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Software organisations aim to develop and maintain high-quality software systems. Due to large amounts of behaviour data available, software organisations can conduct data-driven software maintenance. Indeed, software quality assurance and improvement programs have attracted many researchers' attention. Bayesian Networks (BNs) are proposed as a log analysis technique to discover poor performance indicators in a system and to explore usage patterns that usually require temporal analysis. For this, an action research study is designed and conducted to improve the software quality and the user experience of a web application using BNs as a technique to analyse software logs. To this aim, three models with BNs are created. As a result, multiple enhancement points have been identified within the application ranging from performance issues and errors to recurring user usage patterns. These enhancement points enable the creation of cards in the Scrum process of the web application, contributing to its data-driven software maintenance. Finally, the authors consider that BNs within quality-aware and data-driven software maintenance have great potential as a software log analysis technique and encourage the community to deepen its possible applications. For this, the applied methodology and a replication package are shared. Junta de Andalucía, Grant/Award Number: P20‐00091; AEI, Grant/Award Number: PID2019‐106758GB‐32/AEI/10.13039/501100011033; Spanish project, Grant/Award Number: PDC2021‐121195‐I00; Spanish Program, Grant/Award Number: BEAGAL18/00064

Due to recent industry needs, synergies between data science and software engineering are starting to be present in data science and engineering academic programs. Two synergies are: applying data science to manage the quality of the software (software analytics) and applying software engineering best practices in data science projects to ensure quality attributes such as maintainability and reproducibility. The lack of these synergies on academic programs have been argued to be an educational problem. Hence, it becomes necessary to explore how to teach software analytics and software engineering best practices in data science programs. In this context, we provide hands-on for conducting laboratories applying project-based learning in order to teach software analytics and software engineering best practices to data science students. We aim at improving the software engineering skills of data science students in order to produce software of higher quality by software analytics. We focus in two skills: following a process and software engineering best practices. We apply project-based learning as main teaching methodology to reach the intended outcomes. This teaching experience shows the introduction of project-based learning in a laboratory, where students applied data science and best software engineering practices to analyze and detect improvements in software quality. We carried out a case study in two academic semesters with 63 data science bachelor students. The students found the synergies of the project positive for their learning. In the project, they highlighted both utility of using a CRISP-DM data mining process and best software engineering practices like a software project structure convention applied to a data science project. This paper was partly funded by a teaching innovation project of ICE@UPC-BarcelonaTech (entitled ‘‘Audiovisual and digital material for data engineering, a teaching innovation project with open science’’), and the ‘‘Beatriz Galindo’’ Spanish Program BEA-GAL18/00064.

Context: Agile software development has become commonplace in software development companies due to the numerous benefits it provides. However, conducting Agile projects is demanding in Small and Medium Enterprises (SMEs), because projects start and end quickly, but still have to fulfil customers' quality requirements. Objective: This paper aims at reporting a practical experience on the use of metrics related to the software development process as a means supporting SMEs in the development of software following an Agile methodology. Method: We followed Action-Research principles in a Polish small-size software development company. We developed and executed a study protocol suited to the needs of the company, using a pilot case. Results: A catalogue of Agile development process metrics practically validated in the context of a small-size software development company, adopted by the company in their Agile projects. Conclusions: Practitioners may adopt these metrics in their Agile projects, especially if working in an SME, and customise them to their own needs and tools. Academics may use the findings as a baseline for new research work, including new empirical studies. The authors would like to thank all the members of the QRapids H2020 project consortium.

