APICache allows any API client library to be easily wrapped with a robust caching layer. It supports caching (obviously), serving stale data and limits on the number of API calls. It’s also got a handy syntax if all you want to do is cache a bothersome url.
$ sudo gem install api_cache -s http://gemcutter.org
This is how you access the twitter public timeline if you need your site to stay up, regardless of what twitter does.
require 'rubygems' require 'api_cache' APICache.get("http://twitter.com/statuses/public_timeline.rss")
It will fetch a new version once the cached version is 10 minutes old, keep the old version for a day just in case, and never contact twitter more than once a minute. Of course all these numbers are configurable.
APICache uses moneta so you can use any key-value store you like.
require 'moneta/memcache' APICache.store = Moneta::Memcache.new(:server => "localhost")
This adds caching to an otherwise excellent Flickr library.
APICache.get("my_photos") do SuperFlickLibWhichDoesntDoCaching.get_my_photos end
See the README for a proper introduction.