Towards Improving Interface Modularity in Legacy Java Software through Automated Refactoring

The skeletal implementation pattern is a software design pattern consisting of defining an abstract class that provides a partial interface implementation. However, since Java allows only single class inheritance, if implementers decide to extend a skeletal implementation, they will not be allowed to extend any other class. Also, discovering the skeletal implementation may require a global analysis. Java 8 enhanced interfaces alleviate these problems by allowing interfaces to contain (default) method implementations, which implementers inherit. Java classes are then free to extend a different class, and a separate abstract class is no longer needed; developers considering implementing an interface need only examine the interface itself. We argue that both these benefits improve software modularity, and discuss our ongoing work in developing an automated refactoring tool that would assist developers in taking advantage of the enhanced interface feature for their legacy Java software

Migrating inheritance-based applications into components

Inheritance is one of the most important object-oriented mechanisms, allowing code reuse and a conceptual hierachical modelling of a given domain. However, as a white-box reuse mechanism, it introduces hidden (implicit) coupling between classes in a hierarchy. This problem makes understanding and maintenance difficult to grasp. Actual approaches (such as Gamma’s) propose object composition over class inheritance as reuse mechanism to obtain better object-oriented design. However the migration of a class-based application (or just some software artifacts) from inheritance to composition paradigms is not trivial. To our knowledge, there are only a few approaches that can deal with this problem, but there is no formal language-independent analysis of a transformation algorithm that guarantees the exact same behavior of a system once the migration strategies have been applied. Thus, this paper presents some initial results in designing a refactoring approach for a class hierarchy by analyzing the dependencies between the classes involved in the inheritance relationship in a class-based system, and how they can be transformed to obtain a better structure of the class hierarchy, focusing on getting components with offered- and required-services in component-based system. Based on this study, our main goal in this approach is to develop a (semi)automatic language-independent algorithm using refactoring-based strategies which allows the user to transform an inheritance relationship between a set of classes into an association between two independent components with well defined interfaces.Presentado en el VIII Workshop Ingeniería de Software (WIS)Red de Universidades con Carreras en Informática (RedUNCI

Identification of refused bequest code smells

Abstract-Accumulated technical debt can be alleviated by means of refactoring application aiming at architectural improvement. A prerequisite for wide scale refactoring application is the automated identification of the corresponding refactoring opportunities, or code smells. One of the major architectural problems that has received limited attention is the so called 'Refused Bequest' which refers to inappropriate use of inheritance in object-oriented systems. This code smell occurs when subclasses do not take advantage of the inherited behavior, implying that replacement by delegation should be used instead. In this paper we propose a technique for the identification of Refused Bequest code smells whose major novelty lies in the intentional introduction of errors in the inherited methods. The essence of inheritance is evaluated by exercising the system's functionality through the corresponding unit tests in order to reveal whether inherited methods are actually employed by clients. Based on the results of this approach and other structural information, an indication of the smell strength on a 'thermometer' is obtained. The proposed approach has been implemented as an Eclipse plugin

A Refactoring-Based Approach to Support Binary Backward-Compatible Framework Upgrades

Evolutionary changes applied to a framework API may invalidate existing framework-based applications. While manually adapting applications is expensive and error-prone, automatic adaptation demands cumbersome specifications, which the developers are reluctant to write and maintain. Considering structural changes (so-called refactorings) of framework APIs, our adaptation technology supports backward-compatible framework upgrade. The technology is rigorous defining precisely the structure and automatic derivation of compensating adapters. It is also practical compensating for most application-breaking API changes automatically, while requiring neither manual adaptation nor recompilation of existing application code

Improving software quality using an ontology-based approach

Ensuring quality in software development is a challenging process. The concepts of anti-pattern and bad code smells utilize the knowledge of reoccurring problems to improve the quality of current and future software development. Anti-patterns describe recurring bad design solutions while bad code smells describe source code that is error-free but difficult to understand and maintain. Code refactoring aims to remove bad code smells without changing a program’s functionality while improving program quality. There are metrics-based tools to detect a few bad code smells from source code; however, the knowledge and understanding of these indicators of low quality software are still insufficient to resolve many of the problems they represent. Minimal research addresses the relationships between or among bad code smells, anti-patterns and refactoring. In this research, we present a new ontology, Ontology for Anti-patterns, Bad Code Smells and Refactoring (OABR), to define the concepts and their relation properties. Such an ontological infrastructure encourages a common understanding of these concepts among the software community and provides more concise definitions that help to avoid overlapping and inconsistent description. It utilizes reasoning capabilities associated with ontology to analyze the software development domain and offer new insights into the domain. Software quality issues such as understandability and maintainability can be improved by identifying and resolving anti-patterns associated with code smells as well as preventing bad code smells before coding begins

