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A number of distributed applications require communication services with quality of service (QoS) guarantees. Building global-scale distributed systems with predictable properties is one of the great challenges for computer systems engineering in the new century. Work undertaken within the Internet Engineering Task Force has led to the definition of novel architectural models for the Internet with QoS support. According to these models, the network has to be appropriately configured in order to provide applications with the required performance guarantees. In next-generation networks, enabling applications to interact with the underlying QoS services is of primary importance. Hence, several special-purpose application programming interfaces (APIs) have been defined to let applications negotiate QoS parameters across QoS-capable networks. However, so far, none of these APIs are available in different operating environments. We believe that such features should be embedded in programming environments for distributed applications. In this work we present how we included QoS control features in Tcl, a programming language that has been widely adopted for the development of distributed multimedia applications. Our work has led to the implementation of QTcl, an extended Tcl interpreter that provides programmers with a new set of primitives, in full compliance with the standard SCRAPI programming interface for the RSVP protocol. QTcl in highly portable, in that it enables standard QoS negotiation to be performed in a seamless fashion on the most common operating systems. Copyright © 2003 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

The payment channel network (PCN) is an effective off-chain scaling solution widely recognized for reducing operational costs on permissionless blockchains. However, it still faces challenges such as lack of flexibility, channel exhaustion, and poor sustainability. Currently, a separate deposit is required for each payment channel, which locks a significant amount of coins for a longer period. This restricts the ability to move locked coins across their channels off-chain. Additionally, unbalanced (unidirectional) transfers can lead to channel exhaustion, rendering the channel unsustainable. To address these issues, we propose a novel off-chain flexible PCN protocol called Flexichain. Unlike existing approaches, Flexichain allows users to deposit coins per user rather than per channel. This provides flexibility to move coins freely between channels without relying on the blockchain or disrupting the off-chain cycle. Flexichain is proven to be secure under the Universal Composability framework and resistant against channel exhaustion attacks. To assess the performance of Flexichain, we conduct experiments on both on-chain and off-chain operations using snapshots of the Lightning Network. We evaluate the on-chain gas costs, success ratio and success amount of off-chain payments under uniform and skewed payment demands, as well as the computational and communication overheads of the off-chain contracts. [ABSTRACT FROM AUTHOR]

This research work aimed at optimizing tuning parameters for the regulation of speed and power of Francis turbine. Here prototype calculations are used to model the Francis turbine. Here PID controllers are used to optimize the parameters of torque, power and time. Block diagram with control functions of turbine, actuator, generator and PID controller are employed here. Response of tuning of parameters of power and time are noted here for optimal models. Finally slow runner Francis turbine has selected for running with optimal speed and power. [ABSTRACT FROM AUTHOR]

Despite the technological possibilities for portable, personalized, and participatory news use, the public has not turneden massefrom passive receivers who consume news on the producers' terms, into active users who tailor news to fit their personal preferences and practices. Unmistakably, some power has shifted from producers to users, but it is unclear to what extent users actually wish to exert their newfound control. Triangulating the results of in-depth user interviews (24), a user survey (N= 270), production interviews with (chief) editors and policy makers (5), and an inventory of new “news products” on mobile and social media, we explore under which circumstances users want to tailor-make news, and under which circumstances they do not. Our results suggest that users have limited interest in personalizing or participating in news. What they desire in particular is control: to be able to consult all content (including politics, economics, and other important news) whenever and wherever they want it. This does not mean that they will read or click on all or even most of the news, but they want the option to choose without having to choose. [ABSTRACT FROM PUBLISHER]

Distributed research testbeds play a fundamental role in the evaluation of disruptive innovations for the Future Internet. In recent years, the main research funding agencies have promoted several initiatives aimed at designing and building open, large scale, realistic experimental facilities that could be used to evaluate innovative networking architectures, paradigms and services. In this paper, after discussing the main challenges in building such infrastructures, we present how, by leveraging the concept of federation, we managed to introduce a first degree of heterogeneity into PlanetLab Europe, a European testbed federated with PlanetLab, by providing UMTS connectivity to PlanetLab Europe nodes. Our contribution is just a first step of an evolutionary path whose further developments will lead to next generation large-scale heterogeneous testbeds for supporting experimentally-driven research on the Network of the Future (Preliminary results within the same framework of this work have been recently published in Canonico et al. () and Botta et al. ()). [ABSTRACT FROM AUTHOR]

Significant progress has been made in the design and development of Grid middleware which, in its present form, is founded on Web services technologies. However, we argue that present-day Grid middleware is severely limited in supporting projected next-generation applications which will involve pervasive and heterogeneous networked infrastructures, and advanced services such as collaborative distributed visualization. In this paper we discuss a new Grid middleware framework that features (i) support for advanced network services based on the novel concept of pluggable overlay networks, (ii) an architectural framework for constructing bespoke Grid middleware platforms in terms of ‘middleware domains’ such as extensible interaction types and resource discovery. We believe that such features will become increasingly essential with the emergence of next-generation e-Science applications. Copyright © 2005 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

The availability of high-performance networking technologies and processing power allows creation of new multimedia services and applications in broadband integrated services networks. Such new services will be successful only if delivered to end-users at low cost. At present, for wide-area distributed systems, communication has a relevant impact on the overall costs. As a consequence, adequate methodologies for an efficient dimensioning of the network resources need to be devised. Simulation techniques represent a powerful instrument for the analysis and evaluation of real systems. This paper, moving from the definition of mathematical models for VBR video sources, presents the application of a simulation approach to verify the compatibility of the communication load related to a set of video streams with the data transport capability of an existing network architecture for the delivery of video streams, in the case of CBR communication links. [ABSTRACT FROM AUTHOR]

We propose a new application-level clustering algorithm capable of building an overlay spanning tree among participants of large multicast sessions, without any specific help from the network routers. The algorithm and associated protocol are shown to exhibit scalable properties [ABSTRACT FROM PUBLISHER]

Mobile cloud computing (MCC) has recently emerged as a state-of-the-art technology for mobile systems. MCC enables portable and context-aware computation via mobile devices by exploiting virtually unlimited hardware and software resources offered by cloud computing servers. Software architecture helps to abstract the complexities of system design, development, and evolution phases to implement MCC systems effectively and efficiently. This paper aims to identify, taxonomically classify, and systematically map the state of the art on architecting MCC-based software. We have used an evidence-based software engineering (EBSE) approach to conduct a systematic mapping study (SMS) based on 121 qualitatively selected research studies published from 2006 to 2019. The results of the SMS highlight that architectural solutions for MCC systems are mainly focused on supporting (i) software as a service for mobile computing, (ii) off-loading mobile device data to cloud-servers, (iii) internet of things, edge, and fog computing along with various aspects like (iv) security and privacy of mobile device data. The emerging research focuses on the existing and futuristic challenges that relate to MCC-based internet of things (IoTs), mobile-cloud edge systems, along with green and energy-efficient computing. The results of the SMS facilitate knowledge transfer that could benefit researchers and practitioners to understand the role of software architecture to develop the next generation of mobile-cloud systems to support internet-driven computing. [ABSTRACT FROM AUTHOR]