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<!DOCTYPE document [
  <!ENTITY project SYSTEM "project.xml">
]>
<document>

    &project;

    <properties>
      <title>Building Tomcat</title>
    </properties>

<body>

<section name="Table of Contents">
<toc/>
</section>

<section name="Introduction">

<p>
Building Apache Tomcat from source is very easy, and is the first step to
contributing to Tomcat. The complete and comprehensive instructions are
provided in the file <a href="BUILDING.txt">BUILDING.txt</a>.
The following is a quick step by step guide.
</p>

</section>

<section name="Download a Java Development Kit (JDK) version 11 or later">

<p>
Building Apache Tomcat requires a JDK (version 11) or later to be installed. You
can download one from
<a href="https://adoptium.net/temurin/releases">https://adoptium.net/temurin/releases</a>
or another JDK vendor.
</p>

<p>
<b>IMPORTANT</b>: Set an environment variable JAVA_HOME to the pathname of the
directory into which you installed the JDK release.
</p>

</section>

<section name="Install Apache Ant 1.9.10 or later">

<p>
Download a binary distribution of Ant 1.9.10 or later from
<a href="https://ant.apache.org/bindownload.cgi">here</a>.
</p>

<p>
Unpack the binary distribution into a convenient location so that the
Ant release resides in its own directory (conventionally named
<code>apache-ant-1.9.x</code>).  For the remainder of this guide,
the symbolic name <code>${ant.home}</code> is used to refer to the full pathname of
 the Ant installation directory.
</p>

<p>
<b>IMPORTANT</b>: Create an ANT_HOME environment variable to point the directory <code>${ant.home}</code>,
and modify the PATH environment variable to include directory
<code>${ant.home}/bin</code> in its list.  This makes the <code>ant</code> command line script
available, which will be used to actually perform the build.
</p>

</section>

<section name="Obtain the Tomcat source code">

  <p>
  Tomcat Git repository URL:
  <a href="https://github.com/apache/tomcat">https://github.com/apache/tomcat</a>
  </p>
  <p>
  Tomcat source packages:
  <download>https://tomcat.apache.org/download-<version-major/>0.cgi</download>.
  </p>

  <p>
  Clone the source repository using Git, selecting a tag for released version or
  main for the current development code, or download and unpack a
  source package. For the remainder of this guide, the symbolic name
  <code>${tomcat.source}</code> is used to refer to the
  location where the source has been placed.
  </p>

</section>

<section name="Configure download area">

<p>
  Building Tomcat involves downloading a number of libraries that it depends on.
  It is strongly recommended to configure download area for those libraries.
</p>

<p>
  By default the build is configured to download the dependencies into the
  <code>${user.home}/tomcat-build-libs</code> directory. You can change this
  (see below) but it must be an absolute path.
</p>

<p>
  The build is controlled by creating a
  <code>${tomcat.source}/build.properties</code> file. It can be used to
  redefine any property that is present in <code>build.properties.default</code>
  and <code>build.xml</code> files. The <code>build.properties</code> file
  does not exist by default. You have to create it.
</p>

<p>
  The download area is defined by property <code>base.path</code>. For example:
</p>

<source><![CDATA[# ----- Default Base Path for Dependent Packages -----
# Replace this path with the directory path where
# dependencies binaries should be downloaded.
base.path=/home/me/some-place-to-download-to]]></source>

<p>
  Different versions of Tomcat are allowed to share the same download area.
</p>

<p>
  Another example:
</p>

<source>base.path=${user.dir}/../libraries-tomcat<version-major-minor/></source>

<p>
  Users who access the Internet through a proxy must use the properties
  file to indicate to Ant the proxy configuration:
</p>

<source><![CDATA[# ----- Proxy setup -----
proxy.host=proxy.domain
proxy.port=8080
proxy.use=on]]></source>

</section>

<section name="Building Tomcat">

<p>
Use the following commands to build Tomcat:
</p>

<p>
<code>cd ${tomcat.source}</code><br/>
<code>ant</code>
</p>

<p>
Once the build has completed successfully, a usable Tomcat installation will have been
produced in the <code>${tomcat.source}/output/build</code> directory, and can be started
and stopped with the usual scripts.
</p>
</section>

