175 research outputs found
Facilitating Feature-Oriented Quality Assurance in Low-Maturity Variant-rich Systems
No full textContext: Many software systems exist in several variants customized for specific stakeholder requirements, such as different market segments or hardware constraints. This customization introduces a high level of complexity that renders traditional single-system quality assurance techniques inapplicable, since they need to consider variations and constraints between a system’s features—a.k.a feature-oriented or variability-aware analysis. While several analysis techniques have been conceived in the last two decades for this purpose, they mostly target a branch of variant-rich systems called software product lines, and are less applicable to systems that still rely on cloning strategies to engineer variants—a.k.a low-maturity variant-rich systems. Among other reasons, this is because such systems exhibit: immature architectures that do not systematically account for variability, redundancy that is not exploited to reduce analysis effort, and missing essential meta-information such as feature constraints and locations of features in source code.
Objective: This research aims to facilitate quality assurance in low-maturity variant-rich systems. Through analysis of the state-of-practice, we propose techniques that can improve maturity and help developers of such systems mitigate some challenges posed by redundancy.
Method: First, we conducted a survey and interviews with practitioners to identify industrial needs and practices for analyzing variant-rich systems, followed by a case study of some open source systems to understand where developers record information necessary for feature-oriented analysis. Then, we designed and systematically evaluated a technique and a tool that can improve the maturity of variant rich systems by supporting feature recording, and two techniques that can reduce analysis effort.
Results: Our results stem from two main contributions: our analysis of the state-of-practice and techniques we propose for improving maturity to facilitate feature-oriented analysis in low-maturity variant-rich systems. For the former, we present results of a survey and interviews targeting 27 practitioners from 18 companies in 8 countries to understand industrial practices and needs for analyzing variant-rich systems. Then, we present our empirical understanding of features and their characteristics (facets) based on a case study of two industrial open-source systems. For the latter, we present design decisions and an evaluation of a tool and technique that help developers proactively and continuously record features. Then, we present empirical data on the potential of two techniques for reducing QA effort: one for predicting software defects at the level of features (evaluated on 13 open-source systems), and another for propagating test cases across forked projects, i.e., projects with similar but cloned features (evaluated on over 426,000 test cases from 2,153 projects).
Conclusion: This thesis identifies the lack of adoption of feature-oriented quality assurance techniques in industry, and addresses the problem through tools and techniques for feature recording and quality assurance effort reduction
Vegetation structure characteristics and relationships of Kalahari woodlands and savannas
No full textThe Kalahari Transect is one of several International Geosphere–Biosphere Programme (IGBP) transects designed to address global change questions at the regional scale, in particular by exploiting natural parameter gradients (Koch et al., 1995). In March 2000, we collected near-synoptic vegetation structural data at five sites spanning the Kalahari's large precipitation gradient (about 300–1000 mm yr?1) from southern Botswana (?24°S) to Zambia (?15°S). All sites were within the expansive Kalahari sandsheet. Common parameters, including plant area index (PAI), leaf area index (LAI) and canopy cover (CC), were measured or derived using several indirect instruments and at multiple spatial scales. Results show that CC and PAI increase with increasing mean annual precipitation. Canopy clumping, defined by the deviation of the gap size distribution from that of randomly distributed foliage, was fairly constant along the gradient. We provide empirical relationships relating these parameters to each other and to precipitation. These results, combined with those in companion Kalahari Transect studies, provide a unique and coherent test bed for ecological modeling. The data may be used to parameterize process models, as well as test internally predicted parameters and their variability in response to well-characterized climatological differences.<br/
Verification of migrated product lines
No full textMaintaining several code bases (e.g., clones) of software variants in an application domain remains a widespread development practice, though costly and error-prone. Despite the many benefits that come with using the product-line approach, many companies are hesitant to migrate to an integrated platform for their product variants because such a migration is considered challenging and risky. Often this perception is because the migration is seen as a drastic change that is not easy to verify and assure developers that the migrated products still operate as before. In this research we propose to develop a language structure (or abstract representation) of artifacts in a software asset base that would facilitate an incremental migration of several code bases to an integrated platform. We further seek to propose and evaluate techniques for verifying the migrated product line with respect to its original code bases
