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From "Rui Chu" <r...@nudt.edu.cn>
Subject Re: Re: [general] features
Date Wed, 07 Jan 2009 07:53:00 GMT
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

发件人:Xiao-Feng Li
发送日期:2009-01-07 08:35:56
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


> Thanks a lot!
> Rui Chu

Managed Runtime Technology Center, Intel

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