Metrics suite for maintainability of eXtensible Markup Language web services

The eXtensible Markup Language (XML) web services are emerging as the de-facto mechanism for exchanging structured information between applications. The large popularity and acceptance of web services led the developers to adopt the best practices of web service implementation and to find the ways for managing and maintaining web services more effectively. Maintainability, one of the important factors, which affects the quality of XML web services, can be controlled by the proper software metrics that are specifically designed and developed for it. In this paper, we present a suite of metrics to evaluate the quality of the XML web service in terms of its maintainability. The present suite of metrics includes: data weight of a web service description language, distinct message ratio metric, message entropy metric and message repetition scale metric. All the proposed metrics have been evaluated theoretically and validated empirically. A comparative study with similar measures proves the worth of the metric suite

Tool Support for Cascading Style Sheets’ Complexity Metrics

Tools are the fundamental requirement for acceptability of any metrics programme in the software industry. It is observed that majority of the metrics proposed and are available in the literature lack tool support. This is one of the reasons why they are not widely accepted by the practitioners. In order to improve the acceptability of proposed metrics among software engineers that develop Web applications, there is need to automate the process. In this paper, we have developed a tool for computing metrics for Cascading Style Sheets (CSS) and named it as CSS Analyzer (CSSA). The tool is capable of measuring different metrics, which are the representation of different quality attributes: which include understandability, reliability and maintainability based on some previously proposed metrics. The tool was evaluated by comparing its result on 40 cascading style sheets with results gotten by the manual process of computing the complexities. The results show that the tool computes in far less time when compared to the manual process and is 51.25% accurate

A DISCUSSION ON ASSURING SOFTWARE QUALITY IN SMALL AND MEDIUM SOFTWARE ENTERPRISES: AN EMPIRICAL INVESTIGATION

Under the studies of general core activities including software inspection, review and testing to achieve quality objectives in small-medium size enterprises (SMEs), the paper presents a contemporary view of such companies against quality measures. The results from a local empirical investigation of quality standards in the Turkish software industry are reported.Around 150 software companies have been approached from which 17 detailed feedback inform that in order to ensure software quality, standards including internationally recognized International Standards Organization (ISO) and Capability Maturity Model Integration (CMMI) are given credit. However the substantial workload and resources required to obtain them are also reported as serious; downscaled frameworks of such large models proposed in the literature are not well known by the SMEs either. The paper also discusses "work around" that bypasses such standards to ease delivery of products while keeping certificates as labels just to acquire new jobs for the business

Qos-Based Web Service Discovery And Selection Using Machine Learning

In service computing, the same target functions can be achieved by multiple Web services from different providers. Due to the functional similarities, the client needs to consider the non-functional criteria. However, Quality of Service provided by the developer suffers from scarcity and lack of reliability. In addition, the reputation of the service providers is an important factor, especially those with little experience, to select a service. Most of the previous studies were focused on the user's feedbacks for justifying the selection. Unfortunately, not all the users provide the feedback unless they had extremely good or bad experience with the service. In this vision paper, we propose a novel architecture for the web service discovery and selection. The core component is a machine learning based methodology to predict the QoS properties using source code metrics. The credibility value and previous usage count are used to determine the reputation of the service.Comment: 8 Pages, 3 Figure

Web service QoS prediction using improved software source code metrics

Due to the popularity of Web-based applications, various developers have provided an abundance of Web services with similar functionality. Such similarity makes it challenging for users to discover, select, and recommend appropriate Web services for the service-oriented systems. Quality of Service (QoS) has become a vital criterion for service discovery, selection, and recommendation. Unfortunately, service registries cannot ensure the validity of the available quality values of the Web services provided online. Consequently, predicting the Web services' QoS values has become a vital way to find the most appropriate services. In this paper, we propose a novel methodology for predicting Web service QoS using source code metrics. The core component is aggregating software metrics using inequality distribution from micro level of individual class to the macro level of the entire Web service. We used correlation between QoS and software metrics to train the learning machine. We validate and evaluate our approach using three sets of software quality metrics. Our results show that the proposed methodology can help improve the efficiency for the prediction of QoS properties using its source code metrics

Estimating Web Service Interface Quality through Conventional Object-oriented Metrics [Latindex]

