A heuristic-based approach to code-smell detection

Encapsulation and data hiding are central tenets of the object oriented paradigm. Deciding what data and behaviour to form into a class and where to draw the line between its public and private details can make the difference between a class that is an understandable, flexible and reusable abstraction and one which is not. This decision is a difficult one and may easily result in poor encapsulation which can then have serious implications for a number of system qualities. It is often hard to identify such encapsulation problems within large software systems until they cause a maintenance problem (which is usually too late) and attempting to perform such analysis manually can also be tedious and error prone. Two of the common encapsulation problems that can arise as a consequence of this decomposition process are data classes and god classes. Typically, these two problems occur together – data classes are lacking in functionality that has typically been sucked into an over-complicated and domineering god class. This paper describes the architecture of a tool which automatically detects data and god classes that has been developed as a plug-in for the Eclipse IDE. The technique has been evaluated in a controlled study on two large open source systems which compare the tool results to similar work by Marinescu, who employs a metrics-based approach to detecting such features. The study provides some valuable insights into the strengths and weaknesses of the two approache

Unification of Safety-Critical Java

International audienceIn response to increasing interest in the use of objectoriented technology for development of safety-critical systems, the new DO-178C guidelines will include supplements to address object-oriented technology, model-driven development, formal methods, and development tool qualification [1]. These supplements correlate well with the emerging safety-critical Java standard. As a portable object-oriented programming language enabling high levels of abstraction, safety-critical Java is an ideal candidate for automatic code generation for programming models. The use of formal methods toprove the absence of certain memory management errors at run time is a critical distinction between safety-critical Java and the Real-Time Specification for Java (RTSJ) [2]. And the specialized development tools that facilitate the use of these formal methods will, in the ideal, be qualified so that the results of their analysis can be relied upon as trustworthy safety certification evidence

The Impact Of Design Patterns In Refactoring Technique To Measure Performance Efficiency

Designing and developing software application has never been an easy task. The process is often time consuming and requires interaction between several different aspects. It will be harder in re-engineering the legacy system through refactoring technique, especially when consider to achieve software standard quality. Performance is one of the essential a quality attribute of software quality. Many studies in the literature have premise that design patterns improve the quality of object-oriented software systems but some studies suggest that the use of design patterns do not always result in appropriate designs. There are remaining question issues on negative or positive impacts of pattern refactoring in performance. In practice, refactoring in any part or structure of the system may take effect to another related part or structure. Effect of the process using refactoring technique and design patterns may improve software quality by making it more performable efficiency. Considerable research has been devoted in re-designing the system to improve software quality as maintainability and reliability. Less attention has been paid in measuring impact of performance efficiency quality factor. The main idea of this thesis is to investigate the impact, demonstrate how design patterns can be used to refactor the legacy software application in term of performance efficiency. It is therefore beneficial to investigate whether design patterns may influence performance of applications. In the thesis, an enterprise project named SIA (Sistem Informasi Akademik) is designed by applying Java EE platform. Some issues related to design patterns are addressed. The selection of design pattern is based on the application context issue. There are three kind of parameters measure, time behavior, resource utilization and capacity measures that based on standard guideline. We use tools support in experimentation as Apache JMeter and Java Mission Control. These tools provide convenient and generate appropriate result of performance measurement. The experiment results shown that the comparison between the legacy and refactored system that implemented design pattern indicates influence on application quality, especially on performance efficiency. ================================================================================================== Merancang dan mengembangkan aplikasi perangkat lunak bukan merupakan pekerjaan yang mudah karena membutuhkan waktu dan interaksi antara beberapa aspek. Proses desain pada rekayasa ulang akan lebih sulit meskipun melalui teknik refactoring, terutama untuk mencapai standar kualitas perangkat lunak. Kinerja merupakan salah satu atribut terpenting kualitas perangkat lunak. Banyak penelitian menjelaskan pola desain memperbaiki kualitas sistem perangkat lunak berorientasi objek, namun beberapa penelitian juga menunjukkan bahwa penggunaan pola desain tidak selalu menghasilkan desain yang sesuai. Masih ada pertanyaan tentang dampak negatif atau positif dari kinerja pola refactoring. Pada praktiknya, melakukan refactoring pada suatu bagian atau struktur sistem akan berpengaruh pada bagian atau struktur lain yang terkait. Penggunaan teknik refactoring dan pola desain dapat meningkatkan kualitas perangkat lunak dengan kinerja lebih efisien. Sudah banyak penelitian yang berfokus untuk merancang ulang sistem untuk meningkatkan kualitas perangkat lunak sebagai kemampuan rawatan dan keandalan. Tetapi masih kurang penelitian perhatian dalam mengukur dampak faktor kualitas efisiensi kinerja. Tujuan utama dalam tesis ini adalah untuk mengetahui dampaknya, menunjukkan bagaimana pola desain dapat digunakan untuk refactor aplikasi perangkat lunak terdahulu dalam hal efisiensi kinerja. Oleh karena itu, akan bermanfaat untuk menyelidiki apakah pola desain dapat mempengaruhi kinerja aplikasi. Dalam tesis ini, sebuah proyek perusahaan bernama SIA (Sistem Informasi Akademik) dirancang dengan menerapkan platform Java EE. Beberapa masalah yang terkait dengan pola desain diketahui. Pemilihan pola desain berdasarkan pada isu konteks aplikasi. Tiga jenis ukuran parameter dipakai untuk penilitian ini, perilaku waktu, pemanfaatan sumber daya dan ukuran kapasitas yang berdasarkan pada pedoman standar. Kami menggunakan Apache JMeter dan Java Mission Control sebagai alat bantu dalam eksperimen. Hasil percobaan menunjukkan bahwa perbandingan antara sistem terdahulu dengan penelitian ini yang menerapkan pola desain menunjukkan bahwa hasilnya berpengaruh terhadap kualitas aplikasi terutama pada efisiensi kinerja