Static code analysis tools are designed to aid software developers to build better quality software in less time, by detecting defects early in the software development life cycle. Even the most experienced developer regularly introduces coding defects. Identifying, mitigating and resolving defects is an essential part of the software development process, but frequently defects can go undetected. One defect can lead to a minor malfunction or cause serious security and safety issues. This is magnified in the development of the complex parallel software required to exploit modern heterogeneous multicore hardware. Thus, there is an urgent need for new static code analysis tools to help in building better concurrent and parallel software. The paper reports preliminary results about the use of Appentra’s Parallelware technology to address this problem from the following three perspectives: finding concurrency issues in the code, discovering new opportunities for parallelization in the code, and generating parallel-equivalent codes that enable tasks to run faster. The paper also presents experimental results using well-known scientific codes and POWER systems. This work has been partly funded from the Spanish Ministry of Science and Technology (TIN2015-65316-P), the Departament d’Innovació, Universitats i Empresa de la Generalitat de Catalunya (MPEXPAR: Models de Programació i Entorns d’Execució Parallels, 2014-SGR-1051), and the European Union’s Horizon 2020 research and innovation program throughgrant agreements MAESTRO (801101) and EPEEC (801051).

Background: Quality requirements (QRs) describe desired system qualities, playing an important role in the success of software projects. In the context of agile software development (ASD), where the main objective is the fast delivery of functionalities, QRs are often ill-defined and not well addressed during the development process. Software analytics tools help to control quality though the measurement of quality-related software aspects to support decision-makers in the process of QR management. Aim: The goal of this research is to explore the benefits of integrating a concrete software analytics tool, Q-Rapids Tool, to assess software quality and support QR management processes. Method: In the context of a technology transfer project, the Softeam company has integrated Q-Rapids Tool in their development process. We conducted a series of workshops involving Softeam members working in the Modelio product development. Results: We present the Quality Feedback Loop (QFL) process to be integrated in software development processes to control the complete QR life-cycle, from elicitation to validation. As a result of the implementation of QFL in Softeam, Modelio's team members highlight the benefits of integrating a data analytics tool with their project planning tool and the fact that project managers can control the whole process making the final decisions. Conclusions: Practitioners can benefit from the integration of software analytics tools as part of their software development toolchain to control software quality. The implementation of QFL promotes quality in the organization and the integration of software analytics and project planning tools also improves the communication between teams., Comment: 9 pages, Accepted for publication in IEEE/ACM 43nd International Conference on Software Engineering: Software Engineering in Society (ICSE-SEIS), IEEE, 2021

[Context and motivation] Requirements reuse has been proposed asa key asset for requirements engineers to efficiently elicit, validate and document softwarer equirements and, as a consequence, obtain requirements specifications of better quality through more effective engineering processes.[Question/problem] Regardless the impact requirements reuse could have in software projects’ suc-cess and efficiency, the requirements engineering community has published veryfew studies reporting the way in which this activity is conducted in industry. [Principal ideas/results] In this paper, we present the results of an interview-based study involving 24 IT professionals on whether they reuse requirementsor not and how. Some kind of requirements reuse is carried out by the majorityof respondents, being organizational and project-related factors the main drivers.Quality requirements are the type most reused. The most common strategy isfind-copy-paste-adapt. Respondents agreed that requirements reuse is beneficial,especially for project-related reasons. The most stated challenge to overcome inrequirements reuse is related to the domain of the project and the development of acompletely new system. [Contribution] With this study, we contribute to the stateof the practice in the reuse of requirements by showing how real organizationscarry out this process and the factors that influence it. This work has been partially funded by the Horizon 2020 project OpenReq, which is supported by the European Union under the Grant Nr. 732463.

Los requisitos de calidad (también llamados requisitos no-funcionales) son aquellos que permiten asegurar la calidad del software. Incluyen aspectos muy diversos, como disponibilidad, seguridad, rendimiento, escalabilidad, portabilidad y usabilidad, entre otros. Los continuos avances tecnológicos, como el software en la nube o el Internet de las Cosas, presentan nuevos retos en el desarrollo del software para poder garantizar un nivel de calidad satisfactorio de dichos aspectos. Asimismo, las metodologías de desarrollo ágil, cuyo uso viene en aumento, tales como SCRUM, XP, Kanban, no dan el soporte necesario para la gestión de dichos requisitos de calidad. Con el fin de facilitar a los ingenieros del software la toma de decisiones sobre el nivel de calidad necesario en un proyecto, es imprescindible conocer de antemano: 1) qué criterios se van a tener en cuenta para verificar, priorizar, planificar y/o negociar los requisitos de calidad. Asimismo, es necesario: 2) precisar cómo se van a evaluar dichos criterios, y 3) identificar qué factores del contexto del proyecto pueden afectar dicha evaluación. Para intentar dar respuesta a estas 3 cuestiones o preguntas de investigación, los autores de este capítulo han diseñado y están llevando a cabo un estudio sistemático de la literatura. Este trabajo presenta para su discusión la descripción de la metodología seguida en ese estudio, así como algunos de los resultados preliminares obtenidos durante su ejecución.

