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https://issues.apache.org/jira/browse/KAFKA-4635?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15827057#comment-15827057
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Colin P. McCabe commented on KAFKA-4635:
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Thanks for filling in the notes.
#5 is implemented by the patch up at KAFKA-4630
For #4, I'm not sure if we can give a reasonable error message for pre-0.10.0
brokers, since the broker will simply disconnect us as soon as we attempt to
invoke ApiVersionsRequest. We could add a test that the disconnection happens
as expected.
With regard to #9, what kind of note would be appropriate?
> Client Compatibility follow-up
> ------------------------------
>
> Key: KAFKA-4635
> URL: https://issues.apache.org/jira/browse/KAFKA-4635
> Project: Kafka
> Issue Type: Sub-task
> Components: clients
> Reporter: Ismael Juma
> Assignee: Colin P. McCabe
> Fix For: 0.10.2.0
>
>
> I collected a number of improvements that I think would be good to do before
> the release. [~cmccabe], please correct if I got anything wrong and feel free
> to move some items to separate JIRAs.
> 1. OffsetAndTimestamp is a public class and the javadoc should only include
> the behaviour that users will see. The following (or part of it) should
> probably be a non-javadoc comment as it only happens internally:
> "* The timestamp should never be negative, unless it is invalid. This could
> happen when handling a response from a broker that doesn't support KIP-79."
> 2. There was a bit of a discussion with regards to the name of the exception
> that is thrown when a broker is too old. The current name is
> ObsoleteBrokerException. We should decide on the name and then we should
> update the relevant producer/consumer methods to mention it.
> 3. [~junrao] suggested that it would be a good idea log when downgrading
> requests as the behaviour can be a little different. We should decide the
> right logging level and add this.
> 4. We should have a system test against 0.9.0.1 brokers. We don't support it,
> but we should ideally give a reasonable error message.
> 5. It seems like `Fetcher.listOffset` could use `retrieveOffsetsByTimes`
> instead of calling `sendListOffsetRequests` directly. I think that would be a
> little better, but not sure if others disagree.
> 6. [~hachikuji] suggested that a version mismatch in the `offsetsForTimes`
> call should result in null entry in map instead of exception for consistency
> with how we handle the unsupported message format case. I am adding this to
> make sure we discuss it, but I am not actually sure that is what we should
> do. Under normal circumstances, the brokers are either too old or not whereas
> the message format is a topic level configuration and, strictly speaking,
> independent of the broker version (there is a correlation in practice).
> 7. We log a warning in case of an error while doing an ApiVersions request.
> Because it is the first request and we retry, the warning in the log is
> useful. We have a similar warning for Metadata requests, but we only did it
> for bootstrap brokers. Would it make sense to do the same for ApiVersions?
> 8. It would be good to add a few more tests for the usable versions
> computation. We have a single simple one at the moment.
> 9. We should add a note to the upgrade notes specifying the change in
> behaviour with regards to older broker versions.
> cc [~hachikuji].
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