On Thu, Jan 8, 2009 at 12:52 AM, Rui Chu <[email protected]> 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 > ------------------ > 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 >> >> > -- Managed Runtime Technology Center, Intel
