Семантически-ориентированная миграция Java-программ: опыт практического применения

The purpose of the study is to demonstrate the feasibility of automated code migration to a new set of programming libraries. Code migration is a common task in modern software projects. For example, it may arise when a project should be ported to a more secure or feature-rich library, a new platform or a new version of an already used library. The developed method and tool are based on the previously created by the authors a formalism for describing libraries semantics. The formalism specifies a library behaviour by using a system of extended finite state machines (EFSM). This paper outlines the metamodel designed to specify library descriptions and proposes an easy to use domainspecific language (DSL), which can be used to define models for particular libraries. The mentioned metamodel directly forms the code migration procedure. A process of migration is split into five steps, and each step is also described in the paper. The procedure uses an algorithm based on the breadth- first search extended for the needs of the migration task. Models and algorithms were implemented in the prototype of an automated code migration tool. The prototype was tested by both artificial code examples and a real-world open source project. The article describes the experiments performed, the difficulties that have arisen in the process of migration of test samples, and how they are solved in the proposed procedure. The results of experiments indicate that code migration can be successfully automated. Данная статья посвящена разработке процедуры автоматизированной миграции Java-программ на новый набор библиотек. Задача миграции (портирования) кода часто встречается в современных программных проектах. Например, такая задача может возникнуть, когда проект необходимо перенести на более безопасную или функциональную библиотеку, на новую платформу или на новую версию уже используемой в проекте библиотеки. В данной работе представлена процедура автоматизированной миграции, основанная на семантическом подходе. Для процедуры миграции была разработана метамодель библиотеки, использующая предложенный ранее авторами формализм и предназначенная для описания библиотек на объектно-ориентированных языках. Формализм описывает поведение библиотек с помощью системы расширенных конечных автоматов (РКА). Процедура миграции разбита на пять шагов, каждый шаг подробно описан в тексте статьи. В процедуре используется алгоритм вычисления эквивалентной трассы на основе поиска в ширину, расширенный для решения задач миграции. Предложенная процедура реализована в прототипе инструмента миграции. Инструмент включает в себя модули извлечения трассы выполнения программ, визуализации моделей библиотек, взаимодействия с пользователем и непосредственно миграции. Для инструмента был разработан язык описания библиотек. Прототип инструмента был протестирован как на искусственных примерах, так и на существующем проекте. В статье подробно описаны проведенные эксперименты, отдельно отмечены сложности, возникающие в процессе миграции тестовых примеров, и то, как они решаются в предложенной процедуре. В качестве библиотек в экспериментах используются реализации протокола HTTP и библиотеки протоколирования. Результаты тестирования показали, что миграция кода может быть успешно автоматизирована с использованием разработанной процедуры.

Code Smells and Refactoring: A Tertiary Systematic Review of Challenges and Observations

In this paper, we present a tertiary systematic literature review of previous surveys, secondary systematic literature reviews, and systematic mappings. We identify the main observations (what we know) and challenges (what we do not know) on code smells and refactoring. We show that code smells and refactoring have a strong relationship with quality attributes, i.e., with understandability, maintainability, testability, complexity, functionality, and reusability. We argue that code smells and refactoring could be considered as the two faces of a same coin. Besides, we identify how refactoring affects quality attributes, more than code smells. We also discuss the implications of this work for practitioners, researchers, and instructors. We identify 13 open issues that could guide future research work. Thus, we want to highlight the gap between code smells and refactoring in the current state of software-engineering research. We wish that this work could help the software-engineering research community in collaborating on future work on code smells and refactoring

Using Clustering Techniques to Guide Refactoring of Object-Oriented Classes

Much of the cost of software development is maintenance. Well structured software tends to be cheaper to maintain than poorly structured software, because it is easier to analyze and modify. The research described in this thesis concentrates on determining how to improve the structure of object-oriented classes, the fundamental unit of organization for object-oriented programs. Some refactoring tools can mechanically restructure object-oriented classes, given the appropriate inputs regarding what attributes and methods belong in the revised classes. We address the research question of determining what belongs in those classes, i.e., determining which methods and attributes most belong together and how those methods and attributes can be organized into classes. Clustering techniques can be useful for grouping entities that belong together; however, doing so requires matching an appropriate algorithm to the domain task and choosing appropriate inputs. This thesis identifies clustering techniques suitable for determining the redistribution of existing attributes and methods among object-oriented classes, and discusses the strengths and weaknesses of these techniques. It then describes experiments using these techniques as the basis for refactoring open source Java classes and the changes in the class quality metrics that resulted. Based on these results and on others reported in the literature, it recommends particular clustering techniques for particular refactoring problems. These clustering techniques have been incorporated into an open source refactoring tool that provides low-cost assistance to programmers maintaining object-oriented classes. Such maintenance can reduce the total cost of software development