Doc here. If you want a trace, then a web app is way to slow. In theory it should be plenty fast, but in practice, the connection is neither reliable, nor fast. Have you asked the guys at Polar? I worked with a Mech E team on a bicycle wheel design; they got the DuPont engineer who designed the original trifoil wheel to help. It would be worth asking. Look up "holter monitor". I'd think there must be some C libraries for this.