Evolution, survival and anomalies

Rio, A., & Abreu, F. B. E. (2023). PHP code smells in web apps: Evolution, survival and anomalies. Journal of Systems and Software, 200, 1-23. [111644]. https://doi.org/10.1016/j.jss.2023.111644Abstract Context: Code smells are symptoms of poor design, leading to future problems, such as reduced maintainability. Therefore, it becomes necessary to understand their evolution and how long they stay in code. This paper presents a longitudinal study on the evolution and survival of code smells (CS) for web apps built with PHP, the most widely used server-side programming language in web development and seldom studied. Objectives: We aimed to discover how CS evolve and what is their survival/lifespan in typical PHP web apps. Does CS survival depend on their scope or app life period? Are there sudden variations (anomalies) in the density of CS through the evolution of web apps? Method: We analyzed the evolution of 18 CS in 12 PHP web applications and compared it with changes in app and team size. We characterized the distribution of CS and used survival analysis techniques to study CS’ lifespan. We specialized the survival studies into localized (specific location) and scattered CS (spanning multiple classes/methods) categories. We further split the observations for each web app into two consecutive time frames. As for the CS evolution anomalies, we standardized their detection criteria. Results: The CS density trend along the evolution of PHP web apps is mostly stable, with variations, and correlates with the developer’s numbers. We identified the smells that survived the most. CS live an average of about 37% of the life of the applications, almost 4 years on average in our study; around 61% of CS introduced are removed. Most applications have different survival times for localized and scattered CS, and localized CS have a shorter life. The CS survival time is shorter and more CS are introduced and removed in the first half of the life of the applications. We found anomalies in the evolution of 5 apps and show how a graphical representation of sudden variations found in the evolution of CS unveils the story of a development project. Conclusion: CS stay a long time in code. The removal rate is low and did not change substantially in recent years. An effort should be made to avoid this bad behavior and change the CS density trend to decrease.publishersversionepub_ahead_of_prin

Modelo automático de qualidade para sítios web

Dissertação apresentada na Faculdade de Ciências e Tecnologia da Universidade Nova de Lisboa para a obtenção do Grau de Mestre em Engenharia InformáticaA avaliação da qualidade de presenças na web deve levar em consideração várias vertentes como o design, estrutura dos sítios e sua navegação, conteúdos, funcionalidades e desempenho. Embora se conheçam várias iniciativas de avaliação, estas são maioritariamente de cariz qualitativo, geralmente suportadas na opinião de peritos, o que torna as avaliações caras, morosas e, acima de tudo, subjectivas. O objectivo desta dissertação é o de propor uma avaliação quantitativa e automatizada da qualidade de presenças na web. Para tal será consolidado um modelo de qualidade adequado e proposto um metamodelo representativo dos conceitos do domínio do problema. Este último deve ser instanciado para casos concretos, através da recolha automática com um crawler para captura da estrutura e analisadores léxico-sintácticos para análise de conteúdos. Serão usados indicadores quantitativos que permitam uma avaliação em valor absoluto (caracterizando os pontos fortes e fracos de um sítio) e relativo (permitindo a construção automática de classificações ordenadas de sítios). Será ainda efectuada análise estatística aos indicadores provenientes do modelo de qualidade para sitíos web. Espera-se que a utilização da aproximação proposta possa ser utilizada quer pelas equipas de desenvolvimento de sítios na web, por exemplo no estabelecimento e avaliação de conformidade com padrões mínimos, quer no apoio à decisão da subcontratação desse desenvolvimento, permitindo, por exemplo, a comparação de portfolios de sub-contratantes potenciais

MAMMALS IN PORTUGAL : A data set of terrestrial, volant, and marine mammal occurrences in P ortugal

