Nowadays responsive, user-friendly websites are the norm and no longer the exception. Thanks to using AJAX for partial page updates and real-time updates users don’t need to wait for the browser to finish its communication with the server after every action – they are free to open new messages, accept friend requests or browse image galleries while the browser works in the background. One operation though often needs to block the user interaction while it completes – file uploading. As always Telerik is here to help in this tough situation – meet the RadAsyncUpload.


In its essence RadAsyncUpload lets the user start a file upload without doing a full postback so they can continue working with the page. We modeled the API and the looks of RadAsyncUpload as close as possible to the RadUpload to facilitate eventual migration, but due to the nature of asynchronous file uploads there are some important differences.

When RadAsyncUpload uploads files, it saves them to a temporary folder defined by the TemporaryFolder property until the page is submitted. Once a postback occurs RadAsyncUpload raises the FileUploaded event for each temporary file so handlers attached to the event can process the files and eventually save them to a destination folder.

Another difference is that the RadAsyncUpload requires the Telerik.Web.UI.WebResource HttpHandler to be registered in the web.config, but this is already done if you are using RadScriptManager

This is just a beta version with the main features included. We are already working on some great user experience improvements like less clicking when you need to add another file and much less hassle when you need to upload multiple files at once, but the details deserve another blog post once these improvements arrive.

About the Author

Iana Tsolova

is Product Manager at Telerik’s DevTools division. She joined the company back in the beginning of 2008 as a Support Officer and has since occupied various positions at Telerik, including Senior Support Officer, Team Lead at one of the ASP.NET AJAX teams and Technical Support Director. Iana’s main interests are web development, reading articles related to geography, wild nature and latest renewable energy technologies.

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