Create Single Use URIs to Protect Your Resources!

Finding the problem, of controlling access to specific resources for a certain amount of time and for a certain amount of downloads, to be quite interesting. So I decided to design a solution that would take advantage of the services made available by the Windows Azure platform.

The Challenge

Create single use URIs that invalidate after 15 minutes.

Why?

Companies that sell digital products often try to limit the number of downloads per purchase. Consequently, discouraging customers from sharing their download links becomes a priority. By creating public URIs constrained by a time to live and by a limited number downloads, can help accomplish this goal.

The Concept

Building on the Valet Key Pattern explored in “Keep Your Privates Private!” I used Shared Access Signatures to create a time to live for all public URIs. Then to control access to the actual resources I created a REST service using Web API, which tracks individual access to each URI using the Windows Azure Table Storage Service.

Why Are WebRequests Throttled? I Want More Throughput!

By default, a web browser – or in this case any .Net application that uses the System.Net.WebRequest class – will only allow up to 2 simultaneous threads at a time per host domain.

One way to lift this limit is to run Fiddler. It bypasses this limit and you can see much more throughput. I admit that this is a hack but it works when debugging.

When your code is running inside Windows Azure, Fiddler isn’t a possible hack, but wait there’s a better way!

Add the following configuration to your App.Config or Web.Config.