# Sync

Sync entity data between peers for real-time collaboration using [CRDT](https://en.wikipedia.org/wiki/Conflict-free_replicated_data_type) documents.

This package provides the syncing layer for real-time collaboration in the WordPress editor. It is built on [Yjs](https://docs.yjs.dev/), a CRDT implementation that enables multiple users to edit shared data concurrently without conflicts.

See [CODE.md](./CODE.md) for architecture details.

## Installation

Install the module

```bash
npm install @wordpress/sync --save
```

## API

<!-- START TOKEN(Autogenerated API docs) -->

### Awareness

The Awareness protocol should not be considered a public API. It is a third-party library that will experience breaking changes in the future.

In general, awareness for core entity types is implemented by the `core-data` package and third-party Yjs providers should not provide their own awareness implementation. However, it may be desirable for custom entities to have a custom awareness implementation.

### privateApis

Private @wordpress/sync APIs.

### Y

Yjs should not be considered a public API. It is a third-party library that _will_ experience breaking changes in the future. However, in order to allow third-party plugins to provide their own Yjs providers / sync transport, they must import and consume **our instance** of Yjs due to this bug / feature:

<https://github.com/yjs/yjs/issues/438>

In other words, external code must be able to import Yjs from the `@wordpress/sync` package in their code, e.g.:

```ts
import { Y } from '@wordpress/sync';
```

Additionally, this import must resolve to `wp.sync` via `DependencyExtractionWebpackPlugin`. If you are using an older version of `@wordpress/scripts` that does not treat `@wordpress/sync` as an unbundled package, then you can use Webpack externals to manually resolve the package to the global `wp.sync` variable:

```ts
externals: {
  ...existingConfig.externals,
  // Resolve @wordpress/sync to the global `wp.sync` provided by WordPress.
  '@wordpress/sync': 'wp.sync',

  // Resolve Yjs to the global `wp.sync.Y` provided by the sync package.
  // Since dependencies import 'yjs' directly, we need to avoid importing
  // and packaging two different Yjs instances, which would result in this
  // conflict:
  //
  // https://github.com/yjs/yjs/issues/438
  yjs: 'wp.sync.Y',
},
```

### YJS_VERSION

The major version of Yjs that is bundled and exported by this package. This can be used by third-party code to ensure that they are targeting a compatible version of Yjs.

<!-- END TOKEN(Autogenerated API docs) -->

## Contributing to this package

This is an individual package that's part of the Gutenberg project. The project is organized as a monorepo. It's made up of multiple self-contained software packages, each with a specific purpose. The packages in this monorepo are published to [npm](https://www.npmjs.com/) and used by [WordPress](https://make.wordpress.org/core/) as well as other software projects.

To find out more about contributing to this package or Gutenberg as a whole, please read the project's main [contributor guide](https://github.com/WordPress/gutenberg/tree/HEAD/CONTRIBUTING.md).

<br /><br /><p align="center"><img src="https://s.w.org/style/images/codeispoetry.png?1" alt="Code is Poetry." /></p>