In a type secure persistent programming system, all data is governed for its entire lifetime by a single type system. The universality of the persistent type system has implications in terms of both the modelling and protection provided by the type system itself, and also presents some new challenges in terms of implementation. With respect to modelling, the persistent type system must be sufficiently flexible to allow the modelling of activities normally provided by untyped support systems. Such activities include, for example, the linking of separately prepared program units, and file system access protection. Methods of achieving such flexibility whilst maximising safety include the controlled use of infinite unions, parametric and inclusion polymorphism. With respect to protection, the increased role of a type system means that any protection mechanisms programmed at a high level may be fully relied upon to protect the data for its lifetime, as access from outside the constraints...

This thesis presents research into the construction of persistent programming systems. Much of the thesis is concerned with the design and implementation of persistent programming languages, in particular PS-algol and Napier. Both languages support machine independent vector and raster graphics data types. Napier provides an environment mechanism that enables the incremental construction and binding of programs. Napier has a powerful type system featuring parametric polymorphism and abstract data types. The machine supporting Napier, the Persistent Abstract Machine, is investigated. The machine supports an efficient implementation of parametric polymorphism and abstract data types. The Persistent Abstract Machine has a layered architecture in which permits experimentation into language implementation and store design. The construction of compilers in a persistent environment is explored. A flexible compiler architecture is developed. With it, a family of compilers may be constructed a...

In recent years a range of single programming language systems have been developed that are supported by a persistent store. Examples of such systems include Argus, Galileo, PS-algol and Smalltalk. Although each of these systems is based on a subtly different concept of persistence a common approach is to utilise a layered architecture. This paper presents the design of one such layered architecture that can be used to support a persistent object store where the protection is enforced by a high level type system. The architecture has been used to construct the persistent programming system for Napier88 and is powerful enough to support languages with similar type systems. 2 1 Introduction In recent years a range of single programming language systems have been developed that are supported by a persistent store[atk82,atk83b,ros83,bro85,that86,bro89]. Examples of such systems include Argus[lis84], Galileo[alb85a], PS-algol[psa88] and Smalltalk[gol83]. Although each of these s...

This paper describes proposed extensions to the Ada95 programming language to provide support for persistent programming. The extensions support transparent migration of data between a program's address space and a persistent store in a way that preserves both type safety and encapsulation of ADT's. 1 Introduction Ada has recently undergone an intensive and major review and update. The result of this is the new programming language Ada95 (ISO 1995) which is, in the main, backward compatible with Ada83. Two of the principle changes to Ada was the addition of appropriate semantic constructs to change Ada from an objectbased language to a fully fledged object-oriented language and the provision of annexes defining additional language capabilities for specific user communities. In this paper we consider further extensions to Ada95 by way of the introduction of a persistence annex to provide persistent programming support to Ada. We call this revision persistent Ada95 to distinguish it fr...

We identify problems in using traditional programming systems to write applications that access internet data. Some of these problems may be artefacts of current internet technology, and some are fundamental in any large heterogeneous and autonomous network. Our experimental approach to this is to design a new language system, with a semantic domain which corresponds, as far as possible, to that of the problem domain. Our primary aim is to allow the straightforward automation of tasks currently performed in a routine way by human beings interacting with Web browsers, in terms accessible to programmers who are not necessarily expert in the underlying protocols and mechanisms. In this paper we describe a system which has been designed and implemented as a first experimental step along this path. We believe we have identified some simplifying concepts, and through early experiments have gained some experience in both their use and implementation. This is very much a position paper, since...

. Research into persistent programming languages and systems in recent years has shown that the technology is useful for developing complex software in many problem domains. This paper explores the issues and consequences of adding persistence to Ada95. The persistence extensions support transparent migration of objects between a program's address space and a persistent store in a way that preserves both type safety and encapsulation of abstract data types. Keywords and Phrases: Kinds of systems: persistent systems; Ada95; object-oriented technology. 1 Introduction Ada has recently undergone an intensive and major review and update. The result of this is the new programming language Ada95[23] which is, in the main, backward compatible with Ada83[36]. Two of the principle changes to Ada were the addition of new constructs to change it from an object-based language to a fully fledged object-oriented language and the provision of annexes defining additional language capabilities for spec...

I declare that this thesis has been composed by myself and that the research reported therein has been conducted by myself unless otherwise indicated.