Victor Ekimov

This is a distributed hash table (DHT) with data partitioning and concurrent replication inspired by Amazon Dynamo. The application is built on top of Java RMI, which is an object-oriented equivalent of remote procedure calls (RPC). Server nodes form a ring topology with items and nodes put in ascending order. Each node is responsible for items falling into the space between current node inclusively and predecessor node exclusively. Client can get or update item from any node in the ring, even if coordinator node does not have item itself.

The Cargo company operates by moving cargo between stations. The cargo represents a movable entity. The station represents permanent storage where cargo remains for some time until transferred to another station. The transfer only happens between two different stations. The stations and transitions form a directed graph with no self-loops, no parallel edges, and is referred to as a cargo map. The cargo map consists of four stations and six transitions. The stations are the Nordic capitals: Helsinki (H), Stockholm (S), Oslo (O) and Copenhagen (C). The transitions are unidirectional (->) paths from station to station: H -> O, H -> S, S -> O, O -> C, C -> S, C -> H. The Cargo map is outlined in the picture below. The orange circles with name tags represent the stations. The orange arrows represent the directed connection between the stations. The green rectangles represent the cargo.