(Noticed it on second read) BTW, getClassLoader() _may_ return null for bootstrap class loader. AFAIR, IBM's VME provides Java class loader instance for bootstrap class loader. The other thing is that for all classes that belongs to class library a call to getClassLoader must return the same value (either null or real class loader instance). If it's an instance it may then delegate to corresponding bundle loaders based on package or class name, but the implementation have to make sure that a call to getClassLoader returns this top level instance but not the bundle loader to which real loading was delegated.
Pavel. On Tue, Jun 2, 2009 at 12:27 PM, Pavel Pervov <[email protected]> wrote: > Carlos, > > AFAIU, the idea was to move harmony class library to use OSGi style > (per-bundle) loading. That's why it is necessary to stuff it into > DRLVM. > > WBR, > Pavel. > > 2009/6/2 Carlos Torrão <[email protected]>: >> The eclipse equinox implements the OSGi Framework only in Java, since the >> file comes in .jar file and can run in every JVM. >> >> I tried to start the OSGi implementation of equinox with Harmony and it >> worked fine. >> >> java -jar org.eclipse.osgi_3.4.0.v20080605-1900 -console >> >> Don't understand why do you need to change this JVM to implement OSGi... >> >> Best regards, >> Carlos Torrão >> >> >> 2009/5/20 Pavel Pervov <[email protected]> >> >>> Sure. I've posted from mobile, and my multitap betrayed me. Thanks, Mark. >>> >>> 2009/5/20, Mark Hindess <[email protected]>: >>> > >>> > In message <[email protected] >>> >, >>> > Pavel Pervov writes: >>> >> >>> >> Please, read this nice presentation [1] on osgi vs classic class >>> loading. >>> >> [1] >>> >> >>> http://www.martinliqert.com/events/WJAX2008-ClassloadingTypeVisibilityOSGi.pdf >>> > >>> > I assume you mean: >>> > >>> > >>> > >>> http://www.martinlippert.org/events/WJAX2008-ClassloadingTypeVisibilityOSGi.pdf >>> > >>> > -Mark. >>> > >>> >> 2009/5/19, tian galaxy <[email protected]>: >>> >> > XiaoFeng , Mark >>> >> > Thanks for your help ,very valuable to me. >>> >> > I think I need to research more on this .Much more complex than I >>> >> > thought >>> >> > previously. >>> >> > >>> >> > >>> >> > Regard >>> >> > Tian >>> >> > >>> >> > 2009/5/19 Xiao-Feng Li <[email protected]> >>> >> > >>> >> >> On Tue, May 19, 2009 at 6:41 PM, Mark Hindess >>> >> >> <[email protected]> wrote: >>> >> >> > >>> >> >> > In message >>> >> >> > <[email protected]>, >>> >> >> tian >>> >> >> > galaxy writes: >>> >> >> >> >>> >> >> >> 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 <[email protected]> >>> >> >> >> > >>> >> >> >> > In message < >>> >> >> [email protected]>, >>> >> >> >> > 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? >>> >> >> > >>> >> >> > It isn't necessary but I think it is useful to use a separate >>> >> >> > classloader for the OSGi framework so that we can isolate the >>> classes >>> >> >> > use by the VM's OSGi framework and avoid polluting the namespace. >>> >> >> > >>> >> >> >> Do you mean the bootstrap class loader should delegate the loading >>> >> >> >> to >>> >> >> >> the 'unique class loader '? >>> >> >> > >>> >> >> > Yes. >>> >> >> > >>> >> >> >> > and the system classes (with a "temporary" classloader). >>> >> >> >> >>> >> >> >> Again ,the relation between temporary and bootstrap classloder? >>> And >>> >> >> >> why temporary ? >>> >> >> > >>> >> >> > Temporary because until the OSGi framework is up you wont know >>> which >>> >> >> > bundle the classes belong to and thus wont know which bundle >>> >> >> > classloader >>> >> >> > the classes should belong to. Alternatively, I suppose you could >>> >> >> > implement minimal support for reading OSGi headers from manifests >>> >> >> > in the VM so that you could assign classes to what would become a >>> >> >> > bundle >>> >> >> > classloader when the framework is up. >>> >> >> > >>> >> >> > -Mark. >>> >> >> >>> >> >> >>> >> >> This makes sense to me. The VM simply grabs in all the stuff "as >>> >> >> usual" including the OSGi framework, then sort them out according to >>> >> >> the bundles' definitions. >>> >> >> >>> >> >> It could be VM-neutral, because it is the VM's own business to take >>> >> >> care of its loaded classes. A callback interface OSGI_ready() can >>> >> >> inform the VM to tidy up the classes loaded for OSGi (or before it is >>> >> >> ready). >>> >> >> >>> >> >> Thanks, >>> >> >> xiaofeng >>> >> >> >>> >> >> >>> >> >> >> > 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 <[email protected]> >>> >> >> >> > > >>> >> >> >> > > > 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 <[email protected]>: >>> >> >> >> > > > > 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 <[email protected]> >>> >> >> >> > > > > >>> >> >> >> > > > >> Short answer is "no". You'll have to implement osgi >>> loading >>> >> >> model >>> >> >> >> > > > >> inside bootstrap classloader. Is it too complex? >>> >> >> >> > > > >> >>> >> >> >> > > > >> 2009/5/18, tian galaxy <[email protected]>: >>> >> >> >> > > > >> > 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 <[email protected]> >>> >> >> >> > > > >> > >>> >> >> >> > > > >> >> 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 <[email protected]>: >>> >> >> >> > > > >> >> > 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? >>> >> >> > >>> >> >> > >>> >> >> > >>> >> >> >>> >> >> >>> >> >> >>> >> >> -- >>> >> >> http://people.apache.org/~xli <http://people.apache.org/%7Exli> >>> >> >> >>> >> > >>> >> > >>> >> > >>> >> > -- >>> >> > Regards >>> >> > Michael Tian >>> >> > >>> >> >>> > >>> > >>> > >>> >> >
