Chord File Sharing is a decentralized and peer-to-peer file-sharing application that utilizes the Chord DHT (Distributed Hash Table) protocol for efficient and scalable file distribution. This version of the project incorporates gRPC (gRPC Remote Procedure Calls) for communication between nodes, enhancing the efficiency and maintainability of the system. This Java application is a Chord Ring Management System that allows users to interact with a Chord distributed hash table (DHT) ring. The system provides various commands for uploading files, joining or creating a ring, printing the finger table, listing stored files and their corresponding keys, downloading files, and displaying node information. For more information, please refer to the Chord Paper. This project also uses GitHub Actions for continuous integration.
- Decentralized File Sharing: Chord File Sharing eliminates the need for a centralized server, allowing users to share files directly with each other.
- Scalability: The Chord DHT protocol enables scalable and efficient file sharing, making it suitable for a large number of users.
- Secure: The decentralized nature of the system enhances security, as there is no single point of failure or vulnerability.
- Persistent Content Hosting: Users can upload their content to the Chord ring, and it is stored on another node. This ensures that the content remains available even if the original owner leaves. Users can choose to host other content when they are online, contributing to the resilience and availability of shared files.
- Stabilization: The Chord ring is self-stabilizing, keeping nodes' successor pointers up to date, and telling the successor about itself, which is sufficient to guarantee the correctness of lookups. If a node leaves the ring, the current successor does not exist. It will not actively find a new successor, fixed fingers will tell the current node the correct successor.
- Fix Fingers: periodically refresh finger table entries.
- Soft Exit: When a node leaves the ring, it will notify its successor to take over the files that the node is hosting. The successor will update its predecessor pointer to the node's predecessor. It will also update all fingers that reference to self.
To run the chord file-sharing application, set two environment variables: HOST and PORT.
PORTis the port number that the node will listen on.HOSTis the host address of the node. The host address can be a domain name or an IP address.
It will automatically create a folder named with the port number to store the files under resources/<port>. When app
starts, it starts grpc-java as a daemon thread by default.
Example of setting environment variables in IntelliJ IDEA:
HOST=127.0.0.1;PORT=8000
The first node starts the ring should call join with no arguments first to create a new ring. The rest of the nodes
should call join with any known node host and port to join the ring.
upload <file_path>: Upload a file to the Chord ring.join: Start a new Chord ring or join an existing one if no ring is found.join <ip> <port>: Join an existing Chord ring. If no IP and port are provided, start a new ring.ftable: Print the finger table.files: Print the files stored in this node's map and their corresponding keys.download <file_name>: Download a file from the Chord ring.info: Print node information.exit: Quit the Chord ring. This is a graceful exit that notifies all nodes whose finger tables should refer to this node when leaving the ring.
- Implement a GUI for the application.
- Support SSL connection for grpc communication.
- Support when a node leaves the ring, the successor of the node will take over the files that the node is hosting.
- Implement a successor list to keep track of r nearest successors. This enables the node to find its correct successor.
- Files should be stored in multiple nodes to avoid a single point of failure.
- Soft exit.
- Hard exit.