Every 30 minutes their server generates an XML file with product inside, so my site every half hour would make a request to the URL given to me, their server will generate t
You could simulate a Windows Service using ASP.NET to download and import the XML at scheduled intervals. Otherwise, use a dedicated scheduler like Quartz.NET (already mentioned by Mendy), or build your own Windows Service, or run an import script using Windows Task Scheduler.
http://quartznet.sourceforge.net/
Quartz.NET is a full-featured, open source job scheduling system that can be used from smallest apps to large scale enterprise systems.