Impacts and Detection of Design Smells

Les changements sont faits de façon continue dans le code source des logiciels pour prendre en compte les besoins des clients et corriger les fautes. Les changements continus peuvent conduire aux défauts de code et de conception. Les défauts de conception sont des mauvaises solutions à des problèmes récurrents de conception ou d’implémentation, généralement dans le développement orienté objet. Au cours des activités de compréhension et de changement et en raison du temps d’accès au marché, du manque de compréhension, et de leur expérience, les développeurs ne peuvent pas toujours suivre les normes de conception et les techniques de codage comme les patrons de conception. Par conséquent, ils introduisent des défauts de conception dans leurs systèmes. Dans la littérature, plusieurs auteurs ont fait valoir que les défauts de conception rendent les systèmes orientés objet plus difficile à comprendre, plus sujets aux fautes, et plus difficiles à changer que les systèmes sans les défauts de conception. Pourtant, seulement quelques-uns de ces auteurs ont fait une étude empirique sur l’impact des défauts de conception sur la compréhension et aucun d’entre eux n’a étudié l’impact des défauts de conception sur l’effort des développeurs pour corriger les fautes. Dans cette thèse, nous proposons trois principales contributions. La première contribution est une étude empirique pour apporter des preuves de l’impact des défauts de conception sur la compréhension et le changement. Nous concevons et effectuons deux expériences avec 59 sujets, afin d’évaluer l’impact de la composition de deux occurrences de Blob ou deux occurrences de spaghetti code sur la performance des développeurs effectuant des tâches de compréhension et de changement. Nous mesurons la performance des développeurs en utilisant: (1) l’indice de charge de travail de la NASA pour leurs efforts, (2) le temps qu’ils ont passé dans l’accomplissement de leurs tâches, et (3) les pourcentages de bonnes réponses. Les résultats des deux expériences ont montré que deux occurrences de Blob ou de spaghetti code sont un obstacle significatif pour la performance des développeurs lors de tâches de compréhension et de changement. Les résultats obtenus justifient les recherches antérieures sur la spécification et la détection des défauts de conception. Les équipes de développement de logiciels doivent mettre en garde les développeurs contre le nombre élevé d’occurrences de défauts de conception et recommander des refactorisations à chaque étape du processus de développement pour supprimer ces défauts de conception quand c’est possible. Dans la deuxième contribution, nous étudions la relation entre les défauts de conception et les fautes. Nous étudions l’impact de la présence des défauts de conception sur l’effort nécessaire pour corriger les fautes. Nous mesurons l’effort pour corriger les fautes à l’aide de trois indicateurs: (1) la durée de la période de correction, (2) le nombre de champs et méthodes touchés par la correction des fautes et (3) l’entropie des corrections de fautes dans le code-source. Nous menons une étude empirique avec 12 défauts de conception détectés dans 54 versions de quatre systèmes: ArgoUML, Eclipse, Mylyn, et Rhino. Nos résultats ont montré que la durée de la période de correction est plus longue pour les fautes impliquant des classes avec des défauts de conception. En outre, la correction des fautes dans les classes avec des défauts de conception fait changer plus de fichiers, plus les champs et des méthodes. Nous avons également observé que, après la correction d’une faute, le nombre d’occurrences de défauts de conception dans les classes impliquées dans la correction de la faute diminue. Comprendre l’impact des défauts de conception sur l’effort des développeurs pour corriger les fautes est important afin d’aider les équipes de développement pour mieux évaluer et prévoir l’impact de leurs décisions de conception et donc canaliser leurs efforts pour améliorer la qualité de leurs systèmes. Les équipes de développement doivent contrôler et supprimer les défauts de conception de leurs systèmes car ils sont susceptibles d’augmenter les efforts de changement. La troisième contribution concerne la détection des défauts de conception. Pendant les activités de maintenance, il est important de disposer d’un outil capable de détecter les défauts de conception de façon incrémentale et itérative. Ce processus de détection incrémentale et itérative pourrait réduire les coûts, les efforts et les ressources en permettant aux praticiens d’identifier et de prendre en compte les occurrences de défauts de conception comme ils les trouvent lors de la compréhension et des changements. Les chercheurs ont proposé des approches pour détecter les occurrences de défauts de conception, mais ces approches ont actuellement quatre limites: (1) elles nécessitent une connaissance approfondie des défauts de conception, (2) elles ont une précision et un rappel limités, (3) elles ne sont pas itératives et incrémentales et (4) elles ne peuvent pas être appliquées sur des sous-ensembles de systèmes. Pour surmonter ces limitations, nous introduisons SMURF, une nouvelle approche pour détecter les défauts de conception, basé sur une technique d’apprentissage automatique — machines à vecteur de support — et prenant en compte