Eventually-consistent, conflict-free replicated data types (CRDT) implemented using IPFS and LevelDB.

This module and the IPFS PubSub system are experimental. If you encounter an issue, fork the repository, write tests demonstrating the issue, and create a pull request.

const os = require('os');
const path = require('path');
const uuid = require('uuid');
const level = require('level');
const ipfsAPI = require('ipfs-http-client');
const { IpfsObservedRemoveMap } = require('ipfs-observed-remove-level');

const run = async () => {

  const location = path.join(os.tmpdir(), uuid.v4());
  const db = level(location, { valueEncoding: 'json' });
  // IPFS nodes with PubSub enabled
  const ipfs1 = ipfsAPI('/ip4/127.0.0.1/tcp/5001'); 
  const ipfs2 = ipfsAPI('/ip4/127.0.0.1/tcp/5002');

  const topic = "CRDT_MAP";

  const alice = new IpfsObservedRemoveMap(db, ipfs1, topic, [], { namespace:'alice' });
  const bob = new IpfsObservedRemoveMap(db, ipfs2, topic, [], { namespace:'bob' });

  alice.on('set', (key, value) => {
    console.log(key, value); // logs [a, 1], [b, 2]
  });

  await alice.set('a', 1);
  await bob.set('b', 2);

  // Later

  await alice.get('b'); // 2
  await bob.get('a'); // 1
}

yarn add ipfs-observed-remove-level

• constructor
  • Parameters
• ipfsSync
• getIpfsHash
• getIpfsHashes
• ipfsPeerCount
• shutdown
• IpfsObservedRemoveSet#readyPromise

Create an observed-remove CRDT.

• db Object

• ipfs Object? Object implementing the core IPFS API, most likely a js-ipfs or ipfs-http-client object.

• topic String? IPFS pubub topic to use in synchronizing the CRDT.

• entries Iterable<V> Iterable of initial values (optional, default [])

• options Object (optional, default {})

  • options.maxAge String Max age of insertion/deletion identifiers (optional, default 5000)
  • options.bufferPublishing String Interval by which to buffer 'publish' events (optional, default 20)
  • options.chunkPubSub boolean Chunk pubsub messages for values greater than 1 MB (optional, default false)

Publish an IPFS hash of an array containing all of the object's insertions and deletions.

Returns Array<Array<any>>

Stores and returns an IPFS hash of the current insertions and deletions

Returns Promise<string>

Stores and returns an IPFS hash of the current insertions and deletions

Returns Promise<string>

Current number of IPFS pubsub peers.

Returns number

Gracefully shutdown

Returns void

Resolves when IPFS topic subscriptions are confirmed.

Type: Promise<void>

• constructor
  • Parameters
• ipfsSync
• getIpfsHash
• ipfsPeerCount
• shutdown
• IpfsObservedRemoveSet#readyPromise

Create an observed-remove CRDT.

• db Object

• ipfs Object? Object implementing the core IPFS API, most likely a js-ipfs or ipfs-http-client object.

• topic String? IPFS pubub topic to use in synchronizing the CRDT.

• entries Iterable<V> Iterable of initial values (optional, default [])

• options Object (optional, default {})

  • options.maxAge String Max age of insertion/deletion identifiers (optional, default 5000)
  • options.bufferPublishing String Interval by which to buffer 'publish' events (optional, default 20)
  • options.chunkPubSub boolean Chunk pubsub messages for values greater than 1 MB (optional, default false)

Publish an IPFS hash of an array containing all of the object's insertions and deletions.

Returns Array<Array<any>>

Stores and returns an IPFS hash of the current insertions and deletions

Returns Promise<string>

Current number of IPFS pubsub peers.

Returns number

Gracefully shutdown

Returns void

Resolves when IPFS topic subscriptions are confirmed.

Type: Promise<void>