Sentinel is a monitor on HQ the backend business logic layer for HQ that Caliper API reaches out to. Sentinel looks at the login and money movement of any kind and maybe a few other things. The endpoints from Caliper API that may invoke some Sentinel calls are the ACH endpoints, the Authenticate endpoint, and the fundstransfer endpoint. It is possible it might be invoked on other calls, but I don't think so.

-Trey