Re: Ada for Boeing 777

[vanceny@dreamscape.com (Vance Christiaanse)]

In article <Pine.SUN.3.91.960219111334.8550B-100000@L10SUN8>, Frank
Petranka <fpetran@l10server.nswc.navy.mil> wrote:

> I just finished reading "Software Development for the Boeing 777" in
> the January issue of CrossTalk.

[further info and article quotes moved below]

> As someone who has used both Ada and C, I was suprised and disappointed
> that code written in Ada produced no fewer problems than code written in
> C.  Athough variables such as experience, code complexity, etc. could
> affect the results, it seems to me that they should average out on
> such a massive project.
> 
> Am I expecting too much from Ada?   

[signature and disclamer moved below]

Two observations:

1) Published accounts of software development efforts tend to be highly
   political documents.  The accounts we read have been carefully sifted
   by numerous lawyers, marketeers and program managers for statements
   that could possibly reflect poorly on anyone, so there's usualy not
   much meat left in them.  One has to read between the lines.  I don't
   know anything about this particular project, but someone may have
   decided it was not advantageous to emphaisize the benefits of Ada
   over C.

2) The quotes you provided didn't mention any actual statistics and the
   wording suggests that the Ada problems may not have been related to
   the language itself, but to the compiler and tools.  Ada is a
   wonderful language in the Reference Manual, but any specific compiler
   will have errors and weakness that can seriously harm a development
   effort.

   For example, on one very large Ada I know of, hundreds of thousands
   of lines of Ada were designed and written with one Ada compiler and
   then ported to another Ada compiler.  The designs made heavy use of
   generics because they were well-supported by the first compiler.
   Unfortunately, the second compiler implemented generics poorly and
   sometimes incorrectly.  The result was that thousands and thousands
   of lines of code had to be redesigned.  Does that count as an Ada
   problem or not?

It's too bad the news from the 777 wasn't more favorable for Ada, but
I don't think we know the whole story.

Vance Christiaanse
Cintech Consulting


[moved portions of original posting:]

> This article was written by Ron Pehrson 
> who was the manager of embedded software engineering at Boeing.  The 
> article states that 2.5 million lines of new software were developed and 
> about 70% of the code was Ada.  The remaining code was other laguages 
> "such as C or Assembly".  Mr. Pehrson writes:
> 
>   "What we have learned so far about the use of Ada on the 777 is a mixed 
>    message. ... We found no correlation between the languages used and
>    the number of problems found on the system.  We found instances where
>    Ada was used effectively, and the developers felt it substantially
>    reduced software integration problems.  In other cases, development
>    was hampered by problems with compilers and other support tools....
> 
>    The richness and complexity of the language helped knowledgeable users 
>    with mature tools achieve modest productivity gains.  However, the 
>    complexity of the language caused headaches for other users who had
>    to work through compiler problems. ..."

> 
> 
> Disclaimer: The views or opinions expressed in this article are of the user 
> and do not, in any manner, reflect that of the Navy.
> 
>             Frank J. Petranka          Naval Surface Warfare Center
>             (540)653-4849              Dahlgren, Va. 22448
>                     fpetran@relay.nswc.navy.mil