Historically, software engineers have conceived metric suites as valuable tools to estimate the quality of their software artifacts. Recently, a fresh computing paradigm called Service-Oriented Computing (SOC) has emerged at the crossing of massively distributed and heterogeneous software. This paper presents a statistical correlation analysis showing that classic software engineering metrics can be used to predict the most relevant quality attributes of WSDL documents, the essential software artifact when materializing this novel computing paradigm with Web-based technologies. For the experiments, two recent WSDL-level metrics catalogs and 154 real world WSDL documents have been employed.Fil: Ordiales Coscia, Jose Luis. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico - CONICET - Tandil. Instituto Superior de Ingenieria del Software; Argentina;Fil: Crasso, Marco Patricio. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico - CONICET - Tandil. Instituto Superior de Ingenieria del Software; Argentina;Fil: Mateos Diaz, Cristian Maximiliano. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico - CONICET - Tandil. Instituto Superior de Ingenieria del Software; Argentina;Fil: Zunino Suarez, Alejandro Octavio. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico - CONICET - Tandil. Instituto Superior de Ingenieria del Software; Argentina

COBOL systems migration to SOA: Assessing antipatterns and complexity

SOA and Web Services allow users to easily expose business functions to build larger distributed systems. However, legacy systems - mostly in COBOL - are left aside unless applying a migration approach. The main approaches are direct and indirect migration. The former implies wrapping COBOL programs with a thin layer of a Web Service oriented language/platform. The latter needs reengineering COBOL functions to a modern language/ platform. In our previous work, we presented an intermediate approach based on direct migration where developed Web Services are later refactored to improve the quality of their interfaces. Refactorings mainly capture good practices inherent to indirect migration. For this, antipatterns for WSDL documents (common bad practices) are detected to prevent issues related to WSDLs understanding and discoverability. In this paper, we assess antipatterns of Web Services’ WSDL documents generated upon the three migration approaches. In addition, generated Web Services’ interfaces are measured in complexity to attend both comprehension and interoperability. We apply a metric suite (by Baski & Misra) to measure complexity on services interfaces - i.e., WSDL documents. Migrations of two real COBOL systems upon the three approaches were assessed on antipatterns evidences and the complexity level of the generated SOA frontiers - a total of 431 WSDL documents.Fil: Mateos Diaz, Cristian Maximiliano. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tandil. Instituto Superior de Ingeniería del Software. Universidad Nacional del Centro de la Provincia de Buenos Aires. Instituto Superior de Ingeniería del Software; ArgentinaFil: Zunino Suarez, Alejandro Octavio. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tandil. Instituto Superior de Ingeniería del Software. Universidad Nacional del Centro de la Provincia de Buenos Aires. Instituto Superior de Ingeniería del Software; ArgentinaFil: Flores, Andrés Pablo. Universidad Nacional del Comahue. Facultad de Informática. Departamento Ingeniería de Sistemas; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte; ArgentinaFil: Misra, Sanjay. Atilim University; Turquía. Covenant University; Nigeri

