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Motivation

This KIP aims to solve two problems:1. There the problem that there is currently no way for a Kafka client to know which API version the broker supports. This means a client might not be able to perform its desired functionality, nor report any meaningful errors back to the application. Which leads in to the next problem, problem #2.

2. Unsupported requests are not handled gracefully by the broker. A broker receiving a protocol request it does not support will simply close the TCP connection to the client. From the client's point of view it has no way of knowing that the broker did not support the request, it could just as well be a network or software problem causing the connection reset.

 This makes it hard for clients and applications to support multiple versions of Kafka, which in turn limits the Kafka eco-system since applications and clients will need to be manually built or configured for a specific broker version.

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