eXtensible and fleXible Library


XXL is a Java library that contains a rich infrastructure for implementing advanced query processing functionality. The library offers low-level components like access to raw disks as well as high-level ones like a query optimizer. On the intermediate levels, XXL provides a demand-driven cursor algebra, a framework for indexing and a powerful package for supporting aggregation. The XXL project provides various packages. See the longer introduction to XXL for an explanation of the packages. The library is publicly available under GNU LGPL and comes with a full documentation.


June 2011
Version 2.0 Beta is now under googlecode

Visit the xxl.googlecode.com page for more details.

March 2006
Version 1.1 Beta 3 of XXL released!
Our latest release provides major changes to PIPES plus new functionality including metadata management, heartbeats, plan migration, CQL parsing, etc. Furthermore, it contains extensions and bug-fixes for several classes in XXL.

Visit the Download page for more details.

January 2005
Online version of XXL-Viewer available!
Experience the rich functionality of XXL with the XXL-Viewer, a powerful tool for visual java programming.

Visit the XXL page for more details.

Dezember 2004
Online demo of PIPES available!
Start our online demo of PIPES and execute continuous queries over data streams in traffic management as well as in an online auction.

Visit the PIPES page for more details.

November 2004
Version 1.1 Beta 2 of XXL released!
Our latest release includes several extensions for PIPES and several bug-fixes for B+-Trees.

Visit the Download page for more details.

May 2004
Version 1.0 of XXL released!
We proudly present version 1.0 of XXL including much more functionality, a full documentation as well as many use-cases.

Visit the Download page for more details and a link to the library download.


The XXL-Viewer offers an intuitive way of visual Java programming. We already presented this powerful tool at the SIGMOD conference 2004. Feel free to start our online version. In order to become familiar with the XXL-Viewer, read our tutorial (soon also available in english) that describes the basic steps.

Since our library XXL is completely developed in Java, the XXL-Viewer provides an easy access to the functionality of XXL. Just add xxl.jar to the classpath by calling "Add jar" in the explorer of the XXL-Viewer and you can explore XXL.

In order to get familiar with the XXL-Viewer, examine a simple awt example by opening this file with the XXL-Viewer. A more complex example modeling a continuous query over traffic data is illustrated here. Note that running the XXL-Viewer requires Java Web Start.

Credits and Contact

Prof. Dr. Bernhard Seeger

Graduate: Undergraduate: Alumni:
Michael Cammert Martin Ander Björn Blohsfeld, T-Systems
Evangelos Dellis Kay Bürger Jochen van den Bercken, IXOS AG
Christoph Heinz Tim Dörnemann Jens-Peter Dittrich, SAP AG
Jürgen Krämer Maxim Schwarzkopf  
Tobias Riemenschneider Sonny Vaupel  
Martin Schneider    
Akrivi Vlachou    
Ilya Vladimirskiy    

For support and questions feel free to send us an e-mail: request@xxl-library.de.

If you want to be informed on new versions of XXL you can subscribe to our mailing-list.
Send an email to xxl-request@lists.uni-marburg.de without subject and the word "subscribe" in the message body.