Towards an aspect weaving BPEL engine

This position paper proposes the use of dynamic aspects and the visitor design pattern to obtain a highly configurable and extensible BPEL engine. Using these two techniques, the core of this infrastructural software can be customised to meet new requirements and add features such as debugging, execution monitoring, or changing to another Web Service selection policy. Additionally, it can easily be extended to cope with customer-specific BPEL extensions. We propose the use of dynamic aspects not only on the engine itself but also on the workflow in order to tackle the problems of Web Service hot deployment and hot fixes to long running processes. In this way, composing aWeb Service "on-the-fly" means weaving its choreography interface into the workflow

Improving Reuse of Distributed Transaction Software with Transaction-Aware Aspects

Implementing crosscutting concerns for transactions is difficult, even using Aspect-Oriented Programming Languages (AOPLs) such as AspectJ. Many of these challenges arise because the context of a transaction-related crosscutting concern consists of loosely-coupled abstractions like dynamically-generated identifiers, timestamps, and tentative value sets of distributed resources. Current AOPLs do not provide joinpoints and pointcuts for weaving advice into high-level abstractions or contexts, like transaction contexts. Other challenges stem from the essential complexity in the nature of the data, operations on the data, or the volume of data, and accidental complexity comes from the way that the problem is being solved, even using common transaction frameworks. This dissertation describes an extension to AspectJ, called TransJ, with which developers can implement transaction-related crosscutting concerns in cohesive and loosely-coupled aspects. It also presents a preliminary experiment that provides evidence of improvement in reusability without sacrificing the performance of applications requiring essential transactions. This empirical study is conducted using the extended-quality model for transactional application to define measurements on the transaction software systems. This quality model defines three goals: the first relates to code quality (in terms of its reusability); the second to software performance; and the third concerns software development efficiency. Results from this study show that TransJ can improve the reusability while maintaining performance of TransJ applications requiring transaction for all eight areas addressed by the hypotheses: better encapsulation and separation of concern; loose Coupling, higher-cohesion and less tangling; improving obliviousness; preserving the software efficiency; improving extensibility; and hasten the development process

The advantages and cost effectiveness of database improvement methods

Relational databases have proved inadequate for supporting new classes of applications, and as a consequence, a number of new approaches have been taken (Blaha 1998), (Harrington 2000). The most salient alternatives are denormalisation and conversion to an object-oriented database (Douglas 1997). Denormalisation can provide better performance but has deficiencies with respect to data modelling. Object-oriented databases can provide increased performance efficiency but without the deficiencies in data modelling (Blaha 2000). Although there have been various benchmark tests reported, none of these tests have compared normalised, object oriented and de-normalised databases. This research shows that a non-normalised database for data containing type code complexity would be normalised in the process of conversion to an objectoriented database. This helps to correct badly organised data and so gives the performance benefits of de-normalisation while improving data modelling. The costs of conversion from relational databases to object oriented databases were also examined. Costs were based on published benchmark tests, a benchmark carried out during this study and case studies. The benchmark tests were based on an engineering database benchmark. Engineering problems such as computer-aided design and manufacturing have much to gain from conversion to object-oriented databases. Costs were calculated for coding and development, and also for operation. It was found that conversion to an object-oriented database was not usually cost effective as many of the performance benefits could be achieved by the far cheaper process of de-normalisation, or by using the performance improving facilities provided by many relational database systems such as indexing or partitioning or by simply upgrading the system hardware. It is concluded therefore that while object oriented databases are a better alternative for databases built from scratch, the conversion of a legacy relational database to an object oriented database is not necessarily cost effective

