1,720,977 research outputs found
Proc. of 1st International Workshop on System Support for Future Mobile Computing Applications
No full textImproving dependability of Service Oriented Architectures for Pervasive Computing
No full textService oriented programming - which combines distributed object computing, component-based and Web-based concepts - has recently emerged as a promising approach to develop dynamic and heterogeneous service provision environments. Such systems are referenced in literature as service oriented architectures. Classic strategies to address dependability in distributed object computing middleware may not be straightforwardly applied to service oriented architectures (SOAs) for pervasive computing, since they operate in quite different contexts compared to traditional DOC middleware. In this paper, our focus is on dependability issues of SOAs. In particular, we identify dependability requirements of such systems during their life cycle showing how these requirements may change depending on the time phase (discovery, lookup, setup, delivery). We also explore the suitability of Jini technology as an enabling infrastructure to improve availability and reliability, describing both the benefits and drawbacks of a Jini-based solution in the context of a case study application, namely PRINCEPS
An Architecture for Providing Java Applications with Indoor and Outdoor Hybrid Location Sensing
No full textThis paper presents a software architecture that enables either the combined and separate use of indoor and outdoor location-sensing technologies. The architecture has been implemented in compliance with the specifications of the Location API for Java. It is explicitly designed to provide applications with a hybrid location information, i.e., it allows to identify the terminal position among a known set of indoor or outdoor zones (e.g., building rooms, or predefined outdoor areas). The architecture relies on a low-cost, easily deployable and tunable indoor positioning infrastructure, and on existing outdoor location sensing infrastructures as well. In this paper we specifically describe the design and the implementation of a prototype based on Bluetooth and GPS technologies
Securing services in nomadic computing environments
No full textThis work addresses the existing research gap regarding the security of service oriented architectures and their integration in the context of nomadic computing. The state of the art of Service Oriented Architectures (SOAs) is thoroughly investigated to understand what secure service provision means for different SOAs and whether an established notion of secure SOA existed. Based on the analysis of existing SOAs, we define a set of requirements for securing services among different nomadic computing domains. Such requirements concern the security of service registration and that of the discovery and delivery phases. The surveyed SOAs are then evaluated in the light of the defined requirements, revealing interesting observations about how current SOAs address security issues. The second part of this work addresses the research issue of achieving secure service provision in a nomadic computing environment characterized by a number of heterogeneous service oriented architectures. A solution is presented in the form of an architectural model, named Secure Nomadic Computing Architecture. The model relies on a novel three-phase discovery-delivery protocol which allows the enforcement of a number of security requirements, identified as a result of the first part of the work. Finally, we present an exemplary implementation of the proposed architectural model developed within the context of a distributed management information system for the discovery of digital educational content
Modeling and Detecting Failures in Next-generation Distributed Multimedia Applications
No full textIn this paper we investigate dependability issues of next-generation distributed multimedia applications. Examples of such applications are autonomous vehicle control, tele-medicine, and audio/video control. For these applications the quality of the delivered multimedia data is a critical factor. According to the ITU-T (working group SG 12), the quality of a multimedia service as perceived by end-users is defined by three parameters: delay, delay variation, and information loss. It is paramount to formalize the concept of a failure from the user's perspective. This paper defines the correctness of a multimedia service as a function of temporal distributions of the user-related parameters. It proposes a strategy for modeling and detecting failures of the considered applications. In particular, the detection process is based on error filtering functions. We show that the combination of threshold-based mechanisms is suitable for implementing an efficient detection strategy. We also evaluate the effectiveness of the proposed mechanism both by simulations and by experiments performed on a prototype. Such a prototype is tested with respect to a case study application, consisting of distributed remote-control based on RTP/RTCP standard streaming protocols
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
A Strategy for Application-Transparent Integration of Nomadic Computing Domains
No full textNomadic computing environments are composed of heterogeneous mobile computing domains. Unfortunately, the service discovery platforms suitable for each domain are scarcely interoperable with each other. This work proposes a novel architecture to mitigate the diversity of service representations, technologies, and interaction models of current service discovery platforms. The ultimate goal is to allow nomadic users to discover services across domain borders. The proposed architecture is composed of discovery agents that connect domains into a single logical domain, and allow services to be imported and exported between heterogeneous domains
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
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