Understanding Variability-Aware Analysis in Low-Maturity Variant-Rich Systems
No full textContext: Software systems often exist in many variants to support varying stakeholder requirements, such as specific market segments or hardware constraints. Systems with many variants (a.k.a. variant-rich systems) are highly complex due to the variability introduced to support customization. As such, assuring the quality of these systems is also challenging since traditional single-system analysis techniques do not scale when applied. To tackle this complexity, several variability-aware analysis techniques have been conceived in the last two decades to assure the quality of a branch of variant-rich systems called software product lines. Unfortunately, these techniques find little application in practice since many organizations do use product-line engineering techniques, but instead rely on low-maturity \clo~strategies to manage their software variants. For instance, to perform an analysis that checks that all possible variants that can be configured by customers (or vendors) in a car personalization system conform to specified performance requirements, an organization needs to explicitly model system variability. However, in low-maturity variant-rich systems, this and similar kinds of analyses are challenging to perform due to (i) immature architectures that do not systematically account for variability, (ii) redundancy that is not exploited to reduce analysis effort, and (iii) missing essential meta-information, such as relationships between features and their implementation in source code.Objective: The overarching goal of the PhD is to facilitate quality assurance in low-maturity variant-rich systems. Consequently, in the first part of the PhD (comprising this thesis) we focus on gaining a better understanding of quality assurance needs in such systems and of their properties.Method: Our objectives are met by means of (i) knowledge-seeking research through case studies of open-source systems as well as surveys and interviews with practitioners; and (ii) solution-seeking research through the implementation and systematic evaluation of a recommender system that supports recording the information necessary for quality assurance in low-maturity variant-rich systems. With the former, we investigate, among other things, industrial needs and practices for analyzing variant-rich systems; and with the latter, we seek to understand how to obtain information necessary to leverage variability-aware analyses.Results: Four main results emerge from this thesis: first, we present the state-of-practice in assuring the quality of variant-rich systems, second, we present our empirical understanding of features and their characteristics, including information sources for locating them; third, we present our understanding of how best developers\u27 proactive feature location activities can be supported during development; and lastly, we present our understanding of how features are used in the code of non-modular variant-rich systems, taking the case of feature scattering in the Linux kernel.Future work: In the second part of the PhD, we will focus on processes for adapting variability-aware analyses to low-maturity variant-rich systems.Keywords:\ua0Variant-rich Systems, Quality Assurance, Low Maturity Software Systems, Recommender Syste
Understanding Variability-Aware Analysis in Low-Maturity Variant-Rich Systems
No full textContext: Software systems often exist in many variants to support varying stakeholder requirements, such as specific market segments or hardware constraints. Systems with many variants (a.k.a., variant-rich systems) are highly complex due to the variability introduced to support customization. As such, assuring quality of these systems is also challenging since traditional single-system analysis techniques do not scale when applied. To tackle this complexity, several variability-aware analysis techniques have been conceived in the last two decades to assure the quality of a branch of variant-rich systems called software product lines. Unfortunately, many organizations do not use product-line engineering techniques, but instead rely on low-maturity clone-and-own strategies to manage their software variants. Hence, they cannot apply the proposed analysis techniques. For instance, to perform an analysis that checks that all possible variants that can be configured by customers (or vendors) in a car personalization system conform to specified performance requirements, an organization needs to explicitly model system variability. However, in low-maturity variant-rich systems, this and similar kinds of analyses are challenging to perform due to (i) immature architectures that do not systematically account for variability, (ii) redundancy that is not exploited to reduce analysis effort, and (iii) missing essential meta-information, such as relationships between features and their implementation in source code. Objective: The overarching goal of the PhD is to facilitate quality assurance in low-maturity variant-rich systems. Consequently, in the first part of the PhD (comprising this thesis) we focus on gaining a better understanding of quality assurance needs in such systems and of their properties. Method: Our objectives are met by means of (i) knowledge-seeking research through case studies of open-source systems as well as surveys and interviews with practitioners; and (ii) solution-seeking research through the implementation and systematic evaluation of a recommender system that supports recording the information necessary for quality assurance in low-maturity variant-rich systems. With the former, we investigate, among other things, industrial needs and practices for