While it almost certainly remains the largest Ruby on Rails based site in the world, Twitter has gradually been moving more and more of its stack to the JVM. Last year the company announced that its back-end message queue had been re-written in Scala, and more recently it moved the search stack to Java, making Twitter search around three times faster.
Citing a need to be able to respond faster to events, and disappointment in both feature set and timeframe for Java 7, the guardian.co.uk team is using Scala rather than Java for new projects. 12
This article aims to provide more insight into the motivation and technical challenges that the LinkedIn team faced, while combining Scala, JRuby and Voldemort, at such scale.
Scala and Spring are a promising match. Based on a concrete example, this article shows how the power of Scala combined with the proven and productive Spring framework can be unleashed. 5