NRC CSTB Ada Public Briefing Summary

NRC CSTB Ada Public Briefing Summary

[Software Engineering News]

Computer Science and Telecommunications Board
National Research Council
210 Constitution Avenue, N.W., Washington, D.C.  20418

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Committee on the Past and Present Contexts for the Use of 
Ada in the Department of Defense

Barry Boehm, Chair
University of Southern California

Theodore Baker
Florida State University

Wesley Embry
Silicon Graphics, Inc.

Joseph Fox
Template Software

Paul Hilfinger
University of California at Berkeley

Maretta Holden
Boeing Defense and Space Group

J. Elliot B. Moss
University of Massachusetts at Amherst

Walker Royce
Rational Software Corporation

William Scherlis
Carnegie Mellon University

S. Tucker Taft
Intermetrics, Inc.

Rayford Vaughn
Electronic Data Systems Corporation

Anthony Wasserman
Interactive Development Environments, Inc.

Barbara Liskov, Special Advisor
Massachusetts Institute of Technology

Staff

Paul Semenza
Study Director, CSTB

Ada and Beyond: Software Policies for the Department of 
Defense

What should the Department of Defense do about the Ada 
programming language?  Despite the language�s technical 
capabilities, it has not been widely used outside of 
military and other safety-critical applications, as was 
hoped when the language was developed in the 1970s.  The 
Defense Department�s policy on programming languages, which 
requires the use of Ada for all new software development, 
has resulted in many conflicts and has not been implemented 
evenly.  Meanwhile, commercial software applications have 
grown rapidly, and do not generally use Ada.

The Committee on the Past and Present Contexts for the Use 
of Ada in the Department of Defense was created by the 
National Research Council�s Computer Science and 
Telecommunications Board to review the current policy, and 
to examine the role of Ada in software development.  The 
study was requested by the Office of the Assistant secretary 
of Defense for Command, Control, Communications, and 
Intelligence.  Released today, Ada and Beyond: Software 
Policies for the Department of Defense presents the 
committee�s findings and recommendations.

The committee concluded the vigorous support of Ada would 
benefit warfighting systems, and recommends that the 
Department of Defense should continue to use and promote Ada 
in such systems.  However, the committee found significant 
problems with the two primary components of the Defense 
Department�s current strategy for Ada.  First, the current 
programming language policy requires the use of Ada for all 
new defense software, which the committee finds to be overly 
broad in scope.  Second, the Defense Department�s plan to 
discontinue investments in both Ada technology and user-
community support will weaken the Ada infrastructure, and 
will work against any requirement to use Ada in the future.

In summary, Ada and Beyond:  Software Policies for the 
Department of Defense concludes that the Defense Department 
should  take the following steps regarding Ada:

1. Continue to require Ada for its warfighting software and 
drop the Ada requirement for its other software.  In 
commercially dominated areas, using Ada is generally less 
cost-effective than using other languages.  Requiring the 
use of Ada in these areas would place the Defense Department 
at a competitive disadvantage.  In warfighting application 
areas, however, Ada�s technical capabilities for real-time, 
high assurance custom software are generally superior to 
those of other languages.  The Defense Department�s 
investments in Ada to date have created a set of Ada-based 
production factors that give its system advantages in these 
areas.

2. Provide roughly $15 million per year for Ada 
infrastructure support, or drop the requirement to use Ada 
entirely.  The commercial marketplace will not sustain a 
robust Ada infrastructure.  However, a relatively modest 
($15 million per year) investment at the margin by the 
Defense Department would be sufficient to sustain a robust 
Ada infrastructure for warfighting applications.  The 
Defense Department�s inventory of more than 50 million lines 
of warfighting software must either be maintained in Ada or 
converted to another programming language.  The recommended 
investment is modest with this maintenance burden.

3. Make programming language decisions in the context of a 
Software Engineering Plan Review process.  The choice of 
programming language is one component of the software-
engineering process, and should be considered in the broader 
context of decisions regarding architecture, software reuse, 
and software process management.

In the course of this study, the committee also concluded 
that the currently available data are insufficient, on their 
own, to accurately determine the impact of programming 
language choice on the outcome of defense programs.  
Committee briefings also highlighted the difficulty that 
program managers have in finding data on which they can make 
informed decisions.  Based on the limitations of 
availability data, the committee has made an additional 
recommendation that the Defense Department institute a 
corporate effort to collect software metrics to guide future 
policy and management decisions.

The committee developed its recommendations, presented in 
detail in Ada and Beyond:  Software Policies for the 
Department of Defense, in light of changes in the 
environment for military software development.  A decade 
ago, the policy preference for Ada had some merit.  Most 
software was custom made, and Ada had a good track record in 
delivering custom software with higher quality and lower 
life-cycle costs.  However, custom Ada solutions are no 
longer competitive in many application areas, due to several 
trends.  First, software solutions increasingly depend on 
commercial-off-the-shelf, or COTS, software, which provides 
much of an application�s information infrastructure, 
including operating system, database management, networking, 
user interface, and distributed processing functions.  Much 
of this software is written in programming languages other 
than Ada, that often do not have readily available 
interfaces to programs written in Ada.

Second, software for many application areas is increasingly 
developed in so-called "product-line" architectures, which 
enable software assets to be reused across families of 
applications.  These product-line solutions are driven by 
strongly coupled "production factors," including software 
components, processes and methods, human resources, and 
expertise in particular domains.  In warfighting 
applications areas such as weapon control and electronic 
warfare, there is little commercial development, and the 
Defense Department has established a strong community of 
warfighting software developers whose production factors are 
oriented to Ada.  However, for the numerous defense 
applications in which the market is dominated by commercial 
solutions, such as finance and logistics, production factors 
have been built around programming languages other than Ada 
putting solutions at a disadvantage.

Several other factors have strongly influenced the 
committee�s findings and recommendations.  One is the 
Defense Department�s increasing emphasis on information 
dominance.  According to Secretary of Defense William Perry, 
the Defense Department�s warfighting strategy "sustains and 
builds on ... the application of information technology to 
gain great military leverage to continue to give us [an] 
unfair competitive advantage."  A second factor is that the 
Defense Department now has more than 50 million lines of 
operational weapon systems software written in Ada, with a 
great deal more under development.  Most of this software is 
in critical warfighting applications areas.  There are no 
quick and cheap ways to translate this software into other 
languages.  Polices and investment strategies that weaken 
Ada support for this software are very risky.

A third factor is that, while language proliferation has 
decreased, "polylingualism" is here to stay.  One goal of 
developing Ada was to reduce the proliferation of 
programming languages used in defense systems, estimated to 
be approximately 450 in the 1970s.  The number of languages 
used in defense systems has indeed decreased.  The use of 
machine and assembly languages has diminished, and the 
number of third-generation languages in use has been 
reduced.  However, there has been a rapid increase in 
development of fourth-generation languages by the commercial 
sector, and increased use of these languages by defense 
programs.  A final factor is that choosing a programming 
language is one of several key software engineering 
decisions.  The requirement to use Ada and the waiver 
process both isolate programming language decisions from 
other key software engineering decisions.  Modern software 
engineering considerations include the choices of computer 
and software architectures, COTS components, and milestone 
schedules.  This arrangement creates and incentive for 
defense programs to make decisions that are not optimal for 
the Defense Department as an organization.  Future 
programming language decisions need to be part of an 
integrated software engineering process.



This report will be available electronically on the World 
Wide Web in mid-November at <www2.nas.edu/cstbweb>.  Paper 
copies will be made available in December.



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