Welcome to the Apache Commons
The Commons is an Apache project focused on all aspects of reusable Java components.
The Apache Commons project is composed of three parts:
- The Commons Proper - A repository of reusable Java components.
- The Commons Sandbox - A workspace for Java component development.
- The Commons Dormant - A repository of Sandbox components that are currently inactive.
You may also read our charter, which spells out the goals of the project in greater detail.
The Commons Proper
The Commons Proper is dedicated to one principal goal: creating and maintaining reusable Java components. The Commons Proper is a place for collaboration and sharing, where developers from throughout the Apache community can work together on projects to be shared by the Apache projects and Apache users.
Commons developers will make an effort to ensure that their components have minimal dependencies on other libraries, so that these components can be deployed easily. In addition, Commons components will keep their interfaces as stable as possible, so that Apache users (including other Apache projects) can implement these components without having to worry about changes in the future.
This article gives an overview of (some of) the components which can be found here.
We welcome participation from all that are interested, at all skill levels. Coding, documentation and testing are all critical parts of the software development process. If you are interested in participating in any of these aspects, please join us!
| Components | |
|---|---|
| Attributes | Runtime API to metadata attributes such as doclet tags. |
| BeanUtils | Easy-to-use wrappers around the Java reflection and introspection APIs. |
| Betwixt | Services for mapping JavaBeans to XML documents, and vice versa. |
| Chain | Chain of Responsibility pattern implemention. |
| CLI | Command Line arguments parser. |
| Codec | General encoding/decoding algorithms (for example phonetic, base64, URL). |
| Collections | Extends or augments the Java Collections Framework. |
| Compress | Defines an API for working with tar, zip and bzip2 files. |
| Configuration | Reading of configuration/preferences files in various formats. |
| Daemon | Alternative invocation mechanism for unix-daemon-like java code. |
| DBCP | Database connection pooling services. |
| DbUtils | JDBC helper library. |
| Digester | XML-to-Java-object mapping utility. |
| Discovery | Tools for locating resources by mapping service/reference names to resource names. |
| EL | Interpreter for the Expression Language defined by the JSP 2.0 specification. |
| Library for sending e-mail from Java. | |
| Exec | API for dealing with external process execution and environment management in Java. |
| FileUpload | File upload capability for your servlets and web applications. |
| IO | Collection of I/O utilities. |
| JCI | Java Compiler Interface |
| Jelly | XML based scripting and processing engine. |
| Jexl | Expression language which extends the Expression Language of the JSTL. |
| JXPath | Utilities for manipulating Java Beans using the XPath syntax. |
| Lang | Provides extra functionality for classes in java.lang. |
| Launcher | Cross platform Java application launcher. |
| Logging | Wrapper around a variety of logging API implementations. |
| Math | Lightweight, self-contained mathematics and statistics components. |
| Modeler | Mechanisms to create Model MBeans compatible with JMX specification. |
| Net | Collection of network utilities and protocol implementations. |
| Pool | Generic object pooling component. |
| Primitives | Smaller, faster and easier to work with types supporting Java primitive types. |
| Proxy | Library for creating dynamic proxies. |
| Sanselan | A pure-Java image library. |
| SCXML | An implementation of the State Chart XML specification aimed at creating and maintaining a Java SCXML engine. It is capable of executing a state machine defined using a SCXML document, and abstracts out the environment interfaces. |
| Transaction | Implementations for multi level locks, transactional collections and transactional file access. |
| Validator | Framework to define validators and validation rules in an xml file. |
| VFS | Virtual File System component for treating files, FTP, SMB, ZIP and such like as a single logical file system. |
The Commons Sandbox
This project also contains a workspace that is open to all Apache committers. It's a place to try out new ideas and prepare for inclusion into the Commons portion of the project or into another Apache 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.
See here for Sandbox components.
The Commons Dormant
These are Commons Sandbox components that have been deemed inactive since they have seen little recent development activity. If you wish to use any of these components, you must build them yourselves. It is best to assume that these components will not be released in the near future.
See here for Dormant components.
Where do I get releases?
The individual components have independent releases. Some releases for some components may be available only through the mirroring system. Some releases for some components (typically the older ones) are not available through the mirroring system.
See the individual websites listed above for the specific downloads, or use the Releases menu option.
How do I contribute, give feedback, fix bugs and so on?
The Commons project really needs and appreciates any contributions, including documentation help, source code and feedback.
- Discussion occurs on the Commons mailing list.
- Access to the SVN commons/proper repository is available both online and with a svn client.
- Access to the SVN commons/sandbox repository is available both online and with a svn client.
- Access to the SVN commons/dormant repository is available both online and with a svn client.
Related Components @Apache
The Commons HttpClient project used to be a part of Commons, but is now part of Apache HttpComponents - see Jakarta Commons HttpClient
Some other Apache Projects also have commons subprojects:
So, if you can't find what you need here, you might like to take a look there. Some components which started out here have migrated to these other places.