Hot deployment – which consists in deploying an application without stopping the application server – can save a lot of time and of course, avoid interruption of service.
You may already know it, but Bonita Open Solution embeds Jetty when it comes to deploying your process-driven application. I tried to programmatically hot deploy an application with Jetty a few days ago but unfortunately didn’t find any documentation on how to do this. After a lot of trial and error, I finally did it! I was mainly inspired from the depths of a mailing-list archive (BTW when will we have a Jetty forum?). Here is the results of my research…
I found several ways to use hot deployment with Jetty, including:
- Context deployer. But this requires XML file configuration and replacing a war in a directory… and then waiting for a scan of the directory!!
- OSGI service. This seems to be a great and easy solution but it also seems to be only available for Jetty 7.
And now it’s high time to show you how to use hot deployment programmatically:
Note: As Bonita Open Solution is based on Eclipse 3.5, we are using Jetty version 6.
- Create the server:
1Server jetty = new Server();
- Create a handlerCollection with a ContextHandlerCollection in it:
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4HandlerCollection hc = new HandlerCollection ();
ContextHandlerCollection contextHandlerCollection = new ContextHandlerCollection();
hc.setHandlers(new Handler[]{contextHandlerCollection});
jetty.setHandler(hc); - Start the server:
1server.start();
- Hot deploy your web application:
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4WebAppContext warWebappContext = new WebAppContext();
//configure it ...
contextHandlerCollection.addHandler(warWebappContext);
warWebappContext.start(); - Hot undeploy your application:
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6//get the WebAppContext to undeploy...
WebAppContext toUndeploy = getWebAppContextToUndeploy();
//stop it
toUndeploy.stop();
//and remove it from the handler collection
contextHandlerCollection.removeHandler(toUndeploy);
In a nutshell, the trick is to use a HandlerCollection for your WebAppContextHandler.
I hope that this article will help others to hot deploy with Jetty. You’re welcome to suggest better ways or to provide links to good documentation on this subject!
#1 by Christopher Johnson on May 28th, 2010
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I have solved the problem of true hot deployment during a debug session using Eclipse, Jetty, and Maven. You can find instructions here:
http://www.clickonchris.com/2010/05/configuring-jetty-maven-and-eclipse-together-with-hot-deploy/
#2 by Aurelien Pupier on May 29th, 2010
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Hi,
Thanks for your pointer.
But you are doing an other thing. You are just running the Jetty server in remote debug mode. And not hot-deploying web application.
Regards
#3 by Sasha on July 9th, 2010
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I try same thing but I found one problem…
After redeploy I see increasing total loaded classes for approximation same count as my application and some additional threads…
#4 by Aurelien Pupier on July 9th, 2010
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Hi,
take care to release objects of your web applications when they stop.(I think in particular to classloader).
I can’t tell you more with no more precise information.
BTW, if you encounter memory issue, I can suggest you to use MAT (Memory Analyzer Tool): http://www.eclipse.org/mat/
Regards
#5 by Sasha on July 10th, 2010
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How I can know that it’s stop only application can release in correct way own objects
mmm….
Can I use destroy method of servlet for this job?..
#6 by Aurelien Pupier on July 13th, 2010
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You no more have “increasing total loaded classes for approximation same count as my application and some additional threads…” for instance
It might be a good place.
#7 by aqua on October 29th, 2010
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Pls let me know how am I supposed to deploy a project in eclipse to knopflerfish osgi which contains jsp pages. I have included html,jsp n servlets but jsps r just not working. when I open my page from the web browser, the jsp functionality fails to work out. html n servlet running fine.
regards