An Ada library to program fault-tolerant distributed applications

Abstract

This paper describes a library written in Ada which facilitates the construction of fault-tolerant distributed applications based on the active replication paradigm [18]. The library, called Group_IO [10], offers a simple interface to the implementation of reliable, atomic, causal, and uniform multicast. The work on Group_IO has been motivated by our experience with Isis [3] and similar reliable multicast frameworks. The library allows also client-server interactions where the client may be a group — this interaction is not supported by ISIS- and relies on an own consensus protocol [8, 9] to implement the uniform broadcast protocols. Group_IO is the base on which the programming language Drago [2, 15, 16] has been implemented, however it does not require Drago for its use.