10 research outputs found
Using Dedicated and Opportunistic Networks in Synergy for a Cost-effective Distributed Stream Processing Platform
This paper presents a case for exploiting the synergy of dedicated and
opportunistic network resources in a distributed hosting platform for data
stream processing applications. Our previous studies have demonstrated the
benefits of combining dedicated reliable resources with opportunistic resources
in case of high-throughput computing applications, where timely allocation of
the processing units is the primary concern. Since distributed stream
processing applications demand large volume of data transmission between the
processing sites at a consistent rate, adequate control over the network
resources is important here to assure a steady flow of processing. In this
paper, we propose a system model for the hybrid hosting platform where stream
processing servers installed at distributed sites are interconnected with a
combination of dedicated links and public Internet. Decentralized algorithms
have been developed for allocation of the two classes of network resources
among the competing tasks with an objective towards higher task throughput and
better utilization of expensive dedicated resources. Results from extensive
simulation study show that with proper management, systems exploiting the
synergy of dedicated and opportunistic resources yield considerably higher task
throughput and thus, higher return on investment over the systems solely using
expensive dedicated resources.Comment: 9 page
Rule-based expert server system design for multimedia streaming transmission
Ph.DDOCTOR OF PHILOSOPH
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Security Aware Service Composition
Security assurance of Service-Based Systems (SBS) is a necessity and a key challenge in Service Oriented Computing. Several approaches have been introduced in order to take care of the security aspect of SBSs, from the design to the implementation stages. Such solutions, however, require expertise with regards to security languages and technologies or modelling formalisms. Furthermore, existing approaches allow only limited verification of security properties over a service composition, as they focus just on specific properties and require expressing compositions and properties in a model based formalism.
In this thesis we present a unified security aware service composition approach capable of validation of arbitrary security properties. This approach allows SBS designers to build secure applications without the need to learn formal models thanks to security descriptors for services, being they self-appointed or certified by an external third-party.
More specifically, the framework presented in this thesis allows expressing and propagating security requirements expressed for a security composition to requirements for the single activities of the composition, and checking security requirements over security service descriptors. The approach relies on the new core concept of secure composition patterns, modelling proven implications of security requirements within an orchestration pattern. The framework has been implemented and tested extensively in both a SBS design-time and runtime scenario, based respectively on Eclipse BPEL Designer and the Runtime Service Discovery Tool
Enabling architectures for QoS provisioning
Nowadays, new multimedia services have been deployed with stringent requirements for Quality of Service (QoS). The QoS provisioning is faced with the heterogeneity of system components. This thesis presents two research: on architectures for QoS management at the application layer, fulfilled mainly by software components; and on distributed software architectures for routing devices providing desired QoS at the underlying communication layer. At the application layer, the QoS architecture we propose, based on the Quality Driven Delivery (QDD) framework, deals with the increasing amount of QoS information of a distributed system. Based on various QoS information models we define for key actors of a distributed system, a QoS information base is generated using QoS information collecting and analysis tools. To translate QoS information among different components, we propose mechanisms to build QoS mapping rules from statistical data. Experiments demonstrate that efficient QoS decisions can be made effectively regarding the contribution of all system components with the help of the QoS information management system. At the underlying layer, we investigate distributed and scalable software architectures for QoS-enabled devices. Due to the huge volume of traffic to be switched, the traditional software model used for current generation routers, where the control card of the router performs all the processing tasks, is no longer appropriate in the near future. We propose a new scalable and distributed architecture to fully exploit the hardware platforms of the next generation routers, and to improve the quality of routers, particularly with respect to scalability and to a lesser extent to resiliency and availability. Our proposal is a distributed software framework where control tasks are shared among the control and line cards of the router. Specific architectures for routing, signaling protocols and routing table management are developed. We investigate the challenges for such distributed architectures and proposed various solutions to overcome them. Based on a general distributed software framework, an efficient scalable distributed architecture for MPLS/LDP and different scalable distributed schemes for the routing table manager (RTM) are developed. We also evaluate the performance of proposed distributed schemes and discuss where to deploy these architectures depending on the type of routers (i.e., their hardware capacity
Ontologías para servicios web semánticos de información de tráfico: descripción y herramientas de explotación.
