4,354 research outputs found
Quorums Systems as a Method to Enhance Collaboration for Achieving Fault Tolerance in Distributed System
A system that implements the byzantine agreement algorithm is supposed to be very reliable and robust because of its fault tolerating feature. For very realistic environments, byzantine agreement protocols becomes inadequate, because they are based on the assumption that failures are controlled and they have unlimited severity. The byzantine agreement model works with a number of bounded failures that have to be tolerated. It is never concerned to identify these failures or to exclude them from the system. In this paper, we tackle quorum systems, which is a particular sort of distributed systems where some storage or computations are replicated on various machines in the idea that some of them work correctly to produce a reliable output at some given moment of time. Thus, by majority voting collaboration with quorums, one can achieve fault tolerance in distributed systems. Further, we argue that an algorithm to identify faulty-behaving machines is useful to identify purposeful malicious behaviors
On Secure Workflow Decentralisation on the Internet
Decentralised workflow management systems are a new research area, where most
work to-date has focused on the system's overall architecture. As little
attention has been given to the security aspects in such systems, we follow a
security driven approach, and consider, from the perspective of available
security building blocks, how security can be implemented and what new
opportunities are presented when empowering the decentralised environment with
modern distributed security protocols. Our research is motivated by a more
general question of how to combine the positive enablers that email exchange
enjoys, with the general benefits of workflow systems, and more specifically
with the benefits that can be introduced in a decentralised environment. This
aims to equip email users with a set of tools to manage the semantics of a
message exchange, contents, participants and their roles in the exchange in an
environment that provides inherent assurances of security and privacy. This
work is based on a survey of contemporary distributed security protocols, and
considers how these protocols could be used in implementing a distributed
workflow management system with decentralised control . We review a set of
these protocols, focusing on the required message sequences in reviewing the
protocols, and discuss how these security protocols provide the foundations for
implementing core control-flow, data, and resource patterns in a distributed
workflow environment
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