les retours des praticiens. Grâce à une étude empirique portant sur trois systèmes et quatre défauts de conception, nous avons montré que la précision et le rappel de SMURF sont supérieurs à ceux de DETEX et BDTEX lors de la détection des occurrences de défauts de conception. Nous avons également montré que SMURF peut être appliqué à la fois dans les configurations intra-système et inter-système. Enfin, nous avons montré que la précision et le rappel de SMURF sont améliorés quand on prend en compte les retours des praticiens.Changes are continuously made in the source code to take into account the needs of the customers and fix the faults. Continuous change can lead to antipatterns and code smells, collectively called “design smells” to occur in the source code. Design smells are poor solutions to recurring design or implementation problems, typically in object-oriented development. During comprehension and changes activities and due to the time-to-market, lack of understanding, and the developers’ experience, developers cannot always follow standard designing and coding techniques, i.e., design patterns. Consequently, they introduce design smells in their systems. In the literature, several authors claimed that design smells make object-oriented software systems more difficult to understand, more fault-prone, and harder to change than systems without such design smells. Yet, few of these authors empirically investigate the impact of design smells on software understandability and none of them authors studied the impact of design smells on developers’ effort. In this thesis, we propose three principal contributions. The first contribution is an empirical study to bring evidence of the impact of design smells on comprehension and change. We design and conduct two experiments with 59 subjects, to assess the impact of the composition of two Blob or two Spaghetti Code on the performance of developers performing comprehension and change tasks. We measure developers’ performance using: (1) the NASA task load index for their effort; (2) the time that they spent performing their tasks; and, (3) their percentages of correct answers. The results of the two experiments showed that two occurrences of Blob or Spaghetti Code design smells impedes significantly developers performance during comprehension and change tasks. The obtained results justify a posteriori previous researches on the specification and detection of design smells. Software development teams should warn developers against high number of occurrences of design smells and recommend refactorings at each step of the development to remove them when possible. In the second contribution, we investigate the relation between design smells and faults in classes from the point of view of developers who must fix faults. We study the impact of the presence of design smells on the effort required to fix faults, which we measure using three metrics: (1) the duration of the fixing period; (2) the number of fields and methods impacted by fault-fixes; and, (3) the entropy of the fault-fixes in the source code. We conduct an empirical study with 12 design smells detected in 54 releases of four systems: ArgoUML, Eclipse, Mylyn, and Rhino. Our results showed that the duration of the fixing period is longer for faults involving classes with design smells. Also, fixing faults in classes with design smells impacts more files, more fields, and more methods. We also observed that after a fault is fixed, the number of occurrences of design smells in the classes involved in the fault decreases. Understanding the impact of design smells on development effort is important to help development teams better assess and forecast the impact of their design decisions and therefore lead their effort to improve the quality of their software systems. Development teams should monitor and remove design smells from their software systems because they are likely to increase the change efforts. The third contribution concerns design smells detection. During maintenance and evolution tasks, it is important to have a tool able to detect design smells incrementally and iteratively. This incremental and iterative detection process could reduce costs, effort, and resources by allowing practitioners to identify and take into account occurrences of design smells as they find them during comprehension and change. Researchers have proposed approaches to detect occurrences of design smells but these approaches have currently four limitations: (1) they require extensive knowledge of design smells; (2) they have limited precision and recall; (3) they are not incremental; and (4) they cannot be applied on subsets of systems. To overcome these limitations, we introduce SMURF, a novel approach to detect design smells, based on a machine learning technique—support vector machines—and taking into account practitioners’ feedback. Through an empirical study involving three systems and four design smells, we showed that the accuracy of SMURF is greater than that of DETEX and BDTEX when detecting design smells occurrences. We also showed that SMURF can be applied in both intra-system and inter-system configurations. Finally, we reported that SMURF accuracy improves when using practitioners’ feedback

Prediction of the demand for drinking water in a context of humanitarian crisis. Rharous case (Mali).

