Kafka Streams is a library for streaming applications that transform input Kafka topics into output Kafka topics (calls to external services or updates to databases).
KSQL is SQL engine for Kafka. It allows SQL queries to analyze a stream of data in real time.
Nowadays, we invariably operate in ecosystems: groups of applications and services which work towards some higher level goal. When we make the systems event-driven they’re available with a spread of advantages. The primary is that the concept we’ll rethink the services simply as a mesh of remote requests and responses, decoupling each event source from its consequences.