Throttling a restful API

Has anyone done anything with iRules/something that would look at the incoming rate of api calls to a restful api endpoint hosted through LTM (say, of calls / min) and then reject requests for a specific call that exceed the defined throttle? For example, let's say i have a restful api hosted of a pool of web servers through a single vip @ Client_id could be a number of clients with access, and I want to use and iRule (or something) on the F5 to start rejecting requests based on a defined threshold for client_id 123 when they exceed said threshold.

Any thoughts (or anyone who has actually implemented such a thing) would be super helpful! Thanks!