how to extend an already deployed application

[csabaszucs]

Hello JBoss Users,

we are developing a JBoss-based reporting application with a web ui to trigger report generation jobs. We have currently 10 different types of reports that can be generated by this application.
There is a requirement to let the end-user extend the application with new report types. So end users should be able to integrate new report types into the application in a hot deployment style, so without the demand of stopping/undeploying the application during the extension's time.

Is there any standard way/design pattern/solution to do this within JBoss?

(my very first unexperienced idea would be using JBoss OSGi: there would be an extension point for a new report type, and there would be one extension for every new report type or developing some specialised JBoss file scanner/deployment scanner is a feasible solution for that?).

Many thanks in advance!
Csaba

[alesj]

"CsabaSzucs" wrote:

Is there any standard way/design pattern/solution to do this within JBoss?

With JBoss flat CL model this is very easy to achieve.

e.g. see how we track Deployers against DeployersImpl
--> JBOSS_HOME\server\default\conf\bootstrap\deployers.xml

 <!-- Accept any implementor of deployer -->
 <incallback method="addDeployer"/>
 <uncallback method="removeDeployer"/>

Simply create and register some ReportRepository service against MC
and then track any newly deployed Reports via MC's incallback mechanism.
- http://java.dzone.com/articles/a-look-inside-jboss-microconta-0

[csabaszucs]

Hello again,

Thanks a lot for your fast help!

I started to read the JBoss Microcontainer User Guide: a really interesting runtime/component/deployment environment!

One question: may we use all the stuff you adviced me in JBoss 4.x or only in JBoss 5.y? Currently we are using JBoss 4.x.

Thanks!
Csaba

[alesj]

Only JBoss5.

You can also have a look at my MC demos project for more examples:
- http://anonsvn.jboss.org/repos/jbossas/projects/demos/microcontainer/trunk/

The whole project is fully Maven-ized,
so it's very simple to use it, play around, debug, ...

Once you grasp the concepts, you can easily apply them in JBoss5.

[csabaszucs]

Hello Ales,

so then I ask it in another way: is there any facility to hook on deployment callbacks /be notified about new deployments of applications, beans etc./ on JBoss 4.x?

I think implementing a ReportRepository service is not a problem in JBoss4.x.

I am not sure that we are allowed to shift to JBoss5.y nowadays...
Thanks again!

Csaba

[alesj]

"CsabaSzucs" wrote:

so then I ask it in another way: is there any facility to hook on deployment callbacks /be notified about new deployments of applications, beans etc./ on JBoss 4.x?

You can create your own deployer.

A deployer that would handle just particular type of deployments, matching on suffix.
e.g. my-new-report.rep or some-report.xml
Taking those services/beans from the deployment,
and handle them somehow - registering against ReportRegistry or whatever.

Try looking at the code for JBoss4.x, my spring-int module,
where I handle Spring specific deployments: .spring or -spring.xml.

[csabaszucs]

Ales,

How shall I extend JBoss deployment logics?
Based upon JBoss deployment SPI side or directly based upon the classes of SubDeployerSupport and the others like in the implementation of XSLSubDeployer?

So shall I implement my custom deployer class with the extension of org.jboss.deployment classes or with the extension of org.jboss.deployers.spi.deployer classes?

Thanks!
Csaba

[alesj]

It's been a while since I did 4.x deployers.
Like I said, try doing similar thing as I did for SpringDeployer.

If it was MC/AS5 I could help you a lot more. ;-)