Simple Distributed Hash Table

Developed a Simple Distributed Hash Table based on Chord protocol with below features:

• ID space partitioning/re-partitioning
• ring-based routing
• node joins

Chord DHT is a distributed hash table using consistent hashing which organizes the nodes in a ring.

1. PA Specification: https://docs.google.com/document/d/1Y24TKLiBYLHk7hKFgHy2zQJI3UTHkBbNJ7mGYkwyy6E/edit

2. Testing scripts and instructions are provided in the specification document.

Algorithm implementing Chord: A Scalable Peer-to-peer Lookup Service for Internet Applications

1. Represent the hash Key space as a virtual ring.
2. Use the SHA-1 hash function that evenly distributes items over hash space.
3. Maps the nodes(5 in this project) to buckets in the same ring, i.e a node is responsible for all the hash keys after the previous node's hash.
4. A data item is hashed and stored on the node responsible for the hash (which the succesor node).
5. Each node maintains the successor nodes and any query request is routed from one node to other node in a ring. (Finger tables are not in scope)
6. A node can join the system by requesting the first node of the system which hashes the node to ID space and broadcasts the message to other nodes. (Concurrent node joins are not in scope)
7. The predecessor of the new node and new node updates the pointer succesor node and all the keys belonging to the new node are transferred by the new node successor.
8. Node failures are not in scope.