Background: Practitioners would like to take action based on software metrics, as long as they find them reliable. Existing literature explores how metrics can be made reliable, but remains unclear if there are other conditions necessary for a metric to be actionable. Context & Method: In the context of a European H2020 Project, we conducted a multiple case study to study metrics’ use in four companies, and identified instances where these metrics influenced actions. We used an online questionnaire to enquire about the project participants’ views on actionable metrics. Next ,we invited one participant from each company to elaborate on the identified metrics’ use for taking actions and the questionnaire responses (N=17). Result:We learned that a metric that is practical, contextual, and exhibits high data quality characteristics is actionable. Even a non-actionable metric can be useful, but an actionable metric mostly requires interpretation. However, the more these metrics are simple and reflect the software development context accurately, the less interpretation required to infer actionable information from the metric. Company size and project characteristics can also influence the type of metric that can be actionable. Conclusion: This exploration of industry’s views on actionable metrics help characterize actionable metrics in practical terms. This awareness of what characteristics constitute an actionablemetric can facilitate theirdefinition and developmentright from the start of a software metrics program This work is a result of the Q-Rapids Project, funded by the European Union’s Horizon 2020 research and innovation program, under grant agreement No. 732253.

Background: Despite the growth in the use of software analytics platforms in industry, little empirical evidence is available about the challenges that practitioners face and the value that these platforms provide. Aim: The goal of this research is to explore the benefits of using a software analytics platform for practitioners managing quality. Method: In a technology transfer project, a software analytics platform was incrementally developed between academic and industrial partners to address their software quality problems. This paper focuses on exploring the value provided by this software analytics platform in two pilot projects. Results: Practitioners emphasized major benefits including the improvement of product quality and process performance and an increased awareness of product readiness. They especially perceived the semi-automated functionality of generating quality requirements by the software analytics platform as the benefit with the highest impact and most novel value for them. Conclusions: Practitioners can benefit from modern software analytics platforms, especially if they have time to adopt such a platform carefully and integrate it into their quality assurance activities., Comment: This is an Author's Accepted Manuscript of a paper consisting of a post-peer-review, pre-copyedit version of a paper accepted at the 13th ACM/IEEE International Symposium on Empirical Software Engineering and Measurement (ESEM), 2019. The final authenticated version is available online: https://ieeexplore.ieee.org/document/8870162

In the last decade, modern data analytics technologies have enabled the creation of software analytics tools offering real-time visualization of various aspects related to software development and usage. These tools seem to be particularly attractive for companies doing agile software development. However, the information provided by the available tools is neither aggregated nor connected to higher quality goals. At the same time, assessing and improving the software quality has also been the key targets for the software engineering community, yielding several proposals for standards and software quality models. Integrating such quality models into software analytics tools could close the gap by providing the connection to higher quality goals. This paper aims at understanding whether the integration of quality models into software analytics tools provides understandable, reliable, useful, and relevant information at the right level of detail about the quality of a process or product and whether practitioners intend to use it. Over the course of more than a year, four companies involved in this case study deployed such a tool to assess and improve software quality in several projects. We used standardized measurement instruments to elicit the perception of 22 practitioners regarding their use of the tool. We complemented the findings with debriefing sessions held at the companies. In addition, we discussed challenges and lessons learned with four practitioners leading the use of the tool. The quantitative and qualitative analyses provided positive results, i.e., the practitioners’ perception with regard to the tool’s understandability, reliability, usefulness, and relevance was positive. Individual statements support the statistical findings, and constructive feedback can be used for future improvements. We conclude that the potential for future adoption of quality models within software analytics tools definitely exists and encourage other practitioners to use the presented seven challenges and seven lessons learned and adopt them in their companies.

