To encourage developers' volunteer contributions, modern programming question and answer (Q&A) sites like Stack Overflow (SO) employ gamified incentive mechanisms such as reputation and badges. Understanding developers' motivations in the presence of gamification and the relationship between their motivations and behavioral outcomes is crucial for community building and designing good incentive mechanisms. Grounded on self-determination theory, we conducted a survey with 938 developers who participate in SO to understand their participation motivations and incentive perceptions. By connecting the survey responses with the SO data, we quantitatively analyzed how the developers' motivations and satisfaction of needs relate to their effort and contribution quality. Our main findings are as follows: (1) despite the presence of gamified incentive mechanisms, developers are mainly motivated by intrinsic motivation to participate in SO; (2) developers who have strong motivations to gain gamification rewards are associated with higher intrinsic and integrated motivations, while developers with more development experiences are less motivated by the gamified incentives; (3) both extrinsic motivations (in terms of career prospects) and intrinsic motivations (regarding self-improvement and helping others) can motivate developers to make high-quantity and high-quality contributions; and (4) high-level satisfaction of needs for competency and autonomy has a positive effect on developers making high-quantity and high-quality contributions and addressing difficult problems. Based on these findings, we discuss implications for developer motivation and gamification in the crowdsourcing context and for the mechanism design of gamified crowdsourced platforms.

Modern programming question & answer (Q&A) sites such as Stack Overflow (SO) employ gamified mechanisms to stimulate volunteers' contributions. To maximize the chances of winning gamification rewards such as reputation and badges, a portion of users race to post answers as quickly as possible (i.e., fast answers or FAs), which makes SO the fastest Q&A site; however, this behavior may affect the contribution quality as well. In this paper, we report on a large-scale, mixed-methods empirical study of the gamification-influenced FA phenomenon in SO. We first quantitatively investigate the popularity of the phenomenon and user behaviors regarding FAs. Then, we study the quality of FAs by using regression modeling and qualitatively analyzing 300 instances of FAs. Our main findings reveal that more than 70% and 90% of FAs are not edited by the answerers and other users, respectively, and that later incoming answers have lower chances of being voted on and accepted. Notably, we find that the answer length, code snippets length, and readability of FAs are significantly lower than those of non-fast answers. Although FAs have higher crowd assessment scores, they have no relationship with acceptance from the perspective of asker assessment, and a considerable portion of FAs solve the problem by interacting with the asker in the comments. These results help us better understand the effects of reward-based gamification on crowdsourced software engineering communitites and provide implications for designers of gamified systems.

Abstract For popular open‐source software projects, there are always a large number of worldwide developers who have been glued to making code contributions, while most of these developers play the role of casual contributors because of their very limited code commits. The frequent turnover of such a group of developers and the wide variations in their coding experiences challenge the project management on code and quality. This paper aims to investigate the status quo of internal quality assurance for external contributions in social coding sites. We first conducted a case study of 21 popular GitHub projects to estimate the code quality of the casual contributors. The quantitative results show that the casual contributors introduced greater quantity and severity of code quality issues than the main contributors; the developers who contribute to different projects as main and casual contributors did not perform significantly differently in terms of their code quality. On the basis of these findings, we further conducted a survey of 81 developers on GitHub to understand their practices on internal quality assurance. The qualitative results expose some limitations of present internal quality control for external contributions in GitHub. Finally, we discuss an alternative quality management paradigm: Continuous Inspection for industrial practices.

For popular Open Source Software (OSS) projects there are always a large number of worldwide developers who have been glued to making code contributions, while most of these developers play the role of casual contributors due to their very limited code commits (for fixing defects and enhancing features, casually). The frequent turnover of such group of casual developers and the wide variations among their coding experiences challenge the project management on code and quality.This paper describes a case study which aims to estimate the quality of code made by casual contributors in 21 popular GitHub projects. The results of this case study show that: (1) casual contributors introduced greater quantity and severity of Code Quality Issues (CQIs) than main contributors; (2) developers who contribute in different projects as main and casual contributors didn't perform statistically differently in terms of code quality; (3) casual contributors who have few project stars introduced more CQIs than those who have many. Furthermore, the paper lists the CQI categories which are most frequently introduced by casual contributors in the investigated projects. These findings provide valuable insights into code quality in the OSS context, and can guide OSS developers in improving the quality of the code contributions.

Two practicable approaches were proposed for Web service retrieval, bipartite-graph matching and KbSM. But their models and similarity metrics of WSDL analysis may ignore some term or semantic feature, and involve formal method problem of representation or difficulty of parameter verification. SLVM and its improved model depend on statistical term measures to implement XML document representation. As a result, they ignore the lexical semantics and the distilled mutual information, leading to text analysis errors. This work proposed a service retrieval method, hybrid SLVM of WSDL, to address the problem of feature extraction. Using WordNet, this method constructed a lexical semantic spectrum to characterize the lexical semantics, and built a special term spectrum based on TF-IDF. Then, feature matrix for WSDL representation was built in the hybrid SLVM. Applying to NWKNN algorithm, on OWLS-TC version 2 dataset, the experimental results show that the feature matrix of our method performs F1 measure and query precisions better than bipartite-graph matching and KbSM.

