ActiveMQ is a popular messaging queue. It will be great for Samza to be able to read from and write to it. The basic idea is:
1. it will be separated into its own package
2. it implements SystemAdmin, SystemConsumer, SystemProducer. ( check the org.apache.samza.system package in javadoc )
3. it is written in Java. Thought previous implementation is using Scala (Kafka Implementation and FileSystem Implementation), we are moving from Scala to Java. All scala APIs are Java APIs.
4. two systems mentioned in (3) could be used as a reference.
Also see comment.