The Apache Project

6.2 Installation

Prerequisite Software

The Struts binary distribution needs three other software packages installed to operate. You may already have these installed on your system. To build Struts from source you may need to acquire and install several others. The complete list is as follows:

  • Java Development Kit - You must download and install a Java2 (version 1.2 or later) Java Development Kit implementation for your operating system platform. A good starting point for locating Java Development Kit distributions is http://java.sun.com/j2se. To build Struts, Java 1.4.2 (the latest production JDK) is suggested.
  • Servlet Container - You must download and install a servlet container that is compatible with the Servlet API Specification, version 2.2 or later, and the JavaServer Pages (JSP) Specification, version 1.1 or later. One popular choice is to download Apache's Tomcat, but any compliant container should work well with Struts.
  • XML Parser - Struts requires the presence of an XML parser that is compatible with the Java API for XML Parsing (JAXP) specification, 1.1 or later. This is bundled with J2SE 1.4 and later. For earlier versions of Java, the easiest way to obtain JAXP is probably by downloading the Web Services Developers Kit (1.1 or later!). See the Sun JAXP FAQ for more information.) In Struts-based web applications, you may replace the reference implementation classes with any other JAXP compliant parser, such as Xerces. See detailed instructions related to the parser in the instructions for building and installing Struts, below.
  • Ant Build System - If you are building Struts from the source distribution, you must download and install version 1.5.4 (or later) of the Ant build system.
    • Make sure that the "ant" and "ant.bat" scripts are executable, by adding the $ANT_HOME/bin directory to your PATH environment variable.
    • Copy and review either the "build.properties.sample" or "build.properties.sample.lib" file as "build.properties". The latter is recommended if you are not active in Jakarta Commons development.
    • Maven property files are also provided, but the Maven build is still experimental. New developers may find Maven easier to use, since it acquires the appropriate JARs automatically.
  • Servlet API Classes - In order to compile Struts itself, or applications that use Struts, you will need a servlet.jar file containing the Servlet and JSP API classes. Most servlet containers include this JAR file. Otherwise, you can get the Servlet API classes distribution from here.
  • JDBC 2.0 Optional Package Classes - Struts supports an optional implementation of javax.sql.DataSource, so it requires the API classes to be compiled. They can be downloaded from http://java.sun.com/products/jdbc/download.html.
  • Other Packages - Struts utilizes several packages from other open source projects, especially the Jakarta Commons Project. These are the packages which must be available if you wish to build Struts from source: ANTLR is a public domain library; all other libraries are distributed under the Apache Software License. For your convenience, the requisite JARs are provided as a single download under the lib sub-directory with each release distribution. Please note that the minimum requirements may change between releases, and some JARs may need to be updated to use the latest Nightly Build.
  • Xalan XSLT Processor - If you are building Struts from the source distribution, you will need a version of Xalan to perform XSLT transformations. If you are using the JAXP/1.1 XML parser, you should use the version of xalan.jar shipped with it. Otherwise, download and install version 1.2 of Xalan from here.
  • Unit tests - To verify your build against the JUnit and Cactus unit tests, three other packages must be available:

Install A Struts Binary Distribution

First, download a binary distribution of Struts by following the instructions here. Then, make sure you have downloaded and installed the prerequisite software packages described above.

Unpack the Struts binary distribution into a convenient directory. (If you build Struts from the source distribution, the result of the build will already be an unpacked binary distribution for you). The distribution consists of the following contents:

  • lib/*.jar - The struts.jar contains the Java classes distributed by the Struts project. The other JAR files contain packages from other projects that are imported by Struts. When you launch a Struts-based application, these JARs need to be available to your application, usually by copying them to the application's WEB-INF/lib directory.
    WARNING - If you are going to be hosting multiple Struts based applications on the same servlet container, you will be tempted to place the struts.jar file into the shared repository supported by your container. Be advised that this may cause ClassNotFoundException problems unless all of your application classes are stored in the shared repository.
  • lib/*.tld - These are the "tag library descriptor" files that describe the custom tags in the various Struts tag libraries. The tld file for any Struts taglibs that you use should be copied into the WEB-INF directory of your web application. (Applications under Servlet 2.3 containers can omit this step if the standard uri is referenced.)
  • webapps/struts-blank.war - This is a simple "web application archive" file containing a basic starting point for building your own Struts-based applications.
  • webapps/struts-documentation.war - This is a "web application archive" file containing all of the Struts documentation found on the Struts web site (including these pages). You can install this web application on any servlet container compatible with Servlet API 2.2 or later.
  • webapps/struts-examples.war - This "modular" applications combines several usefule demonstrations:
    • Exercise-Taglib - This application module contains test pages for the various custom tags distributed with Struts. It is primarily of use to developers who are enhancing the Struts custom tag libraries, but may also be useful as simple examples of the usage of various Struts tags.
    • Upload - This application module is a quick example of uploading files using the Struts framework.
    • Validator - This application module is an example of using the validator framework, using both the server-side and optional client-side validation.
  • webapps/struts-mailreader.war - This is an example web application that uses a large percentage of Struts features. You can install this web application on any servlet container compatible with the Servlet 2.2 (or later) and JSP 1.1 (or later) specifications. If an XML parser is not made available to web applications by your container, you will need to add one to the WEB-INF/lib directory of this web application.
  • webapps/tiles-documentation.war - This web application documents how to use tiles, and was developed using tiles.

