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Lightning fast portlet development with JRebel

July 22, 2011 By Neil Griffin

Back in April of this year I had the opportunity to speak at the CON-FESS conference in Vienna, Austria. One of the exhibitors there was zeroturnaround.com and I had the privilege of sitting next to founder Jevgeni Kabanov over dinner one night.

Jevgeni described the benefits of JRebel, a JVM-plugin that makes it possible for Java developers to instantly see any code change made to an app without redeploying. Needless to say, redeploying WARs is part of the very fabric of a Liferay portlet developer's life, so I knew that I had to give this product a try with my next ICEFaces 2 portlet with PortletFaces Bridge.

and to my utter amazement... IT WORKED!!!

Simply put, this product is a MUST HAVE for Liferay portlet developers. I'm hooked! Over the past 6 years of portlet development, this product could have saved me COUNTLESS hours of development time waiting for redeploys.

The JRebel documentation is quite good, but here are some quick instructions for how to get started with JRebel and the Liferay+Tomcat bundle:

  1. Download JRebel (30 day free trial)
  2. Install JRebel to it's default location. For example, on the Mac: /Applications/ZeroTurnaround/JRebel
  3. Set the REBEL_HOME environment variable. On the Mac, I find it's best to do this inside the $HOME/.MacOSX/environment.plist file: 
    <?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE plist PUBLIC "-//Apple Computer//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
<plist version="1.0"> <dict>
<key>REBEL_HOME</key>
<string>/Applications/ZeroTurnaround/JRebel</string>
</dict>
</plist>
  4. On Mac, add the following to the LIFERAY_HOME/tomcat/bin/setenv.sh script: 
    -javaagent:$REBEL_HOME/jrebel.jar
  5. On Windows, add the following to the LIFERAY_HOME/tomcat/bin/setenv.bat file: 
    -javaagent:%REBEL_HOME%\jrebel.jar
  6. Create a rebel.xml file that will be deployed in the runtime classpath of the WAR:Note that if you install the JRebel plugin for Eclipse, IntelliJ 8/9, IntelliJ X, or NetBeans) you can right click on the project and have the IDE generate the file. You can also generate the rebel.xml file with a Maven goal.
    • Maven: src/main/resources/rebel.xml
    • Liferay Plugins SDK: docroot/WEB-INF/src/rebel.xml
  7. Start Tomcat with the liferay/tomcat/bin/startup.sh script (startup.bat on Windows)
  8. Deploy the WAR to the Liferay /deploy folder
  9. Make some Java code changes to your app and click Save in your IDE
  10. Reload your browser, and voila! Instant changes! No redeploy!

 

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Showing 17 Comments

Xinsheng Robert Chen
Xinsheng Robert Chen
7/25/11 11:36 AM

It sounds very interesting. I will give it a try. Thank you!

Jan Gregor
Jan Gregor
7/26/11 5:53 AM

After some testing I must say, this is amazing! I am going to test it a bit deeper to see, whether it is usable for production and stable with different enviroments. If yes, then it is a huge move forward especially for portal development!

Jay Patel
Jay Patel
7/26/11 11:30 PM

This is good...thnx for Sharing...
Can we achieve the same for extension environment, apart from using reloadable=true?

Neil Griffin
Neil Griffin
7/27/11 2:46 AM

Since Liferay lives in a web application context (for example, webapps/ROOT under Tomcat), then JRebel should work just fine for EXT plugins. You would just need to add a rebel.xml file to the web application context in which Liferay is deployed.

8/3/11 9:30 AM

[...] If you look for official info in our documentation about JRebel supporting Liferay, you will not find it yet; we are working towards getting this more formalized in future JRebel releases. However,... [...] Read More

Petros Giakouvakis
Petros Giakouvakis
8/4/11 1:24 AM

Hi Neil, I tested JRebel myself just using the JRebel documentation offered during installation (which is really excellent I must say) and got Liferay working with JRebel and making use of the MVCPortlet as the base. Both the presenation jsp as well as the java classes are now instantly reloaded on the save of the content, but changing configuration files such as liferay-portlet.xml and portlet.xml still require a restart. Is this the same with you?
Regardless of this: JRebel seems to really speed up the development cycle that is sure. So thanks for this very inspiring post!

Jan Gregor
Jan Gregor
8/4/11 1:32 AM

Hi Petros,

I thinks this is ok, since these deployment descriptors are checked by each deployment of a plugin and thus the plugin must be re-deployed in order to see changes in mentioned descriptors. Anyways it would be nice to have a plugin for Liferay to enable hot-swap of these descriptor. I am not sure whether it will be possible on the Liferay part.

Neil Griffin
Neil Griffin
8/4/11 7:30 AM

@Petros: Jan is right -- it would be really nice to have portlet.xml and other descriptors get reloaded as well, but it is something I think we can live with. Perhaps this is something the folks at zeroturnaround.com could investigate as a feature.

Sampsa Sohlman
Sampsa Sohlman
8/10/11 4:46 AM

Actually, we have used this for years emoticon

Neil Griffin
Neil Griffin
8/10/11 7:30 AM

@Sampsa: Great to hear. JRebel must be the world's best kept secret!

Petros Giakouvakis
Petros Giakouvakis
8/11/11 4:03 PM

@Jan and Neil: thank you for the info. I can definitely live with this, as these changes don't occur al that often after all. I just wasn't sure if I might have made some JRebel configuration error. emoticon
I am definitely recommending JRebel from now on as is. :-)

Daniel Tomsu
Daniel Tomsu
9/7/11 7:30 AM

Hi Neil, thanks for the great post. I do have a slight problem though and was wondering if anyone else is in the same situation:

I do have the application running in the debug perspective of eclipse and starting with the registered server there, not with the bin/startup script. I disabled the automatic publishing, as it is recommended by the jRebel Feature.

The class changes are working just fine, but any jsp changes don't get deployed. Any help on that.

Thanks a lot.

Neil Griffin
Neil Griffin
9/8/11 6:41 AM

Hi Daniel. Thanks for the kind words. I normally do all my work with Facelets and so I haven't tried JSP. You might want to try the JRebel forums regarding that.

11/11/11 9:20 AM

[...] A few months ago, Neil Griffin posted a blog post about JRebel , which was the inspiration for me to dig into this tool a bit more and start using it. If you want to learn more about this tool, you... [...] Read More

1/3/12 6:27 AM

[...] Neil Griffin’s summer blog post about eliminating redeploys during Liferay portlet development was a great introduction to using JRebel and Liferay together. In November 2011, after having a few... [...] Read More

5/15/12 12:00 AM

[...] I would recommend that you read the blog post titled Lightning fast portlet development with JRebel. Flag Please sign in to flag this as inappropriate. Mark as an Answer [...] Read More

5/16/12 6:43 AM

[...] If you look for official info in our documentation about JRebel supporting Liferay, you will not find it yet; we are working towards getting this more formalized in future JRebel releases. However,... [...] Read More