IUSB Computer and Information Sciences faculty publications and conference presentations
Permanent link for this collectionhttps://hdl.handle.net/2022/19838
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Item The Coevolution of Mobile OS User Market and Mobile Application Developer Community(Compusoft, 2013) Liguo, YuMobile computing is becoming increasingly popular. Accordingly, mobile OS (operating systems) are becoming standard platforms for regular computer and phone users. This paper studies the evolution and the current status of mobile OS user market and mobile application developer community. In particular, we study how smartphone mobile OS user market coevolves with its application developer community. Through this study, we highlight the symbiosis relations between mobile OS user market and mobile apps developer community.Item Multi-Country Analysis of E-commerce Adoption: The Impact of National Culture and Economic Development(Association for Information Systems, 2021) Merhi, Mohammad I.Background: The effect of national culture on e-commerce adoption and usage has yet to be thoroughly examined. This multi-country study examines the influence of Hofstede’s cultural dimensions on e-commerce adoption. It also explores the moderating effect of economic development on the relationships between national culture factors and e-commerce adoption. Method: Secondary data, collected from reputable organizations on sixty countries, are used to test the hypotheses. Correlation, linear regression, cluster analysis, and ANOVA were used to assess the hypotheses presented in the model. Results: The data supported our hypotheses on the direct relationships between national culture factors namely power distance, individualism, long term orientation, and indulgence, and e-commerce adoption. The regression analysis showed that individualism is the most important of all culture factors. The results also indicated that power distance and individualism have different impact on e- commerce adoption, depending on the level of economic development. Conclusions: This study contributes to the growing empirical base of literature on e-commerce and national culture. It validated the importance of a cultural perspective in explaining e-commerce adoption at the national level. It also demonstrated the importance of economic development and its role in shaping the relationships between national culture and e-commerce. Keywords: E-Commerce Adoption, National Culture, Cross-Country, Indulgence, Economic Development.Item The Time Complexity of A* with Approximate Heuristics on Multiple-Solution Search Spaces(AI Access Foundation, 2012) Dinh, Hang; Dinh, Hieu; Michel, Laurent; Russell, AlexanderWe study the behavior of the A* search algorithm when coupled with a heuristic h satisfying (1 - ∈1) h* ≤ h ≤ (1 + ∈2)h*, where ∈1, ∈2 2 [0; 1) are small constants and h* denotes the optimal cost to a solution. We prove a rigorous, general upper bound on the time complexity of A* search on trees that depends on both the accuracy of the heuristic and the distribution of solutions. Our upper bound is essentially tight in the worst case; in fact, we show nearly matching lower bounds that are attained even by non-adversarially chosen solution sets induced by a simple stochastic model. A consequence of our rigorous results is that the effective branching factor of the search will be reduced as long as ∈1 + ∈2 < 1 and the number of near-optimal solutions in the search tree is not too large. We go on to provide an upper bound for A* search on graphs and in this context establish a bound on running time determined by the spectrum of the graph. We then experimentally explore to what extent our rigorous upper bounds predict the behavior of A* in some natural, combinatorially-rich search spaces. We begin by applying A* to solve the knapsack problem with near-accurate admissible heuristics constructed from an efficient approximation algorithm for this problem. We additionally apply our analysis of A* search for the partial Latin square problem, where we can provide quite exact analytic bounds on the number of near-optimal solutions. These results demonstrate a dramatic reduction in effective branching factor of A* when coupled with near-accurate heuristics in search spaces with suitably sparse solution sets.Item Maintainability of the Kernels of Open-Source Operating Systems: A comparison of Linux to FreeBSD, NetBSD, and OpenBSD(Elsevier, 2006) Yu, Liguo; Schach, Stephen R.; Chen, Kai; Heller, Gillian Z.; Offutt, Jeff, 1961-We compared and contrasted the maintainability of four open-source operating systems: Linux, FreeBSD, NetBSD, and OpenBSD. We used our categorization of common coupling in kernel-based software to highlight future maintenance problems. An unsafe definition is a definition of a global variable that can affect a kernel module if that definition is changed. For each operating system we determined a number of measures, including the number of global variables, the number of instances of global variables in the kernel and overall, as well as the number of unsafe definitions in the kernel and overall. We also computed the value of each our measures per kernel KLOC and per KLOC overall. For every measure and every ratio, Linux compared unfavorably to FreeBSD, NetBSD, and OpenBSD. Accordingly, we are concerned about the future maintainability of Linux.Item Using Peer Comparison Approaches to Measure Software Stability(Caomei Publishers, 2018-04-30) Yu, LIguo; Li, Yingmei; Ramaswamy, SriniSoftware systems must change to adapt to new functional requirements and new nonfunctional requirements. This is called software revision. However, not all the modules within the system need to be changed during each revision. In this paper, we study how frequently each module is modified. Our study is performed through comparing the stability of peer software modules. The study is performed on six open-source Java projects: Ant, Flow4j, Jena, Lucence, Struct, and Xalan, in which classes are identified as basic software modules. Our study shows (1) about half of the total