EARLY ASSESSMENT OF SERVICE PERFORMANCE USING SIMULATION

The success of web services is changing the way in which software is designed, developed, and distributed. The increasing diffusion of software in the form services, available as commodities over the Internet, has en- abled business scenarios where processes are implemented by composing loosely-coupled services chosen at runtime. Services are in fact continuously re-designed and incrementally developed, released in heterogeneous and distributed environments, and selected and integrated at runtime within external business processes. In this dynamic context, there is the need of solutions supporting the evaluation of service performance at an early stage of the software development process, or even at design time, to support users in an a priori evaluation of the impact, a given service might have when integrated in their business process. A number of useful performance verification and validation techniques are proposed to test and simulate web services, but they assume the availability of service code or at least of reliable information (e.g., collected by testing) on service behavior. Among these approaches, simulation-based techniques are mostly used to assess the behavior of the service and predict its behavior using historical data. Despite the benefits of such solutions, few proposals have addressed the problem of how service performance can be assessed at design time and how historical data can be replaced by simulation data for performance evaluation at early stage of development cycle. In this thesis, the notion of simulation is fully integrated within early phases of the software development process in order to predict the behavior of services. We propose model-based approaches that rely on the amount of information available for the simulation of the performance of service operations. We distinguish full-knowledge, partial-knowledge and zero-knowledge scenarios. In a full-knowledge scenario, the total execution times for each operation and the internal distributions of delays are known and used for performance evaluation. In a partial-knowledge scenario, partial testing results (i.e., the lower and upper bounds to the operation execution times) are used to simulate a service performance. In the zero-knowledge scenario, no testing results are considered; only simulation results are used for performance evaluation. The main contributions of this thesis can be summarized as follows. Firstly, we proposed a model-based approach that relies on Symbolic Transition System (STS) to describe the web services as finite state automata and evaluate their performance. This model was extended for testing and simulation. The testing model annotates model transitions with performance idioms, which allow to evaluate the behavior of the service. The simulation model extends the standard STS-based model with transition probabilities and delay distributions. This model is used to generate a simulation script that allows to simulate the service behavior. Our methodology used simulation along the design and pre-deployment phases of the web service lifecycle to preliminarily assess web service performance using coarse-grained information on the total execution time of each service operation derived by testing. We used testing results and provided some practical examples to validate our methodology and the quality of the performance measurements computed by simulation considering the full-knowledge and partial-knowledge scenarios. The results obtained showed that our simulation gives accurate estimation of the execution times. Secondly, the thesis proposed an approach that permits service developers and software adopters to evaluate service performance in a zero-knowledge scenario, where testing results and service code are not yet available. Our approach is built on expert knowledge to estimate the execution time of the service operation. It evaluates the complexity of the service operation using the input and output Simple Object Access Protocol (SOAP) messages, and the Web Service Description Language (WSDL) interface of the service. Then, the operation interval of execution times is estimated based on profile tables providing the time overhead needed to parse and build SOAP messages, and the performance inferred from the testing of some reference service operations. Our simulation results showed that our zero-knowledge approach gives an accurate approximation of the interval of execution times when compared with the testing results at the end of the development. Thirdly, the thesis proposed an application of our previous approaches to the definition of a framework that allows to negotiate and monitoring the performance Service Level Agreement (SLA) of the web service based on the simulation data. The solution for SLA monitoring is based on the STS-based model for testing and the solution for SLA negotiation is based on the service model for simulation. This work provides an idea about the SLA of the service in advance and how to handle the violations of the SLA on performance after the service deployment.Le succ\ue8s des services Web est entrain de changer la fa\ue7on dont le logiciel est con\ue7u, d\ue9velopp\ue9 et distribu\ue9. La diffusion croissante des logiciels sous forme de services, disponibles en tant que produits sur Internet, a permis la d\ue9finition de sc\ue9narios d\u2019entreprise o\uf9 les processus sont mis en \u153uvre par la composition de services faiblement coupl\ue9s, choisis au moment de l\u2019ex\ue9cution. Les services sont en effet en permanence re-con\ue7us et d\ue9velopp\ue9s progressivement, publi\ue9s dans des environnements h\ue9t\ue9rog\ue8nes et distribu\ue9s, et s\ue9lectionn\ue9s et int\ue9gr\ue9s \ue0 l\u2019ex\ue9cution dans les processus externes d\u2019entreprise. Dans ce contexte dynamique, il est n\ue9cessaire d\u2019avoir des solutions permettant l'\ue9valuation de la performance du service \ue0 un stade