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Old August 25th, 2003, 02:24 PM
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Default File size on customer side

Hi all,
I'm looking for a solution for the following problem.

A customer logs in to the webserver and see a list with requested file where he payed for. Once the download was sucesfull he cannot download the file a 2th time.

Any idea how to solve this practical ?


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Old August 25th, 2003, 03:36 PM
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This is a tough one for a couple reasons. I don't know if there is a reliable way to provide only single access thru client-side code. If the person refreshed the page, they would be able to "reset" the lockout. Normally, this kind of thing would be accomplished by keeping track of when the file has been downloaded on the server side. Usually, you'd provide a link to a page that returned a binary stream of the desired file instead of providing a link directly to the file. (a direct link would of course not secure it from being downloaded twice.) However, one then encounters the issue of a failed download. If you mark the file as "downloaded for user x" and their download breaks halfway thru then you have a problem. Not sure how people solve this issue. Perhaps someone else has a suggestion.

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Old August 25th, 2003, 04:16 PM
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I posted a suggestion in another forum, suggesting to stream the file as well, after the database has been checked for sufficient permissions to download it again.

One solution to overcome the failed download is to set a flag in the database after the file has been completed. I think the BinaryWrite method (which you use to stream the file) is a blocking call; that is, the function will be performed on the main thread, blocking other code following it. If the line directly after the BinaryWrite performs a database update, you can be pretty sure that once you do the update, you have a valid download.

(See Vincent, cross-posting causes more problems than it solves. Now the questions and answers are all over the place, forcing everyone to follow a couple of threads and do cross-referencing all the time.... ;))


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