SVNAnt
SVNAnt is an Ant task allowing you to interact with Subversion within the convenience of your Ant build script. No more writing custom scripts to get the revision of your repository to tag your release jars. Nor do you have to make command line calls to checkout your latest and greatest as part of your continuous integration process. With SVNAnt, you have the familiarity of the Ant syntax and the flexibility you need for interacting with Subversion.
Features
SVNAnt is a full-featured Subversion client capable of using the native Java bindings or command-line wrappering depending on which is available. Beyond how it works, SVNAnt allows you to do all svn subcommands but the following:

If the svn subcommand is not listed here, you can use it in your Ant build file. Before we continue start using SVNAnt, we have to install it and configure Ant to use it.
Installation
Now that we know what SVNAnt is and what its features are, lets install SVNAnt so that you can begin to use SVNAnt to access Subversion within your Ant build cycle.

Step 1. (Download, Compile and Extract)
This step will download, compile, and "install" the latest version of SVNAnt.
1.1 Using Subversion, checkout the SVNAnt project located here: http://subclipse.tigris.org/svn/subclipse/trunk/svnant
1.2 From the command line, while inside of the location where you checked out SVNAnt to, run "ant makeDistrib"
1.3 Extract the .zip file created in the build directory of your SVNAnt source to a location of your choosing

Step 2. (Modify your build.xml)
The next step is to tell Ant how to find your SVNAnt task by adding the following to your build.xml file:
<path id= "svnant.classpath" >
     <fileset dir= "/PATH/TO/YOUR/EXTRACTED/SVNANT-ZIP" >
         <include name= "*.jar" />
     </fileset>
</path>

<typedef resource="org/tigris/subversion/svnant/svnantlib.xml" classpathref="/svnant.classpath" />
That should be it. I know that it appears to be too good to be true so lets verify this.

Step 3. (Verify installation)
Building upon Step 2, lets create a new ant task that will use the wcVersion feature of SVNAnt to get some information about your repository from a local working copy:
<target name="testSVNAnt">
     <svn>
         <wcVersion path= "PATH/TO/YOUR/WORKINGCOPY" />
     </svn>

     <echo message= "Subversion repository url: ${repository.url}" />
</target>
(Note: In the event that you need to pass credentials to Subversion, look here.)
The output should be something similar to this:
$ ant testSVNAnt

Buildfile: build.xml

testSVNAnt:
      [svn] <WcVersion> started ...
      [svn]  finished.
     [echo] Subversion repository url: http://svn.apache.org/repos/asf/incubator/openejb/trunk

BUILD SUCCESSFUL
Total time: 43 seconds

Pat yourself on the back. You have successfully installed SVNAnt and you are ready to implement Subversion into your Ant build cycle. Instead of us going through each available feature for SVNAnt, please view the SVNAnt Documentation. Now lets talk about why you may want to use SVNAnt to allow for Subversion interaction inside of your Ant build cycle.

Usage of ANT_OPTS in Ant Script | ANT_OPTS capabilities

Ant has three environment variables that you can use to set its default behavior.
• ANT_ARGS Set this variable to include those options you use frequently.
• ANT_OPTS is a list of arguments that you want to pass to the JVM that will run Ant.
• JAVACMD is the absolute path to the Java executable you want Ant to use. you may specify a value for the JAVACMD environment variable. This defaults to %JAVA_HOME%\bin\java, typically invoking the JVM provided in Sun's Java Development Kit. Ant provides JAVACMD for those who wish to specify an alternate JVM. full path of the Java executable. Use this to invoke a different JVM than JAVA_HOME/bin/java(.exe).

These are useful environment variables that the Ant wrapper scripts use when
invoking Ant: ANT_OPTS and ANT_ARGS. Neither of these is typically set by users,
but each can provide value for certain situations.

The ANT_OPTS environment variable provides options to the JVM executing Ant,
such as system properties and memory configuration. ANT_OPTS - command-line arguments that should be passed to the JVM. For example, you can define system properties or set the maximum Java heap size here.

For authenticated proxy:
Set your ANT_OPTS environment variable to configure your proxy if you have one. For instance:
set ANT_OPTS=-Dhttp.proxyHost=myproxy -Dhttp.proxyPort=3128

You can set these properties by either modifying Ant's startup script, or by
using the ANT_OPTS environment variable. The following example shows the Windows commands to specify these properties using ANT_OPTS, and then to invoke Ant:
set ANT_OPTS=-DproxySet=true -DproxyHost=localhost -DproxyPort=80
ant mytarget
The same trick works on Unix, although the syntax is slightly different depending on which
shell you use:
$ export ANT_OPTS="-DproxySet=true -DproxyHost=localhost -DproxyPort=80"
$ ant mytarget

set ANT_OPTS=-Dhttp.proxyHost=myproxyhost -Dhttp.proxyPort=8080 -Dhttp.proxyUserName=myproxyusername -Dhttp.proxyPassword=myproxypassword -Dhttps.proxyHost=myproxyhost -Dhttps.proxyPort=8080

Use ANT_OPTS to control Ant’s virtual machine settings.
Some tasks may require more memory, which you can set in the ANT_OPTS environment variable, using the appropriate mechanism for your platform:
set ANT_OPTS=-Xmx500M
export ANT_OPTS=-Xmx500M

Setting the maximum heap size is another common use of ANT_OPTS. Here is how we set the maximum size to 128 MB when using Sun's JDK:
set ANT_OPTS=-Xmx128m

One environment variable you may wish to set is ANT_OPTS. The value of this variable is passed as a JVM argument. Specifying system properties is a common use. In this simple
example, we pass the log.dir system property to the JVM running Ant:
$ set ANT_OPTS=-Dlog.dir=C:\logs
$ ant run
Now this property is available within the buildfile, for instance:
<echo>Log directory is set to: ${log.dir}</echo>
If the buildfile runs a Java application, the property may be retrieved from within it as
follows:
String logDir = System.getProperty("log.dir");

Troubleshoot: Illegal Java options in the ANT_OPTS variable
The environment variable ANT_OPTS provides a means to pass options into Ant,
such as a permanent definition of some properties, or the memory parameters for
Java. The variable must contain only options the local JVM recognizes. Any invalid
parameter will generate an error message such as the following (where ANT_OPTS was
set to –3):
Unrecognized option: -3
Could not create the Java virtual machine.

If the variable contains a string that is mistaken for the name of the Java class to run
as the main class, then a different error appears:

Exception in thread "main" java.lang.NoClassDefFoundError: error-string
Test: Examine ANT_OPTS and verify that the variable is unset or contains valid
JVM options.
Fix: Correct or clear the variable.

Power Point PPT: Introduction of Apache Ant

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