...

{
 "schema": {
 "type": "struct",
 "fields": [{
 "type": "int32",
 "optional": true,
 "field": "c1"
 }, {
 "type": "string",
 "optional": true,
 "field": "c2"
 }, {
 "type": "int64",
 "optional": false,
 "name": "org.apache.kafka.connect.data.Timestamp",
 "version": 1,
 "field": "create_ts"
 }, {
 "type": "int64",
 "optional": false,
 "name": "org.apache.kafka.connect.data.Timestamp",
 "version": 1,
 "field": "update_ts"
 }],
 "optional": false,
 "name": "foobar"
 },
 "payload": {
 "c1": 10000,
 "c2": "bar",
 "create_ts": 1501834166000,
 "update_ts": 1501834166000
 }
}

Public Interfaces

Briefly list any new interfaces that will be introduced as part of this proposal or any existing interfaces that will be removed or changed. The purpose of this section is to concisely call out the public contract that will come along with this feature.

A public interface is any change to the following:

• Binary log format

• The network protocol and api behavior

• Any class in the public packages under clientsConfiguration, especially client configuration

  • org/apache/kafka/common/serialization

  • org/apache/kafka/common

  • org/apache/kafka/common/errors

  • org/apache/kafka/clients/producer

  • org/apache/kafka/clients/consumer (eventually, once stable)

• Monitoring

• Command line tools and arguments

• Anything else that will likely break existing users in some way when they upgrade

Proposed Changes

The "schema" is a necessary component in order to dictate to the JsonConverter how to map the payload's JSON datatypes to Kafka Connect datatypes on the consumer side, and certain Sink Connectors absolutely require a schema in order for them to function (eg: JdbcSinkConnector). Instead of requiring explicitly defined schemas within all json records from every producer that is part of a data pipeline where a Sink Connector will consume its records, the JsonConverter should have the ability to make inferences based on the contents of the JSON data.

Public Interfaces and Proposed Changes

This proposal introduces a new configuration that would be read by all instances of the JsonConverter. In order to activate it, individual connectors can set this as a connector property, or users can set this as a worker property:

value.converter.schemas.infer.enable: "true"

The default value for this configuration is false, and the original behavior of passing along SchemaAndValue objects with a null schema to downstream sink connector logic is observed. However, if this configuration is set to "true", the JsonNodeType of each JSON node will be used to draw an inference as to the Kafka Connect datatype that most closely resembles that piece of data. For instance, if our data was:

 Describe the new thing you want to do in appropriate detail. This may be fairly extensive and have large subsections of its own. Or it may be a few sentences. Use judgement based on the scope of the change.

Compatibility, Deprecation, and Migration Plan

...