40 research outputs found
mBlog: a mobile information service
No full textEasy-to-use Web sites, called "weblogs" or "blogs" are the latest massive Internet phenomenon. mBlog, developed by SICS in collaboration with Ericsson, takes blogs a step further by adding a mobility component.</p
DIVE on the internet [Elektronisk resurs]
No full textThis dissertation reports research and development of a platform for Collaborative Virtual Environments (CVEs). It has particularly focused on two major challenges: supporting the rapid development of scalable applications and easing their deployment on the Internet. This work employs a research method based on prototyping and refinement and promotes the use of this method for application development. A number of the solutions herein are in line with other CVE systems. One of the strengths of this work consists in a global approach to the issues raised by CVEs and the recognition that such complex problems are best tackled using a multi-disciplinary approach that understands both user and system requirements. CVE application deployment is aided by an overlay network that is able to complement any IP multicast infrastructure in place. Apart from complementing a weakly deployed worldwide multicast, this infrastructure provides for a certain degree of introspection, remote controlling and visualisation. As such, it forms an important aid in assessing the scalability of running applications. This scalability is further facilitated by specialised object distribution algorithms and an open framework for the implementation of novel partitioning techniques. CVE application development is eased by a scripting language, which enables rapid development and favours experimentation. This scripting language interfaces many aspects of the system and enables the prototyping of distribution-related components as well as user interfaces. It is the key construct of a distributed environment to which components, written in different languages, connect and onto which they operate in a network abstracted manner. The solutions proposed are exemplified and strengthened by three collaborative applications. The Dive room system is a virtual environment modelled after the room metaphor and supporting asynchronous and synchronous cooperative work. WebPath is a companion application to a Web browser that seeks to make the current history of page visits more visible and usable. Finally, the London travel demonstrator supports travellers by providing an environment where they can explore the city, utilise group collaboration facilities, rehearse particular journeys and access tourist information data.</p
DIVE: Communication Architecture and Programming Model
No full textThis article presents the Distributed Interactive Virtual Environment (DIVE) system, a software architecture for the realization and implementation of wide-area Internet-based multi-user virtual environments. Over the years, DIVE has evolved into a generic tool that supports a wide range of applications and situations. The article focuses on the networking aspects that allow deployment of multi-user virtual environments on the Internet. Additionally, it presents the palette of programming interfaces and techniques offered by the system. This is highlighted by some example applications. Our experience has proven that DIVE's ability to mix interfaces has made it a system of choice for the implementation of distributed applications.</p
Faster Rates for Compressed Federated Learning with Client-Variance Reduction
No full textDue to the communication bottleneck in distributed and federated learning
applications, algorithms using communication compression have attracted
significant attention and are widely used in practice. Moreover, the huge
number, high heterogeneity and limited availability of clients result in high
client-variance. This paper addresses these two issues together by proposing
compressed and client-variance reduced methods COFIG and FRECON. We prove an
bound on the number of communication rounds of COFIG in the nonconvex setting,
where is the total number of clients, is the number of clients
participating in each round, is the convergence error, and
is the variance parameter associated with the compression operator. In case of
FRECON, we prove an bound on the
number of communication rounds. In the convex setting, COFIG converges within
communication rounds, which, to the
best of our knowledge, is also the first convergence result for compression
schemes that do not communicate with all the clients in each round. We stress
that neither COFIG nor FRECON needs to communicate with all the clients, and
they enjoy the first or faster convergence results for convex and nonconvex
federated learning in the regimes considered. Experimental results point to an
empirical superiority of COFIG and FRECON over existing baselines.Comment: Accepted by SIAM Journal on Mathematics of Data Science (SIMODS
Construction of collaborative virtual environments
No full textIn this chapter, we give an overview of some of the issues that face programmers and designers when building collaborative virtual environments (CVEs). We do this by highlighting three aspects of CVE system software: the environment model (data structures, behaviour description) that the system provides, the data-sharing mechanism (how he model is shared), and the implementation framework (the structure of a typical client or platform in terms of the services it provides to the user). When a CVE system is designed, choices have to be made for each of these aspects, and this then constrains how the designers and programmers o about constructing the CVE worlds themselves. We present the main body of the overview by using examples that highlight many important differences between CVE systems. We will also relate our discussion to the common topics of network topology and awareness management.</p
Construction of Collaborative Virtual Environments
No full textIn this chapter, we give an overview of some of the issues that face programmers and designers when building collaborative virtual environments (CVEs). We do this by highlighting three aspects of CVE system software: the environment model (data structures, behaviour description) that the system provides, the data-sharing mechanism (how the environment model is shared), and the implementation framework (the structure of a typical client or platform in terms of the services it provides to the user). When a CVE system is designed, choices have to be made for each of these aspects, and this then constrains how the designers and programmers go about constructing the CVE worlds themselves. We present the main body of the overview by using examples that highlight many of the important differences between CVE systems. We will also relate our discussion to the common topics of network topology and awareness management. </jats:p
Technical Challenges in Designing Systems-of-Systems Supporting Vehicle Fleets
No full textAdvances in interconnectivity between vehicles, vehicle fleets and infrastructures led to opportunities of interoperability and systems-of-systems (SoS). Several challenges emerge that put on requirements on dealing with the vast amount of data generated by modern vehicles and their actuation with higher-level commands and controls. They have naturally created opportunities for the development of sophisticated, powerful, generic platforms to support ingestion, storage, processing, management, operation and orchestration of data and processes in SoS. A prominent example is the scenario of vehicle fleets and more precisely, on how to engineer the SoS so that the collaboration among various constituent systems will achieve the SoS goals. Several challenges cap the extent of opportunities, such as determining the business and functional requirements, as well as technical: constructing and operating an independent, scalable, and flexible platform ensuring e.g., privacy and accountability. In this work, we discuss these concerns and challenges from a technical perspective.</p
DIVE: a generic tool for the deployment of shared virtual environments
No full textIn this paper we present the DIVE system (Distributed Interactive Virtual Environment), an architecture and a programming toolkit for the realisation and implementation of wide-area, Internet-based multi-user virtual environments. Along the years, DIVE has evolved into a generic tool that supports a wide range of applications and situations. This paper focuses on the networking and architectural aspects that allow the deployment of multi-user virtual environments on the Internet. Additionally, this paper presents the palette of programming interfaces and techniques that are offered by the system. Our experience has proven that its ability to mix interfaces made it a system of choice for the implementation of distributed applications. We conclude with a selection of applications and how they make use of the networking and programming features of the system
