Robin Moffatt has an interesting architecture and implementation for Kafka:
Trains are an excellent source of streaming data—their movements around the network are an unbounded series of events. Using this data, Apache Kafka® and Confluent Platform can provide the foundations for both event-driven applications as well as an analytical platform. With tools like KSQL and Kafka Connect, the concept of streaming ETL is made accessible to a much wider audience of developers and data engineers. The platform shown in this article is built using just SQL and JSON configuration files—not a scrap of Java code in sight.
The code is also available in a GitHub repo.