Why not OpenSearch?
OpenSearch is very cool and we like it a lot. But it is a search protocol, not a known item retrieval protocol. If you know that a webapp has information about urn:isbn:123456789X, and search that value through an OpenSearch interface for that webapp, you just don’t know what you’ll get… maybe there will be sixteen “search hits” that reference that object somehow. Or maybe the site won’t actually index identifiers like that so even though you know the site carries information about that book, you might not be able to find it through a search interface.unAPI addresses this problem by providing an HTML microformat for indicating exactly when information about an item is available through the unAPI interface, and a simple pair of functions for interacting with that known item through the unAPI interface. You know exactly what you’ll get.
