Compass provides real time searchengine built on top of Lucene. It is distributed, transcational, supports Spring MVC, integrates with ORM. Simple Compass provides a simple API for working with Lucene. If you know how to use an ORM, then you will feel right at home with Compass with simple operations for save, and delete & query. Compass provides google-style search, index updates as well as more advanced concepts such as caching and index sharding (sub indexes). Compass also uses built in optimizations for concurrent commits and merges.
It provides support to map Object, JSON, XML to search engine mapping. It allows storing the index with Data Grid products such as GigaSpaces, Coherence and Terracotta.