namespace SoftwareArchitects.Web
{
  public class CachingHandler : IHttpHandler
  {
    public bool IsReusable
    {
      get { return true; }
    }
  
    public void Proce***equest(HttpContext context)
    {
      string file = context.Server.MapPath
        (context.Request.FilePath.Replace(".ashx", ""));
      string filename = file.Substring(file.LastIndexOf('\\') + 1);
      string extension = file.Substring(file.LastIndexOf('.') + 1);
      CachingSection config = (CachingSection)context.GetSection
        ("SoftwareArchitects/Caching");
      if (config != null)
      {
        context.Response.Cache.SetExpires
          (DateTime.Now.Add(config.CachingTimeSpan));
        context.Response.Cache.SetCacheability
            (HttpCacheability.Public);
        context.Response.Cache.SetValidUntilExpires(false);

          FileExtension fileExtension = config.FileExtensions[extension];
        if (fileExtension != null)
       {
          context.Response.ContentType = fileExtension.ContentType;
       }
     }
    context.Response.AddHeader("content-disposition",
    "inline; filename=" + filename);
    context.Response.WriteFile(file);
    }
  }
}

namespace SoftwareArchitects.Web.Configuration
{
  /// <summary>
  /// Configuration for caching
  /// </summary>
  public class CachingSection : ConfigurationSection
  {
    [ConfigurationProperty("CachingTimeSpan", IsRequired = true)]
    public TimeSpan CachingTimeSpan
    {
      get { return (TimeSpan)base["CachingTimeSpan"]; }
      set { base["CachingTimeSpan"] = value; }
    }

    [ConfigurationProperty("FileExtensions", IsDefaultCollection = true,
      IsRequired = true)]
    public FileExtensionCollection FileExtensions
    {
      get { return ((FileExtensionCollection)base["FileExtensions"]); }
    }
  }
/// <summary>
  /// List of available file extensions
  /// </summary>
  public class FileExtensionCollection : ConfigurationElementCollection
  {
    ...
  }
/// <summary>
  /// Configuration for a file extension
  /// </summary>
  public class FileExtension : ConfigurationElement
  {
    [ConfigurationProperty("Extension", IsRequired = true)]
    public string Extension
    {
      get { return (string)base["Extension"]; }
      set { base["Extension"] = value.Replace(".", ""); }
    }
  
    [ConfigurationProperty("ContentType", IsRequired = true)]
    public string ContentType
    {
      get { return (string)base["ContentType"]; }
      set { base["ContentType"] = value; }
    }
  }
}

<configuration>
  <configSections>
    <sectionGroup name="SoftwareArchitects">
      <section name="Caching" requirePermission="false"
        type="SoftwareArchitects.Web.Configuration.CachingSection,
        SoftwareArchitects.Web.CachingHandler" />
    </sectionGroup>
  </configSections>

<SoftwareArchitects>
    <Caching CachingTimeSpan="1">
      <FileExtensions>
        <add Extension="gif" ContentType="p_w_picpath\gif" />
        <add Extension="jpg" ContentType="p_w_picpath\jpeg" />
        <add Extension="png" ContentType="p_w_picpath\png" />
      </FileExtensions>
    </Caching>
  </SoftwareArchitects>

...
<httpHandlers>
    <add verb="*" path="*.gif.ashx"
      type="SoftwareArchitects.Web.CachingHandler,
      SoftwareArchitects.Web.CachingHandler"/>
    <add verb="*" path="*.jpg.ashx"
      type="SoftwareArchitects.Web.CachingHandler,
      SoftwareArchitects.Web.CachingHandler"/>
    <add verb="*" path="*.png.ashx"
      type="SoftwareArchitects.Web.CachingHandler,
      SoftwareArchitects.Web.CachingHandler"/>
  </httpHandlers>
</configuration>