@@ -1,6 +1,6 @@
<head>
<title>
Apache Ant in Anger
Ant in Anger
</title>
</head>
@@ -8,11 +8,12 @@
<h1 align="center">Ant in Anger:
</h1>
<h2 align="center">
Using Apache Ant in a Production Development System
Using Apache Ant in a Production Development System
</h2>
<h4 align="center">
Steve Loughran
Steve Loughran<br>
Last updated 2002-11-09
</h4>
<a name="introduction">
@@ -25,8 +26,8 @@ Steve Loughran
be yet another source of problems in that ongoing crises we call
development . This
document contains some strategies and tactics for making the most of
a nt. It is moderately frivolous in places, and lacks almost any actual
examples of a nt xml. The lack of examples is entirely deliberate -it
A nt. It is moderately frivolous in places, and lacks almost any actual
examples of A nt xml. The lack of examples is entirely deliberate -it
keeps document maintenance costs down. Most of the concepts covered
don't need the detail about XML representations, as it is processes we
are concerned about, not syntax. Finally, please be aware that the
@@ -36,7 +37,7 @@ done.
<p>
Firstly, here are some assumptions about the projects which this
document covers
document covers:
<ul>
<li> Pretty much pure Java, maybe with some legacy cruft on the edges.
@@ -63,7 +64,7 @@ late next century the date coming up from below.
What that all means is that there is no time to spend getting things
right, you don't have that tight control on how the rest of the team
works and the development process is often more one of chaos minimisation
than anything else. The role of a nt in such projects is to ensure that
than anything else. The role of A nt in such projects is to ensure that
the build, test and deploy processes run smoothly, leaving you with all
the other problems.
@@ -71,25 +72,28 @@ the other problems.
<h2>Core Practices</h2>
</a>
<h3>
Clarify what you want a nt to do</h3>
Clarify what you want A nt to do</h3>
Ant is not a silver bullet. It is just another rusty bullet in the armory of
development tools available at your disposal. Its primary purpose is to
accelerate the construction and deployment of Java projects. You could certainly
extend ant to do anything Java makes possible - it is easy to imagine writing an
extend Ant to do anything Java makes possible: it is easy to imagine writing an
image processing task to help in web site deployment by shrinking and
recompressing jpeg files, for example. But that would be pushing the boundary of
what a nt is really intended to do -so should be considered with care.
what A nt is really intended to do -so should be considered with care.
<P>
Ant is also a great adjunct to an IDE - a way of doing all the housekeeping of
Ant is also a great adjunct to an IDE; a way of doing all the housekeeping of
deployment and for clean, automated builds. But a good modern IDE is a
productivity tool in its own right -one you should consider keeping using. Ant
just lets you give the teams somewhat more freedom in IDE choice -"you can
use whatever you want in development, but ant for the deployment
builds"
use whatever you want in development, but Ant for the deployment
builds" Now that many modern open source and commercial IDEs
include Ant support (including jEdit, Forte, Eclipse and IDEA),
developers can use a great IDE, with Ant providing a rigorous and portable
build process integrated into the tool.
<h3>
Define standard targets
@@ -104,9 +108,9 @@ And of course, the ubiquitous <b>clean</b> target.
<P>
With standard target names, it is easy to build encompassing a nt build
With standard target names, it is easy to build encompassing A nt build
files which just hand off the work to the classes below using the
<a href="manual/CoreTasks/ant.html">ant</a>
<a href="manual/CoreTasks/ant.html">< ant> </a>
task. For example. the clean target could be handed down to the <tt>intf</tt> and
<tt>impl</tt> subdirectories from a parent directory
@@ -114,11 +118,11 @@ task. For example. the clean target could be handed down to the <tt>intf</tt> an
</target>
<target name="clean-intf" >
<ant dir="intf" target="clean" />
<ant dir="intf" target="clean" />
</target>
<target name="clean-impl">
<ant dir="impl" target="clean" />
<ant dir="impl" target="clean" />
</target> </pre>
If you give targets a <tt>description</tt> tag, then calling <tt>ant
@@ -127,30 +131,39 @@ all tasks without a description as subtargets. Describing all your
entry points is therefore very useful, even before a project becomes big and complicated.
<h3>
Extend a nt through new tasks
Extend A nt through new tasks
</h3>
If a nt does not do what you want, you can use the
If A nt does not do what you want, you can use the
<a href="manual/CoreTasks/exec.html">exec</a> and
<a href="manual/CoreTasks/java.html">java</a> tasks or
<a href="manual/OptionalTasks/script.html">inline scripting</a> to extend it. In a
project with many build.xml files, you soon find that having a single
central place for implementing the functionality keeps maintenance
overhead down. Implementing task extensions through j ava code seems
overhead down. Implementing task extensions through J ava code seems
extra effort at first, but gives extra benefits:-
<ul>
<ul>
<li>Cross platform support can be added later without changing any
build.xml files</li>
<li>The code can be submitted to the a nt project itself, for other
<li>The code can be submitted to the A nt project itself, for other
people to use and maintain</li>
<li>It keeps the build files simpler</li>
</ul>
In a way, it is it this decoupling of functionality, "the tasks", from
the declaration of use, "the build file", that has helped Ant succeed.