This work reports the objectives, current state, and outcomes of the Q-Rapids H2020 project. Q-Rapids (Quality-Aware Rapid Software Development) proposes a data-driven approach to the production of software following very short development cycles. The focus of Q-Rapids is on quality aspects, represented through quality requirements. The Q-Rapids platform, which is the tangible software asset emerging from the project, mines software repositories and usage logs to identify candidate quality requirements that may ameliorate the values of strategic indicators like product quality, time to market or team productivity. Four companies are providing use cases to evaluate the platform and associated processes.

Software quality poses continuously new challenges in software development, including aspects related to both software development and system usage, which significantly impact the success of software systems. The Q-Rapids H2020 project defines an evidence-based, data-driven quality-aware rapid software development methodology. Quality requirements (QRs) are incrementally elicited, refined and improved based on data gathered from software repositories, project management tools, system usage and quality of service. This data is analysed and aggregated into quality-related key strategic indicators (e.g., development effort required to include a given QR in the next development cycle) which are presented to decision makers using a highly informative dashboard. The Q-Rapids platform is being evaluated in-premises by the four companies participating in the consortium, reporting useful lessons learned and directions for new development.

Background: Accessing relevant data on the product, process, and usage perspectives of software as well as integrating and analyzing such data is crucial for getting reliable and timely actionable insights aimed at continuously managing software quality in Rapid Software Development (RSD). In this context, several software analytics tools have been developed in recent years. However, there is a lack of explainable software analytics that software practitioners trust. Aims: We aimed at creating a quality model (called Q-Rapids quality model) for actionable analytics in RSD, implementing it, and evaluating its understandability and relevance. Method: We performed workshops at four companies in order to determine relevant metrics as well as product and process factors. We also elicited how these metrics and factors are used and interpreted by practitioners when making decisions in RSD. We specified the Q-Rapids quality model by comparing and integrating the results of the four workshops. Then we implemented the Q-Rapids tool to support the usage of the Q-Rapids quality model as well as the gathering, integration, and analysis of the required data. Afterwards we installed the Q-Rapids tool in the four companies and performed semi-structured interviews with eight product owners to evaluate the understandability and relevance of the Q-Rapids quality model. Results: The participants of the evaluation perceived the metrics as well as the product and process factors of the Q-Rapids quality model as understandable. Also, they considered the Q-Rapids quality model relevant for identifying product and process deficiencies (e.g., blocking code situations). Conclusions: By means of heterogeneous data sources, the Q-Rapids quality model enables detecting problems that take more time to find manually and adds transparency among the perspectives of system, process, and usage., This is an Author's Accepted Manuscript of a paper to be published by IEEE in the 44th Euromicro Conference on Software Engineering and Advanced Applications (SEAA) 2018. The final authenticated version will be available online

Analyses of the interactions among quality requirements (QRs) have often found that optimizing on one QR will cause serious problems with other QRs. As just one relevant example, one large project had an Integrated Product Team optimize the system for Security. In doing so, it reduced its vulnerability profile by having a single-agent key distribution system and a single copy of the data base – only to have the Reliability engineers point on that these were system-critical single points of failure. The project’s Security-optimized architecture also created conflicts with the system’s Performance, Usability, and Modifiability. Of course, optimizing the system for Security had synergies with Reliability in having high levels of Confidentiality, Integrity, and Availability. This panel aims at fostering discussion on these relationships among QRs and how the use of data repositories may help discovering them.

We examine the determinization of monitors for HML with recursion. We demonstrate that every monitor is equivalent to a deterministic one, which is at most doubly exponential in size with respect to the original monitor. When monitors are described as CCS-like processes, this doubly exponential bound is optimal. When (deterministic) monitors are described as finite automata (as their LTS), then they can be exponentially more succinct than their CCS process form., non peer-reviewed

We advance a general technique for enriching logical systems with soft constraints, making them suitable for specifying complex software systems where parts are put together not just based on how they meet certain functional requirements but also on how they optimise certain constraints. This added expressive power is required, for example, for capturing quality attributes that need to be optimised or, more generally, for formalising what are usually called service-level agreements. More specifically, we show how institutions endowed with a graded semantic consequence can accommodate soft-constraint satisfaction problems. We illustrate our approach by showing how, in the context of service discovery, one can quantify the compatibility of two specifications and thus formalise the selection of the most promising provider of a required resource.

