27 research outputs found

    Linux XIA: an interoperable meta network architecture

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    With the growing number of clean-slate redesigns of the Internet, the need for a medium that enables all stakeholders to participate in the realization, evaluation, and selection of these designs is increasing. We believe that the missing catalyst is a meta network architecture that welcomes most, if not all, clean-state designs on a level playing field, lowers deployment barriers, and leaves the final evaluation to the broader community. This thesis presents the eXpressive Internet (Meta) Architecture (XIA), itself a clean-slate design, as well as Linux XIA, a native implementation of XIA in the Linux kernel, as a candidate. As a meta network architecture, XIA is highly flexible, leaving stakeholders to choose an expressive set of network principals to instantiate a given network architecture within the XIA framework. Central to XIA is its novel, non-linear network addressing format, from which derive key architectural features such as evolvability, intrinsically secure identifiers, and a low degree of principal isolation. XIP, the network layer protocol of XIA, forwards packets by navigating these structured addresses and delegating the decision-making and packet processing to appropriate principals, accordingly. Taken together, these mechanisms work in tandem to support a broad spectrum of interoperable principals. We demonstrate how to port four distinct and unrelated network architectures onto Linux XIA, none of which were designed for interoperability with this platform. We then show that, notwithstanding this flexibility, Linux XIA's forwarding performance remains comparable to that of the more mature legacy TCP/IP stack implementation. Moreover, the ported architectures, namely IP, Serval, NDN, and ANTS, empower us to present a deployment plan for XIA, to explore design variations of the ported architectures that were impossible in their original form due to the requirement of self-sufficiency that a standalone network architecture bears, and to substantiate the claim that XIA readily supports and enables network evolution. Our work highlights the benefits of specializing network designs that XIA affords, and comprises instructive examples for the network researcher interested in design and implementation for future interoperability

    Embedding Globally-Routable Internet Addresses Considered Harmful

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    Software Defined Application Delivery Networking

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    In this thesis we present the architecture, design, and prototype implementation details of AppFabric. AppFabric is a next generation application delivery platform for easily creating, managing and controlling massively distributed and very dynamic application deployments that may span multiple datacenters. Over the last few years, the need for more flexibility, finer control, and automatic management of large (and messy) datacenters has stimulated technologies for virtualizing the infrastructure components and placing them under software-based management and control; generically called Software-defined Infrastructure (SDI). However, current applications are not designed to leverage this dynamism and flexibility offered by SDI and they mostly depend on a mix of different techniques including manual configuration, specialized appliances (middleboxes), and (mostly) proprietary middleware solutions together with a team of extremely conscientious and talented system engineers to get their applications deployed and running. AppFabric, 1) automates the whole control and management stack of application deployment and delivery, 2) allows application architects to define logical workflows consisting of application servers, message-level middleboxes, packet-level middleboxes and network services (both, local and wide-area) composed over application-level routing policies, and 3) provides the abstraction of an application cloud that allows the application to dynamically (and automatically) expand and shrink its distributed footprint across multiple geographically distributed datacenters operated by different cloud providers. The architecture consists of a hierarchical control plane system called Lighthouse and a fully distributed data plane design (with no special hardware components such as service orchestrators, load balancers, message brokers, etc.) called OpenADN . The current implementation (under active development) consists of ~10000 lines of python and C code. AppFabric will allow applications to fully leverage the opportunities provided by modern virtualized Software-Defined Infrastructures. It will serve as the platform for deploying massively distributed, and extremely dynamic next generation application use-cases, including: Internet-of-Things/Cyber-Physical Systems: Through support for managing distributed gather-aggregate topologies common to most Internet-of-Things(IoT) and Cyber-Physical Systems(CPS) use-cases. By their very nature, IoT and CPS use cases are massively distributed and have different levels of computation and storage requirements at different locations. Also, they have variable latency requirements for their different distributed sites. Some services, such as device controllers, in an Iot/CPS application workflow may need to gather, process and forward data under near-real time constraints and hence need to be as close to the device as possible. Other services may need more computation to process aggregated data to drive long term business intelligence functions. AppFabric has been designed to provide support for such very dynamic, highly diversified and massively distributed application use-cases. Network Function Virtualization: Through support for heterogeneous workflows, application-aware networking, and network-aware application deployments, AppFabric will enable new partnerships between Application Service Providers (ASPs) and Network Service Providers (NSPs). An application workflow in AppFabric may comprise of application services, packet and message-level middleboxes, and network transport services chained together over an application-level routing substrate. The Application-level routing substrate allows policy-based service chaining where the application may specify policies for routing their application traffic over different services based on application-level content or context. Virtual worlds/multiplayer games: Through support for creating, managing and controlling dynamic and distributed application clouds needed by these applications. AppFabric allows the application to easily specify policies to dynamically grow and shrink the application\u27s footprint over different geographical sites, on-demand. Mobile Apps: Through support for extremely diversified and very dynamic application contexts typical of such applications. Also, AppFabric provides support for automatically managing massively distributed service deployment and controlling application traffic based on application-level policies. This allows mobile applications to provide the best Quality-of-Experience to its users without This thesis is the first to handle and provide a complete solution for such a complex and relevant architectural problem that is expected to touch each of our lives by enabling exciting new application use-cases that are not possible today. Also, AppFabric is a non-proprietary platform that is expected to spawn lots of innovations both in the design of the platform itself and the features it provides to applications. AppFabric still needs many iterations, both in terms of design and implementation maturity. This thesis is not the end of journey for AppFabric but rather just the beginning