pr\ue9coce du processus de d\ue9veloppement des logiciels, ou encore au moment de la conception, afin de permettre aux utilisateurs de faire une \ue9valuation \u201ca priori\u201d de l\u2019impact qu\u2019un service donn\ue9 peut avoir quand il est int\ue9gr\ue9 dans leur processus d\u2019entreprise. Un certain nombre de techniques de v\ue9rification et de validation des performances utiles sont propos\ue9es pour tester et simuler les services web, mais elles requi\ue8rent la disponibilit\ue9 du code source du service ou au moins d\u2019informations fiables (par exemple, recueillies par test) sur le comportement du service. Parmi ces approches, les techniques bas\ue9es sur la simulation sont principalement utilis\ue9es pour \ue9valuer le comportement du service et pr\ue9dire son comportement en utilisant des donn\ue9es obtenues par test. Malgr\ue9 les avantages de ces solutions, peu de propositions ont abord\ue9 le probl\ue8me li\ue9 \ue0 la mani\ue8re dont la performance du service peut \ueatre \u301\ue9valu\ue9e au moment de la conception et comment les donn\ue9es de test peuvent \ueatre remplac\ue9es par les donn\ue9es de simulation en vue de l\u2019\ue9valuation de la performance \ue0 un stade pr\ue9coce du cycle de d\ue9veloppement. Dans cette th\ue8se, la notion de simulation est enti\ue8rement int\ue9gr\ue9e dans les premi\ue8res phases du processus de d\ue9veloppement des logiciels afin de pr\ue9dire le comportement des services. Nous proposons des approches bas\ue9es sur l\u2019utilisation de mod\ue8les s\u2019appuyant sur la quantit\ue9 d\u2019informations disponibles pour la simulation de la performance des op\ue9rations du service web. Nous distinguons les sc\ue9narios full-knowledge, partial-knowledge et zero-knowledge. Dans un sc\ue9nario full-knowledge, les temps d\u2019ex\ue9cution total de chaque op\ue9ration et les distributions internes des d\ue9lais sont connus et utilis\ue9s pour l\u2019\ue9valuation des performances. Dans un sc\ue9nario partial-knowledge, les r\ue9sultats des tests partiels (par exemple, les bornes inf\ue9rieures et sup\ue9rieures des temps d\u2019ex\ue9cution de l\u2019op\ue9ration) sont utilis\ue9s pour simuler la performance du service web. Dans le sc\ue9nario zero-knowledge, aucun r\ue9sultat de test n\u2019est consid\ue9r\ue9, seuls les r\ue9sultats de simulation sont utilis\ue9s pour l\u2019\ue9valuation des performances. Les principales contributions de cette th\ue8se peuvent \ueatre r\ue9sum\ue9es comme suit. Premi\ue8rement, nous avons propos\ue9 une approche bas\ue9e sur l\u2019utilisation de mod\ue8le qui s\u2019appuie sur le Syst\ue8me de Transition Symbolique ( STS ) pour d\ue9crire les services web comme des automates \ue0 \u301\ue9tats finis et \ue9valuer leur performance. Ce mod\ue8le a \u301\ue9t\ue9 \ue9tendu pour les tests et la simulation. Le mod\ue8le de test ajoute aux transitions du mod\ue8le STS standard des idiomes de performance, qui permettent d\u2019\ue9valuer le comportement du service. Cependant, le mod\ue8le de simulation \ue9tend le mod\ue8le STS standard avec des probabilit\ue9s de transition et les distributions de d\ue9lais. Ce mod\ue8le est utilis\ue9 pour g\ue9n\ue9rer un script de simulation permettant de simuler le comportement du service. Notre m\ue9thodologie utilise la simulation tout au long des phases de conception et de pr\ue9-d\ue9ploiement du cycle de vie des services web pour une \ue9valuation pr\ue9liminaire de la performance des services web en utilisant les informations brutes sur le temps total d\u2019ex\ue9cution de chaque op\ue9ration du service web provenant des tests. Nous avons utilis\ue9 les r\ue9sultats des tests et fourni des exemples concrets pour valider notre m\ue9thodologie et la qualit\ue9 des mesures de performance obtenues par simulation en consid\ue9rant les sc\ue9narios full-knowledge et partial-knowledge. Les r\ue9sultats obtenus ont montr\ue9 que notre simulation donne une estimation pr\ue9cise des temps d\u2019ex\ue9cution. Deuxi\ue8mement, notre th\ue8se a propos\ue9 une approche qui permet aux d\ue9veloppeurs de services web et aux utilisateurs des logiciels d\u2019\ue9valuer la performance des services en consid\ue9rant le sc\ue9nario zero-knowledge , o\uf9 les r\ue9sultats des tests et le code source des services ne sont pas encore disponibles. Notre approche est fond\ue9e sur les connaissances des experts pour estimer le temps d\u2019ex\ue9cution de l\u2019op\ue9ration du service web. Il \ue9value la complexit\ue9 de l\u2019op\ue9ration en utilisant les messages SOAP (Simple Object Access Protocol) d\u2019entr\ue9e et de sortie et l\u2019interface de description WSDL (Web Service Description Language) du service. Ensuite, l\u2019intervalle du temps d\u2019ex\ue9cution de l\u2019op\ue9ration est estim\ue9 sur la base des tables de profils fournissant le temps n\ue9cessaire pour parser et construire les messages SOAP, et la performance d\ue9duite \ue0 partir du test de certaines op\ue9rations de web services de r\ue9f\ue9rence. Nos r\ue9sultats de simulation ont montr\ue9 que notre sc\ue9nario zero-knowledge donne une bonne approximation de l\u2019intervalle du temps d\u2019ex\ue9cution par rapport aux r\ue9sultats des tests obtenus \ue0 la fin du d\ue9veloppement. Troisi\ue8mement, cette th\ue8se propose une application de nos pr\ue9c\ue9dentes approches pour la mise en place d\u2019un framework qui permet de n\ue9gocier et de surveiller le contrat de niveau de service (SLA) sur la performance du service web en se basant sur les donn\ue9es de simulation. La solution pour le suivi du contrat de niveau de service est bas\ue9e sur le mod\ue8le STS \ue9tendu pour le test et la solution de n\ue9gociation du niveau de service est bas\ue9e sur le mod\ue8le de service \ue9tendu pour la simulation. Ce travail fournit \ue0 l\u2019avance une id\ue9e sur le contrat de performance du service et la fa\ue7on dont les violations du contrat sont trait\ue9es apr\ue8s le d\ue9ploiement du service web