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Date: Tue, 24 Nov 1998 15:50:21 -0800
From: Dorothea Beringer <beringer@DB.Stanford.EDU>
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Date[November 24, 1998              ]       Recordnr[        ]
Who[ lm, ns, db
Agenda[ 

Minutes[ 

CHAIMS terminology (from last meeting):
=======================================
Synonym for megaprogrammer: composer.

Manifold:
=========
Primary authors: Forhad Arbab of Netherlands, Papadopoulis of Cyprus
Created around 1995, underwent major redefinitions.

Based on the IWIM model (ideal worker and ideal manager). This assumes
some sort of planning mechanism for selecting the best worker from a
pool of workers.
Yet in Manifold the selecting is only based on availability, no cost
factor. No notion of cost at any level.

Manifold distinguishes between a control-driven (Manifold) and
data-driven (like Linda). Data-driven: for everything that has to be
done is thrown as a tuple into a tuple space, and all processes just
always look if they can do something with the data. All processes are
friendly, and the data implementation has to be accordingly. Just for
closed systems. Problems that can arise: starvation, tuples are
unordered.

Manifold really is event driven. There are system events: Process p
raises event name of type e: e.p.name Also events are processes.
Manifold has processes (black boxes), they can be workers or managers of
other workers. The real workers are atomic: it gets data stream and
outputs output stream. The middle-tiers managers can emitt information
during processes via events.   
Ports: either input or output (never both). Openings in the black box
boundaries for data transmissions. Input: P.I,   output: P.O.  The names
are given by the black box, but it is not clear where to look them up.
Streams: Port interconnection for data only.   p.o --> q.i Just one kind
of connection. Open question: what happens semantically if q.i is
connected to several x.o and the processes behind these output ports
execute in parallel?

You have several process types, e.g. variable (in order to store
variables), sum (for making a sum over something), ...

Language:
process	V0	variable(1)	 //defines data variables with initial 
process	V1	variable(2)  // values 1 or 2
process	SUM(event overflow) //sum will generate named overflow
begin {    //this loop in the braces will run forever, until the event
V0.o -> SUM.h, V1 -> SUM.k, SUM  -> V0 }  // is generated
event: sum.overflow
end

Goal, purpose of Manifold? Implementation of compiler, run-time systems,
examples of implemented processes?


Demo-days:
==========
Main responsibilities:
- Neal: demo aircraft design
- Laurence: transportation demo
Next task: think about what should be done in both demos, which
components have to be written, ...., e.g. repository browser,
composition wizard, visualisation tool


-- 
Dorothea Beringer   Stanford University   beringer@db.stanford.edu 
          http://www-db.stanford.edu/people/beringer.html
--