Flink Stream/Batch Unified Connector API Example Prerequisites Java Development Kit (JDK) 1.8 Apache Maven and install a Maven binary archive Build Flink Job mvn clean package Custom Flink Stream/Batch Unified Source & Sink API source FLIP-27: Refactor Source Interface sink FLIP-143: Unified Sink API Implements SinkFunction with single parallelism. Implements RichSinkFunction with single parallelism, with open() to initialize resource, close() to dispose resource.