Cohesion-Driven Decomposition of Service Interfaces Without Access to Source Code

Software cohesion concerns the degree to which the elements of a module belong together. Cohesive software is easier to understand, test and maintain. Improving cohesion is the target of several refactoring methods that have been proposed until now. These methods are tailored to operate by taking the source code into consideration. In the context of service-oriented development, cohesion refers to the degree to which the operations of a service interface belong together. In this context, we propose an approach for the cohesion-driven decomposition of service interfaces. The very philosophy of services dictates that all that is exported by a service is the service specification. Hence, our approach for the cohesion-driven decomposition of service interfaces is not based on how the services are implemented. Instead, it relies only on information provided in the specification of the service interfaces. We validate the approach in 22 real-world services provided by Amazon and Yahoo. We show the effectiveness of the proposed approach, concerning the cohesion improvement and the size of the produced decompositions. Moreover, we show that the proposed approach is useful, by conducting a user study, where developers assessed the quality of the produced decompositions

Cohesion-Driven Decomposition of Service Interfaces without Access to Source Code

International audience—Software cohesion concerns the degree to which the elements of a module belong together. Cohesive software is easier to understand, test and maintain. In the context of service-oriented development, cohesion refers to the degree to which the operations of a service interface belong together. In the state of the art, software cohesion is improved based on refactoring methods that rely on information, extracted from the software implementation. This is a main limitation towards using these methods in the case of Web services: Web services do not expose their implementation; instead all that they export is the Web service interface specification. To deal with this problem, we propose an approach that enables the cohesion-driven decomposition of service interfaces, without information on how the services are implemented. Our approach progressive decomposes a given service interface into more cohesive interfaces; the backbone of the approach is a suite of cohesion metrics that rely on information, extracted solely from the specification of the service interface. We validate the approach in 22 real-world services, provided by Amazon and Yahoo. We assess the effectiveness of the proposed approach, concerning the cohesion improvement, and the number of interfaces that result from the decomposition of the examined interfaces. Moreover, we show the usefulness of the approach in a user study, where developers assessed the quality of the produced interfaces

Exploring Maintainability Assurance Research for Service- and Microservice-Based Systems: Directions and Differences

To ensure sustainable software maintenance and evolution, a diverse set of activities and concepts like metrics, change impact analysis, or antipattern detection can be used. Special maintainability assurance techniques have been proposed for service- and microservice-based systems, but it is difficult to get a comprehensive overview of this publication landscape. We therefore conducted a systematic literature review (SLR) to collect and categorize maintainability assurance approaches for service-oriented architecture (SOA) and microservices. Our search strategy led to the selection of 223 primary studies from 2007 to 2018 which we categorized with a threefold taxonomy: a) architectural (SOA, microservices, both), b) methodical (method or contribution of the study), and c) thematic (maintainability assurance subfield). We discuss the distribution among these categories and present different research directions as well as exemplary studies per thematic category. The primary finding of our SLR is that, while very few approaches have been suggested for microservices so far (24 of 223, ?11%), we identified several thematic categories where existing SOA techniques could be adapted for the maintainability assurance of microservices

Crosscutting, what is and what is not? A Formal definition based on a Crosscutting Pattern

Crosscutting is usually described in terms of scattering and tangling. However, the distinction between these concepts is vague, which could lead to ambiguous statements. Sometimes, precise definitions are required, e.g. for the formal identification of crosscutting concerns. We propose a conceptual framework for formalizing these concepts based on a crosscutting pattern that shows the mapping between elements at two levels, e.g. concerns and representations of concerns. The definitions of the concepts are formalized in terms of linear algebra, and visualized with matrices and matrix operations. In this way, crosscutting can be clearly distinguished from scattering and tangling. Using linear algebra, we demonstrate that our definition generalizes other definitions of crosscutting as described by Masuhara & Kiczales [21] and Tonella and Ceccato [28]. The framework can be applied across several refinement levels assuring traceability of crosscutting concerns. Usability of the framework is illustrated by means of applying it to several areas such as change impact analysis, identification of crosscutting at early phases of software development and in the area of model driven software development

Identification of microservices from monolithic applications through topic modelling

