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Welcome to the ISO home of Ada Standards

These pages are for use in the official business of ISO/IEC JTC1/SC22/WG9.

Overview of ISO/IEC JTC1/SC22/WG9

The Ada Language

This material is excerpted from a report prepared by the WG9 Convener in answer to a JTC1 action item requesting an explanation of the market relevance of all JTC1 standardization efforts.

Ada was originally developed in response to a need of the U. S. Department of Defense to reduce the number of High Order Languages (HOL) used in its systems. The specific requirements for the language emphasized high reliability, programming-in-the-large and support for real-time systems. The original Ada 87 language contains features supporting these requirements to a degree still unmatched by other HOLs. The Ada 95 revision added strong support for object-oriented (OO) programming, becoming the first internationally standardized OO language.

Ada's success in the U.S. DoD has been remarkable. The estimated number of HOLs used in DoD systems has declined from roughly 450 (in 1976) to roughly 37 (in 1996). Ada is now the most widely-used language in DoD embedded real-time applications, amounting to about 50 million source lines, and is number 2 (behind Cobol) in DoD information system applications.

Outside the defense sector, Ada's use has been more limited and primarily concentrated in areas where reliability, large systems, or real-time factors are important. For example, IBM evaluated and rated Ada above C, Pascal, Jovial and Fortran for use in programming its U. S. Air Traffic Control (ATC) applications. (An SEI study compared Ada and C++ with similar results.) Ada is also being applied to ATC development in Europe and Canada. Both in North America and Europe, Ada is arguably the language of choice (or, at least, a strong contender) for highly reliable, large, complex applications. These application domains take advantage of the rigorous specification of the Ada standard.

Other example applications include:

Interest in Ada from the educational sector is growing. A 1996 survey in the US show 345 colleges, universities, commercial and governmental institutions offered 656 college-equivalent courses in Ada.

The newsletter of the Ada Information Clearinghouse has a circulation of nearly 22,000 with nearly 50% of the readers holding positions in commercial corporations.

The US market for Ada tools and compilers is estimated to be about $200 million annually -- again, small compared to C but nevertheless significant in absolute terms.

It is estimated that approximately 5% of professional programmers in the US are Ada programmers and that about 3% of all function points in the US are programmed in Ada. Although the percentages are low compared with C, the absolute magnitudes of these numbers are huge. Market share statistics are probably less relevant, however, than consideration of the high importance of the applications for which Ada is used, applications demanding the utmost of reliability, often to protect human life. It is for this reason that the use of Ada is directed or encouraged by defense and other governmental agencies in several countries.

Furthermore, the existence of an international standard is vital to this usage. More than any other programming language, the users of Ada employ the standard itself as their basic reference to the language. The Ada marketplace has placed great importance on the existence of an unusually detailed validation suite that is driven by the specification of the standard. Vendors and users of Ada maintain a continuing and frequent dialog with SC22/WG9 in order to ensure that interpretations of the language standard are applied uniformly and that code is highly portable. In fact, the highly rigorous standardization of the language and the continuing maintenance of that standard is often cited as one of the "selling points" of the Ada language. The high degree of collaboration between the marketplace and WG9 is one of the great successes of JTC1 standardization efforts.

The International Standardization Process

Standards related to the Ada language are assigned to ISO/IEC JTC1 SC22/WG9. Completed standards are assigned labels such as the one for the Ada language itself, ISO/IEC 8652:1995. A completed document can be either an international standard (IS) or a technical report (TR). While under development, documents progress through a sequence of stages until they are finally approved. In order from beginning to end, the stages can be labeled as follows:

There are several alternatives processes used for standardization. No single process uses all of the stages listed above.

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Last updated 12 March 2008; please email comments about this page to Clyde Roby at ClydeRoby@ACM.Org