sdks/java/io/kafka/README.md

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KafkaIO contains I/O transforms which allow you to read/write messages from/to [Apache Kafka](http://kafka.apache.org/).

## Dependencies

To use KafkaIO you must first add a dependency on `beam-sdks-java-io-kafka`. KafkaIO supports
multiple versions of Kafka clients at run time. It does not pull a specific version `kafka-clients`
transitively. You need to include a compatible version of `kafka-clients` as runtime dependency.
Usually current and recent versions of Kafka are supported, please see JavaDoc for KafkaIO for
complete list.

```maven
<dependency>
    <groupId>org.apache.beam</groupId>
    <artifactId>beam-sdks-java-io-kafka</artifactId>
    <version>...</version>
</dependency>

<dependency>
  <groupId>org.apache.kafka</groupId>
  <artifactId>kafka-clients</artifactId>
  <version>a_recent_version</version>
  <scope>runtime</scope>
</dependency>
```

## Documentation

The documentation is maintained in JavaDoc for KafkaIO class. It includes
 usage examples and primary concepts.
- [KafkaIO.java](src/main/java/org/apache/beam/sdk/io/kafka/KafkaIO.java)

### Protobuf tests
This recreates the proto descriptor set included in this resource directory.

```bash
protoc \
 -Isdks/java/io/kafka/src/test/resources/ \
 --descriptor_set_out=sdks/java/io/kafka/src/test/resources/proto_byte/file_descriptor/proto_byte_utils.pb \
 sdks/java/io/kafka/src/test/resources/proto_byte/proto_byte_utils.proto
```