This paper describes three low-level services that are useful in structuring
the implementation of fault-tolerant group communication services. These low
level services are event mapping, vector timestamp, and
event history. The event-mapping service provides support for creating
and manipulating lists of related distributed events, the vector-timestamp
service allows servers to infer precedence relations among distributed events,
and the event-history service enables one to record, access, and manipulate
distributed events that are causally related. In our experience, we have found
that these low-level services are simple to use and general enough to simplify
the design and implementation of many fault-tolerant group communication
services. For each service, we briefly describe its functionality and the set
of operations exported by it, outline the algorithms and data structures used
to implement it, and give
concrete examples of how it is used in implementing some real fault-tolerant
group communication services.
Copyright © 1996 Shivakant Mishra