The Apache Commons Math project is a library of lightweight, self-contained mathematics and statistics components addressing the most common practical problems not immediately available in the Java programming language or commons-lang.

The Commons Jexl library is an implementation of the JSTL Expression Language with extensions.

The Apache Commons Digester package lets you configure an XML to Java object mapping module which triggers certain actions called rules whenever a particular pattern of nested XML elements is recognized.

Commons XMLSchema is a light weight schema object model that can be used to manipulate or generate XML schema.

OpenCMIS Commons API

Apache Sling JSON Library

Java library for dynamic proxying

OData Commons API

OpenCMIS Commons Implementation

OData Commons Core