©1998 Bionic Buffalo Corporation. All rights reserved.
Alarm Clock Server. (In this document, these will be called, simply, the client and the server.) A
server provides time-related services to its clients.
to be in local networks of co-operating, embedded systems, within single platforms among tasks
or processes, and among tasks or processes within coupled, parallel processors.
Each message from the client to the server consists of a sequence of tagged fields. Multiple
requests, responses, and notifications can be aggregated within the same message. Aggregation
improves efficiency and can be used insure that the tagged fields depart the sender or arrive at
the server at the same time. (Aggregation may also occur when the server implementation
processes requests in groups, for implementation reasons unrelated to the semantics of the
requests.)
inadequate for the requirements and were rejected. BBC plans to make the ACP standard
public, since it fills a niche not occupied by any other known standard.
multiple clocks, and specifies time values to the nearest nanosecond. On the other hand, ACP’s
tag-based design allows future extensions for greater precision or other features.
in POSIX.4. However, ACP uses a different scheme for dates. ACP dates are based on the
Astronomical Julian Day, a simple count of days since 1 January, 4713 BC. These day numbers
advance at noon (rather than at midnight).
using a count of seconds since the beginning of the year 1900. Since ACP was designed for use
by embedded systems (many of which will survive the year 2036), this achieves a significant
design goal. A 32-bit signed integer is used for day numbers.