Using Apache Ant with WLST

In this post I'll show you how to use Apache Ant (which ships with OBI 11g), and a tiny bit of batch scripting to run WebLogic Scripting Tool (WLST) scripts.

In my last blog post we looked at using the JConsole to view and invoke WebLogic MBean methods. JConsole is a nice way to get an overview of what WebLogic operations are available but what we really want to do is run some WebLogic tasks automatically! In this post I'll show you how to use Apache Ant (which ships with OBI 11g), and a tiny bit of batch scripting to run WebLogic Scripting Tool (WLST) scripts.

The WLST is designed for automating WebLogic tasks so we'll definitely be using this, but it's a scripting environment and not so much an automation tool. WLST doesn't really help us if we need to do some non-WebLogic tasks, that's where Apache Ant comes in. Ant is a Java based build automation tool which allows you to automate a range of tasks using XML 'build' files to describe the process. In this post we'll use Ant to run a WebLogic script that prints the status of the Oracle BI server, to do this you'll need to create three files.

Fig 1. Files required to run WLST from ANT

File 1 - RunScript.bat

This batch file enables us to set environment variables before making the call to Ant.

File 2 - AntSctipt.xml

This is the Ant build script which will be interacting with WLST. The RunScript.bat file above passes this file as a parameter to Ant.

File 3 - ServerStatus.py

This is the script that will be passed into WLST to print the status of the BI Server to the screen, it contains the Jython-like scripting language that WLST executes.

Now you might be thinking "why not just use a batch script to run WLST directly instead of using Ant?", well, you could do that but here are some of the benefits of using Ant:

• Ant is platform independent. If you write a batch script in Windows to do a bunch of pre/post WLST tasks you'd soon regret it if you needed to move the script to a Linux environment or vice-versa.
• It's a powerful, expressive tool. Batch/shell scripts can get messy quickly if you have a lot of tasks to perform whereas Ant is much cleaner and scalable with easy-to-use functions.
• Ant comes packaged with OBI 11g. If you've ever looked into the Windows OBIEE scripts then you’ve probably already noticed that it uses Ant to start/stop the OBI services, so there is no need to download any additional software.
• Oracle provides a custom Ant task for you. To make it easier to call WLST from an Ant script Oracle has implemented a custom Task Definition for you. To use the Task Definition you just need to define it in your Ant script and add the weblogic.jar file Oracle provides to the classpath (found in WL_HOME/server/lib).
• Ant is mature. Ant has been around for quite a while and has achieved widespread adoption, it's well documented and handles itself well if there's a problem.

If you take a peek into the Start/Stop BI Services icons in the start menu you will see that Ant is already being used to manage the BI Services in windows

Fig 2. OBIEE uses a pre-installed version of Ant to start and stop the BI Services

Okay so let's get into the fun stuff.

Here is a look at the RunScript.bat file, be sure to change the MW_HOME directory path to your own, you shouldn't have to change anything else:

@ECHO OFF

SETLOCAL

set MW_HOME=D:\oracle\obiee

set ANT_HOME=%MW_HOME%\modules\org.apache.ant_1.7.1

set JAVA_HOME=%MW_HOME%\Oracle_BI1\jdk

set weblogic.lib.dir=%MW_HOME%\wlserver_10.3\server\lib

%ANT_HOME%\bin\ant.bat -f AntScript2.xml -lib

%weblogic.lib.dir%\weblogic.jar && pause

As you can see above we are simply setting some environment variables and then executing Ant.bat with the XML build file as a parameter. We also add Oracle's weblogic.jar file to the classpath so that the Ant file knows how to communicate with WLST. Now let's have a look at the AntScript.xml file, if you have had any experience at all with Ant you will have no problem understanding the build script:

<?xml version="1.0" encoding="windows-1252" ?>

<project name="Run WLST project" default="run-wlst-script">

<property environment="env"/>

<taskdef name="wlst"

classname="weblogic.ant.taskdefs.management.WLSTTask"/>

<target name="run-wlst-script">

<wlst debug="false" failonerror="true" filename="ServerStatus.py">

</wlst>

</target>

</project>

Basically, this script creates a new task definition called wlst, which we use further down in the script, and provides the name of the class which implements it (weblogic.ant.taskdefs.management.WLSTTask). It then runs the WLST task with the ServerStatus.py script as a parameter, any code in the ServerStatus.py file will then be executed by the WLST. Note that for the sake of simplicity I have hard-coded the location of the ServerStatus.py file but you could pass this in as a parameter.

Okay so next is the ServerStatus.py file, this is where the actual WLST script goes. Make sure you use your own WebLogic username, password and URL instead of mine:

print "Connecting..."

connect('weblogic','welcome1','t3://localhost:7001')

domainCustom()

cd ('oracle.biee.admin')

print 'Connecing to BIInstance MBean'

cd ('oracle.biee.admin:type=BIDomain.BIInstance,biInstance=coreapplication,group=Service')

print 'BIInstance MBean; ServiceStatus: ' + get('ServiceStatus')

print 'Disconnecting...'

exit()

This is quite an easy script to understand if you've had any experience with WebLogic scripting. The script connects to the BI domain, navigates to the oracle.biee.admin MBean and gets the 'ServiceStatus' attribute, printing it out to the screen. Again, for simplicity I've hard-coded the username, password and WebLogic URL here but it would be a good idea to store these in a user-configuration file.

Now that all of the files have been created you can double click on the RunScript.bat file to see the status of the BI Server. Here is a look at the output:

Fig 3. Script output showing the status of the BI Server

Obviously you can do much more than simply printing the status of the BI server to the console - like uploading the BI Repository or bouncing the BI servers etc - but the purpose of this post was just to show you how to use Ant together with WLST. Have fun thinking of things to automate!

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