To use Struts in your own application, you will need to follow these steps:

  • Copy the lib/*.jar files from the Struts distribution into the WEB-INF/lib directory of your web application.
  • Copy the lib/*.tld files for any Struts taglibs you use from the Struts distribution into the WEB-INF directory of your web application.
  • Modify the WEB-INF/web.xml file for your web application to include a <servlet> element to define the controller servlet, and a <servlet-mapping> element to establish which request URIs are mapped to this servlet. Use the WEB-INF/web.xml file from the Struts example application for a detailed example of the required syntax.
  • Modify the WEB-INF/web.xml file of your web application to include the following tag library declarations (Servlet 2.3 can omit this step if the standard uri is referenced):
<taglib>
  <taglib-uri>/WEB-INF/struts-bean.tld</taglib-uri>
  <taglib-location>/WEB-INF/struts-bean.tld</taglib-location>
</taglib>

<taglib>
  <taglib-uri>/WEB-INF/struts-html.tld</taglib-uri>
  <taglib-location>/WEB-INF/struts-html.tld</taglib-location>
</taglib>

<taglib>
  <taglib-uri>/WEB-INF/struts-logic.tld</taglib-uri>
  <taglib-location>/WEB-INF/struts-logic.tld</taglib-location>
</taglib>
  • Create a file WEB-INF/struts-config.xml that defines the action mappings and other characteristics of your specific application. You can use the struts-config.xml file from the Struts example application for a detailed example of the required syntax.
  • At the top of each JSP page that will use the Struts custom tags, add line(s) declaring the Struts custom tag libraries used on this particular page, like this:
<%@ taglib uri="/tags/struts-bean" prefix="bean" %>
<%@ taglib uri="/tags/struts-html" prefix="html" %>
<%@ taglib uri="/tags/struts-logic" prefix="logic" %>
  • When compiling the Java classes that comprise your application, be sure to include the JAR files (copied earlier) on the CLASSPATH that is submitted to the compiler.

Installing Struts With Your Servlet Container

For most containers, you need only to:

  • Copy the WAR files in your Struts /webapp directory to your containers webapps directory.
  • In some cases, you may need to restart your container if it is running.

Running Struts Applications Under A Security Manager

Many application servers execute web applications under the control of a Java security manager, with restricted permissions on what classes in the web application can do. If you utilize form beans with mapped properties, you may encounter security exceptions unless you add the following permission to the set of permissions granted to your Struts application's codebase:

  permission java.lang.RuntimePermission "accessDeclaredMembers";

Consult the documentation on your application server for more information about how to configure additional security manager permissions.

Installing Struts on Various Containers

Building Struts From Source

First, download a source distribution of Struts by following the instructions here. Then, make sure you have downloaded and installed all of the prerequisite software packages described above.

To build Struts, you will need to customize the build process to the details of your development environment as follows:

  • The Struts source distribution uses a file named build.properties (in the top-level directory of the distribution) to identify the location of external components that Struts depends on.
  • There is no build.properties file included with the source distribution. However, there is an example file named build.properties.example that you can copy to build.properties and then customize.
  • The properties you must configure in build.properties are:
    • catalina.home - Pathname to the directory of your binary distribution of Tomcat 4.0 (required only if you wish to use the deploy.catalina target).
    • commons-beanutils.jar - Pathname of the BeanUtils package JAR file from the Jakarta Commons project.
    • commons-collections.jar - Pathname of the Collections package JAR file from the Jakarta Commons project.
    • commons-digester.jar - Pathname of the Digester package JAR file from the Jakarta Commons project.
    • commons-fileupload.jar - Pathname of the Fileupload package JAR file from the Jakarta Commons project.
    • commons-lang.jar - Pathname of the Lang package JAR file from the Jakarta Commons project.
    • commons-logging.jar - Pathname of the Logging package JAR file from the Jakarta Commons project.
    • commons-validator.jar - Pathname of the Validator package JAR file from the Jakarta Commons project.
    • servletapi.home - Pathname to the directory of your binary distribution of the Servlet API classes.
    • tomcat.home - Pathname to the directory of your binary distribution of Tomcat 3.2 (required only if you wish to use the deploy.tomcat target).
    • xerces.home - Pathname to the directory of your binary distribution of the Xerces parser, version 1.2 or 1.3 (required only if you wish to use the deploy.catalina target).
  • If you are a Struts developer with write access to the CVS repository, be sure that you do NOT check in a copy of the build.properties file, since it will be different for each individual developer.

To build a "distribution" version of Struts, first change your current directory to the directory in which you have unpacked the Struts source distribution, and (if necessary) create or customize the build.properties file as described above. Then, type:

        ant dist

This command will create a binary distribution of Struts, in a directory named dist (relative to where you are compiling from). This directory contains an exact replica of the files included in a binary distribution of Struts, as described in the preceding section.

IMPORTANT NOTE: The struts.jar, as well as the JAR files from the Jakarta Commons project, must be in your classpath when compiling Struts. The build.xml provided does this automatically. If you use your development machine to test Struts application locally, be sure that the struts.jar is NOT on your classpath when your container is running.

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