Feature-Oriented Software Development (FOSD) provides a multitude of formalisms, methods, languages, and tools for building variable, customizable, and extensible software. Along different lines of research different ideas of what a feature is have been developed. Although the existing approaches have similar goals, their representations and formalizations have not been integrated so far into a common framework. We present a feature algebra as a foundation of FOSD. The algebra captures the key ideas and provides a common ground for current and future research in this field, in which also alternative options can be explored.

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

Feature modeling is a notation and an approach for modeling commonality and variability in product families. In their basic form, feature models contain mandatory/optional features, feature groups, and implies and excludes relationships. It is known that such feature models can be translated into propositional formulas, which enables the analysis and configuration using existing logicbased tools. In this paper, we consider the opposite translation problem, that is, the extraction of feature models from propositional formulas. We give an automatic and efficient procedure for computing a feature model from a formula. As a side effect we characterize a class of logical formulas equivalent to feature models and identify logical structures corresponding to their syntactic elements. While many different feature models can be extracted from a single formula, the computed model strives to expose graphically the maximum of the original logical structure while minimizing redundancies in the representation. The presented work furthers our understanding of the semantics of feature modeling and its relation to logics, opening avenues for new applications in reverse engineering and refactoring of feature models.

Feature-Oriented Software Development (FOSD) provides a multitude of formalisms, methods, languages, and tools for building variable, customizable, and extensible software. Along different lines of research, different notions of a feature have been developed. Although these notions have similar goals, no common basis for evaluation, comparison, and integration exists. We present a feature algebra that captures the key ideas of feature orientation and provides a common ground for current and future research in this field, in which also alternative options can be explored.

Features express the variabilities and commonalities among programs in a software product line (SPL). A feature model defines the valid combinations of features, where each combination corresponds to a program in an SPL. SPLs and their feature models evolve over time. We classify the evolution of a feature model via modifications as refactorings, specializations, generalizations, or arbitrary edits. We present an algorithm to reason about feature model edits to help designers determine how the program membership of an SPL has changed. Our algorithm takes two feature models as input (before and after edit versions), where the set of features in both models are not necessarily the same, and it automatically computes the change classification. Our algorithm is able to give examples of added or deleted products and efficiently classifies edits to even large models that have thousands of features. 1

Feature-Oriented Software Development provides a multitude of formalisms, methods, languages, and tools for building variable, customizable, and extensible software. Along different lines of research, different notions of a feature have been developed. Although these notions have similar goals, no common basis for evaluation, comparison, and integration exists. We present a feature algebra that captures the key ideas of feature orientation and that provides a common ground for current and future research in this field, on which also alternative options can be explored. Furthermore, our algebraic framework is meant to serve as a basis for the development of the technology of automatic feature-based program synthesis and architectural metaprogramming.

Abstract. Feature Models (FMs) are a key artifact for variability and commonality management in Software Product Lines (SPLs). In this context, the merging of FMs is being recognized as an important operation to support the adoption and evolution of SPLs. However, providing automated support for merging FMs still remains an open challenge. In this paper, we propose using graph transformations as a suitable technology and associated formalism to automate the merging of FMs. In particular, we first present a catalogue of technology-independent visual rules to describe how to merge FMs. Next, we propose a prototype implementation of our catalogue using the AGG system. Finally, we show the feasibility of our proposal by means of a running example inspired by the mobile phone industry. To the best of our knowledge, this is the first approach providing automated support for merging FMs including feature attributes and cross-tree constraints. 1

Product Line Engineering (PLE) is an increasingly important paradigm in software development whereby commonalities and variations among similar systems are systematically identified and exploited. PLE covers a large spectrum of activities, from domain analysis to product validation and testing. Variability is manifested throughout this spectrum in artefacts such as models, requirements, code and components and it is often of crosscutting nature. These characteristics make Aspect-Oriented Software Development (AOSD) techniques appealing as suitable candidates to modularize variability. Work on Generative Programming (GP) and Component Engineering (CE) has shown the crucial role they play in PLE and the potential

Abstract: A multi-agent system product line (MAS-PL) defines an architecture whose design and implementation is accomplished using software agents to address its common and variable features. MAS-PL promotes the large-scale reuse of common and variable agency features across multiple MAS applications. The development of MAS-PLs can be achieved through MAS-specific platforms and implementation techniques, such as conditional compilation and aspect-oriented programming (AOP). However, there is not much evidence on how these techniques provide better modularity, allowing the conception of stable MAS-PL designs. This paper presents a quantitative study on the design modularity and stability of an evolving MAS-PL. The MAS-PL was built following the reactive product line adoption approach. The product line was developed and evolved based on several versions of a conference management webbased system, named Expert Committee (EC). Our evaluation is made through a series of change scenarios related to new agency features, which are agent characteristics that enhance the system with autonomous behavior. The quantitative study consists of a systematic comparison between two different versions of the EC MAS-PL based on a MAS-specific platform, called JADE. One version was implemented with object-oriented and conditional

Apart from adoption strategies, an existing Software Product Line (SPL) implemented using some variability mechanisms can be migrated to use another variability mechanism. In this paper, we present some migration strategies from one SPL implemented with conditional compilation to one using Aspect-Oriented Programming (AOP). The strategies present a variability pattern handled by the first mechanism and shows how it can be translated into a pattern using AOP constructs. We also show and discuss that some variability patterns cannot be migrated into AOP. The discussion centers around a commercial SPL in the mobile games domain. 1.