chore(release): 4.6.0

Diff: https://github.com/socketio/socket.io/compare/4.5.4...4.6.0

.github/ISSUE_TEMPLATE/bug_report.md

@@ -2,7 +2,7 @@
 name: Bug report
 about: Create a report to help us improve
 title: ''
-labels: 'bug'
+labels: 'to triage'
 assignees: ''
 
 ---

.github/workflows/ci.yml

@@ -6,21 +6,31 @@ on:
   schedule:
     - cron: '0 0 * * 0'
 
+permissions:
+  contents: read
+
 jobs:
   test-node:
     runs-on: ubuntu-latest
+    timeout-minutes: 10
 
     strategy:
       matrix:
-        node-version: [10.x, 12.x, 14.x, 15.x]
+        node-version: [12, 14, 16]
 
     steps:
-      - uses: actions/checkout@v2
+      - name: Checkout repository
+        uses: actions/checkout@v3
+
       - name: Use Node.js ${{ matrix.node-version }}
-        uses: actions/setup-node@v1
+        uses: actions/setup-node@v3
         with:
           node-version: ${{ matrix.node-version }}
-      - run: npm ci
-      - run: npm test
+
+      - name: Install dependencies
+        run: npm ci
+
+      - name: Run tests
+        run: npm test
         env:
           CI: true

