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From "Ian Rogers" <rogers.em...@gmail.com>
Subject Re: Re: Re: [general] features
Date Thu, 08 Jan 2009 08:01:58 GMT
2009/1/8 Xiao-Feng Li <xiaofeng.li@gmail.com>

> On Thu, Jan 8, 2009 at 12:52 AM, Rui Chu <rchu@nudt.edu.cn> wrote:
> > Ignoring the native APIs, can we take the heap, stack, byte codes, TLS
> and other mgmt metadata in a JVM as an status information?  Can we store the
> status in a disk file, and restore them later to perform an approximate
> "hibernate"? Maybe it is rather simple and coarse, while it would be
> attractive even when it only works for a few simple applications.
> > After all, JVM is also a simple machine model rather than a full layered
> OS and system hardware...
>
> I actually had made this work with another simpler JVM implementation.
> It should be not difficult to achieve with Harmony.
>
> Thanks,
> xiaofeng


There is a similar project using Jikes RVM:

http://www.agentgroup.unimore.it/didattica/curriculum/raffaele/mobility_work.html

As I understand it they are using a pre version 3 Jikes RVM and so don't yet
have the option of using the Harmony class library.

Regards,
Ian

> ------------------
> > Rui Chu
> > 2009-01-08
> >
> > -------------------------------------------------------------
> > 发件人:Jack Cai
> > 发送日期:2009-01-07 17:27:07
> > 收件人:dev
> > 抄送:
> > 主题:Re: Re: [general] features
> >
> > So to quickly answer your questions -
> >
> > #2: No, neither SUN JVM nor Harmony JVM support such "hibernate"
> operation.
> > JVM does not have an abstract Hardware level, even though it does manage
> the
> > memory and threads for a running process. So it is not a "real" operating
> > system. It accesses resources by calling the hosting OS's native APIs
> > directly. As a result, it's not as easy to hibernate a JVM as we do with
> > Windows, VMWare, etc.
> >
> > #3: Yes, sandbox is the built-in Java security model. You can achieve
> what
> > you described through a customized SecurityManager. You can search google
> to
> > find enough to read.
> >
> > - Jack
> >
> > 2009/1/7 Rui Chu <rchu@nudt.edu.cn>
> >
> >> Thank you, Xiaofeng.
> >>
> >> About Java Isolation, I am not sure whether SUN JVM implements it. If
> not,
> >> maybe the benefit of Isolation is still trivial to motivate the guys in
> SUN,
> >> although it looks nice in the proposal.
> >>
> >> About the second question, as you know, VMWare, as well as other
> >> system-level virtual machines, can suspend the guest operating system
> when
> >> you press the 'suspend' button. You can also resume it later, or even
> resume
> >> it in another host system. This feature really looks charming in my
> mind.  I
> >> think JVM can also support it more easily because JVM has a relative
> simpler
> >> architecture then the system-level VMs (although it is still complex). I
> >> wonder if current Harmony or SUN JVM could do that.
> >>
> >> The sandbox in my third question does not only mean Applet. In my
> vision,
> >> it should support general java applications. The execution of the
> >> application is monitored and restricted, especially the operations
> through
> >> JNI. For example, the java application cannot  access the native file
> system
> >> with the same privilege of JVM, and it can only accesses a virtualized
> file
> >> system instead. Is there any project or plan in Harnony or SUN JVM to do
> >> that?
> >>
> >> Thanks again, Xiaofeng. I have read some documents and source codes. But
> >> the souce codes can only prove what has been done in Harmony, while
> cannot
> >> tell me what is still not implemented. :)  If possible, I want to
> continue
> >> to discuss this topic with you. Waiting for you kind response. Anybody
> else
> >> want to join the topic are also appreciated.
> >>
> >> ------------------
> >> Rui Chu
> >> 2009-01-07
> >>
> >> -------------------------------------------------------------
> >> 发件人:Xiao-Feng Li
> >> 发送日期:2009-01-07 08:35:56
> >> 收件人:dev
> >> 抄送:
> >> 主题:Re: [general] features
> >>
> >> Rui, thanks for your interests in Harmony. My personal opinions are
> >> inlined below.
> >>
> >> On Wed, Jan 7, 2009 at 12:39 AM, Rui Chu <rchu@nudt.edu.cn> wrote:
> >> > Hi,
> >> > I am a new comer of JVM and Harmony. Since I have just learnt Harmony
> for
> >> a few time, I wonder whether Harmony(especially the VM) has implemented
> or
> >> has been interested in the features as follows.
> >> > 1. SUN has proposed Java Isolation for a long while, and related
> >> specifications have also been released. Unfortunately I cannot find any
> >> support for it in SUN JVM till now. Has Harmony implemented or planned
> to do
> >> that? Or maybe SUN has implemented but I do not know it yet.
> >>
> >> [XF] I personally don't really see the needs to implement Isolation in
> >> Harmony. But it is welcomed if anybody wants to have a try and I'd
> >> like to help. I had some experience in it.
> >>
> >> > 2. Does SUN JVM or Harmony support to suspend, serialize and resume
> the
> >> JVM? In other words, a JVM can suspend the execution of itself and
> >> bytecodes, transfer the execution status into an image file and resume
> it
> >> later. Assuming the external environments such as file system or network
> >> connection still keeps.
> >>
> >> [XF] If I understand you correctly, the feature you described is the
> >> fundamental feature of a JVM for garbage collection and exception
> >> throwing. So all serious JVMs have it.
> >>
> >> > 3. Does the sandbox support appear as an independent project, or has
> been
> >> integrated in Harmony? Where can I find more documents about the sandbox
> in
> >> Harmony?
> >>
> >> [XF] I am not sure what you mean with sandbox. If you mean Applet
> >> support, yes, Harmony has it (almost done).
> >>
> >> > In general, I want to know whether Harmony planned to be another (open
> >> source) implementation of SUN JVM, or has its special features beyond
> the
> >> latter? I am not familiar with both SUN JVM and Harmony, so my question
> may
> >> be naive :)  Your kind and patient answers are appreciated.
> >>
> >> [XF] Please read some documents on Apache Harmony in its website. That
> >> will help you to have a basic understanding. Harmony is an open source
> >> Java SE implementation under Apache license. I personally think
> >> Harmony wants to be compatible at first, and might have some special
> >> features.
> >>
> >> Thanks,
> >> xiaofeng
> >>
> >> > Thanks a lot!
> >> >
> >> >
> >> >
> >> >
> >> > Rui Chu
> >> >
> >> >
> >> >
> >>
> >>
> >>
> >> --
> >> Managed Runtime Technology Center, Intel
> >>
> >>
> >
>
>
>
> --
> Managed Runtime Technology Center, Intel
>
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