The Confluent KAFKA Kotlin Sample Code demonstrates how to produce messages to and consume messages from a Kafka cluster using the Kotlin version of Java Producer and Consumer and the Kafka Streams API. A prerequisite includes Java 1.8 or higher to run the demo application.
gRPC is an alternative architectural pattern to REST and GraphQL for providing and consuming APIs. It's becoming a popular way among many companies to create APIs intended to run at web-scale compared to the other architectures that often rely on data formatting standards such as JSON or XML.
There are a number of ways of delivering data in real-time but until recently it has looked like PubSubHubbub, with the backing of Google, was going to be the preferred method. However, the past couple of weeks have seen a couple of interesting developments which could indicate that the developer community may actually prefer HTTP Streaming.