CHANGELOG.md

@@ -1,3 +1,471 @@
+# History
+
+## 2023
+
+- [4.6.0](#460-2023-02-07) (Feb 2023)
+
+## 2022
+
+- [4.5.4](#454-2022-11-22) (Nov 2022)
+- [4.5.3](#453-2022-10-15) (Oct 2022)
+- [4.5.2](#452-2022-09-02) (Sep 2022)
+- [2.5.0](#250-2022-06-26) (Jun 2022) (from the [2.x](https://github.com/socketio/socket.io/tree/2.x) branch)
+- [4.5.1](#451-2022-05-17) (May 2022)
+- [4.5.0](#450-2022-04-23) (Apr 2022)
+- [4.4.1](#441-2022-01-06) (Jan 2022)
+
+## 2021
+
+- [4.4.0](#440-2021-11-18) (Nov 2021)
+- [4.3.2](#432-2021-11-08) (Nov 2021)
+- [4.3.1](#431-2021-10-16) (Oct 2021)
+- [4.3.0](#430-2021-10-14) (Oct 2021)
+- [4.2.0](#420-2021-08-30) (Aug 2021)
+- [4.1.3](#413-2021-07-10) (Jul 2021)
+- [4.1.2](#412-2021-05-17) (May 2021)
+- [4.1.1](#411-2021-05-11) (May 2021)
+- [4.1.0](#410-2021-05-11) (May 2021)
+- [4.0.2](#402-2021-05-06) (May 2021)
+- [4.0.1](#401-2021-03-31) (Mar 2021)
+- [**4.0.0**](#400-2021-03-10) (Mar 2021)
+- [3.1.2](#312-2021-02-26) (Feb 2021)
+- [3.1.1](#311-2021-02-03) (Feb 2021)
+- [3.1.0](#310-2021-01-15) (Jan 2021)
+- [2.4.1](#241-2021-01-07) (Jan 2021) (from the [2.x](https://github.com/socketio/socket.io/tree/2.x) branch)
+- [3.0.5](#305-2021-01-05) (Jan 2021)
+- [2.4.0](#240-2021-01-04) (Jan 2021) (from the [2.x](https://github.com/socketio/socket.io/tree/2.x) branch)
+
+## 2020
+
+- [3.0.4](#304-2020-12-07) (Dec 2020)
+- [3.0.3](#303-2020-11-19) (Nov 2020)
+- [3.0.2](#302-2020-11-17) (Nov 2020)
+- [3.0.1](#301-2020-11-09) (Nov 2020)
+- [**3.0.0**](#300-2020-11-05) (Nov 2020)
+
+## 2019
+
+- [2.3.0](#230-2019-09-20) (Sep 2019)
+
+## 2018
+
+- [2.2.0](#220-2018-11-29) (Nov 2018)
+- [2.1.1](#211-2018-05-17) (May 2018)
+- [2.1.0](#210-2018-03-29) (Mar 2018)
+
+
+# Release notes
+
+# [4.6.0](https://github.com/socketio/socket.io/compare/4.5.4...4.6.0) (2023-02-07)
+
+
+### Bug Fixes
+
+* add timeout method to remote socket ([#4558](https://github.com/socketio/socket.io/issues/4558)) ([0c0eb00](https://github.com/socketio/socket.io/commit/0c0eb0016317218c2be3641e706cfaa9bea39a2d))
+* **typings:** properly type emits with timeout ([f3ada7d](https://github.com/socketio/socket.io/commit/f3ada7d8ccc02eeced2b9b9ac8e4bc921eb630d2))
+
+
+### Features
+
+#### Promise-based acknowledgements
+
+This commit adds some syntactic sugar around acknowledgements:
+
+- `emitWithAck()`
+
+```js
+try {
+  const responses = await io.timeout(1000).emitWithAck("some-event");
+  console.log(responses); // one response per client
+} catch (e) {
+  // some clients did not acknowledge the event in the given delay
+}
+
+io.on("connection", async (socket) => {
+    // without timeout
+  const response = await socket.emitWithAck("hello", "world");
+
+  // with a specific timeout
+  try {
+    const response = await socket.timeout(1000).emitWithAck("hello", "world");
+  } catch (err) {
+    // the client did not acknowledge the event in the given delay
+  }
+});
+```
+
+- `serverSideEmitWithAck()`
+
+```js
+try {
+  const responses = await io.timeout(1000).serverSideEmitWithAck("some-event");
+  console.log(responses); // one response per server (except itself)
+} catch (e) {
+  // some servers did not acknowledge the event in the given delay
+}
+```
+
+Added in [184f3cf](https://github.com/socketio/socket.io/commit/184f3cf7af57acc4b0948eee307f25f8536eb6c8).
+
+#### Connection state recovery
+
+This feature allows a client to reconnect after a temporary disconnection and restore its state:
+
+- id
+- rooms
+- data
+- missed packets
+
+Usage:
+
+```js
+import { Server } from "socket.io";
+
+const io = new Server({
+  connectionStateRecovery: {
+    // default values
+    maxDisconnectionDuration: 2 * 60 * 1000,
+    skipMiddlewares: true,
+  },
+});
+
+io.on("connection", (socket) => {
+  console.log(socket.recovered); // whether the state was recovered or not
+});
+```
+
+Here's how it works:
+
+- the server sends a session ID during the handshake (which is different from the current `id` attribute, which is public and can be freely shared)
+- the server also includes an offset in each packet (added at the end of the data array, for backward compatibility)
+- upon temporary disconnection, the server stores the client state for a given delay (implemented at the adapter level)
+- upon reconnection, the client sends both the session ID and the last offset it has processed, and the server tries to restore the state
+
+The in-memory adapter already supports this feature, and we will soon update the Postgres and MongoDB adapters. We will also create a new adapter based on [Redis Streams](https://redis.io/docs/data-types/streams/), which will support this feature.
+
+Added in [54d5ee0](https://github.com/socketio/socket.io/commit/54d5ee05a684371191e207b8089f09fc24eb5107).
+
+#### Compatibility (for real) with Express middlewares
+
+This feature implements middlewares at the Engine.IO level, because Socket.IO middlewares are meant for namespace authorization and are not executed during a classic HTTP request/response cycle.
+
+Syntax:
+
+```js
+io.engine.use((req, res, next) => {
+  // do something
+
+  next();
+});
+
+// with express-session
+import session from "express-session";
+
+io.engine.use(session({
+  secret: "keyboard cat",
+  resave: false,
+  saveUninitialized: true,
+  cookie: { secure: true }
+}));
+
+// with helmet
+import helmet from "helmet";
+
+io.engine.use(helmet());
+```
+
+A workaround was possible by using the allowRequest option and the "headers" event, but this feels way cleaner and works with upgrade requests too.
+
+Added in [24786e7](https://github.com/socketio/engine.io/commit/24786e77c5403b1c4b5a2bc84e2af06f9187f74a).
+
+#### Error details in the disconnecting and disconnect events
+
+The `disconnect` event will now contain additional details about the disconnection reason.
+
+```js
+io.on("connection", (socket) => {
+  socket.on("disconnect", (reason, description) => {
+    console.log(description);
+  });
+});
+```
+
+Added in [8aa9499](https://github.com/socketio/socket.io/commit/8aa94991cee5518567d6254eec04b23f81510257).
+
+#### Automatic removal of empty child namespaces
+
+This commit adds a new option, "cleanupEmptyChildNamespaces". With this option enabled (disabled by default), when a socket disconnects from a dynamic namespace and if there are no other sockets connected to it then the namespace will be cleaned up and its adapter will be closed. 
+
+```js
+import { createServer } from "node:http";
+import { Server } from "socket.io";
+
+const httpServer = createServer();
+const io = new Server(httpServer, {
+  cleanupEmptyChildNamespaces: true
+});
+```
+
+Added in [5d9220b](https://github.com/socketio/socket.io/commit/5d9220b69adf73e086c27bbb63a4976b348f7c4c).
+
+#### A new "addTrailingSlash" option
+
+The trailing slash which was added by default can now be disabled:
+
+```js
+import { createServer } from "node:http";
+import { Server } from "socket.io";
+
+const httpServer = createServer();
+const io = new Server(httpServer, {
+  addTrailingSlash: false
+});
+```
+
+In the example above, the clients can omit the trailing slash and use `/socket.io` instead of `/socket.io/`.
+
+Added in [d0fd474](https://github.com/socketio/engine.io/commit/d0fd4746afa396297f07bb62e539b0c1c4018d7c).
+
+### Performance Improvements
+
+* precompute the WebSocket frames when broadcasting ([da2b542](https://github.com/socketio/socket.io/commit/da2b54279749adc5279c9ac4742b01b36c01cff0))
+
+
+### Dependencies
+
+- [`engine.io@~6.4.0`](https://github.com/socketio/engine.io/releases/tag/6.4.0) ([diff](https://github.com/socketio/engine.io/compare/6.2.0...6.2.1))
+- [`ws@~8.11.0`](https://github.com/websockets/ws/releases/tag/8.11.0) ([diff](https://github.com/websockets/ws/compare/8.2.3...8.11.0))
+
+
+## [4.5.4](https://github.com/socketio/socket.io/compare/4.5.3...4.5.4) (2022-11-22)
+
+This release contains a bump of:
+
+- `engine.io` in order to fix [CVE-2022-41940](https://github.com/socketio/engine.io/security/advisories/GHSA-r7qp-cfhv-p84w)
+- `socket.io-parser` in order to fix [CVE-2022-2421](https://github.com/advisories/GHSA-qm95-pgcg-qqfq).
+
+### Dependencies
+
+- [`engine.io@~6.2.1`](https://github.com/socketio/engine.io/releases/tag/6.2.1) ([diff](https://github.com/socketio/engine.io/compare/6.2.0...6.2.1))
+- [`ws@~8.2.3`](https://github.com/websockets/ws/releases/tag/8.2.3) (no change)
+
+
+
+## [4.5.3](https://github.com/socketio/socket.io/compare/4.5.2...4.5.3) (2022-10-15)
+
+
+### Bug Fixes
+
+* **typings:** accept an HTTP2 server in the constructor ([d3d0a2d](https://github.com/socketio/socket.io/commit/d3d0a2d5beaff51fd145f810bcaf6914213f8a06))
+* **typings:** apply types to "io.timeout(...).emit()" calls ([e357daf](https://github.com/socketio/socket.io/commit/e357daf5858560bc84e7e50cd36f0278d6721ea1))
+
+
+
+## [4.5.2](https://github.com/socketio/socket.io/compare/4.5.1...4.5.2) (2022-09-02)
+
+
+### Bug Fixes
+
+* prevent the socket from joining a room after disconnection ([18f3fda](https://github.com/socketio/socket.io/commit/18f3fdab12947a9fee3e9c37cfc1da97027d1473))
+* **uws:** prevent the server from crashing after upgrade ([ba497ee](https://github.com/socketio/socket.io/commit/ba497ee3eb52c4abf1464380d015d8c788714364))
+
+
+
+# [2.5.0](https://github.com/socketio/socket.io/compare/2.4.1...2.5.0) (2022-06-26)
+
+⚠️ WARNING ⚠️
+
+The default value of the maxHttpBufferSize option has been decreased from 100 MB to 1 MB, in order to prevent attacks by denial of service.
+
+Security advisory: [GHSA-j4f2-536g-r55m](https://github.com/advisories/GHSA-j4f2-536g-r55m)
+
+
+### Bug Fixes
+
+* fix race condition in dynamic namespaces ([05e1278](https://github.com/socketio/socket.io/commit/05e1278cfa99f3ecf3f8f0531ffe57d850e9a05b))
+* ignore packet received after disconnection ([22d4bdf](https://github.com/socketio/socket.io/commit/22d4bdf00d1a03885dc0171125faddfaef730066))
+* only set 'connected' to true after middleware execution ([226cc16](https://github.com/socketio/socket.io/commit/226cc16165f9fe60f16ff4d295fb91c8971cde35))
+* prevent the socket from joining a room after disconnection ([f223178](https://github.com/socketio/socket.io/commit/f223178eb655a7713303b21a78f9ef9e161d6458))
+
+
+
+## [4.5.1](https://github.com/socketio/socket.io/compare/4.5.0...4.5.1) (2022-05-17)
+
+
+### Bug Fixes
+
+* forward the local flag to the adapter when using fetchSockets() ([30430f0](https://github.com/socketio/socket.io/commit/30430f0985f8e7c49394543d4c84913b6a15df60))
+* **typings:** add HTTPS server to accepted types ([#4351](https://github.com/socketio/socket.io/issues/4351)) ([9b43c91](https://github.com/socketio/socket.io/commit/9b43c9167cff817c60fa29dbda2ef7cd938aff51))
+
+
+
+# [4.5.0](https://github.com/socketio/socket.io/compare/4.4.1...4.5.0) (2022-04-23)
+
+
+### Bug Fixes
+
+* **typings:** ensure compatibility with TypeScript 3.x ([#4259](https://github.com/socketio/socket.io/issues/4259)) ([02c87a8](https://github.com/socketio/socket.io/commit/02c87a85614e217b8e7b93753f315790ae9d99f6))
+
+
+### Features
+
+* add support for catch-all listeners for outgoing packets ([531104d](https://github.com/socketio/socket.io/commit/531104d332690138b7aab84d5583d6204132c8b4))
+
+This is similar to `onAny()`, but for outgoing packets.
+
+Syntax:
+
+```js
+socket.onAnyOutgoing((event, ...args) => {
+  console.log(event);
+});
+```
+
+* broadcast and expect multiple acks ([8b20457](https://github.com/socketio/socket.io/commit/8b204570a94979bbec307f23ca078f30f5cf07b0))
+
+Syntax:
+
+```js
+io.timeout(1000).emit("some-event", (err, responses) => {
+  // ...
+});
+```
+
+* add the "maxPayload" field in the handshake details ([088dcb4](https://github.com/socketio/engine.io/commit/088dcb4dff60df39785df13d0a33d3ceaa1dff38))
+
+So that clients in HTTP long-polling can decide how many packets they have to send to stay under the maxHttpBufferSize
+value.
+
+This is a backward compatible change which should not mandate a new major revision of the protocol (we stay in v4), as
+we only add a field in the JSON-encoded handshake data:
+
+```
+0{"sid":"lv_VI97HAXpY6yYWAAAC","upgrades":["websocket"],"pingInterval":25000,"pingTimeout":5000,"maxPayload":1000000}
+```
+
+
+
+## [4.4.1](https://github.com/socketio/socket.io/compare/4.4.0...4.4.1) (2022-01-06)
+
+
+### Bug Fixes
+
+* **types:** make `RemoteSocket.data` type safe ([#4234](https://github.com/socketio/socket.io/issues/4234)) ([770ee59](https://github.com/socketio/socket.io/commit/770ee5949fb47c2556876c622f06c862573657d6))
+* **types:** pass `SocketData` type to custom namespaces ([#4233](https://github.com/socketio/socket.io/issues/4233)) ([f2b8de7](https://github.com/socketio/socket.io/commit/f2b8de71919e1b4d3e57f15a459972c1d1064787))
+
+
+
+# [4.4.0](https://github.com/socketio/socket.io/compare/4.3.2...4.4.0) (2021-11-18)
+
+
+### Bug Fixes
+
+* only set 'connected' to true after middleware execution ([02b0f73](https://github.com/socketio/socket.io/commit/02b0f73e2c64b09c72c5fbf7dc5f059557bdbe50))
+
+
+### Features
+
+* add an implementation based on uWebSockets.js ([c0d8c5a](https://github.com/socketio/socket.io/commit/c0d8c5ab234d0d2bef0d0dec472973cc9662f647))
+* add timeout feature ([f0ed42f](https://github.com/socketio/socket.io/commit/f0ed42f18cabef20ad976aeec37077b6bf3837a5))
+* add type information to `socket.data` ([#4159](https://github.com/socketio/socket.io/issues/4159)) ([fe8730c](https://github.com/socketio/socket.io/commit/fe8730ca0f15bc92d5de81cf934c89c76d6af329))
+
+
+
+## [4.3.2](https://github.com/socketio/socket.io/compare/4.3.1...4.3.2) (2021-11-08)
+
+
+### Bug Fixes
+
+* fix race condition in dynamic namespaces ([#4137](https://github.com/socketio/socket.io/issues/4137)) ([9d86397](https://github.com/socketio/socket.io/commit/9d86397243bcbb5775a29d96e5ef03e17148a8e7))
+
+
+## [4.3.1](https://github.com/socketio/socket.io/compare/4.3.0...4.3.1) (2021-10-16)
+
+
+### Bug Fixes
+
+* fix server attachment ([#4127](https://github.com/socketio/socket.io/issues/4127)) ([0ef2a4d](https://github.com/socketio/socket.io/commit/0ef2a4d02c9350aff163df9cb61aece89c4dac0f))
+
+
+# [4.3.0](https://github.com/socketio/socket.io/compare/4.2.0...4.3.0) (2021-10-14)
+
+
+### Bug Fixes
+
+* **typings:** add name field to cookie option ([#4099](https://github.com/socketio/socket.io/issues/4099)) ([033c5d3](https://github.com/socketio/socket.io/commit/033c5d399a2b985afad32c1e4b0c16d764e248cd))
+* send volatile packets with binary attachments ([dc81fcf](https://github.com/socketio/socket.io/commit/dc81fcf461cfdbb5b34b1a5a96b84373754047d5))
+
+
+### Features
+
+* serve ESM bundle ([60edecb](https://github.com/socketio/socket.io/commit/60edecb3bd33801803cdcba0aefbafa381a2abb3))
+
+
+# [4.2.0](https://github.com/socketio/socket.io/compare/4.1.3...4.2.0) (2021-08-30)
+
+
+### Bug Fixes
+
+* **typings:** allow async listener in typed events ([ccfd8ca](https://github.com/socketio/socket.io/commit/ccfd8caba6d38b7ba6c5114bd8179346ed07671c))
+
+
+### Features
+
+* ignore the query string when serving client JavaScript ([#4024](https://github.com/socketio/socket.io/issues/4024)) ([24fee27](https://github.com/socketio/socket.io/commit/24fee27ba36485308f8e995879c10931532c814e))
+
+
+## [4.1.3](https://github.com/socketio/socket.io/compare/4.1.2...4.1.3) (2021-07-10)
+
+
+### Bug Fixes
+
+* fix io.except() method ([94e27cd](https://github.com/socketio/socket.io/commit/94e27cd072c8a4eeb9636f6ffbb7a21d382f36b0))
+* remove x-sourcemap header ([a4dffc6](https://github.com/socketio/socket.io/commit/a4dffc6527f412d51a786ae5bf2e9080fe1ca63c))
+
+
+## [4.1.2](https://github.com/socketio/socket.io/compare/4.1.1...4.1.2) (2021-05-17)
+
+
+### Bug Fixes
+
+* **typings:** ensure compatibility with TypeScript 3.x ([0cb6ac9](https://github.com/socketio/socket.io/commit/0cb6ac95b49a27483b6f1b6402fa54b35f82e36f))
+* ensure compatibility with previous versions of the adapter ([a2cf248](https://github.com/socketio/socket.io/commit/a2cf2486c366cb62293101c10520c57f6984a3fc))
+
+
+## [4.1.1](https://github.com/socketio/socket.io/compare/4.1.0...4.1.1) (2021-05-11)
+
+
+### Bug Fixes
+
+* **typings:** properly type server-side events ([b84ed1e](https://github.com/socketio/socket.io/commit/b84ed1e41c9053792caf58974c5de9395bfd509f))
+* **typings:** properly type the adapter attribute ([891b187](https://github.com/socketio/socket.io/commit/891b1870e92d1ec38910f03bb839817e2d6be65a))
+
+
+# [4.1.0](https://github.com/socketio/socket.io/compare/4.0.2...4.1.0) (2021-05-11)
+
+
+### Features
+
+* add support for inter-server communication ([93cce05](https://github.com/socketio/socket.io/commit/93cce05fb3faf91f21fa71212275c776aa161107))
+* notify upon namespace creation ([499c892](https://github.com/socketio/socket.io/commit/499c89250d2db1ab7725ab2b74840e188c267c46))
+* add a "connection_error" event ([7096e98](https://github.com/socketio/engine.io/commit/7096e98a02295a62c8ea2aa56461d4875887092d), from `engine.io`)
+* add the "initial_headers" and "headers" events ([2527543](https://github.com/socketio/engine.io/commit/252754353a0e88eb036ebb3082e9d6a9a5f497db), from `engine.io`)
+
+
+### Performance Improvements
+
+* add support for the "wsPreEncoded" writing option ([dc381b7](https://github.com/socketio/socket.io/commit/dc381b72c6b2f8172001dedd84116122e4cc95b3))
+
+
+## [4.0.2](https://github.com/socketio/socket.io/compare/4.0.1...4.0.2) (2021-05-06)
+
+
+### Bug Fixes
+
+* **typings:** make "engine" attribute public ([b81ce4c](https://github.com/socketio/socket.io/commit/b81ce4c9d0b00666361498e2ba5e0d007d5860b8))
+* properly export the Socket class ([d65b6ee](https://github.com/socketio/socket.io/commit/d65b6ee84c8e91deb61c3c1385eb19afa196a909))
+
+
 ## [4.0.1](https://github.com/socketio/socket.io/compare/4.0.0...4.0.1) (2021-03-31)
 
