Some of the most powerful and versatile ColdFusion application event handlers are often the most ignored: the onRequest event handlers. Not sure why these so often seem to get ignored, but I can't name for you how many times, and how many apps, I've started working on that weren't using any of these methods in any capacity, and needed to.
Like the onApplication and onSession before it, the onRequest event handlers include methods that fire immediately before (onRequestStart) and after (onRequestEnd) the page request. Also like the scopes of those handlers, the onRequest handlers allow access to the REQUEST scope variables without having to lock access to those variables. Those are pretty standard, and not much to figure out. But the onRequest handlers also include two additional handlers: onRequest, and onCFCRequest. These two are a bit more confusing to understand "why?", so we'll go a little more in depth.