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This paper presents UbiCon (Ubiquitous Con- sistency), a new model for consistency that enables a node to fetch the latest version of a content object without necessarily fetching from the replica which contains the latest content object version. This differs from eventual consistency type models in which any update issued or received in the distributed system is eventually seen by a node. A client in UbiCon is only interested in the latest version of a content object at fetch time and may not see all previous versions and types of a content object though is able to fetch the latest version and type. UbiCon’s core contribution is a new model for consistency that is 2 dimensional in nature and exploits content based networks, “data is everywhere, made accessible”. Content based networks replace the narrow waistband of the network stack so that content is pulled from the ether rather than specifying a particular host. UbiCon exploits the pervasive existence of data in content networks so that the focus is not on ensuring consistency of the latest versions amongst replicas, rather the availability and multitude of different versions of content across the network is accessed and utilized by UbiCon so that various versions of content objects may be retrieved and computations reused. UbiCon reuses transcoding computations that an individual device may perform and avoids pollution attacks by leveraging the trust inherent in the social overlay formed to share photos amongst friends. UbiCon works as well as traditional consistency models where data is fetched from the replica that contains the matching content version and type. However, when content and its associated diffs can be found at a close by replica that is a couple hops away rather than a replica that may be dozen or more hops away UbiCon attains a throughput and fetch time as if the replica did not have an older version though rather the latest version being fetched.

Paper: PDF file of paper
Slides: PPT file of slides

Information & Date

, , May. 2012


Josh Joy
Saro Meguerdichian