124 research outputs found

    DIANA Scheduling Hierarchies for Optimizing Bulk Job Scheduling

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    The use of meta-schedulers for resource management in large-scale distributed systems often leads to a hierarchy of schedulers. In this paper, we discuss why existing meta-scheduling hierarchies are sometimes not sufficient for Grid systems due to their inability to re-organise jobs already scheduled locally. Such a job re-organisation is required to adapt to evolving loads which are common in heavily used Grid infrastructures. We propose a peer-to-peer scheduling model and evaluate it using case studies and mathematical modelling. We detail the DIANA (Data Intensive and Network Aware) scheduling algorithm and its queue management system for coping with the load distribution and for supporting bulk job scheduling. We demonstrate that such a system is beneficial for dynamic, distributed and self-organizing resource management and can assist in optimizing load or job distribution in complex Grid infrastructures.Comment: 8 pages, 9 figures. Presented at the 2nd IEEE Int Conference on eScience & Grid Computing. Amsterdam Netherlands, December 200

    SOA4All, enabling the SOA revolution on a world wide scale

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    SOA4All will help to realize a world where billions of parties are exposing and consuming services via advanced Web technology. The outcome of the project will be a comprehensive framework and infrastructure that integrates four complimentary paradigm-shifting technical advances into a coherent and domain independent service delivery platform: Web principles and technology as the underlying infrastructure for the integration of services at a world wide scale; Web 2.0 as a means to structure human-machine cooperation in an efficient and cost effective manner; Semantic Web technology as a means to abstract from syntax to semantics as required for meaningful service discovery; and context management as a way to process in a machine understandable way user needs that facilitate the customization of existing services for the needs of users

    DIANA Scheduling Hierarchies for Optimizing Bulk Job Scheduling

    Get PDF
    The use of meta-schedulers for resource management in large-scale distributed systems often leads to a hierarchy of schedulers. In this paper, we discuss why existing meta-scheduling hierarchies are sometimes not sufficient for Grid systems due to their inability to re-organise jobs already scheduled locally. Such a job re-organisation is required to adapt to evolving loads which are common in heavily used Grid infrastructures. We propose a peer-topeer scheduling model and evaluate it using case studies and mathematical modelling. We detail the DIANA (Data Intensive and Network Aware) scheduling algorithm and its queue management system for coping with the load distribution and for supporting bulk job scheduling. We demonstrate that such a system is beneficial for dynamic, distributed and self-organizing resource management and can assist in optimizing load or job distribution in complex Grid infrastructures

    A survey of application-level multicast group communication and a proposal for intelligent reflectors

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    The article proposes the state of the art in techniques and models designed to solve issues in application-layer IP multicast. Specifically, the issue of group communication for distributing video flows using reflectors to participants at a videoconference is considered. A proposed solution is introduced, involving an algorithm capable of dynamically discovering the appropriate reflector to meet a given client’s needs. Simulations results show the efficiency of using reflectors in this type of application.5th IFIP International Conference on Network Control & Engineering for QoS, Security and MobilityRed de Universidades con Carreras en Informática (RedUNCI

    NASA Technology Plan 1998

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    This NASA Strategic Plan describes an ambitious, exciting vision for the Agency across all its Strategic Enterprises that addresses a series of fundamental questions of science and research. This vision is so challenging that it literally depends on the success of an aggressive, cutting-edge advanced technology development program. The objective of this plan is to describe the NASA-wide technology program in a manner that provides not only the content of ongoing and planned activities, but also the rationale and justification for these activities in the context of NASA's future needs. The scope of this plan is Agencywide, and it includes technology investments to support all major space and aeronautics program areas, but particular emphasis is placed on longer term strategic technology efforts that will have broad impact across the spectrum of NASA activities and perhaps beyond. Our goal is to broaden the understanding of NASA technology programs and to encourage greater participation from outside the Agency. By relating technology goals to anticipated mission needs, we hope to stimulate additional innovative approaches to technology challenges and promote more cooperative programs with partners outside NASA who share common goals. We also believe that this will increase the transfer of NASA-sponsored technology into nonaerospace applications, resulting in an even greater return on the investment in NASA

    Improve auditing and privacy of electronic health records by using blockchain technology

