node-kafka-schema-registry

There are two options for Schema Registry, mainly

• Confluent Schema Registry
• Apicurio Schema Registry

Both works with the following:

• Avro (default)
• Protobuf
• JsonSchema

However, Confluent Schema Registry will store the schemas in Kafka while Apicurio Schema Registry has several options including in-memory and Postgresql.

If storage is an important consideration, then choose Apicurio.

Confluent Schema Registry

Start

$ make up

Stop

$ make down

APIs

Reference here.

# Get schemas.
$ curl localhost:8081/schemas | jq

# Get schema by id.
$ curl localhost:8081/schemas/ids/{id} | jq

# Get schema versions by id.
$ curl localhost:8081/schemas/ids/{id}/versions | jq

$ curl localhost:8081/schemas/types | jq

# Get subjects.
$ curl localhost:8081/subjects | jq


# Update compatibility for subject
$ curl -X PUT -H 'Content-Type: application/vnd.schemaregistry.v1+json' localhost:8081/config/examples\.RandomTest -d '{"compatibility": "FORWARD"}'

Apicurio Schema Registry

$ open http://localhost:8080/apis

For Confluent Schema Registry compatible APIs, use the host endpoint:

$ localhost:8080/apis/ccompat/v7
$ curl localhost:8080/apis/ccompat/v7/subjects

Proto compatiblity issue:

https://github.com/Apicurio/apicurio-registry/issues/1334

Example for schemas/proto/person_v3.proto works for Confluent Schema Registry, but is marked as not backward compatible by Apicurio.

Schema Management

Since many producers/consumers may make use of the schema, the schemas should probably be stored in a centralized repo.

The repo can then provide clients/package to export the subjects of the schema for ease of use.

The migration of the schemas should be done externally before the schema can be used by consumers/producers. The application should not perform the registration, otherwise there may be attempts from different applications registering different schemas at the same time.

References

• https://www.confluent.io/blog/schema-registry-for-beginners/
• https://docs.confluent.io/platform/current/schema-registry/avro.html#forward-compatibility