Architectural approach to HTTP routing pioneered by Roda and adopted (with a ground-up reimplementation) by Yippee. Instead of parsing a routes file at boot into a state-machine tree that every request matches against (as in Rails), a routing tree executes ordinary code paths — HTTP requests walk down a tree of controller methods / nested controllers until a handler responds. Consequence: boot time is constant regardless of route count (10 vs 10,000,000 routes cost the same at start-up), at the cost of doing matching work per request. Yippee targets single-digit-millisecond boot and supports hash-based shortcut dispatch at hot nodes for near-O(1) request matching when needed.