 
@@ -57,6 +525,16 @@
 * allow integers as event names ([1c220dd](https://github.com/socketio/socket.io-parser/commit/1c220ddbf45ea4b44bc8dbf6f9ae245f672ba1b9))
 
 
+
+## [2.4.1](https://github.com/socketio/socket.io/compare/2.4.0...2.4.1) (2021-01-07)
+
+
+### Reverts
+
+* fix(security): do not allow all origins by default ([a169050](https://github.com/socketio/socket.io/commit/a1690509470e9dd5559cec4e60908ca6c23e9ba0))
+
+
+
 ## [3.0.5](https://github.com/socketio/socket.io/compare/3.0.4...3.0.5) (2021-01-05)
 
 
@@ -70,6 +548,17 @@
 * restore the socket middleware functionality ([bf54327](https://github.com/socketio/socket.io/commit/bf5432742158e4d5ba2722cff4a614967dffa5b9))
 
 
+
+# [2.4.0](https://github.com/socketio/socket.io/compare/2.3.0...2.4.0) (2021-01-04)
+
+
+### Bug Fixes
+
+* **security:** do not allow all origins by default ([f78a575](https://github.com/socketio/socket.io/commit/f78a575f66ab693c3ea96ea88429ddb1a44c86c7))
+* properly overwrite the query sent in the handshake ([d33a619](https://github.com/socketio/socket.io/commit/d33a619905a4905c153d4fec337c74da5b533a9e))
+
+
+
 ## [3.0.4](https://github.com/socketio/socket.io/compare/3.0.3...3.0.4) (2020-12-07)
 
 
@@ -355,3 +844,78 @@ io.of("/admin").use((socket, next) => {
 
 This method was kept for backward-compatibility with pre-1.0 versions.
 
+
+
+# [2.3.0](https://github.com/socketio/socket.io/compare/2.2.0...2.3.0) (2019-09-20)
+
+This release mainly contains a bump of the `engine.io` and `ws` packages, but no additional features.
+
+
+
+# [2.2.0](https://github.com/socketio/socket.io/compare/2.1.1...2.2.0) (2018-11-29)
+
+### Features
+
+- add cache-control header when serving the client source ([#2907](https://github.com/socketio/socket.io/pull/2907)) ([b00ae50](https://github.com/socketio/socket.io/commit/b00ae50be65d1bc88fa95145f1c486a6886a6b76))
+
+### Bug fixes
+
+- throw an error when trying to access the clients of a dynamic namespace ([#3355](https://github.com/socketio/socket.io/pull/3355)) ([a7fbd1a](https://github.com/socketio/socket.io/commit/a7fbd1ac4a47cafd832fc62e371754df924c5903))
+
+
+
+# [2.1.1](https://github.com/socketio/socket.io/compare/2.1.0...2.1.1) (2018-05-17)
+
+### Features
+
+- add local flag to the socket object ([#3129](https://github.com/socketio/socket.io/pull/3219)) ([1decae3](https://github.com/socketio/socket.io/commit/1decae341c80c0417b32d3124ca30c005240b48a))
+
+```js
+socket.local.to('room101').emit(/* */);
+```
+
+
+# [2.1.0](https://github.com/socketio/socket.io/compare/2.1.1...2.2.0) (2018-03-29)
+
+### Features
+
+- add a 'binary' flag ([#3185](https://github.com/socketio/socket.io/pull/3185)) ([f48a06c](https://github.com/socketio/socket.io/commit/f48a06c040280b44f90fd225c888910544fd63b5))
+
+```js
+// by default, the object is recursively scanned to check whether it contains some binary data
+// in the following example, the check is skipped in order to improve performance
+socket.binary(false).emit('plain-object', object);
+
+// it also works at the namespace level
+io.binary(false).emit('plain-object', object);
+```
+
+- add support for dynamic namespaces ([#3195](https://github.com/socketio/socket.io/pull/3195)) ([c0c79f0](https://github.com/socketio/socket.io/commit/c0c79f019e7138194e438339f8192705957c8ec3))
+
+```js
+io.of(/^\/dynamic-\d+$/).on('connect', (socket) => {
+  // socket.nsp.name = '/dynamic-101'
+});
+
+// client-side
+const client = require('socket.io-client')('/dynamic-101');
+```
+
+### Bug fixes
+
+- properly emit 'connect' when using a custom namespace ([#3197](https://github.com/socketio/socket.io/pull/3197)) ([f4fc517](https://github.com/socketio/socket.io/commit/f4fc517e0fe25866c95b584291487b8cbdff889d))
+- include the protocol in the origins check ([#3198](https://github.com/socketio/socket.io/pull/3198)) ([1f1d64b](https://github.com/socketio/socket.io/commit/1f1d64bab61a273712a199591a3f76210d8c0959))
+
+### Important note :warning: from Engine.IO [3.2.0 release](https://github.com/socketio/engine.io/releases/tag/3.2.0)
+
+There are two non-breaking changes that are somehow quite important:
+
+- `ws` was reverted as the default wsEngine (https://github.com/socketio/engine.io/pull/550), as there was several blocking issues with `uws`. You can still use `uws` by running `npm install uws --save` in your project and using the `wsEngine` option:
+```js
+var engine = require('engine.io');
+var server = engine.listen(3000, {
+  wsEngine: 'uws'
+});
+```
+
+- `pingTimeout` now defaults to 5 seconds (instead of 60 seconds): https://github.com/socketio/engine.io/pull/551

Readme.md

@@ -1,9 +1,7 @@
 # socket.io
-[![Run on Repl.it](https://repl.it/badge/github/socketio/socket.io)](https://repl.it/github/socketio/socket.io)
+[![Run on Repl.it](https://repl.it/badge/github/socketio/socket.io)](https://replit.com/@socketio/socketio-minimal-example)
 [![Backers on Open Collective](https://opencollective.com/socketio/backers/badge.svg)](#backers) [![Sponsors on Open Collective](https://opencollective.com/socketio/sponsors/badge.svg)](#sponsors)
 [![Build Status](https://github.com/socketio/socket.io/workflows/CI/badge.svg)](https://github.com/socketio/socket.io/actions)
-[![Dependency Status](https://david-dm.org/socketio/socket.io.svg)](https://david-dm.org/socketio/socket.io)
-[![devDependency Status](https://david-dm.org/socketio/socket.io/dev-status.svg)](https://david-dm.org/socketio/socket.io#info=devDependencies)
 [![NPM version](https://badge.fury.io/js/socket.io.svg)](https://www.npmjs.com/package/socket.io)
 ![Downloads](https://img.shields.io/npm/dm/socket.io.svg?style=flat)
 [![](https://slackin-socketio.now.sh/badge.svg)](https://slackin-socketio.now.sh)
@@ -22,7 +20,8 @@ Some implementations in other languages are also available:
 - [Swift](https://github.com/socketio/socket.io-client-swift)
 - [Dart](https://github.com/rikulo/socket.io-client-dart)
 - [Python](https://github.com/miguelgrinberg/python-socketio)
-- [.Net](https://github.com/Quobject/SocketIoClientDotNet)
+- [.NET](https://github.com/doghappy/socket.io-client-csharp)
+- [Rust](https://github.com/1c3t3a/rust-socketio)
 
 Its main features are:
 
