[SOLVED] What is the recommended way to create a Custom Sink for AWS Sagemaker Feature Store in Apache Flink?

What is the recommended way to create a Custom Sink for AWS Sagemaker Feature Store in Apache Flink?

I want to create a Custom Apache Flink Sink to AWS Sagemaker Feature store, but there is no documentation for how to create custom sinks on Flink's website. There are also multiple base classes that I can potentially extend (e.g. AsyncSinkBase, RichSinkFunction), so I'm not sure which to use.

I am looking for guidelines regarding how to implement a custom sink (both in general and for my specific use-case). For my specific use-case: Sagemaker Feature Store has a synchronous client with a putRecord call to send records to AWS Sagemaker FS, so I am ideally looking for a way to create a custom sink that would work well with this client. Note: I require at at least once processing guarantees, as Sagemaker FS is DynamoDB (a key-value store) under the hood.

Java Client: https://docs.aws.amazon.com/AWSJavaSDK/latest/javadoc/com/amazonaws/services/sagemakerfeaturestoreruntime/AmazonSageMakerFeatureStoreRuntime.html
Example of the putRecord call using the Python client: https://github.com/aws-samples/amazon-sagemaker-feature-store-streaming-aggregation/blob/main/src/lambda/StreamingIngestAggFeatures/lambda_function.py#L31

What I've Found so Far

Some older articles which say to use org.apache.flink.streaming.api.functions.sink.RichSinkFunction and SinkFunction
Some connectors using classes in org.apache.flink.connector.base.sink.writer (e.g. AsyncSinkWriter, AsyncSinkBase)
This section of the Flink docs says to use the SourceReaderBase from org.apache.flink.connector.base.source.reader when creating custom sources; SourceBaseReader seems to be the equivalent source to the sink classes in the bullet above

Any help/guidance/insights are much appreciated, thanks.

Solution