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284 lines
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<html><head><META http-equiv="Content-Type" content="text/html; charset=iso-8859-1"><title>Application Developer's Guide - Source Organization</title><meta name="author" value="Craig R. McClanahan"><meta name="email" value="craigmcc@apache.org"></head><body bgcolor="#ffffff" text="#000000" link="#525D76" alink="#525D76" vlink="#525D76"><table border="0" width="100%" cellspacing="0"><!--PAGE HEADER--><tr><td><!--PROJECT LOGO--><a href="http://tomcat.apache.org/"><img src="../../images/tomcat.gif" align="right" alt="
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The Apache Tomcat Servlet/JSP Container
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" border="0"></a></td><td><font face="arial,helvetica,sanserif"><h1>Apache Tomcat 6.0</h1></font></td><td><!--APACHE LOGO--><a href="http://www.apache.org/"><img src="../../images/asf-logo.gif" align="right" alt="Apache Logo" border="0"></a></td></tr></table><table border="0" width="100%" cellspacing="4"><!--HEADER SEPARATOR--><tr><td colspan="2"><hr noshade="noshade" size="1"></td></tr><tr><!--RIGHT SIDE MAIN BODY--><td width="80%" valign="top" align="left"><table border="0" width="100%" cellspacing="4"><tr><td align="left" valign="top"><h1>Application Developer's Guide</h1><h2>Source Organization</h2></td><td align="right" valign="top" nowrap="true"><img src="../../images/void.gif" width="1" height="1" vspace="0" hspace="0" border="0"></td></tr></table><table border="0" cellspacing="0" cellpadding="2"><tr><td bgcolor="#525D76"><font color="#ffffff" face="arial,helvetica.sanserif"><a name="Directory Structure"><strong>Directory Structure</strong></a></font></td></tr><tr><td><blockquote>
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<blockquote><em>
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<p>The description below uses the variable name $CATALINA_HOME
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to refer to the directory into which you have installed Tomcat 5,
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and is the base directory against which most relative paths are
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resolved. However, if you have configured Tomcat 5 for multiple
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instances by setting a CATALINA_BASE directory, you should use
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$CATALINA_BASE instead of $CATALINA_HOME for each of these
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references.</p>
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</em></blockquote>
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<p>A key recommendation of this manual is to separate the directory
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hierarchy containing your source code (described in this section) from
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the directory hierarchy containing your deployable application
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(described in the preceding section). Maintaining this separation has
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the following advantages:</p>
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<ul>
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<li>The contents of the source directories can be more easily administered,
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moved, and backed up if the "executable" version of the application
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is not intermixed.
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<br><br></li>
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<li>Source code control is easier to manage on directories that contain
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only source files.
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<br><br></li>
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<li>The files that make up an installable distribution of your
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application are much easier to select when the deployment
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hierarchy is separate.</li>
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</ul>
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<p>As we will see, the <code>ant</code> development tool makes the creation
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and processing of such directory hierarchies nearly painless.</p>
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<p>The actual directory and file hierarchy used to contain the source code
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of an application can be pretty much anything you like. However, the
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following organization has proven to be quite generally applicable, and is
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expected by the example <code>build.xml</code> configuration file that
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is discussed below. All of these components exist under a top level
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<em>project source directory</em> for your application:</p>
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<ul>
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<li><strong>docs/</strong> - Documentation for your application, in whatever
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format your development team is using.<br><br></li>
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<li><strong>src/</strong> - Java source files that generate the servlets,
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beans, and other Java classes that are unique to your application.
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If your source code is organized in packages (<strong>highly</strong>
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recommended), the package hierarchy should be reflected as a directory
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structure underneath this directory.<br><br></li>
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<li><strong>web/</strong> - The static content of your web site (HTML pages,
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JSP pages, JavaScript files, CSS stylesheet files, and images) that will
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be accessible to application clients. This directory will be the
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<em>document root</em> of your web application, and any subdirectory
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structure found here will be reflected in the request URIs required to
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access those files.<br><br></li>
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<li><strong>web/WEB-INF/</strong> - The special configuration files required
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for your application, including the web application deployment descriptor
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(<code>web.xml</code>, defined in the
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<a href="http://java.sun.com/products/servlet">Servlet Specification</a>),
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tag library descriptors for custom tag libraries
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you have created, and other resource files you wish to include within
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your web application. Even though this directory appears to be a
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subdirectory of your <em>document root</em>, the Servlet Specification
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prohibits serving the contents of this directory (or any file it contains)
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directly to a client request. Therefore, this is a good place to store
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configuration information that is sensitive (such as database connection
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usernames and passwords), but is required for your application to
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operate successfully.</li>
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</ul>
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<p>During the development process, two additional directories will be
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created on a temporary basis:</p>
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<ul>
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<li><strong>build/</strong> - When you execute a default build
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(<code>ant</code>), this directory will contain an exact image
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of the files in the web application archive for this application.
