Fine Grained Component Engineering of Adaptive Overlays: Experiences and Perspectives

Recent years have seen significant research being carried out into peer-to-peer (P2P) systems. This work has focused on the styles and applications of P2P computing, from grid computation to content distribution; however, little investigation has been performed into how these systems are built. Component based engineering is an approach that has seen successful deployment in the field of middleware development; functionality is encapsulated in ‘building blocks’ that can be dynamically plugged together to form complete systems. This allows efficient, flexible and adaptable systems to be built with lower overhead and development complexity. This paper presents an investigation into the potential of using component based engineering in the design and construction of peer-to-peer overlays. It is highlighted that the quality of these properties is dictated by the component architecture used to implement the system. Three reusable decomposition architectures are designed and evaluated using Chord and Pastry case studies. These demonstrate that significant improvements can be made over traditional design approaches resulting in much more reusable, (re)configurable and extensible systems

GRIDKIT: Pluggable overlay networks for Grid computing

A `second generation' approach to the provision of Grid middleware is now emerging which is built on service-oriented architecture and web services standards and technologies. However, advanced Grid applications have significant demands that are not addressed by present-day web services platforms. As one prime example, current platforms do not support the rich diversity of communication `interaction types' that are demanded by advanced applications (e.g. publish-subscribe, media streaming, peer-to-peer interaction). In the paper we describe the Gridkit middleware which augments the basic service-oriented architecture to address this particular deficiency. We particularly focus on the communications infrastructure support required to support multiple interaction types in a unified, principled and extensible manner-which we present in terms of the novel concept of pluggable overlay networks

A Perspective on the Future of Middleware-based Software Engineering

International audienceMiddleware is a software layer that stands between the networked operating system and the application and provides well known reusable solutions to frequently encountered problems like heterogeneity, interoperability, security, dependability. Further, with networks becoming increasingly pervasive, middleware appears as a major building block for the development of future software systems. Starting with the impact of pervasive networking on computing models, manifested by now common grid and ubiquitous computing, this paper surveys related challenges for the middleware and related impact on the software development. Indeed, future applications will need to cope with advanced non-functional properties such as contextawareness and mobility, for which adequate middleware support must be devised together with accompanying software development notations, methods and tools. This leads us to introduce our view on next generation middleware, considering both technological advances in the networking area but also the need for closer integration with software engineering best practices, to ultimately suggest middleware-based software processes

D.1.3 – Protocols for emergent localities

GDD_HCERES2020This report presents two contributions that illustrate the potential of emerging-locality protocols in large-scale decentralized systems, in two areas of decentralized social computing: recommendation, and eventual consistency of mutable data structures. The first contribution consists of a framework supporting the development of dynamically adaptive decen-tralised recommendation systems. Decentralised recommenders have been proposed to deliver privacy-preserving, personalised and highly scalable on-line recommendations. Current implementations tend, however, to rely on a hard-wired similarity metric that cannot adapt. This constitutes a strong limitation in the face of evolving needs. Our framework address this through a decentralised form of adaptation, in which individual nodes can independently select, and update their own recommendation algorithm, while still collectively contributing to the overall system's mission. Our second contribution addresses the growing demand for differentiated consistency requirements in large-scale applications. A large number of today's applications rely on Eventual Consistency, a consistency model that emphasizes liveness over safety. Designers generally adopt this consistency model uniformly throughout a distributed system due to its ability to scale as the number of users or devices grows larger. But this clashes with the need for differentiated consistency requirements. In this contribution, we address this need by introducing UPS, a novel consistency mechanism that offers differentiated eventual consistency and delivery speed by working in pair with a two-phase epidemic broadcast protocol. We propose a closed-form analysis of our approach's delivery speed, and we evaluate our complete protocol experimentally on a simulated network of one million nodes. To measure the consistency trade-off, we formally define a novel and scalable consistency metric operating at runtime