Abstract

This paper discusses the implementation of a distributed execution environment, DJO, which supports the use of shared Java objects for parallel and distributed applications and provides the Java programmer with the illusion of a network-wide shared object space on loosely coupled distributed systems. DJO supports shared objects through an implementation of multiple reader/single writer write-invalidate DSM protocol in software, providing the shared memory abstraction at object granularity. Object distribution and sharing are implemented through the replication mechanism, transparently to application. The system enforces mutual consistency among replicas of an object. The main benefits of DJO are enhanced availability and performance due to the replicated object model and easier application design, as the underlying software takes care of distribution and memory consistency issues.

Author Keywords: Author Keywords: Replication; Consistency management; Concurrency control; Distributed object system; Java

Article Outline

1. Introduction

2. Requirements and related work

3. Read-replication algorithm

3.1. Consistency maintenance

3.1.1. The consistency model: release consistency

3.1.2. The coherency protocol

4. Replicated object software architecture

4.1. Communication management module

4.2. The coherency protocol

4.2.1. Memory management component

4.2.2. Ownership management component

4.2.3. Distribution management component

4.3. Synchronization module

4.4. Consistency manager

5. User interface

5.1. Create a shared object

5.2. Remove a shared object

5.3. Access a shared object in read-only mode

5.4. Receive exclusive access to the shared object

5.5. To release exclusive access and save modified object state

6. Performance evaluation

7. Conclusion and future work

appendix a

References