classes never changed; (2) frequent changes occur to small number of classes; and (3) the number of changed classes between current release and next release has no significant relations with the time duration between current release and next release. Keywords: software evolution; software revision; software stability; class stability; open-source project; Java classItem Ubiquitous Nature of Event-Driven Approaches: A Retrospective View(Internat. Begegnungs- und Forschungszentrum für Informatik, 2007) Chakravarthy, Sharma; Adaikkalavan, RamanThis paper retrospectively analyzes the progress of event-based capability and their applicability in various domains. Although research on event-based approaches started in a humble manner with the intention of introducing triggers in database management systems for monitoring application state and to automate applications by reducing/eliminating user intervention, currently it has become a force to reckon with as it finds use in many diverse domains. This is primarily due to the fact that a large number of real-world applications are indeed event-driven and hence the paradigm is apposite. In this paper, we briefly overview the development of the ECA (or event-condition-action) paradigm. We briefly discuss the evolution of the ECA paradigm (or active capability) in relational and Object-oriented systems. We then describe several diverse applications where the ECA paradigm has been used effectively. The applications range from customized monitoring of web pages to specification and enforcement of access control policies using RBAC (role-based access control). The multitude of applications clearly demonstrate the ubiquitous nature of event-based approaches to problems that were not envisioned as the ones where the active capability would be applicable. Finally, we indicate some future trends that can benefit from the ECA paradigm.Item Secure Shared Continuous Query Processing(Association for Computing Machinery, 2011-03) Adaikkalavan, Raman; Perez, ThomasData Stream Management Systems (DSMSs) are being used in diverse application domains (e.g., stock trading), however, the need for processing data securely is becoming critical to several stream applications (e.g., patient monitoring). In this paper, we introduce a novel three stage (pre-processing, query processing, and post-processing) framework to enforce access control in DSMSs. As opposed to existing systems, our framework allows continuous queries to be shared when they have same or different privileges, does not modify the query plans, introduces no new security operators, and checks a tuple only once irrespective of the number of active continuous queries. In addition, it does not affect the DSMS quality of service improvement mechanisms as query plans are not modified. We discuss the prototype implementation using the MavStream Data Stream Management System. Finally, we discuss experimental evaluations to demonstrate the low overhead and feasibility of our approach.Item Fair Bandwidth Sharing and Delay Differentiation: Joint Packet Scheduling With Buffer Management(Computer Communications, 2008) Zhou, Xiaobo, 1973-; Ippoliti, Dennis; Zhang, LiqiangPacket delay and bandwidth are two important metrics for measuring quality of service (QoS) of Internet services. Traditionally, packet delay differentiation and fair bandwidth sharing are studied separately. In this paper, we first propose a generalized model for providing fair bandwidth sharing with delay differentiation, namely FBS-DD, at the same time. It essentially aims to provide multi-dimensional proportional differentiation with respect to both QoS metrics. We design size-based packet scheduling schemes that take both packet delay and packet size into scheduling considerations, without assuming admission control or policing. Furthermore, we propose a PID control-theoretic buffer management scheme. The packet scheduling with buffer management approach provides delay and bandwidth differentiation in an integrated way, while existing approaches consider delay and loss rate differentiation as orthogonal issues. It enhances the flexibility of network resource management and multi-dimensional QoS provisioning. It is capable of self-adapting to varying workloads from different classes, which automatically builds a firewall around aggressive clients and hence protects network resources from saturation. Extensive simulation results by the use of trace files demonstrate that the packet scheduling schemes can provide predictable fair bandwidth sharing with delay differentiation at various situations. The control-theoretic buffer management scheme further improves the controllability. Keywords: Proportional differentiation; Fair bandwidth sharing; Multi-dimensional; Quality of service; Packet scheduling; Buffer management; Feedback controlItem Common Coupling as a Measure of Reuse Effort in Kernel-Based Software with Case Studies on the Creation of MkLinux and Darwin(Journal of the Brazilian Computer Society, 2008) Yu, LiguoAn obstacle to software reuse is the large number of major modifications that frequently have to be made as a consequence of dependencies within the reused software components. In this paper, common coupling is categorized and used as a measure of the dependencies between software components. We compared common coupling in three operating systems, Linux, FreeBSD, and Mach, and related it to the reuse effort of these systems. The measure is evaluated by studying the creation of two operating systems, MkLinux which is based on the reuse of Linux and Mach, and Darwin which is based on the reuse of FreeBSD and Mach. We conclude that the way that common coupling is implemented in Linux kernel induces large dependencies between software components, which required more effort in order to be reused to produce MkLinux, while the common coupling implemented in the Mach and FreeBSD kernels induces few dependencies between software components, which required less effort in order to be reused to produce Darwin. Keywords: Reuse, common coupling, kernel-based software, MkLinux, Darwin