Is it possible to use Protocol Buffers with DynamoDB.

Your question is a little vague, are you asking how to store the protobuf data in DynamoDB? You can store binary data in DynamoDB using the Binary Data Type listed here.

I've not used protobufs in Java, but I have in Node using the protobufjs NPM package. I am sure you can do likewise by adding a needed package to your pom file.

DynamoDB API only support JSON, hence to store binary data, that is your Protobuf encoded payload, you need to first convert it to Base64. https://docs.aws.amazon.com/amazondynamodb/latest/developerguide/Programming.LowLevelAPI.html#Programming.LowLevelAPI.Binary

The stored binary data occupies the raw byte length.

https://docs.aws.amazon.com/amazondynamodb/latest/developerguide/CapacityUnitCalculations.html

You can also handle binary data in Java using the Document API. https://docs.aws.amazon.com/amazondynamodb/latest/developerguide/JavaDocumentAPIBinaryTypeExample.html