    Engineering a semantic web trust infrastructure

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    The ability to judge the trustworthiness of information is an important and challenging problem in the field of Semantic Web research. In this thesis, we take an end-to-end look at the challenges posed by trust on the Semantic Web, and present contributions in three areas: a Semantic Web identity vocabulary, a system for bootstrapping trust environments, and a framework for trust aware information management. Typically Semantic Web agents, which consume and produce information, are not described with sufficient information to permit those interacting with them to make good judgements of trustworthiness. A descriptive vocabulary for agent identity is required to enable effective inter agent discourse, and the growth of trust and reputation within the Semantic Web; we therefore present such a foundational identity ontology for describing web-based agents.It is anticipated that the Semantic Web will suffer from a trust network bootstrapping problem. In this thesis, we propose a novel approach which harnesses open data to bootstrap trust in new trust environments. This approach brings together public records published by a range of trusted institutions in order to encourage trust in identities within new environments. Information integrity and provenance are both critical prerequisites for well-founded judgements of information trustworthiness. We propose a modification to the RDF Named Graph data model in order to address serious representational limitations with the named graph proposal, which affect the ability to cleanly represent claims and provenance records. Next, we propose a novel graph based approach for recording the provenance of derived information. This approach offers computational and memory savings while maintaining the ability to answer graph-level provenance questions. In addition, it allows new optimisations such as strategies to avoid needless repeat computation, and a delta-based storage strategy which avoids data duplication.<br/

    Descubrimiento din谩mico de servidores basado en informaci贸n de localizaci贸n usando una tabla de Hash distribuida balanceada