@@ -115,6 +114,14 @@ io.on('connection', client => { ... });
 io.listen(3000);
 ```
 
+### Module syntax 
+
+```js
+import { Server } from "socket.io";
+const io = new Server(server);
+io.listen(3000);
+```
+
 ### In conjunction with Express
 
 Starting with **3.0**, express applications have become request handler

SECURITY.md

@@ -0,0 +1,22 @@
+# Security Policy
+
+## Supported Versions
+
+| Version | Supported          |
+|---------|--------------------|
+| 4.x     | :white_check_mark: |
+| 3.x     | :white_check_mark: |
+| 2.4.x   | :white_check_mark: |
+| < 2.4.0 | :x:                |
+
+## Reporting a Vulnerability
+
+To report a security vulnerability in this package, please send an email to [@darrachequesne](https://github.com/darrachequesne) (see address in profile) describing the vulnerability and how to reproduce it.
+
+We will get back to you as soon as possible and publish a fix if necessary.
+
+:warning: IMPORTANT :warning: please do not create an issue in this repository, as attackers might take advantage of it. Thank you in advance for your responsible disclosure.
+
+## History
+
+No security vulnerability were reported yet.

examples/basic-crud-application/README.md

@@ -0,0 +1,26 @@
+# Basic CRUD application with Socket.IO
+
+Please read the related [guide](https://socket.io/get-started/basic-crud-application/).
+
+This repository contains several implementations of the server:
+
+| Directory                  | Language   | Database                                                                           | Cluster?                                                                                   |
+|----------------------------|------------|------------------------------------------------------------------------------------|--------------------------------------------------------------------------------------------|
+| `server/`                  | TypeScript | in-memory                                                                          | No                                                                                         |
+| `server-postgres-cluster/` | JavaScript | Postgres, with the [Postgres adapter](https://socket.io/docs/v4/postgres-adapter/) | Yes, with the [`@socket.io/sticky`](https://github.com/socketio/socket.io-sticky) module)  |
+
+## Running the frontend
+
+```
+cd angular-client
+npm install
+npm start
+```
+
+### Running the server
+
+```
+cd server
+npm install
+npm start
+```

examples/basic-crud-application/angular-client/.browserslistrc

@@ -0,0 +1,17 @@
+# This file is used by the build system to adjust CSS and JS output to support the specified browsers below.
+# For additional information regarding the format and rule options, please see:
+# https://github.com/browserslist/browserslist#queries
+
+# For the full list of supported browsers by the Angular framework, please see:
+# https://angular.io/guide/browser-support
+
+# You can see what browsers were selected by your queries by running:
+#   npx browserslist
+
+last 1 Chrome version
+last 1 Firefox version
+last 2 Edge major versions
+last 2 Safari major versions
+last 2 iOS major versions
+Firefox ESR
+not IE 11 # Angular supports IE 11 only as an opt-in. To opt-in, remove the 'not' prefix on this line.

examples/basic-crud-application/angular-client/.editorconfig

@@ -0,0 +1,16 @@
+# Editor configuration, see https://editorconfig.org
+root = true
+
+[*]
+charset = utf-8
+indent_style = space
+indent_size = 2
+insert_final_newline = true
+trim_trailing_whitespace = true
+
+[*.ts]
+quote_type = single
+
+[*.md]
+max_line_length = off
+trim_trailing_whitespace = false

examples/basic-crud-application/angular-client/.gitignore

@@ -0,0 +1,46 @@
+# See http://help.github.com/ignore-files/ for more about ignoring files.
+
+# compiled output
+/dist
+/tmp
+/out-tsc
+# Only exists if Bazel was run
+/bazel-out
+
+# dependencies
+/node_modules
+
+# profiling files
+chrome-profiler-events*.json
+speed-measure-plugin*.json
+
+# IDEs and editors
+/.idea
+.project
+.classpath
+.c9/
+*.launch
+.settings/
+*.sublime-workspace
+
+# IDE - VSCode
+.vscode/*
+!.vscode/settings.json
+!.vscode/tasks.json
+!.vscode/launch.json
+!.vscode/extensions.json
+.history/*
+
+# misc
+/.sass-cache
+/connect.lock
+/coverage
+/libpeerconnection.log
+npm-debug.log
+yarn-error.log
+testem.log
+/typings
+
+# System Files
+.DS_Store
+Thumbs.db

examples/basic-crud-application/angular-client/README.md

@@ -0,0 +1,31 @@
+# Angular TodoMVC + Socket.IO
+
+This project was generated with [Angular CLI](https://github.com/angular/angular-cli) version 11.0.4.
+
+Inspired from the [TodoMVC](http://todomvc.com/) [angular example](https://github.com/tastejs/todomvc/tree/master/examples/angular2).
+
+![demo](assets/demo.gif)
+
+## Development server
+
+Run `ng serve` for a dev server. Navigate to `http://localhost:4200/`. The app will automatically reload if you change any of the source files.
+
+## Code scaffolding
+
+Run `ng generate component component-name` to generate a new component. You can also use `ng generate directive|pipe|service|class|guard|interface|enum|module`.
+
+## Build
+
+Run `ng build` to build the project. The build artifacts will be stored in the `dist/` directory. Use the `--prod` flag for a production build.
+
+## Running unit tests
+
+Run `ng test` to execute the unit tests via [Karma](https://karma-runner.github.io).
+
+## Running end-to-end tests
+
+Run `ng e2e` to execute the end-to-end tests via [Protractor](http://www.protractortest.org/).
+
+## Further help
+
+To get more help on the Angular CLI use `ng help` or go check out the [Angular CLI Overview and Command Reference](https://angular.io/cli) page.

examples/basic-crud-application/angular-client/angular.json

@@ -0,0 +1,128 @@
+{
+  "$schema": "./node_modules/@angular/cli/lib/config/schema.json",
+  "version": 1,
+  "newProjectRoot": "projects",
+  "projects": {
+    "angular-todomvc": {
+      "projectType": "application",
+      "schematics": {
+        "@schematics/angular:application": {
+          "strict": true
+        }
+      },
+      "root": "",
+      "sourceRoot": "src",
+      "prefix": "app",
+      "architect": {
+        "build": {
+          "builder": "@angular-devkit/build-angular:browser",
+          "options": {
+            "outputPath": "dist/angular-todomvc",
+            "index": "src/index.html",
+            "main": "src/main.ts",
+            "polyfills": "src/polyfills.ts",
+            "tsConfig": "tsconfig.app.json",
+            "aot": true,
+            "assets": [
+              "src/favicon.ico",
+              "src/assets"
+            ],
+            "styles": [
+              "src/styles.css"
+            ],
+            "scripts": []
+          },
+          "configurations": {
+            "production": {
+              "fileReplacements": [
+                {
+                  "replace": "src/environments/environment.ts",
+                  "with": "src/environments/environment.prod.ts"
+                }
+              ],
+              "optimization": true,
+              "outputHashing": "all",
+              "sourceMap": false,
+              "namedChunks": false,
+              "extractLicenses": true,
+              "vendorChunk": false,
+              "buildOptimizer": true,
+              "budgets": [
+                {
+                  "type": "initial",
+                  "maximumWarning": "500kb",
+                  "maximumError": "1mb"
+                },
+                {
+                  "type": "anyComponentStyle",
+                  "maximumWarning": "2kb",
+                  "maximumError": "4kb"
+                }
+              ]
+            }
+          }
+        },
+        "serve": {
+          "builder": "@angular-devkit/build-angular:dev-server",
+          "options": {
+            "browserTarget": "angular-todomvc:build"
+          },
+          "configurations": {
+            "production": {
+              "browserTarget": "angular-todomvc:build:production"
+            }
+          }
+        },
+        "extract-i18n": {
+          "builder": "@angular-devkit/build-angular:extract-i18n",
+          "options": {
+            "browserTarget": "angular-todomvc:build"
+          }
+        },
+        "test": {
+          "builder": "@angular-devkit/build-angular:karma",
+          "options": {
+            "main": "src/test.ts",
+            "polyfills": "src/polyfills.ts",
+            "tsConfig": "tsconfig.spec.json",
+            "karmaConfig": "karma.conf.js",
+            "assets": [
+              "src/favicon.ico",
+              "src/assets"
+            ],
+            "styles": [
+              "src/styles.css"
+            ],
+            "scripts": []
+          }
+        },
+        "lint": {
+          "builder": "@angular-devkit/build-angular:tslint",
+          "options": {
+            "tsConfig": [
+              "tsconfig.app.json",
+              "tsconfig.spec.json",
+              "e2e/tsconfig.json"
+            ],
+            "exclude": [
+              "**/node_modules/**"
+            ]
+          }
+        },
+        "e2e": {
+          "builder": "@angular-devkit/build-angular:protractor",
+          "options": {
+            "protractorConfig": "e2e/protractor.conf.js",
+            "devServerTarget": "angular-todomvc:serve"
+          },
+          "configurations": {
+            "production": {
+              "devServerTarget": "angular-todomvc:serve:production"
+            }
+          }
+        }
+      }
+    }
+  },
+  "defaultProject": "angular-todomvc"
+}

examples/basic-crud-application/angular-client/e2e/protractor.conf.js

@@ -0,0 +1,37 @@
+// @ts-check
+// Protractor configuration file, see link for more information
+// https://github.com/angular/protractor/blob/master/lib/config.ts
+
+const { SpecReporter, StacktraceOption } = require('jasmine-spec-reporter');
+
+/**
+ * @type { import("protractor").Config }
+ */
+exports.config = {
+  allScriptsTimeout: 11000,
+  specs: [
+    './src/**/*.e2e-spec.ts'
+  ],
+  capabilities: {
+    browserName: 'chrome'
+  },
+  directConnect: true,
+  SELENIUM_PROMISE_MANAGER: false,
+  baseUrl: 'http://localhost:4200/',
+  framework: 'jasmine',
+  jasmineNodeOpts: {
+    showColors: true,
+    defaultTimeoutInterval: 30000,
+    print: function() {}
+  },
+  onPrepare() {
+    require('ts-node').register({
