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From tian galaxy <harmonymail...@gmail.com>
Subject Re: Question about the boot and classloading
Date Tue, 19 May 2009 08:47:09 GMT
Hindess .Thanks for the help ! I realized that this far more complex than I
thought before .
So I think I need a deeper look into both osgi and harmony .
Here are several things I don't qiute understand and I noted them below.May
be it's because I am not quite familiar with the low level , classloading
details .
thanks!

2009/5/19 Mark Hindess <mark.hindess@googlemail.com>

>
> In message <dff214c70905180610w407e3bd4h5baa319729c1fc55@mail.gmail.com>,
> tian
> galaxy writes:
> >
> > OK ,thanks .Seems the minimal class set has been defined by the osgi.
>
> Not sure how this helps though.  The OSGi Minimum Execution Environment
> says what is theoretically the minimum required to run OSGi.  What we
> need to concern ourselves with is the *practical* minimum and that
> really depends on our implementation details.
>
> I don't think that we should implement OSGi in the VM.  Instead the
> existing bootstrap classloader should load the OSGi framework (with
> a unique classloader)

If we load the osgi with the bootstrap class loader , why comes a unique
class loader?
Do you mean the bootstrap class loader should delegate the loading to the
'unique class loader '?

and the system classes (with a "temporary"
> classloader).

Again ,the relation between temporary and bootstrap classloder ?And why
 temporary ?

>  Once the OSGi framework is configured the system classes
> need to be moved to the correct classloader for the OSGi bundle to which
> they belong.
>
> This means that during the initial starting-OSGi-framework phase
> the OSGi bundle import/exports will not be enforced

but, other than
> implementing OSGi in the VM, I don't see how to avoid this.


>
> The multiplicity of bootstrap classloaders still needs to be hidden
> since the API demands that getClassLoader should return null for the
> bootstrap classloader(s).
>
> The biggest problem is probably how to implement this as VM-independent
> API such that a VM wanting to implement OSGi had to provide only a
> minimal C/Java interface in order to gain OSGi support.
>
> Regards,
>  Mark.
>
> > I will look more closely on this problems and let you know if there some
> > progresses made.
> > Thanks  a  lot !
>
> > 2009/5/18 Pavel Pervov <pmcfirst@gmail.com>
> >
> > > I do not know osgi model in detail, but what minimal set of classes is
> > > needed to start osgi model itself? Then we could delegate to "system"
> > > bundle loader from bootstrap classloader.
> > >
> > > 2009/5/18, tian galaxy <harmonymail.ty@gmail.com>:
> > > > Yes , implement osgi loading model in there is too complex.
> > > >
> > > > We know some modules are more important than others , performing some
> > > > fundamental , basic functions .
> > > > Is it possible to only load these more" basic " modules with
> bootstrap
> > > class
> > > > loader and make the other modules work the osgi bundle?
> > > > Actually I don't quite understand why system classes could only be
> loaded
> > > by
> > > > bootstrap class loader?I noticed that there are some safety concerns
> > > > ,is there any reasons other than that?
> > > > Thanks !
> > > >
> > > >
> > > > 2009/5/18 Pavel Pervov <pmcfirst@gmail.com>
> > > >
> > > >> Short answer is "no". You'll have to implement osgi loading model
> > > >> inside bootstrap classloader. Is it too complex?
> > > >>
> > > >> 2009/5/18, tian galaxy <harmonymail.ty@gmail.com>:
> > > >> > Hi Pavel.
> > > >> >
> > > >> > Thanks.
> > > >> > Yes ,that's right .My question is whether there is a way to load
> the
> > > >> system
> > > >> > class by class loader other than the  bootstrap class loader
?
> > > >> > If we could load the system class by different loaders other
than
> the
> > > >> > bootstrap class loader then there is a chance to make the harmony
> > > >> > runtime
> > > >> to
> > > >> > be osgi-ed.
> > > >> > I trying to work on this problem . Do you have any suggestions
?
> > > >> >
> > > >> >
> > > >> > 2009/5/18 Pavel Pervov <pmcfirst@gmail.com>
> > > >> >
> > > >> >> Tian,
> > > >> >> System classes are all loaded with bootstrap classloader.
It is
> > > >> >> written in C++ and is located in
> > > >> >> working_vm/vm/vmcore/src/class_support/classloader.cpp
> > > >> >>
> > > >> >> 2009/5/17, tian galaxy <harmonymail.ty@gmail.com>:
> > > >> >> > Hi all
> > > >> >> > I have a question about the classloading in the drlvm.
> > > >> >> >
> > > >> >> > I know that there are kernel library inside the drlvm
such as
> > > >> >> > java.lang.classloader, which enclose the the systemclassloader.
> And
> > > >> this
> > > >> >> > class is loaded and used in the process of creating
VM .
> > > >> >> > While the systemclassloader is a subtype of urlclassloader
> which is
> > > >> >> > in
> > > >> >> the
> > > >> >> > "luni" module.So does the JNI_CreateJavaVM
> > > >> >> > also load the urlclassloader in the boot procedure of
vm ?(I
> failed
> > > >> >> > to
> > > >> >> > search related code in the source code of drlvm).
> > > >> >> > If so , when ?Before or after the jni available ?
> > > >> >> > Since I am trying to implement the osgi on harmony and
the osgi
> > > works
> > > >> >> with
> > > >> >> > bundles (modules) , I think I need to know the procedure
of
> booting
> > > >> and
> > > >> >> > loading of class from different modules at the start
up time.
> > > >> >> > Any clue about this ?Thanks
> > > >> >> >
> > > >> >> > plus,do we have the source code of java.exe ?Where?
> > > >> >> >
> > > >> >> > --
> > > >> >> > Regards
> > > >> >> > Michael Tian
> > > >> >> >
> > > >> >>
> > > >> >
> > > >> >
> > > >> >
> > > >> > --
> > > >> > Regards
> > > >> > Michael Tian
> > > >> >
> > > >>
> > > >
> > > >
> > > >
> > > > --
> > > > Regards
> > > > Michael Tian
> > > >
> > >
> >
> >
> >
> > --
> > Regards
> > Michael Tian
> >
> > --0016363ba4b87ec6cc046a2f8544--
> >
>
>
>


-- 
Regards
Michael Tian

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