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<document>
 <header>
  <title>Apache POI™ - Contribution Guidelines</title>
  <authors>
   <person name="Nick Burch" email="dev@poi.apache.org"/>
   <person name="David Fisher" email="dev@poi.apache.org"/>
   </authors>
 </header>

 <body>

 <section><title>Index of Contribution Guidelines</title>
   <ul>
     <li><a href="#Introduction">Introduction</a></li>
     <li><a href="#WhereHelpNeeded">Where is help needed on the project?</a></li>
     <li><a href="#GetInvolved">I just want to get involved, but don't know where to start?</a></li>
     <li><a href="#SubmittingPatches">Submitting Patches</a></li>
     <li><a href="#CodeStyle">Code Style</a></li>
     <li><a href="#Mentoring">Mentoring and Committership</a></li>
     <li><a href="#FileFormatInformation">File Format Information</a></li>
   </ul>
 </section>

 <anchor id="Introduction"/>
 <section><title>Introduction</title>

  <section><title>Disclaimer</title>
   <p>
     Any information in here that might be perceived as legal information is
     informational only.  We're not lawyers, so consult a legal professional
     if needed.
   </p>
  </section>

  <section><title>The Licensing</title>
   <p>
     The POI project is <a href="http://www.opensource.org">OpenSource</a>
     and developed/distributed under the <a
     href="https://www.apache.org/foundation/license-faq.html">
     Apache Software License v2</a>.  Unlike some other licenses, the Apache
     license allows free open source development. Unlike some other Open Source
     licenses, it does not require you to release your source or use any
     particular license for your code which builds on top of it. (There are a
     handful of restrictions, especially around attribution, notices and trademarks,
     so it's worth a read of the license - it isn't scary!).  If you wish to
     contribute to Apache POI (which you're very welcome and encouraged to do so),
     then you must agree to grant your contributions to us under the same license.
   </p>
  </section>
 </section>

 <anchor id="WhereHelpNeeded"/>
 <section><title>Where is help needed on the project?</title>
   <p>There are a lot of open issues in Bugzilla and TODOs in the code. Please see
    the section below for more on these. Get in touch using our mailing lists if you want
    to volunteer.</p>
 </section>

 <anchor id="GetInvolved"/>
 <section><title>I just want to get involved, but don't know where to start?</title>
   <ul>
     <li>Read the rest of the website, understand what POI is and what it does,
         the project vision, etc.</li>
     <li>Use POI a bit, look for gaps in the documentation and examples.</li>
     <li>Join the <a href="site:mailinglists">mailing lists</a> and share your knowledge with others.</li>
     <li>Get <a href="site:subversion">Subversion</a> and check out the POI source tree</li>
     <li>Documentation is always the best place to start contributing, maybe you found that if the documentation just told you how to do X then it would make more sense, modify the documentation.</li>
     <li>Contribute examples - if there's something people are often asking about on the <a href="site:mailinglists">user list</a> which isn't covered in the documentation or current examples, try writing an example of this and uploading it as a patch.</li>
     <li>Get used to building POI, you'll be doing it a lot, be one with the build, know its targets, etc.</li>
     <li>Write Unit Tests.  Great way to understand POI.  Look for classes that aren't tested, or aren't tested on a public/protected method level, start there.</li>
     <li>Download the file format documentation from Microsoft -
       <a href="https://msdn.microsoft.com/en-us/library/cc313105%28v=office.12%29.aspx">OLE2 Binary
       File Formats</a> or
       <a href="https://ecma-international.org/publications-and-standards/standards/ecma-376/">OOXML XML File Formats</a></li>
     <li>Submit patches (see below) of your contributions, modifications.</li>
     <li>Check the <a href="https://issues.apache.org/bugzilla/buglist.cgi?product=POI">bug database</a> for simple problem reports, and write a patch to fix the problem</li>
     <li>Review existing patches in the <a href="http://issues.apache.org/bugzilla/buglist.cgi?product=POI">bug database</a>, and report if they still apply, if they need unit tests atc.</li>
     <li>Take a look at all the <a href="https://issues.apache.org/bugzilla/buglist.cgi?product=POI;bug_status=NEW;bug_status=NEEDINFO">unresolved issues in the bug database</a>, and see if you can help with testing or patches for them</li>
     <li>Add in new features, see <a href="https://issues.apache.org/bugzilla/buglist.cgi?product=POI">Bug database</a> for suggestions.</li>
   </ul>

   <p>The Apache <a href="https://infra.apache.org/contributors.html">Contributors Tech Guide</a> gives a good overview how to start contributing patches.</p>