Dissertação de mestrado em Informatics EngineeringMicroservices emerged as one of the most popular architectural patterns in the recent years given the increased need to scale, grow and flexibilize software projects accompanied by the growth in cloud computing and DevOps. Many software applications are being submitted to a process of migration from its monolithic architecture to a more modular, scalable and flexible architecture of microservices. This process is slow and, depending on the project’s complexity, it may take months or even years to complete. This dissertation proposes a new approach on microservices identification by resorting to topic modelling in order to identify services according to domain terms. This approach in combination with clustering techniques produces a set of services based on the original software. The proposed methodology is implemented as an open-source tool for exploration of monolithic architectures and identification of microservices. An extensive quantitative analysis using the state of the art metrics on independence of functionality and modularity of services was conducted on 200 open-source projects collected from GitHub. Cohesion at message and domain level metrics showed medians of roughly 0.6. Interfaces per service exhibited a median of 1.5 with a compact interquartile range. Structural and conceptual modularity revealed medians of 0.2 and 0.4 respectively. Further analysis to understand if the methodology works better for smaller/larger projects revealed an overall stability and similar performance across metrics. Our first results are positive demonstrating beneficial identification of services due to overall metrics’ results.Os microserviços emergiram como um dos padrões arquiteturais mais populares na atualidade dado o aumento da necessidade em escalar, crescer e flexibilizar projetos de software, acompanhados da crescente da computação na cloud e DevOps. Muitas aplicações estão a ser submetidas a processos de migração de uma arquitetura monolítica para uma arquitetura mais modular, escalável e flexivel de microserviços. Este processo de migração é lento, e dependendo da complexidade do projeto, poderá levar vários meses ou mesmo anos a completar. Esta dissertação propõe uma nova abordagem na identificação de microserviços recorrendo a modelação de tópicos de forma a identificar serviços de acordo com termos de domínio de um projeto de software. Esta abordagem em combinação com técnicas de clustering produz um conjunto de serviços baseado no projeto de software original. A metodologia proposta é implementada como uma ferramenta open-source para exploração de arquiteturas monolíticas e identificação de microserviços. Uma análise quantitativa extensa recorrendo a métricas de independência de funcionalidade e modularidade de serviços foi conduzida em 200 aplicações open-source recolhidas do GitHub. Métricas de coesão ao nível da mensagem e domínio revelaram medianas em torno de 0.6. Interfaces por serviço demonstraram uma mediana de 1.5 com um intervalo interquartil compacto. Métricas de modularidade estrutural e conceptual revelaram medianas de 0.2 e 0.4 respetivamente. Uma análise mais aprofundada para tentar perceber se a metodologia funciona melhor para projetos de diferentes dimensões/características revelaram uma estabilidade geral do funcionamento do método. Os primeiros resultados são positivos demonstrando identificações de serviços benéficos tendo em conta que os valores das métricas são de uma forma global positivos e promissores

Feature-based generation of pervasive systems architectures utilizing software product line concepts

As the need for pervasive systems tends to increase and to dominate the computing discipline, software engineering approaches must evolve at a similar pace to facilitate the construction of such systems in an efficient manner. In this thesis, we provide a vision of a framework that will help in the construction of software product lines for pervasive systems by devising an approach to automatically generate architectures for this domain. Using this framework, designers of pervasive systems will be able to select a set of desired system features, and the framework will automatically generate architectures that support the presence of these features. Our approach will not compromise the quality of the architecture especially as we have verified that by comparing the generated architectures to those manually designed by human architects. As an initial step, and in order to determine the most commonly required features that comprise the widely most known pervasive systems, we surveyed more than fifty existing architectures for pervasive systems in various domains. We captured the most essential features along with the commonalities and variabilities between them. The features were categorized according to the domain and the environment that they target. Those categories are: General pervasive systems, domain-specific, privacy, bridging, fault-tolerance and context-awareness. We coupled the identified features with well-designed components, and connected the components based on the initial features selected by a system designer to generate an architecture. We evaluated our generated architectures against architectures designed by human architects. When metrics such as coupling, cohesion, complexity, reusability, adaptability, modularity, modifiability, packing density, and average interaction density were used to test our framework, our generated architectures were found comparable, if not better than the human generated architectures

Dimensionality Reduction of Quality Objectives for Web Services Design Modularization

With the increasing use of service-oriented Architecture (SOA) in new software development, there is a growing and urgent need to improve current practice in service-oriented design. To improve the design of Web services, the search for Web services interface modularization solutions deals, in general, with a large set of conflicting quality metrics. Deciding about which and how the quality metrics are used to evaluate generated solutions are always left to the designer. Some of these objectives could be correlated or conflicting. In this paper, we propose a dimensionality reduction approach based on Non-dominated Sorting Genetic Algorithm (NSGA-II) to address the Web services re-modularization problem. Our approach aims at finding the best-reduced set of objectives (e.g. quality metrics) that can generate near optimal Web services modularization solutions to fix quality issues in Web services interface. The algorithm starts with a large number of interface design quality metrics as objectives (e.g. coupling, cohesion, number of ports, number of port types, and number of antipatterns) that are reduced based on the nonlinear correlation information entropy (NCIE).The statistical analysis of our results, based on a set of 22 real world Web services provided by Amazon and Yahoo, confirms that our dimensionality reduction Web services interface modularization approach reduced significantly the number of objectives on several case studies to a minimum of 2 objectives and performed significantly better than the state-of-the-art modularization techniques in terms of generating well-designed Web services interface for users.Master of ScienceSoftware Engineering, College of Engineering & Computer ScienceUniversity of Michigan-Dearbornhttps://deepblue.lib.umich.edu/bitstream/2027.42/145687/1/Thesis Report_Hussein Skaf.pdfDescription of Thesis Report_Hussein Skaf.pdf : Thesi