If you have to get something complex done in Make or an IDE, you have a
hairy makefile that everyone is scared of, or an IDE configuration that
is invariably very brittle. But an Ant task is reusable and shareable
among all Ant users. Many of the core and optional tasks in Ant today,
tasks you do or will come to depend on, were written by people trying to
solve their own pressing problems.
<h3>
Embrace Automated Testing
</h3>
@@ -158,23 +171,27 @@ Embrace Automated Testing
<b>(alternatively "recriminate early, recriminate often")</b>
<p>
Ant lets you call <a href="manual/OptionalTasks/junit.html">JUnit</a> tasks, which unit test
the code your team has written. Automated testing may seem like extra
work at first, but JUnit makes writing unit tests so easy that you have
almost no reason not to. Invest the time in learning how to use
JUnit, write the test cases, and integrate them in a 'test' target from
ant so that your daily or hourly team build can have the tests applied
automatically.
Ant lets you call <a href="manual/OptionalTasks/junit.html">JUnit</a>
tasks, which unit test the code your team has written. Automated testing
may seem like extra work at first, but JUnit makes writing unit tests so
easy that you have almost no reason not to. Invest the time in learning
how to use JUnit, write the test cases, and integrate them in a 'test'
target from Ant so that your daily or hourly team build can have the
tests applied automatically. One of the free to download chapters of
<a href="http://manning.com/antbook/">Java Development with Ant</a>
shows you how to use JUnit from inside Ant.
<p>
Once code fetches from the code control system are added as another ant
target, the integration test code can be a pure ant task run on any box
dedicated to the task. This is ideal for verifying that the build and
unit tests work on different targets from the usual development
machines. For example, a Win95/Java1.1 combination could be used even
though no developer would willingly use that configuration given the
choice.
Once you add a way to fetch code from the SCM system, either as an Ant
task, in some shell script or batch file or via some continuous
integration tool. the integration test code can be a pure Ant task run
on any box dedicated to the task. This is ideal for verifying that the
build and unit tests work on different targets from the usual
development machines. For example, a Win95/Java1.1 combination could be
used even though no developer would willingly use that configuration
given the choice.
<p>
@@ -192,6 +209,43 @@ deriving great unit, system and regression tests -but your customers will love
you for shipping software that works.
<h3>Learn to Use and love the add-ons to Ant</h3>
The Ant distribution is not the limit of the Ant universe, it is only
the beginning. Look at the
<A href="http://jakarta.apache.org/ant/external.html">
External Tools and Tasks page
</A> for an up to date list. Here are some of them that .
<ul>
<li>
<a hef="http://checkstyle.sourceforge.net/">Checkstyle</a><br>
This tool audits your code and generates HTML reports of wherever any
style rule gets broken. Nobody can hide from the code police now! tip:
start using this early, so the corrections are less.
<li>
<A href="http://ant-contrib.sf.net/">Ant-contrib</A><br>
This sourceforge project contains helper tasks that are kept separate
from core Ant for ideological purity; the foreach and trycatch tasks in
particular. These give you iteration and extra error handling. Also on
the site is the <cc> task suite, that compile and link native code
on a variety of platforms.
<li>
<a href="http://xdoclet.sourceforge.net/">XDoclet</a>
XDoclet adds attributed oriented programming to Java. By adding javadoc
tags to your code you can have XDoclet automatically generate web.xml
descriptors, taglib descriptors, EJB interfaces, JMX interface classes,
Castor XML/SQL bindings, and many more. The key here is that all those
fiddly little XML files you need to create, and those interfaces EJB and
JMX requires to to implement, all can be autogenerated from your Java
code with a few helper attributes. This reduces
errors and means you can change your code and have the rest of the app
take its cue from the source. Never do EJB, JMX or webapps without it!
</ul>
<a name="crossplatform">
<h2>
Cross Platform Ant
@@ -205,12 +259,12 @@ single workstation.
<p>
The common barriers to cross-platform a nt are the use of command line
The common barriers to cross-platform A nt are the use of command line
tools (exec tasks) which are not portable, path issues, and hard coding
in the location of things.
<h3>Command Line apps: <a href="manual/CoreTasks/exec.html">Exec</a>/ <a href=
"manual/CoreTasks/apply.html">Apply</a></h3>
<h3>Command Line apps: <a href="manual/CoreTasks/exec.html">Exec</a>/
<a href= "manual/CoreTasks/apply.html">Apply</a></h3>
The trouble with external invocation is that not all functions are found
cross platform, and those that are often have different names -DOS
@@ -225,7 +279,7 @@ clashes arising.