Mammals are threatened worldwide, with 26% of all species being includedin the IUCN threatened categories. This overall pattern is primarily associatedwith habitat loss or degradation, and human persecution for terrestrial mam-mals, and pollution, open net fishing, climate change, and prey depletion formarine mammals. Mammals play a key role in maintaining ecosystems func-tionality and resilience, and therefore information on their distribution is cru-cial to delineate and support conservation actions. MAMMALS INPORTUGAL is a publicly available data set compiling unpublishedgeoreferenced occurrence records of 92 terrestrial, volant, and marine mam-mals in mainland Portugal and archipelagos of the Azores and Madeira thatincludes 105,026 data entries between 1873 and 2021 (72% of the data occur-ring in 2000 and 2021). The methods used to collect the data were: live obser-vations/captures (43%), sign surveys (35%), camera trapping (16%),bioacoustics surveys (4%) and radiotracking, and inquiries that represent lessthan 1% of the records. The data set includes 13 types of records: (1) burrowsjsoil moundsjtunnel, (2) capture, (3) colony, (4) dead animaljhairjskullsjjaws, (5) genetic confirmation, (6) inquiries, (7) observation of live animal (8),observation in shelters, (9) photo trappingjvideo, (10) predators dietjpelletsjpine cones/nuts, (11) scatjtrackjditch, (12) telemetry and (13) vocalizationjecholocation. The spatial uncertainty of most records ranges between 0 and100 m (76%). Rodentia (n=31,573) has the highest number of records followedby Chiroptera (n=18,857), Carnivora (n=18,594), Lagomorpha (n=17,496),Cetartiodactyla (n=11,568) and Eulipotyphla (n=7008). The data setincludes records of species classified by the IUCN as threatened(e.g.,Oryctolagus cuniculus[n=12,159],Monachus monachus[n=1,512],andLynx pardinus[n=197]). We believe that this data set may stimulate thepublication of other European countries data sets that would certainly contrib-ute to ecology and conservation-related research, and therefore assisting onthe development of more accurate and tailored conservation managementstrategies for each species. There are no copyright restrictions; please cite thisdata paper when the data are used in publications.info:eu-repo/semantics/publishedVersio

Mammals in Portugal: a data set of terrestrial, volant, and marine mammal occurrences in Portugal

Mammals are threatened worldwide, with ~26% of all species being included in the IUCN threatened categories. This overall pattern is primarily associated with habitat loss or degradation, and human persecution for terrestrial mammals, and pollution, open net fishing, climate change, and prey depletion for marine mammals. Mammals play a key role in maintaining ecosystems functionality and resilience, and therefore information on their distribution is crucial to delineate and support conservation actions. MAMMALS IN PORTUGAL is a publicly available data set compiling unpublished georeferenced occurrence records of 92 terrestrial, volant, and marine mammals in mainland Portugal and archipelagos of the Azores and Madeira that includes 105,026 data entries between 1873 and 2021 (72% of the data occurring in 2000 and 2021). The methods used to collect the data were: live observations/captures (43%), sign surveys (35%), camera trapping (16%), bioacoustics surveys (4%) and radiotracking, and inquiries that represent less than 1% of the records. The data set includes 13 types of records: (1) burrows | soil mounds | tunnel, (2) capture, (3) colony, (4) dead animal | hair | skulls | jaws, (5) genetic confirmation, (6) inquiries, (7) observation of live animal (8), observation in shelters, (9) photo trapping | video, (10) predators diet | pellets | pine cones/nuts, (11) scat | track | ditch, (12) telemetry and (13) vocalization | echolocation. The spatial uncertainty of most records ranges between 0 and 100 m (76%). Rodentia (n =31,573) has the highest number of records followed by Chiroptera (n = 18,857), Carnivora (n = 18,594), Lagomorpha (n = 17,496), Cetartiodactyla (n = 11,568) and Eulipotyphla (n = 7008). The data set includes records of species classified by the IUCN as threatened (e.g., Oryctolagus cuniculus [n = 12,159], Monachus monachus [n = 1,512], and Lynx pardinus [n = 197]). We believe that this data set may stimulate the publication of other European countries data sets that would certainly contribute to ecology and conservation-related research, and therefore assisting on the development of more accurate and tailored conservation management strategies for each species. There are no copyright restrictions; please cite this data paper when the data are used in publications

PHP code smells in web apps: survival and anomalies

Context: Code smells are considered symptoms of poor design, leading to future problems, such as reduced maintainability. Except for anecdotal cases (e. g. code dropout), a code smell survives until it gets explicitly refactored or removed. This paper presents a longitudinal study on the survival of code smells for web apps built with PHP. Objectives: RQ: (i) code smells survival depends on their scope? (ii) practitioners attitudes towards code smells removal in web apps have changed throughout time? (iii) how long code smells survive in web applications? (iv) are there sudden variations (anomalies) in the density of code smells through the evolution of web apps? Method: We analyze the evolution of 6 code smells in 8 web applications written in PHP at the server side, across several years, using the survival analysis technique. We classify code smells according to scope in two categories: scattered and localized. Scattered code smells are expected to be more harmful since their influence is not circumscribed as in localized code smells. We split the observations for each web app into two equal and consecutive timeframes, to test the hypothesis that code smells awareness has increased throughout time. As for the anomalies, we standardize their detection criteria. Results: We present some evidence that code smells survival depends on their scope: the average survival rate decreases in some of them, while the opposite is observed for the remainder. The survival of localized code smells is around 4 years, while the scattered ones live around 5 years. Around 60% of the smells are removed, and some live through all the application life. We also show how a graphical representation of anomalies found in the evolution of code smells allows unveiling the story of a development project and make managers aware of the need for enforcing regular refactoring practices