Enterprise Service Buses (ESBs) are highly-dynamic component platforms that are hard to test for correctness because their connected components may not necessarily be present prior to deployment. Runtime Verification (RV) is a potential solution towards ascertaining correctness of an ESB, by checking the ESB’s execution at runtime, and detecting any deviations from the expected behaviour. A crucial aspect impinging upon the feasibility of this verification approach is the runtime overheads introduced, which may have adverse effects on the execution of the ESB system being monitored. In turn, one factor that bears a major effect on such overheads is the instrumentation mechanism adopted by the RV setup. In this paper we identify three likely (but substantially different) ESB instrumentation mechanisms, detail their implementation over a widely-used ESB platform, assess them qualitatively, and empirically evaluate the runtime overheads introduced by these mechanisms., peer-reviewed

In this Master's thesis, the concept of information systems trustworthiness will be covered, in terms of describing existing methodologies for collecting and documenting security requirements as well as describing how existing methodologies support the delivery of trustworthy systems. Moreover, this essay will employ a case study, in order to enforce the essay's outcomes on how to achieve trustworthy software. Trustworthiness is a characteristic that can be applied to any system that satisfies the desired level of trust by not failing. The systems that should possess such a property are mainly systems that manage sensitive records, critical infrastructure, etc. The capturing of a system's requirements is the process of discovering and identifying the system's stakeholders and their needs. A system's requirements are the features and qualities that a system should possess, and are extracted from the system's stakeholders (i.e. owners, users). Therefore, the identification of security requirements is of crucial importance for the achievement of the desired security goals, namely trustworthiness. With respect to security requirements, in order for a system to ensure that its security specifications are satisfied, security concerns must be taken into consideration in every phase of the software engineering lifecycle; namely, from requirements engineering to design, implementation, testing, and deployment. In order to increase users' trust in the systems they use, software defects must be reduced through. Following a systematic development methodology, during the software development process, the risk of not achieving the acceptable result, is reduced, if not eliminated, since software development methodologies impose a disciplined process upon software development.