Both the command line invocation tasks let you specify which platform
you want the code to run on, so you could write different tasks for each
platform you are targeting. Alternatively, the platform differences
could be handled inside some external code which a nt calls. This can be
could be handled inside some external code which A nt calls. This can be
some compiled down java in a new task, or an external script file.
<h3>Cross platform paths</h3>
@@ -248,7 +302,7 @@ that 'DOS-like pathnames are handled', 'Unix like paths are handled'.
Disk drives -'C:'- are handled on DOS-based boxes, but placing them in
the build.xml file ruins all chances of portability. Relative file paths
are much more portable. Semicolons work as path separators -a fact which
is useful if your a nt invocation wrapper includes a list of jars as a
is useful if your A nt invocation wrapper includes a list of jars as a
defined property in the command line. In the build files you may find it
better to build a classpath by listing individual files (using location=
attributes), or by including a fileset of *.jar in the classpath
@@ -297,7 +351,11 @@ distributions, and is a simple download for <a href=
ActiveState</a>. A Perl file with .pl extension, with the usual Unix
path to perl on the line 1 comment and marked as executable can be run
on Windows, OS/2 and Unix and hence called from Ant without issues. The
perl code can be left to resolve its own platform issues.
perl code can be left to resolve its own platform issues. Dont forget to
set the line endings of the file to the appropriate platform when you
redistribute Perl code; <a
href="manual/CoreTasks/fixcrlf.html"><fixCRLF></a>
can do that for you.
<a name="team">
<h2>Team Development Processes</h2>
@@ -319,7 +377,7 @@ Another good tactic is to use a unified directory tree, and add on extra
tools inside that tree. All references can be made relative to the tree.
If team members are expected to add a directory in the project to their
path, then command line tools can be included there -including those
invoked by a nt exec tasks. Put everything under source code control and
invoked by A nt exec tasks. Put everything under source code control and
you have a one stop shop for getting a build/execute environment purely
from CVS or your equivalent.
@@ -328,21 +386,22 @@ from CVS or your equivalent.
<h2>Deploying with Ant</h2>
</a>
One big difference between ant and older tools such as m ake is that the
processes for deploying j ava to remote sites are reasonably well
evolved in an t. That is because we all have to do it these days, so
One big difference between Ant and older tools such as M ake is that the
processes for deploying J ava to remote sites are reasonably well
evolved in aA t. That is because we all have to do it these days, so
many people have put in the effort to make the tasks easier.
<p>
Ant can <a href="manual/CoreTasks/jar.html">Jar</a>, <a href= "manual/CoreTasks/tar.html">
Tar</a> or <a href="manual/CoreTasks/zip.html">Zip</a> files for deployment, while
the <a href="manual/CoreTasks/war.html">War</a> task extends the jar task for
better servlet deployment. <a href = "jlink.html" >Jlink</a> is a jar
generation file which lets you merge multiple sub jars. This is ideal
for a build process in which separate jars are generated by sub
Ant can <a href="manual/CoreTasks/jar.html">Jar</a>, <a href=
"manual/CoreTasks/tar.html"> Tar</a> or <a
href="manual/CoreTasks/zip.html">Zip</a> files for deployment, while the
<a href="manual/CoreTasks/war.html">War</a> task extends the jar task
for better servlet deployment. <a href = "jlink.html" >Jlink</a> is a
jar generation file which lets you merge multiple sub jars. This is
ideal for a build process in which separate jars are generated by sub
projects, yet the final output is a merged jar. <a href=
"manual/OptionalTasks/cab.html">Cab</a> can be used on Win32 boxes to build a cab file
which is useful if you have to target IE deployment.
"manual/OptionalTasks/cab.html">Cab</a> can be used on Win32 boxes to
build a cab file which is useful if you still have to target IE deployment.
<p>
@@ -350,17 +409,24 @@ The <a href = "index.html#ftp">ftp</a> task lets you move stuff up to a
server. Beware of putting the ftp password in the build file -a property
file with tight access control is slightly better. The <a href=
"manual/CoreTasks/fixcrlf.html">FixCRLF task</a> is often a useful interim step if
you need to ensure that files have u nix file extensions before upload. A
you need to ensure that files have U nix file extensions before upload. A
WebDav task has long been discussed, which would provide a more secure
upload to web servers, but it is still in the todo list. Rumour has it
that there is such a task in the jakarta-slide libraries.
that there is such a task in the jakarta-slide libraries. With MacOS X,
Linux and Windows XP all supporting WebDAV file systems, you may even be able
to use <a href="manual/CoreTasks/copy.html"><copy></a> to deploy
though a firewall.
<p>
EJB deployment is aided by the <a href="manual/OptionalTasks/ejb.html">ejb tasks</a>. At the
time of writing, only WebLogic was supported with these tasks -if your
EJB server is not supported, extending the ejb tasks would benefit your
project and the rest of the ant community.
