1. Apache Software Foundation (2017a) Apache Hadoop project web page.
https://hadoop.apache.org/
2. Apache Software Foundation (2017b) Apache Kafka project web page.
https://kafka.apache.org/
3. Apache Software Foundation (2017c) Apache Samza project web page.
https://samza.apache.org/
4. Apache Software Foundation (2017d) Apache ZooKeeper project web page.
https://zookeeper.apache.org/
5. Facebook Inc (2017) RocksDB project web page.
http://rocksdb.org/