Layered, server-based support for Object-Oriented application development

Journal ArticleThis paper advocates the idea that the physical modularity (file structure) of application components supported by conventional OS environments can be elevated to the level of logical modularity, which in turn can directly support application development in an object-oriented manner. We demonstrate this idea through a system-wide server process that manages a separate logical layer of components. The server is designed to be a central operating system service responsible for mapping component instances into client address spaces. We show how this model solves some longstanding problems with the management and binding of application components in existing operating system environments. We illustrate with examples that this model's effectiveness derives from its support for the cornerstones of 0-0 programming: classes and their instances, encapsulation, and several forms of inheritance

Type-safe composition of object modules

Journal ArticleWe describe a facility that enables routine type-checking during the linkage of external declarations and definitions of separately compiled programs in ANSI C. The primary advantage of our server-style type-checked linkage facility is the ability to program the combination of object modules via a suite of strongly typed module operators. Such programmability enables one to easily incorporate programmer-defined data format conversion stubs at link-time. In addition, our linkage facility is able to automatically generate safe coercion stubs for compatible encapsulated data.

Modular language processors as framework completions

Journal ArticleThe conceptual and specificational power of denotational semantics for programming language design has been amply demonstrated. We report here on a language implementation method that is similarly semantically motivated, but is based upon object-oriented design principles, and results in flexible and evolvable language processors. We apply this technique to the area of object-oriented (O-O) languages, in the form of a general metalevel architecture for objects and inheritance that facilitates the development of compilers and interpreters for 0-0 languages. This development strategy maintains architectural modularity by mapping conceptual language design decisions to isolatable parts of resulting language processors. Our architecture, which is presented as an OO framework, is characterized by (i) support for a broad set of modularity features including encapsulation and strong typing, and (ii) an "unbundled" view of inheritance, semantic features of which are decomposed by means of a set of module combination operations (combinators). We describe an implementation of our framework in C++, and assess its utility by constructing a compiler for a simple 0 - 0 extension to the programming language C. We further argue the flexibility of the resulting processor by outlining the incorporation of several significant extensions to the basic module language. We claim that the use of such a framework for compiler construction has many advantages, including a systematic language development method, processor software reuse, language extensibility, and potential for interoperability among languages.

ETYMA: a framework for modular systems

Journal ArticleModularity, i.e. support for the flexible construction, adaptation, and combination of units of software, is an important goal in many systems. In most cases, however, systems achieve only a few aspects of modularity. The problem can be traced to the inflexibility, or the limited view of modularity taken by the underlying architecture of these systems. As a remedy, we show that the notions fundamental to object-oriented programming, i.e. classes and inheritance, can be formulated as a simple meta-level architecture that can be effectively reused in a wide variety of contexts. We have realized such an architecture as an O-O framework, and constructed two significant and distinct completions of it. Systems based on this framework benefit not only from design and code reuse, but also from the flexibility that the architecture offers. In addition, the architecture represents a unification of the fundamental ideas of several similar but subtly different module systems

Gryphon: An Information Flow Based Approach to Message Brokering

Gryphon is a distributed computing paradigm for message brokering, which is the transferring of information in the form of streams of events from information providers to information consumers. This extended abstract outlines the major problems in message brokering and Gryphon's approach to solving them.Comment: Two page extended abstrac

An Application Framework For Compositional Modularity

This dissertation presents a framework for the application of compositional modularity, a module model that facilitates extensive reuse of highly decomposed software. Compositional modularity supports not only the traditional notions of program decomposition and encapsulation but also effective mechanisms for module recomposition. Based on a previously developed model, a suite of operators individually achieve effects of adaptation and combination on a simple notion of modules viewed as self-referential namespaces. This dissertation extends the previous model by introducing the notion of hierarchical nesting as a composition operation. Furthermore, this work shows that compositional modularity is unifying in scope. Important effects and idioms of advanced modularity, including several varieties of inheritance in object-oriented programming, find convenient expression within this model. Compositional modularity can be applied within a wide range of systems that manipulate self-referenti..