title: scraping a non RSS page to generate a feed
body: <p>I want to scrape a page that regularly updates (adding new articles with exactly the same structure as previous ones) in order to generate an RSS feed. </p>
  
  <p>I can write the code to analyse the page easily, but how do I emulate a ping i.e. when the page updates how can my php script know? Does it have to be a cron job?</p>
  
  <p>(Probably a duplicate question I know, but searched for a direct answer with no luck. Closest I got was <a href="https://stackoverflow.com/questions/557598/scrape-and-generate-rss-feed">Scrape and generate RSS feed</a>, which has a scraping script but no info on how to get it to respond to changes on the page automatically)</p>