Text in English; Abstract: English and Turkish Includes bibliographical references (leaves 115-127) xix, 128 leaves There are lots of different software metrics discovered and used for defect prediction in the literature. Instead of dealing with so many metrics, it would be practical and easy if we could determine the set of metrics that are most important and focus on them more to predict defectiveness. We use Bayesian modelling to determine the influential relationships among software metrics and defect proneness. In addition to the metrics used in Promise data repository, We define two more metrics, i.e. NOD for the number of developers and LOCQ for the source code quality. We wxtract these metrics by inspecting the source code repositories of the selected Promise data repository data sets. At the end of our modeling, We learn both the marginal defect proneness probability of the whole software system and the set of most effective metrics. Our experiments on nine open source Promise data repository data sets show that respense for class (RFC), lines of code (LOC), and lack of coding quality (LOCQ) are the most efective metrics whereas coupling between objets (CBO), weighted method per class (WMC), and lack of cohesion of methods (LCOM) are less efective metris on defect proneness. Furthermore, number of children (NOC) and depth of inheritance tree (DIT) have very limited effect and are unstustworthy. On tthe other hand, based on the experiments on Poi, Tomcat, and Xalan data sets, We observe that there is a positive correlation between the number of developers (NOD) and the level of defectiveness.However, futher investigation involving a greater number of projects, is need to confirm our findings. Furthermore, we propose a novel technique for defect prediction that uses plagiarism detection tools. Although the defect prediction problem haz been researched for a long time, the results achieved are not so bright. We use kernel programming to model the relationship between source code similarity and defectiveness. Each value in the kernel matrix shows how much parallelism exit between the corresponding files ib the kernel matrix shows how much parallelism exist between the corresponding files in the software system chosen. Our experiments on 10 real world datasets indicate that support vector machines (SVM) with a precalculated kernel matrix performs better than the SVM with the usual linear and RBF kernels and generates comparable results with the famous defect prediction methods like linear logistic regression and J48 in terms of the area under the curve (AUC).Furthermore, we observed that when the amount of similarity among the files of a software system is high, then the AUC found by the SVM with precomputed kernel can be used to predict the number of defects in the files or classes of a software system, because we observe a relationship between source code similarity and the number of defects. Based on the results of our analysis, the developers can focus on more defective modules rather than on less or non defective ones during testing activities. The experiments on 10 Promise datasets indicate that while predicting the number of defects, SVM with a precomputed kernel performs as good as the SVM with the usual linear and RBF kernels, in terms of the root mean square error (RMSE). The method proposed is also comparable with other regression methods like linear regression and IBK. The results of these experiments suggest that source code similarity is a good means of predicting both defectiveness and the number of defects in software modules. Literatürde kullanılan çok çeşitli yazılım ölçütleri mevcuttur. Çok sat-yıda ölçütle hata tahmini yapmak yerine, en önemli ölçüt kümesini belirleyip bu kümedeki ölçütleri hata tahmininde kullanmak daha pratik ve kolay olacaktır. Bu tezde yazılım ölçütleri ile hataya yarkınlık arasındaki etkileşimi ortaya çıkarmak için Bayesian modelleme yöntemi kullanılmıştır. Promise veri deposundaki yazılım ölçütlerine ek olarak, yazılım geliştiricisi sayısı (NOD) ve kaynak kodu kalitesi (LOCQ) adlı 2 yeni ölçüt tanımlanmıştır. Bu ölçütleri çıkarmak için Promise veri depesundaki veri kümelerinin açık kaynak kodları kullanılmıştır. Yapılan modelleme sonucunda, hem sınanan sistemin hatalı olm aihtimali, hem de en etkili ölçüt künesi bulunmaktadır. 