Distributed environments based on objects: upgrading Smalltalk toward distribution

A distributed environment based on objects (DEO) is described. DEO configures an environment split in several contexts. The requirements of DEO are transparent sending of requests to remote objects that reside in different contexts, possibility of replicated objects in each context, and migration of objects from one context to another. DEO provides several kinds of replicated objects with regard to their consistency protocols. Consistency is based on the reconsideration of the equality relationship. The goal of the described implementation is compatibility with Smalltalk. No essential modifications to the standard virtual image are introduced. The interpreter has not been changed at all. Only a few primitives have been added to the virtual machine