On 18 Sep, David Jencks wrote:
> On 2002.09.18 09:33:40 -0400 Peter Antman wrote:
>> Hi, i am sorry if I have slept under a stone the last 6 month or so, but
>> I have to say I find the new classloader aproach somewhat frustrating
>> (if I am not wrong in what follows).
>> 
>> At least in 3.0 the following scenario (among others) would apply:
>> 
>> Say we wanted to integrate two system services (as mbeans). 
>> 
>> a) Both uses a common library, but of differents versions.
>> b) Both uses a lib that also JBoss uses, but of later version.
>> 
>> What happens in this case with the current CL aproach, well.
>> 
>> b) is impossible if you do not change the lib used by JBoss (speek about
>> cost of integration to verify that that works).
>> 
>> a) is stocastic. The Mbean getting deployed first will rule wich classes
>> are loaded and cached globaly.
>> 
>> As far as I have found out the only type that do not have this problem
>> is *.ear when used with the Heir...Repository. But no other packages
>> types has this option.
>> 
>> Would it not be good to, either
>> 1) Have the same optional Heir..Rep for at least SAR modules, so they
>>  can load local classes that are different from global ones.
> 
> I set up the ulr stuff in 3.2 so it would be really easy to extend to other
> module types.  Go ahead if you would like it for sars.  In 3.0 branch it is
> a little harder.  I didn't feel really pressed to do this since you can put
> any kind of package you want in an .ear and get the same effect.

Ok. Just seams a little waird to deploy server components inside emtry
sars. But ok, that is maybe the way to go.

I will starts looking into 3.2 when I have finalized som more of my
stuff. ulr - what is that? ;-)
> 
>> 
>> or
>> 2) Change the loading algoritms so its looks something like this:
>> 
>> - Check cache connected to classloader
>> - Check local classloader (cache localy, and globaly if its not there)
>> - Check global cache
>> - Check global repository
>> 
>> The later does, however, not fully solve the problem with dependant jars
>> embedded in a sar, since - if I understand it correctly - they are
>> loaded as equal sitizens of the global repository. Here I guess only the
>> HeirarchicalLoaderRepository2 is a solution (but with that aproach
>> classes will not become available globaly, only in the Heir...Rep).
> 
> I think this is apt to cause more problems than it solves.  To solve the "I
> want a different version of a lib used internally by jboss" you'd have to
> find a way of making that part of jboss use a non-default hier.loader
> repository.  

?

I guess it will work out of the box with the Heir..Rep, since classes
are loaded locally firts.

>This is presumably possible but sounds like a big hassle, in
> particular to maintain and test continually.  In this case, didn't we have
> the same problem in 2.4? 

Yea I know, which is part of my disapointment. I reallt thought that hod
deploy of server components would solve the hazzle of beeing forced to
have all your custom libs in lib/ext and overwriting jboss system libs
and restarting the server. In the 2.4 line you do not just install
JBoss, you have to install your application with a specific JBoss ;-).

> Which library are you having problems with in
> particular?

In this case its concurrent.jar, but I have not yet checked which
version is which. I see it mostly as a symptom.

Thanks

//Peter
> 
> thanks
> david jencks
> 
>> 
>> 
>> Or have I gone completely nuts?
>> 
>> //Peter
>> -- 
>> ------------------------------------------------------------
>> Peter Antman Chief Systems Architect, Business Development
>> Technology in Media, Box 34105 100 26 Stockholm
>> WWW: http://www.tim.se       WWW: http://www.backsource.org
>> Email: [EMAIL PROTECTED]     
>> Phone: +46-(0)8-506 381 11 Mobile: 070-675 3942 
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-- 
------------------------------------------------------------
Peter Antman    Chief Systems Architect, Business Development
Technology in Media, Box 34105 100 26 Stockholm
WWW: http://www.tim.se  WWW: http://www.backsource.org
Email: [EMAIL PROTECTED]        
Phone: +46-(0)8-506 381 11 Mobile: 070-675 3942 
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