La calidad de gestión del abastecimiento urbano de agua muy dependiente de la capacidad para predecir la demanda. De dicha predicción depende conseguir objetivos fundamentales, como la obtención de un suministro continuado con la presión y calidad de servicio adecuadas. En este sentido, durante décadas se han ido proponiendo diferentes métodos para la predicción de la demanda: desde los clásicos modelos ARIMA, hasta los actuales métodos de Aprendizaje Automático. En este trabajo se aplican método de predicción de la demanda de agua potable a un contexto de crisis humanitario generado por el conflicto, a partir de series de consumos de agua y de las variables demográficas y climáticas. Tras aplicar diversos modelos, se optó por uno que combina modelos de regresión y modelos de ARIMA. La componente estacional y la tendencia contribuyen respectivamente a un 65% y 13% de la variabilidad de la demanda. Otras variaciones periódicas (semanales y mensuales) socioculturales, suponen un 2%. El error del modelo de regresión que predice la componente estacional, la parte no explicada de la predicción realizada por los modelos ARIMA es aproximadamente el 3.5% de la demanda total. Con todos estos componentes se dispone de un modelo de predicción capaz de estimar con bastante fiabilidad, la demanda total, a partir del tamaño de la población y del clima y del día del mes.The quality of urban water supply management is highly dependent on the ability to predict demand. The achievement of fundamental objectives, such as obtaining a continuous supply with adequate pressure and quality of service, depends on this prediction. In this sense, for decades different methods have been proposed for the prediction of demand: from the classic ARIMA models to the current methods of Automatic Learning. In this work, a method of predicting the demand for drinking water is applied to a context of humanitarian crisis generated by the conflict, based on series of water consumption and demographic and climatic variables. After applying different models, one was chosen that combines regression models and ARIMA models. The seasonal component and the trend contribute respectively to 65% and 13% of the variability of demand. Other sociocultural periodic (weekly and monthly) variations account for 2%. The error of the regression model predicted by the seasonal component. The unexplained part of the prediction made by the ARIMA models is approximately 3.5% of total demand. With all these components, a prediction model is available that is capable to estimate total demand fairly reliably, based on the size of the population and the climate and the day of the month.Máster Universitario en Hidrología y Gestión de Recursos Hídrico

Insuffisance Rénale Aigue Obstétricale : Expérience De La Maternité Issaka GAZOBY De Niamey (Niger)

Introduction Acute renal failure (ARF) is a serious obstetric complication of pregnancy, a real health problem in developing countries. It is more related to the pathologies of pregnancy affecting the mother rather than the fetus. The purpose of our study was to assess sociodemographic, clinical, therapeutic and evolutionary features in obstetric acute renal failure. Materials and Methods: A cross sectional study of 6 months (August 2015- January 2016) was conducted. The study involved pregnant women over 20- week amenorrhea including the immediate postpartum admitted for acute renal failure. Results: Thirty-two patients were involved. The mean age was 25.21 ± 5.14 years. Most of them were first-time mothers (53.1%). Surrounding hospital exits account for 71.9% of the admissions. 31.25% (N = 10) of the patients did not receive any antenatal care. The main clinical signs at admission were hypertension (86.6%), oliguria (40.5%) and edema syndrome (37.5%). Eclampsia and severe pre-eclampsia represented the causes of the ARF in 68.75% cases. Considering 8 patients (25%) who were supposed to undergo dialysis therapy, only one took the treatment. The average hospital stay was 15.20 ± 7.45 days. Renal function resolved in 68.75% of patients and 15.62% developed chronic renal sequelae. At the end of the study, we recorded 5 cases of maternal deaths and 10 cases of fetal death in utero. Conclusion: Obstetric ARF remains a serious complication of pregnancy for mother and child. It should be noted that hemodialysis was not accessible to all patients who were entitled to it due to lack of financial means. Therefore, regular monitoring of pregnancies should be prioritized, and, if possible, ensure that hemodialysis sessions are funded

Impact of Drought and Land – Use Changes on Surface – Water Quality and Quantity: The Sahelian Paradox

