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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 at relatively little cost. One such compiler is the callable compiler; this is a first class data object in the persistent environment. The uses of such a compiler are explored, in particular in the construction of an object browser. The persistent object browser introduces a new software architecture that permits adaptive programs to be constructed incrementally. This is achieved by writing, compiling and linking new procedures into an executing program. The architecture has been successfully applied to the construction of adaptive databases and bootstrap compilers.

The design and development of a type secure persistent object store is presented as part of an architecture to support experiments in concurrency, transactions and distribution. The persistence abstraction hides the physical properties of data from the programs that manipulate it. Consequently, a persistent object store is required to be of unbounded size, infinitely fast and totally reliable. A range of architectural mechanisms that can be used to simulate these three features is presented. Based on a suitable selection of these mechanisms, two persistent object stores are presented. The first store is designed for use with the programming language PS-algol. Its design is evolved to yield a more flexible layered architecture. The layered architecture is designed to provide each distinct architectural mechanism as a separate architectural layer conforming to a specified interface. The motivation for this design is two-fold. Firstly, the particular choice of layers greatly simplifies the resulting implementation and secondly, the layered design can support experimental architecture implementations. Since each layer conforms to a specified interface, it is possible to experiment with the implementation of an individual layer without affecting the implementation of the remaining architectural layers. Thus, the layered architecture is a convenient vehicle for experimenting with the implementation of persistent object stores. An implementation of the layered architecture is presented together with an example of how it may be used to support a distributed system. Finally, the architecture's ability to support a variety of storage configurations is presented.

Packet communications have increasingly become popular since the launch of the first ever packet-switched network, the ARPANET. Evolution of such networks resulted in creation of the Internet, the global packet-switched network. Amongst the well-known advantages of packet-switching are service transparency, cost-effectiveness, and high system capacity. A natural pathway will incorporate tetherless mobility features to packet services. The key component to realisation of wireless packet communication is the multiple access technology (the subject of this thesis), capable of optimum sharing of scarce radio resources amongst a diverse set of packetized information sources. Based on core features of packet multiple access protocols, a classification is presented by which most proposed protocols could be mapped into. For mixed services, two equivalent offered loads, namely ''access load" and "traffic load", are derived. The former can be used for design, optimisation, and stabilisation of the access mechanism, whilst the latter is to evaluate the overall system performance. The proposed normalised offered loads are found accurate and instrumental in predicting and designing packet access protocols for mixed services. "Statistical upper-bounds" for packet access protocols are derived (both for random access and general access mechanisms), based on which an "efficiency factor" is defined to evaluate and compare merits of protocols against each other. Conventionally, analysis of resource-sharing systems with mixed services (such as multiple access protocols) involve multidimensional Markov chains which become quite intractable for more than two service types. In order to avoid multidimensional Markov analysis, an analytical method called "Aggregate Source Modelling" is proposed by means of which various service types are aggregated into a representative service type. The proposed method is deployed to analyse various queueing and multiple access scenarios. Finally, a series of multiple access protocols are presented for adapting real-time and non-real-time packet services to existing cellular and satellite systems. For evaluation purposes, the proposed statistical models of packet services (such as FTP, E- mail, WWW, packet voice, and so forth) are used throughout the thesis. These models have components of various statistical distributions, namely, Poisson (Exponential), lognormal, Pareto, Cauchy, Gaussian, Geometric, and Hyper-Exponential. Extensive discrete-time simulation models have been developed for evaluation purposes.

Software Engineering progresses as improvements are made in languages and methodologies. Significant advances have been made through the use of Object- Oriented Programming, exploiting the effective support available in C++. Further evolution of OOP involving the use of design patterns and aspects requires additional language support. Increased flexibility in the declaration of objects is proposed in the form of the FOG (Flexible Object Generator) language, which is a superset of C++ implemented by a translator to C++. FOG generalises C++ syntax and supports compile-time meta-programming and reflection. The syntax generalisations provide the freedom for programmers to organise code to suit programming concerns and eliminate the need for duplication between interfaces and implementations. Further generalisations define composition policies for repeated declarations so that classes, arrays, enumerations and functions may all be extended. These composition policies support the weaving necessary for re-useable implementation of design patterns and for Aspect Oriented Programming. A declarative form of meta-programming is supported by derivation rules, which specify how a declaration specified in a base class is to be reinterpreted in derived classes. Automated generation of derived functionality is important for a number of design patterns. More general meta-programming is provided by elevating most run-time concepts to the meta-level, allowing conditional and iterated manipulation of declarations at compile-time. Compile-time execution enables subsequent run-time code to be optimised to suit application requirements. The use of meta-variables and meta-functions together with a well-disciplined lexical context for meta-programming and meta-level execution provide a complete replacement for the traditional C preprocessor functionality, satisfying Stroustrup's goal of making Cpp redundant [Stroustrup97]. The new functionality is integrated with the language, fits within an Object-Oriented framework and provides adequate support for modern Software Engineering practices. The C++ grammar is known to pose a significant parsing challenge and to require context dependent type and template knowledge. This creates considerable difficulties when meta-programming occurs in unresolved contexts. A new approach to parsing C++ has therefore been developed that defers the use of type and template information. This approach leads to a simpler grammar implementation. An extended form of regular expression is presented and used to predict known ambiguities and then show that this simpler grammar covers the C++ grammar.

A generic visual language for diagram editing has been created which may be instantiated for a particular modelling technique. The instantiated visual language is used within the generated design tool. It provides non-obtrusive guidance observing the semantics of the underlying modelling technique. The tool user is allowed to produce intermediate inconsistent states to facilitate diagram editing. A prototype, comprising a compiler for the specification language, a multi-purpose graph tool and a configurable design tool was implemented to prove the feasibility of the complete approach. The prototype compiler generates executable code. The target of the compiler is the persistent programming language Napier88. The architecture of the compiler has been designed as two separate components: a front-end (the parser), and a back-end (the code generator). This approach gives independence from the target language. The code generator comprises a number of translation rules to produce Napier88 from a VC-t specification. The prototype compiler only incorporates some of the translation rules to demonstrate that executable Napier88 can be generated automatically. The remainder of the translation rules have been applied manually to produce Napier88, to demonstrate that the rules are correct. The multi-purpose graph tool, designated as GraphTool, can be used with the class of applications using graphs as their main data structures. It provides support for visual and interactive representations of an application. The application acts as a client of the Graph-Tool. A protocol has been defined to connect the client application to the GraphTool. Any number of visual representations can be associated with the application. Maps are used for this purpose: to change the representation it is only necessary to change the map. The GraphTool includes a constraint manager used to associate constraints with the representations objects and check these at run-time. The configurable design tool has been developed as a client for the GraphTool. It includes generic components for diagram editing and a drawing canvas. The functionality of the canvas is fully provided by the GraphTool.

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