A shared, persistent object store

Abstract

Smalltalk-80 is presented as a useful testbed for prototyping applications involving shared, persistent objects, and a detailed design of a shared persistent object store is discussed. The store is a set of named containers for object state, and it provides low-cost atomic transactions using an optimistic synchronisation technique. The standard Smalltalk-80 virtual machine is modified to support a new object class, the Transaction, and an example of a Smalltalk program using nested sub-transactions is given. Immutability of object state is identified both as an important property of objects. and a basis for producing an efficient implementation within a distributed system environment.