What are some alternatives?
When comparing twitter.github.io Kestrel and Apache Spark, you can also consider the following products
nginx - A high performance free open source web server powering busiest sites on the Internet.
Hive - The Productivity Platform
CloudAMQP - CloudAMQP automates every part of setup, running and scaling of RabbitMQ clusters. Available on all major cloud and application platforms.
Hadoop - Open-source software for reliable, scalable, distributed computing
RabbitMQ - RabbitMQ is an open source message broker software.
Hortonworks - Hadoop-Related