David Le Strat wrote:
I have no objections, only not much hope they would wanna fix this themselves (any time soon).Ate,
I think we should cross post your comments on the OJB
and Jetspeed development lists and initiate a
discussion around this.
I also think we should do the same regarding the Tomcat JAASRealm issue.
What do you think?
The comments in their current form are also too J2 specific to have much effect. I think they must be rewritten as proper questions targeted at each list.
I can do that but actually don't feel like it right now (I'm swapped with other issues myself which got delayed already too much because of all this).
I think what might be more effective is a direct discussion with some of their lead developers. Maybe I've overlooked some solutions they might see. A few weeks back David Taylor invited Brian McCallister to discuss our problems with OJB. Inviting him back to discuss the current issue might be an idea? Also, if someone knows Remy Maucherat from Tomcat maybe he could be invited to discuss our problems with the JAASRealm. I don't have the contacts yet ;-) to do so but maybe David Sean Taylor, you or someone else?
Regards,
Ate
Regards,
David.
--- [EMAIL PROTECTED] wrote:
The following comment has been added to this issue:
Author: Ate Douma Created: Fri, 28 May 2004 5:26 AM Body: I think I have found solution which I think might be the easiest way to go.
There is one big consequence that I don't like but it applies to any other valid solution we have come up with so far (except patching the Tomcat ClassLoaders or OJB itself which I personally don't see as acceptable options). I will come back to this consequence below.
What I did was moving all the classes which OJB might instantiate dynamically (using the currentThread contextClassLoader) into commons. This involves *all* the om classes, a few ojb util classes like the FieldConversion implementations, and the OJB jar itself.
I also needed to refactor the StoreablePortletDefinitionDelegate which was dependent on PersistencyStore. I solved that by creating a new interface (PortletDefinitionStoreDelegate) which defines handling the store functionality and a implementation class of which a StoreablePortletDefinitionDelegate gets supplied in its constructor.
Furthermore, I moved registry o.a.j.components.portletentity.PortletEntityImpl, which really is an om class, to a new commons package o.a.j.om.common.entity.impl. I guess this one was overlooked in abstracting the om classes.
Thats all. All the current classloader issues are solved by this.
Because I moved all these om packages to commons we will lose the cvs history on all these files though. Thats bad, but the price of still using cvs.
There is one more big consequence though which should be considered before this is applied (I will attach a patch file after this comment). Moving the ojb jar to tomcat shared/lib means that external portlet apps which also want to use ojb really are forced to use the version supplied by J2.
In theory, a web-app can supply its own version of
ojb in its WEB-INF/lib folder and it *will* override
the version in shared/lib (servlet api spec
compliance).
But, because J2 also uses OJB, om objects loaded
through J2 will have a different classloader as the
ones loaded through a portlet app.
Thus, this locks portlet developers who want to use
OJB (but, who would, honestly?) into the version
supplied by J2 (and are not even allowed to put the
same version in their WEB-INF/lib folder).
Currently, I don't see how this can be prevented
though. If we don't want to put OJB into shared/lib
we will have to hack the Tomcat classloaders, or
hack OJB itself for not using the ContextClassLoader
anymore. I think the OJB team made a wrong decision how to
implement the dynamic classloading. In its current
form OJB cannot be used by any web application using
cross-context functionality without the same
consequence. Maybe they can be convinced to change
this but I don't see that happen overnight and we
need a solution now...
If we are going for this solution then we can go
full speed ahead again.
But we must be very careful not (re)introducing these kind of problems. Maybe not only OJB causes these kind of problems. The rules to prevent this are simple: 1) Put all classes which might get dynamically created through the ContextClassLoader by a external web app into shared/lib. 2) If one of those classes need an object reference only available to J2 itself, Dependency Injection is required based on interfaces in shared/lib (like I did with StoreablePortletDefinitionDelegate).
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View this comment:
http://issues.apache.org/jira/browse/JS2-56?page=comments#action_35764
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View the issue: http://issues.apache.org/jira/browse/JS2-56
Here is an overview of the issue:
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Key: JS2-56 Summary: Objects Fail to Create with Tomcat Classloaders and cross context Type: Task
Status: Open Priority: Major
Project: Jetspeed 2
Components: Components Core
Fix Fors:
2.0-dev/cvs
Versions:
2.0-a1
Assignee: David Sean Taylor Reporter: David Sean Taylor
Created: Tue, 25 May 2004 9:35 PM Updated: Fri, 28 May 2004 5:26 AM Environment: Tomcat 4 and 5
Description:
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
http://cvs.apache.org/viewcvs.cgi/db-ojb/src/java/org/apache/ojb/broker/util/ConstructorHelper.java
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):
http://cvs.apache.org/viewcvs.cgi/jakarta-jetspeed-2/commons/src/java/org/apache/jetspeed/container/JetspeedContainerServlet.java
see the infuseClasspath method
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