This document is meant for Apache contributors. A contributor is anyone who wants contribute (code, documentation, tests, ideas, anything!) to any Apache project hosted here at the Apache Software Foundation (ASF). Note: if you are interested in contributing financially, please see the ASF Foundation contribution page.

Existing Apache Committers should see the New Committer Guide and FAQ.

How Open Source Works

Several books and many papers have been written about the way open source works and how you can become a valuable member of the open source/free software community. For an overview of how it works at Apache, see the ASF front page , the ASF How it works document, the Apache Jakarta: Understanding Opensource document, the FSF website , the Open Source Initiative Website , the The Cathedral and the Bazaar paper and Google.

Getting sources from revision control (SVN or git)

Subversion (SVN), is the version control system used by most projects at Apache. See The Subversion Homepage for more about SVN. Some Apache projects use git instead.

Bleeding-edge / Nightly code

Getting the source directly from the source repository usually gives you the bleeding edge version of that particular project. To be more precise, in the Subversion repository, there are usually three separate top-level directories: trunk , tags and branches.

The trunk directory contains the current source code, and thus it's usually used in the source code access urls given by the projects.

The tags directory contains specific versions of the project that were tagged with some name. These were created for some specific reason. For instance, you usually find a tag for each released version of the project.

The branches directory finally contains versions of the project that are different in some respect, such as experimental versions, or former released versions.

In short, if you are looking to download the source code for stable versions of the ASF projects, you should go to a normal mirror site and simply download it from there. Only if you want the bleeding edge source (from the trunk folder, or if you need an older version for which you don't get the source code from the mirrors anymore, use the source repository.

Before you start using source code from the source repository, you need to check out a local copy of the remote repository. Here's how. Subversion, which is the technology/tool used by Apache to maintain the source repository, is an open source project hosted by Apache. You will find most tools noted here on this site or related sites at Tigris the previous home of Subversion. So, if your system is not listed here, please go to Tigris and see what options are available to you.

For more details about the Subversion client, the Subversion book is the place to start.

Windows: Use cygwin

Cygwin is a free software suite of ports of popular Linux tools and utilities to run natively under windows. Among it is a port of the svn application which is the Subversion client required for checking out source code from the Apache source repositories.

If you use cygwin, please follow the Unix/Linux instructions below.

Windows: Use the command-line tools

The Subversion utilities are available as native Windows binaries. Get them from the Subversion homepage. To use these tools, open a command window (click Start > Run..., then type 'cmd'), then enter the following commands:

(Note: you can use any directory in place of C:\checkout. Replace %SVNUTILS% with where you installed the svn binary, e.g. with, C:\svn-win32-1.3.2\bin, or with nothing if you added the SVN utility to your PATH.)

mkdir C:\checkout
cd /D C:\checkout
%SVNUTILS%\svn.exe svn checkout ^
    http://svn.apache.org/repos/asf/infrastructure/site/trunk/ site

This will checkout the ASF website into a sub-directory called site. The checkout will take a while, depending on your connection. Go ahead and grab yourself a coffee or ten. When done, you should have checked out the sources for the website you're reading now (unfortunately it won't suffice for actually re-creating it, you'll also need Apache Ant , which you should go install right now if you haven't already). Yes, you can enter these URLs into a browser and actually look at the sources before checking out anything. However, for this you should probably use the Web view at http://svn.apache.org/viewvc/ as it is much nicer to use than the raw view.The above URL gives you read-only access. If you're a committer, then you should use instead svn checkout --username [username] https://.... The https access requires authentication and allows you to commit your changes.

Windows: Use TortoiseSVN

TortoiseSVN is a neat extension for the Windows Explorer which integrates SVN. Using it is real simple:

After you've created a folder where you want to check out the sources to, right-click and select SVN Checkout... :

screenshot of SVN checkout

Then, fill out the settings like in the screenshot below, and then click ok.

screenshot of SVN settings

This checks out the source of the site that you're looking at.

Linux: Use the command-line tools

The Subversion utilities are available as native Unix and Linux binaries. Chances are you already have them installed. Try it by opening a console and typing 'svn'. If you get an error along the lines of "bash: svn: command not found", then you need to install them first. How you do that, depends on what Unix or Linux you have. For instance, with Debian or Ubuntu, you can do so by opening a console window and entering the commands:

su -
# enter the root password when prompted
apt-get update
apt-get install svn
exit

Other systems have graphical installers or use the rpm tool. Please refer to the documentation of your system for instructions on how to install software

Once you have these tools installed, open a command window, then enter the following commands:

# you can use any directory in place of ~/checkout
mkdir ~/checkout
cd ~/checkout
svn checkout http://svn.apache.org/repos/asf/infrastructure/site/trunk/ site

This will checkout this very documentation that you're reading, into a sub-directory called site. Note that depending on your connection this will take a while.

IDE/Editors: Using an IDE for source repository access

Most decent IDEs these days provide Subversion integration. See the IDE Developer's Guide if you need information on how to configure your IDE (note this is a java-centric paper).

For Java IDEs, you might have to install a plugin in order to get SVN support:

IDE Plugin/Extension
Eclipse Subclipse
JetBrains IDEA before version 5 svn-up
NetBeans Subversion profile

Please refer to the documentation of the IDE and the plugin/extension for how to install and use the plugin/extension.

