• Java Development Kit (JDK) 1.8
• Apache Maven and install a Maven binary archive

mvn clean package

Flink has 3 types of custom streaming source:

• Implements SourceFunction with single parallelism.
• Implements ParallelSourceFunction with multi parallelism.
• Implements RichParallelSourceFunction with multi parallelism, with open() to initialize resource, close() to dispose resource.

Flink has 2 types of custom streaming sink:

• Implements SinkFunction with single parallelism.
• Implements RichSinkFunction with single parallelism, with open() to initialize resource, close() to dispose resource.

Flink has raised new kind of Source & Sink API for Batch Stream Alignment

• FLIP-27: Refactor Source Interface
• FLIP-143: Unified Sink API