andy@minster.york.ac.uk (Anthony Gargaro) (09/15/87)
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2nd INTERNATIONAL WORKSHOP
ON REAL TIME ADA ISSUES
Devon, England, 1 - 3 June 1988
(Sponsored by Ada UK in cooperation with ACM SIGAda)
ORGANIZING COMMITTEE
Angel Alvarez Ted Baker John Barnes
Mark Dowson Gerry Fisher Anthony Gargaro
Andy Wellings
The first International Workshop on Real Time Ada Issues
identified a number of critical issues that impact on the use
of Ada in embedded systems, particularly in `hard' real-time
applications. Interim recommendations for addressing these
issues appear in the Workshop proceedings (ACM Ada Letters,
October 1987).
The 2nd Workshop will examine the critical issues in greater
depth. It is expected that the participants will have specific
proposals which can be analyzed during the workshop with a
view to agreeing recommended courses of action to various
segments of the Ada community. The issues to be considered
include:
Scheduling mechanisms
Hard real-time systems may combine periodic transactions which
must meet regular deadlines with sporadic transactions with
defined worst-case response times. Such deadline scheduling is
difficult to program with Ada's existing timing and priority
mechanisms.
What mechanisms are needed for satisfactory handling of
deadlines for both periodic and sporadic transactions?
What new or modified Ada language features are needed to
implement these mechanisms?
Asynchronous transfer of control
Rapid event driven mode shifts and certain kinds of error
recovery require a task asynchronously to affect the flow
control of another task in ways that cannot be conveniently
achieved by abort alone. Polling strategies reduce task
readability and do not, in general, guarantee fast response.
Are additional language constructs, such as a FAILURE
exception, needed?
How can these constructs be defined so that anomalous cases
eg when interacting with other exceptions, are minimized?
Distributed execution: re-configuration and recovery
Ada, in common with most programming languages, does not
directly address the problems of distributed execution. In
particular, Ada provides no mechanisms to support dynamic re-
configuration of a distributed system in case of partial
hardware failure.
Should re-configuration be achieved transparently by the
run-time system, by a separate mechanism eg system
generation and re-generation, or under the control of the
application program?
What additional language constructs, if any, are needed?
The workshop, which will be held at the Manor House Hotel,
Moretonhampstead, Devon, UK, will consist of three days'
intensive consideration of these issues by, at most, 35
participants. Prospective participants should submit a maximum
3 page position paper by 14 December 1987, explicitly
addressing one of the workshop issues and suitable for
publication in the proceedings. A small number of participants
will be requested to prepare short keynote presentations to
initiate discussion. Position papers (6 copies or electronic
mail in UNIX troff form if possible) should be sent to:
Andy Wellings
Computer Science Dept, University of York,
Heslington, York YO1 5DD ENGLAND.
Tel: +44 904 430000 ext 305
Email: andy@minster.york.ac.uk
or
(Electronic mail only)
Anthony Gargaro
Email: Gargaro@ada20.isi.edu
Submission of papers by electronic mail is encouraged
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