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From "Xiao-Feng Li" <xiaofeng...@gmail.com>
Subject Re: Re: Re: [general] features
Date Thu, 08 Jan 2009 07:47:10 GMT
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

I actually had made this work with another simpler JVM implementation.
It should be not difficult to achieve with Harmony.


> ------------------
> 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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