The Sandbox
This project also contains a workspace that is open to all Jakarta committers. It's a place to try out new ideas and prepare for inclusion into the Commons portion of the project or into another Jakarta project. Users are free to experiment with the components developed in the sandbox, but sandbox components will not necessarily be maintained, particularly in their current state.
Sandbox 

Cache Cache provides object caching services. 
Clazz Clazz focuses on introspection and class manipulation. 
Compress Commons Compress defines an API for working with tar, zip and bzip2 files. 
Contract This component makes all the nice features available to the java programming language that come along with contract based programming. 
Convert Commons-Convert aims to provide a single library dedicated to the task of converting an object of one type to another. 
Events Commons-Events provides additional classes for firing and handling events. It focusses on the Java Collections Framework, providing decorators to other collections that fire events. 
Feedparser Generic FeedParser interface and concrete implementations for Atom, FOAF, OPML and RSS. 
Functor A functor is a function that can be manipulated as an object, or an object representing a single, generic function. 
I18n This component adds the feature of localized message bundles that consist of one or many localized texts that belong together. Think of an error message that consists of title, text, summary and error details. 
Id Id is a component used to generate identifiers. 
Javaflow Continuation implementation to capture the state of the application. 
JCI Java Compiler Interface 
JJar Jakarta JAR Archive Repository 
Mapper Mapper is a thin abstraction layer around a project's chosen data mapping technology (a.k.a. DAO pattern). 
Messenger Messenger is an easy to use and lightweight framework for working with JMS in the web tier. 
Pipeline This component provides a set of pipeline utilities designed around work queues that run in parallel to sequentially process data objects data objects. 
Scaffold Scaffold is a toolkit for building web applications. 
SQL Commons SQL is a component for working with databases and generating DDL. It contains a simple set of beans that represent a relational database schema such as a Database, Table, Column etc. 
ThreadPool ThreadPool is a simple component for asynchronously dispatching work to another thread in a pool for simple multi threaded programming. 

Workflow Workflow provides a framework for building workflow management systems. 

XMLIO Simple and fast importer for XML configuration or import files.