EJB deployment is aided by the <a href="manual/OptionalTasks/ejb.html">ejb tasks</a>,
while the
<a
href="manual/OptionalTasks/serverdeploy.html"><serverdeploy></a>
suite can deploy to multiple servers. The popularity of Ant has
encouraged vendors to produce their own deployment tasks which they
redistribute with their servers. For example, the Tomcat4.1 installation
includes tasks to deploy, undeploy and reload web applications.
<p>
@@ -369,8 +435,13 @@ destination using <a href="manual/CoreTasks/copy.html">Copy</a> and <a href =
"index.html#copydir">Copydir</a> , or just sending them to a person or
process using <a href= "manual/CoreTasks/mail.html">Mail</a> or the attachment
aware <a href= "manual/OptionalTasks/mimemail.html">MimeMail</a>.
In one project our team even used ant to build CD images through a build followed
by a long set of Copy tasks, which worked surprisingly well.
In one project our team even used Ant to build CD images through a build followed
by a long set of Copy tasks, which worked surprisingly well, certainly
easier than when we mailed them to the free email service on
myrealbox.com, then pulled them down from the far end's web browser, which we
were running over WinNT remote desktop connection, that being tunneled
through SSH.
<a name="directories">
<h2> Directory Structures</h2>
</a>
@@ -386,44 +457,44 @@ another, and easy to clean up when desired.
The project contains sub directories
<table width="100%">
<tr>
<td><b>bin</b>
</td>
<td>common binaries, scripts -put this on the path.
</td>
<td><b>bin</b>
</td>
<td>common binaries, scripts -put this on the path.
</td>
</tr>
<tr>
<td><b>build</b>
</td>
<td>This is the tree for building; a nt creates it and can empty it
in the 'clean' project.
</td>
<td><b>build</b>
</td>
<td>This is the tree for building; A nt creates it and can empty it
in the 'clean' project.
</td>
</tr>
<tr>
<td><b>dist</b>
</td>
<td>Distribution outputs go in here; the directory is created in a nt
and clean empties it out
</td>
<td><b>dist</b>
</td>
<td>Distribution outputs go in here; the directory is created in A nt
and clean empties it out
</td>
</tr>
<tr>
<td><b>doc</b>
</td>
<td>Hand crafted documentation
</td>
<td><b>doc</b>
</td>
<td>Hand crafted documentation
</td>
</tr>
<tr>
<td><b>lib</b>
</td>
<td>Imported Java libraries go in to this directory
</td>
<td><b>lib</b>
</td>
<td>Imported Java libraries go in to this directory
</td>
</tr>
<tr>
<td><b>src</b>
</td>
<td>source goes in under this tree <i>in a heirarchy which matches
the package names<i>. The dependency compilation of javac requires this.
</td>
<td><b>src</b>
</td>
<td>source goes in under this tree <i>in a heirarchy which matches
the package names<i>. The dependency rules of <javac> requires this.
</td>
</tr>
</table>
@@ -435,7 +506,7 @@ manifests, and a <tt>web</tt> folder for web content -JSP, html, images
and so on. Keeping the content in this folder (or sub heirarchy)
together makes it easier to test links before deployment. The actual
production of a deployment image -such as a war file- can be left to the
appropriate a nt task: there is no need to completely model your source tree
appropriate A nt task: there is no need to completely model your source tree
upon the deployment heirarchy.
<p>
@@ -499,17 +570,17 @@ refactor the project directory structures.
<a name="antupdate">
<h2>
Ant Update Policies
Ant Update Policies
</h2>
</a>
Once you start using a nt, you should have a policy on when and how the
Once you start using A nt, you should have a policy on when and how the
team updates their copies. A simple policy is "every official release
after whatever high stress milestone has pushed all unimportant tasks
(like sleep and seeing daylight) on the back burner". This insulates you
from the changes and occasional instabilities that a nt goes through
from the changes and occasional instabilities that A nt goes through
during development. Its main disadvantage is that it isolates you from
the new tasks and features that a nt is constantly adding.
the new tasks and features that A nt is constantly adding.
<p>
@@ -517,7 +588,7 @@ Often an update will require changes to the build.xml files. Most
changes are intended to be backwards compatible, but sometimes an
incompatible change turns out to be
necessary. That is why doing the update in the lull after a big
milestone is important. It is also why including a nt.jar and related
milestone is important. It is also why including A nt.jar and related
files in the CVS tree helps ensure that old versions of your software
can be still be built.
@@ -532,8 +603,8 @@ take this approach.
