Ad-UDDI: An Active and Distributed Service Registry

Abstract. In SOA (Service Oriented Architecture), web service providers use service registries to publish services and requestors use registries to find them. The major current service registry specifications, UDDI (Universal Description, Discovery and Integration), has the following drawbacks. First, it replicates all public service publications in all UBR (Universal Business Registry) nodes, which is not scalable and efficient, and second, it collects service information in a passive manner, which means it waits for service publication, updating or discovery request passively and thus cannot guarantee the real-time validity of the services information. In this paper, we propose an active and distributed UDDI architecture called Ad-UDDI, which extends and organizes the private or semi-private UDDIs based on industry classifications. Further, Ad-UDDI adopts an active monitoring mechanism, so that service information can be updated automatically and the service requestors may find the latest service information conveniently. We evaluate Ad-UDDI by comprehensive simulations and experimental results show that it outperforms existing approaches significantly.

CloudVO: building a secure virtual organization for multiple clouds collaboration

Cloud computing has become a popular computing paradigm in which virtualized and scalable resources are consolidated to provide services over Internet. However, the resource capability of a single cloud is generally limited, and some applications often require various cloud centers over Internet to deliver services together. Therefore, a Virtual Organization (VO) will be a promising approach to integrate services and users across multiple autonomous clouds. However, how to build a secure virtual organization to achieve the collaboration goals is a critical problem, and some issues such as membership agreement, policy conflict and trust management should be adequately addressed. In this paper, we present a framework CloudVO which based on security policies and trust management techniques to provide some flexible and dynamic VO management protocols for clouds. Therefore, CloudVO can achieve inter-cloud collaboration without destroying a cloud's local policies. Based on previous VO security management experiences, we have conducted some preliminary simulations to verify the effectiveness our approaches for cloud computing environments

CROWN FlowEngine: A GPEL-Based Grid Workflow Engine

Abstract. Currently some complex grid applications developing often need orchestrate multiple diverse grid services into a workflow of tasks that can submit for executing on the grid environment. In this paper, we present CROWN FlowEngine—a GPEL-based grid workflow engine for executing grid workflow instances. Besides basic functions of a conventional BPEL4WSbased workflow engine, CROWN FlowEngine has many features including hierarchical processing mechanism, multiple types of task scheduling, transaction processing, etc, which are of paramount importance to supporting workflow instances using GPEL language. CROWN FlowEngine will be adopted and widely deployed in CROWN Grid environment to support a wide range of service grid applications integration. We conduct several experiments to evaluate the performance of CROWN FlowEngine, and the results of comparing our work with GWES are presented as well.

Electrical Manipulation of Antiferromagnetic Random‐Access Memory Device by the Interplay of Spin‐Orbit Torque and Spin‐Transfer Torque

Abstract Antiferromagnets (AFM) hold significant promise as ideal candidates for high‐density and ultrafast memory applications. Electrical manipulation of exchange bias (EB) has emerged as an effective solution to integrate AFMs into magnetic memories as active elements. In particular, spin‐orbit torque antiferromagnetic random‐access memory (SOT‐ARAM) is recently been demonstrated by using an AFM/FM hybrid free layer, which can simultaneously satisfy field‐free switching and good device scalability. However, the switching current density of the exchange bias in SOT‐ARAM devices is still high, and novel functionalities are exploited in this device scheme. In this study, the all‐electrical manipulation of the ARAM devices through the interplay of SOT and spin‐transfer torque (STT) is reported, both in three‐terminal and two‐terminal configurations. The SOT current density achieves a 40% reduction thanks to the incorporation of the STT current. Macrospin simulations are performed to illustrate the underlying mechanism. Further, a majority gate that can be decomposed into reconfigurable AND/OR functionalities in a single ARAM device is demonstrated, with an operation speed as fast as 2 ns. The results can advance the development of high‐performance memories and in‐memory computing

Antiferromagnetic spintronics: An overview and outlook

Over the past few decades, the diversified development of antiferromagnetic spintronics has made antiferromagnets (AFMs) interesting and very useful. After tough challenges, the applications of AFMs in electronic devices have transitioned from focusing on the interface coupling features to achieving the manipulation and detection of AFMs. As AFMs are internally magnetic, taking full use of AFMs for information storage has been the main target of research. In this paper, we provide a comprehensive description of AFM spintronics applications from the interface coupling, read-out operations, and writing manipulations perspective. We examine the early use of AFMs in magnetic recordings and conventional magnetoresistive random-access memory (MRAM), and review the latest mechanisms of the manipulation and detection of AFMs. Finally, based on exchange bias (EB) manipulation, a high-performance EB-MRAM is introduced as the next generation of AFM-based memories, which provides an effective method for read-out and writing of AFMs and opens a new era for AFM spintronics