Apache Kafka

Apache Kafka is a distributed event streaming platform. 

It supports publish, subscribe operations (similar to a message queue) and stores streams of records in a fault-tolerant way.

The basic object in Kafka is an array of bytes with some optional metadata known as the key. 

Messages may be structured according to a schema (possibly using JSON or XML) although Apache Avro, a serialization framework for Hadoop, is increasingly popular. Avro supports strong typing and schema evolution.

The Real Kafka - Kafka was a writer who was born in Prague (at the time part of the mighty Austro-Hungarian empire). His well-known works include "Die Verwandlung" (The Metamorphosis) first published in 1915.

Castor

To quote castor.org, Castor is an "Open Source data binding framework for Java[tm]", the "shortest path between Java objects, XML documents and relational tables". We have Java-to-XML binding, Java-to-SQL persistence and more. Looked at in reverse, you can think of it as a Java persistence layer. It was developed by some guys at Intalio, Inc. Castor uses JUnit to build and test components.