Re: Books about the Distributed Systems Annex ?

[Dale Stanbrough <dale@goanna.cs.rmit.EDU.AU>]

Tucker Taft writes...

<<Dale Stanbrough (dale@goanna.cs.rmit.edu.au) wrote:

: Tom Moran writes:

: "You might look at Chapter 14 of "Concurrency in Ada", Burns & Wellings,
:  Cambridge University Press, 1995, ISBN 0 521 41471 7"

: I seem to remember that Tucker Taft commented that this book's analysis
: of the DSA was overly pessimistic. 

I don't remember that ;-).  I heartily recommend the above book.

: Dale

-Tucker Taft   stt@inmet.com   http://www.inmet.com/~stt/
Intermetrics, Inc.  Burlington, MA  USA>>



Here's a reminder :-) (what an amazing hoarder i am!)


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From: stt@copperfield.camb.inmet.com (Tucker Taft)
Subject: Re: More on Distributed Systems Annex
Date: Fri, 13 Sep 1996 15:08:22 GMT
Lines: 53

Dale Stanbrough (dale@goanna.cs.rmit.edu.au) wrote:

[...]

: The book Concurrency In Ada by Burns and Wellings includes a chapter on this
: and concludes...

: 	"The most severe limitation of the Ada partition model is that
: 	 partitions are not first class language objects. Partition types
: 	 cannot be created and therefore instances of partitions...
: 	 cannot be expressed"

: (this is an excellent book and well worth while buying)

I don't think it is quite as grim as Burns and Wellings might imply.  First
of all, if you want multiple instances of things, you can declare a type
or a generic.  The distributed annex supports dynamic binding between
partitions using either remote access-to-subprogram or remote 
access-to-classwide.

The other, perhaps more important point is that the partition IDs
are only really needed for initiating requests, not for replying.
So even if every client ended up with the same partition ID, at
a lower level presumably the PCS could make a distinction between them.

In any case, it would seem a natural extension to explicitly support
the notion of "client" partitions by allowing a "client" partition
to have a Partition ID assigned dynamically, perhaps by a
new version of Establish_RPC_Receiver with an OUT parameter
rather than an IN parameter for the Partition_ID.

: Dale

-Tucker Taft   stt@inmet.com   http://www.inmet.com/~stt/
Intermetrics, Inc.  Cambridge, MA  USA
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