Group orientation: a paradigm for modern distributed systems.

Paulo Veríssimo and Luís Rodrigues

This paper is an extended and revised version of a paper appeared in Proceedings of the ACM SIGOPS 1992 Workshop, Mont Saint-Michel, France.


Increasing use of distributed systems, with the corresponding decentralisation, stimulates the need for structuring activities around groups of participants, for reasons of consistency, user-friendliness, performance and dependability. Although there is a significant number of group communication protocols in the literature, they are penetrating too slowly in operating systems technology. Two important reasons are: the literal interpretation generally made of the end-to-end argument, and the lack of a layer mapping end-user needs (management of replication, competition, cooperation and group membership) into what is generally provided by the communication layer: agreement and order properties.

The paper discusses both problems, proposing ways for structuring systems and defining building blocks for group-oriented activity, using concepts like object groups. It suggests that the group concept should pervade the whole architecture, from network multicasting, to group communications and management. Emerging technology will help materialise these concepts.

Also available extended report (gzip postscript), (pdf) .

Luís Rodrigues