+      project: require('path').join(__dirname, './tsconfig.json')
+    });
+    jasmine.getEnv().addReporter(new SpecReporter({
+      spec: {
+        displayStacktrace: StacktraceOption.PRETTY
+      }
+    }));
+  }
+};

examples/basic-crud-application/angular-client/e2e/src/app.e2e-spec.ts

@@ -0,0 +1,23 @@
+import { AppPage } from './app.po';
+import { browser, logging } from 'protractor';
+
+describe('workspace-project App', () => {
+  let page: AppPage;
+
+  beforeEach(() => {
+    page = new AppPage();
+  });
+
+  it('should display welcome message', async () => {
+    await page.navigateTo();
+    expect(await page.getTitleText()).toEqual('angular-todomvc app is running!');
+  });
+
+  afterEach(async () => {
+    // Assert that there are no errors emitted from the browser
+    const logs = await browser.manage().logs().get(logging.Type.BROWSER);
+    expect(logs).not.toContain(jasmine.objectContaining({
+      level: logging.Level.SEVERE,
+    } as logging.Entry));
+  });
+});

examples/basic-crud-application/angular-client/e2e/src/app.po.ts

@@ -0,0 +1,11 @@
+import { browser, by, element } from 'protractor';
+
+export class AppPage {
+  async navigateTo(): Promise<unknown> {
+    return browser.get(browser.baseUrl);
+  }
+
+  async getTitleText(): Promise<string> {
+    return element(by.css('app-root .content span')).getText();
+  }
+}

examples/basic-crud-application/angular-client/e2e/tsconfig.json

@@ -0,0 +1,13 @@
+/* To learn more about this file see: https://angular.io/config/tsconfig. */
+{
+  "extends": "../tsconfig.json",
+  "compilerOptions": {
+    "outDir": "../out-tsc/e2e",
+    "module": "commonjs",
+    "target": "es2018",
+    "types": [
+      "jasmine",
+      "node"
+    ]
+  }
+}

examples/basic-crud-application/angular-client/karma.conf.js

@@ -0,0 +1,44 @@
+// Karma configuration file, see link for more information
+// https://karma-runner.github.io/1.0/config/configuration-file.html
+
+module.exports = function (config) {
+  config.set({
+    basePath: '',
+    frameworks: ['jasmine', '@angular-devkit/build-angular'],
+    plugins: [
+      require('karma-jasmine'),
+      require('karma-chrome-launcher'),
+      require('karma-jasmine-html-reporter'),
+      require('karma-coverage'),
+      require('@angular-devkit/build-angular/plugins/karma')
+    ],
+    client: {
+      jasmine: {
+        // you can add configuration options for Jasmine here
+        // the possible options are listed at https://jasmine.github.io/api/edge/Configuration.html
+        // for example, you can disable the random execution with `random: false`
+        // or set a specific seed with `seed: 4321`
+      },
+      clearContext: false // leave Jasmine Spec Runner output visible in browser
+    },
+    jasmineHtmlReporter: {
+      suppressAll: true // removes the duplicated traces
+    },
+    coverageReporter: {
+      dir: require('path').join(__dirname, './coverage/angular-todomvc'),
+      subdir: '.',
+      reporters: [
+        { type: 'html' },
+        { type: 'text-summary' }
+      ]
+    },
+    reporters: ['progress', 'kjhtml'],
+    port: 9876,
+    colors: true,
+    logLevel: config.LOG_INFO,
+    autoWatch: true,
+    browsers: ['Chrome'],
+    singleRun: false,
+    restartOnFileChange: true
+  });
+};

examples/basic-crud-application/angular-client/package.json

@@ -0,0 +1,46 @@
+{
+  "name": "angular-todomvc",
+  "version": "0.0.0",
+  "scripts": {
+    "ng": "ng",
+    "start": "ng serve",
+    "build": "ng build",
+    "test": "ng test",
+    "lint": "ng lint",
+    "e2e": "ng e2e"
+  },
+  "private": true,
+  "dependencies": {
+    "@angular/animations": "~11.0.4",
+    "@angular/common": "~11.0.4",
+    "@angular/compiler": "~11.0.4",
+    "@angular/core": "~11.0.4",
+    "@angular/forms": "~11.0.4",
+    "@angular/platform-browser": "~11.0.4",
+    "@angular/platform-browser-dynamic": "~11.0.4",
+    "@angular/router": "~11.0.4",
+    "rxjs": "~6.6.0",
+    "socket.io-client": "^4.0.0",
+    "tslib": "^2.0.0",
+    "zone.js": "~0.10.2"
+  },
+  "devDependencies": {
+    "@angular-devkit/build-angular": "~0.1100.4",
+    "@angular/cli": "~11.0.4",
+    "@angular/compiler-cli": "~11.0.4",
+    "@types/jasmine": "~3.6.0",
+    "@types/node": "^12.11.1",
+    "codelyzer": "^6.0.0",
+    "jasmine-core": "~3.6.0",
+    "jasmine-spec-reporter": "~5.0.0",
+    "karma": "~5.1.0",
+    "karma-chrome-launcher": "~3.1.0",
+    "karma-coverage": "~2.0.3",
+    "karma-jasmine": "~4.0.0",
+    "karma-jasmine-html-reporter": "~1.5.0",
+    "protractor": "~7.0.0",
+    "ts-node": "~8.3.0",
+    "tslint": "~6.1.0",
+    "typescript": "~4.0.2"
+  }
+}

examples/basic-crud-application/angular-client/src/app/app.component.html

@@ -0,0 +1,23 @@
+<section class="todoapp">
+  <header class="header">
+    <h1>todos</h1>
+    <input class="new-todo" placeholder="What needs to be done?" autofocus="" [(ngModel)]="newTodoText" (keyup.enter)="addTodo()">
+  </header>
+  <section class="main" *ngIf="todoStore.todos.length > 0">
+    <input id="toggle-all" class="toggle-all" type="checkbox" *ngIf="todoStore.todos.length" #toggleall [checked]="todoStore.allCompleted()" (click)="todoStore.setAllTo(toggleall.checked)">
+    <ul class="todo-list">
+      <li *ngFor="let todo of todoStore.todos" [class.completed]="todo.completed" [class.editing]="todo.editing">
+        <div class="view">
+          <input class="toggle" type="checkbox" (click)="toggleCompletion(todo)" [checked]="todo.completed">
+          <label (dblclick)="editTodo(todo)">{{todo.title}}</label>
+          <button class="destroy" (click)="remove(todo)"></button>
+        </div>
+        <input class="edit" *ngIf="todo.editing" [value]="todo.title" #editedtodo (blur)="stopEditing(todo, editedtodo.value)" (keyup.enter)="updateEditingTodo(todo, editedtodo.value)" (keyup.escape)="cancelEditingTodo(todo)">
+      </li>
+    </ul>
+  </section>
+  <footer class="footer" *ngIf="todoStore.todos.length > 0">
+    <span class="todo-count"><strong>{{todoStore.getRemaining().length}}</strong> {{todoStore.getRemaining().length == 1 ? 'item' : 'items'}} left</span>
+    <button class="clear-completed" *ngIf="todoStore.getCompleted().length > 0" (click)="removeCompleted()">Clear completed</button>
+  </footer>
+</section>

examples/basic-crud-application/angular-client/src/app/app.component.spec.ts

@@ -0,0 +1,31 @@
+import { TestBed } from '@angular/core/testing';
+import { AppComponent } from './app.component';
+
+describe('AppComponent', () => {
+  beforeEach(async () => {
+    await TestBed.configureTestingModule({
+      declarations: [
+        AppComponent
+      ],
+    }).compileComponents();
+  });
+
+  it('should create the app', () => {
+    const fixture = TestBed.createComponent(AppComponent);
+    const app = fixture.componentInstance;
+    expect(app).toBeTruthy();
+  });
+
+  it(`should have as title 'angular-todomvc'`, () => {
+    const fixture = TestBed.createComponent(AppComponent);
+    const app = fixture.componentInstance;
+    expect(app.title).toEqual('angular-todomvc');
+  });
+
+  it('should render title', () => {
+    const fixture = TestBed.createComponent(AppComponent);
+    fixture.detectChanges();
+    const compiled = fixture.nativeElement;
+    expect(compiled.querySelector('.content span').textContent).toContain('angular-todomvc app is running!');
+  });
+});

examples/basic-crud-application/angular-client/src/app/app.component.ts

@@ -0,0 +1,59 @@
+import { Component } from '@angular/core';
+import { TodoStore, Todo } from './store';
+
+@Component({
+  selector: 'app-root',
+  templateUrl: './app.component.html',
+  styleUrls: ['./app.component.css']
+})
+export class AppComponent {
+  todoStore: TodoStore;
+  newTodoText = '';
+
+  constructor(todoStore: TodoStore) {
+    this.todoStore = todoStore;
+  }
+
+  stopEditing(todo: Todo, editedTitle: string) {
+    todo.title = editedTitle;
+    todo.editing = false;
+  }
+
+  cancelEditingTodo(todo: Todo) {
+    todo.editing = false;
+  }
+
+  updateEditingTodo(todo: Todo, editedTitle: string) {
+    editedTitle = editedTitle.trim();
+    todo.editing = false;
+
+    if (editedTitle.length === 0) {
+      return this.todoStore.remove(todo);
+    }
+
+    todo.title = editedTitle;
+  }
+
+  editTodo(todo: Todo) {
+    todo.editing = true;
+  }
+
+  removeCompleted() {
+    this.todoStore.removeCompleted();
+  }
+
+  toggleCompletion(todo: Todo) {
+    this.todoStore.toggleCompletion(todo);
+  }
+
+  remove(todo: Todo){
+    this.todoStore.remove(todo);
+  }
+
+  addTodo() {
+    if (this.newTodoText.trim().length) {
+      this.todoStore.add(this.newTodoText);
+      this.newTodoText = '';
+    }
+  }
+}

examples/basic-crud-application/angular-client/src/app/app.module.ts

@@ -0,0 +1,19 @@
+import { BrowserModule } from '@angular/platform-browser';
+import { NgModule } from '@angular/core';
+
+import { AppComponent } from './app.component';
+import { TodoStore } from './store';
+import { FormsModule } from "@angular/forms";
+
+@NgModule({
+  declarations: [
+    AppComponent
+  ],
+  imports: [
+    BrowserModule,
+    FormsModule
+  ],
+  providers: [TodoStore],
+  bootstrap: [AppComponent]
+})
+export class AppModule { }

examples/basic-crud-application/angular-client/src/app/store.ts

@@ -0,0 +1,140 @@
+import { io, Socket } from "socket.io-client";
+import { ClientEvents, ServerEvents } from "../../../server/lib/events";
+import { environment } from '../environments/environment';
+
+export interface Todo {
+  id: string,
+  title: string,
+  completed: boolean,
+  editing: boolean,
+  synced: boolean
+}
+
+const mapTodo = (todo: any) => {
+  return {
+    ...todo,
+    editing: false,
+    synced: true
+  }
+}
+
+export class TodoStore {
+  public todos: Array<Todo> = [];
+  private socket: Socket<ServerEvents, ClientEvents>;
+
+  constructor() {
+    this.socket = io(environment.serverUrl);
+
+    this.socket.on("connect", () => {
+      this.socket.emit("todo:list", (res) => {
+        if ("error" in res) {
+          // handle the error
+          return;
+        }
+        this.todos = res.data.map(mapTodo);
+      });
+    });
+
+    this.socket.on("todo:created", (todo) => {
+      this.todos.push(mapTodo(todo));
+    });
+
+    this.socket.on("todo:updated", (todo) => {
+      const existingTodo = this.todos.find(t => {