International audienceAfrique de l'Ouest a connu des conditions de sécheresse depuis la fin des années 1960. Cette tendance a été particulièrement évident dans le Sahel, mais semble avoir atténué dans la dernière décennie dans les régions orientales et centrales de cette région. D'autre part, la pluviométrie annuelle reste très faible dans la partie ouest du Sahel [ 1 ]. Une diminution correspondante a également été observé dans le débit moyen annuel des fleuves Sénégal et Niger, qui sont le plus grand dans la région et principalement alimenté par l'eau provenant de régions tropicales humides. Toutefois, le pourcentage de diminution du débit annuel moyen était presque deux fois plus grande que la diminution des précipitations [ 2 ] pour la période 1970-2010. Des tendances similaires ont été observées sur des réseaux hydrographiques plus petits. En revanche, même si le Sahel et la plupart de l'Afrique de l'Ouest ont connu la sécheresse aussi importante au cours des 40 dernières années, les coefficients de ruissellement et des débits d'eau ont augmenté dans la plupart des régions du Sahel. Ce phénomène a été appelé «Le Sahel Paradox" après l'augmentation de la nappe phréatique au Niger depuis les années 1960, a été nommé le paradoxe de Niamey et attribués à des changements importants dans l'utilisation des terres. Le les (Afrique multidisciplinaire de la mousson d'analyse) programmes AMMA HAPEX-Sahel (hydrologique et Expérience atmosphérique pilote) et ont fourni, parmi de nombreux résultats complets, les mesures de valeur portant sur les variations spatiales et temporelles de la teneur en eau du sol sahélienne ainsi que de l'infiltration de l'eau à travers les couches profondes du sol de la zone non saturée. Le but de ce chapitre est de fournir un aperçu du comportement hydrologique en Afrique de l'Ouest basée sur le point, locale, méso et échelles régionales observations

Elective cancer surgery in COVID-19-free surgical pathways during the SARS-CoV-2 pandemic: An international, multicenter, comparative cohort study

PURPOSE As cancer surgery restarts after the first COVID-19 wave, health care providers urgently require data to determine where elective surgery is best performed. This study aimed to determine whether COVID-19–free surgical pathways were associated with lower postoperative pulmonary complication rates compared with hospitals with no defined pathway. PATIENTS AND METHODS This international, multicenter cohort study included patients who underwent elective surgery for 10 solid cancer types without preoperative suspicion of SARS-CoV-2. Participating hospitals included patients from local emergence of SARS-CoV-2 until April 19, 2020. At the time of surgery, hospitals were defined as having a COVID-19–free surgical pathway (complete segregation of the operating theater, critical care, and inpatient ward areas) or no defined pathway (incomplete or no segregation, areas shared with patients with COVID-19). The primary outcome was 30-day postoperative pulmonary complications (pneumonia, acute respiratory distress syndrome, unexpected ventilation). RESULTS Of 9,171 patients from 447 hospitals in 55 countries, 2,481 were operated on in COVID-19–free surgical pathways. Patients who underwent surgery within COVID-19–free surgical pathways were younger with fewer comorbidities than those in hospitals with no defined pathway but with similar proportions of major surgery. After adjustment, pulmonary complication rates were lower with COVID-19–free surgical pathways (2.2% v 4.9%; adjusted odds ratio [aOR], 0.62; 95% CI, 0.44 to 0.86). This was consistent in sensitivity analyses for low-risk patients (American Society of Anesthesiologists grade 1/2), propensity score–matched models, and patients with negative SARS-CoV-2 preoperative tests. The postoperative SARS-CoV-2 infection rate was also lower in COVID-19–free surgical pathways (2.1% v 3.6%; aOR, 0.53; 95% CI, 0.36 to 0.76). CONCLUSION Within available resources, dedicated COVID-19–free surgical pathways should be established to provide safe elective cancer surgery during current and before future SARS-CoV-2 outbreaks

Elective Cancer Surgery in COVID-19-Free Surgical Pathways During the SARS-CoV-2 Pandemic: An International, Multicenter, Comparative Cohort Study.

