YANG Kafka native extensions

This repo provides components needed for native YANG in apache Kafka. Currently, includes the following components:

1. yang-schema-registry-plugin: A plugin for Confluent's schema register
2. TODO json and cbor serdes

Configuring yang-schema-registry-plugin

1. Download and configure Confluent platform: see https://docs.confluent.io/platform/7.5/installation/installing_cp. For the purpose of this documentation, we denote the installation dir of Confluent's platform as ${CONFLUENT_DIR}
2. build the current project mvn package
3. Copy the yang-schema-registry-plugin-0.1-shaded.jar to Confluent's schema registry java libs directory

   cp yang-schema-registry-plugin/target/yang-schema-registry-plugin-0.1-shaded.jar ${CONFLUENT_DIR}/share/java/schema-registry/

4. Enable the yang schema plugin by added the line schema.providers=com.swisscom.kafka.schemaregistry.yang.YangSchemaProvider to ${CONFLUENT_DIR}/etc/schema-registry/schema-registry.properties

   echo 'schema.providers=com.swisscom.kafka.schemaregistry.yang.YangSchemaProvider' >> ${CONFLUENT_DIR}/etc/schema-registry/schema-registry.properties

5. Restart the schema registry. When the plugin is loaded successfully, a log containing the message [ INFO] - io.confluent.kafka.schemaregistry.storage.KafkaSchemaRegistry -KafkaSchemaRegistry.java(272) -Registering schema provider for YANG: ch.swisscom.kafka.schemaregistry.yang.YangSchemaProvider is printed