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    An ever-increasing amount of sensitive patient data is shared between healthcare institutions. The data is strictly personal and the consequences of unintentional disclosure are severe. Recordkeeping systems embedded in the various healthcare systems must therefore adhere to the highest standards of auditability and privacy. Blockchains allow for immutable recordkeeping, which means that data stored on the blockchain cannot be changed or tampered with. Each block on the blockchain stores the computed hash of the contents of the previous block, which makes each new block dependent on the previous block. Nodes store their own copies of the blockchain and keep them synchronized by using mechanisms for distributed consensus. Distributed consensus mechanisms for blockchains facilitate methods to decide which block is to be added to the blockchain next and essentially decide which version of the blockchain is the correct one. This thesis presents an implementation of a blockchain framework for improving auditing and privacy measures of electronic health record (EHR) systems. The framework was partly presented by Yang et. al in 2018 and submitted for publishing in 2019. The proposed framework presents a new layer that can be implemented on top of existing EHR systems. This makes the process of adopting the system much simpler and less costly. The aim of this thesis is to assess how such an implementation can be created using the Hyperledger Fabric blockchain. The implementation facilitates improved privacy and auditing through a solution of storing access control lists and logs directly on the blockchain. Each attempt to access a record is verified in the access control list and subsequently logged before access is granted to the user. This introduces a standard way of managing access control and auditing across several providers, even if the internal system architecture is different for each provider. The layer can be deployed on top of existing systems and only minor changes to the database interfaces are required for the systems to support the new layer. Although the presented implementation is intended for use in EHR systems, it should also be applicable to other types of recordkeeping systems.Masteroppgave i informatikkINF399MAMN-INFMAMN-PRO

    Reliable many-to-many routing in wireless sensor networks using ant colony optimisation

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    A wireless Sensor Network (WSN) consists of many simple sensor nodes gathering information, such as air temperature or pollution. Nodes have limited energy resources and computational power. Generally, a WSN consists of source nodes that sense data and sink nodes that require data to be delivered to them; nodes communicate wirelessly to deliver data between them. Reliability is a concern as, due to energy constraints and adverse environments, it is expected that nodes will become faulty. Thus, it is essential to create fault-tolerant routing protocols that can recover from faults and deliver sensed data efficiently. Often studied are networks with a single sink. However, as applications become increasingly sophisticated, WSNs with multiple sources and multiple sinks become increasingly prevalent but the problem is much less studied. Unfortunately, current solutions for such networks are heuristics based on specific network properties, such as number of sources and sinks. It is beneficial to develop efficient (fault-tolerant) routing protocols, independent of network architecture. As such, the use of meta heuristics are advocated. Presented is a solution for efficient many-to-many routing using the meta heuristic Ant Colony Optimisation (ACO). The contributions are: (i) a distributed ACObased many-many routing protocol, (ii) using the novel concept of beacon ants, a fault-tolerant ACO-based routing protocol for many-many WSNs and (iii) demonstrations of how the same framework can be used to generate a routing protocol based on minimum Steiner tree. Results show that, generally, few message packets are sent, so nodes deplete energy slower, leading to longer network lifetimes. The protocol is scalable, becoming more efficient with increasing nodes as routes are proportionally shorter compared to network size. The fault-tolerant variant is shown to recover from failures while remaining efficient, and successful at continuously delivering data. The ACO-based framework is used to create Steiner Trees in WSNs, an NP-hard problem with many potential applications. The ACO concept provides the basis for a framework that enables the generation of efficient routing protocols that can solve numerous problems without changing the ACO concept. Results show the protocols are scalable, efficient, and can successfully deliver data in numerous different topologies

    A survey of application-level multicast group communication and a proposal for intelligent reflectors

    Get PDF
    The article proposes the state of the art in techniques and models designed to solve issues in application-layer IP multicast. Specifically, the issue of group communication for distributing video flows using reflectors to participants at a videoconference is considered. A proposed solution is introduced, involving an algorithm capable of dynamically discovering the appropriate reflector to meet a given client’s needs. Simulations results show the efficiency of using reflectors in this type of application.5th IFIP International Conference on Network Control & Engineering for QoS, Security and MobilityRed de Universidades con Carreras en Informática (RedUNCI
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