Schema Registry is a shared repository of schema that allows application to flexibly interact with each other.

1. Kafka Schema Registry
Managing Record Schema in Kafka
Presented By:
Manisha Dubaria

2. Agenda
• What is Schema Registry
• Flow of Schema Registry
• Data Serialization
• Configuration Options
• Format of data written in topic
• Restcall to Schema Registry
• Use of Schema Registry

3. What is Schema Registry
• A shared repository of schema that allows application to
flexibly interact with each other.
• It deals with Evolution of Schema in Message Record over
Time
• Schema Registry is used by Writer/Reader
– Senders/Producers use this schema while sending the
payloads according to the given schema
– Reader/Consumer uses this schema to project the received
payload written with a writers schema

4. Flow of Schema Registry
Producer ConsumerKafka Cluster
Schema
Registry
Registers Schema Asks for Schema

5. Data Serialization
• Data consumers should understand Data Producers
• Kafka handles schema evolution problem using avro serializer
and deserializer

6. Configuration Options
• Most important Configuration given to Producer and
Consumer is “schema.registry.url”
• Producer can set “auto.register.schemas” to true to
automatically register the schema to the registry
• There are two ways to provide the schema to Producer:
I. Include the Path of schema fie in pom of project and build the
project every time the schema is changed
II. Pass the schema File explicitly and build the project only once
independent of the change in schema file

7. Configuration Options

8. Configuration Options

9. Format of Data
• Either the message key or message value or both can be
serialized as Avro
• It has subject which defines a scope in which schemas can
evolve
• Schema Registry does compatibility checks only within the
schema subject
• The schema file is an avsc file which contains namespace,
type, name, fields
• Data in topic is stored as [MagicByte][Schema ID][Data]

10. Rest call to Schema Registry
• Registering a new version of Schema under subject
curl -X POST -H "Content-Type: application/vnd.schemaregistry.v1+json" --data
'{"schema": "{"type": "string"}"}' http://localhost:8081/subjects/Kafka-value/versions
• List all Subjects
curl -X GET http://localhost:8081/subjects
• Fetching a schema by globally unique Id
curl -X GET http://localhost:8081/schemas/ids
• Fetch Version 1 of the Schema Registered Under Subject
curl -X GET http://localhost:8081/subjects/Kafka-value/versions/1
• Deleting Version 1 of the Schema Registered Under Subject
curl -X DELETE http://localhost:8081/subjects/Kafka-value/versions/1
• Check the compatibility
curl -X POST -H "Content-Type: application/vnd.schemaregistry.v1+json" --data
'{"schema": "{"type": "string"}"}' http://localhost:8081/compatibility/subjects/Kafka-
value/versions/latest
• Checking top Level Config
curl -X GET http://localhost:8081/config

11. Use of Schema Registry
• Provides Reusable Schema
• Define relationships between schema
• To avoid attaching schema to every piece of data
• Producers and Consumers can evolve at different Rate