RESUMEN
Esta tesis forma parte de los denominados Sistemas Inteligentes de Tráfico (ITS) los
cuales se basan en la aplicación de tecnologías de Telecomunicaciones e Informática
(Telemática) a los sistemas de ayuda al tráfico vial, perteneciendo al dominio Servicios
de Información al Viajero (TIS).
Como se pone de manifiesto, existen algunos problemas derivados del uso de este tipo
de sistemas, desde el punto de vista del usuario, que dan lugar a que éste sea incapaz de
obtener la información clara y precisa correspondiente a sus requerimientos.
Los principales problemas identificados han sido la falta de un vocabulario común de
términos que haga uso de una semántica bien definida que permita obtener el
significado (incluso aquél no explícito) de cada concepto de tráfico vial, así como la
recuperación de información desde distintas fuentes heterogéneas, de una forma
intuitiva y sencilla.
Varios aspectos describen la problemática actual relativos al acceso y distribución de la
información:
1. Un gran volumen de información de tráfico se distribuye entre varios sitios Web.
El principal problema para un usuario que necesita información de este tipo es
encontrar estos sitios Web y además tratar con los diferentes accesos a ésta, así
como sus diferentes formas de presentación.
2. Por otra parte, un usuario puede necesitar información de diferente naturaleza o
tipo, y por lo tanto el almacenaje de toda esta información en un solo sitio Web
no es viable a nivel de costes de almacenamiento ni incluso a nivel de
mantenimiento.
3. El tratamiento de la información no permite realizar inferencias sobre ella de
manera que pueda ser obtenido como resultado, información que a priori no
estuviera explícitamente detallada.
Tras el descubrimiento de la problemática existente y la identificación de elementos que
pudieran solventar esta situación, el presente trabajo se centra en el estudio de los
sistemas ITS orientados a facilitar información de tráfico al usuario, y que a su vez
permitan la gestión de la información, su tratamiento e intercambio, de manera eficaz
entre los diferentes elementos que componen la arquitectura de servicios de información
de tráfico, como los usuarios, aplicaciones, y proveedores de la información.
Para la consecución de los objetivos marcados han sido desarrollados diversos
elementos como parte integrante de una arquitectura, que supusieron determinados
aportes y/o resultados:
1. Construcción de una infraestructura ontológica cuyo dominio queda enmarcado
en la información sobre tráfico vial.
2. Se ha expuesto un marco de trabajo para la conversión de portales Web
convencionales de información en Servicios Web Semánticos (SWS).
3. Extensión a las metodologías de construcción de ontologías, previamente
existentes, para plantear el proceso a seguir en la obtención de un modelo
semántico formal a partir de un modelo de Entidad-Relación (ER).
4. Se ha diseñado, implementado y evaluado, un algoritmo de emparejamiento de
SWS, que aprovecha al máximo las capacidades proporcionadas por las
ontologías de descripción de servicios y que constituye una mejora de los ya
existentes. Inclusión del grado fraternal o de hermanos y otra serie de
modificaciones.
5. Se han mostrado una serie de propuestas que permiten crear y manejar Servicios
Web Semánticos de información de tráfico vial: nuevo parámetro no funcional
(valor añadido), ontología de categorización de servicios de tráfico y elección de
factores de medida en la QoS.
Finalmente las propuestas han sido validadas a partir del desarrollo de un prototipo
software basado en la arquitectura de integración de SWS de información sobre tráfico
vial, que ha permitido el ensamblaje de todos los elementos (ontologías de tráfico,
algoritmo de emparejamiento, servicios de información de tráfico), obtenidos como
resultado en cada una de las etapas de esta investigación.
__________________________________________________________________________________________________This thesis forms part of the common Intelligent Transportation Systems which in turn
are based on the application of telecommunication and Informatics (Telematics) to
traffic management which belongs to the domain of Traveller Information..
The principle identified problems are the lack of a common vocabulary of elements
which use a well defined semantic description which permits obtaining the meaning
(including the non-explicit) of each concept of rural traffic as well as obtaining
information from different heterogeneous sources in an intuitive and simple way.
