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From galaxy <tian.gal...@gmail.com>
Subject Re: The OSGi-Harmony Runtime
Date Sun, 16 Aug 2009 11:33:28 GMT
Hi Mingjian,
Maybe I am not clear enough in the introduction :)

The main theme of the work is to let some of the modules to be governed by
the OSGi framework and then
make the whole " jre + felix + osgi bundles (modules) " a  working runtime
of java ,could run the java applications
in the normal way .The transparency from the user side I think.


2009/8/16 Jin Mingjian <jin.phd@gmail.com>

> galaxy, still good work:) I am not the man to evaluate your work:)
>
> your work = mini Harmony jre + Felix?
>
> such as one question:
> how your runtime works?

I think the best outcome is that it can work the same as a normal JRE from
the user's point of view

> Does it support mixed jar usage?(seem your "For B"?
> A bundle jar can be seen as a bundle or a pure application jar depended on
> the context. there are some interesting things happened here)

the classloading mechanism  I listed in the review determines that classes
in the osgi
bundle will come before app , so if the same jar files acts as a bundle and
at the same time a app jar , the app jar file is useless I think.

>
>
>
>
>
> 2009/8/16 galaxy <tian.galaxy@gmail.com>
>
> > I'm sorry but I think you should have missed some thing in the review
> .the
> > OSGi framework I use is Felix, and all the security and dynamic comes
> from
> > it and built in with it,
> > if you want to find the osgi-ed security and dynamic
> > does this answer your question ?
> >
> > 2009/8/16 Jin Mingjian <jin.phd@gmail.com>
> >
> > > interesting. I'd like to mainly examine the dynamic and security of
> > > your OSGi-Harmony runtime when the codes is ready.
> > >
> > > 2009/8/16 Xiao-Feng Li <xiaofeng.li@gmail.com>
> > >
> > > > Good work! How much is the size of the minimum OSGi-ed JRE?
> > > >
> > > > Thanks,
> > > > xiaofeng
> > > >
> > > > On Sun, Aug 16, 2009 at 3:22 PM, galaxy<tian.galaxy@gmail.com>
> wrote:
> > > > > Hi  all
> > > > >    Now the code for OSGi-ed Runtime of Harmony is almost complete
,
> > I'd
> > > > > like to give a review of
> > > > > the work so far.The code and usage will be uploaded together soon
> > > > >
> > > > > Introduction To OSGi-ed JRE
> > > > >
> > > > >
> > > > >
> > > > > 1 : The main purpose
> > > > >
> > > > > OSGi has become one of the best ways to govern the jar files in a
> > > number
> > > > of
> > > > > applications Such as the power it exhibits in eclipse .And as we
> all
> > > know
> > > > > ,the Harmony runtime is a modularized one and each module , with
> its
> > > > > manifest file , is just like one bundle in the OSGi framework .So
> we
> > > are
> > > > > think of governing the modules in Harmony runtime in a OSGi-ed way.
> > > > >
> > > > >
> > > > >
> > > > > 2 : Ways to meet the main purpose
> > > > >
> > > > >       Naturally, there are two ways to meet this purpose:
> > > > >
> > > > > A  Implementing the OSGi framework in VM in C/C++ to govern all the
> > > java
> > > > > modules
> > > > >
> > > > > B  Using one of the OSGi-ed framework implemented in java to
> > > implemented
> > > > a
> > > > > half OSGi-ed JRE.
> > > > >
> > > > >       Finally I picked the plan B with the well known OSGi
> framework
> > > > :Felix
> > > > > .And the reasons are as follows
> > > > >
> > > > > First : Implementing a OSGi-ed framework from scratch in c/c++ in
> the
> > > vm
> > > > is
> > > > > difficult and time-consuming .
> > > > >
> > > > > Second : Plan A suffers from the facts that implementations differs
> > > huge
> > > > > from VM to VM .Plan B won’t have this kind of problem as long as
> the
> > > > modules
> > > > > comply with the OSGi specifications and we have a adapted java.exe
> ,
> > > the
> > > > > rest is nearly the same.
> > > > >
> > > > > Third : Beside the framework ,each OSGi implementation has a lot
of
> > > > add-ons
> > > > > .This will facilitate future development of new features and
> > utilities
> > > > .For
> > > > > example : the could use the bundle fileinstall to install all the
> jar
> > > > files
> > > > > lies in a folder ,very helpful in certain circumstances.This could
> be
> > > > done
> > > > > rapidly if we choose plan B .
> > > > >
> > > > >
> > > > >
> > > > > 3 : Problems and fixes
