On Wed, 31 Jul 2002, Adrian Prezioso wrote:
> Date: Wed, 31 Jul 2002 11:36:45 -0700 (PDT)
> From: Adrian Prezioso <[EMAIL PROTECTED]>
> Reply-To: Tomcat Developers List <[EMAIL PROTECTED]>
> To: Tomcat Developers List <[EMAIL PROTECTED]>
> Subject: Re: how to do auto update/reload of a class?
>
> Craig,
> who controls loading and reloading jasper class
> loaders? and how is it being managed? I'm also
> working on a project where I need to auto-reload Java
> classes at runtime. If you could point me to any kind
> of documentation, that'd be greatly appreciated.
>
The source code for JspServlet and friends is the best bet for figuring
this out.
> thanks,
> Adrian
Craig
>
> --- "Craig R. McClanahan" <[EMAIL PROTECTED]> wrote:
> >
> >
> > On Wed, 31 Jul 2002, Babu Wisor wrote:
> >
> > > Date: Wed, 31 Jul 2002 10:15:08 -0700 (PDT)
> > > From: Babu Wisor <[EMAIL PROTECTED]>
> > > Reply-To: Tomcat Developers List
> > <[EMAIL PROTECTED]>
> > > To: Tomcat Developers List
> > <[EMAIL PROTECTED]>
> > > Cc: [EMAIL PROTECTED]
> > > Subject: Re: how to do auto update/reload of a
> > class?
> > >
> > > Hi All,
> > > Does anyone have any thoughts as to how to
> > auto
> > > re-load the classes, which have been loaded into
> > JVM
> > > using Custom Class loader? I tried writing custom
> > > class loader and loaded all the classes, but don't
> > > know how to re-load the same class, if it has been
> > > modified (re-compiled) without shutting down JVM,
> > > similar to JSP engine, where if we put updated JSP
> > > file, it picks up the new file.
> > >
> >
> > Jasper does this by creating a class loader for each
> > page, and throwing
> > away the class loader when the page is recompiled.
> > The JVM doesn't let
> > you do things any other way.
> >
> > > Note: I learnt that, we need to recreate new class
> > > loader and load all the classes again, but don't
> > know
> > > exactly how to apply that technique in the system.
> > Any
> > > help is greatly appreciated.
> > >
> >
> > My personal advice, after living through (barely :-)
> > getting a class
> > loader that would reload a webapp to work, is to
> > abandon this approach
> > unless you are just doing it for fun and learning
> > how class loading works.
> > You are going to find that the fundamental
> > architecture of Java isn't
> > really oriented towards incremental replacement of
> > classes (although there
> > is a little bit better support in 1.4).
> >
> > > Thank you,
> > > Babu
> >
> > Craig
> >
> > > --- Ian Darwin <[EMAIL PROTECTED]> wrote:
> > > > On July 28, 2002 10:32 pm, you wrote:
> > > > > Does anyone know, how to do auto update of
> > > > classes
> > > > > into the JVM? I
> > > > > tried to write my own custom class loader, and
> > > > loaded
> > > > > all the classes
> > > > > through it, however if I put new updated
> > class, it
> > > > > won't reload the
> > > > > class again. Have anyone tried this before?
> > Help
> > > > is
> > > > > very much
> > > > > appreciated.
> > > >
> > > > This better asked on an advanced-java list; not
> > > > tomcat specific.
> > > >
> > > > For all the cleverness of Java's dynamic loading
> > > > mechanism (ClassLoader,
> > > > Class.forName, newInstance(), etc.), there is no
> > > > published API for unloading or reloading.
> > > > They just didn't think of it in time, perhaps.
> > > >
> > > > What I think Tomcat and others do is basically
> > to
> > > > manage the class loader for each Context
> > > > (which has to be separate from the CL for each
> > other
> > > > Context for configuration
> > > > and security reasons anyway) in such a way that
> > you
> > > > can delete
> > > > it (un-reference it) and assign a new one and
> > reload
> > > > the classes
> > > > for the given Context.
> > > >
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> > >
> > >
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>
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