Re: 9X Distributed Annex? CORBA?

[stt@dsd.camb.inmet.com (Tucker Taft)]

In article <WOODRUFF.94Sep30130332@ec2226.addvax.llnl.gov>,
 <WOODRUFF@ec2226.addvax.llnl.gov> wrote:

>I'm seeking information and relevant advice about planning and building
>a distributed application using Ada94.  The application is an integrated
>control system that will deploy about 200 workstation-class computers in
>a local area net to control the next-generation high-power fusion laser.
>
>I have studied the RM's Distributed Annex, and I recognize that the
>language standard will allow me to build the system I need.  However I
>am not aware of any implementation of the Annex. I have not seen any
>claim by the GNAT team that they are planning an Annex implementation.
>Validation of commercial compilers is likely to be higher priority to
>compiler businesses than building Annexes.  Therefore my first question
>is "where and when am I likely to obtain an implementation of
>Distributed Annex?"

An implementation of the Distributed Annex is underway for GNAT.
I don't know what the schedule is.  If you want to know the plans
of other commercial vendors, you should contact them directly.
I'm sure for some of them, the Distributed Annex will be a relatively
high priority (particularly if potential customers keep asking them 
about it ;-).

>The other standard that appears relevant to my intention is CORBA.  I'm
>pretty uninformed about implementations of CORBA, so I'd welcome advice
>about what I should do to prepare for eventual use of these products.
>How will Ada interface to CORBA tools? Will CORBA implementations let me
>mix my application parts with components in other languages, or even
>with COTS software?  

Yes, that is one of the intents of CORBA.

>What is the relationship of CORBA to the distributed annex?  If the two
>are complementary strategies, then what will I need to buy and what do I
>need to learn so I can plan my application?  On the other hand if they
>are two competing paradigms, how can I choose between them, and how bad
>will be my punishment if I choose the wrong one?

The two are quite similar, and can to some extent be implemented in
terms of one another, both from a user perspective and an implementor
perspective.  That is, given an existing CORBA implementation,
an implementor, user, or third party, could use that as the basis
for the "Partition Communication System" (PCS) component of the
Distributed Annex.  Similarly, given an implementation of the
Distributed Annex, one could use that as the basis for a CORBA-compatible
IDL-to-Ada9X translator.

These days, the expert on the combination of CORBA and Ada 9X seems
to be Bill Beckwith of OIS (Objective Interface Systems, Reston, VA).  
His e-mail address is Bill.Beckwith@ois.com.

>John
>(woodruff1@llnl.gov)
>Lawrence Livermore National Lab

-Tucker Taft   stt@inmet.com
Intermetrics, Inc.
Cambridge, MA  02138