Commons VFS provides a single API for accessing various different file systems. It presents a uniform view of the files from various different sources, such as the files on local disk, on an HTTP server, or inside a Zip archive.

Although the java.net package provides basic functionality for accessing resources via HTTP, it doesn't provide the full flexibility or functionality needed by many applications. HttpClient seeks to fill this void by providing an efficient, up-to-date, and feature-rich package implementing the client side of the most recent HTTP standards and recommendations.

Java Compiler Compiler (JavaCC) is the most popular parser generator for use with Java applications. A parser generator is a tool that reads a grammar specification and converts it to a Java program that can recognize matches to the grammar. In addition to the parser generator itself, JavaCC provides other standard capabilities related to parser generation such as tree building (via a tool called JJTree included with JavaCC), actions, debugging, etc.

JMock is a library that supports test-driven development of Java code with mock objects. Mock objects help you design and test the interactions between the objects in your programs.

The jMock library

• makes it quick and easy to define mock objects

• lets you precisely specify the interactions between your objects, reducing the brittleness of your tests

• plugs into your favourite test framework

• is easy to extend.

This package provides a library of matcher objects (also known as constraints or predicates) allowing match rules to be defined declaratively, to be used in other frameworks. Typical scenarios include testing frameworks, mocking libraries and UI validation rules.

The Logging package is a thin bridge between different logging implementations. A library that uses the commons-logging API can be used with any logging implementation at runtime.

TestNG is a testing framework inspired from JUnit and NUnit but introducing some new functionalities that make it more powerful and easier to use.

Bnd is a swiss army knife for OSGi, it creates manifest headers based on analyzing the class code, it verifies the project settings, it manages project dependencies, gives diffs jars, and much more.

APT stands for Annotation Processing Tool. APT provides a means for generating files and compiling new Java classes based on annotations found in your source code.

Sisu is a modular JSR330-based container that supports classpath scanning, auto-binding, and dynamic auto-wiring. This package adds Plexus support to the Sisu-Inject container.

JOpt Simple is a Java library for parsing command line options, such as those you might pass to an invocation of javac. In the interest of striving for simplicity, as closely as possible JOpt Simple attempts to honor the command line option syntaxes of POSIX getopt and GNU getopt_long. It also aims to make option parser configuration and retrieval of options and their arguments simple and expressive, without being overly clever.

OSGi, for Open Services Gateway initiative framework, is a module system and service platform for the Java programming language. This package contains an interface and utilitary classes for promises. A Promise represents a future value. It handles the interactions for asynchronous processing.

Stax2 API is an extension to basic Stax 1.0 API that adds significant new functionalities, such as full-featured bi-direction validation interface and high-performance Typed Access API.

This is a word-aligned compressed variant of the Java Bitset class. It provides both a 64-bit and a 32-bit RLE-like compression scheme. It can be used to implement bitmap indexes.

The goal of word-aligned compression is not to achieve the best compression, but rather to improve query processing time. Hence, JavaEWAH tries to save CPU cycles, maybe at the expense of storage. However, the EWAH scheme is always more efficient storage-wise than an uncompressed bitmap (as implemented in the BitSet class by Sun).

This package provides the Eclipse core expression language with the org.eclipse.core.expressions module.

Eclipse LSP4J provides Java bindings for the Language Server Protocol and the Debug Adapter Protocol. This package contains its LSP4J Java bindings for the Debug Server Protocol.

OPS4J stands for Open Participation Software for Java. This package contains utilities for obtaining services via the Java SE 6 ServiceLoader.

The AOP Alliance project is a joint project between several software engineering people who are interested in Aspect-Oriented Programming (AOP) and Java.

Tinybundles is all about creating OSGi related artifacts like Bundles, Fragments and Deployment Packages with Java Api. It is very convenient to create such artifacts on-the-fly inside Tests (like in Pax Exam). On the other hand, this library can be a foundation of real end user tools that need to create those artifacts.

TreeLayout creates tree layouts for arbitrary trees. It is not restricted to a specific output or format, but can be used for any kind of two dimensional diagram. Examples are Swing based components, SVG files, etc. This is possible because TreeLayout separates the layout of a tree from the actual rendering.

Commons CSV reads and writes files in variations of the Comma Separated Value (CSV) format. The most common CSV formats are predefined in the CSVFormat class:

• Microsoft Excel

• Informix UNLOAD

• Informix UNLOAD CSV

• MySQL

• RFC 4180

• TDF

Custom formats can be created using a fluent style API.

Xbean-reflect provides very flexible ways to create objects and graphs of objects for dependency injection frameworks

LMAX Disruptor is a software pattern and software component for high performance inter-thread communication that avoids the need for message queues or resource locking.

This library supplies some utility classes needed for libraries from the SIS division at ETH Zurich like jHDF5.