XXL provides a powerful collection of easy-to-use index-structures, query operators and algorithms facilitating the performance evaluation of new query processing developments. Query algorithms in XXL use the same set of basic classes, like I/O routines and improved (de)serialization methods. Index structures include B-trees, R-trees, M-trees, AVL-trees, Red-Black-trees and bulk-loading-algorithms. Also includes VisualXXL which is a graphical query engine. Requires Java 3D.