Alternating Least Squares

  User ID
/recommend /

  Item ID 1  (Item ID 2)
/recommendToAnonymous / /

  Item ID 1  (Item ID 2)
/similarity / /

  To Item  Item ID
/similarityToItem / /

  User ID  Item ID
/estimate / /

  User ID  Item ID
/because / /

  User ID
/mostSurprising /

/mostPopularItems

/mostActiveUsers

/popularRepresentativeItems

/item/allIDs

/user/allIDs

  User ID
/knownItems /

  User ID  Item ID
/pref / /

/ingest

/ingest
[]