2,599 research outputs found

    A schema-based P2P network to enable publish-subscribe for multimedia content in open hypermedia systems

    No full text
    Open Hypermedia Systems (OHS) aim to provide efficient dissemination, adaptation and integration of hyperlinked multimedia resources. Content available in Peer-to-Peer (P2P) networks could add significant value to OHS provided that challenges for efficient discovery and prompt delivery of rich and up-to-date content are successfully addressed. This paper proposes an architecture that enables the operation of OHS over a P2P overlay network of OHS servers based on semantic annotation of (a) peer OHS servers and of (b) multimedia resources that can be obtained through the link services of the OHS. The architecture provides efficient resource discovery. Semantic query-based subscriptions over this P2P network can enable access to up-to-date content, while caching at certain peers enables prompt delivery of multimedia content. Advanced query resolution techniques are employed to match different parts of subscription queries (subqueries). These subscriptions can be shared among different interested peers, thus increasing the efficiency of multimedia content dissemination

    Proof-of-Concept Application - Annual Report Year 1

    Get PDF
    In this document the Cat-COVITE Application for use in the CATNETS Project is introduced and motivated. Furthermore an introduction to the catallactic middleware and Web Services Agreement (WS-Agreement) concepts is given as a basis for the future work. Requirements for the application of Cat-COVITE with in catallactic systems are analysed. Finally the integration of the Cat-COVITE application and the catallactic middleware is described. --Grid Computing

    Data storage solutions for the federation of sensor networks

    Get PDF
    In the near future, most of our everyday devices will be accessible via some network and uniquely identified for interconnection over the Internet. This new paradigm, called Internet of Things (IoT), is already starting to influence our society and is now driving developments in many areas. There will be thousands, or even millions, of constrained devices that will be connected using standard protocols, such as Constrained Application Protocol (CoAP), that have been developed under certain specifications appropriate for this type of devices. In addition, there will be a need to interconnect networks of constrained devices in a reliable and scalable way, and federations of sensor networks using the Internet as a medium will be formed. To make the federation of geographically distributed CoAP based sensor networks possible, a CoAP Usage for REsource LOcation And Discovery (RELOAD) was recently proposed. RELOAD is a peer-to-peer (P2P) protocol that ensures an abstract storage and messaging service to its clients, and it relies on a set of cooperating peers that form a P2P overlay network for this purpose. This protocol allows to define so-called Usages for applications to work on top of this overlay network. The CoAP Usage for RELOAD is, therefore, a way for CoAP based devices to store their resources in a distributed P2P overlay. Although CoAP Usage for RELOAD is an important step towards the federation of sensor networks, in the particular case of IoT there will be consistency and efficiency problems. This happens because the resources of CoAP devices/Things can be in multiple data objects stored at the overlay network, called P2P resources. Thus, Thing resource updates can end up being consuming, as multiple P2P resources will have to be modified. Mechanisms to ensure consistency become, therefore, necessary. This thesis contributes to advances in the federation of sensor networks by proposing mechanisms for RELOAD/CoAP architectures that will allow consistency to be ensured. An overlay network service, required for such mechanisms to operate, is also proposed.Num futuro prĂłximo, a maioria dos nossos dispositivos do dia-a-dia estarĂŁo acessĂ­veis atravĂ©s de uma rede e serĂŁo identificados de forma Ășnica para poderem interligar-se atravĂ©s da Internet. Este novo paradigma, conhecido hoje por Internet das Coisas (IoT), jĂĄ estĂĄ a começar a influenciar a nossa sociedade e estĂĄ agora a impulsionar desenvolvimentos em inĂșmeras ĂĄreas. Teremos milhares, ou mesmo milhĂ”es, de dispositivos restritos que utilizarĂŁo protocolos padrĂŁo que foram desenvolvidos de forma a cumprir determinadas especificaçÔes associadas a este tipo de dispositivos, especificaçÔes essas que tĂȘm a ver com o facto destes dispositivos terem normalmente restriçÔes de memĂłria, pouca capacidade de processamento e muitos possuirem limitaçÔes energĂ©ticas. SurgirĂĄ ainda a necessidade de interligar, de forma fiĂĄvel e escalonĂĄvel, redes de dispositivos restritos.(


    An Overlay Architecture for Personalized Object Access and Sharing in a Peer-to-Peer Environment

    Get PDF
    Due to its exponential growth and decentralized nature, the Internet has evolved into a chaotic repository, making it difficult for users to discover and access resources of interest to them. As a result, users have to deal with the problem of information overload. The Semantic Web's emergence provides Internet users with the ability to associate explicit, self-described semantics with resources. This ability will facilitate in turn the development of ontology-based resource discovery tools to help users retrieve information in an efficient manner. However, it is widely believed that the Semantic Web of the future will be a complex web of smaller ontologies, mostly created by various groups of web users who share a similar interest, referred to as a Community of Interest. This thesis proposes a solution to the information overload problem using a user driven framework, referred to as a Personalized Web, that allows individual users to organize themselves into Communities of Interests based on ontologies agreed upon by all community members. Within this framework, users can define and augment their personalized views of the Internet by associating specific properties and attributes to resources and defining constraint-functions and rules that govern the interpretation of the semantics associated with the resources. Such views can then be used to capture the user's interests and integrate these views into a user-defined Personalized Web. As a proof of concept, a Personalized Web architecture that employs ontology-based semantics and a structured Peer-to-Peer overlay network to provide a foundation of semantically-based resource indexing and advertising is developed. In order to investigate mechanisms that support the resource advertising and retrieval of the Personalized Web architecture, three agent-driven advertising and retrieval schemes, the Aggressive scheme, the Crawler-based scheme, and the Minimum-Cover-Rule scheme, were implemented and evaluated in both stable and churn environments. In addition to the development of a Personalized Web architecture that deals with typical web resources, this thesis used a case study to explore the potential of the Personalized Web architecture to support future web service workflow applications. The results of this investigation demonstrated that the architecture can support the automation of service discovery, negotiation, and invocation, allowing service consumers to actualize a personalized web service workflow. Further investigation will be required to improve the performance of the automation and allow it to be performed in a secure and robust manner. In order to support the next generation Internet, further exploration will be needed for the development of a Personalized Web that includes ubiquitous and pervasive resources

    Cross-Layer Peer-to-Peer Track Identification and Optimization Based on Active Networking

    Get PDF
    P2P applications appear to emerge as ultimate killer applications due to their ability to construct highly dynamic overlay topologies with rapidly-varying and unpredictable traffic dynamics, which can constitute a serious challenge even for significantly over-provisioned IP networks. As a result, ISPs are facing new, severe network management problems that are not guaranteed to be addressed by statically deployed network engineering mechanisms. As a first step to a more complete solution to these problems, this paper proposes a P2P measurement, identification and optimisation architecture, designed to cope with the dynamicity and unpredictability of existing, well-known and future, unknown P2P systems. The purpose of this architecture is to provide to the ISPs an effective and scalable approach to control and optimise the traffic produced by P2P applications in their networks. This can be achieved through a combination of different application and network-level programmable techniques, leading to a crosslayer identification and optimisation process. These techniques can be applied using Active Networking platforms, which are able to quickly and easily deploy architectural components on demand. This flexibility of the optimisation architecture is essential to address the rapid development of new P2P protocols and the variation of known protocols
    • 

    corecore