   <p>The Nutch project also have a very useful guide on becoming a
    new developer in their project. While it is written for their project,
    a large part of it will apply to POI too. You can read it at
    <a href="https://wiki.apache.org/nutch/Becoming_A_Nutch_Developer">http://wiki.apache.org/nutch/Becoming_A_Nutch_Developer</a>. The
    <a href="https://community.apache.org/">Apache Community Development
    Project</a> also provides guidance and mentoring for new contributors.</p>
  </section>

  <anchor id="SubmittingPatches"/>
  <section><title>Submitting Patches</title>
   <p>
     If you use GitHub, you can submit Pull Requests to https://github.com/apache/poi. It is probably
     a good idea to create an issue in the <a href="https://issues.apache.org/bugzilla/buglist.cgi?product=POI">Bug Database</a>
     first and reference it in the PR.
   </p>
   <p>
     For Subversion fans, you can add patch files to the Bugzilla issues at
     <a href="https://issues.apache.org/bugzilla/buglist.cgi?product=POI">Bug Database</a>.
     If there is already a bug-report, attach it there, otherwise create a new bug,
     set the subject to [PATCH] followed by a brief description.
     Explain you patch and any special instructions and submit/save it.
     Next, go back to the bug, and create attachments for the patch files you
     created.  Be sure to describe not only the files purpose, but its format.
     (Is that ZIP or a tgz or a bz2 or what?).
   </p>
   <p>
     Ideally, patches should be submitted early and often. This is for
     two key reasons. Firstly, it's much easier to review smaller patches
     than large ones. This means that smaller patches are much more likely
     to be applied to SVN in a timely fashion. Secondly, by sending in your
     patches earlier rather than later, it's much easier to get feedback
     on your coding and direction. If you've missed an easier way to do something,
     or are duplicating some (probably hidden) existing code, or taking things
     in an unusual direction, it's best to get the feedback sooner rather than
     later! As such, when submitting patches to POI, as with other Apache
     Software Foundation projects, do please try to submit early and often, rather
     than "throwing a large patch over the wall" at the end.
   </p>
   <p>
     A number of Apache projects provide far more comprehensive guides to producing
     and submitting patches than we do, you may wish to review some of their
     information if you're unsure. The
     <a href="https://commons.apache.org/patches.html">Apache Commons</a> one
     is fairly similar as a starting point.
   </p>
  <p>You may create your patch file using either of the following approaches (the committers recommend the first):</p>
  <section><title>Approach 1 - use Ant</title>
  <p>Use Ant to generate a patch file to POI: </p>
   <source>
    ant -f patch.xml
   </source>
  <p>
    This will create a file named <code>patch.tar.gz</code> that will contain a unified diff of files that have been modified
    and also include files that have been added. Review the file for completeness and correctness. This approach
    is recommended because it standardizes the way in which patch files are constructed. It also eliminates the
    chance of you missing to submit new files that constitute part of the patch.
  </p>
  <p>
    To apply a previously generated <code>patch.tar.gz</code> file to a clean subversion checkout, use the following command.
    It will unpack the tarball and add new files to the subversion working copy.
  </p>
   <source>
    ant -f patch.xml apply
   </source>
  </section>
    <section><title>Approach 2 - the manual way</title>
    <p>
      Patches to existing files should be generated with <code>svn diff filename</code> and save the output to a file.
      If you want to get the changes made to multiple files in a directory, just use <code>svn diff</code>.
      then, tar and gzip the patch file as well as any new files that you have added.
    </p>
     <p>If you use a unix shell, you may find the following following
      sequence of commands useful for building the files to attach.</p>
     <source>
  # run this in the root of the checkout, i.e. the directory holding
  #  build.xml and poi.pom

  # build the directory to hold new files
  mkdir /tmp/poi-patch/
  mkdir /tmp/poi-patch/new-files/

  # get changes to existing files
  svn diff > /tmp/poi-patch/diff.txt

  # capture any new files, as svn diff won't include them
  # preserve the path
  svn status | grep "^\?" | awk '{printf "cp --parents %s /tmp/poi-patch/new-files/\n", $2 }' | sh -s

