Repositories

@automerge/automerge provides a JSON-like CRDT and a sync protocol, but this still leaves a lot of plumbing to do to use it in an application. @automerge/automerge-repo is that plumbing.

The entry point for an automerge-repo based application is to create a Repo, passing it some form of StorageAdapter - which knows how to save data locally - and zero or more NetworkAdapters, which know how to talk to other peers running automerge-repo.

For example, this snippet creates a Repo which listens for websocket connections and stores data in the local file system:

import { Repo } from "@automerge/automerge-repo";
import { WebSocketServer } from "ws";
import { NodeWSServerAdapter } from "@automerge/automerge-repo-network-websocket";
import { NodeFSStorageAdapter } from "@automerge/automerge-repo-storage-nodefs";

const wss = new WebSocketServer({ noServer: true });

const repo = new Repo({
  network: [new NodeWSServerAdapter(wss)],
  storage: new NodeFSStorageAdapter(dir),
});

A Repo is a little like a database. It allows you to create and request DocHandles. Once you have a DocHandle you can make changes to it and listen for changes received from other peers.

let doc = repo.create();
// Make a change ourselves and send that to everyone else
doc.change((d) => (d.text = "hello world"));
// Listen for changes from other peers
doc.on("change", ({ doc }) => {
  console.log("new text is ", doc.text);
});

Any changes you make - or which are received from the network - will be stored in the attached storage adapter and distributed to other peers