Building and Deploying Kafka Schema Registry

To build and deploy Kafka Schema Registry with Maven, you must first install development versions of Kafka common and rest-utils utilities.

You can run Kafka Schema Registry instances on several cluster nodes. One node is the primary node and the other ones are secondary nodes.

Kafka Schema Registry requires ZooKeeper and HPE Ezmeral Data Fabric Streams.

The REST interface to schema registry includes a built-in Jetty server. The wrapper scripts bin/schema-registry-start and bin/schema-registry-stop are the recommended methods for starting and stopping the service.

In Apache Kafka, a schema is produced when:
  • A message is produced and there is no equivalent schema in the schema registry
  • A schema is created for key or value portion of the message
The associated schema subject is a “topic-key”:
  • Each schema is associated with a version
  • Every schema gets a globally unique ID
The consumer gets the messages’ schema using the schema ID: 
$ curl -X GET http://localhost:8087/schemas/ids/1
        {"schema":"\"string\""}
You can also query a schema for a given topic using the associated schema subject. For example, for topic1 (for either key or value), schema, all, latest, or specific schema versions can be queried using the following REST commands: 
$ curl -X GET http://localhost:8087/subjects/topic1-value/versions
     [1]
$ curl -X GET http://localhost:8087/subjects/Kafka-value/versions/1
     {"subject":"Kafka-value","version":1,"id":1,"schema":"\"string\""}
$ curl -X GET http://localhost:8087/subjects/Kafka-value/versions/latest
     {"subject":"Kafka-value","version":1,"id":1,"schema":"\"string\""}

For a complete list of supported APIs, see Confluent Schema Registry API Reference.