In current cloud systems, firewall penetration of distributed resource is a practical problem. Because this problem refers the existing TCP and UDP penetration schemes, we analyze all kinds of possible transmission environments in practical applications, and then present a technique to penetrate firewalls by UDP coordinating with TCP. Finally, we submit the implement frame of this method, a network switch --XIPSwitch, which is independent of various distributed cloud paradigms. The design can further solve the firewall penetration problem of the remote terminals of distributed cloud platform in the wide area network.

It is considered that software architecture usually degrades as the system evolves. This phenomenon is termed as architectural degeneration. This paper describes a defect perspective for measuring architectural degeneration. Several metrics are defined for the measurement performed on two versions of a commercial compiler system. The main results are: (1) the architecture degenerates as the system evolves across the two versions, e.g., the quantity of code files changed to fix a source line of code in the following version increased by 90%; and (2) a few, correlated, components ("hotspots") in the architecture contribute more to the degeneration than other components. This implies that measuring architectural degeneration from the defect perspective can offer a potential to improve system quality and reduce maintenance costs.

Literature indicates that 20% of a program's code is responsible for 80% of the faults, and 50-90% of the field failures are rediscoveries of previous faults. Despite this, identification of faulty code can consume 30-40% time of error correction. Previous fault-discovery techniques focusing on field failures either require many pass-fail traces, discover only crashing failures, or identify faulty "files" (which are of large granularity) as origin of the source code. In our earlier work (the F007 approach), we identify faulty "functions" (which are of small granularity) in a field trace by using earlier resolved traces of the same release, which limits it to the known faulty functions. This paper overcomes this limitation by proposing a new "strategy" to identify new and old faulty functions using F007. This strategy uses failed traces of mutants (artificial faults) and failed traces of prior releases to identify faulty functions in the traces of succeeding release. Our results on two UNIX utilities (i.e., Flex and Gzip) show that faulty functions in the traces of the majority (60-85%) of failures of a new software release can be identified by reviewing only 20% of the code. If compared against prior techniques then this is a notable improvement in terms of contextual knowledge required and accuracy in the discovery of finer-grain fault origin.

Certain software defects require corrective changes repeatedly in a few components of the system. One type of such defects spans multiple components of the system, and we call such defects pervasive multiple-component defects (PMCDs). In this paper, we describe an empirical study of six releases of a large legacy software system (of approx. size 20 million physical lines of code) to analyze PMCDs with respect to: (1) the complexity of fixing such defects and (2) the persistence of defect-prone components across phases and releases. The overall hypothesis in this study is that PMCDs inflict a greater negative impact than do other defects on defect-correction efficacy. Our findings show that the average number of changes required for fixing PMCDs is 20-30 times as much as the average for all defects. Also, over 80% of PMCD-contained defect-prone components still remain defect-prone in successive phases or releases. These findings support the overall hypothesis strongly. We compare our results, where possible, to those of other researchers and discuss the implications on maintenance processes and tools.

Trusted resource dissemination over Internet is still an open problem. However, it is crucial to the success of Internet-based or Internetware systems. We propose an approach that supports trusted resource dissemination between Internetware nodes. In this paper, we focus on an evidence-based trustworthiness-assurance mechanism in the approach. An architecture and a protocol that enforces this approach in Internetware systems are also described.

This article introduces a formal study on access-unrestricted data anonymity. It includes four aspects: (1) analyzes the impacts of anonymity on data usability; (2) quantitatively measures privacy disclosure risks in practical environment; (3) discusses the factors resulting in privacy disclosure; and (4) proposes the improved anonymity solutions within typical k-anonymity model, which can effectively prevent privacy disclosure that is related with the published data properties, anonymity principles, and anonymization rules. With the experiments, the authors have proven the existence of these potential privacy inference violations as well as the enhanced privacy effect by the new anti-inference policies for access-unrestricted data publication.

Resource management continuity is indispensable against illegal resource dissemination and usage in open environment, which should be guaranteed by an effective constraint management mechanism. In detail, it includes two requirements, (1) guaranteeing resource dissemination continuability and purpose-consistency on the dissemination topology, and (2) allowing more-to-more dissemination relation with multiple dissemination policies available on the extended topology for more complicated applications. As we observed, the existed work cannot capture them satisfyingly. We propose constraint inheritance relation (CIR) on a dynamic dissemination topology to specify the continuity of constraint management to capture the first requirement while extend the previous one-to-one dissemination to capture the second. The policy compatibility is maintained while multiple policies are available. We take it into secure resource management (SRM) model for managing the complicated dissemination and usage constraints on diverse resources in dynamic dissemination transaction context. The result proves its feasibility and efficiency.