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                    Seminar Announcement

            School of Computer Science, CECS
             The Australian National University
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Date:  Thursday, 09 April 2009
Time:  4:00 pm to 5:00 pm
Venue: Room N101, CSIT Building [108]


Speaker: Tony Hosking, Computer Science Dept., Purdue University

Title:   Pervasive Virtualisation of Java Classes with
         Application to Transparent Distribution

Abstract:
   The transformation of large, off-the-shelf Java applications
   to support complex new functionality essentially requires 
   generation of an entirely new application that retains the
   execution semantics of the original.

   I will describe our framework for whole-program transformation
   of Java applications to support transparent distribution.  Our
   transformations rely on pervasive virtualisation of field
   access and method invocation.  Allowing the interposition of
   arbitrary code on object access permits straightforward
   representation of remote references, persistent object
   identifiers, object migration and storage (whether on disk
   or across the network), and arbitrary per-instance
   instrumentation.  Yet transformations that introduce the new
   virtualised object model are complicated for Java by the
   presence of code that cannot be rewritten to conform to the
   new object model, whether because it is native, or nominally
   implementation-dependent and tightly integrated  with the
   Java VM implementation.  These constraints lead us to a
   framework for classifying Java classes systematically so that
   all instances can be virtualized, though some may need to
   retain their original representation for manipulation by
   unmodifiable code.

   We also discuss the proxy-based object model that allows
   remote Java objects to be referenced in the same way as
   those residing on the current virtual machine, the
   optimizations that allow us to bypass proxies in the case
   of purely local or remote objects, and the mechanisms
   needed to guarantee that static data remain unique in a
   distributed system. We then detail some of the more
   interesting features involved when implementing this
   object model in rewritten bytecode, including trans-
   formations required within method bodies and coordination
   between bytecode and the run-time system that distributes
   an application across the network.

Biography:
   Tony Hosking is an Associate Professor of Computer Science
   at Purdue University in the USA, though he happily identifies
   himself as an Aussie and is currently on sabbatical leave
   as a Visiting Fellow at the ANU.  His interests focus on
   the design and implementation of clean run-time programming
   abstractions, including object-orientation, persistence,
   distribution, automatic memory management ("garbage
   collection"), and transactional memory, along with the
   systems that support them including languages, compilers,
   optimisations, run-time systems, operating systems, and
   hardware support. 


URL: http://cs.anu.edu.au/lib/seminars/seminars09/dept20090409



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