Organizing and typing persistent objects within an object-oriented framework

Conventional operating systems provide little or no direct support for an efficient persistent object system implementation. The authors have built a persistent object scheme using a customization and extension of an object-oriented operating system called Choices. Both conventional file systems and persistent object systems are constructed within the same framework for the storage of persistent data. The persistent object store supports a wide range of persistent object sizes, extensible sets of persistent object types and automated garbage collection and associates each object with its class and operations. To improve performance, collections of persistent object can be accessed as an aggregate. Light-weight persistent objects may be clustered within persistent object containers. In this paper the authors describe how persistent objects are named and used within Choices, and three areas in which persistent object support differs from file system support: storage organization, storage management, and typing.<>