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In AWS, racks are usually mapped to the concept of availability zones. 

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.

A public interface is any change to the following:

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Binary log format

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The network protocol and api behavior

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Any class in the public packages under clientsConfiguration, especially client configuration

• org/apache/kafka/common/serialization

• org/apache/kafka/common

• org/apache/kafka/common/errors

• org/apache/kafka/clients/producer

• org/apache/kafka/clients/consumer (eventually, once stable)

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Monitoring

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Command line tools and arguments

The RackLocator interface will be used to return rack information for brokers. It is defined as:

/**
 * Interface that defines API to get broker to rack mapping. This is used by
 * rack aware replica assignment. The implementation class can be passed as
 * rack.locator.class property at server start up or -rack-locator-class command\
 * line argument for TopicCommand.
 *
 * @param zkClient ZkClient for the cluster that can be used to retrieve information
 *                 from ZooKeeper
 * @param props Properties used by implementation.
 */
abstract class RackLocator(val zkClient: ZkClient, val props: Properties) {
  def getRackInfo(): Map[Int, String]
}

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Proposed Changes

Describe the new thing you want to do in appropriate detail. This may be fairly extensive and have large subsections of its own. Or it may be a few sentences. Use judgement based on the scope of the change.

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