7,370 research outputs found
Investigation into Mobile Learning Framework in Cloud Computing Platform
AbstractâCloud computing infrastructure is increasingly
used for distributed applications. Mobile learning
applications deployed in the cloud are a new research
direction. The applications require specific development
approaches for effective and reliable communication. This
paper proposes an interdisciplinary approach for design and
development of mobile applications in the cloud. The
approach includes front service toolkit and backend service
toolkit. The front service toolkit packages data and sends it
to a backend deployed in a cloud computing platform. The
backend service toolkit manages rules and workflow, and
then transmits required results to the front service toolkit.
To further show feasibility of the approach, the paper
introduces a case study and shows its performance
FastPay: High-Performance Byzantine Fault Tolerant Settlement
FastPay allows a set of distributed authorities, some of which are Byzantine,
to maintain a high-integrity and availability settlement system for pre-funded
payments. It can be used to settle payments in a native unit of value
(crypto-currency), or as a financial side-infrastructure to support retail
payments in fiat currencies. FastPay is based on Byzantine Consistent Broadcast
as its core primitive, foregoing the expenses of full atomic commit channels
(consensus). The resulting system has low-latency for both confirmation and
payment finality. Remarkably, each authority can be sharded across many
machines to allow unbounded horizontal scalability. Our experiments demonstrate
intra-continental confirmation latency of less than 100ms, making FastPay
applicable to point of sale payments. In laboratory environments, we achieve
over 80,000 transactions per second with 20 authorities---surpassing the
requirements of current retail card payment networks, while significantly
increasing their robustness
Trends in Development of Databases and Blockchain
This work is about the mutual influence between two technologies: Databases
and Blockchain. It addresses two questions: 1. How the database technology has
influenced the development of blockchain technology?, and 2. How blockchain
technology has influenced the introduction of new functionalities in some
modern databases? For the first question, we explain how database technology
contributes to blockchain technology by unlocking different features such as
ACID (Atomicity, Consistency, Isolation, and Durability) transactional
consistency, rich queries, real-time analytics, and low latency. We explain how
the CAP (Consistency, Availability, Partition tolerance) theorem known for
databases influenced the DCS (Decentralization, Consistency, Scalability)
theorem for the blockchain systems. By using an analogous relaxation approach
as it was used for the proof of the CAP theorem, we postulate a
"DCS-satisfiability conjecture." For the second question, we review different
databases that are designed specifically for blockchain and provide most of the
blockchain functionality like immutability, privacy, censorship resistance,
along with database features.Comment: Accepted in The Second International Workshop on Blockchain
Applications and Theory (BAT 2020
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Analysis of operating system diversity for intrusion tolerance
One of the key benefits of using intrusion-tolerant systems is the possibility of ensuring correct behavior in the presence of attacks and intrusions. These security gains are directly dependent on the components exhibiting failure diversity. To what extent failure diversity is observed in practical deployment depends on how diverse are the components that constitute the system. In this paper, we present a study with operating system's (OS's) vulnerability data from the NIST National Vulnerability Database (NVD). We have analyzed the vulnerabilities of 11 different OSs over a period of 18âyears, to check how many of these vulnerabilities occur in more than one OS. We found this number to be low for several combinations of OSs. Hence, although there are a few caveats on the use of NVD data to support definitive conclusions, our analysis shows that by selecting appropriate OSs, one can preclude (or reduce substantially) common vulnerabilities from occurring in the replicas of the intrusion-tolerant system
A Survey of Fault-Tolerance and Fault-Recovery Techniques in Parallel Systems
Supercomputing systems today often come in the form of large numbers of
commodity systems linked together into a computing cluster. These systems, like
any distributed system, can have large numbers of independent hardware
components cooperating or collaborating on a computation. Unfortunately, any of
this vast number of components can fail at any time, resulting in potentially
erroneous output. In order to improve the robustness of supercomputing
applications in the presence of failures, many techniques have been developed
to provide resilience to these kinds of system faults. This survey provides an
overview of these various fault-tolerance techniques.Comment: 11 page
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