Combined RSS feed generation from multiple source feeds

I need a web application that will create a valid RSS 2.0 feed with enclosures from multiple source feeds. The application should: * provide an interface to input the source feeds into a MySQL database * read those feeds using a standard library (for example, if usingg php something like SimplePie RSS or MagPie RSS) * be started by a cron job at pre-determined times * compare items in the source feeds with items already processed previously * create a static RSS feed file with source feed posts in chronological order, without duplicates. The application with take all necessary and appropriate security precautions to prevent intrusion/XSS.