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From "QIU, Yin" <allenc...@gmail.com>
Subject [GSoC] Questions about the Harmony class selector idea
Date Mon, 30 Mar 2009 04:04:23 GMT
Hi Harmony folks,

I am interested in the idea of creating a minimal JRE for a Java
application, but I have some questions about it.

Having browsed the mail archive, I found I had similar thoughts to
Mike's. The key to this idea is to determine the class dependencies.
Parsing bytecode (class files or jars) would be sufficient in most
cases, except for RTTI. It's not easy (or even impossible) for this
static approach to find classes dependencies that emerge with
reflection. The description of the idea, as well as the previous
discussion on this, implies a dynamic method, which may be based on
the instrumentation mechanism, that is, to find dependencies by
running tests. Of course, this puts obligations on the developers to
write tests with 100% code coverage. But it seems to be a bit
contradictory. As harmony class selector is an *automatic* way to
build a JRE of minimal size, the correctness of it relies strongly on
the hypothesis that human beings make no faults.

So my question is: What is the most important objective of Harmony
class selector? Better code coverage or a minimal JRE? If it is the
latter case, I would like to suggest a hybrid approach. We first parse
the bytecode, get a preliminary class dependency graph, write specific
programs to test RTTI-related code, and finally use instrumentation to
find if we missed some dependencies.

I hope I made myself clear. Any comment is greatly appreciated.


Regards.

-- 
Yin Qiu
Nanjing University, China

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