9 Promise veri kümesi üzerindeki deneyler, RFC, LOC ve LOCQ ölçütlerinin en etkili ölçütler olduğunu, CBO, WMC ve LCOM ölçütlerinin ise daha az etkili olduğunu ortaya koymuştur. Ayrıca, NOC ve DIT ölçütlerinin sınırlı bir etkiye sahip olduğu ve güvenilir olmadığı gözlemlenmiştir. Öte yandan, Poi, Tomcat Xalan veri kümeleri üzerinde yapılan deneyler sonucunda, yazılım geliştici sayısı (NOD) ile hata seviyesi arasında doğru orantı olduğu sonucuna varılmıştır. Bununla birlikte, tespitlerimizi doğrulamak için daha fazla veri kümesi üzerinde deney yapmaya ihtiyaç vardır. Ayrıca bu tezde, hata tahmini için intihal tespit araçlarını kullanan yeni bir yöntem önerilmiştir. Hata tahmini için intihal tespit araçlarını kullanan yeni bir yöntem önerilmiştir. Hata tahmin problemi ve uzun zamandan beri araştırılmaktadır, fakat ortaya çıkan sonuçlar çok parlak değildir. Farklı bir bakış açısı getirmek üzere, kaynak kod benzerliği ve hataya yatkınlık arasındaki ilişkiyi modelleyen çekirdek metodu yöntemi kullanılmıştır. Bu yöntemde, üretilen çekirdek matrisindeki her bir değer, matrisin satır ve sütunda bulubab kaynak kodu dosyaları arasındaki parelelliği göstermektedir. 10 veri kümesi üzerindeki deneyler, önceden hesaplanmış çekirdek matrisi kullanan SVM yönteminin, doğrusal veya RBF çekirdek kullanan SVM yöntemlerine göre daha başarılı olduğunu ayrıca mevcut hata tahmin yöntemleri doğrusal lojistik regresyon ve J48 ile benzer sonuçlar ürettiğini göstermiştir. Ayrıca, bir yazılım sistemi içerisinde bulubab dosyalar arasındaki kod benzerliğinin daha fazla olduğunu durumlarda, ROC eğrisi altındaki alan (AUC) ölçütünün de daha yüksek olduğu görülmüştür. Ayrıca, önceden hesaplanmış çekirdek matris kullanan SVM yönteminin, hata sayısı ile kaynak kodu benzerliği arasında gözlemlenen ilişkiden ötürü, bir yazılım sistemindeki hata sayısının tahmin edilmesinde de kullanılabileceği gösterilmiştir. Yapılan analiz sonucunda, yazılım geliştiriciler hatasız veya daha az hatalı modüllere odaklanmak yerine, daha fazla hata içeren modüllere odaklanabilirler. 10 Promise veri kümesi üzerinde yapılan deneyler, hata sayısını tahmin ederken, önceden hesaplanan çekirdek matris kullanan SVM yönetiminin ortalama karesel hata (RMSE) açısından doğrusal ve RBF çekirdek kullanan SVM yöntemi kadar başarılı olduğunu göstermiştir. Uygulana yöntem, doğrusal regreyon ve IBK gibi diğer regresyon yöntemleri ile benzer sonuçlar üreetmiştir. Yapılan deneylerin sonuçları, kaynak kodu benzerliğinin hataya yatkınlık ve hata sayısının tahmin etmede iyi bir araç olduğunu ortaya koymuştur. Software Metrics Static Code Metrics McCabe Metrics Line of Code Metrics Halstead Metrics Object Oriented Metrics Developer Metrics Process Metrics Defect Prediction Defect Prediction Data Performance Measure An Overview of the Defect Prediction Studies Defect Prediction Using Statistical Methods Defect Prediction Using Machine Learning Methods Previous Work on Defect Prediction Critics About Studies Benchmarking Studies Bayesian Networks Background on Bayesian Networks K2 Algorithm Previous Work on Bayesian Networks Kernel Machines Background on Kernel Machines Support Vector Machines Support Vector Machines for Regression Kernel Functions String Kernels Previous Work on Kernel Machines Plagiarism Tools Similarity Detection Kernel Methods for Defect Prediction Proposed Method Bayesian networks Bayesian network of Metrics and Defect Proneness Ordering Metrics for Bayesian Network Construction Kernel Methods to Predict Defectiveness Selecting Plagiarism Tools and Tuning Their Input Parameters Data Set Selection Kernel Matrix Generation Kernel Methods to Predict the Number of Defects Experiments and Results Experiment I: Determine Influential Relationships Among Metrics and Defectiveness Using Bayesian Networks Experiment Design Experiment II: Determine The Role Of Coding Quality And Number Of Developers On Defectiveness Using Bayesian Networks Conclusion Instability Test Effectiveness of Metric Pairs Feature Selection Tests Effectiveness of the Number of Developers (NOD) Experiment III: Defect Proneness Prediction Using Kernel Methods Experiment IV: Prediction of the Number of Defects with Kernel Methods Threats to Validity Summary of Results Bayesian Networks Kernel Methods to Predict Defectiveness Kernel Methods to Predict the Number of Defects Contributions Bayesian Networks Kernel Methods to Predict Defectiveness Kernel Methods to Predict the Number of Defects Future Work