analyzing variant-rich systems; and with the latter, we seek to understand how to obtain information necessary to leverage variability-aware analyses. Results and Conclusions: Four main results emerge from this thesis: first, we present the state-of-practice in assuring the quality of variant-rich systems, second, we present our empirical understanding of features and their characteristics, including information sources for locating them; third, we present our understanding of how best developers' proactive feature location activities can be supported during development; and lastly, we present our understanding of how features are used in the code of non-modular variant-rich systems, taking the case of feature scattering in the Linux kernel. Future work: In the second part of the PhD, we will focus on processes for adapting variability-aware analyses to low-maturity variant-rich systems
Early spatial and temporal validation of MODIS LAI product in the Southern Africa Kalahari
No full textWe evaluate the operational MODIS Leaf Area Index (LAI) product using field-sampled data collected at five sites in southern Africa in March 2000. One site (Mongu, Zambia) was sampled monthly throughout the year. All sites were along the International Geosphere Biosphere Programme's (IGBP) Kalahari Transect, which features progressively lower annual precipitation, and hence, lower vegetation productivity, from north to south. The soils are consistently sandy. At each site, we sampled the vegetation overstory along three 750-m transects using the Tracing Radiation and Architecture in Canopies (TRAC) instrument. The resulting plant area index values were adjusted with ancillary stem area data to estimate LAI. Despite some instrument characterization and production issues in the first year of MODIS operations, our results suggest the first-year MODIS LAI algorithm correctly accommodates structural and phenological variability in semiarid woodlands and savannas, and is accurate to within the uncertainty of the validation approach used here. Limitations of this study and its conclusions are also discussed.<br/
Facilitating Feature-Oriented Quality Assurance in Low-Maturity Variant-rich Systems
No full textContext: Many software systems exist in several variants customized for specific stakeholder requirements, such as different market segments or hardware constraints. This customization introduces a high level of complexity that renders traditional single-system quality assurance techniques inapplicable, since they need to consider variations and constraints between a system’s features—a.k.a feature-oriented or variability-aware analysis. While several analysis techniques have been conceived in the last two decades for this purpose, they mostly target a branch of variant-rich systems called software product lines, and are less applicable to systems that still rely on cloning strategies to engineer variants—a.k.a low-maturity variant-rich systems. Among other reasons, this is because such systems exhibit: immature architectures that do not systematically account for variability, redundancy that is not exploited to reduce analysis effort, and missing essential meta-information such as feature constraints and locations of features in source code. Objective: This research aims to facilitate quality assurance in low-maturity variant-rich systems. Through analysis of the state-of-practice, we propose techniques that can improve maturity and help developers of such systems mitigate some challenges posed by redundancy. Method: First, we conducted a survey and interviews with practitioners to identify industrial needs and practices for analyzing variant-rich systems, followed by a case study of some open source systems to understand where developers record information necessary for feature-oriented analysis. Then, we designed and systematically evaluated a technique and a tool that can improve the maturity of variant rich systems by supporting feature recording, and two techniques that can reduce analysis effort. Results: Our results stem from two main contributions: our analysis of the state-of-practice and techniques we propose for improving maturity to facilitate feature-oriented analysis in low-maturity variant-rich systems. For the former, we present results of a survey and interviews targeting 27 practitioners from 18 companies in 8 countries to understand industrial practices and needs for analyzing variant-rich systems. Then, we present our empirical understanding of features and their characteristics (facets) based on a case study of two industrial open-source systems. For the latter, we present design decisions and an evaluation of a tool and technique that help developers proactively and continuously record features. Then, we present empirical data on the potential of two techniques for reducing QA effort: one for predicting software defects at the level of features (evaluated on 13 open-source systems), and another for propagating test cases across forked projects, i.e., projects with similar but cloned features (evaluated on over 426,000 test cases from 2,153 projects). Conclusion: This thesis identifies the lack of adoption of feature-oriented quality assurance techniques in industry, and addresses the problem through tools and techniques for feature recording and quality assurance effort reduction
Understanding Variability-Aware Analysis in Low-Maturity Variant-Rich Systems [Elektronisk resurs]