<p>
Once you start extending a nt with new tasks, it suddenly becomes much
more tempting to pull down regular builds. The most recent a nt builds
Once you start extending A nt with new tasks, it suddenly becomes much
more tempting to pull down regular builds. The most recent A nt builds
are invariably the the best platform for writing your extensions, as you
can take advantage of the regular enhancements to the foundational
classes. It also prevents you from wasting time working on something
@@ -546,9 +617,9 @@ task on Ant 0.8 in isolation, announcing its existence six months latter
and discovering that instead of adulation all you get are helpful
pointers to the existing implementation. The final benefit of being
involved with the process is that it makes it easier for your tasks to
be added with the ant CVS tree, bringing forward the date when a nt has
be added with the Ant CVS tree, bringing forward the date when A nt has
taken on all the changes you needed to make to get your project to work.
If that happens you can revert to an official a nt release, and get on
If that happens you can revert to an official A nt release, and get on
with all the other crises.
<p>
@@ -567,7 +638,7 @@ Installing with Ant.
</h2>
</a>
Because a nt can read environment variables, copy, unzip and delete files
Because A nt can read environment variables, copy, unzip and delete files
and make java and OS calls, it can be used for simple installation
tasks. For example, an installer for tomcat could extract the
environment variable TOMCAT_HOME, stop tomcat running, and copy a war
@@ -577,20 +648,20 @@ was wanted.
<p>
The advantage of using a nt is firstly that the same install targets
The advantage of using A nt is firstly that the same install targets
can be used from your local build files (via an <tt>ant</tt> invocation
of the install.xml file), and secondly that a basic install target is
quite easy to write. The disadvantages of this approach are that the
destination must have an up to date version of a nt correctly
pre-installed, and a nt doesn't allow you to handle failures well -and a
destination must have an up to date version of A nt correctly
pre-installed, and A nt doesn't allow you to handle failures well -and a
good installer is all about handling when things go wrong, from files
being in use to jar versions being different. This means that a nt is not
being in use to jar versions being different. This means that A nt is not
suited for shrink wrapped software, but it does work for deployment and
installation to your local servers.
<p>
One major build project I was involved in had an a nt install build file
One major build project I was involved in had an A nt install build file
for the bluestone application server, which would shutdown all four
instances of the app server on a single machine, copy the new version of
the war file (with datestamp and buildstamp) to an archive directory,
@@ -601,32 +672,37 @@ firewall, we upped the ante in the deployment process by using the ftp
task to copy out the war and build files, then the telnet task to
remotely invoke the build file. The result was we had automated
recompile and redeploy to local servers from inside our IDE (Jedit) or
the command line, which was simply invalualbe.
the command line, which was simply invaluable. Imagine pressing a button
on your IDE toolbar to build, unit test, deploy and then functional test
your webapp.
<p>
One extra trick I added later was a junit test case to run through
the install check list. With tests to verify access permissions on network
drives, approximate clock synchronisation between servers, DNS functionality,
ability to spawn executables and all the other trouble spots
, the install script could automatically do
a system health test during install time and report problems. [The same tests
could also be invoked from a JMX MBean, but that's another story].
One extra trick I added later was a junit test case to run through the
install check list. With tests to verify access permissions on network
drives, approximate clock synchronisation between servers, DNS
functionality, ability to spawn executables and all the other trouble
spots, the install script could automatically do a system health test
during install time and report problems. [The same tests could also be
invoked from a JMX MBean, but that's another story].
<p>
So, a nt is not a substitute for a real installer tool, except in the
So, A nt is not a substitute for a real installer tool, except in the
special case of servers you control, but in that context it does let
you integrate remote installation with your build.
<a name="tips">
<h2>
Tips and Tricks</h2>
</a>
<dl>
<dt><b>
get
get
</b><dd>
The <a href="manual/CoreTasks/get.html">get</a> task can fetch any URL, so be used
The <a href="manual/CoreTasks/get.html">< get> </a> task can fetch any URL, so be used
to trigger remote server side code during the build process, from remote
server restarts to sending SMS/pager messages to the developer
cellphones.
@@ -678,7 +754,7 @@ You can import XML files into a build file using the XML parser itself.
This lets a multi-project development program share code through reference,
rather than cut and paste re-use. It also lets one build up a file of
standard tasks which can be reused over time. Because the import
mechanism is at a level below which a nt is aware, treat it as
mechanism is at a level below which A nt is aware, treat it as
equivalent to the #include mechanism of the 'legacy' languages C and
C++.
@@ -688,15 +764,13 @@ There are two inclusion mechanisms, an ugly one for all parsers and a
clean one. For now, the ugly
method is the most portable:-
<pre>
<!DOCTYPE project [
<!ENTITY IncludeBuildCore SYSTEM "buildCore.xml">
<!ENTITY IncludeBuildSecondary SYSTEM "buildSecondary.xml">
]>
<target name="includedBuild">
&IncludeBuildCore;
&IncludeBuildSecondary;
</target>
<!DOCTYPE project [
<!ENTITY propertiesAndPaths SYSTEM "propertiesAndPaths.xml">
<!ENTITY taskdefs SYSTEM "taskdefs.xml">
]>
&propertiesAndPaths;
&taskdefs;
</pre>
The cleaner method using XInclude/Xpath will let you include named
targets from one build file or another, using
@@ -704,27 +778,40 @@ targets from one build file or another, using
the xpointer syntax</a>. You'll need to wait for the W3C proposals
to finalise and the java XML parsers to implement it before
using xpointer references.
