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WebResourceAttribute Class

Defines the metadata attribute that enables an embedded resource in an assembly. This class cannot be inherited.

Namespace:  System.Web.UI
Assembly:  System.Web (in System.Web.dll)

[AttributeUsageAttribute(AttributeTargets.Assembly, AllowMultiple = true)]
[AspNetHostingPermissionAttribute(SecurityAction.LinkDemand, Level = AspNetHostingPermissionLevel.Minimal)]
public sealed class WebResourceAttribute : Attribute

The WebResourceAttribute class is valid only when used on assembly declarations. It is used to enable a specified embedded resource in an assembly for use as a Web resource.

For more information on resources, see ASP.NET Web Page Resources Overview.

This section contains two code examples. The first code example demonstrates how to apply the WebResourceAttribute attribute to a namespace that defines a custom control, MyCustomControl. The second code example demonstrates how to use the MyCustomControl class in a Web page.

The following code example demonstrates how to apply the WebResourceAttribute attribute on a custom assembly to define an image Web resource and an HTML Web resource. The MyCustomControl class defines a composite control that uses the resources to set the value of the ImageUrl property of an Image control that is contained within the composite control and to set the HRef property of an HtmlAnchor control linking to the HTML resource.

using System;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.HtmlControls;
using System.Web.UI.WebControls;

[assembly: WebResource("image1.jpg", "image/jpeg")]
[assembly: WebResource("help.htm", "text/html", PerformSubstitution=true)]
namespace Samples.AspNet.CS.Controls

	public class MyCustomControl : Control

		[System.Security.Permissions.PermissionSet(System.Security.Permissions.SecurityAction.Demand, Name="FullTrust")]
		protected override void CreateChildControls()
			// Create a new Image control.
			Image _img = new Image();
			_img.ImageUrl = this.Page.ClientScript.GetWebResourceUrl(typeof(MyCustomControl), "image1.jpg");

			// Create a new Label control.
			Label _lab = new Label();
			_lab.Text = "A composite control using the WebResourceAttribute class.";

			// Create a new HtmlAnchor control linking to help.htm.
			HtmlAnchor a = new HtmlAnchor();
			a.HRef = this.Page.ClientScript.GetWebResourceUrl(typeof(MyCustomControl), "help.htm");
			a.InnerText = "help link";
			this.Controls.Add(new LiteralControl("<br />"));



The following code example demonstrates how to use the MyCustomControl class in a Web page.

<%@ Page Language="C#" %>
<%@ Register TagPrefix="AspNetSamples" Namespace="Samples.AspNet.CS.Controls" Assembly="Samples.AspNet.CS.Controls" %>
<%@ Import Namespace="System.Reflection" %>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "">

<script runat="server">

  protected void Page_Load(object sender, EventArgs e)

    // Get the assembly metatdata.
    Type clsType = typeof(MyCustomControl);
    Assembly a = clsType.Assembly;

    // Iterate through the attributes for the assembly. 
    foreach (Attribute attr in Attribute.GetCustomAttributes(a))
      //Check for WebResource attributes. 
      if (attr.GetType() == typeof(WebResourceAttribute))
        WebResourceAttribute wra = (WebResourceAttribute)attr;
        Response.Write("Resource in the assembly: " + wra.WebResource.ToString() +
          " with ContentType = " + wra.ContentType.ToString() +
          " and PerformsSubstitution = " + wra.PerformSubstitution.ToString() + "</br>");

<html xmlns="" >
<head runat="server">
    <title>WebResourceAttribute Example</title>
    <form id="form1" runat="server">
      <AspNetSamples:MyCustomControl id="MyCustomControl1" runat="server">

This example requires that you compile the Image1.jpg and Help.htm resources with the assembly that contains MyCustomControl. For more information, see, /resource (Embed Resource File to Output) (C# Compiler Options) or /resource (Visual Basic).

An example of an HTML Web resource that could be used in this example is shown next. Note the use of the WebResource syntax, which is used when you set the PerformSubstitution property to true for a Web resource.

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.1//EN" "">

<html xmlns="" >


<title>Included Help Page</title>




<img alt="help image" src=<% = WebResource("image1.jpg") %> />

Included help file.





Any public static (Shared in Visual Basic) members of this type are thread safe. Any instance members are not guaranteed to be thread safe.

Windows 7, Windows Vista, Windows XP SP2, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP Starter Edition, Windows Server 2008 R2, Windows Server 2008, Windows Server 2003, Windows Server 2000 SP4, Windows Millennium Edition, Windows 98

The .NET Framework and .NET Compact Framework do not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.

.NET Framework

Supported in: 3.5, 3.0, 2.0