> > > > >
> > > > > The difficulties ,or the main tasks ,of this project are as follows
> > > > >
> > > > > A     Find the minimum working environment of OSGi-framework and
> > modify
> > > > the
> > > > > rest modules in Harmony ,mainly the manifest file ,to resolve the
> > > > coupling
> > > > >
> > > > > B     Modify the classloading mechanism and booting of the jre to
> be
> > > able
> > > > > run normal java applications
> > > > >
> > > > > And the fixes are
> > > > >
> > > > > For A:
> > > > >
> > > > > Harmony is a modularized runtime .So determine the minimum working
> > > > > environment is no more than choose the right module to stay with
> the
> > VM
> > > > > .However ,although the coupling is little , it does exist . So a
> > > > > modification of the module is necessary ,mainly the manifest file
> > .And
> > > as
> > > > I
> > > > > want  to remain the original structure of Harmony as largely as
> > > possible
> > > > > ,more contents (classes ) will be included in the minimum
> environment
> > > > other
> > > > > than splitting the modules apart .The final jre include the
> following
> > > > > component :
> > > > >
> > > > >
> > > > >
> > > > > luni.jar
> > > > >
> > > > > annotation.jar
> > > > >
> > > > > security.jar
> > > > >
> > > > > math.jar
> > > > >
> > > > > text.jar
> > > > >
> > > > > regex.jar
> > > > >
> > > > > noi_char.jar
> > > > >
> > > > > nio.jar
> > > > >
> > > > > logging.jar
> > > > >
> > > > > concurrent.jar
> > > > >
> > > > > archive.jar
> > > > >
> > > > > the ICU4J folder.
> > > > >
> > > > >
> > > > >
> > > > > The remaining jars are governed by the OSGi framework to handle.
> One
> > > more
> > > > > thing to mention is the two classes
> > > > >
> > ,”java.beans.PropertyChangelinstener”,”java.beans.PropertyChangeEvent”
> > > > has
> > > > > to be moved out of beans.jar .This is because of the coupling of
> > > > beans.jar
> > > > > with other modules in the minimum runtime .Well the good thing is
> > these
> > > > two
> > > > > classes havn’t imports any other classes in the modules governed
by
> > the
> > > > OSGi
> > > > > framework .I think we could include them in any modules lie in the
> > > > minimum
> > > > > runtime as long as the VM could find them .
> > > > >
> > > > >
> > > > >
> > > > > For B:
> > > > >
> > > > > I added one extra sphere between the VM and the main class to run
> > > > > .org.apache.osgi.FelixStarter. , the following is done in this
> class
> > > > >
> > > > > First: Loading the configurations and Start Felix ,the OSGi
> framework
> > > we
> > > > use
> > > > >
> > > > > Second: Initializing the class org.apache.osgi.OsgiClassLoader
> ,this
> > > > class
> > > > > will load the main class and subsequently all the classes used in
> the
> > > > main
> > > > > class
> > > > >
> > > > > Third: Transfer the arguments to the “real “ main class ,invoke
the
> > > main
> > > > > method .
> > > > >
> > > > >
> > > > >
> > > > > The sequence of class loading is as follows :
> > > > >
> > > > >
> > > > >
> > > > > First : Check the class name to determine whether it should be
> loaded
> > > by
> > > > the
> > > > > parent class loader .This work is done by specifying the
> > > > > “org.osgi.framework.bootdelegation” property to include all the
> > package
> > > > > names in the modules stays in the VM .
> > > > >
> > > > > Second : load the classes in the bundle governed by the framework
> .I
> > > will
> > > > > examine each bundle's export and import property to search for the
> > > class
> > > > > name ;
> > > > >
> > > > > Third : the classes in the application’s class path .
> > > > >
> > > > > Finally : we could not find the class and a ClassNotFoundException
> > will
> > > > be
> > > > > thrown .
> > > > >
> > > > >
> > > > >
> > > > > Both the OSGi framework and the Harmony do not allow the define ,
> > > imports
> > > > or
> > > > > exports of java.* classes and packages ,so a lot of examines has
> been
> > > > > removed to facilitate our purpose .
> > > > >
> > > > >
> > > > >
> > > > >
> > > > >
> > > > >
> > > > >
> > > > >
> > > > > --
> > > > > regards
> > > > > Tian
> > > > >
> > > >
> > > >
> > > >
> > > > --
> > > > http://people.apache.org/~xli
> > > >
> > >
> >
> >
> >
> > --
> > regards
> > Tian
> >
>



-- 
regards
Tian

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