We present Jiazzi, a system that enables the construction of largescale binary components in Java. Jiazzi components can be thought of as generalizations of Java packages with added support for external linking and separate compilation. Jiazzi components are practical because they are constructed out of standard Java source code. Jiazzi requires neither extensions to the Java language nor special conventions for writing Java source code that will go inside a component. Our components are expressive because Jiazzi supports cyclic component linking and mixins, which are used together in an open class pattern that enables the modular addition of new features to existing classes. This paper describes Jiazzi, how it enhances Java with components, its implementation, and how type checking works. An implementation of Jiazzi is available for download.

It has been recognized in several works that a slice of behavior affecting a set of collaborating classes is a better unit of reuse than a single class. Different techniques and language extensions have been suggested to express such slices in programming languages. We propose delegation layers, an approach that scales the OO mechanisms for single objects, such as delegation, late binding, and subtype polymorphism, to sets of collaborating objects. Technically, delegation layers combine and generalize delegation and virtual class concepts. Due to their runtime semantics, delegation layers are more flexible than previous compile time approaches like mixin layers.

Abstract. This paper presents FeatureC++, a novel language extension to C++ that supports Feature-Oriented Programming (FOP) and Aspect-Oriented Programming (AOP). Besides well-known concepts of FOP languages, FeatureC++ contributes several novel FOP language features, in particular multiple inheritance and templates for generic programming. Furthermore, FeatureC++ solves several problems regarding incremental software development by adopting AOP concepts. Starting our considerations on solving these problems, we give a summary of drawbacks and weaknesses of current FOP languages in expressing incremental refinements. Specifically, we outline five key problems and present three approaches to solve them: Multi Mixins, Aspectual Mixin Layers, and Aspectual Mixins that adopt AOP concepts in different ways. We use FeatureC++ as a representative FOP language to explain these three approaches. Finally, we present a case study to clarify the benefits of FeatureC++ and its AOP extensions. 1

Two programming paradigms are gaining attention in the overlapping fields of software product lines (SPLs) and incremental software development (ISD). Feature-oriented programming (FOP) aims at large-scale compositional programming and feature modularity in SPLs using ISD. Aspect-oriented programming (AOP) focuses on the modularization of crosscutting concerns in complex software. Although feature modules, the main abstraction mechanisms of FOP, perform well in implementing large-scale software building blocks, they are incapable of modularizing certain kinds of crosscutting concerns. This weakness is exactly the strength of aspects, the main abstraction mechanisms of AOP. We contribute a systematic evaluation and comparison of FOP and AOP. It reveals that aspects and feature modules are complementary techniques. Consequently, we propose the symbiosis of FOP and AOP and aspectual feature modules (AFMs), a programming technique that integrates feature modules and aspects. We provide a set of tools that support implementing AFMs on top of Java and C++. We apply AFMs to a nontrivial case study demonstrating their practical applicability and to justify our design choices.

Current general-purpose memory allocators do not provide sufficient speed or flexibility for modern high-performance applications. Highly-tuned general purpose allocators have per-operation costs around one hundred cycles, while the cost of an operation in a custom memory allocator can be just a handful of cycles. To achieve high performance, programmers often write custom memory allocators from scratch -- a difficult and error-prone process. In this

Abstract. Superimposition is a composition technique that has been applied successfully in several areas of software development. In order to unify several languages and tools that rely on superimposition, we present an underlying language-independent model that is based on feature structure trees (FSTs). Furthermore, we offer a tool, called FST-Composer, that composes software components represented by FSTs. Currently, the tool supports the composition of components written in Java, Jak, XML, and plain text. Three nontrivial case studies demonstrate the practicality of our approach. 1

We present aspect-oriented programming in Jiazzi. Jiazzi enhances Java with separately compiled, externally-linked code modules called units. Besides making programming in Java generally more modular, units are also effective "aspect" constructs that can separate concerns. The unit-linking metaphor provides a convenient and explicit way for programmers to explicitly control the inclusion and configuration of code that implements a concern, while separate compilation of units enhances concern independent development and deployment. The expressiveness of concern separation are enhanced by units in two ways. First, classes can be made open to the addition of new fields and methods by multiple units, which enables the direct modularization of concerns that crosscut objects. Second, the signatures of methods and classes used in a unit can be made open to refinement by other units, which makes it easier to integrate concern implementations by isolating them from the naming and calling requirements of shared methods and classes.

To my wife and family.

Software product lines (SPLs) are used to create tailor-made software products by managing and composing reusable assets. Generating a software product from the assets of an SPL is possible statically before runtime or dynamically at load-time or runtime. Both approaches have benefits and drawbacks with respect to composition flexibility, performance, and resource consumption. Which type of composition is preferable should be decided by taking the application scenario into account. Current tools and languages, however, force a programmer to decide between static and dynamic composition during development. In this paper, we present an approach that employs code generation to support static and dynamic composition of features of a single code base. We offer an implementation on top of FeatureC++, an extension of the C++ programming language that supports software composition based on features. To simplify dynamic composition and to avoid creation of invalid products we furthermore provide means to (1) validate the correctness of a composition at runtime, (2) automatically instantiate SPLs in case of stand-alone applications, and (3) automatically apply interaction code of crosscutting concerns.

Current publish/subscribe middleware infrastructures fall short of mechanisms that allow their customization and configuration to comply with the requirements of different application domains. This shortcoming is a consequence of their original design which does not account for mechanisms or approaches that allow the evolution of this kind of services. This survey introduces the concept of versatility in publish/subscribe infrastructures and examines the current approaches to versatility in publish-subscribe middleware as well as approaches to versatility that have been applied in other kinds of middleware and may possibly succeed in the context of publish/subscribe infrastructures. In this context, versatility is defined as a set of properties (such as variability, reuse, dynamism and usability) that allows the customization, extension and compression of middleware. This paper surveys existing and advanced software engineering approaches to address those requirements. A comparative framework on software versatility, as a set of properties, is presented to help researches and practitioners to evaluate and compare the strengths and limitations of such approaches that have been or might be applied to this