Contract conformance is hard to determine statically, prior to the deployment of large pieces of software. A scalable alternative is to monitor for contract violations post-deployment: once a violation is detected, the trace characterising the offending execution is analysed to pinpoint the source of the offence. A major drawback with this technique is that, often, contract violations take time to surface, resulting in long traces that are hard to analyse. This paper proposes a methodology together with an accompanying tool for simplifying traces and assisting contract-violation debugging., Comment: In Proceedings FLACOS 2012, arXiv:1209.1699

In critical systems, it is frequently essential to know whether the system satisfies a number of real-time constraints, usually specified in a real-time logic such as timed regular expressions. However, after having verified a system correct, changes in its environment may slow it down or speed it up, possibly invalidating the properties. Colombo et al. (1) have presented a theory of slowdown and speedup invariance to determine which specifications are safe with respect to system retiming, and applied the approach to duration calculus. In this paper we build upon their approach, applying it to timed regular expressions. We hence identify a fragment of the logic which is invariant under the speedup or slowdown of a system, enabling more resilient verification of properties written in the logic., peer-reviewed

Technology scaling leads to burn-in phase out and increasing post-silicon test complexity, which increases in-the-field error rate due to both latent defects and actual errors. As a consequence, there is an increasing need for continuous on-line testing techniques to cope with hard errors in the field. Similarly, those techniques are needed for detecting soft errors in logic, whose error rate is expected to raise in future technologies. Cache memories, which occupy most of the area of the chip, are typically protected with parity or ECC, but most of the wires as well as some combinational blocks remain unprotected against both soft and hard errors. This paper presents a set of techniques to detect and confine hard and soft errors in cache memories in combination with parity/ECC at very low cost. By means of hard signatures in data rows and error tracking, faults can be detected, classified properly and confined for hardware reconfiguration.

Object invariants define the consistency of objects. They have subtle semantics, mainly because of call-backs, multi-object invariants, and subclassing. Several verification techniques for object invariants have been proposed. It is difficult to compare these techniques, and to ascertain their soundness, because of their differences in restrictions on programs and invariants, in the use of advanced type systems (e.g., ownership types), in the meaning of invariants, and in proof obligations. We develop a unified framework for such techniques. We distil seven parameters that characterise a verification technique, and identify sufficient conditions on these parameters which guarantee soundness. We instantiate our framework with three verification techniques from the literature, and use it to assess soundness and compare expressiveness., peer-reviewed

We develop a behavioural theory of distributed programs in the presence of failures such as nodes crashing and links breaking. The framework we use is that of Dπ, a language in which located processes, or agents, may migrate between dynamically created locations. In our extended framework, these processes run on a distributed network, in which individual nodes may crash in fail-stop fashion or the links between these nodes may become permanently broken. The original language, Dπ, is also extended by a ping construct for detecting and reacting to these failures. We define a bisimulation equivalence between these systems, based on labelled actions which record, in addition to the effect actions have on the processes, the effect on the actual state of the underlying network and the view of this state known to observers. We prove that the equivalence is fully abstract, in the sense that two systems will be differentiated if and only if, in some sense, there is a computational context, consisting of a surrounding network and an observer, which can see the difference., peer-reviewed

Complex modern software is often built using existing application frameworks and middleware frameworks. These frameworks provide useful common services, while simultaneously imposing architectural rules and constraints. Existing software architecture evaluation methods do not explicitly consider the implications of these frameworks for software architecture. This research extends scenario-based architecture evaluation methods by incorporating framework-related information into different evaluation activities. I propose four techniques which target four different activities within a scenario-based architecture evaluation method. 1) Scenario development: A new technique was designed aiming to extract general scenarios and tactics from framework-related architectural patterns. The technique is intended to complement the current scenario development process. The feasibility of the technique was validated through a case study. Significant improvements of scenario quality were observed in a controlled experiment conducted by another colleague. 2) Architecture representation: A new metrics-driven technique was created to reconstruct software architecture in a just-in-time fashion. This technique was validated in a case study. This approach has significantly improved the efficiency of architecture representation in a complex environment. 3) Attribute specific analysis (performance only): A model-driven approach to performance measurement was applied by decoupling framework-specific information from performance testing requirements. This technique was validated on two platforms (J2EE and Web Services) through a number of case studies. This technique leads to the benchmark producing more representative measures of the eventual application. It reduces the complexity behind the load testing suite and framework-specific performance data collecting utilities. 4) Trade-off and sensitivity analysis: A new technique was designed seeking to improve the Analytical Hierarchical Process (AHP) for trade-off and sensitivity analysis during a framework selection process. This approach was validated in a case study using data from a commercial project. The approach can identify 1) trade-offs implied by an architecture alternative, along with the magnitude of these trade-offs. 2) the most critical decisions in the overall decision process 3) the sensitivity of the final decision and its capability for handling quality attribute priority changes.