The implementation of a distributed Smalltalk

Abstract

This paper describes DistributedSmalltalk, which consists of a number of cooperating Smalltalk virtual machines distributed over a network, that provide complete distribution transparency to the image level, including transparent message passing across machine boundaries. As a result no modifications are necessary at the image level and e.g. the standard Smalltalk debugger can be used for system wide debugging. Transparent I/O is provided by means of a concept called “home objects”. The performance degradation is acceptable, due to replication and the home object concept. Replication is transparent and replication consistency is guaranteed, so e.g. for replicated class objects no compatibility checking is needed. Distributed garbage, whether containing cycles or not, is collected incrementally without any synchronization being necessary.