Distributed Groovy in 5 minutes

Ok Groovy is cool, but can your Groovy do this?



This took me about 20 minutes to do with Terracotta.  If you're not new to Terracotta, this is pretty old hat.  Distributing a LinkedBlockingQueue is really easy (as seen above).  But then again, being able to use Groovy to distribute anything in Java is ... well pretty powerful.

What if you wanted to synchronize two scripts?  Just use a java.util.concurrent.CyclicBarrier:



I could build a distributed test harness in ... oh I don't know another 10 minutes.  But I'll leave that up to you :).

Here's how to get going with Clustered Groovy:

1) Download and unpack Groovy.
2) Set GROOVY_HOME (per their instructions)
3) Download and unpack Terracotta. (Hint: get Version 2.4.  If it's not already final, it will be soon)
4) set TC_HOME (this makes your life easier)
5) You need my Groovy Startup Script - I saved it as groovyConsoleTC.  Sorry, I use a Mac so it is not Windows friendly, but at 5 lines, hopefully you can figure it out:

DIRNAME=`dirname "$0"`

TC_INSTALL_DIR=${TC_HOME}
. "${TC_INSTALL_DIR}/bin/dso-env.sh" -q $DIRNAME/groovy-tc.xml
JAVA_OPTS=$TC_JAVA_OPTS
echo $JAVA_OPTS

. "${GROOVY_HOME}/bin/startGroovy"

startGroovy groovy.ui.Console "$@"


6) You need my RootMap class.  It's not that pretty, it could be improved, but it works:

import java.util.*;
import java.util.concurrent.*;

public class RootMap
{
  public final Map root = new ConcurrentHashMap();
}

7) You need my Terracotta config (save it to a file called groovy-tc.xml)

<?xml version="1.0" encoding="UTF-8"?>
<!--

 All content copyright (c) 2003-2007 Terracotta, Inc.,
 except as may otherwise be noted in a separate copyright notice.
 All rights reserved.

-->
<tc:tc-config xmlns:tc="http://www.terracotta.org/config"
 xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
 xsi:schemaLocation="http://www.terracotta.org/schema/terracotta-4.xsd">
 <servers>
   <server host="%i" name="sample"/>
 </servers>
 <system>
   <configuration-model>development</configuration-model>
 </system>

 <application>
   <dso>
     <instrumented-classes>
       <include>
         <class-expression>Root*</class-expression>
         <honor-transient>true</honor-transient>
       </include>
     </instrumented-classes>
     <locks>
       <autolock>
         <method-expression>* *..*.*(..)</method-expression>
       </autolock>
     </locks>
     <roots>
       <root>
         <field-name>RootMap.root</field-name>
       </root>
     </roots>
   </dso>
 </application>
</tc:tc-config>

If you saved all that to some directory, now:

8) Compile RootMap.java : > javac RootMap.java
9) Make sure your classpath has . in it: > export CLASSPATH=.
10) start up the TC Server in $TC_HOME/bin/start-tc-server.sh
11) start one ore more Groovy Consoles using groovyConsoleTC

Validate you can see a root by executing a Groovy script:

root = new RootMap()
root.root.put("message", "Hello World")

If you run the admin console, you can see your root:

> $TC_HOME/bin/admin.sh

Now try out more advanced stuff like LinkedBlockingQueue!

Update: I've added a tar.gz file with the relevant code: distributedGroovy.tgz