Fisheye consistency: Keeping data in synch in a georeplicated world

Roy Friedman, Michel Raynal, Francois Taïani

Research output: Chapter in Book/Report/Conference proceedingConference contributionpeer-review


Over the last thirty years, numerous consistency conditions for replicated data have been proposed and implemented. Popular examples include linearizability (or atomicity), sequential consistency, causal consistency, and eventual consistency. These conditions are usually defined independently from the computing entities (nodes) that manipulate the replicated data; i.e., they do not take into account how computing entities might be linked to one another, or geographically distributed. To address this lack, as a first contribution, this paper introduces the notion of proximity graph between computing nodes. If two nodes are connected in this graph, their operations must satisfy a strong consistency condition, while the operations invoked by other nodes are allowed to satisfy a weaker condition. The second contribution exploits this graph to provide a generic approach to the hybridization of data consistency conditions within the same system. We illustrate this approach on sequential consistency and causal consistency, and present a model in which all data operations are causally consistent, while operations by neighboring processes in the proximity graph are sequentially consistent. The third contribution of the paper is the design and the proof of a distributed algorithm based on this proximity graph, which combines sequential consistency and causal consistency (the resulting condition is called fisheye consistency). In doing so the paper provides a generic provably correct solution of direct relevance to modern georeplicated systems.

Original languageEnglish
Title of host publicationNetworked Systems - 3rd International Conference, NETYS 2015, Revised Selected Papers
EditorsAhmed Bouajjani, Hugues Fauconnier
Number of pages17
StatePublished - 2015
Event3rd International Conference on Networked Systems, NETYS 2015 - Agadir, Morocco
Duration: 13 May 201515 May 2015

Publication series

NameLecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics)


Conference3rd International Conference on Networked Systems, NETYS 2015


  • Asynchronous message-passing systems
  • Broadcast
  • Causal consistency
  • Data replication
  • Georeplication
  • Linearizability
  • Sequential consistency

All Science Journal Classification (ASJC) codes

  • Theoretical Computer Science
  • Computer Science(all)


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