A protocol for machine-readable cache policies in OGC web services: Application to the EuroGeoSource information system

An efficient access to the contents provided through OGC web services, widely used in environmental information systems, is usually achieved by means of caching strategies. Service-owners may be interested in expressing the conditions required to allow for this. If these conditions are expressed in a machine-readable way, automatic harvesters can be programmed to follow them.This paper proposes a protocol to specify and follow cache policies for OGC web services expressed in a machine-readable language. A preliminary implementation of this protocol has been tested in the EuroGeoSource project, where a number of Web Feature Services providing mineral deposits and energy resources are periodically cached to improve the efficiency and availability of several applications. The protocol addresses a nowadays common case, and can possibly be extended to allow for more detailed policies. Further work will help to determine how it could be integrated into a full Digital Rights Management system.     

Virtual Customer Assistants in finance: From state of the art and practices to design guidelines

Virtual Customer Assistants (VCAs) are revolutionizing the way users interact with machines. VCAs allow a far more natural interaction, and are gaining an increasingly large role in customer service. The financial domain is especially susceptible of this change, because customer care is of paramount importance. Furthermore, VCAs have the potential of supporting customers in performing routine operations such as money transfers, or in more complex decision-making operations such as trading stocks, both of which require that VCAs display strong reliability. This survey has a two-fold goal. First, we perform an analysis of the state of the art and practices of VCAs in the financial domain. Second, we provide a sort of toolbox that collects the best practices for designing and developing a VCA in the financial domain, guaranteeing a high-quality user experience.     

Supporting science learning in linguistically diverse classrooms: Factors related to the use of bilingual content in a computer-based learning environment

Computer-based learning environments (CBLEs) are a promising means to support language minority (LMi) students in acquiring knowledge and skills through the integration of authentic support in their home language. This study aimed to determine the use of scientific bilingual content offered to fourth-grade students (n = 250) in the CBLE E-Validiv and to identify both student and classroom characteristics related to this use. All the content in E-Validiv is accessible in the language of instruction and one of six other languages. For LMi students, the other language is set to their home language. Multilevel hierarchical regression analyses show that especially LMi students who assess themselves as highly proficient in their home language use the content more in the other language than language majority students. However, even LMi students focus mainly on content in the language of instruction, which indicates that they particularly apply their home language to support their learning process in the language of instruction. Additionally, students who perform higher on science subjects access content more in the language of instruction. The presence of linguistic diversity in the classroom and the positive use of linguistic diversity by the teacher do not seem to matter. The theoretical and practical implications are discussed.     

Efficient resource management in the cloud: From simulation to experimental validation using a low-cost Raspberry Pi testbed

Within the context of cloud computing, efficient resource management is of great importance as it can result in higher scalability and significant energy and cost reductions over time. Because of the high complexity and costs of cloud environments, however, newly developed resource allocation strategies are often only validated by means of simulations, for example, by using CloudSim or custom-developed simulation tools. This article describes a general approach for the validation of cloud resource allocation strategies, illustrating the importance of experimental validation on physical testbeds. Furthermore, the design and implementation of Raspberry Pi as a Service (RPiaaS), a low-cost embedded testbed built using Raspberry Pi nodes, is presented. RPiaaS aims to facilitate the step from simulations toward experimental evaluations on larger cloud testbeds and is designed using a microservice architecture, where experiments and all required management services are running inside containers. The performance of the RPiaaS testbed is evaluated using several benchmark experiments. The obtained results not only illustrate that the overhead of both using containers and running the required RPiaaS services is minimal but also provide useful insights for scaling up experiments between the Raspberry Pi testbed and a larger more traditional cloud testbed. The introduced validation approach is then illustrated using a case study focusing on the allocation of hierarchically structured tenant data. The results obtained through simulations are compared to the experimental results. The RPiaaS testbed proved to be a very useful tool for the initial experimental validation before moving the experiments to a large-scale testbed.     

REDOM: an OO language to define and on-line manipulate regulations in the resource (re)scheduling problem

In the class of (re)scheduling problems where humans constitute the main resource, the scheduling process is influenced by a great number of complex and frequently changing regulations. The complexity and the dynamic nature of these regulations impose the need for an efficient, flexible and user-friendly way to express and manage them. A solution to this problem, in the form of an object-oriented high-level language with semantics highly-tailored to the user needs, is presented. The language, called REDOM, can be applied to different scheduling application domains with a minimum degree of effort, because it is based on a generic meta-model of the resource scheduling problem. An application programming interface facilitates REDOM integration into existing scheduling systems. REDOM is currently being utilised by the DAYSY resource management system, that is implemented as a constraint satisfaction system based on a partial test-and-generate approach. The combination of REDOM and CHIP (Constraint Handling In Prolog), which was used for the implementation of the solution generation subsystem, resulted in a highly-efficient and flexible (re)scheduling system, well-accepted by users. © 1997 John Wiley & Sons, Ltd.