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+ ageOf architecture
+ageOf determines somebody's age by querying one or more sources on the
+Internet. Since there are hundreds of different sites that catalogue the ages
+of famous (and not-so-famous) people, ageOf uses a plugin-based architecture.
+Each source gets its own plugin, and then ageOf queries each source in turn.
+The first source that gives back an age wins.
+The Haskell idiom to do a plugin-based architecture is to define a plugin data
+type, and that's what I've done here. The 'RequestMethod' type represents a
+plugin--a single function that takes the name of a person and returns
+(depending on which constructor you use) his/her age or date of birth. To
+define a new plugin, you thus need to create a new module which exports a
+There are currently two plugins packaged with ageOf (though that may change in
+the future). One is a sample plugin--it knows when Simon Peyton Jones (the
+author of Haskell) was born, and that's it; use it as a skeleton for writing
+your own plugins. The second plugin is a real, nontrivial plugin that uses
+DBpedia (the Semantic Web mirror of Wikipedia) to determine the age of anybody
+whose age is stored on Wikipedia.