In addition to command line tooling for management and administration tasks, Kafka has five core APIs for Java and Scala :
* The Admin API to manage and inspect topics, brokers, and other Kafka objects.
* The Producer API to publish (write) a stream of events to one or more Kafka topics.
* The Consumer API to subscribe to (read) one or more topics and to process the stream of events produced to them.
* The Kafka Streams API to implement stream processing applications and microservices. It provides higher-level functions to process event streams, including transformations, stateful operations like aggregations and joins, windowing, processing based on event-time, and more. Input is read from one or more topics in order to generate output to one or more topics, effectively transforming the input streams to output streams.
* The Kafka Connect API to build and run reusable data import/export connectors that consume (read) or produce (write) streams of events from and to external systems and applications so they can integrate with Kafka. For example, a connector to a relational database like PostgreSQL might capture every change to a set of tables. However, in practice, you typically don't need to implement your own connectors because the Kafka community already provides hundreds of ready-to-use connectors.
