The Soprano Extensible Object Storage System

Abstract

An efficient object manager, a middle layer on top of a storage system, is essential to ensure acceptable performance of object-oriented database systems, since a traditional record-based storage system is too simple to provide object abstraction. In addition, an object storage system -object managers in combination with storage systems -should be extensible to meet the various requirements of emerging applications. In this research, we design and implement an extensible object storage system, called Soprano, in an object-oriented fashion which has shown great potential in extensibility and code reusability. Soprano provides a uniform object abstraction and gives us the convenience of persistent programming through many useful persistent classes. Also, Soprano supports efficient object management and pointer swizzling for fast object access. This paper investigates several aspects of the design and implementation of the extensible object storage system. Our experience shows the feasibility of using an objectoriented design and implementation in building an object storage system that should have both extensibility and high performance.¡ system supports only record-oriented data abstraction. That is, upper layers (if built directly on top of the relational storage system) would have to implement object abstraction, resulting in poorer performance due to increased complexity (Bancilhon et al., 1992).To overcome this problem, most OODBMSs employ a middle layer, which is called an object manager, on top of the storage system. The objective of an object manager is to reduce the impedance mismatch between upper layers (e.g., object query processor) and lower layers (e.g., storage system) by implementing object abstraction using the facilities of the underlying storage system. We summarize the basic functionalities of an object manager as follows (Bancilhon et al., 1992):