  # tar up the new files
  cd /tmp/poi-patch/new-files/
  tar jcvf ../new-files.tar.bz2
  cd ..

  # upload these to bugzilla
  echo "please upload to bugzilla:"
  echo "   /tmp/poi-patch/diff.txt"
  echo "   /tmp/poi-patch/new-files.tar.bz2"
     </source>
    </section>
    <section><title>Approach 3 - the git way</title>
    <p>
      If you are working on a Git clone of Apache POI (see the
      <a href="site:subversion">Version Control page</a> for
      more on the read-only Git mirrors), it is possible to generate
      a patch of your changes (including new binary files) using Git.
    </p>
    <p>
      For new developers, we'd normally suggest using Subversion and
      one of the methods above, as they tend to be simpler. For people
      who are already proficient with Git, then generating a patch
      from Git can be an easy way to contribute!
    </p>
    <p>
      When generating a patch / patch set from Git, for many related and
      small changes a squashed patch is probably best, as it makes the
      (manual) review quicker. For larger changes, several distinct
      patches are probably best.
    </p>
    <p>
      If you intend to do a noticeable amount of work enhancing Apache POI
      on your own Git repo, we would suggest sending in patches early and
      asking for advice. There's nothing worse than spending a week working
      hard on your own on a change, only to discover you did something on
      Day 1 that isn't acceptable to the project meaning your whole patch
      needs re-doing... Git's offline workflow makes this easier, so try not
      to fall into that trap!
    </p>
    </section>
    <section><title>checklist before submitting a patch</title>
      <ul>
        <li>Added code complies with <a href="#CodeStyle">coding standards</a>.</li>
        <li>Added code compiles and runs on Java 1.8 and preferably newer versions.</li>
        <li>New java files begin with the <a href="https://www.apache.org/foundation/license-faq.html">
             Apache Software License</a> statement.</li>
        <li>The code does not depend on code that is unlicensed or
        <a href="https://www.apache.org/legal/resolved.html#category-a">incompatibly licensed with ASL 2.0</a>.
        <a href="https://www.apache.org/licenses/GPL-compatibility.html">GPL</a> and LGPL code may not be used.</li>
        <li>The code does not include <code>@author</code> tags.</li>
        <li>Existing test cases succeed.</li>
        <li>New test cases written and succeed (Use <code>@Disabled</code> from <code>org.junit</code> for in-progress work).</li>
        <li>Documentation page extended as appropriate.</li>
        <li>Examples updated or added as appropriate.</li>
        <li>Diff files generated using <code>svn diff</code>.</li>
        <li>Newly added files are included in the patch or alongside the patch.</li>
        <li>The <a href="https://bz.apache.org/bugzilla/describecomponents.cgi?product=POI">bugzilla</a> subject dev contains [PATCH], task name and patch reason in subject.</li>
        <li>The bugzilla description contains a rationale for the patch.</li>
        <li>Attachment to the bugzilla entry contains the patch file.</li>
      </ul>
    </section>
  </section>

  <anchor id="CodeStyle"/>
  <section><title>Code Style</title>
    <p>The long standing
      <a href="site:res001">Minimal
      Coding Standards</a> from 2002 still largely apply to the project.</p>
    <p>When making changes to an existing file, please try to follow the
      same style that that file already uses. This will keep things
      looking similar, and will prevent patches becoming largely about
      whitespace. Whitespace fixing changes, if needed, should normally be
      in their own commit, so that they don't crowd out coding changes
      in review.</p>
    <p>Normally, tabs should not be used to indent code. Instead, spaces
      should be used. If starting on a fresh file, please use 4 spaces to
      indent your code. If working on an existing file, please use
      whichever of 3 or 4 spaces that file already follows.</p>
    <p>Normally, braces should open on the same line as the decision
      statement. Braces should normally close on their own line. Brackets
      should normally have a space before them when they are the first.</p>
    <p>Lines normally shouldn't be too long. There's no hard and fast rule,
      but if you line is getting above about 90 characters think about
      splitting it, and you should rarely create something over about 100
      characters without a very good reason!</p>
  </section>

  <anchor id="Mentoring"/>
  <section><title>Mentoring and Committership</title>
   <p>The POI project will generally offer committership to contributors who send
    in consistently good patches over a period of several months.</p>
   <p>The requirement for "good patches" generally means patches which can be applied
    to SVN with little or no changes. These patches should include unit test, and
    appropriate documentation. Whilst your first patch to POI may require quite a
    bit of work before it can be committed by an existing committer, with any luck
    your later patches will be applied with no / minor tweaks. Please do take note
    of any changes required by your earlier patches, to learn for later ones! If
    in doubt, ask on the <a href="site:mailinglists">dev mailing list</a>.</p>
   <p>The requirement for patches over several months is to ensure that committers
    remain with the project. It's very easy for a good developer to fire off half
    a dozen good patches in the couple of weeks that they're working on a POI
    powered project. However, if that developer then moves away, and stops
    contributing to POI after that spurt, then they're not a good candidate for
    committership. As such, we generally require people to stay around for a while,
    submitting patches and helping on the mailing list before considering them
    for committership.</p>
   <p>Where possible, patches should be submitted early and often. For more details
    on this, please see the "Submitting Patches" section above.</p>

