Status

Current state: [Under Discussion]

Discussion thread: here [Change the link from the KIP proposal email archive to your own email thread] 

JIRA: here 

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

Motivation

window.size.ms  is not a true KafkaStreams config, and results in an error when set from a KStreams application. It belongs on the client.

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.

• client configuration

• docs/streams/developer-guide/config-streams

Proposed Changes

I propose we remove deprecate window.size.ms  from StreamsConfig  and move it to ClientConfig  in StreamsConfig.

Note: It might seem that `window.inner.serde` is similar, but if you refer to TimeWindowedSerializer  you will see that it is indeed used by KafkaStreams. 

Compatibility, Deprecation, and Migration Plan

• What impact (if any) will there be on existing users? Removing Deprecating it from in StreamsConfig  shouldn't impact current users negatively : other than them seeing a warning when they use it in KStreams.  

• If we are changing behavior how will we phase out the older behavior? We should change the config docs first , and then remove the configurationto deprecate. In the future, moving the configuration to ClientConfig could be called for. See https://github.com/apache/kafka/pull/14360 for a PR in progress, as well as a discussion of this issue.
• If we need special migration tools, describe them here. N/A
• When will we remove the existing behavior? Post docs change , hopefully before 3.6.2.and deprecation, for major release 5. Deprecation itself can be for next minor release. 

Test Plan

should not impact tests directlyCould be covered with a unit test to check that a warning is displayed when used.

Rejected Alternatives

Currently N/A.