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From galaxy <tian.gal...@gmail.com>
Subject Re: The OSGi-Harmony Runtime
Date Sun, 16 Aug 2009 10:30:00 GMT
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

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