MLSAM (née MLSQL) is an open source XQuery library (written by Jason Hunter of MarkLogic and Ryan Grimm of O'Reilly Media) that allows easy access to relational database systems from within the MarkLogic environment.
MLSAM lets you execute arbitrary SQL commands against any relational database (MySQL, Oracle, DB2, SQL Server, Derby, etc) and it captures the results as XML for processing within the MarkLogic environment. Using the library enables XQuery applications to leverage a relational database without having to resort to Java or C# glue code to manage the interaction.
The 1.1 release includes support for OUT and INOUT parameters. It also fixes an issue where update statements against Oracle would exception out during the fetching on non-existent generated keys.
MLSAM is distributed under the Apache License, Version 2.0.
Read the MLSAM Tutorial.