We have found many programming problems for which neither procedural nor object-oriented programming techniques are sufficient to clearly capture some of the important design decisions the program must implement. This forces the implementation of those design decisions to be scattered throughout the code, resulting in “tangled” code that is excessively difficult to develop and maintain. We present an analysis of why certain design decisions have been so difficult to clearly capture in actual code. We call the properties these decisions address aspects, and show that the reason they have been hard to capture is that they crosscut the system’s basic functionality. We present the basis for a new programming technique, called aspect-oriented programming, that makes it possible to clearly express programs involving such aspects, including appropriate isolation, composition and reuse of the aspect code. The discussion is rooted in systems we have built using aspect-oriented programming.

This paper presents a metaobject protocol (MOP) for C++. This MOP was designed to bring the power of meta-programming to C++ programmers. It avoids penalties on runtime performance by adopting a new meta-architecture in which the metaobjects control the compilation of programs instead of being active during program execution. This allows the MOP to be used to implement libraries of efficient, transparent language extensions.

This paper proposes an approach to the design of configurable and open middleware platforms based on the concept of reflection. More specifically, the paper introduces a language-independent reflective architecture featuring a perobject meta-space, the use of meta-models to structure meta-space, and a consistent use of object graphs for composite components. This is complemented by a component framework supporting the construction of meta-spaces. The paper also reports on experiences of implementing the architecture (with emphasis on experiments with open bindings). Keywords Middleware, (re-)configuration, reflection, open implementation, open bindings. 1 INTRODUCTION Middleware has emerged as an important architectural component in supporting distributed applications. The role of middleware is to present a unified programming model to application writers and to mask out problems of heterogeneity and distribution. The importance of the topic is reflected in the increasing visibili...

This paper presents a methodology for designing extensible languages for distributed computing.

This article presents the design principles and efficient implementation techniques for ABCL/R3, an object-oriented concurrent reflective language. One of the most distinguished features of ABCL/R3 is compilation techniques using partial evaluation, which effectively remove interpretation from meta-level programs. The meta-level objects are designed so that they can be partially evaluated in an effective manner. Benchmark programs show that our compilation frameworks make object execution drastically faster than interpreter-based implementations, and achieves performance close to nonreflective compilers.

this paper we consider remote creation, migration, and reachability snapshot services: their specification at different levels of abstraction, and their composition. 1.1 About Actors

. In distributed environments, location control of objects among hosts is a crucial concern. This paper proposes a new mechanism of object location control using meta-level programming which provides the following advantages to programmers. First, the description of location control can be separated from the application program by exploiting the meta-level architecture. This separation makes it easy for programmers to understand application programs and change location control policies. Second, it is possible for programmers to control object location using runtime information provided at the meta-level such as the number of remote messages. This information enables programmers to control object location more flexibly than in traditional distributed languages. The mechanism proposed in this paper has been implemented on an AL-1/D distributed reflective programming system. We show that our mechanism of location control using meta-level programming provides reasonable perfo...

The very success and breadth of reflective techniques underscores the need for a general theory of reflection. At present what we have is a wide-ranging variety of reflective systems, each explained in its own idiosyncratic terms. Metalogical foundations can allow us to capture the essential aspects of reflective systems in a formalismindependent way. This paper proposes metalogical axioms for reflective logics and declarative languages based on the theory of general logics [34]. In this way, several strands of work in reflection, including functional, equational, Horn logic, and rewriting logic reflective languages, as well as a variety of reflective theorem proving systems are placed within a common theoretical framework. General axioms for computational strategies, and for the internalization of those strategies in a reflective logic are also given. 1 Introduction Reflection is a fundamental idea. In logic it has been vigorously pursued by many researchers since the fundamental wor...

Meta-level programmability is beneficial for parallel /distributed object-oriented computing to improve performance, etc. The major problem, however, is interpretation overhead due to meta-circular interpretation. To solve this problem, we propose a compilation framework for object-oriented concurrent reflective languages using partial evaluation. Since traditional partial evaluators do not allow us to directly deal with meta-circular interpreters written with concurrent objects, we devised techniques such as pre-/post-processing, a new proposed preaction extension to partial evaluation in order to handle side-effects, etc. Benchmarks of a prototype compiler for our language ABCL/R3 indicate that (1) the meta-level interpretation is essentially `compiled away,' and (2) meta-level optimizations in a parallel application, running on a Fujitsu MPP AP1000, exhibits only 10--30% overhead compared to the hand-crafted source-level optimization in a non-reflective language. 1 Introduction In...

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