Scaling a Shared Object Space to the Internet: Case Study of Virat

Scalability is an important issue in the construction of distributed systems. Shared object spaces provide an elegant and easy-to program abstraction for building applications. However, existing shared object spaces have been realized at the cluster level. Use of centralized components, lack of effective failure handling mechanisms, lack of efficient object lookup mechanisms as well as consistency maintenance are the key issues that inhibit scalability of existing shared object spaces. We present the case study of scaling an existing shared object space (Virat) to the Internet. Bottlenecks in Virat include the granularity of consistency maintenance and Object Meta-data Repository (OMR) failures. Both the design and implementation of Virat has been modified in order to increase the granularity at which consistency is maintained. Virat has also been redesigned such that the OMRs form a Peer-to-Peer (P2P) overlay in order to handle OMR failures and improve scalability. Experimental evaluations are presented to show that the optimized version of Virat scales better, especially over a wide-area network. In addition, this paper also explains how to develop applications over the shared object space, with code sketches.