   <p>Where possible, the existing developers will try to help and mentor new
    contributors. However, everyone involved in POI is a volunteer, and it may
    happen that your first few patches come in at a time when all the committers
    are very busy. Do please have patience, and remember to use the
    <a href="site:mailinglists">dev mailing list</a> so that other
    contributors can assist you!</p>
   <p>For more information on getting started at Apache, mentoring, and local
    Apache Committers near you who can offer advice, please see the
    <a href="http://community.apache.org/">Apache Community Development
    Project</a> website.</p>
  </section>

 <anchor id="FileFormatInformation"/>
 <section><title>File Format Information</title>
  <section><title>Publicly Available Information on the file formats</title>
  <p>
   In early 2008, Microsoft made a fairly complete set of documentation
   on the binary file formats freely and publicly available. These were
   released under the <a href="https://msdn.microsoft.com/en-us/openspecifications/default">
   Open Specification Promise</a>, which does allow us to use them for
   building open source software under the <a
     href="https://www.apache.org/foundation/license-FAQ.html">
   Apache Software License</a>.
  </p>
  <p>
   You can download the documentation on Excel, Word, PowerPoint and
   Escher (drawing) from
   <a href="https://msdn.microsoft.com/en-us/library/cc313118.aspx">http://msdn.microsoft.com/en-us/library/cc313118.aspx</a>.
   Documentation on a few of the supporting technologies used in these
   file formats can be downloaded from
   <a href="https://msdn.microsoft.com/en-us/library/jj633110.aspx">http://msdn.microsoft.com/en-us/library/jj633110.aspx</a>.
  </p>
  <p>
   For the VSDX format (implemented in Apache POI as XDGF), an
   <a href="https://msdn.microsoft.com/en-us/library/office/jj228622.aspx">introduction
   is available from Microsoft</a>, and full details are available
   <a href="https://msdn.microsoft.com/en-us/library/office/jj684209(v=office.15).aspx">here</a>
   and
   <a href="https://msdn.microsoft.com/en-us/library/hh645006(v=office.12).aspx">here</a>.
  </p>
  <p>
   Previously, Microsoft published a book on the Excel 97 file format.
   It can still be of plenty of use, and is handy dead tree form. Pick up
   a copy of "Excel 97 Developer's Kit" from your favourite second hand
   book store.
  </p>
  <p>
   The newer Office Open XML (ooxml) file formats are documented as part
   of the ECMA / ISO standardisation effort for the formats. This
   documentation is quite large, but you can normally find the bit you
   need without too much effort! This can be downloaded from
   <a href="https://ecma-international.org/publications-and-standards/standards/ecma-376/">https://ecma-international.org/publications-and-standards/standards/ecma-376/</a>,
   and is also under the
   <a href="https://msdn.microsoft.com/en-us/openspecifications/default">OSP</a>.
  </p>
  <p>
   Additionally for the newer Office Open XML (ooxml) file formats, you can
   find some good introductary documentation (often clearer for getting
   started with) at <a href="http://officeopenxml.com/">officeopenxml.com</a>,
   which is an independent site documenting the file formats.
  </p>
  <p>
   It is also worth checking the documentation and code of the other
   open source implementations of the file formats.
  </p>
  </section>
  <section><title>I just signed an NDA to get a spec from Microsoft and I'd like to contribute</title>
   <p>
     In short, stay away, stay far far away.  Implementing these file formats
     in POI is done strictly by using public information. Most of this Public
     Information currently comes from the documentation that Microsoft
     makes freely available (see above). The rest of the public information
     includes sources from other open source projects, books that state the
     purpose intended is for allowing implementation of the file format and
     do not require any non-disclosure agreement and just hard work.
     We are intent on keeping it legal, by contributing patches you agree to
     do the same.
   </p>
   <p>
     If you've ever received information regarding the OLE 2 Compound Document
     Format under any type of exclusionary agreement from Microsoft, or
     received such information from a person bound by such an agreement, you
     cannot participate in this project. Sorry. Well, unless you can persuade
     Microsoft to release you from the terms of the NDA on the grounds that
     most of the information is now publicly available. However, if you have
     been party to a Microsoft NDA, you will need to get clearance from Microsoft
     before contributing.
   </p>
   <p>
     Those submitting patches that show insight into the file format may be
     asked to state explicitly that they have only ever read the publicly
     available file format information, and not any received under an NDA
     or similar, and have only made us of the public documentation.
   </p>
  </section>
 </section>

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<footer>
   <legal>
      Copyright (c) @year@ The Apache Software Foundation. All rights reserved.
      <br />
      Apache POI, POI, Apache, the Apache feather logo, and the Apache
      POI project logo are trademarks of The Apache Software Foundation.
   </legal>
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