<section name="Building with Eclipse">

<p>
<b>IMPORTANT:</b> This is not a supported means of building Tomcat; this information is
provided without warranty :-).
The only supported means of building Tomcat is with the Ant build described above.
However, some developers like to work on Java code with a Java IDE,
and the following steps have been used by some developers.
</p>

<p>
<b>NOTE:</b> This will not let you build everything under Eclipse;
the build process requires use of Ant for the many stages that aren't
simple Java compilations.
However, it will allow you to view and edit the Java code,
get warnings, reformat code, perform refactorings, run Tomcat
under the IDE, and so on.
</p>

<p>
<b>WARNING:</b> Do not forget to create and configure
  <code>${tomcat.source}/build.properties</code> file as described above
  before running any Ant targets.
</p>

<p>
Sample Eclipse project files and launch targets are provided in the
<code>res/ide-support/eclipse</code> directory of the source tree.
The instructions below will automatically copy these into the required locations.
</p>
<p>
An Ant target is provided as a convenience to download all binary dependencies, and to create
the Eclipse project and classpath files in the root of the source tree.
</p>

<p>
<code>cd ${tomcat.source}</code><br/>
<code>ant ide-eclipse</code>
</p>

<p>
Start Eclipse and create a new Workspace.
</p>

<p>
Open the <em>Preferences</em> dialog and then select <em>Java-&gt;Build Path-&gt;Classpath
Variables</em> to add two new <em>Classpath Variables</em>:
</p>


<table class="defaultTable">
 <tr><td>TOMCAT_LIBS_BASE</td><td>The same location as the <code>base.path</code>
  setting in <code>build.properties</code>, where the binary dependencies have been downloaded</td></tr>
 <tr><td>ANT_HOME</td><td>the base path of Ant 1.9.10 or later</td></tr>
</table>


<p>
Use <em>File-&gt;Import</em> and choose <em>Existing Projects into Workspace</em>.
From there choose the root directory of the Tomcat source tree (<code>${tomcat.source}</code>)
and import the Tomcat project located there.
</p>

<p>
<code>start-tomcat</code> and <code>stop-tomcat</code> launch configurations are provided in
<code>res/ide-support/eclipse</code> and will be available in the <em>Run-&gt;Run Configurations</em>
dialog. Use these to start and stop Tomcat from Eclipse.
If you want to configure these yourself (or are using a different IDE)
then use <code>org.apache.catalina.startup.Bootstrap</code> as the main class,
<code>start</code>/<code>stop</code> etc. as program arguments, and specify <code>-Dcatalina.home=...</code>
(with the name of your build directory) as VM arguments.
</p>

<p>
Tweaking a few formatting preferences will make it much easier to keep consistent with Tomcat
coding conventions (and have your contributions accepted):
</p>

<table class="defaultTable">
  <tr><td>Java -&gt; Code Style -> Formatter -&gt; Edit...</td>
  <td>Tab policy: Spaces only<br/>Tab and Indentation size: 4</td></tr>
  <tr><td>General -&gt; Editors -> Text Editors</td>
  <td>Displayed tab width: 2<br/>Insert spaces for tabs<br/>Show whitespace characters (optional)</td></tr>
  <tr><td>XML -&gt; XML Files -> Editor</td><td>Indent using spaces<br/>Indentation size: 2</td></tr>
  <tr><td>Ant -&gt; Editor -> Formatter</td><td>Tab size: 2<br/>Use tab character instead of spaces: unchecked</td></tr>
</table>

<p>
The recommended configuration of Compiler Warnings is documented in
<code>res/ide-support/eclipse/java-compiler-errors-warnings.txt</code> file.
</p>

</section>

<section name="Building with other IDEs">
<p>
The same general approach should work for most IDEs; it has been reported
to work in IntelliJ IDEA, for example.
</p>

</section>

</body>
</document>
