How does Schema Registry in Kafka work and why is it needed?

Schema Registry in Kafka is a service that stores and manages data schemas (such as Avro, JSON Schema, Protobuf) used for message serialization in Kafka.

Purpose:

• Ensures consistency of message formats between producers and consumers.
• Allows versioning of schemas, simplifying data evolution without breaking compatibility.
• Reduces message size by storing schemas separately and transmitting only the schema ID.

How it works:

1. The producer serializes data according to the schema registered in the Schema Registry when sending a message.
2. Instead of the full schema, a reference (ID) to the schema is sent in the message.
3. The consumer, upon receiving the message, requests the schema by ID from the Registry and deserializes the data.

This guarantees that all system participants use consistent data formats and simplifies management of changes in message structure.