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No public RPCs will be changed or created.  No new public methods will be added to clients.  A new public exception, ObsoleteVersionException, will be created.

There will be a new command which allows system administrators to find out what RPCs versions all brokers in the cluster support.  It will make an ApiVersionRequest to each broker, and then print out the results.  This may be useful for debugging and troubleshooting version compatibility issues.

The new command will be called BrokerVersionCommand.  It will print out broker versions on the command line.  The format will show the version range for each broker, as follows:

cmccabe@aurora:~/src/kafka> ./bin/kafka-broker-versions.sh --bootstrap-server localhost:9092 --listApiVersions
aurora:9092 (id: 0 rack: null) -> {
 Produce(0): 0 to 2,
 Fetch(1): 0 to 3,
 Offsets(2): 0 to 1,
 Metadata(3): 0 to 2,
 LeaderAndIsr(4): 0,
 StopReplica(5): 0,
 UpdateMetadata(6): 0 to 2,
 ControlledShutdown(7): 1,
 OffsetCommit(8): 0 to 2,
 OffsetFetch(9): 0 to 1,
 GroupCoordinator(10): 0,
 JoinGroup(11): 0 to 1,
 Heartbeat(12): 0,
 LeaveGroup(13): 0,
 SyncGroup(14): 0,
 DescribeGroups(15): 0,
 ListGroups(16): 0,
 SaslHandshake(17): 0,
 ApiVersions(18): 0,
 CreateTopics(19): 0,
 DeleteTopics(20): 0
}

Migration Plan and Compatibility

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