| <html><head><META http-equiv="Content-Type" content="text/html; charset=iso-8859-1"><title>Application Developer's Guide (6.0.39) - Deployment</title><meta name="author" content="Craig R. McClanahan"><style type="text/css" media="print"> | |
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| </style></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=" | |
| The Apache Tomcat Servlet/JSP Container | |
| " border="0"></a></td><td><h1><font face="arial,helvetica,sanserif">Apache Tomcat 6.0</font></h1><font face="arial,helvetica,sanserif">Version 6.0.39, Jan 27 2014</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><!--LEFT SIDE NAVIGATION--><td width="20%" valign="top" nowrap="nowrap" class="noPrint"><p><strong>Links</strong></p><ul><li><a href="../index.html">Docs Home</a></li></ul><p><strong>Contents</strong></p><ul><li><a href="index.html">Contents</a></li><li><a href="introduction.html">Introduction</a></li><li><a href="installation.html">Installation</a></li><li><a href="deployment.html">Deployment</a></li><li><a href="source.html">Source Code</a></li><li><a href="processes.html">Processes</a></li><li><a href="sample/">Example App</a></li></ul></td><!--RIGHT SIDE MAIN BODY--><td width="80%" valign="top" align="left" id="mainBody"><h1>Application Developer's Guide</h1><h2>Deployment</h2><table border="0" cellspacing="0" cellpadding="2"><tr><td bgcolor="#525D76"><font color="#ffffff" face="arial,helvetica.sanserif"><a name="Table of Contents"><!--()--></a><a name="Table_of_Contents"><strong>Table of Contents</strong></a></font></td></tr><tr><td><blockquote> | |
| <ul><li><a href="#Background">Background</a></li><li><a href="#Standard_Directory_Layout">Standard Directory Layout</a></li><li><a href="#Shared_Library_Files">Shared Library Files</a></li><li><a href="#Web_Application_Deployment_Descriptor">Web Application Deployment Descriptor</a></li><li><a href="#Tomcat_Context_Descriptor">Tomcat Context Descriptor</a></li><li><a href="#Deployment_With_Tomcat_6">Deployment With Tomcat 6</a></li></ul> | |
| </blockquote></td></tr></table><table border="0" cellspacing="0" cellpadding="2"><tr><td bgcolor="#525D76"><font color="#ffffff" face="arial,helvetica.sanserif"><a name="Background"><strong>Background</strong></a></font></td></tr><tr><td><blockquote> | |
| <p>Before describing how to organize your source code directories, | |
| it is useful to examine the runtime organization of a web application. | |
| Prior to the Servlet API Specification, version 2.2, there was little | |
| consistency between server platforms. However, servers that conform | |
| to the 2.2 (or later) specification are required to accept a | |
| <em>Web Application Archive</em> in a standard format, which is discussed | |
| further below.</p> | |
| <p>A web application is defined as a hierarchy of directories and files | |
| in a standard layout. Such a hierarchy can be accessed in its "unpacked" | |
| form, where each directory and file exists in the filesystem separately, | |
| or in a "packed" form known as a Web ARchive, or WAR file. The former format | |
| is more useful during development, while the latter is used when you | |
| distribute your application to be installed.</p> | |
| <p>The top-level directory of your web application hierarchy is also the | |
| <em>document root</em> of your application. Here, you will place the HTML | |
| files and JSP pages that comprise your application's user interface. When the | |
| system administrator deploys your application into a particular server, he | |
| or she assigns a <em>context path</em> to your application (a later section | |
| of this manual describes deployment on Tomcat). Thus, if the | |
| system administrator assigns your application to the context path | |
| <code>/catalog</code>, then a request URI referring to | |
| <code>/catalog/index.html</code> will retrieve the <code>index.html</code> | |
| file from your document root.</p> | |
| </blockquote></td></tr></table><table border="0" cellspacing="0" cellpadding="2"><tr><td bgcolor="#525D76"><font color="#ffffff" face="arial,helvetica.sanserif"><a name="Standard Directory Layout"><!--()--></a><a name="Standard_Directory_Layout"><strong>Standard Directory Layout</strong></a></font></td></tr><tr><td><blockquote> | |
| <p>To facilitate creation of a Web Application Archive file in the required | |
| format, it is convenient to arrange the "executable" files of your web | |
| application (that is, the files that Tomcat actually uses when executing | |
| your app) in the same organization as required by the WAR format itself. | |
| To do this, you will end up with the following contents in your | |
| application's "document root" directory:</p> | |
| <ul> | |
| <li><strong>*.html, *.jsp, etc.</strong> - The HTML and JSP pages, along | |
| with other files that must be visible to the client browser (such as | |
| JavaScript, stylesheet files, and images) for your application. | |
| In larger applications you may choose to divide these files into | |
| a subdirectory hierarchy, but for smaller apps, it is generally | |
| much simpler to maintain only a single directory for these files. | |