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Tomcat 5 allows you to deploy an application in an unpacked
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directory like this, either by copying it to the
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<code>$CATALINA_HOME/webapps</code> directory, or by <em>installing</em>
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it via the "Manager" web application. The latter approach is very
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useful during development, and will be illustrated below.
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<br><br></li>
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<li><strong>dist/</strong> - When you execute the <code>ant dist</code>
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target, this directory will be created. It will create an exact image
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of the binary distribution for your web application, including an license
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information, documentation, and README files that you have prepared.</li>
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</ul>
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<p>Note that these two directories should <strong>NOT</strong> be archived in
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your source code control system, because they are deleted and recreated (from
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scratch) as needed during development. For that reason, you should not edit
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any source files in these directories if you want to maintain a permanent
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record of the changes, because the changes will be lost the next time that a
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build is performed.</p>
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<table border="0" cellspacing="0" cellpadding="2"><tr><td bgcolor="#828DA6"><font color="#ffffff" face="arial,helvetica.sanserif"><a name="External Dependencies"><strong>External Dependencies</strong></a></font></td></tr><tr><td><blockquote>
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<p>What do you do if your application requires JAR files (or other
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resources) from external projects or packages? A common example is that
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you need to include a JDBC driver in your web application, in order to
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operate.</p>
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<p>Different developers take different approaches to this problem.
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Some will encourage checking a copy of the JAR files you depend on into
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the source code control archives for every application that requires those
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JAR files. However, this can cause significant management issues when you
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use the same JAR in many applications - particular when faced with a need
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to upgrade to a different version of that JAR file.</p>
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<p>Therefore, this manual recommends that you <strong>NOT</strong> store
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a copy of the packages you depend on inside the source control archives
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of your applications. Instead, the external dependencies should be
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integrated as part of the process of <strong>building</strong> your
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application. In that way, you can always pick up the appropriate version
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of the JAR files from wherever your development system administrator has
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installed them, without having to worry about updating your application
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every time the version of the dependent JAR file is changed.</p>
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<p>In the example Ant <code>build.xml</code> file, we will demonstrate
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how to define <em>build properties</em> that let you configure the locations
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of the files to be copied, without having to modify <code>build.xml</code>
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when these files change. The build properties used by a particular
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developer can be customized on a per-application basis, or defaulted to
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"standard" build properties stored in the developer's home directory.</p>
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<p>In many cases, your development system administrator will have already
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installed the required JAR files into Tomcat 5's <code>common/lib</code>
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or <code>shared/lib</code> directories. If this has been done, you need
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to take no actions at all - the example <code>build.xml</code> file
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automatically constructs a compile classpath that includes these files.</p>
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</blockquote></td></tr></table>
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</blockquote></td></tr></table><table border="0" cellspacing="0" cellpadding="2"><tr><td bgcolor="#525D76"><font color="#ffffff" face="arial,helvetica.sanserif"><a name="Source Code Control"><strong>Source Code Control</strong></a></font></td></tr><tr><td><blockquote>
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<p>As mentioned earlier, it is highly recommended that you place all of the
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source files that comprise your application under the management of a
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source code control system like the Concurrent Version System (CVS). If you
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elect to do this, every directory and file in the source hierarchy should be
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registered and saved -- but none of the generated files. If you register
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binary format files (such as images or JAR libraries), be sure to indicate
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this to your source code control system.</p>
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<p>We recommended (in the previous section) that you should not store the
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contents of the <code>build/</code> and <code>dist/</code> directories
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created by your development process in the source code control system. An
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easy way to tell CVS to ignore these directories is to create a file named
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<code>.cvsignore</code> (note the leading period) in your top-level source
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directory, with the following contents:</p>
