Data Location Management Protocol for Object Stores in a Fog Computing Infrastructure

Fog computing infrastructures have been proposed as an alternative to cloud computing to provide low latency computing for the Internet of Things (IoT). But no storage solutions have been proposed to work specifically in this environment. Existing solutions, relying on a distributed Hash Table to locate the data, are not efficient because location record may be placed far away from the object replicas. In this paper, we propose to use a tree-based approach to locate the data, inspired by the domain name system (DNS) protocol. In our protocol, servers look for the location of an object by requesting successively their ancestors in a tree built with a modified version of the Dijkstra's algorithm applied to the physical topology. Location records are replicated close to the object replicas to limit the network traffic when requesting an object. We evaluate our approach on the Grid'5000 testbed using micro experiments with simple network topologies and a macro experiment using the topology of the French National Research and Education Network (RENATER). In this macro benchmark, we show that the time to locate an object in our approach is less than 15 ms on average which is around 20% shorter than using a traditional distributed Hash Table (DHT).