<p>
Before you go overboard with using XML inclusion, note that the <tt>ant</tt> task lets
you call any target in any other build file -with all your property settings propagating down to
that target. So you can actually have a suite of utility targets -"deploy-to-stack-a", "email-to-team",
"cleanup-installation" which can be called from any of your main build files, perhaps with subtly changed
parameters. Indeed, after a couple of projects you may be able to create a re-usable core build file which
contains the core targets of a basic java development project -compile, debug, deploy- which project specific
Before you go overboard with using XML inclusion, note that the
<tt><ant></tt> task lets you call any target in any other build
file -with all your property settings propagating down to that target.
So you can actually have a suite of utility targets
-"deploy-to-stack-a", "email-to-team", "cleanup-installation" which can
be called from any of your main build files, perhaps with subtly changed
parameters. Indeed, after a couple of projects you may be able to create
a re-usable core build file which contains the core targets of a basic
Java development project -compile, debug, deploy- which project specific
build files call with their own settings. If you can achive this then
you are definately making your way up the software maturity ladder. NB,
<tt>ant</tt> copies all your properties unless the <i>inheritall</i> attribute is set to false. Before that
attribute existed you had to carefully name all property definitions in all build files to prevent unintentional
overwriting of the invoked property by that of the caller, now you just have to remember to set
<tt>inheritall="false"</tt> on all uses of the ant task.
you are definately making your way up the software maturity ladder. With
a bit of work you may progress from being a SEI CMM Level 0 organisation
"Individual Heroics are not enough" to SEI CMM Level 1, "Projects only
succeed due to individual heroics"
<p>
NB, <tt><ant></tt> copies all your properties unless the
<i>inheritall</i> attribute is set to false. Before that attribute
existed you had to carefully name all property definitions in all build
files to prevent unintentional overwriting of the invoked property by
that of the caller, now you just have to remember to set
<tt>inheritall="false"</tt> on all uses of the <ant> task.
<dt><b>
Implement complex Ant builds through XSL
</b><dd>
XSLT can be used to dynamically generate build.xml files from a source
xml file, with the <a href="manual/CoreTasks/style.html">Style</a> task controlling
xml file, with the <a href="manual/CoreTasks/style.html"><xslt> </a> task controlling
the transform. This is the current recommended strategy for creating
complex build files dynamically. However, its use is still apparently
quite rare -which means you will be on the bleeding edge of technology.
@@ -735,7 +822,7 @@ Change the invocation scripts
</b><dd>
By writing your own invocation script -using the DOS, Unix or Perl
script as a starting point- you can modify a ant behavior for an
script as a starting point- you can modify Ant's settings and behavior for an
individual project. For example, you can use an alternate variable to
ANT_HOME as the base, extend the classpath differently, or dynamically
create a new command line property 'project.interfaces' from all .jar
@@ -744,13 +831,13 @@ files in an interfaces directory.
<p>
Having a custom invocation script which runs off a CVS controlled
library tree under PROJECT_HOME also lets you control a nt versions
across the team -developers can have other copies of a nt if they want,
library tree under PROJECT_HOME also lets you control A nt versions
across the team -developers can have other copies of A nt if they want,
but the CVS tree always contains the jar set used to build your project.
<p>
You can also write wrapper scripts which invoke the existing a nt
You can also write wrapper scripts which invoke the existing A nt
scripts. This is an easy way to extend them. The wrapper scripts can add
extra definitions and name explicit targets, redefine ANT_HOME and
generally make development easier. Note that "ant" in Windows is really
@@ -764,53 +851,67 @@ Write all code so that it can be called from Ant
This seems a bit strange and idealistic, but what it means is that you should
write all your java code as if it may be called as a library at some point in
future. So do not place calls to <b>System.exit()</b > deep in the code -if you
future. So do not place calls to <tt>System.exit()</tt > deep in the code -if you
want to exit a few functions in, raise an exception instead and have
<b>main()</b > deal with it.
<tt>main()</tt > deal with it.
<dt><b>
<p>
Moving one step further, consider proving an Ant Task interface to the
code as a secondary, primary or even sole interface to the
functionality. Ant actually makes a great bootloader for Java apps as it
handles classpath setup, and you can re-use all the built in tasks for
preamble and postamble work. Some projects, such as
<a href="http://xdoclet.sf.net">XDoclet</a> only run under Ant, because
that is the right place to be.
