Hello Midav Obuarez,
The RadUpload control is only capable of uploading files from the Silverlight client application to the server. If you want to be able to return the data back to the cilent, you would have to use a different data channel - for example WCF service. I am not sure you will be able to reuse the RadUploadHandler to implement donwload.
Data chunking depends on the size of the data that you are going to transfer. If you expect large data, then it is definitely better to use chunks and transfer the data a chunk at a time.
the Telerik team
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