Apache Storm is a free and open source distributed realtime computation system. Storm makes it easy to reliably process unbounded streams of data, doing for realtime processing what Hadoop did for batch processing. Storm is simple, can be used with any programming language.
Apache Storm can be used for real-time analytics, continuous computation, distributed RPC, ETL, and more. It is scalable, fault-tolerant, guarantees your data will be processed, and is simple to set up and operate.