 Five years ago,  <A HREF="http://simon.cs.cornell.edu/Info/Department/Annual94/Faculty/Birman.html"> Kenneth Birman</A> and  <A HREF="http://simon.cs.cornell.edu/Info/People/rvr">Robbert van Renesse</A>  started the activity that ultimately lead to the design of Horus.  At the outset, the project was perceived as a redesign of the  <A HREF="http://simon.cs.cornell.edu/Info/Projects/ISIS">Isis</A>  group communication system.  Isis, although successful, was UNIX-specific, monolithic (and hence, inflexible), and used protocols that have subsequently been improved upon. Over the last five years, Horus evolved beyond these initial goals, becoming a sophisticated group communication system with an emphasis and properties considerably different from those of its "parent" system. <P>
