adam bien's blog
Ruby on Rails Was Supposed To Kill Java... Now Twitter Kills Rails 📎
...Last week, we launched a replacement for our Ruby-on-Rails front-end: a Java server we call Blender. We are pleased to announce that this change has produced a 3x drop in search latencies and will enable us to rapidly iterate on search features in the coming months...
...To ensure a high quality of service while introducing Blender into our system (=twitter.com), we are using the old Ruby on Rails front-end servers as proxies for routing thrift requests to our Blender cluster. Using the old front-end servers as proxies allows us to provide a consistent user experience while making significant changes to the underlying technology. In the next phase of our deploy, we will eliminate Ruby on Rails entirely, connecting users directly to Blender and potentially reducing latencies even further...
-@twittersearch
From http://engineering.twitter.com/2011/04/twitter-search-is-now-3x-faster_1656.html
Btw. I do not believe, that Java (EE) will kill Ruby on Rails either. Just use the right tool for the job (and Java for highly scalable apps)...