Ismael Juma created KAFKA-4635:
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Summary: Client Compatibility follow-up
Key: KAFKA-4635
URL: https://issues.apache.org/jira/browse/KAFKA-4635
Project: Kafka
Issue Type: Sub-task
Reporter: Ismael Juma
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.
cc [~hachikuji].
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