Quality Assurance of Software Models - A Structured Quality Assurance Process Supported by a Flexible Tool Environment in the Eclipse Modeling Project

The paradigm of model-based software development (MBSD) has become more and more popular since it promises an increase in the efficiency and quality of software development. In this paradigm, software models play an increasingly important role and software quality and quality assurance consequently leads back to the quality and quality assurance of the involved models. The fundamental aim of this thesis is the definition of a structured syntax-oriented process for quality assurance of software models that can be adapted to project-specific and domain-specific needs. It is structured into two sub-processes: a process for the specification of project-specific model quality assurance techniques, and a process for applying them on concrete software models within a MBSD project. The approach concentrates on quality aspects to be checked on the abstract model syntax and is based on quality assurance techniques model metrics, smells, and refactorings well-known from literature. So far, these techniques are mostly considered in isolation only and therefore the proposed process integrates them in order to perform model quality assurance more systematically. Three example cases performing the process serve as proof-of-concept implementations and show its applicability, its flexibility, and hence its usefulness. Related to several issues concerning model quality assurance minor contributions of this thesis are (1) the definition of a quality model for model quality that consists of high-level quality attributes and low-level characteristics, (2) overviews on metrics, smells, and refactorings for UML class models including structured descriptions of each technique, and (3) an approach for composite model refactoring that concentrates on the specification of refactoring composition. Since manually reviewing models is time consuming and error prone, several tasks of the proposed process should consequently be automated. As a further main contribution, this thesis presents a flexible tool environment for model quality assurance which is based on the Eclipse Modeling Framework (EMF), a common open source technology in model-based software development. The tool set is part of the Eclipse Modeling Project (EMP) and belongs to the Eclipse incubation project EMF Refactor which is available under the Eclipse public license (EPL). The EMF Refactor framework supports both the model designer and the model reviewer by obtaining metrics reports, by checking for potential model deficiencies (called model smells) and by systematically restructuring models using refactorings. The functionality of EMF Refactor is integrated into standard tree-based EMF instance editors, graphical GMF-based editors as used by Papyrus UML, and textual editors provided by Xtext. Several experiments and studies show the suitability of the tools for supporting the techniques of the structured syntax-oriented model quality assurance process

Bad smells in design and design patterns

International audienceTo give a consistent and more valuable property on models, model-driven processes should be able to reuse the expert knowledge generally expressed in terms of patterns. We focus our work on the design stage and on the systematically use of design patterns. Choose a good design pattern and ensure the correct integration of the chosen pattern are non trivial for a designer who wants to use them. To help designers, we propose design inspection in order to detect “bad smells in design” and models reworking through use of design patterns. The automatic detection and the explanation of the misconceptions are performed thanks to spoiled patterns. A “spoiled pattern” is a pattern which allows to instantiate inadequate solutions for a given problem: requirements are respected, but architecture is improvable

Migration of Applications across Object-Oriented APIs

Software developers often encapsulate reusable code as Application Programming Interfaces (APIs). The co-evolution of applications and APIs may motivate an API migration: the replacement of application dependencies to an original API by dependencies to an alternative API that provides similar functionality and abstractions. In this dissertation, we investigate issues associated with API migration in object-oriented systems, with special focus on wrapping approaches. We present two studies and a set of developer interviews that elicit issues in the process and techniques used in API migration in practice. The results suggest that the most pressing issues relate to discovery and specification of differences between APIs, and to assessment of migration correctness. This dissertation introduces techniques and a method to address these issues. We propose the use of design patterns to support the specification of API wrappers. API wrapping design patterns encode solutions to common wrapping design problems. We present an initial catalog of such patterns that were abstracted from programming idioms found in existing API wrappers. We introduce the concept of compliance testing for API migration, a form of automated testing. Compliance testing supports the discovery of behavioral differences between a wrapper and its corresponding original API, as well as assessment of wrapper correctness. Compliance testing uses API contracts and assertion tunings to explicitly capture and enforce the notion of a “good enough” wrapper that is informal in practice. We present the Koloo method for wrapper-based API migration. The method prescribes practical steps to use compliance testing as a means to elicit the requirements for the API migration, and to assess its correctness. Koloo fits within the iterative, sample-driven general API migration process usually followed by developers in practice. We evaluate the Koloo method in an empirical study. The subjects cover the domains of XML processing, GUI programming and bytecode engineering. The results provide evidence that Koloo is superior to alternative methods in driving the development of a wrapper that is tailored for the application under migration. The results also show that API contracts help driving the evolution of the wrapper, and assertion tuning is necessary to relax the semantics of strict equality contracts, and useful to compromise on features that are difficult to emulate perfectly. Finally, we validate that the proposed design patterns are used in practical wrappers

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