Subject: Comments: CAWG report

From: [email-masked] (Omer F Rana)
Date: Tue, 6 Oct 1998 19:18:22 +0100 (BST)

Hi,

Comments: Concurrency and Applications Working Group Report

The report outlines some restricting with the JVM, and mentions
possible solutions -- however, the solution of removing functionality
from the JVM was never considered. For instance, at the recent
'Java for high performance networking computing' workshop at EuroPar98,
Matt Welsh identified a way of removing features from the JVM (for
use in network interface cards (NIC) -- see:
"U-Net/SLE: A Java-based User-Customizable Virtual Network Interface",
download from http://www.cs.cf.ac.uk/hpjworkshop/)
with subsequent customisation by downloadable code. Matt et. al. implemented
a cut down version of the JVM as JIVE, where their design goal was
to create, "a small run time memory footprint, and reasonable performance
even on a slow processor". Although the idea of encoding for repeated
types was mentioned in the report -- no mention is made of what other features could
be trimmed within the VM. For certain application types, as is shown
in the JIVE example, other features in the JVM could be removed.

In section 1.1, Solution part, the idea of providing a 'reset' method
which would allow information on sent objects to be removed is mentioned.
How does this addition deal with two objects of the same type, sent
in non-subsequent calls? The first 'reset' method presumably provides a
type,object pairing right? 

I am also not sure about the practicality of providing a user defined 
serialisation routine. Is this safe?

Throughout the report -- no mention is made of Java security or the 
restrictions imposed by the SecurityManager. Some reference occurs
in the 'Seamless' computing section on authentication -- but I would
have assumed that implementing any user-level-service (section 2.3)
would cause security problems.

Also, we would like to work on a DataMining benchmark at Cardiff -- 
if this is possible. I know Mark Snir's group was involved in this --
can we work on this jointly? No mention was made of a DataMining benchmark
in the report.

regards
Omer

-- 
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