<!-- <dt><b>
Use Antidote as the invocation tool
</b><dd>
Even if you edit ant files by hand, Antidote makes a good execution tool
Even if you edit A nt files by hand, Antidote makes a good execution tool
because it eliminates the startup time of the JVM, perhaps even some of
the XML parsing delays.
-->
<dt><b>
Use the replace task to programmatic modify text files in your project.
</b><dd>
Imagine your project has some source files -BAT files, ASP pages (!), anything
Imagine your project has some source files -BAT files, ASPX pages (!), anything
which needs to be statically customised at compile time for particular
installations, such driven from some properties of the project such as JVM options, or the URL
to direct errors too. The replace task can be used to modify files, substituting text and creating
versions customised for that build or destination. Of course, per-destination customisation
should be delayed until installation, but if you are using a nt for the remote installation
should be delayed until installation, but if you are using A nt for the remote installation
that suddenly becomes feasible.
<dt><b>
Use the mailing lists
</b><dd>
There are two
<a href="http://jakarta.apache.org/site/mail.html">mailing lists</a>
related to a nt, ant-user and ant-developer. Ant user is where <i>all</i>
questions related to using a nt should go. Installation, syntax, code
related to A nt, ant-user and ant-developer. Ant user is where <i>all</i>
questions related to using A nt should go. Installation, syntax, code
samples, etc -post your questions there or search the archives for
whether the query has been posted and answered before. Ant-developer
is where a nt development takes place -so it is <i>not</i> the place to
is where A nt development takes place -so it is <i>not</i> the place to
post things like "I get a compilation error when I build my project" or
"how do I make a zip file". If you are actually extending a nt, on the other
"how do I make a zip file". If you are actually extending A nt, on the other
hand, it is the ideal place to ask questions about how to add new tasks, make
changes to existing ones -and to post the results of your work, if you want them
incorporated into the a nt source tree.
incorporated into the A nt source tree.
</dl>
<a name="puttingtogether">
<h2>
Putting it all together
</h2>
<h2>
Putting it all together
</h2>
</a>
What does an a nt build process look like in this world? Assuming a
What does an A nt build process look like in this world? Assuming a
single directory structure for simplicity, the build file
should contain a number of top level targets
<ul>
@@ -840,27 +941,53 @@ Internal targets should be used to structure the process
<ul>
<li> init - initialise properties, extra-tasks, read in per-user
property files.
<li> init-debug - initialise debug properties
<li> init-release - initialise release properties
<li> compile - do the actual compilation
<li> link/jar - make the jars or equivalent
<li> staging - any pre-deployment process in which the output is dropped
off then tested before being moved to the production site.
off then tested before being moved to the production site.
</ul>
The switching between debug and release can be done using the 'if' and
'unless' conditional flags on the targets, so that debug gets called
unless 'project.mode.release' is defined.
The switching between debug and release can be done by making
init-release conditional on a property, such as <tt>release.build</tt>
being set :-
<pre><target name="init-release" if="release.build">
<property name="build.debuglevel" value="lines,source"/>
</target>
</pre>
You then have dependent targets, such as "compile", depend on this
conditional target; there the 'default' properties are set, and then the
property is actually used. Because Ant properties are <i>immutable</i>,
if the release target was executed its settings will override the
default values:
<pre><target name="compile" depends="init,init-release">
<property name="build.debuglevel" value="lines,vars,source"/>
<echo>debug level=${build.debuglevel}</echo>
<javac destdir="${build.classes.dir}"
debug="true"
debuglevel="${build.debuglevel}"
includeAntRuntime="false"
srcdir="src">
<classpath refid="compile.classpath"/>
</javac>
</target>
</pre>
As a result, we now have a build where the release mode only includes
the filename and line debug information (useful for bug reports), while
the development system included variables too.
<p>
It is useful to define a project name property which can be echoed in
the init task. This lets you work out which ant file is breaking in a
the init task. This lets you work out which A nt file is breaking in a
multi file build.
<p>
What goes in to the internal ant tasks depends on your own projects. One
What goes in to the internal A nt tasks depends on your own projects. One
very important tactic is 'keep path redefinition down through
references' - you can reuse paths by giving them an ID and then
referring to them via the 'refid' attribute you should only need to
@@ -869,7 +996,7 @@ similarly.
<p>
Once you have set up the directory structures, and defined the a nt tasks
Once you have set up the directory structures, and defined the A nt tasks
it is time to start coding. An early priority must be to set up the
automated test process, as that not only helps ensures that the code
works, it verifies that the build process is working.
@@ -888,7 +1015,7 @@ system is often much harder work.
<h2>The Limits of Ant</h2>
Before you start adopting a nt as the sole mechanism for the build
Before you start adopting A nt as the sole mechanism for the build
process, you need to be aware of what it doesn't do.
<p>
@@ -905,15 +1032,15 @@ conditional statements.
