@kele23/level-sync

LEVEL SYNC

!Repository under development!

Sync multiple LevelDB instances. It works on both browser and nodejs!!!

Usage

// create level-logged
const db = new LevelLogged(new Level()<string, any>('./db'));

// create a connection
const p2p = new Peer();
const connection = new P2PConnection(p2p);
p2p.on('connection', (dataConnection) => {
    connection.incomingConnection(dataConnection);
});

// connect connection & db with the sync manager
const sync = new SyncManager(db, connection);

// various sync
sync.doPull(); // pull from other db to mine
sync.doPush(); // push from my db to other
sync.doSync(); // pull and then push
sync.doSync(interval); // make a sync every <interval> seconds
sync.isScheduled(); // true if there is a sync scheduled
sync.stopSync();

Types of connections

P2P Connection based on PeerJS

const p2p = new Peer(); // PeerJS
const connection = new P2PConnection(p2p);
p2p.on('connection', (dataConnection) => {
    connection.incomingConnection(dataConnection);
});

Generic CLIENT-SERVER

Client

const connection = new ClientConnection(async (data) => {
    return await axios.put(...
});

Server

const connection = new ServerConnection();
server.onReceive(async (data) => {
    return await connection.incomingReceive(data);
});

Conflicts

When a Master - Master replication occurs it is always possible for conflicts to occur.

Conflicts can arise in various situations, the most common is that both DBs have modified the same key and therefore it is necessary to understand which of the two versions to keep. For the moment, conflicts are resolved by maintaining the "remote" version, in order to be as simple as possible.

As soon as possible we will also try to implement a custom management.

Next Steps

• Verify AbstractLevel implementation & Create test suite ( found the correct test framework )
• Versioning ( mantain old versions of elements if is possible )
• Log cleaning ( purge too old logs )
• Reduce communication overhead
• Batch communication & batch commit