In this mashup, we used two different web APIs—one from video repository site YouTube, and the XML feeds from social music site Last.fm. We took a look at three different XML-based file formats from those two sites: XSPF for song playlists, RSS for publishing frequently updated information, and YouTube’s custom XML format. We created a mashup that took the songs in two Last.fm feeds and queried YouTube to retrieve videos based on the song.
If we were to create our own XML-based parsers to parse the three formats, this would have taken much more time than it actually did. We found that the PHP Extension and Application Repository, PEAR, already had parsers we could use; one for each of the three formats. Using these PEAR packages, we were able to create an object-oriented abstraction of these formats, which allowed us to easily finish our application.