+        return t.id === todo.id
+      });
+      if (existingTodo) {
+        existingTodo.title = todo.title;
+        existingTodo.completed = todo.completed;
+      }
+    });
+
+    this.socket.on("todo:deleted", (id) => {
+      const index = this.todos.findIndex(t => {
+        return t.id === id
+      });
+      if (index !== -1) {
+        this.todos.splice(index, 1);
+      }
+    })
+  }
+
+  private getWithCompleted(completed: boolean) {
+    return this.todos.filter((todo: Todo) => todo.completed === completed);
+  }
+
+  allCompleted() {
+    return this.todos.length === this.getCompleted().length;
+  }
+
+  setAllTo(completed: boolean) {
+    this.todos.forEach(todo => {
+      todo.completed = completed;
+      todo.synced = false;
+      this.socket.emit("todo:update", todo, (res) => {
+        if (res && "error" in res) {
+          // handle the error
+          return;
+        }
+        todo.synced = true;
+      });
+    });
+  }
+
+  removeCompleted() {
+    this.getCompleted().forEach((todo) => {
+      this.socket.emit("todo:delete", todo.id, (res) => {
+        if (res && "error" in res) {
+          // handle the error
+        }
+      });
+    })
+    this.todos = this.getRemaining();
+  }
+
+  getRemaining() {
+    return this.getWithCompleted(false);
+  }
+
+  getCompleted() {
+    return this.getWithCompleted(true);
+  }
+
+  toggleCompletion(todo: Todo) {
+    todo.completed = !todo.completed;
+    todo.synced = false;
+    this.socket.emit("todo:update", todo, (res) => {
+      if (res && "error" in res) {
+        // handle the error
+        return;
+      }
+      todo.synced = true;
+    })
+  }
+
+  remove(todo: Todo) {
+    this.todos.splice(this.todos.indexOf(todo), 1);
+    this.socket.emit("todo:delete", todo.id, (res) => {
+      if (res && "error" in res) {
+        // handle the error
+      }
+    });
+  }
+
+  add(title: string) {
+    this.socket.emit("todo:create", { title, completed: false }, (res) => {
+      if ("error" in res) {
+        // handle the error
+        return;
+      }
+      this.todos.push({
+        id: res.data,
+        title,
+        completed: false,
+        editing: false,
+        synced: true
+      });
+    });
+  }
+}
+

examples/basic-crud-application/angular-client/src/environments/environment.prod.ts

@@ -0,0 +1,4 @@
+export const environment = {
+  production: true,
+  serverUrl: "https://my-custom-domain.com"
+};

examples/basic-crud-application/angular-client/src/environments/environment.ts

@@ -0,0 +1,17 @@
+// This file can be replaced during build by using the `fileReplacements` array.
+// `ng build --prod` replaces `environment.ts` with `environment.prod.ts`.
+// The list of file replacements can be found in `angular.json`.
+
+export const environment = {
+  production: false,
+  serverUrl: "http://localhost:3000"
+};
+
+/*
+ * For easier debugging in development mode, you can import the following file
+ * to ignore zone related error stack frames such as `zone.run`, `zoneDelegate.invokeTask`.
+ *
+ * This import should be commented out in production mode because it will have a negative impact
+ * on performance if an error is thrown.
+ */
+// import 'zone.js/dist/zone-error';  // Included with Angular CLI.

examples/basic-crud-application/angular-client/src/index.html

@@ -0,0 +1,13 @@
+<!doctype html>
+<html lang="en">
+<head>
+  <meta charset="utf-8">
+  <title>Angular Todo MVC</title>
+  <base href="/">
+  <meta name="viewport" content="width=device-width, initial-scale=1">
+  <link rel="icon" type="image/x-icon" href="favicon.ico">
+</head>
+<body>
+  <app-root></app-root>
+</body>
+</html>

examples/basic-crud-application/angular-client/src/main.ts

@@ -0,0 +1,12 @@
+import { enableProdMode } from '@angular/core';
+import { platformBrowserDynamic } from '@angular/platform-browser-dynamic';
+
+import { AppModule } from './app/app.module';
+import { environment } from './environments/environment';
+
+if (environment.production) {
+  enableProdMode();
+}
+
+platformBrowserDynamic().bootstrapModule(AppModule)
+  .catch(err => console.error(err));

examples/basic-crud-application/angular-client/src/polyfills.ts

@@ -0,0 +1,63 @@
+/**
+ * This file includes polyfills needed by Angular and is loaded before the app.
+ * You can add your own extra polyfills to this file.
+ *
+ * This file is divided into 2 sections:
+ *   1. Browser polyfills. These are applied before loading ZoneJS and are sorted by browsers.
+ *   2. Application imports. Files imported after ZoneJS that should be loaded before your main
+ *      file.
+ *
+ * The current setup is for so-called "evergreen" browsers; the last versions of browsers that
+ * automatically update themselves. This includes Safari >= 10, Chrome >= 55 (including Opera),
+ * Edge >= 13 on the desktop, and iOS 10 and Chrome on mobile.
+ *
+ * Learn more in https://angular.io/guide/browser-support
+ */
+
+/***************************************************************************************************
+ * BROWSER POLYFILLS
+ */
+
+/** IE11 requires the following for NgClass support on SVG elements */
+// import 'classlist.js';  // Run `npm install --save classlist.js`.
+
+/**
+ * Web Animations `@angular/platform-browser/animations`
+ * Only required if AnimationBuilder is used within the application and using IE/Edge or Safari.
+ * Standard animation support in Angular DOES NOT require any polyfills (as of Angular 6.0).
+ */
+// import 'web-animations-js';  // Run `npm install --save web-animations-js`.
+
+/**
+ * By default, zone.js will patch all possible macroTask and DomEvents
+ * user can disable parts of macroTask/DomEvents patch by setting following flags
+ * because those flags need to be set before `zone.js` being loaded, and webpack
+ * will put import in the top of bundle, so user need to create a separate file
+ * in this directory (for example: zone-flags.ts), and put the following flags
+ * into that file, and then add the following code before importing zone.js.
+ * import './zone-flags';
+ *
+ * The flags allowed in zone-flags.ts are listed here.
+ *
+ * The following flags will work for all browsers.
+ *
+ * (window as any).__Zone_disable_requestAnimationFrame = true; // disable patch requestAnimationFrame
+ * (window as any).__Zone_disable_on_property = true; // disable patch onProperty such as onclick
+ * (window as any).__zone_symbol__UNPATCHED_EVENTS = ['scroll', 'mousemove']; // disable patch specified eventNames
+ *
+ *  in IE/Edge developer tools, the addEventListener will also be wrapped by zone.js
+ *  with the following flag, it will bypass `zone.js` patch for IE/Edge
+ *
+ *  (window as any).__Zone_enable_cross_context_check = true;
+ *
+ */
+
+/***************************************************************************************************
+ * Zone JS is required by default for Angular itself.
+ */
+import 'zone.js/dist/zone';  // Included with Angular CLI.
+
+
+/***************************************************************************************************
+ * APPLICATION IMPORTS
+ */

examples/basic-crud-application/angular-client/src/styles.css

@@ -0,0 +1,381 @@
+/* imported from node_modules/todomvc-app-css/index.css */
+html,
+body {
+  margin: 0;
+  padding: 0;
+}
+
+button {
+  margin: 0;
+  padding: 0;
+  border: 0;
+  background: none;
+  font-size: 100%;
+  vertical-align: baseline;
+  font-family: inherit;
+  font-weight: inherit;
+  color: inherit;
+  -webkit-appearance: none;
+  appearance: none;
+  -webkit-font-smoothing: antialiased;
+  -moz-osx-font-smoothing: grayscale;
+}
+
+body {
+  font: 14px 'Helvetica Neue', Helvetica, Arial, sans-serif;
+  line-height: 1.4em;
+  background: #f5f5f5;
+  color: #111111;
+  min-width: 230px;
+  max-width: 550px;
+  margin: 0 auto;
+  -webkit-font-smoothing: antialiased;
+  -moz-osx-font-smoothing: grayscale;
+  font-weight: 300;
+}
+
+:focus {
+  outline: 0;
+}
+
+.hidden {
+  display: none;
+}
+
+.todoapp {
+  background: #fff;
+  margin: 130px 0 40px 0;
+  position: relative;
+  box-shadow: 0 2px 4px 0 rgba(0, 0, 0, 0.2),
+  0 25px 50px 0 rgba(0, 0, 0, 0.1);
+}
+
+.todoapp input::-webkit-input-placeholder {
+  font-style: italic;
+  font-weight: 300;
+  color: rgba(0, 0, 0, 0.4);
+}
+
+.todoapp input::-moz-placeholder {
+  font-style: italic;
+  font-weight: 300;
+  color: rgba(0, 0, 0, 0.4);
+}
+
+.todoapp input::input-placeholder {
+  font-style: italic;
+  font-weight: 300;
+  color: rgba(0, 0, 0, 0.4);
+}
+
+.todoapp h1 {
+  position: absolute;
+  top: -140px;
+  width: 100%;
+  font-size: 80px;
+  font-weight: 200;
+  text-align: center;
+  color: #b83f45;
+  -webkit-text-rendering: optimizeLegibility;
+  -moz-text-rendering: optimizeLegibility;
+  text-rendering: optimizeLegibility;
+}
+
+.new-todo,
+.edit {
+  position: relative;
+  margin: 0;
+  width: 100%;
+  font-size: 24px;
+  font-family: inherit;
+  font-weight: inherit;
+  line-height: 1.4em;
+  color: inherit;
+  padding: 6px;
+  border: 1px solid #999;
+  box-shadow: inset 0 -1px 5px 0 rgba(0, 0, 0, 0.2);
+  box-sizing: border-box;
+  -webkit-font-smoothing: antialiased;
+  -moz-osx-font-smoothing: grayscale;
+}
+
+.new-todo {
+  padding: 16px 16px 16px 60px;
+  border: none;
+  background: rgba(0, 0, 0, 0.003);
+  box-shadow: inset 0 -2px 1px rgba(0,0,0,0.03);
+}
+
+.main {
+  position: relative;
+  z-index: 2;
+  border-top: 1px solid #e6e6e6;
+}
+
+.toggle-all {
+  width: 1px;
+  height: 1px;
+  border: none; /* Mobile Safari */
+  opacity: 0;
+  position: absolute;
+  right: 100%;
+  bottom: 100%;
+}
+
+.toggle-all + label {
+  width: 60px;
+  height: 34px;
+  font-size: 0;
+  position: absolute;
+  top: -52px;
+  left: -13px;
+  -webkit-transform: rotate(90deg);
+  transform: rotate(90deg);
+}
+
+.toggle-all + label:before {
+  content: '❯';
+  font-size: 22px;
+  color: #e6e6e6;
+  padding: 10px 27px 10px 27px;
+}
+
+.toggle-all:checked + label:before {
+  color: #737373;
+}
+
+.todo-list {
+  margin: 0;
+  padding: 0;
+  list-style: none;
+}
+
+.todo-list li {
+  position: relative;
+  font-size: 24px;
+  border-bottom: 1px solid #ededed;
+}
+
+.todo-list li:last-child {
+  border-bottom: none;
+}
+
+.todo-list li.editing {
+  border-bottom: none;
+  padding: 0;
+}
+
+.todo-list li.editing .edit {
+  display: block;
+  width: calc(100% - 43px);
+  padding: 12px 16px;
+  margin: 0 0 0 43px;
+}
+
