File Upload in Ordering System

We wrote an Online Ordering system (ASP.NET, C#, MySQL) for our client, allowing their national customer base to place furniture orders via a portal they could offer their product portfolio through.Recently our client required some additional functionality added to this web application.  We were asked to add a new feature to the ordering process which would supplement the order being placed.For orders of a particular type, our client wanted the customer to upload their furniture plans which would go on to help the warehouse and assembly team, who prepare an order for dispatch.Functions we had to consider:

• As this was a compulsary upload, we had to prevent the order from progressing forward until these plans were uploaded.
• Could a customer have multiple plans, therefore multiple file uploads?
• Storage of these files, and how much space it would consume.  This was dealt with by writing a supplementary Windows Task to regularly clear out the directory into which they were temporarily uploaded.
• The type of file to upload - limiting the expected extensions.
• The total upload size.

This addition function was published with no downtime, and has resulted in additional functionality being planned to further improve their ordering platform.