {
    g.DrawLine(new Pen(Color.Black), 0, 0, 100, 100);
  }

  override protected void OnInit(EventArgs e)
  {
    InitializeComponent();
    base.OnInit(e);
  }

  private void InitializeComponent()
  {
    this.Width = 100;
    this.Height = 100;

    this.Render += new RenderEventHandler(this.Page_Render);
  }
}

Based on my article Math Berther has build a second solution on how to use own HttpHandlers:
http://www.mattberther.com/2004/07/000510.html