Different aspects describe the actual problem related to the access and distribution of
information:
1. High volume of traffic information is distributed over different web sites. The
main problem for a user who needs such information is to find such webs and
handle the different ways of access and presentation
2. On the other hand, the users need information of a different nature or type, and
the storage of such information on a simple site would be too costly as well for
maintenance.
3. It is no possible to obtain any information if this information is not explicit
before,
After defining the existing problems and identifying the elements which could solve this
situation, the present work focuses on those ITS-systems which provide traffic
information to the user, its handling and exchange, in an efficient way between the
elements which compose the architecture of traffic information systems, such as users
applications and information providers.
Different elements have been developed as an integral part of an architecture:
1. Construction of an ontological infrastructure which domain is covered by road
traffic information,
2. A framework was defined for the conversion of conventional web portals to
semantic web services (SWS),
3. Extension of the existing methodology for the construction of ontologies based
on ER model,
4. A SWS matching algorithm was designed, implemented and evaluated which
make maximal use of the capabilities of the ontologies of the service description,
which constitute an improvement of the existing ones.
5. A number of proposals were demonstrated which permits creation and handling
of Semantic web services of road traffic information
Semantic search and composition in unstructured peer-to-peer networks
This dissertation focuses on several research questions in the area of semantic search and composition in unstructured peer-to-peer (P2P) networks. Going beyond the state of the art, the proposed semantic-based search strategy S2P2P offers a novel path-suggestion based query routing mechanism, providing a reasonable tradeoff between search performance and network traffic overhead. In addition, the first semantic-based data replication scheme DSDR is proposed. It enables peers to use semantic information to select replica numbers and target peers to address predicted future demands. With DSDR, k-random search can achieve better precision and recall than it can with a near-optimal non-semantic replication strategy. Further, this thesis introduces a functional automatic semantic service composition method, SPSC. Distinctively, it enables peers to jointly compose complex workflows with high cumulative recall but low network traffic overhead, using heuristic-based bidirectional haining and service memorization mechanisms. Its query branching method helps to handle dead-ends in a pruned search space. SPSC is proved to be sound and a lower bound of is completeness is given. Finally, this thesis presents iRep3D for semantic-index based 3D scene selection in P2P search. Its efficient retrieval scales to answer hybrid queries involving conceptual, functional and geometric aspects. iRep3D outperforms previous representative efforts in terms of search precision and efficiency.Diese Dissertation bearbeitet Forschungsfragen zur semantischen Suche und Komposition in unstrukturierten Peer-to-Peer Netzen(P2P). Die semantische Suchstrategie S2P2P verwendet eine neuartige Methode zur Anfrageweiterleitung basierend auf Pfadvorschlägen, welche den Stand der Wissenschaft übertrifft. Sie bietet angemessene Balance zwischen Suchleistung und Kommunikationsbelastung im Netzwerk. Außerdem wird das erste semantische System zur Datenreplikation genannt DSDR vorgestellt, welche semantische Informationen berücksichtigt vorhergesagten zukünftigen Bedarf optimal im P2P zu decken. Hierdurch erzielt k-random-Suche bessere Präzision und Ausbeute als mit nahezu optimaler nicht-semantischer Replikation. SPSC, ein automatisches Verfahren zur funktional korrekten Komposition semantischer Dienste, ermöglicht es Peers, gemeinsam komplexe Ablaufpläne zu komponieren. Mechanismen zur heuristischen bidirektionalen Verkettung und Rückstellung von Diensten ermöglichen hohe Ausbeute bei geringer Belastung des Netzes. Eine Methode zur Anfrageverzweigung vermeidet das Feststecken in Sackgassen im beschnittenen Suchraum. Beweise zur Korrektheit und unteren Schranke der Vollständigkeit von SPSC sind gegeben. iRep3D ist ein neuer semantischer Selektionsmechanismus für 3D-Modelle in P2P. iRep3D beantwortet effizient hybride Anfragen unter Berücksichtigung konzeptioneller, funktionaler und geometrischer Aspekte. Der Ansatz übertrifft vorherige Arbeiten bezüglich Präzision und Effizienz