| <br><br></li> | |
| <li><strong>/WEB-INF/web.xml</strong> - The <em>Web Application Deployment | |
| Descriptor</em> for your application. This is an XML file describing | |
| the servlets and other components that make up your application, | |
| along with any initialization parameters and container-managed | |
| security constraints that you want the server to enforce for you. | |
| This file is discussed in more detail in the following subsection. | |
| <br><br></li> | |
| <li><strong>/WEB-INF/classes/</strong> - This directory contains any Java | |
| class files (and associated resources) required for your application, | |
| including both servlet and non-servlet classes, that are not combined | |
| into JAR files. If your classes are organized into Java packages, | |
| you must reflect this in the directory hierarchy under | |
| <code>/WEB-INF/classes/</code>. For example, a Java class named | |
| <code>com.mycompany.mypackage.MyServlet</code> | |
| would need to be stored in a file named | |
| <code>/WEB-INF/classes/com/mycompany/mypackage/MyServlet.class</code>. | |
| <br><br></li> | |
| <li><strong>/WEB-INF/lib/</strong> - This directory contains JAR files that | |
| contain Java class files (and associated resources) required for your | |
| application, such as third party class libraries or JDBC drivers.</li> | |
| </ul> | |
| <p>When you install an application into Tomcat (or any other | |
| 2.2/2.3-compatible server), the classes in the <code>WEB-INF/classes/</code> | |
| directory, as well as all classes in JAR files found in the | |
| <code>WEB-INF/lib/</code> directory, are made visible to other classes | |
| within your particular web application. Thus, if | |
| you include all of the required library classes in one of these places (be | |
| sure to check licenses for redistribution rights for any third party libraries | |
| you utilize), you will simplify the installation of your web application -- | |
| no adjustment to the system class path (or installation of global library | |
| files in your server) will be necessary.</p> | |
| <p>Much of this information was extracted from Chapter 9 of the Servlet | |
| API Specification, version 2.3, which you should consult for more details.</p> | |
| </blockquote></td></tr></table><table border="0" cellspacing="0" cellpadding="2"><tr><td bgcolor="#525D76"><font color="#ffffff" face="arial,helvetica.sanserif"><a name="Shared Library Files"><!--()--></a><a name="Shared_Library_Files"><strong>Shared Library Files</strong></a></font></td></tr><tr><td><blockquote> | |
| <p>Like most servlet containers, Tomcat 6 also supports mechanisms to install | |
| library JAR files (or unpacked classes) once, and make them visible to all | |
| installed web applications (without having to be included inside the web | |
| application itself). The details of how Tomcat locates and shares such | |
| classes are described in the | |
| <a href="../class-loader-howto.html">Class Loader HOW-TO</a> documentation. | |
| The location commonly used within a Tomcat 6 installation for shared code is | |
| <strong>$CATALINA_HOME/lib</strong>. JAR files placed here are visible both to | |
| web applications and internal Tomcat code. This is a good place to put JDBC | |
| drivers that are required for both your application or internal Tomcat use | |
| (such as for a JDBCRealm).</p> | |
| <p>Out of the box, a standard Tomcat 6 installation includes a variety | |
| of pre-installed shared library files, including:</p> | |
| <ul> | |
| <li>The <em>Servlet 2.5</em> and <em>JSP 2.1</em> APIs that are fundamental | |
| to writing servlets and JavaServer Pages.<br><br></li> | |
| </ul> | |
| </blockquote></td></tr></table><table border="0" cellspacing="0" cellpadding="2"><tr><td bgcolor="#525D76"><font color="#ffffff" face="arial,helvetica.sanserif"><a name="Web Application Deployment Descriptor"><!--()--></a><a name="Web_Application_Deployment_Descriptor"><strong>Web Application Deployment Descriptor</strong></a></font></td></tr><tr><td><blockquote> | |
| <p>As mentioned above, the <code>/WEB-INF/web.xml</code> file contains the | |
| Web Application Deployment Descriptor for your application. As the filename | |
| extension implies, this file is an XML document, and defines everything about | |
| your application that a server needs to know (except the <em>context path</em>, | |
| which is assigned by the system administrator when the application is | |
| deployed).</p> | |
| <p>The complete syntax and semantics for the deployment descriptor is defined | |
| in Chapter 13 of the Servlet API Specification, version 2.3. Over time, it | |
| is expected that development tools will be provided that create and edit the | |
| deployment descriptor for you. In the meantime, to provide a starting point, | |
| a <a href="web.xml.txt">basic web.xml file</a> | |
| is provided. This file includes comments that describe the purpose of each | |
| included element.</p> | |
| <p><strong>NOTE</strong> - The Servlet Specification includes a Document | |
| Type Descriptor (DTD) for the web application deployment descriptor, and | |