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    The current Internet includes a large number of distributed services. In order to guarantee the QoS of the communications in these services, a client has to select a close-by server with enough available resources. To achieve this objective, in this Thesis, we propose a simple and practical solution for Dynamic and Location Aware Server Discovery based on a Distributed Hash Table (DHT). Specifically, we decide to use a Chord DHT system (although any other DHT scheme can be used). In more detail, the solution works as follows. The servers offering a given service S form a Chord-like DHT. In addition, they register their location (topological and/or geographical) information in the DHT. Each client using the service S is connected to at least one server from the DHT. Eventually, a given client C realizes that it is connected to a server providing a bad QoS, then, it queries the DHT in order to find an appropriate server (i.e. a close-by server with enough available resources). We define 11 design criteria, and compare our solution to the Related Work based on them. We show that our solution is the most complete one. Furthermore, we validate the performance of our solution in two different scenarios: (i) NAT Traversal Server Discovery and (ii) Home Agent Discovery in Mobile IP scenarios. The former serves to validate our solution in a highly dynamic environment whereas the latter demonstrates the appropriateness of our solution in more classical environments where the servers are typically always-on hosts. The extra overhead suffered from the servers involved in our system comes from their participation in the Chord DHT. Therefore, it is critical to fairly balance the load among all the servers. In our system as well as in other P2P systems (e.g. P2PSIP) the stored objects are small, then routing dominates the cost of publishing and retrieving objects. Therefore, in the second part of this Thesis, we address the issue of fairly balancing the routing load in Chord DHTs. We present an analytical model to evaluate the routing fairness of Chord based on the well accepted Jain鈥檚 Fairness Index (FI). Our model shows that Chord performs poorly. Following this observation, we propose a simple enhancement to the Chord finger selection algorithm with the goal of mitigating this effect. The key advantage of our proposal as compared to previous approaches is that it adds a neglible overhead to the basic Chord algorithm. We validate the goodness of the proposed solution analytically and by large scale simulations.-------------------------------------------------------------------------------------------------------------------------------------------------------------En los 煤ltimos a帽os un gran n煤mero de servicios distribu铆dos han aparecido en Internet. Para garantizar la Calidad de Servicio de las comunicaciones en estos servicios sus clientes deben conectarse a un servidor cercano con suficientes recursos disponibles. Para alcanzar este objetivo, en esta Tesis, se propone una soluci贸n simple y pr谩ctica para el Descubrimiento Din谩mico de Servidores basado en Informaci贸n de Localizaci贸 usando una Tabla de Hash Distribu铆da (DHT). En concreto, hemos decidido usar una DHT de tipo Chord (aunque cualquier otro tipo de DHT puede usarse). A continuaci贸n describimos brevemente nuestra soluci贸n. Los servidores que ofrecen un servicio espec铆fico S forman una DHT tipo Chord donde registran su informaci贸n de localizaci贸n (topol贸gica y/o geogr谩fica). Cada cliente que usa el servicio S est谩 conectado al menos a un servidor de la DHT. En caso de que un cliente C perciba que el servidor al que est谩 conectado est谩 ofreciendo una mala Calidad de Servicio, C consulta la DHT para encontrar un servidor m谩s apropiado (p.ej. un servidor cercano con suficientes recursos disponibles). En la Tesis se definen 11 criterios de dise帽o y se compara nuestra soluci贸n con las soluciones existentes en base a ellos, demostrando que la nuestra es la soluci贸n m谩s completa. Adem谩s, validamos el rendimiento de nuestra soluci贸n en dos escenarios diferentes: (i) Descubrimiento de Servidores para atravesar Traductores de Direcciones de Red (NATs) y (ii) Descubrimiento de Agentes Hogar (HAs) en escenarios de Movilidad IP. El primero sirve para validar el rendimiento de nuestra soluci贸n en escenarios altamente din谩micos mientras que el segundo demuestra la validez de la soluci贸n en un escenario m谩s cl谩sico donde los servidores son m谩quinas que est谩n ininterrumpidamente funcionando. Los servidores involucrados en nuestro sistema sufren una sobrecarga debido a su participaci贸n en la DHT tipo Chord. Desafortunadamente, esta sobrecarga es inherente al sistema anteriormente descrito y no se puede eliminar. En cambio lo que s铆 podemos hacer es balancear la carga de la manera m谩s justa posible entre todos los servidores. En nuestro sistema, al igual que en otros sistemas P2P (p.ej. P2PSIP) los objetos almacenados tienen un tama帽o peque帽o, produciendo que sea la tarea de enrutamiento la que domina el coste de publicar y obtener objetos. Por lo tanto, en la segunda parte de esta Tesis abordamos el reparto equilibrado de la carga de enrutamiento en DHTs tipo Chord. En primer lugar, definimos un modelo anal铆tico para evaluar el reparto de la carga de enrutamiento entre los nodos que forman una DHT tipo Chord. Para ello nos basamos en una m茅trica aceptada por la comunidad investigadora como es el Jain鈥檚 Fairness Index (FI). El modelo resultante demuestra que Chord tiene un rendimiento pobre en el reparto justo de la carga de enrutamiento. Bas谩ndonos en esta observaci贸n proponemos una modificaci贸n simple al algoritmo de selecci贸n de punteros de Chord para mejorar el reparto de la carga de enrutamiento. La ventaja fundamental de nuestra soluci贸n en comparaci贸n con otras propuestas anteriores es que nuestra soluci贸n a帽ade un coste despreciable al algoritmo b谩sico de Chord. Finalmente, validamos el rendimiento de nuestra soluci贸n anal铆ticamente y por medio de simulaciones a gran escala

    Earth Observation Open Science and Innovation

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    geospatial analytics; social observatory; big earth data; open data; citizen science; open innovation; earth system science; crowdsourced geospatial data; citizen science; science in society; data scienc
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