Raymond S. Waldrop

Distributed and parallel execution in Ada 83

Since the standardization of the Ada programming language in 1989, much research has gone into the distribution of Ada programs across a number of separate processors. However, no standard for distribution of Ada 89 programs has emerged. A new language standard, known as Ada 95, includes explicit support for the distribution of Ada programs. This paper describes the techniques and a graphical tool which allow the distribution of Ada 85 programs, using a sub-set of the methodology developed for Ada 95, with extensions to allow coarse grain parallel programming. This work is also a precursor to an implementation of the Ada 95 Distributed Systems Annex being developed by the authors in cooperation with the NYU GNAT team and France Telecom University.<<ETX>>

Future directions in Ada—distributed execution and heterogeneous language interoperability toolsets

While the Ada community has seen and embraced the development of Ada 95 [1], with its enhanced object oriented features and various annexes, much of the rest of the commercial world continues to ignore Ada as a viable tool for software system building. Efforts have been ongoing for some time to provide rationale showing the superiority of Ada 95 over other choices such as C and C++, but with limited success in the commercial marketplace. In this paper, we put forward the idea that the Ada community should focus on: 1) interoperability with components built in other languages, and 2) convenient, easy to use toolsets for composing distributed systems from heterogeneous language components.

Distributed and parallel Ada and the Ada 9X recommendations

In modern software systems development, distributed and parallel systems are of increasing importance. Much research has been done to investigate the distribution of Ada programs across a set of processors, both in loosely-coupled distributed systems and in more tightly-coupled parallel systems. To this point, however, there has been something of an idea that the support needed for distributed systems differs from that required for parallel systems. In this paper, the authors first discuss the support requirements for distributed and parallel Ada programs, and point out that the requirements for these two areas have more in common than may have been previously thought. Next, the authors discuss AdaPT (Ada plus ParTitions), a set of extensions to Ada to support distributed and fault-tolerant systems. AdaPT is used as a reference in the further discussion of the previously identified requirements for distributed systems. After this, the authors provide an in-depth discussion of the Ada 9X Distributed Systems Annex, as presented by the Ada 9X mapping/revision team in the version 5.0 draft Language Reference Manual, and the extent to which this annex fulfils the previously identified requirements.

Translating an AdaPT partition to Ada9X

This paper shows how the concept of Partitions introduced in the work of an earlier workshop [Gargaro 90a] as a possible feature to support the development of secure distributed systems in Ada9x is closely related to the abstract data type packages in the new form of Ada and can benefit from the inheritance features of the new language.It is considered that the close relationship of objects supported in the object-oriented features of the new Ada and the partitions introduced in the earlier work should be exploited in the Ada9x distribution model.

AdaPT and Ada 9X

Following an initial proposal developed at the 4th Ada Real Time Programming Workshop, Nemacolin Woodlands, 1989 and further meetings to pursue the ideas, a series of papers were published [1] [2] [3] describing and discussing possible Ada language extensions to support the development of distributable programs, and which might be considered suitable for inclusion in Ada9X. The language consisting of Ada with the extensions has been called AdaPT, which may be thought of as Ada with partitions. After introducing AdaPT, this paper describes how the AdaPT constructs can be implemented in Ada83, and then shows how they can be related to constructs proposed for Ada9X. In general, the paper endorses the ideas of the 9X team, and suggests an elegant synthesis bringing together two apparently unrelated aspects of the language (type derivation and distribution) that can provide the basis for managing distribution. 1