How to update your checked-out module

You don't need to check out a entire module every time something is changed. To synchronize your local copy with the remote repository, you use the svn update which goes like this:

# location where the module is stored
cd checkout

# either you call the update in the module's directory
# or you supply the list of modules to update, like this
svn update site

With graphical clients, the process is similar. For example, in TortoiseSVN you can right-click on any subversion checkout directory, and select the "SVN Update" option

How to Provide feedback to Apache projects

A valuable way to contribute to ASF projects is by using the software, and then providing feedback about them to its developers. Different software projects have different preferences about how you should go around to submitting feedback. Check out the project website for more information. In absence of information on how to provide feedback on a project's website, follow these guidelines.

A vital part of the ASF projects are the project mailing lists. Most have a users list named users@${project}.apache.org or user@${project}.apache.org. Subscribe to it by sending an e-mail to users-subscribe@${project}.apache.org, then follow the instructions. Be sure to follow netiquette and be nice to the developers.

Then, tell the developer and user community about your use of the software product, your experiences in setting it up, issues you encountered, stuff like that. Your story will likely be very welcome if well-written and you Read The Manual before doing anything silly, and you'll probably receive some enthusiastic response from some of the developers and other users (if not, don't worry. They're probably just busy with other things). If you found specific issues or have a specific idea about how things should work, you'll likely be asked to submit a bug report or patch to improve things

Note that many projects also have a developer-focused mailing list named dev@${project}.apache.org where technical project details are discussed.

Sending in a Bug Report

We take bugs very seriously. To help us to quickly fix the bug, be sure to include as much information with your report as possible such as your platform, version numbers, error logs, configuration, etc. When you are not sure whether a piece of information is relevant, include it.

To submit a bug report, first make sure the bug hasn't been reported before, fixed in a newer version of the software, or fixed in the current development version. Then file a report. Different projects have different preferences for this. Usually you are asked to enter the bug into a bug tracking database, which is normally either Bugzilla, or Jira. Some projects don't use an issue tracker. In that case, send the bug report to the appropriate mailing list.

If you have the knowledge to supply a patch that fixes the issue, please do so...

Note most issue trackers also support placing requests for enhancements in the database. Feel free to do so. Make sure to set the appropriate flags in the issue tracker to indicate that your request is not about a bug.

When your bug report is not addressed, try and submit a patch for it. It'll increase the chances of the bug getting fixed.

Sending in Patches

A patch is a computer-generated file that describes differences between different versions of one or more sourcefiles. Once again, different software projects have different preferences about how you should go around to submitting patches. Check out the project website for more information. In absence of information on how to provide feedback on any specific Apache project's own website, follow these guidelines. For an example, see the Apache Subversion project's patch guide.

Patches are generated using the unix utility diff or the svn diff command. They can be applied using the unix utility patch. When you want to contribute a change or addition to existing sourcecode, you should:

  • check out the latest copy of the sources from SVN (see above)

  • change the sourcefiles to incorporate your change or addition. Make sure you also provide appropriate source code documentation (like javadoc for java sources), and follow a project's coding conventions.

  • check the software still compiles and runs correctly

  • run any unit or regression tests the software may have

If this works, you can create your patch. Remove all build products and remnants from the module tree (like any 'build', 'dist' or 'bin' directories), then build the actual patch. Here's how to do it using the commandline SVN client under unix: Apache projects prefer the unified diff format. The subversion tool creates that automatically. If you use other tools, please refer to their documentation for details on set the diff format.

# location where the modules are stored
cd checkout

# directory of the module
cd site

# creation of the diff
svn diff > site.patch

The Subversion client now examines all subdirectories for changed files, then compares the changed file to the one on the server. It generates the patch. The '>' redirection results in the resulting patch being put in a textfile named (in this case) site.patch.

With your patch generated, you need to send it to the developers. Different projects have different preferences for this. Usually you are asked to add it as an attachment to the relevant bug report in the bug tracking database, which is normally either Bugzilla or Jira depending on the project. If a bug report doesn't exist yet, create one. A very few projects don't use an issue tracker. In that case, send the patch as an attachment to an e-mail with a subject prefixed with "[PATCH]". Patches should be sent to the appropriate development mailing list. If the patch is large, please ask before e-mailing it in case there is a better way to provide it.

You should supply a patch-per-issue, that is, a patch can span multiple files but you should normally try not to fix multiple bugs in a single patch, unless those bugs are intimately related.

Please show some patience with the developers if your patch is not applied as fast as you'd like or a developer asks you to make changes to the patch. If you do not receive any feedback in a reasonable amount of time (say a week or two), feel free to send a follow-up e-mail to the developer list. Open Source developers are all volunteers, often doing the development in their spare time.

Patching Project Websites

One of the simplest ways to contribute to Apache projects is by suggesting improvements to project websites. If something on the website doesn't make sense to you, or if you have a better way to explain something, send the project a patch!

Most Apache project websites use our own custom Apache CMS system to both edit, manage, and build the websites. We have a guide for how to submit website patches for non-committers you should read.

The Apache CMS system lets you install a bookmark in your web browser that lets you directly edit most Apache web pages in a simple browser-based editor. Then you can submit your patch to the web page to the project directly, where a committer can check it in and update the website.