On 11/26/2010 01:02 PM, Karsten Silz wrote:
On Nov 26, 9:52 am, Fabrizio Giudici<[email protected]>
wrote:
As a mere technical discussion here, it's interesting to learn that
probably Dalvik has no technical justification for its existence, other
than some legal points.
Dalvik is optimized for class sharing between VM instances, something
"regular Java" hasn't achieved so far (maybe after modularization in
JDK 8). Imagine ten Android apps running at the same time, and they
all would load their own set oft the same Android SKD collection /
network / file classes... This is especially important on memory-
constrained devices like phones.
Internally, there's one VM instance (called "Zygote") launched at boot
time that loads all the core classes. Other VMs are spawned off of
this and use these core classes. More in this PDF on page 5:
http://davidehringer.com/software/android/The_Dalvik_Virtual_Machine.pdf
I know - in fact I said that I'm not backing nor neglecting Oracle's
point, and that there is much more to be said than "mere" performance.
But I do expect Google to post back, and Oracle eventually going further
with some posts. My idea - expressed many times - is that Oracle wants
to force Android to the OpenJDK way (*) and get parts of the cake; for
this reason, the technology should be still successful, so I suppose
they have studied all the required hacks. Let's see.
BTW, "regular Java" hasn't achieved this goal if we talk about
Sun/Oracle Java, but Apple did that several years ago, before Google. I
think IBM's JDK also does this since a few years. Anyway, back to Apple,
since Apple is now supposed to contribute to OpenJDK, it would be
interesting to understand whether this technology is now accessible by
Oracle.
(*) Talking about OpenJDK for what concerns the codebase; it's
interesting that Oracle's post instead talks about JavaSE, which is not
open. In any case, I suppose that the TCK field-of-use restrictions are
a sufficient guarantee for Oracle to eventually keep open an
OpenJDK-based successful technology for Android and still be protected
from forks. If we want to push even further in speculations, given the
latest articles about Google allegedly losing control on Android because
of some successful forks by a few large operators, I'm guessing whether
Google is considering that an agreement with Oracle, while it would
force them to share the jewel with Oracle, would protect from any other
kind of fork, even enabling them to sue forkers...
--
Fabrizio Giudici - Java Architect, Project Manager
Tidalwave s.a.s. - "We make Java work. Everywhere."
java.net/blog/fabriziogiudici - www.tidalwave.it/people
[email protected]
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