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<div align="left"><table cellspacing="4" cellpadding="0" border="0"><tr><td bgcolor="#023264" width="1" height="1"><img src="../../images/void.gif" width="1" height="1" vspace="0" hspace="0" border="0"></td><td bgcolor="#023264" height="1"><img src="../../images/void.gif" width="1" height="1" vspace="0" hspace="0" border="0"></td><td bgcolor="#023264" width="1" height="1"><img src="../../images/void.gif" width="1" height="1" vspace="0" hspace="0" border="0"></td></tr><tr><td bgcolor="#023264" width="1"><img src="../../images/void.gif" width="1" height="1" vspace="0" hspace="0" border="0"></td><td bgcolor="#ffffff" height="1"><pre>
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build
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dist
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build.properties
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</pre></td><td bgcolor="#023264" width="1"><img src="../../images/void.gif" width="1" height="1" vspace="0" hspace="0" border="0"></td></tr><tr><td bgcolor="#023264" width="1" height="1"><img src="../../images/void.gif" width="1" height="1" vspace="0" hspace="0" border="0"></td><td bgcolor="#023264" height="1"><img src="../../images/void.gif" width="1" height="1" vspace="0" hspace="0" border="0"></td><td bgcolor="#023264" width="1" height="1"><img src="../../images/void.gif" width="1" height="1" vspace="0" hspace="0" border="0"></td></tr></table></div>
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<p>The reason for mentioning <code>build.properties</code> here will be
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explained in the <a href="processes.html">Processes</a> section.</p>
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<p>Detailed instructions for your source code control environment are beyond
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the scope of this manual. However, the following steps are followed when
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using a command-line CVS client:</p>
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<ul>
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<li>To refresh the state of your source code to that stored in the
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the source repository, go to your project source directory, and
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execute <code>cvs update -dP</code>.
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<br><br></li>
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<li>When you create a new subdirectory in the source code hierarchy, register
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it in CVS with a command like <code>cvs add {subdirname}</code>.
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<br><br></li>
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<li>When you first create a new source code file, navigate to the directory
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that contains it, and register the new file with a command like
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<code>cvs add {filename}</code>.
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<br><br></li>
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<li>If you no longer need a particular source code file, navigate to the
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containing directory and remove the file. Then, deregister it in CVS
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with a command like <code>cvs remove {filename}</code>.
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<br><br></li>
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<li>While you are creating, modifying, and deleting source files, changes
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are not yet reflected in the server repository. To save your changes in
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their current state, go to the project source directory
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and execute <code>cvs commit</code>. You will be asked to write a brief
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description of the changes you have just completed, which will be stored
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with the new version of any updated source file.</li>
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</ul>
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<p>CVS, like other source code control systems, has many additional features
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(such as the ability to tag the files that made up a particular release, and
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support for multiple development branches that can later be merged). See the
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links and references in the <a href="introduction.html">Introduction</a> for
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more information.</p>
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</blockquote></td></tr></table><table border="0" cellspacing="0" cellpadding="2"><tr><td bgcolor="#525D76"><font color="#ffffff" face="arial,helvetica.sanserif"><a name="BUILD.XML Configuration File"><strong>BUILD.XML Configuration File</strong></a></font></td></tr><tr><td><blockquote>
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<p>We will be using the <strong>ant</strong> tool to manage the compilation of
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our Java source code files, and creation of the deployment hierarchy. Ant
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operates under the control of a build file, normally called
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<code>build.xml</code>, that defines the processing steps required. This
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file is stored in the top-level directory of your source code hierarchy, and
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should be checked in to your source code control system.</p>
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<p>Like a Makefile, the <code>build.xml</code> file provides several
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"targets" that support optional development activities (such as creating
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the associated Javadoc documentation, erasing the deployment home directory
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so you can build your project from scratch, or creating the web application
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archive file so you can distribute your application. A well-constructed
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<code>build.xml</code> file will contain internal documentation describing
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the targets that are designed for use by the developer, versus those targets
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used internally. To ask Ant to display the project documentation, change to
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the directory containing the <code>build.xml</code> flie and type:</p>
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<div align="left"><table cellspacing="4" cellpadding="0" border="0"><tr><td bgcolor="#023264" width="1" height="1"><img src="../../images/void.gif" width="1" height="1" vspace="0" hspace="0" border="0"></td><td bgcolor="#023264" height="1"><img src="../../images/void.gif" width="1" height="1" vspace="0" hspace="0" border="0"></td><td bgcolor="#023264" width="1" height="1"><img src="../../images/void.gif" width="1" height="1" vspace="0" hspace="0" border="0"></td></tr><tr><td bgcolor="#023264" width="1"><img src="../../images/void.gif" width="1" height="1" vspace="0" hspace="0" border="0"></td><td bgcolor="#ffffff" height="1"><pre>
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ant -projecthelp
