Riemann (http://riemann.io) is a new framework for monitoring distributed systems. It's particular useful for sending ad-hoc events such as, heartbeats and metrics. It would be nice if NiFi had a PutRiemann processor for writing events using the NiFi expression language.
A simple use case would be a data flow that repeatedly checks specific services over TCP, HTTP, etc and checks into Riemann. Another example would be detecting a blip in events coming down a stream using a simple event heartbeat mechanism. I'll post a couple visuals to help make these examples more concrete.
I have an initial PutRiemann processor made. I will post the patch via a Github pull request later today.