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Thespis is a middleware that innovatively leverages the Actor model to implement causal consistency over an industry-standard database, whilst abstracting complexities for application developers behind a REST open-protocol interface. Our evaluation considers correctness, performance and scalability aspects. We also run empirical experiments using YCSB to show the efficacy of the approach for a variety...
The Memcached system has no redundancy mechanism. In special cases, there will be a performance degradation of the server and the single-point-of-failure. For these reasons, MS_Memcached, a distributed cache system with master-slave mode, is presented in this paper. It maintains the slaves from the masters with the asynchronous message queue. By using a dynamic feedback load balancing algorithm, the...
Distributed file systems enable the reliable storage of exabytes of information on thousands of servers distributed throughout a network. These systems achieve reliability and performance by storing multiple copies of data blocks in different locations across the network. The management of these copies of data is commonly handled by intermediate servers that track and coordinate the placement of data...
Situational understanding (SU) requires a combination of insight — the ability to accurately perceive an existing situation — and foresight — the ability to anticipate how an existing situation may develop in the future. SU involves information fusion as well as model representation and inference. Commonly, heterogenous data sources must be exploited in the fusion process: often including both hard...
Emerging augmented reality IoT edge devices, such as smart glasses, show significant promise in use as assistive devices that involve human(s) in the loop. Owing to the often safety-critical nature of the assistive application, such as guiding a blind person, both the performance and dependability of the end-to-end system is critical. Among the many technical hurdles in realizing such applications,...
This paper presents a multi-layer secure IoT network model based on blockchain technology. The model reduces the difficulty of actual deployment of the blockchain technology by dividing the Internet of Things into a multi-level de-centric network and adopting the technology of block chain technology at all levels of the network, with the high security and credibility assurance of the blockchain technology...
Current big data cloud systems often use different data migration strategies from providers to customers. This often results in increased bandwidth usage and herewith a decrease of the performance. To enhance the performance often caching mechanisms are adopted. However, the implementations of these caching mechanisms are often dedicated solutions for specific applications and/or use case scenarios...
With the continuing penetration of sensor devices and the development of wireless communication techniques, increasing number of applications involving context awareness in ubiquitous computing have been used in daily life. How to collect data from mobile devices at a low energy cost and to mine contextual habits of users remains a key challenge for ubiquitous computing. We proposed an efficient context-...
The ubiquity of Big Data has greatly influenced the direction and the development of storage technologies. To meet the needs of storing and analyzing Big Data, researchers and administrators have turned to parallel and distributed storage and compute architectures. While the problems of securely and consistently storing and accessing data in large parallel and distributed file systems have been largely...
A promising area that has recently emerged, is on how to use index coding to improve the communication efficiency in distributed computing systems, especially for data shuffling in iterative computations. In this paper, we posit that pliable index coding can offer a more efficient framework for data shuffling, as it can better leverage the many possible shuffling choices to reduce the number of transmissions...
Batch codes, first introduced by Ishai, Kushilevitz, Ostrovsky, and Sahai, mimic a distributed storage of a set of n data items on m servers, in such a way that any batch of k data items can be retrieved by reading at most some t symbols from each server. Combinatorial batch codes, are replication-based batch codes in which each server stores a subset of the data items. In this paper, we propose a...
In modern data centers, many flow-based and task-based schemes have been proposed to speed up the data transmission in order to provide fast, reliable services for millions of users. However, existing flow-based schemes treat all flows in isolation, contributing less to or even hurting user experience due to the stalled flows. Other prevalent task-based approaches, such as centralized and decentralized...
Distributed key-value store-based caching solutions are being increasingly used to accelerate Big Data applications on modern HPC clusters. This has necessitated incorporating fault-tolerance capabilities into high-performance key-value stores such as Memcached that are otherwise volatile in nature. In-memory replication is being used as the primary mechanism to ensure resilient data operations. However,...
This paper explores methodologies, advantages and challenges related to the use of the Information Centric Network technology for developing NoSQL distributed databases, which are expected to play a central role in the forthcoming IoT and BigData era. ICN services make possible to simplify the development of the database software, improve performance, and provide data-level access control. We use...
Network load-balancers generally either do not take application state into account, or do so at the cost of a centralized monitoring system. This paper introduces a load-balancer running exclusively within the IP forwarding plane, i.e. in an application protocol agnostic fashion - yet which still provides application-awareness and makes real-time, decentralized decisions. To that end, IPv6 Segment...
In this work we focus on integrity and consistency of data accessed and manipulated by multiple collaborating users, and stored in an (untrusted) hosted service. This is a problem, aspects of which have been studied in isolation in hitherto distinctcommunities. Consistency is one of the cardinal problems of distributed computing. Integrity of hosted data has been studied over the last decade, and...
With the increasing popularity of serving and storing data in multiple data centers, we investigate the efficiency of majority quorum-based data consistency algorithms under this scenario. Because of the failure-prone nature of distributed storage systems, majority quorum-based data consistency algorithms become one of the most widely adopted approaches. In this paper, we propose the MeteorShower...
Deployed in various distributed storage systems, erasure coding has demonstrated its advantages of low storage overhead and high failure tolerance. Typically in an erasure-coded distributed storage system, systematic maximum distance seperable (MDS) codes are chosen since the optimal storage overhead can be achieved and meanwhile data can be read directly without decoding operations. However, data...
This paper describes a demo of OpenGeoBase, a NoSQL spatio-temporal distributed database that exploits Information Centric Network technology. We show its basic operations and two applications based on it. The first one is an Intelligent Transport System application making possible to discover public transport information (GTFS files) all over the world. The second application concerns a citizen reporting...
A scalable storage system becomes more important today for online social networks (OSNs) as the volume of user data increases rapidly. Key-value store uses consistent hashing to save data in a distributed manner. As a defacto standard, it has been widely used in production environments of many OSNs. However, the random nature of hashing always leads to high inter-server traffic. Recently, partitioning...
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