RE: Business Objects vs Data Objects [was Re: JXTemplates-what' s in a name?]

[Ralph Goers <Ra...@digitalinsight.com>]

If you review the developers list you will find that the Cocoon developers
would very much like to implement something like what you are suggesting by
being able to dynamically deploy/redeploy/undeploy blocks.  However, there
are significant issues that make this a non-trivial task.

Unfortunately, because Java class loaders don't have versioning support
built in you can't just simply upgrade jars in a running system on the fly.
You are making the assumption that upgrading a jar from one version to the
next will always be binary compatible. This is not always the case. To make
things worse, some of the jars have to exist in the endorsed overrides
directory which requires a restart of your web container to change them -
not just a redeployment.

Ralph

-----Original Message-----
From: Leon Widdershoven [mailto:qaz@dds.nl] 
Sent: Sunday, May 09, 2004 10:48 AM
To: users@cocoon.apache.org
Subject: Re: Business Objects vs Data Objects [was Re: JXTemplates-what' sin
a name?]

I have no clue. Is there no application server which can deal with time 
stamped libraries? The
way dynamic generation in xsp works (not the implementation of which I 
know next to nothing,
but the fact that your classes are always up to date) is a very strong 
convenience feature.

If that could be extended to the application jar's (e.g. 
cocoon/WB-INF/lib, not tomcat/libs) in the
way the sitemap has a check-reload that would make it so much easier to 
develop web applications,
especially since development seems to shift away from xsp to flowscript, 
with the flowscript
acting as a controller and not containing the business logic.

Leon


---------------------------------------------------------------------
To unsubscribe, e-mail: users-unsubscribe@cocoon.apache.org
For additional commands, e-mail: users-help@cocoon.apache.org

Re: Business Objects vs Data Objects [was Re: JXTemplates-what' s in a name?]

[Leon Widdershoven <qa...@dds.nl>]

I know. And I also know that such a feat is not easy at all, which is at
least partially caused by the infamous jar hell. You'd have thought that
Solaris/unix people would not make the windows mistake. Alas.

I have never really understood what's special about endorsed (it overrides
the default class path?) but that application-global (with the servlet
container the application) jars require a restart is of course to be taken
for granted. It's just that I'd like to see web-application specific libraries
(the ones I use for the applications running "in" cocoon running in the
servlet container) could be reloaded. I think such a feature would prove
a strong impulse to flowscript based application development.

May the person responsible for not adding versioning to jars have
many itches daily,

Leon

Ralph Goers wrote:
> If you review the developers list you will find that the Cocoon developers
> would very much like to implement something like what you are suggesting by
> being able to dynamically deploy/redeploy/undeploy blocks.  However, there
> are significant issues that make this a non-trivial task.
> 
> Unfortunately, because Java class loaders don't have versioning support
> built in you can't just simply upgrade jars in a running system on the fly.
> You are making the assumption that upgrading a jar from one version to the
> next will always be binary compatible. This is not always the case. To make
> things worse, some of the jars have to exist in the endorsed overrides
> directory which requires a restart of your web container to change them -
> not just a redeployment.
> 
> Ralph
> 
> -----Original Message-----
> From: Leon Widdershoven [mailto:qaz@dds.nl] 
> Sent: Sunday, May 09, 2004 10:48 AM
> To: users@cocoon.apache.org
> Subject: Re: Business Objects vs Data Objects [was Re: JXTemplates-what' sin
> a name?]
> 
> I have no clue. Is there no application server which can deal with time 
> stamped libraries? The
> way dynamic generation in xsp works (not the implementation of which I 
> know next to nothing,
> but the fact that your classes are always up to date) is a very strong 
> convenience feature.
> 
> If that could be extended to the application jar's (e.g. 
> cocoon/WB-INF/lib, not tomcat/libs) in the
> way the sitemap has a check-reload that would make it so much easier to 
> develop web applications,
> especially since development seems to shift away from xsp to flowscript, 
> with the flowscript
> acting as a controller and not containing the business logic.
> 
> Leon
> 
> 
> ---------------------------------------------------------------------
> To unsubscribe, e-mail: users-unsubscribe@cocoon.apache.org
> For additional commands, e-mail: users-help@cocoon.apache.org
> 

---------------------------------------------------------------------
To unsubscribe, e-mail: users-unsubscribe@cocoon.apache.org
For additional commands, e-mail: users-help@cocoon.apache.org