avro schema for key and value for confluent kafka schema registry

[leonardotorresaltez]

Hello i am looking some example in the spec version 3.0 about using different avro schemas for key and value.
both schemas live in confluent schema registry .

How to specify a message key and value in asyncapi contract ?

regards,
Leonardo

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[Karan-Palan]

Hey @leonardotorresaltez , from what I understand using Async Api in my project, you can specify different Avro schemas for the key and value in a Kafka message by using schemaFormat and defining separate schemas for the key and value.

Example:
You can define the message like this:

asyncapi: 3.0.0
info:
  title: Kafka Avro Example
  version: 1.0.0
servers:
  kafka-broker:
    url: kafka.example.com:9092
    protocol: kafka
    description: Kafka broker

channels:
  my-topic:
    address: my-topic
    messages:
      key:
        contentType: application/vnd.apache.avro+json
        schemaFormat: application/vnd.apache.avro+json
        schema:
          $ref: "#/components/schemas/KeySchema"
      value:
        contentType: application/vnd.apache.avro+json
        schemaFormat: application/vnd.apache.avro+json
        schema:
          $ref: "#/components/schemas/ValueSchema"

components:
  schemas:
    KeySchema:
      type: string  # Example: Could also be an Avro schema reference
    ValueSchema:
      type: object
      properties:
        id:
          type: string
        name:
          type: string

Here,

1. The key and value fields in the messages section allow you to define separate schemas.
2. schemaFormat: application/vnd.apache.avro+json ensures that Avro is used.
3. The KeySchema and ValueSchema are defined separately in components.schemas.

Would this approach work for your use case?