Apache NiFi: Filter events and only let through the latest in a timeframe

In the IoT world, some devices generate large volumes of events that can be difficult for back-end systems to process in real time. Of course you can use NiFi to throttle messages. However, this will not be sufficient if the flow of events is consistently higher than what can be handled by the back-end system. A way to deal with this is to let Apache NiFi group and filter messages based on a specific attribute and only letting through the latest message for a specific device, in a certain timeframe. In this blog post I'll illustrate how you can do this. The trick is to merge several messages together using the MergeContent processor and then select the latest one using a Jolt transformation.