+.todo-list li.editing .view {
+  display: none;
+}
+
+.todo-list li .toggle {
+  text-align: center;
+  width: 40px;
+  /* auto, since non-WebKit browsers doesn't support input styling */
+  height: auto;
+  position: absolute;
+  top: 0;
+  bottom: 0;
+  margin: auto 0;
+  border: none; /* Mobile Safari */
+  -webkit-appearance: none;
+  appearance: none;
+}
+
+.todo-list li .toggle {
+  opacity: 0;
+}
+
+.todo-list li .toggle + label {
+  /*
+    Firefox requires `#` to be escaped - https://bugzilla.mozilla.org/show_bug.cgi?id=922433
+    IE and Edge requires *everything* to be escaped to render, so we do that instead of just the `#` - https://developer.microsoft.com/en-us/microsoft-edge/platform/issues/7157459/
+  */
+  background-image: url('data:image/svg+xml;utf8,%3Csvg%20xmlns%3D%22http%3A//www.w3.org/2000/svg%22%20width%3D%2240%22%20height%3D%2240%22%20viewBox%3D%22-10%20-18%20100%20135%22%3E%3Ccircle%20cx%3D%2250%22%20cy%3D%2250%22%20r%3D%2250%22%20fill%3D%22none%22%20stroke%3D%22%23ededed%22%20stroke-width%3D%223%22/%3E%3C/svg%3E');
+  background-repeat: no-repeat;
+  background-position: center left;
+}
+
+.todo-list li .toggle:checked + label {
+  background-image: url('data:image/svg+xml;utf8,%3Csvg%20xmlns%3D%22http%3A//www.w3.org/2000/svg%22%20width%3D%2240%22%20height%3D%2240%22%20viewBox%3D%22-10%20-18%20100%20135%22%3E%3Ccircle%20cx%3D%2250%22%20cy%3D%2250%22%20r%3D%2250%22%20fill%3D%22none%22%20stroke%3D%22%23bddad5%22%20stroke-width%3D%223%22/%3E%3Cpath%20fill%3D%22%235dc2af%22%20d%3D%22M72%2025L42%2071%2027%2056l-4%204%2020%2020%2034-52z%22/%3E%3C/svg%3E');
+}
+
+.todo-list li label {
+  word-break: break-all;
+  padding: 15px 15px 15px 60px;
+  display: block;
+  line-height: 1.2;
+  transition: color 0.4s;
+  font-weight: 400;
+  color: #4d4d4d;
+}
+
+.todo-list li.completed label {
+  color: #cdcdcd;
+  text-decoration: line-through;
+}
+
+.todo-list li .destroy {
+  display: none;
+  position: absolute;
+  top: 0;
+  right: 10px;
+  bottom: 0;
+  width: 40px;
+  height: 40px;
+  margin: auto 0;
+  font-size: 30px;
+  color: #cc9a9a;
+  margin-bottom: 11px;
+  transition: color 0.2s ease-out;
+}
+
+.todo-list li .destroy:hover {
+  color: #af5b5e;
+}
+
+.todo-list li .destroy:after {
+  content: '×';
+}
+
+.todo-list li:hover .destroy {
+  display: block;
+}
+
+.todo-list li .edit {
+  display: none;
+}
+
+.todo-list li.editing:last-child {
+  margin-bottom: -1px;
+}
+
+.footer {
+  padding: 10px 15px;
+  height: 20px;
+  text-align: center;
+  font-size: 15px;
+  border-top: 1px solid #e6e6e6;
+}
+
+.footer:before {
+  content: '';
+  position: absolute;
+  right: 0;
+  bottom: 0;
+  left: 0;
+  height: 50px;
+  overflow: hidden;
+  box-shadow: 0 1px 1px rgba(0, 0, 0, 0.2),
+  0 8px 0 -3px #f6f6f6,
+  0 9px 1px -3px rgba(0, 0, 0, 0.2),
+  0 16px 0 -6px #f6f6f6,
+  0 17px 2px -6px rgba(0, 0, 0, 0.2);
+}
+
+.todo-count {
+  float: left;
+  text-align: left;
+}
+
+.todo-count strong {
+  font-weight: 300;
+}
+
+.filters {
+  margin: 0;
+  padding: 0;
+  list-style: none;
+  position: absolute;
+  right: 0;
+  left: 0;
+}
+
+.filters li {
+  display: inline;
+}
+
+.filters li a {
+  color: inherit;
+  margin: 3px;
+  padding: 3px 7px;
+  text-decoration: none;
+  border: 1px solid transparent;
+  border-radius: 3px;
+}
+
+.filters li a:hover {
+  border-color: rgba(175, 47, 47, 0.1);
+}
+
+.filters li a.selected {
+  border-color: rgba(175, 47, 47, 0.2);
+}
+
+.clear-completed,
+html .clear-completed:active {
+  float: right;
+  position: relative;
+  line-height: 20px;
+  text-decoration: none;
+  cursor: pointer;
+}
+
+.clear-completed:hover {
+  text-decoration: underline;
+}
+
+.info {
+  margin: 65px auto 0;
+  color: #4d4d4d;
+  font-size: 11px;
+  text-shadow: 0 1px 0 rgba(255, 255, 255, 0.5);
+  text-align: center;
+}
+
+.info p {
+  line-height: 1;
+}
+
+.info a {
+  color: inherit;
+  text-decoration: none;
+  font-weight: 400;
+}
+
+.info a:hover {
+  text-decoration: underline;
+}
+
+/*
+	Hack to remove background from Mobile Safari.
+	Can't use it globally since it destroys checkboxes in Firefox
+*/
+@media screen and (-webkit-min-device-pixel-ratio:0) {
+  .toggle-all,
+  .todo-list li .toggle {
+    background: none;
+  }
+
+  .todo-list li .toggle {
+    height: 40px;
+  }
+}
+
+@media (max-width: 430px) {
+  .footer {
+    height: 50px;
+  }
+
+  .filters {
+    bottom: 10px;
+  }
+}

examples/basic-crud-application/angular-client/src/test.ts

@@ -0,0 +1,25 @@
+// This file is required by karma.conf.js and loads recursively all the .spec and framework files
+
+import 'zone.js/dist/zone-testing';
+import { getTestBed } from '@angular/core/testing';
+import {
+  BrowserDynamicTestingModule,
+  platformBrowserDynamicTesting
+} from '@angular/platform-browser-dynamic/testing';
+
+declare const require: {
+  context(path: string, deep?: boolean, filter?: RegExp): {
+    keys(): string[];
+    <T>(id: string): T;
+  };
+};
+
+// First, initialize the Angular testing environment.
+getTestBed().initTestEnvironment(
+  BrowserDynamicTestingModule,
+  platformBrowserDynamicTesting()
+);
+// Then we find all the tests.
+const context = require.context('./', true, /\.spec\.ts$/);
+// And load the modules.
+context.keys().map(context);

examples/basic-crud-application/angular-client/tsconfig.app.json

@@ -0,0 +1,15 @@
+/* To learn more about this file see: https://angular.io/config/tsconfig. */
+{
+  "extends": "./tsconfig.json",
+  "compilerOptions": {
+    "outDir": "./out-tsc/app",
+    "types": []
+  },
+  "files": [
+    "src/main.ts",
+    "src/polyfills.ts"
+  ],
+  "include": [
+    "src/**/*.d.ts"
+  ]
+}

examples/basic-crud-application/angular-client/tsconfig.json

@@ -0,0 +1,29 @@
+/* To learn more about this file see: https://angular.io/config/tsconfig. */
+{
+  "compileOnSave": false,
+  "compilerOptions": {
+    "baseUrl": "./",
+    "outDir": "./dist/out-tsc",
+    "forceConsistentCasingInFileNames": true,
+    "strict": true,
+    "noImplicitReturns": true,
+    "noFallthroughCasesInSwitch": true,
+    "sourceMap": true,
+    "declaration": false,
+    "downlevelIteration": true,
+    "experimentalDecorators": true,
+    "moduleResolution": "node",
+    "importHelpers": true,
+    "target": "es2015",
+    "module": "es2020",
+    "lib": [
+      "es2018",
+      "dom"
+    ]
+  },
+  "angularCompilerOptions": {
+    "strictInjectionParameters": true,
+    "strictInputAccessModifiers": true,
+    "strictTemplates": true
+  }
+}

examples/basic-crud-application/angular-client/tsconfig.spec.json

@@ -0,0 +1,18 @@
+/* To learn more about this file see: https://angular.io/config/tsconfig. */
+{
+  "extends": "./tsconfig.json",
+  "compilerOptions": {
+    "outDir": "./out-tsc/spec",
+    "types": [
+      "jasmine"
+    ]
+  },
+  "files": [
+    "src/test.ts",
+    "src/polyfills.ts"
+  ],
+  "include": [
+    "src/**/*.spec.ts",
+    "src/**/*.d.ts"
+  ]
+}

examples/basic-crud-application/angular-client/tslint.json

@@ -0,0 +1,152 @@
+{
+  "extends": "tslint:recommended",
+  "rulesDirectory": [
+    "codelyzer"
+  ],
+  "rules": {
+    "align": {
+      "options": [
+        "parameters",
+        "statements"
+      ]
+    },
+    "array-type": false,
+    "arrow-return-shorthand": true,
+    "curly": true,
+    "deprecation": {
+      "severity": "warning"
+    },
+    "eofline": true,
+    "import-blacklist": [
+      true,
+      "rxjs/Rx"
+    ],
+    "import-spacing": true,
+    "indent": {
+      "options": [
+        "spaces"
+      ]
+    },
+    "max-classes-per-file": false,
+    "max-line-length": [
+      true,
+      140
+    ],
+    "member-ordering": [
+      true,
+      {
+        "order": [
+          "static-field",
+          "instance-field",
+          "static-method",
+          "instance-method"
+        ]
+      }
+    ],
+    "no-console": [
+      true,
+      "debug",
+      "info",
+      "time",
+      "timeEnd",
+      "trace"
+    ],
+    "no-empty": false,
+    "no-inferrable-types": [
+      true,
+      "ignore-params"
+    ],
+    "no-non-null-assertion": true,
+    "no-redundant-jsdoc": true,
+    "no-switch-case-fall-through": true,
+    "no-var-requires": false,
+    "object-literal-key-quotes": [
+      true,
+      "as-needed"
+    ],
+    "quotemark": [
+      true,
+      "single"
+    ],
+    "semicolon": {
+      "options": [
+        "always"
+      ]
+    },
+    "space-before-function-paren": {
+      "options": {
+        "anonymous": "never",
+        "asyncArrow": "always",
+        "constructor": "never",
+        "method": "never",
+        "named": "never"
+      }
+    },
+    "typedef": [
+      true,
+      "call-signature"
+    ],
+    "typedef-whitespace": {
+      "options": [
+        {
+          "call-signature": "nospace",
+          "index-signature": "nospace",
+          "parameter": "nospace",
+          "property-declaration": "nospace",
+          "variable-declaration": "nospace"
+        },
+        {
+          "call-signature": "onespace",
+          "index-signature": "onespace",
+          "parameter": "onespace",
+          "property-declaration": "onespace",
+          "variable-declaration": "onespace"
+        }
+      ]
+    },
+    "variable-name": {
+      "options": [
+        "ban-keywords",
+        "check-format",
+        "allow-pascal-case"
+      ]
+    },
+    "whitespace": {
+      "options": [
+        "check-branch",
+        "check-decl",
+        "check-operator",
+        "check-separator",
+        "check-type",
+        "check-typecast"
+      ]
+    },
+    "component-class-suffix": true,
+    "contextual-lifecycle": true,
+    "directive-class-suffix": true,
+    "no-conflicting-lifecycle": true,
+    "no-host-metadata-property": true,
+    "no-input-rename": true,
+    "no-inputs-metadata-property": true,
+    "no-output-native": true,
+    "no-output-on-prefix": true,
+    "no-output-rename": true,
+    "no-outputs-metadata-property": true,
+    "template-banana-in-box": true,
+    "template-no-negated-async": true,
+    "use-lifecycle-interface": true,
+    "use-pipe-transform-interface": true,
+    "directive-selector": [
+      true,
+      "attribute",
+      "app",
+      "camelCase"
+    ],
+    "component-selector": [
+      true,
+      "element",
+      "app",
+      "kebab-case"
+    ]
+  }
+}

examples/basic-crud-application/server-postgres-cluster/README.md

