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WebForms AsyncUpload Overview

Select files to upload (.jpeg,.jpg,.png,.doc,.docx,.xls,.xlsx)



Hi John,

Please find the new agency design proposals attached.

Let me know what you think.




  • Press the select button to trigger the file dialog or drop some files over the control in order to start uploading.
  • Select a few files at the same time to make use of the multi-file selection functionality.
  • Enjoy the neat progress bar that shows next to each file being uploaded.
  • Try uploading an invalid file (an executable file, for example) to test out the automatic validation.

About RadAsyncUpload for ASP.NET AJAX

Perform configurable asynchronous uploads of single or multiple files using RadAsyncUpload for ASP.NET AJAX. The control addresses the limitation to perform file uploads with plain post backs only, and supports web farm scenarios, as well as internal validation, using its http handler for this purpose. RadAsyncUpload provides smooth file async upload handling with rich progress status information display, and its efficient proprietary http handler allocates minimum server memory while providing security features.

RadAsyncUpload and 120+ other controls are part of UI for ASP.NET AJAX, a comprehensive toolset taking care of the common functionality of your application, while leaving you with more time to work on its business logic.

Key Features

  • Fully asynchronous file upload
  • Out of the box progress monitoring
  • Built-in validation
  • Visual indicators for common operations
  • Support for drag and drop file upload
  • Allows the upload of large files over 4MB

More about RadAsyncUpload for ASP.NET AJAX
  • DefaultVB.aspx
  • DefaultVB.aspx.vb
  • styles.css
<%@ Page Language="VB" AutoEventWireup="false" CodeFile="DefaultVB.aspx.vb" Inherits="AsyncUpload.Examples.Overview.DefaultVB" %>

<%@ Register TagPrefix="telerik" Namespace="Telerik.Web.UI" Assembly="Telerik.Web.UI" %>
<!DOCTYPE html>
<html xmlns=''>
<head runat="server">
    <title>Telerik ASP.NET Example</title>
    <link rel="stylesheet" type="text/css" href="styles.css" />

    <form id="form1" runat="server">
    <telerik:RadScriptManager runat="server" ID="RadScriptManager1" />
    <telerik:RadSkinManager ID="RadSkinManager1" runat="server" ShowChooser="true" />
    <div class="demo-container size-wide">
        <div class="header-container"></div>
        <div class="attachment-container">
            <telerik:RadAsyncUpload RenderMode="Lightweight" runat="server" CssClass="async-attachment" ID="AsyncUpload1"
                AllowedFileExtensions=".jpeg,.jpg,.png,.doc,.docx,.xls,.xlsx" />
            <span class="allowed-attachments">Select files to upload <span class="allowed-attachments-list">(<%= String.Join( ",", AsyncUpload1.AllowedFileExtensions ) %>)</span>
        <div class="text-boxes-container">
            <p class="text-box">To</p>
            <p class="text-box">Subject</p>
            <div class="writing-box">
                <p>Hi John,</p>
                <br />  
                <p>Please find the new agency design proposals attached.</p>
                <p>Let me know what you think.</p>
                <br />
                <br />  

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