# Changelog

| Version                      | Release date   |
|------------------------------|----------------|
| [2.5.6](#256-2025-12-23)     | December 2025  |
| [2.5.5](#255-2024-06-18)     | June 2024      |
| [2.5.4](#254-2024-02-22)     | February 2024  |
| [2.5.3](#253-2024-02-21)     | February 2024  |
| [2.5.2](#252-2023-01-12)     | January 2023   |
| [2.5.1](#251-2023-01-06)     | January 2023   |
| [2.5.0](#250-2023-01-06)     | January 2023   |
| [2.4.0](#240-2022-03-30)     | March 2022     |
| [2.3.3](#233-2021-11-16)     | November 2021  |
| [2.3.2](#232-2021-08-28)     | August 2021    |
| [2.3.1](#231-2021-05-19)     | May 2021       |
| [2.3.0](#230-2021-05-10)     | May 2021       |
| [2.2.0](#220-2021-02-27)     | February 2021  |
| [2.1.0](#210-2021-01-15)     | January 2021   |
| [2.0.3](#203-2020-11-05)     | November 2020  |
| [2.0.2](#202-2020-09-28)     | September 2020 |
| [2.0.1](#201-2020-09-28)     | September 2020 |
| [**2.0.0**](#200-2020-09-25) | September 2020 |


## [2.5.6](https://github.com/socketio/socket.io/compare/socket.io-adapter@2.5.5...socket.io-adapter@2.5.6) (2025-12-23)

This release contains a bump of:

- `ws` from `~8.17.1` to `~8.18.3`
- `debug` from `~4.3.1` to `~4.4.1`



## [2.5.5](https://github.com/socketio/socket.io-adapter/compare/2.5.4...2.5.5) (2024-06-18)

This release contains a bump of the `ws` dependency, which includes an important [security fix](https://github.com/websockets/ws/commit/e55e5106f10fcbaac37cfa89759e4cc0d073a52c).

Advisory: https://github.com/advisories/GHSA-3h5v-q93c-6h6q



## [2.5.4](https://github.com/socketio/socket.io-adapter/compare/2.5.3...2.5.4) (2024-02-22)


### Bug Fixes

* ensure the order of the commands ([a13f35f](https://github.com/socketio/socket.io-adapter/commit/a13f35f0e6b85bbba07f99ee2440e914f1429d83))
* **types:** ensure compatibility with TypeScript < 4.5 ([ca397f3](https://github.com/socketio/socket.io-adapter/commit/ca397f3afe06ed9390db52b70a506a9721e091d8))



## [2.5.3](https://github.com/socketio/socket.io-adapter/compare/2.5.2...2.5.3) (2024-02-21)

Two abstract classes were imported from the [Redis adapter repository](https://github.com/socketio/socket.io-redis-adapter/blob/bd32763043a2eb79a21dffd8820f20e598348adf/lib/cluster-adapter.ts):

- the `ClusterAdapter` class, which manages the messages sent between the server instances of the cluster
- the `ClusterAdapterWithHeartbeat` class, which extends the `ClusterAdapter` and adds a heartbeat mechanism in order to check the healthiness of the other instances

Other adapters can then just extend those classes and only have to implement the pub/sub mechanism (and not the internal chit-chat protocol):

```js
class MyAdapter extends ClusterAdapterWithHeartbeat {
  constructor(nsp, pubSub, opts) {
    super(nsp, opts);
    this.pubSub = pubSub;
    pubSub.subscribe("main-channel", (message) => this.onMessage(message));
    pubSub.subscribe("specific-channel#" + this.uid, (response) => this.onResponse(response));
  }

  doPublish(message) {
    return this.pubSub.publish("main-channel", message);
  }

  doPublishResponse(requesterUid, response) {
    return this.pubSub.publish("specific-channel#" + requesterUid, response);
  }
}
```

Besides, the number of "timeout reached: only x responses received out of y" errors (which can happen when a server instance leaves the cluster) should be greatly reduced by [this commit](https://github.com/socketio/socket.io-adapter/commit/0e23ff0cc671e3186510f7cfb8a4c1147457296f).


### Bug Fixes

* **cluster:** fix count in fetchSockets() method ([80af4e9](https://github.com/socketio/socket.io-adapter/commit/80af4e939c9caf89b0234ba1e676a3887c8d0ce6))
* **cluster:** notify the other nodes when closing ([0e23ff0](https://github.com/socketio/socket.io-adapter/commit/0e23ff0cc671e3186510f7cfb8a4c1147457296f))


### Performance Improvements

* **cluster:** use timer.refresh() ([d99a71b](https://github.com/socketio/socket.io-adapter/commit/d99a71b5588f53f0b181eee989ab2ac939f965db))



## [2.5.2](https://github.com/socketio/socket.io-adapter/compare/2.5.1...2.5.2) (2023-01-12)

The `ws` dependency was moved from `peerDependencies` to `dependencies`, in order to prevent issues like [this](https://github.com/socketio/socket.io-redis-adapter/issues/478).



