On 2002.09.18 10:28:19 -0400 Peter Antman wrote:
> 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 agree, but at least there is some way to do it.

> 
> I will starts looking into 3.2 when I have finalized som more of my
> stuff. ulr - what is that? ;-)

unified loader repository. I should have said loader repository.
> > 
> >> 
> >> 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.

(I think) the jars in lib rather than server/[conf]/lib are not going to be
versionable since they are used in jboss startup to set up the versioning
mechanism.  Stuff in server/[conf]/lib should be versionable by deploying
it in a .sar, although you may have problems with deployment order.

I wasn't aware that there had been any changes in concurrent.jar for
years... can you provide details, we should probably upgrade.

thanks
david jencks
> 
> 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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