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...
------------------ 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 <[email protected]> > 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 <[email protected]> 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 > >