PURPOSE: As cancer surgery restarts after the first COVID-19 wave, health care providers urgently require data to determine where elective surgery is best performed. This study aimed to determine whether COVID-19-free surgical pathways were associated with lower postoperative pulmonary complication rates compared with hospitals with no defined pathway. PATIENTS AND METHODS: This international, multicenter cohort study included patients who underwent elective surgery for 10 solid cancer types without preoperative suspicion of SARS-CoV-2. Participating hospitals included patients from local emergence of SARS-CoV-2 until April 19, 2020. At the time of surgery, hospitals were defined as having a COVID-19-free surgical pathway (complete segregation of the operating theater, critical care, and inpatient ward areas) or no defined pathway (incomplete or no segregation, areas shared with patients with COVID-19). The primary outcome was 30-day postoperative pulmonary complications (pneumonia, acute respiratory distress syndrome, unexpected ventilation). RESULTS: Of 9,171 patients from 447 hospitals in 55 countries, 2,481 were operated on in COVID-19-free surgical pathways. Patients who underwent surgery within COVID-19-free surgical pathways were younger with fewer comorbidities than those in hospitals with no defined pathway but with similar proportions of major surgery. After adjustment, pulmonary complication rates were lower with COVID-19-free surgical pathways (2.2% v 4.9%; adjusted odds ratio [aOR], 0.62; 95% CI, 0.44 to 0.86). This was consistent in sensitivity analyses for low-risk patients (American Society of Anesthesiologists grade 1/2), propensity score-matched models, and patients with negative SARS-CoV-2 preoperative tests. The postoperative SARS-CoV-2 infection rate was also lower in COVID-19-free surgical pathways (2.1% v 3.6%; aOR, 0.53; 95% CI, 0.36 to 0.76). CONCLUSION: Within available resources, dedicated COVID-19-free surgical pathways should be established to provide safe elective cancer surgery during current and before future SARS-CoV-2 outbreaks

The evolving SARS-CoV-2 epidemic in Africa: Insights from rapidly expanding genomic surveillance

INTRODUCTION Investment in Africa over the past year with regard to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) sequencing has led to a massive increase in the number of sequences, which, to date, exceeds 100,000 sequences generated to track the pandemic on the continent. These sequences have profoundly affected how public health officials in Africa have navigated the COVID-19 pandemic. RATIONALE We demonstrate how the first 100,000 SARS-CoV-2 sequences from Africa have helped monitor the epidemic on the continent, how genomic surveillance expanded over the course of the pandemic, and how we adapted our sequencing methods to deal with an evolving virus. Finally, we also examine how viral lineages have spread across the continent in a phylogeographic framework to gain insights into the underlying temporal and spatial transmission dynamics for several variants of concern (VOCs). RESULTS Our results indicate that the number of countries in Africa that can sequence the virus within their own borders is growing and that this is coupled with a shorter turnaround time from the time of sampling to sequence submission. Ongoing evolution necessitated the continual updating of primer sets, and, as a result, eight primer sets were designed in tandem with viral evolution and used to ensure effective sequencing of the virus. The pandemic unfolded through multiple waves of infection that were each driven by distinct genetic lineages, with B.1-like ancestral strains associated with the first pandemic wave of infections in 2020. Successive waves on the continent were fueled by different VOCs, with Alpha and Beta cocirculating in distinct spatial patterns during the second wave and Delta and Omicron affecting the whole continent during the third and fourth waves, respectively. Phylogeographic reconstruction points toward distinct differences in viral importation and exportation patterns associated with the Alpha, Beta, Delta, and Omicron variants and subvariants, when considering both Africa versus the rest of the world and viral dissemination within the continent. Our epidemiological and phylogenetic inferences therefore underscore the heterogeneous nature of the pandemic on the continent and highlight key insights and challenges, for instance, recognizing the limitations of low testing proportions. We also highlight the early warning capacity that genomic surveillance in Africa has had for the rest of the world with the detection of new lineages and variants, the most recent being the characterization of various Omicron subvariants. CONCLUSION Sustained investment for diagnostics and genomic surveillance in Africa is needed as the virus continues to evolve. This is important not only to help combat SARS-CoV-2 on the continent but also because it can be used as a platform to help address the many emerging and reemerging infectious disease threats in Africa. In particular, capacity building for local sequencing within countries or within the continent should be prioritized because this is generally associated with shorter turnaround times, providing the most benefit to local public health authorities tasked with pandemic response and mitigation and allowing for the fastest reaction to localized outbreaks. These investments are crucial for pandemic preparedness and response and will serve the health of the continent well into the 21st century