Optimización del rendimiento y la eficiencia energética en sistemas masivamente paralelos

RESUMEN Los sistemas heterogéneos son cada vez más relevantes, debido a sus capacidades de rendimiento y eficiencia energética, estando presentes en todo tipo de plataformas de cómputo, desde dispositivos embebidos y servidores, hasta nodos HPC de grandes centros de datos. Su complejidad hace que sean habitualmente usados bajo el paradigma de tareas y el modelo de programación host-device. Esto penaliza fuertemente el aprovechamiento de los aceleradores y el consumo energético del sistema, además de dificultar la adaptación de las aplicaciones. La co-ejecución permite que todos los dispositivos cooperen para computar el mismo problema, consumiendo menos tiempo y energía. No obstante, los programadores deben encargarse de toda la gestión de los dispositivos, la distribución de la carga y la portabilidad del código entre sistemas, complicando notablemente su programación. Esta tesis ofrece contribuciones para mejorar el rendimiento y la eficiencia energética en estos sistemas masivamente paralelos. Se realizan propuestas que abordan objetivos generalmente contrapuestos: se mejora la usabilidad y la programabilidad, a la vez que se garantiza una mayor abstracción y extensibilidad del sistema, y al mismo tiempo se aumenta el rendimiento, la escalabilidad y la eficiencia energética. Para ello, se proponen dos motores de ejecución con enfoques completamente distintos. EngineCL, centrado en OpenCL y con una API de alto nivel, favorece la máxima compatibilidad entre todo tipo de dispositivos y proporciona un sistema modular extensible. Su versatilidad permite adaptarlo a entornos para los que no fue concebido, como aplicaciones con ejecuciones restringidas por tiempo o simuladores HPC de dinámica molecular, como el utilizado en un centro de investigación internacional. Considerando las tendencias industriales y enfatizando la aplicabilidad profesional, CoexecutorRuntime proporciona un sistema flexible centrado en C++/SYCL que dota de soporte a la co-ejecución a la tecnología oneAPI. Este runtime acerca a los programadores al dominio del problema, posibilitando la explotación de estrategias dinámicas adaptativas que mejoran la eficiencia en todo tipo de aplicaciones.ABSTRACT Heterogeneous systems are becoming increasingly relevant, due to their performance and energy efficiency capabilities, being present in all types of computing platforms, from embedded devices and servers to HPC nodes in large data centers. Their complexity implies that they are usually used under the task paradigm and the host-device programming model. This strongly penalizes accelerator utilization and system energy consumption, as well as making it difficult to adapt applications. Co-execution allows all devices to simultaneously compute the same problem, cooperating to consume less time and energy. However, programmers must handle all device management, workload distribution and code portability between systems, significantly complicating their programming. This thesis offers contributions to improve performance and energy efficiency in these massively parallel systems. The proposals address the following generally conflicting objectives: usability and programmability are improved, while ensuring enhanced system abstraction and extensibility, and at the same time performance, scalability and energy efficiency are increased. To achieve this, two runtime systems with completely different approaches are proposed. EngineCL, focused on OpenCL and with a high-level API, provides an extensible modular system and favors maximum compatibility between all types of devices. Its versatility allows it to be adapted to environments for which it was not originally designed, including applications with time-constrained executions or molecular dynamics HPC simulators, such as the one used in an international research center. Considering industrial trends and emphasizing professional applicability, CoexecutorRuntime provides a flexible C++/SYCL-based system that provides co-execution support for oneAPI technology. This runtime brings programmers closer to the problem domain, enabling the exploitation of dynamic adaptive strategies that improve efficiency in all types of applications.Funding: This PhD has been supported by the Spanish Ministry of Education (FPU16/03299 grant), the Spanish Science and Technology Commission under contracts TIN2016-76635-C2-2-R and PID2019-105660RB-C22. This work has also been partially supported by the Mont-Blanc 3: European Scalable and Power Efficient HPC Platform based on Low-Power Embedded Technology project (G.A. No. 671697) from the European Union’s Horizon 2020 Research and Innovation Programme (H2020 Programme). Some activities have also been funded by the Spanish Science and Technology Commission under contract TIN2016-81840-REDT (CAPAP-H6 network). The Integration II: Hybrid programming models of Chapter 4 has been partially performed under the Project HPC-EUROPA3 (INFRAIA-2016-1-730897), with the support of the EC Research Innovation Action under the H2020 Programme. In particular, the author gratefully acknowledges the support of the SPMT Department of the High Performance Computing Center Stuttgart (HLRS)