If your build needs to handle exceptions then look at the sound listener
as a simple example of how to write your own listener class. Complex
conditional statements can be handled by having something else do the
tests and then build the appropriate a nt task. XSLT can be used for
tests and then build the appropriate A nt task. XSLT can be used for
this.
<h3>It's not Make</h3>
Some of the features of make, specifically inference rules and
dependency checking are not included in a nt. That's because they are
dependency checking are not included in A nt. That's because they are
'different' ways of doing a build. Make requires you to state
dependencies and the build steps, a nt wants you to state tasks and the
dependencies and the build steps, A nt wants you to state tasks and the
order between them, the tasks themselves can do depedency checking or
not. A full java build using Jikes is so fast that dependency checking
is relatively moot, while many of the other tasks (but not all), compare
@@ -924,7 +1051,7 @@ before acting.
XML isn't a nice representation of information for humans. It's a
reasonable representation for programs, and text editors and source code
management systems can all handle it nicely. But a complex a nt file can
management systems can all handle it nicely. But a complex A nt file can
get ugly because XML is a bit ugly, and a complex build is, well,
complicated. Use XML comments so that the file you wrote last month
still makes sense when you get back to it, and use Antidote to edit the
@@ -946,7 +1073,7 @@ use, what the common targets, what property names and files should be
and generally oversee the sub projects build processes. On a small project,
you don't need to do that -but remember: small projects become big projects
when you aren't looking. If you start off with a little bit of process, then
you can scale it if needed. F f you start with none, by the time you need
you can scale it if needed. I f you start with none, by the time you need
it it will be too late.
<h3>You still need all the other foundational bits of a software
@@ -956,8 +1083,8 @@ If you don't have an source code management system, you are going to end
up hosed. If you don't have everything under SCM, including web pages,
dependent jars, installation files, you are still going to end up hosed,
it's just a question of when it's going to happen.
CVS is effectively free and works well with a nt, but Sourcesafe, Perforce,
Clearcase and StarTeam also have a nt tasks. These tasks
CVS is effectively free and works well with A nt, but Sourcesafe, Perforce,
Clearcase and StarTeam also have A nt tasks. These tasks
let you have auto-incrementing build counters, and automated file
update processes.
@@ -965,7 +1092,7 @@ update processes.
You also need some kind of change control process, to resist
uncontrolled feature creep. Bugzilla is a simple and low cost tool for
this, using a nt and a continuous test process enables a rapid evolution of code
this, using A nt and a continuous test process enables a rapid evolution of code
to adapt to those changes which are inevitable.
<h2>Endpiece</h2>
@@ -987,13 +1114,25 @@ So get out there and have fun!
<li>
<a
href="http://www.martinfowler.com/articles/continuousIntegration.html">
Continuous Integration</a>; Martin Fowler. <br>
A paper on using a nt within a software project
<i> Continuous Integration</i> </a>; Martin Fowler. <br>
A paper on using A nt within a software project
running a continuous integration/testing proces.
<li> Refactoring; Martin Fowler, ISBN: 0201485672 <br>
Covers JUnit as well as tactics for making some headway with the mess of
code you will soon have.
<li><i> Refactoring</i>; Martin Fowler, ISBN: 0201485672 <br>
Covers JUnit as well as tactics for making some headway with the mess of
code you will soon have.
<li><a href="http://manning.com/antbook/"><i>Java Development with
Ant</i></a>;
Erik Hatcher and Steve Loughran. <br>
Arguably the only book on Ant worth owning;
certainly it's the only one written by Ant developers.
<li>
<a href="http://www.iseran.com/Steve/papers/when_web_services_go_bad.html">
<i>When Web Services Go Bad</i></a>; Steve Loughran.<br>
One of the projects this paper is based on.
</ul>
<a name="author">
@@ -1002,13 +1141,18 @@ running a continuous integration/testing proces.
Steve Loughran is a research scientist at a corporate R&D lab,
currently on a sabbatical building production web services against
implausible deadlines for the fun of it. Because of those implausible
deadlines, email questions related to this document are generally, and
regretfully unwelcome, unless they are corrections to the content,
advanced discourse on how to evolve software engineering processes to
meet the next generation of challenges, or from someone he knows. Even
then, a timely response is unlikely. Please use the mailing lists
instead.
implausible deadlines for the fun of it. He is also a committer on
Apache Ant and Apache Axis, and co-author of
<a href="http://manning.com/antbook/"><i>Java Development with Ant</i></a>.
He thinks that if you liked this document you'll love that book because
it doesn't just explain Ant, it goes into processes, deployment and best practices
and other corners of stuff that really make Ant useful. (It would
have been easier to just rehash the manual, but that wouldn't have been
so useful or as much fun).
<p>
For questions related to this document, use the Ant mailing list.
<hr>
<p align="center">Copyright © 2000-2002 Apache Software Foundation. All rights
Steve Loughran