KeepSync

A reactive sync engine framework for use with Tonk apps.

Installation

npm install @tonk/keepsync
# or
yarn add @tonk/keepsync
# or
pnpm add @tonk/keepsync

Features

• Real-time synchronization using CRDTs (Conflict-free Replicated Data Types)
• Built on Automerge for robust conflict resolution
• Seamless integration with React and Zustand
• Automatic reconnection and offline support
• Simple WebSocket-based synchronization
• Persistent storage for offline-first applications
• File system synchronization for collaborative file management

Basic Usage

1. Set Up the Sync Provider

Initialize the sync engine in your application entry point (or before using any synced stores):

// index.tsx
import { initializeSyncEngine } from '@tonk/keepsync';

// Initialize the sync engine
initializeSyncEngine({
  url: 'ws://localhost:4080',
  name: 'MySyncEngine',
  onSync: docId => console.log(`Document ${docId} synced`),
  onError: error => console.error('Sync error:', error),
});

2. Create a Synced Store with the Middleware

Use the sync middleware to create stores that automatically synchronize with other clients:

// stores/counterStore.ts
import { create } from 'zustand';
import { sync } from '@tonk/keepsync';

interface CounterState {
  count: number;
  increment: () => void;
  decrement: () => void;
  reset: () => void;
}

export const useCounterStore = create<CounterState>(
  sync(
    // The store implementation
    set => ({
      count: 0,

      // Increment the counter
      increment: () => {
        set(state => ({ count: state.count + 1 }));
      },

      // Decrement the counter
      decrement: () => {
        set(state => ({ count: Math.max(0, state.count - 1) }));
      },

      // Reset the counter
      reset: () => {
        set({ count: 0 });
      },
    }),
    // Sync configuration
    {
      docId: 'counter',
      // Optional: configure initialization timeout
      initTimeout: 30000,
      // Optional: handle initialization errors
      onInitError: error => console.error('Sync initialization error:', error),
    }
  )
);

3. Use the Store in React Components

// components/Counter.tsx
import React from 'react';
import { useCounterStore } from '../stores/counterStore';

export function Counter() {
  // Use the store hook directly - sync is handled by the middleware
  const { count, increment, decrement, reset } = useCounterStore();

  return (
    <div>
      <h2>Collaborative Counter: {count}</h2>
      <div>
        <button onClick={decrement}>-</button>
        <button onClick={increment}>+</button>
        <button onClick={reset}>Reset</button>
      </div>
      <p>
        <small>
          Open this app in multiple windows to see real-time collaboration in action.
        </small>
      </p>
    </div>
  );
}

4. Access the Sync Engine Directly

If you need to access the sync engine directly:

import { getSyncInstance } from '@tonk/keepsync';

function syncDocument() {
  const syncEngine = getSyncInstance();

  if (syncEngine) {
    // Manually update a document
    syncEngine.updateDocument('my-document', doc => {
      doc.someProperty = 'new value';
    });

    // Get a document
    syncEngine.getDocument('my-document').then(doc => {
      console.log('Document content:', doc);
    });
  } else {
    console.warn('Sync engine not initialized yet');
  }
}

5. Synced File System

KeepSync also provides a file system API for collaborative file management:

import {
  configureSyncedFileSystem,
  addFile,
  getAllFiles,
  getFile,
  removeFile,
} from '@tonk/keepsync';

// Configure the synced file system
configureSyncedFileSystem({
  docId: 'my-files',
  dbName: 'my-app-files',
  storeName: 'file-blobs',
});

// Add a file
const fileInput = document.getElementById('fileInput') as HTMLInputElement;
fileInput.addEventListener('change', async () => {
  if (fileInput.files && fileInput.files.length > 0) {
    const file = fileInput.files[0];
    const metadata = await addFile(file);
    console.log('Added file:', metadata);
  }
});

// List all files
async function displayAllFiles() {
  const files = await getAllFiles();
  console.log('All files:', files);

  // Display files in UI
  const fileList = document.getElementById('fileList');
  if (fileList) {
    fileList.innerHTML = '';
    files.forEach(file => {
      const item = document.createElement('div');
      item.textContent = `${file.name} (${file.size} bytes)`;

      // Add download button
      const downloadBtn = document.createElement('button');
      downloadBtn.textContent = 'Download';
      downloadBtn.onclick = async () => {
        const blob = await getFile(file.hash);
        if (blob) {
          const url = URL.createObjectURL(blob);
          const a = document.createElement('a');
          a.href = url;
          a.download = file.name;
          a.click();
          URL.revokeObjectURL(url);
        }
      };

      // Add delete button
      const deleteBtn = document.createElement('button');
      deleteBtn.textContent = 'Delete';
      deleteBtn.onclick = async () => {
        await removeFile(file.hash);
        displayAllFiles(); // Refresh the list
      };

      item.appendChild(downloadBtn);
      item.appendChild(deleteBtn);
      fileList.appendChild(item);
    });
  }
}

Setting Up the Sync Server

KeepSync uses a simple WebSocket server for synchronization:

import { WebSocketServer } from 'ws';
import { createServer } from 'http';

// Create a simple HTTP server
const server = createServer();
const wss = new WebSocketServer({
  server,
  path: '/sync',
});

// Store connected clients
const connections = new Set();

// Handle WebSocket connections
wss.on('connection', ws => {
  console.log('Client connected');
  connections.add(ws);

  // Handle messages from clients
  ws.on('message', data => {
    connections.forEach(client => {
      if (client !== ws && client.readyState === WebSocket.OPEN) {
        client.send(data.toString());
      }
    });
  });

  // Handle client disconnection
  ws.on('close', () => {
    console.log('Client disconnected');
    connections.delete(ws);
  });
});

// Start the server
const PORT = process.env.PORT || 8040;
server.listen(PORT, () => {
  console.log(`Sync server running on port ${PORT}`);
});

Cleanup

When your application is shutting down, make sure to clean up resources:

import { closeSyncEngine, closeSyncedFileSystem } from '@tonk/keepsync';

// Clean up everything when the app is shutting down
function shutdownApp() {
  closeSyncedFileSystem();
  closeSyncEngine();
}

License

MIT