## [2.5.1](https://github.com/socketio/socket.io-adapter/compare/2.5.0...2.5.1) (2023-01-06)


### Bug Fixes

* properly precompute the WebSocket frames ([99b0f18](https://github.com/socketio/socket.io-adapter/commit/99b0f188194b58a213682d564607913a447279e3))



## [2.5.0](https://github.com/socketio/socket.io-adapter/compare/2.4.0...2.5.0) (2023-01-06)


### Features

* implement connection state recovery ([f529412](https://github.com/socketio/socket.io-adapter/commit/f5294126a8feec1906bca439443c3864415415fb))


### Performance Improvements

* precompute the WebSocket frames when broadcasting ([5f7b47d](https://github.com/socketio/socket.io-adapter/commit/5f7b47d40f9daabe4e3c321eda620bbadfe5ce96))



## [2.4.0](https://github.com/socketio/socket.io-adapter/compare/2.3.3...2.4.0) (2022-03-30)


### Features

* broadcast and expect multiple acks ([a7f1c90](https://github.com/socketio/socket.io-adapter/commit/a7f1c90a322241ffaca96ddc42f204d79bc514b5))
* notify listeners for each outgoing packet ([38ee887](https://github.com/socketio/socket.io-adapter/commit/38ee887fefa8288f3a3468292c17fe7d5ca57ffc))



## [2.3.3](https://github.com/socketio/socket.io-adapter/compare/2.3.2...2.3.3) (2021-11-16)


### Bug Fixes

* fix broadcasting volatile packets with binary attachments ([88eee59](https://github.com/socketio/socket.io-adapter/commit/88eee5948aba94f999405239025f29c754a002e2))



## [2.3.2](https://github.com/socketio/socket.io-adapter/compare/2.3.1...2.3.2) (2021-08-28)


### Bug Fixes

* fix race condition when leaving rooms ([#74](https://github.com/socketio/socket.io-adapter/issues/74)) ([912e13a](https://github.com/socketio/socket.io-adapter/commit/912e13ad30bd584e2ece747be96a1ba0669dd874))


## [2.3.1](https://github.com/socketio/socket.io-adapter/compare/2.3.0...2.3.1) (2021-05-19)


### Bug Fixes

* restore compatibility with binary parsers ([a33e42b](https://github.com/socketio/socket.io-adapter/commit/a33e42bb7b935ccdd3688b4c305714b791ade0db))


## [2.3.0](https://github.com/socketio/socket.io-adapter/compare/2.2.0...2.3.0) (2021-05-10)


### Features

* add a serverSideEmit empty function ([c4cbd4b](https://github.com/socketio/socket.io-adapter/commit/c4cbd4ba2d8997f9ab8e06cfb631c8f9a43d16f1))
* add support for the "wsPreEncoded" writing option ([5579d40](https://github.com/socketio/socket.io-adapter/commit/5579d40c24d15f69e44246f788fb93beb367f994))


## [2.2.0](https://github.com/socketio/socket.io-adapter/compare/2.1.0...2.2.0) (2021-02-27)


### Features

* add some utility methods ([1c9827e](https://github.com/socketio/socket.io-adapter/commit/1c9827ec1136e24094295907efaf4d4e6c2fef2f))
* allow excluding all sockets in a room ([#66](https://github.com/socketio/socket.io-adapter/issues/66)) ([985bb41](https://github.com/socketio/socket.io-adapter/commit/985bb41fa2c04f17f1cf3a17c14ab9acde8947f7))


## [2.1.0](https://github.com/socketio/socket.io-adapter/compare/2.0.3...2.1.0) (2021-01-15)


### Features

* add room events ([155fa63](https://github.com/socketio/socket.io-adapter/commit/155fa6333a504036e99a33667dc0397f6aede25e))
* make rooms and sids public ([313c5a9](https://github.com/socketio/socket.io-adapter/commit/313c5a9fb60d913cd3a866001d67516399d8ee2f))


## [2.0.3](https://github.com/socketio/socket.io-adapter/compare/1.1.2...2.0.3) (2020-11-05)

### Features

* add init() and close() methods ([2e023bf](https://github.com/socketio/socket.io-adapter/commit/2e023bf2b651e543a34147fab19497fbdb8bdb72))
* use ES6 Sets and Maps ([53ed3f4](https://github.com/socketio/socket.io-adapter/commit/53ed3f4099c073546c66d911a95171adcefc524c))

### Bug Fixes

* Encoder#encode() is now synchronous ([c043650](https://github.com/socketio/socket.io-adapter/commit/c043650f1c6e58b20364383103314ddc733e4615))



## [2.0.3-rc2](https://github.com/socketio/socket.io-adapter/compare/2.0.3-rc1...2.0.3-rc2) (2020-10-20)


### Features

* add init() and close() methods ([2e023bf](https://github.com/socketio/socket.io-adapter/commit/2e023bf2b651e543a34147fab19497fbdb8bdb72))



## [2.0.3-rc1](https://github.com/socketio/socket.io-adapter/compare/2.0.2...2.0.3-rc1) (2020-10-15)



## [2.0.2](https://github.com/socketio/socket.io-adapter/compare/2.0.1...2.0.2) (2020-09-28)

The dist/ directory was not up-to-date when publishing the previous version...



## [2.0.1](https://github.com/socketio/socket.io-adapter/compare/2.0.0...2.0.1) (2020-09-28)


### Bug Fixes

* Encoder#encode() is now synchronous ([c043650](https://github.com/socketio/socket.io-adapter/commit/c043650f1c6e58b20364383103314ddc733e4615))



## [2.0.0](https://github.com/socketio/socket.io-adapter/compare/1.1.2...2.0.0) (2020-09-25)


### Features

* use ES6 Sets and Maps ([53ed3f4](https://github.com/socketio/socket.io-adapter/commit/53ed3f4099c073546c66d911a95171adcefc524c))
