Alternator, my senior project, is a distributed, fault-tolerant, gossip-based key-value store for IoT networks. Its key feature is that the user can select the nodes which will store and replicate every individual entry value in the store. This is useful in IoT networks and more generally in heterogeneous networks because it allows the user to map keys to nodes depending on specific features of those nodes. For example, essential data can be stored in nodes with a low disk failure rate and data required for complex operations can be stored in nodes with powerful CPUs.

• The storage scheme is a ring, much like Chord. The coordinator of any key-value pair is the successor of the hash of the key (the pair's name).

• The coordinator of a pair stores its metadata. This includes the ID of the nodes that are in charge of replicating the key's corresponding value. The coordinator does not store the value itself. Metadata is also replicated using a simply chain-replication scheme: the N successors of the coordinator also have a copy of a key's metadata, so the data can be found and puts can still be handled if the coordinator is down.

• Each node keeps a full membership list of the ring, meaning that lookup is constant time, as opposed to Chord's O(logn).

• The membership list is maintained by keeping a history of changes in the ring's membership. These changes are propagated using a simple gossip algorithm.

• Node additions and removals to the ring must be explicit and done by an administrator. I am considering adding automatic failure detection, but that is out of the scope of my project.

This basic scheme allows Alternator to look up any key in constant time, requiring two remote procedure calls for each Get, and N + 1 for each write, where N is the amount of replicating nodes.

Just like with other Go projects, you can find its documentation at the GoDoc site.