Status

Current state: Adopted

Discussion thread: here 

JIRA:  

Please keep the discussion on the mailing list rather than commenting on the wiki (wiki discussions get unwieldy fast).

Motivation

Over time, certain exceptions and methods within the Kafka Streams exception handling interfaces are unused in favor of newer, more comprehensive alternatives. Retaining these deprecated elements can lead to confusion, and complicates future development and maintenance. This KIP proposes the deprecation and removal of BrokerNotFoundException and improve code clarity.

Public Interfaces

The removal will affect the public exceptions of Kafka Streams. Users who are still using the BrokerNotFoundException  class will encounter compilation errors.

Proposed Changes

This KIP proposes to remove BrokerNotFoundException which is unused since Kafka Streams 2.8.

This change goes in two steps

Step1: mark unused BrokerNotFoundException as deprecated in 4.2 release

Step2: remove the deprecated exception in the next major release which can be 5.0

Unused Exception for Deprecation and Removal:

• org.apache.kafka.streams.errors.BrokerNotFoundException

Compatibility, Deprecation, and Migration Plan

• Compatibility: This change is not backward compatible at the source code level for users who are still using the BrokerNotFoundException class.
• Deprecation: The BrokerNotFoundException was unused since Kafka Streams version 2.8. 
  • Given that BrokerNotFoundException is unused, we can mark it deprecated in 4.2, making their removal appropriate in 5.0 as sufficient deprecation period will be passed.
• Migration Plan:
  • Users should remove any handling of BrokerNotFoundException as it is no longer relevant.

Test Plan

This is a code cleanup. Existing test suite should catch any failures. Will add or update new unit tests as needed.

Rejected Alternatives

Since BrokerNotFoundException is not used for a very long time, we can remove it directly. But, the protocol we follow is to deprecate them first and then remove them in the next major release.

We will have an unused class lying around for another release. Other than that, there is no damage if we follow the regular process. Hence, the two step process.