PJRMI: Remote Method Invocation for a Persistent System
Susan Spence
Abstract:
This paper describes PJRMI: support for remote method invocation in the context of the object-oriented, orthogonally-persistent system of the PJama project. It examines the issues raised by combining orthogonal persistence with distribution. An evaluation is made of the current implementation and an indication is made of the challenges ahead.
Copyright 1999 IEEE. Published in the Proceedings of the International Symposium on Distributed Objects and Applications (DOA'99), 5-6 September 1999, Edinburgh, Scotland, UK.
Policies for Passing Objects by Copy between Widely Distributed Persistent Stores.
Susan Spence
Abstract:
Existing distribution support typically requires programmers to make
decisions statically about how objects of a particular class are to be
accessed remotely. Where these objects are persistent, greater
flexibility is required in the specification of remote object access.
This is necessary to cope with the remote use of persistent objects,
that have potentially large and complex object graphs, by a variety of
applications and in a variety of distributed environments over the
lifetime of the store.
This paper presents distribution support integrated with orthogonal persistence for Java, providing a range of policies for deciding when objects are copied between widely-distributed applications running over persistent stores. Use of these policies promotes separation of architectural issues, since they can be adopted dynamically for most object classes to suit a particular application task and local or wide area network. The policies are evaluated, performance figures are given and the benefits of their use in this and other programming contexts are described.
Submitted for publication, 1999.
Porting a Distributed System to PJama: Orthogonal Persistence for Java
Huw Evans and Susan Spence
Abstract:
This paper describes the experience of porting a 25,000 line distributed Java program to version 0.3.5.1 of the orthogonally persistent programming environment PJama. The port was performed in two stages. The first stage, changing the source code, took two days. The second stage, ensuring the ported program exhibited a suitable run-time behaviour, took one week. This paper discusses the main changes that were required in moving from a distributed system with support for persistence via serialization to one that supports an implementation of orthogonal persistence with support for distributed programming.
Published in the Proceedings of the Third Persistence and Java Workshop (PJW3), September 1998, Tiburon, California.
The Design of a new Persistent Object Store for PJama
Tony Printezis, Malcolm Atkinson, Laurent Daynes, Susan Spence and Pete Bailey
Published at The Second International Workshop on Persistence and Java(tm) (PJW2), August 1997, Half Moon Bay, California.
Distribution Support for PJama
Susan Spence
Abstract:
The work on the PJama project includes investigation of appropriate support for distribution in a large-scale, distributed,
persistent system for Java. The aim is to address problems raised by the combination of persistence with distribution. The
extension of the principles of orthogonal persistence to a distributed system are examined in this paper and appropriate support for
distribution is introduced to deal with issues of referential integrity, management of distribution-related code and copying of
objects between distributed, persistent stores.
Presented at the Workshop on Persistence and Distribution in Java, 20 October 1997, INESC, Lisbon (Portugal), organized by the PerDiS Esprit Project
A Scalable Model of Distribution Promoting Autonomy of
and Cooperation between PJava Object Stores
Susan Spence and Malcolm Atkinson
Abstract:
Distributed persistent systems often provide transparency of distribution at the
cost of autonomy of object stores, efficiency of cooperation between
them and scalability of the system. We propose a flexible model of
distribution to support scalable persistent application systems that
allows for both autonomous stores with low-cost, limited commitments to
other stores and sophisticated models of interaction on a limited scale with
maintainable inter-store references. Scalability would be provided by
exposing the distribution of stores, with the use of extended
URLs as global names. Autonomy of a store would be preserved by
making it possible for the store to retain control over the objects it
makes available for remote use.
Copyright 1996 IEEE. Published in the Proceedings of the Hawaii International Conference on System Sciences, 7-10 January 1997, Aston Wailea Resort, Wailea, Hawaii, USA.
An Orthogonally Persistent Java
M.P. Atkinson, L. Daynes, M.J. Jordan, T. Printezis and S. Spence.
Published in ACM Sigmod Record, Volume 25, Number 4. December 1996.
Distribution Strategies for Persistent Java
Susan Spence
Published in the Proceedings of the First International Workshop on Persistence and Java(tm) (PJW1), September 1996, Drymen, Scotland.
Design Issues for Persistent Java:
a type-safe, object-oriented, orthogonally persistent system
M.P. Atkinson, M.J. Jordan, L. Daynes and S. Spence
Abstract:
The object-oriented programming language Java is receiving much attention and is
likely to become a popular commercial programming language because of its regul
ar structure, safety features and modern constructs. It presents a novel opport
unity, because of this safety and potential popularity, to make orthogonal persi
stence defined by reachability widely available. We report on a design for a sy
stem that provides such persistence with no changes to the Java language. The d
esign includes ambitious goals for transactional flexibility but also includes s
imple transactional behaviour sufficient for many applications. We report on se
veral issues that were encountered during the design which as yet have no obviou
s solution. An outline of the proposed implementation is also given.
Published in the Proceedings of the Seventh Workshop on Persistent Object Systems, 29-31 May 1996, Cape May, New Jersey, USA.