Re: Do we really need virtual machines?

On 2 Oct 2004 16:35:11 -0400, Jürgen Kahrs <juergen.kahrs@vr-web.de> wrote:


> Has anyone ever noticed that the "standard libraries" that come with
> Java and C# are attempts to recreate Unix-like Operating Systems ?


Yes, this is true. But I think that this attempts are very useful.


> Including APIs for memory, file system, scheduler, terminal, printer,
> network, clock, GUI ... O'Reilly publishes dozens of Java books. What
> are they all about ? Library details; most of them becoming obsolete
> if C# succeeds. Stuffing Java library details into my brain seems like
> a waste of brain capacity.


I don't agree with your opinion. I have done some big java
applications and I can run them with Windows, Solaris and Linux with
ANY problems and without needing to compile again. In fact, I don't
need to modify anything. And this is true because Sun has done the
effort to recreate the standard libraries and unify them in the java
library.


And if you use for example C++ , that is possible the most standard
language, with standard libraries you have more problems with
portability. Because the standard libraries don't covers all of the
functionallity you want in most of your programs. And you have to use
system dependent libaries. For example what if you want to do an app
with a GUI? (Yes, you have QT, but...) And also there are compilers
incompatibilities. A lot of times you have some code that runs well
with GNU G++ but not with MSVC.


Well, in conclusion, I think that the simple fact to do a VM don't
solves your portability in a magic way. In every platform you want to
run code, you should battle writting a VM2NativeCode and also portting
libraries if you define them. But I think that this isn't a waste of
time.


And about Nicola:


>I gain from a virtual machine that I don't already get from a good old
>compiler/runtime support/standard library chain.


I think that if you implement this you can get the same functionality
that you can get with a VM (except that you should compile in every
platform). But in constrat you will have more or at least the same
work to do that with a VM. And an advantage of a VM, is that you can
get a VM like JVM that has been already done.


Cheers,
--
Joan Jesús Pujol Espinar

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