OJB throws OJBRuntimeException if two applications are deployed on AppServer

[Rick <ri...@merindus.com>]

Hi,

We have developed two applications. Both use OJB for persistence. When we 
deploy them together on Sun One Application server, we find the one deployed 
last doesn't work. It throws the org.apache.ojb.broker.OJBRuntimeException 
exception when trying to load the objects that represent the tables in the 
database.

We searched around a little and found this occurs in the Orion application 
server as well.

Could anyone suggest any steps to be taken to get around this problem?

By the way, we rebuild our applications as .WAR files, deployed them on Tomcat 
and found them to work fine.

Here's (part of) the stack trace from Sun One:

Root Cause 
org.apache.ojb.broker.OJBRuntimeException: Class, TCIS_ASC.valueobject.Person, 
could not be found.
	at 
org.apache.ojb.broker.metadata.DescriptorRepository.discoverDescriptor(Unknown 
Source)
	at org.apache.ojb.broker.metadata.DescriptorRepository.getDescriptorFor
(Unknown Source)
	at org.apache.ojb.broker.metadata.DescriptorRepository.getDescriptorFor
(Unknown Source)
	at org.apache.ojb.broker.core.PersistenceBrokerImpl.getIteratorByQuery
(Unknown Source)
	at 
org.apache.ojb.broker.core.DelegatingPersistenceBroker.getIteratorByQuery
(Unknown Source)
	at 
org.apache.ojb.broker.core.DelegatingPersistenceBroker.getIteratorByQuery
(Unknown Source)
	at TCIS_ASC.dataaccess.ApplicationOJBDAO.getAllApplications
(ApplicationOJBDAO.java:97)
	at TCIS_ASC.service.SearchService.searchApplicant
(SearchService.java:64)
	at TCIS_ASC.action.AppStatusSearchAction.execute
(AppStatusSearchAction.java:79)
	at org.apache.struts.action.RequestProcessor.processActionPerform
(RequestProcessor.

Caused by: java.lang.ClassNotFoundException: TCIS_ASC.valueobject.Person
	at java.net.URLClassLoader$1.run(URLClassLoader.java:198)
	at java.security.AccessController.doPrivileged(Native Method)
	at java.net.URLClassLoader.findClass(URLClassLoader.java:186)
	at java.lang.ClassLoader.loadClass(ClassLoader.java:299)
	at java.lang.ClassLoader.loadClass(ClassLoader.java:255)
	at java.lang.ClassLoader.loadClassInternal(ClassLoader.java:315)
	at java.lang.Class.forName0(Native Method)
	at java.lang.Class.forName(Class.java:140)


Thanks & Regards

Rick



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Re: OJB throws OJBRuntimeException if two applications are deployed on AppServer

[Martin Kalén <ma...@curalia.se>]

Rick wrote:

> We have developed two applications. Both use OJB for persistence. When we 
> deploy them together on Sun One Application server, we find the one deployed 
> last doesn't work.
[...]
> By the way, we rebuild our applications as .WAR files, deployed them on Tomcat 
> and found them to work fine.

WAR files deployed in Tomcat will run as two separate servlet instances 
with two separate class-loaders (loading OJB from each webapps 
WEB-INF/lib and/or WEB-INF/classes).

It looks like your deployment in Sun One Application Server loads OJB 
with the same class-loader, which will give you headaches if trying to 
use two different repository-mappings and/or different OJB.properties.

When OJB is first referenced it will bootstrap it's metadata manager and 
statically load OJB.properties, which in turn references the 
repository-files that are also loaded statically. I.e. "first 
application wins" in your scenario.

To overcome this you can either try to separate class-loading between 
your apps in Sun One or use OJB profiles to load the repository on a 
per-thread-basis at runtime.

For more on OJB profiles, see e.g.
http://nagoya.apache.org/eyebrowse/ReadMsg?listName=ojb-user@db.apache.org&msgNo=9705
In that mail I outline how we use OJB with an empty global (static) 
repository and load the correct class-descriptors from the thread that 
needs them.

With this pattern we can run a Cocoon-servlet in Tomcat, use only one 
OJB instance in cocoon/WEB-INF/lib, but still have multiple Cocoon 
"applications" in sub-sitemaps running with separate repository 
descriptors and class-mappings.

-- 
Martin Kalén
Curalia AB              Web:  http://www.curalia.se
Orrspelsvägen 2B        Mail: info@curalia.se
SE-182 79  Stocksund    Tel:  +46-8-410 064 40


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