| Tomcat 6 enforces the rules defined here when processing your application's | |
| <code>/WEB-INF/web.xml</code> file. In particular, you <strong>must</strong> | |
| enter your descriptor elements (such as <code><filter></code>, | |
| <code><servlet></code>, and <code><servlet-mapping></code> in | |
| the order defined by the DTD (see Section 13.3).</p> | |
| </blockquote></td></tr></table><table border="0" cellspacing="0" cellpadding="2"><tr><td bgcolor="#525D76"><font color="#ffffff" face="arial,helvetica.sanserif"><a name="Tomcat Context Descriptor"><!--()--></a><a name="Tomcat_Context_Descriptor"><strong>Tomcat Context Descriptor</strong></a></font></td></tr><tr><td><blockquote> | |
| <p>A /META-INF/context.xml file can be used to define Tomcat specific | |
| configuration options, such as an access log, data sources, session manager | |
| configuration and more. This XML file must contain one Context element, which | |
| will be considered as if it was the child of the Host element corresponding | |
| to the Host to which the web application is being deployed. The | |
| <a href="../config/index.html">Tomcat configuration documentation</a> contains | |
| information on the Context element.</p> | |
| </blockquote></td></tr></table><table border="0" cellspacing="0" cellpadding="2"><tr><td bgcolor="#525D76"><font color="#ffffff" face="arial,helvetica.sanserif"><a name="Deployment With Tomcat 6"><!--()--></a><a name="Deployment_With_Tomcat_6"><strong>Deployment With Tomcat 6</strong></a></font></td></tr><tr><td><blockquote> | |
| <blockquote><em> | |
| <p>The description below uses the variable name $CATALINA_BASE to refer the | |
| base directory against which most relative paths are resolved. If you have | |
| not configured Tomcat 6 for multiple instances by setting a CATALINA_BASE | |
| directory, then $CATALINA_BASE will be set to the value of $CATALINA_HOME, | |
| the directory into which you have installed Tomcat 6.</p> | |
| </em></blockquote> | |
| <p>In order to be executed, a web application must be deployed on | |
| a servlet container. This is true even during development. | |
| We will describe using Tomcat 6 to provide the execution environment. | |
| A web application can be deployed in Tomcat by one of the following | |
| approaches:</p> | |
| <ul> | |
| <li><em>Copy unpacked directory hierarchy into a subdirectory in directory | |
| <code>$CATALINA_BASE/webapps/</code></em>. Tomcat will assign a | |
| context path to your application based on the subdirectory name you | |
| choose. We will use this technique in the <code>build.xml</code> | |
| file that we construct, because it is the quickest and easiest approach | |
| during development. Be sure to restart Tomcat after installing or | |
| updating your application. | |
| <br><br></li> | |
| <li><em>Copy the web application archive file into directory | |
| <code>$CATALINA_BASE/webapps/</code></em>. When Tomcat is started, it will | |
| automatically expand the web application archive file into its unpacked | |
| form, and execute the application that way. This approach would typically | |
| be used to install an additional application, provided by a third party | |
| vendor or by your internal development staff, into an existing | |
| Tomcat installation. <strong>NOTE</strong> - If you use this approach, | |
| and wish to update your application later, you must both replace the | |
| web application archive file <strong>AND</strong> delete the expanded | |
| directory that Tomcat created, and then restart Tomcat, in order to reflect | |
| your changes. | |
| <br><br></li> | |
| <li><em>Use the Tomcat 6 "Manager" web application to deploy and undeploy | |
| web applications</em>. Tomcat 6 includes a web application, deployed | |
| by default on context path <code>/manager</code>, that allows you to | |
| deploy and undeploy applications on a running Tomcat server without | |
| restarting it. See the administrator documentation (TODO: hyperlink) | |
| for more information on using the Manager web application.<br><br></li> | |
| <li><em>Use "Manager" Ant Tasks In Your Build Script</em>. Tomcat 6 | |
| includes a set of custom task definitions for the <code>Ant</code> | |
| build tool that allow you to automate the execution of commands to the | |
| "Manager" web application. These tasks are used in the Tomcat deployer. | |
| <br><br></li> | |
| <li><em>Use the Tomcat Deployer</em>. Tomcat 6 includes a packaged tool | |
| bundling the Ant tasks, and can be used to automatically precompile JSPs | |
| which are part of the web application before deployment to the server. | |
| <br><br></li> | |
| </ul> | |
| <p>Deploying your app on other servlet containers will be specific to each | |
| container, but all containers compatible with the Servlet API Specification | |
| (version 2.2 or later) are required to accept a web application archive file. | |
| Note that other containers are <strong>NOT</strong> required to accept an | |
| unpacked directory structure (as Tomcat does), or to provide mechanisms for | |
| shared library files, but these features are commonly available.</p> | |
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