No full textContext : Software systems often exist in many variants to support varying stakeholder requirements, such as specific market segments or hardware constraints. Systems with many variants (a.k.a. variant-rich systems) are highly complex due to the variability introduced to support customization. As such, assuring the quality of these systems is also challenging since traditional single-system analysis techniques do not scale when applied. To tackle this complexity, several variability-aware analysis techniques have been conceived in the last two decades to assure the quality of a branch of variant-rich systems called software product lines. Unfortunately, these techniques find little application in practice since many organizations do use product-line engineering techniques, but instead rely on low-maturity \clo~strategies to manage their software variants. For instance, to perform an analysis that checks that all possible variants that can be configured by customers (or vendors) in a car personalization system conform to specified performance requirements, an organization needs to explicitly model system variability. However, in low-maturity variant-rich systems, this and similar kinds of analyses are challenging to perform due to (i) immature architectures that do not systematically account for variability, (ii) redundancy that is not exploited to reduce analysis effort, and (iii) missing essential meta-information, such as relationships between features and their implementation in source code. Objective : The overarching goal of the PhD is to facilitate quality assurance in low-maturity variant-rich systems. Consequently, in the first part of the PhD (comprising this thesis) we focus on gaining a better understanding of quality assurance needs in such systems and of their properties. Method : Our objectives are met by means of (i) knowledge-seeking research through case studies of open-source systems as well as surveys and interviews with practitioners; and (ii) solution-seeking research through the implementation and systematic evaluation of a recommender system that supports recording the information necessary for quality assurance in low-maturity variant-rich systems. With the former, we investigate, among other things, industrial needs and practices for analyzing variant-rich systems; and with the latter, we seek to understand how to obtain information necessary to leverage variability-aware analyses. Results : Four main results emerge from this thesis: first, we present the state-of-practice in assuring the quality of variant-rich systems, second, we present our empirical understanding of features and their characteristics, including information sources for locating them; third, we present our understanding of how best developers' proactive feature location activities can be supported during development; and lastly, we present our understanding of how features are used in the code of non-modular variant-rich systems, taking the case of feature scattering in the Linux kernel. Future work : In the second part of the PhD, we will focus on processes for adapting variability-aware analyses to low-maturity variant-rich systems. Keywords : Variant-rich Systems, Quality Assurance, Low Maturity Software Systems, Recommender Syste
Evaluation of Olyset insecticide-treated nets distributed seven years previously in Tanzania.
No full textBACKGROUND: Insecticide-treated nets represent currently a key malaria control strategy, but low insecticide re-treatment rates remain problematic. Olyset nets are currently one of two long-lasting insecticidal nets recommended by WHO. An assessment was carried out of the effect of Olyset nets after seven years of use in rural Tanzania. METHODS: A survey of Olyset nets was conducted in two Tanzanian villages to examine their insecticide dosage, bioassay efficacy and desirability compared with ordinary polyester nets. RESULTS: Of 103 randomly selected nets distributed in 1994 to 1995, 100 could be traced. Most nets were in a condition likely to offer protection against mosquito biting. Villagers appreciated mainly the durability of Olyset trade mark nets and insecticide persistence. People disliked the small size of these nets and the light blue colour and preferred a smaller mesh size, features that can easily be modified. At equal price, 51% said they would prefer to buy an Olyset net and 49% opted for an ordinary polyester net. The average permethrin content was 33%-41% of the initial insecticide dose of 20,000 mg/Kg. Bioassay results indicated high knock-down rates at 60 minutes, but the mosquito mortality after 24 hours was rather low (mean: 34%). No significant correlation was found between bioassay results and insecticide concentration in and on the net. CONCLUSIONS: Olyset nets are popular, durable and with a much longer insecticide persistence than ordinary polyester nets. Hence, Olyset nets are one of the best choices for ITN programmes in rural malaria-endemic areas
Specification, design, and verification of an accountability-aware surveillance protocol
No full textCopyright 2017 ACM. Though controversial, surveillance activities are more and more performed for security reasons. However, such activities are extremely privacy-intrusive. This is seen as a necessary side-effect to ensure the success of such operations. In this paper, we propose an accountability-aware protocol designed for surveillance purposes. It relies on a strong incentive for a surveillance organisation to register its activity to a data protection authority. We first elicit a list of accountability requirements, we provide an architecture showing the interaction of the different involved parties, and we propose an accountability-aware protocol which is formally specified in the applied pi calculus. We use the ProVerif tool to automatically verify that the protocol respects confidentiality, integrity and authentication properties
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