The Horus project has developed a modular and extensible process-group communication system, addressing the requirements of a wide variety of robust distributed applications.
Horus provides a framework for the development of distributed applications based on group communications, a style of computing that can arise in fault-tolerant systems, managed distributed systems, applications that exploit data replication or coherent caching, and groupware. Within the overall Horus framework a large collection of system and application protocols have been developed that allow the application designer to construct a communication module that exactly meets the application requirements at minimal cost.
The Horus project was originally launched as an effort to redesign the Isis group communication system, but has evolved into a general purpose communication architecture with advanced support for the development of robust distributed systems in settings for which Isis was unsuitable, such as applications that have special security or real-time requirements. Besides the practical uses of our software, the project has contributed towards the theory of virtually synchrony, a runtime model used for our implementation of data replication and fault-tolerance. At the same time, our software is much faster and lighter weight than the Isis system.
Horus exists as two systems: an initial version coded in C, which can be used for research purposes at no fee but has restricted commerical rights, and a new version called Ensemble, written in ML but usable from many other languages, which is available for all classes of users at no fee. Ensemble is actively under development and we will do series of releases over the fall of 1996 and spring of 1997. By early in 1997, Ensemble will be an outstanding environment for building Java-based groupware applications that do multimedia conferencing on the Web.
Horus and Ensemble are designed to be platform independent, and are available for different classes of workstations, personal computers, parallel processors and on next-generation cluster environments using standard high-speed communications networks.
The Horus effort collaborates closely with many other distributed systems projects, including Transis, NavTech, and the StormCast and TACOMA projects. Links to these and other projects can be found elsewhere in these pages.
¹ Final sentence in the Hyme to Osiris from the Papyrus
of Ani, better know as the Book of the
Comments to Werner Vogels