Self-updating site

I want to make a site that updates itsel开发者_JAVA技巧f based upon changes on another site. For example, every time certain external site posts an article with a specific tag, my site should update and post a notice reporting that.

What tools would you recommend for doing such task?

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I'd use RSS or JSON on the first site and make a feed of all the changes. If I can't do that due to ownership, I'd just parse the site with BeautifulSoup and cron every few minutes to record changes via that.

I'd run the second site using the Flask web framework and Python, as it's easy for me to churn out things quickly with Python.

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You could also implement Pubsubhubbub for near-realtime notifications. It's based on Atom.