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</pre></td><td bgcolor="#023264" width="1"><img src="../../images/void.gif" width="1" height="1" vspace="0" hspace="0" border="0"></td></tr><tr><td bgcolor="#023264" width="1" height="1"><img src="../../images/void.gif" width="1" height="1" vspace="0" hspace="0" border="0"></td><td bgcolor="#023264" height="1"><img src="../../images/void.gif" width="1" height="1" vspace="0" hspace="0" border="0"></td><td bgcolor="#023264" width="1" height="1"><img src="../../images/void.gif" width="1" height="1" vspace="0" hspace="0" border="0"></td></tr></table></div>
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<p>To give you a head start, a <a href="build.xml.txt">basic build.xml file</a>
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is provided that you can customize and install in the project source directory
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for your application. This file includes comments that describe the various
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targets that can be executed. Briefly, the following targets are generally
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provided:</p>
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<ul>
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<li><strong>clean</strong> - This target deletes any existing
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<code>build</code> and <code>dist</code> directories, so that they
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can be reconstructed from scratch. This allows you to guarantee that
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you have not made source code modifications that will result in
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problems at runtime due to not recompiling all affected classes.
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<br><br></li>
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<li><strong>compile</strong> - This target is used to compile any source code
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that has been changed since the last time compilation took place. The
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resulting class files are created in the <code>WEB-INF/classes</code>
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subdirectory of your <code>build</code> directory, exactly where the
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structure of a web application requires them to be. Because
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this command is executed so often during development, it is normally
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made the "default" target so that a simple <code>ant</code> command will
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execute it.
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<br><br></li>
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<li><strong>all</strong> - This target is a short cut for running the
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<code>clean</code> target, followed by the <code>compile</code> target.
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Thus, it guarantees that you will recompile the entire application, to
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ensure that you have not unknowingly introduced any incompatible changes.
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<br><br></li>
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<li><strong>javadoc</strong> - This target creates Javadoc API documentation
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for the Java classes in this web application. The example
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<code>build.xml</code> file assumes you want to include the API
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documentation with your app distribution, so it generates the docs
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in a subdirectory of the <code>dist</code> directory. Because you normally
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do not need to generate the Javadocs on every compilation, this target is
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usually a dependency of the <code>dist</code> target, but not of the
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<code>compile</code> target.
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<br><br></li>
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<li><strong>dist</strong> - This target creates a distribution directory for
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your application, including any required documentation, the Javadocs for
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your Java classes, and a web application archive (WAR) file that will be
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delivered to system administrators who wish to install your application.
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Because this target also depends on the <code>deploy</code> target, the
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web application archive will have also picked up any external dependencies
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that were included at deployment time.</li>
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</ul>
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<p>For interactive development and testing of your web application using
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Tomcat 5, the following additional targets are defined:</p>
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<ul>
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<li><strong>install</strong> - Tell the currently running Tomcat 5 to make
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the application you are developing immediately available for execution
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and testing. This action does not require Tomcat 5 to be restarted, but
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it is also not remembered after Tomcat is restarted the next time.
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<br><br></li>
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<li><strong>reload</strong> - Once the application is installed, you can
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continue to make changes and recompile using the <code>compile</code>
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target. Tomcat 5 will automatically recognize changes made to JSP pages,
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but not to servlet or JavaBean classes - this command will tell Tomcat
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to restart the currently installed application so that such changes are
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recognized.
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<br><br></li>
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<li><strong>remove</strong> - When you have completed your development and
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testing activities, you can optionally tell Tomcat 5 to remove this
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application from service.
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</li>
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</ul>
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<p>Using the development and testing targets requires some additional
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one-time setup that is described on the next page.</p>
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</blockquote></td></tr></table></td></tr><!--FOOTER SEPARATOR--><tr><td colspan="2"><hr noshade="noshade" size="1"></td></tr><!--PAGE FOOTER--><tr><td colspan="2"><div align="center"><font color="#525D76" size="-1"><em>
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Copyright © 1999-2006, Apache Software Foundation
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</em></font></div></td></tr></table></body></html> |