There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality.

Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

I and i

Deposits of clastic carbonate-dominated (calciclastic) sedimentary slope systems in the rock record have been identified mostly as linearly-consistent carbonate apron deposits, even though most ancient clastic carbonate slope deposits fit the submarine fan systems better. Calciclastic submarine fans are consequently rarely described and are poorly understood. Subsequently, very little is known especially in mud-dominated calciclastic submarine fan systems. Presented in this study are a sedimentological core and petrographic characterisation of samples from eleven boreholes from the Lower Carboniferous of Bowland Basin (Northwest England) that reveals a >250 m thick calciturbidite complex deposited in a calciclastic submarine fan setting. Seven facies are recognised from core and thin section characterisation and are grouped into three carbonate turbidite sequences. They include: 1) Calciturbidites, comprising mostly of highto low-density, wavy-laminated bioclast-rich facies; 2) low-density densite mudstones which are characterised by planar laminated and unlaminated muddominated facies; and 3) Calcidebrites which are muddy or hyper-concentrated debrisflow deposits occurring as poorly-sorted, chaotic, mud-supported floatstones. These

Phd by thesis

Aspect] is a simple and practical aspect-oriented extension to Java With just a few new constructs, AspectJ provides support for modular implementation of a range of crosscutting concerns. In AspectJ's dynamic join point model, join points are well-defined points in the execution of the program; pointcuts are collections of join points; advice are special method-like constructs that can be attached to pointcuts; and aspects are modular units of crosscutting implementation, comprising pointcuts, advice, and ordinary Java member declarations. AspectJ code is compiled into standard Java bytecode. Simple extensions to existing Java development environments make it possible to browse the crosscutting structure of aspects in the same kind of way as one browses the inheritance structure of classes. Several examples show that AspectJ is powerful, and that programs written using it are easy to understand.

An overview of AspectJ

The goal of this roadmap paper is to summarize the state-of-the-art and to identify critical challenges for the systematic software engineering of self-adaptive systems. The paper is partitioned into four parts, one for each of the identified essential views of self-adaptation: modelling dimensions, requirements, engineering, and assurances. For each view, we present the state-of-the-art and the challenges that our community must address. This roadmap paper is a result of the Dagstuhl Seminar 08031 on "Software Engineering for Self-Adaptive Systems," which took place in January 2008.

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Software Engineering for Self-Adaptive Systems: A Research Roadmap

Several module and class testing techniques have been applied to object-oriented (OO) programs, but researchers have only recently begun developing test criteria that evaluate the use of key OO features such as inheritance, polymorphism, and encapsulation. Mutation testing is a powerful testing technique for generating software tests and evaluating the quality of software. However, the cost of mutation testing has traditionally been so high that it cannot be applied without full automated tool support. This paper presents a method to reduce the execution cost of mutation testing for OO programs by using two key technologies, mutant schemata generation (MSG) and bytecode translation. This method adapts the existing MSG method for mutants that change the program behaviour and uses bytecode translation for mutants that change the program structure. A key advantage is in performance: only two compilations are required and both the compilation and execution time for each is greatly reduced. A mutation tool based on the MSG/bytecode translation method has been built and used to measure the speedup over the separate compilation approach. Experimental results show that the MSG/bytecode translation method is about five times faster than separate compilation. Copyright © 2004 John Wiley & Sons, Ltd.

/pdf/mujava-an-automated-class-mutation-system-2ws1jr6s2i.pdf

MuJava: an automated class mutation system

Context-dependent behavior is becoming increasingly important for a wide range of application domains, from pervasive computing to common business applications. Unfortunately, mainstream programming languages do not provide mechanisms that enable software entities to adapt their behavior dynamically to the current execution context. This leads developers to adopt convoluted designs to achieve the necessary runtime exibility. We propose a new programming technique called Context-oriented Programming (COP) which addresses this problem. COP treats context explicitly, and provides mechanisms to dynamically adapt behavior in reaction to changes in context, even after system deployment at runtime. In this paper, we lay the foundations of COP, show how dynamic layer activation enables multi-dimensional dispatch, illustrate the application of COP by examples in several language extensions, and demonstrate that COP is largely independent of other commitments to programming style.

/pdf/context-oriented-programming-1f235jecqp.pdf

Context-oriented Programming

ContextL is an extension to the Common Lisp Object System that allows for Context-oriented Programming. It provides means to associate partial class and method definitions with layers and to activate and deactivate such layers in the control flow of a running program. When a layer is activated, the partial definitions become part of the program until this layer is deactivated. This has the effect that the behavior of a program can be modified according to the context of its use without the need to mention such context dependencies in the affected base program. We illustrate these ideas by providing different UI views on the same object while, at the same time, keeping the conceptual simplicity of object-oriented programming that objects know by themselves how to behave, in our case how to display themselves. These seemingly contradictory goals can be achieved by separating class definitions into distinct layers instead of factoring out the display code into different classes.

/pdf/language-constructs-for-context-oriented-programming-an-2ihhs0jbd5.pdf

Language constructs for context-oriented programming: an overview of ContextL

Current proposals for load-time transformation of Java classes are either dependent on the use of a specific class loader or dependent on a specific JVM implementation. This is not due to an inadequacy of the Java platform but to the wrong choice of the level at which to hook into the Java Class Loader Architecture. JMangler follows a novel approach that ensures both class loader and JVM independence by hooking into the base class of all class loaders. Furthermore, existing proposals do not allow transformers to be treated as components because implicit dependencies must be resolved manually. The paper shows that automatic composition is possible for the well-defined class of interface transformations that still include powerful transformations, like addition of fields, methods and classes, and changes to the class hierarchy. Consequently, interface transformers can be deployed jointly even if developed independently.

/pdf/jmangler-a-framework-for-load-time-transformation-of-java-1vgcmb1k57.pdf

JMangler - a framework for load-time transformation of Java class files

Today’s programming platforms do not provide sufficient constructs that allow a program’s behavior to depend on the context in which it is executing. This paper presents the design and implementation of programming language extensions that explicitly support our vision of Context-oriented Programming. In this model, programs can be partitioned into layers that can be dynamically activated and deactivated depending on their execution context. Layers are sets of partial program definitions that can be composed in any order. Context-oriented Programming encourages rich, dynamic modifications of program behavior at runtime, requiring an efficient implementation. We present a dynamic representation of layers that yields competitive performance characteristics for both layer activation/deactivation and overall program execution. We illustrate the performance of our implementation by providing an alternative solution for one of the prominent examples of aspect-oriented programming.

/pdf/efficient-layer-activation-for-switching-context-dependent-460uwighqs.pdf

Efficient layer activation for switching context-dependent behavior

Context-oriented Programming, or COP, provides programmers with dedicated abstractions and mechanisms to concisely represent behavioral variations that depend on execution context. By treating context explicitly, and by directly supporting dynamic composition, COP allows programmers to better express software entities that adapt their behavior late-bound at run-time. Our paper illustrates COP constructs, their application, and their implementation by developing a sample scenario, using ContextS in the Squeak/Smalltalk programming environment.

/pdf/an-introduction-to-context-oriented-programming-with-2lkoyi60gm.pdf

Pascal Costanza

Papers

Context-oriented Programming

Language constructs for context-oriented programming: an overview of ContextL

JMangler - a framework for load-time transformation of Java class files

Efficient layer activation for switching context-dependent behavior

An Introduction to Context-Oriented Programming with ContextS