The following message appears e.g. when downloading a stream:

XMLHttpRequest cannot load HYPERLINK "http://...:8080/.../$value"
No 'Access-Control-Allow-Origin' header is present on the requested resource. Origin 'HYPERLINK "http://localhost'%20is%20therefore%20not%20allowed%20access/"http://localhost' is therefore not allowed access


You have to add the "Access-Control-Allow-Origin" header attribute to the response. To to this paste the following into your download functionality:

WebOperationContext.Current.OutgoingResponse.Headers.Add("Access-Control-Allow-Origin", "*");