Harshad Oak 
Pro Jakarta Commons [PDF ebook] 

Jakarta Commons are easily reusable components that can quickly be put to good use in any server-side Java development undertaking. In fact, components are not big applications, but sleek code bits that perform specific tasks very well. This book provides much-needed documentation and usage information about the popular sub-projects forming Jakarta Commonsso that you can efficiently incorporate them into Java applications.Jakarta Commons have potential to extend the core functionality of the Java language (the Lang sub-project), and they can provide a Validation framework (Validator) and a database connection pool (Pool). Jakarta Commons can even manipulate XML and Java Beans in a more intuitive and pragmatic fashion.