OLAP server written in Java

 Mondrian is an OLAP server written in Java. It enables to interactively
 analyze very large datasets stored in SQL databases without writing SQL.
 .
 It can be used for :
  * High performance, interactive analysis of large or small volumes of
    information
  * "Dimensional" exploration of data, for example analyzing sales by product
    line, by region, by time period
  * Parsing of Multi-Dimensional eXpression (MDX) language into Structured Query
    Language (SQL) to retrieve answers to dimensional queries
  * High-speed queries through the use of aggregate tables in the RDBMS
  * Advanced calculations using the calculation expressions of the MDX language