/// <summary>
/// Summary description for ResponseFilter.
/// </summary>
public partial class ResponseFilter : System.Web.UI.Page
{
   protected System.Web.UI.HtmlControls.HtmlForm Form1;
   protected System.Web.UI.WebControls.TextBox TextBox1;
 
   protected void Page_Load(object sender, System.EventArgs e)
   {
      // Put user code to initialize the page here
         if (this.chkEnableFilter.Checked)
             Response.Filter = new UpperCaseFilter(Response.Filter);
         else
         {
             // We have to redirect to get back to non-encoded page
             if (IsPostBack)
                 Response.Redirect("ResponseFilter.aspx");
         }
   }
 
 
}
 
 
 public class UpperCaseFilter : Stream
 // This filter changes all characters passed through it to uppercase.
 {
     private Stream _stream;
     private long _position;
 
     public UpperCaseFilter(Stream sink)
     {
         _stream = sink;
     }
 
     // The following members of Stream must be overriden.
     public override bool CanRead
     {
         get { return true; }
     }
 
     public override bool CanSeek
     {
         get { return true; }
     }
 
     public override bool CanWrite
     {
         get { return true; }
     }
 
     public override long Length
     {
         get { return 0; }
     }
 
     public override long Position
     {
         get { return _position; }
         set { _position = value; }
     }
 
     public override long Seek(long offset, System.IO.SeekOrigin direction)
     {
         return _stream.Seek(offset, direction);
     }
 
     public override void SetLength(long length)
     {
         _stream.SetLength(length);
     }
 
     public override void Close()
     {
         _stream.Close();
     }
 
     public override void Flush()
     {
         ms = TransformStream(ms);
         _stream.Write(ms.ToArray(), 0, (int)ms.Length);
 
         _stream.Flush();
     }
 
     public override int Read(byte[] buffer, int offset, int count)
     {
         return _stream.Read(buffer, offset, count);
     }
 
     MemoryStream ms = new MemoryStream(5000);
     int buffPointer = 0;
 
     // The Write method actually does the filtering.
     public override void Write(byte[] buffer, int offset, int count)
     {       
         // copy to holding buffer
         ms.Write(buffer,0, count);
         buffPointer += count;
 
        // _stream.Write(buffer, 0, count);
     }
 
     protected MemoryStream TransformStream(MemoryStream ms)
     {
         string text = Encoding.Default.GetString(ms.ToArray());
 
         text = text.Replace("the", "THE BIG REPLACEMENT CAPER");
 
         return new MemoryStream(Encoding.Default.GetBytes(text));            
     }
 }