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From j...@apache.org
Subject [jira] Commented: (JS2-56) Objects Fail to Create with Tomcat Classloaders and cross context
Date Fri, 28 May 2004 17:47:07 GMT
The following comment has been added to this issue:

     Author: David Sean Taylor
    Created: Fri, 28 May 2004 10:45 AM
" Instead of commons, I would prefer creating an om sub-project instead of cluttering commons
with implentation classes. Waddya think"

I think we need to clearly define what new jars we are proposing.
Currently, we the commons jar.
It has OM interfaces and implementations.
It also has a dual purpose of providing portal/portlet-application communications.
I proposed pulling out the p/pa comm code into a new project:


Finally, there is the util directory o.a.j.util under commons

So we would now have 3 sub-projects out of commons:

1. jetspeed-om (om interfaces and implementations)
2. jetspeed-core-pa (JS2-37)
3. jetspeed-commons (basically just o.a.j.util)

Im wondering if we even need #3 ....perhaps they can be moved into #2

Ate, regarding your patch, didn't you receive your Apache account yet?
If so, no need to send patches, unless you just want us to test it out.

I prefer that we resolve the issues above before applying Ate's solution to JS2-56 (this issue)

View this comment:

View the issue:

Here is an overview of the issue:
        Key: JS2-56
    Summary: Objects Fail to Create with Tomcat Classloaders and cross context
       Type: Task

     Status: Open
   Priority: Major

    Project: Jetspeed 2
             Components Core
   Fix Fors:

   Assignee: David Sean Taylor
   Reporter: David Sean Taylor

    Created: Tue, 25 May 2004 9:35 PM
    Updated: Fri, 28 May 2004 10:45 AM
Environment: Tomcat 4 and 5

J2 uses a cross-context class loader to share objects created in the jetspeed context with
other portlet application contexts. This works fine when objects have already been instantiated
in the jetspeed context. 

J2 infuses a common servlet into every portlet application that is deployed into a Tomcat
application server via the J2 portal's PAM (Portlet Application Manager). The code that runs
in this servlet is placed in Tomcat's shared/lib directory so that both Jetspeed common servlet
and the Jetspeed portal can share objects. 

The problems I am seeing with this approach are rooting in the creation of new objects. For
example, if a portlet application, such as the HW_App, has a portlet UserInfo, that requires
creation of preference objects. Preference objects by OJB. Looking at the code used by the
ojb object broker


you see object creation taking place as:

  result = constructor.newInstance(NO_ARGS);

And this code fails, class not found exception. It fails to find the object to be created,
such as a NodeImpl, which is deployed in the Prefs jar, normally stored under jetspeed's WEB-INF/lib
directory. This tells me that the classloader being used by the code above is not the same
as the cross-context classloader in Tomcat...or...the Tomcat cross-context class loader is
not designed to handle this kind of object construction.

I think we have several directions we can take for a solution
One experiment I tried with Tomcat 4.1.30, was:

1. move every jar out of WEB-INF/lib into shared/lib
2. delete all classes under WEB-INF/classes
3. copy jetspeed-2.0-a1.jar into shared/lib
4. move the JDBC driver into Tomcat's system directory or into the classpath

This seemed to work, although for some reason I could not login to the LoginPortlet tonight.
Not sure if its related. The solution is simple here: move everything down into shared/lib.

A second solution would be to replace Tomcat's cross-context class loader with our own.
Although I have not found a 'pluggable' way to do this.

A third solution would be to modify the classloader in the Jetspeed common servlet.
I have started some testing in this area without any success (yet):


see the infuseClasspath method

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