I have seen so many people using Ant to build a war file. But lots of people are not aware of the attributes they have used and why they have used?. It is not the right way and if you want to change anything you have to wait for somebody to help you.

I have given a sample build.xml file and description. If you take a look you can get better idea about ant file.

Apache Ant (or simply Ant) is an XML-based build scripting language used heavily by the Open Source community. Ant automates tasks such as compiling source code, building deployment packages and automatically checking dependencies of what items need to be updated in a build set.

Here are a few things to note:

1. The Begin and End tags for project ( and ) MUST start and end the file.
2. The Begin MUST have an attribute called default which is the name of one of the targets
3. Each build file must have at least one target
4. The Begin and End tags for and must also match EXACTLY.
5. Each target MUST have a name
6. Targets depend only on other targets and reference them by their target name. Targets NEVER depend on projects or tasks
7. Target depends are optional
8. Anything between and tags is outputted to the console if the surrounding target is called

Ant does not have variables like in most standard programming languages. Ant has a structure called properties.

General purpose build script for web applications and web services, including enhanced support for deploying directly to a Tomcat 4 based server.

This build script assumes that the source code of your web application is organized into the following sub directories underneath the source code directory from which you execute the build script:

docs Static documentation files to be copied to the “docs” sub directory of your distribution.

src Java source code (and associated resource files) to be compiled to the “WEB-INF/classes”
subdirectory of your web application. web Static HTML, JSP, and other content (such as
image files), including the WEB-INF subdirectory
and its configuration file contents.

A “project” describes a set of targets that may be requested when Ant is executed. The “default” attribute defines the target which is executed if no specific target is requested, and the “basedir” attribute defines the current working directory from which Ant executes the requested task. This is normally set to the current working directory.

<project name=”My Project” default=”compile” basedir=”.”>

Each of the following properties are used in the build script.
Values for these properties are set by the first place they are
defined, from the following list:

* Definitions on the “Ant” command line (ant -Dfoo=bar compile).

* Definitions from a “build.properties” file in the top level
source directory of this application.

* Definitions from a “build.properties” file in the developer’s
home directory.

* Default definitions in this build.xml file.

You will note below that property values can be composed based on the
contents of previously defined properties. This is a powerful technique
that helps you minimize the number of changes required when your development
environment is modified. Note that property composition is allowed within
“build.properties” files as well as in the “build.xml” script.

These properties generally define file and directory names (or paths) that affect where the build process stores its outputs.

app.name Base name of this application, used to construct filenames and directories.
Defaults to “myapp”.

app.path Context path to which this application should be deployed (defaults to “/” plus the value of the “app.name” property).

app.version Version number of this iteration of the application. build.home The directory into which the “prepare” and “compile” targets will generate their output.
Defaults to “build”. catalina.home The directory in which you have installed
a binary distribution of Tomcat 4. This will be used by the “deploy” target.

dist.home The name of the base directory in which distribution files are created.
Defaults to “dist”.manager.password The login password of a user that is assigned the
“manager” role (so that he or she can execute commands via the “/manager” web application)

manager.url The URL of the “/manager” web application on the Tomcat installation to which we will deploy web applications and web services.

manager.username The login username of a user that is assigned the “manager” role (so that he or she can execute commands via the “/manager” web application)

These properties define custom tasks for the Ant build tool that interact with the “/manager” web application installed with Tomcat 4. Before they can be successfully utilized, you must perform the following steps:

Copy the file “server/lib/catalina-ant.jar” from your Tomcat 4 installation into the “lib” directory of your Ant installation.

Create a “build.properties” file in your application’s top-level source directory (or your user login home directory) that defines appropriate values for the “manager.password”, “manager.url”, and “manager.username” properties described above.

For more information about the Manager web application, and the functionality
of these tasks, see <http://localhost:8080/tomcat-docs/manager-howto.html>.

These properties control option settings on the Javac compiler when it is invoked using the <javac> task. compile.debug Should compilation include the debug option? compile.deprecation Should compilation include the deprecation option?

compile.optimize Should compilation include the optimize option?

Use property values to define the locations of external JAR files on which your application will depend. In general, these values will be used for two purposes: * Inclusion on the classpath that is passed to the Javac compiler * Being copied into the “/WEB-INF/lib” directory during execution of the “deploy” target.

Because we will automatically include all of the Java classes that Tomcat 4 exposes to web applications, we will not need to explicitly list any of those dependencies. You only need to worry about external dependencies for JAR files that you are going to include inside your “/WEB-INF/lib” directory.

Rather than relying on the CLASSPATH environment variable, Ant includes
features that makes it easy to dynamically construct the classpath you
need for each compilation. The example below constructs the compile
classpath to include the servlet.jar file, as well as the other components
that Tomcat makes available to web applications automatically, plus anything
that you explicitly added.

The “all” target is a shortcut for running the “clean” target followed
by the “compile” target, to force a complete recompile.

<target name=”all” depends=”clean,compile”
description=”Clean build and dist directories, then compile”/>

The “clean” target deletes any previous “build” and “dist” directory, so that you can be ensured the application can be built from scratch.

The “compile” target transforms source files (from your “src” directory) into object files in the appropriate location in the build directory. This example assumes that you will be including your classes in an unpacked directory hierarchy under “/WEB-INF/classes”.

The “dist” target creates a binary distribution of your application in a directory structure ready to be archived in a tar.gz or zip file. Note that this target depends on two others:

* “compile” so that the entire web application (including external
dependencies) will have been assembled

* “javadoc” so that the application Javadocs will have been created

The “install” target tells the specified Tomcat 4 installation to dynamicallyinstall this web application and make it available for execution. It does *not* cause the existence of this web application to be remembered across Tomcat restarts; if you restart the server, you will need to re-install all this web application.

If you have already installed this application, and simply want Tomcat to recognize that you have updated Java classes (or the web.xml file), use the “reload” target instead.

NOTE: This target will only succeed if it is run from the same server that Tomcat is running on.

NOTE: This is the logical opposite of the “remove” target.

The “javadoc” target creates Javadoc API documentation for the Java classes included in your application. Normally, this is only required when preparing a distribution release, but is available as a separate target in case the developer wants to create Javadocs independently.

The “list” target asks the specified Tomcat 4 installation to list the currently running web applications, either loaded at start up time or installed dynamically. It is useful to determine whether or not the application you are currently developing has been installed.

The “prepare” target is used to create the “build” destination directory, and copy the static contents of your web application to it. If you need to copy static files from external dependencies, you can customize the contents of this task. Normally, this task is executed indirectly when needed.

The “reload” signals the specified application Tomcat 4 to shut itself down and reload. This can be useful when the web application context is not reloadable and you have updated classes or property files in the /WEB-INF/classes directory or when you have added or updated jar files in the /WEB-INF/lib directory.

NOTE: The /WEB-INF/web.xml web application configuration file is not reread
on a reload. If you have made changes to your web.xml file you must stop
then start the web application.

The “remove” target tells the specified Tomcat 4 installation to dynamically remove this web application from service.

NOTE: This is the logical opposite of the “install” target.

I will be happy to receive your comments.
contact me for any help at imamoo(at)ipott(dot)com

Courtesy Tomcat Apache org