@@ -0,0 +1,16 @@
+
+A basic TODO project.
+
+| Characteristic |                                                                                           |
+|----------------|-------------------------------------------------------------------------------------------|
+| Language       | plain JavaScript                                                                          |
+| Database       | Postgres, with the [Postgres adapter](https://socket.io/docs/v4/postgres-adapter/)        |
+| Cluster?       | Yes, with the [`@socket.io/sticky`](https://github.com/socketio/socket.io-sticky) module) |
+
+## Usage
+
+```
+$ docker-compose up -d
+$ npm install
+$ npm start
+```

examples/basic-crud-application/server-postgres-cluster/docker-compose.yml

@@ -0,0 +1,9 @@
+version: "3"
+
+services:
+  postgres:
+    image: postgres:12
+    ports:
+      - "5432:5432"
+    environment:
+      POSTGRES_PASSWORD: "changeit"

examples/basic-crud-application/server-postgres-cluster/lib/app.js

@@ -0,0 +1,26 @@
+import { Server } from "socket.io";
+import createTodoHandlers from "./todo-management/todo.handlers.js";
+import { setupWorker } from "@socket.io/sticky";
+import { createAdapter } from "@socket.io/postgres-adapter";
+
+export function createApplication(httpServer, components, serverOptions = {}) {
+  const io = new Server(httpServer, serverOptions);
+
+  const { createTodo, readTodo, updateTodo, deleteTodo, listTodo } =
+    createTodoHandlers(components);
+
+  io.on("connection", (socket) => {
+    socket.on("todo:create", createTodo);
+    socket.on("todo:read", readTodo);
+    socket.on("todo:update", updateTodo);
+    socket.on("todo:delete", deleteTodo);
+    socket.on("todo:list", listTodo);
+  });
+
+  // enable sticky session in the cluster (to remove in standalone mode)
+  setupWorker(io);
+
+  io.adapter(createAdapter(components.connectionPool));
+
+  return io;
+}

examples/basic-crud-application/server-postgres-cluster/lib/cluster.js

@@ -0,0 +1,28 @@
+import cluster from "cluster";
+import { createServer } from "http";
+import { setupMaster } from "@socket.io/sticky";
+import { cpus } from "os";
+
+if (cluster.isMaster) {
+  console.log(`Master ${process.pid} is running`);
+  const httpServer = createServer();
+
+  setupMaster(httpServer, {
+    loadBalancingMethod: "least-connection",
+  });
+
+  httpServer.listen(3000);
+
+  for (let i = 0; i < cpus().length; i++) {
+    cluster.fork();
+  }
+
+  cluster.on("exit", (worker) => {
+    console.log(`Worker ${worker.process.pid} died`);
+    cluster.fork();
+  });
+} else {
+  console.log(`Worker ${process.pid} started`);
+
+  import("./index.js");
+}

examples/basic-crud-application/server-postgres-cluster/lib/index.js

@@ -0,0 +1,51 @@
+import { createServer } from "http";
+import { createApplication } from "./app.js";
+import { Sequelize } from "sequelize";
+import pg from "pg";
+import { PostgresTodoRepository } from "./todo-management/todo.repository.js";
+
+const httpServer = createServer();
+
+const sequelize = new Sequelize("postgres", "postgres", "changeit", {
+  dialect: "postgres",
+});
+
+const connectionPool = new pg.Pool({
+  user: "postgres",
+  host: "localhost",
+  database: "postgres",
+  password: "changeit",
+  port: 5432,
+});
+
+createApplication(
+  httpServer,
+  {
+    connectionPool,
+    todoRepository: new PostgresTodoRepository(sequelize),
+  },
+  {
+    cors: {
+      origin: ["http://localhost:4200"],
+    },
+  }
+);
+
+const main = async () => {
+  // create the tables if they do not exist already
+  await sequelize.sync();
+
+  // create the table needed by the postgres adapter
+  await connectionPool.query(`
+    CREATE TABLE IF NOT EXISTS socket_io_attachments (
+        id          bigserial UNIQUE,
+        created_at  timestamptz DEFAULT NOW(),
+        payload     bytea
+    );
+  `);
+
+  // uncomment when running in standalone mode
+  // httpServer.listen(3000);
+};
+
+main();

examples/basic-crud-application/server-postgres-cluster/lib/todo-management/todo.handlers.js

@@ -0,0 +1,140 @@
+import { Errors, mapErrorDetails, sanitizeErrorMessage } from "../util.js";
+import { v4 as uuid } from "uuid";
+import Joi from "joi";
+
+const idSchema = Joi.string().guid({
+  version: "uuidv4",
+});
+
+const todoSchema = Joi.object({
+  id: idSchema.alter({
+    create: (schema) => schema.forbidden(),
+    update: (schema) => schema.required(),
+  }),
+  title: Joi.string().max(256).required(),
+  completed: Joi.boolean().required(),
+});
+
+export default function (components) {
+  const { todoRepository } = components;
+  return {
+    createTodo: async function (payload, callback) {
+      const socket = this;
+
+      // validate the payload
+      const { error, value } = todoSchema.tailor("create").validate(payload, {
+        abortEarly: false,
+        stripUnknown: true,
+      });
+
+      if (error) {
+        return callback({
+          error: Errors.INVALID_PAYLOAD,
+          errorDetails: mapErrorDetails(error.details),
+        });
+      }
+
+      value.id = uuid();
+
+      // persist the entity
+      try {
+        await todoRepository.save(value);
+      } catch (e) {
+        return callback({
+          error: sanitizeErrorMessage(e),
+        });
+      }
+
+      // acknowledge the creation
+      callback({
+        data: value.id,
+      });
+
+      // notify the other users
+      socket.broadcast.emit("todo:created", value);
+    },
+
+    readTodo: async function (id, callback) {
+      const { error } = idSchema.validate(id);
+
+      if (error) {
+        return callback({
+          error: Errors.ENTITY_NOT_FOUND,
+        });
+      }
+
+      try {
+        const todo = await todoRepository.findById(id);
+        callback({
+          data: todo,
+        });
+      } catch (e) {
+        callback({
+          error: sanitizeErrorMessage(e),
+        });
+      }
+    },
+
+    updateTodo: async function (payload, callback) {
+      const socket = this;
+
+      const { error, value } = todoSchema.tailor("update").validate(payload, {
+        abortEarly: false,
+        stripUnknown: true,
+      });
+
+      if (error) {
+        return callback({
+          error: Errors.INVALID_PAYLOAD,
+          errorDetails: mapErrorDetails(error.details),
+        });
+      }
+
+      try {
+        await todoRepository.save(value);
+      } catch (e) {
+        return callback({
+          error: sanitizeErrorMessage(e),
+        });
+      }
+
+      callback();
+      socket.broadcast.emit("todo:updated", value);
+    },
+
+    deleteTodo: async function (id, callback) {
+      const socket = this;
+
+      const { error } = idSchema.validate(id);
+
+      if (error) {
+        return callback({
+          error: Errors.ENTITY_NOT_FOUND,
+        });
+      }
+
+      try {
+        await todoRepository.deleteById(id);
+      } catch (e) {
+        return callback({
+          error: sanitizeErrorMessage(e),
+        });
+      }
+
+      callback();
+      socket.broadcast.emit("todo:deleted", id);
+    },
+
+    listTodo: async function (callback) {
+      try {
+        callback({
+          data: await todoRepository.findAll(),
+        });
+      } catch (e) {
+        callback({
+          error: sanitizeErrorMessage(e),
+        });
+      }
+    },
+  };
+}

examples/basic-crud-application/server-postgres-cluster/lib/todo-management/todo.repository.js

@@ -0,0 +1,74 @@
+import { Errors } from "../util.js";
+import { Model, DataTypes } from "sequelize";
+
+class CrudRepository {
+  findAll() {}
+  findById(id) {}
+  save(entity) {}
+  deleteById(id) {}
+}
+
+export class TodoRepository extends CrudRepository {}
+
+class Todo extends Model {}
+
+export class PostgresTodoRepository extends TodoRepository {
+  constructor(sequelize) {
+    super();
+    this.sequelize = sequelize;
+
+    Todo.init(
+      {
+        id: {
+          type: DataTypes.STRING,
+          primaryKey: true,
+          allowNull: false,
+        },
+        title: {
+          type: DataTypes.STRING,
+        },
+        completed: {
+          type: DataTypes.BOOLEAN,
+        },
+      },
+      {
+        sequelize,
+        tableName: "todos",
+      }
+    );
+  }
+
+  findAll() {
+    return this.sequelize.transaction((transaction) => {
+      return Todo.findAll({ transaction });
+    });
+  }
+
+  async findById(id) {
+    return this.sequelize.transaction(async (transaction) => {
+      const todo = await Todo.findByPk(id, { transaction });
+
+      if (!todo) {
+        throw Errors.ENTITY_NOT_FOUND;
+      }
+
+      return todo;
+    });
+  }
+
+  save(entity) {
+    return this.sequelize.transaction((transaction) => {
+      return Todo.upsert(entity, { transaction });
+    });
+  }
+
+  async deleteById(id) {
+    return this.sequelize.transaction(async (transaction) => {
+      const count = await Todo.destroy({ where: { id }, transaction });
+
+      if (count === 0) {
+        throw Errors.ENTITY_NOT_FOUND;
+      }
+    });
+  }
+}

examples/basic-crud-application/server-postgres-cluster/lib/util.js

@@ -0,0 +1,22 @@
+export const Errors = {
+  ENTITY_NOT_FOUND: "entity not found",
+  INVALID_PAYLOAD: "invalid payload",
+};
+
+const errorValues = Object.values(Errors);
+
+export function sanitizeErrorMessage(message) {
+  if (typeof message === "string" && errorValues.includes(message)) {
+    return message;
+  } else {
+    return "an unknown error has occurred";
+  }
+}
+
+export function mapErrorDetails(details) {
+  return details.map((item) => ({
+    message: item.message,
+    path: item.path,
+    type: item.type,
+  }));
+}

examples/basic-crud-application/server-postgres-cluster/package.json

@@ -0,0 +1,30 @@
+{
+  "name": "basic-crud-server",
+  "version": "0.0.1",
+  "description": "Server for the Basic CRUD Socket.IO example (with Postgres and multiple Socket.IO servers)",
+  "main": "lib/cluster.js",
+  "type": "module",
+  "scripts": {
+    "start": "node lib/cluster.js"
+  },
+  "repository": {
+    "type": "git",
+    "url": "git+https://github.com/socketio/socket.io.git"
+  },
+  "author": "Damien Arrachequesne <damien.arrachequesne@gmail.com>",
+  "license": "MIT",
+  "bugs": {
+    "url": "https://github.com/socketio/socket.io/issues"
+  },
+  "homepage": "https://github.com/socketio/socket.io#readme",
+  "dependencies": {
+    "@socket.io/postgres-adapter": "^0.2.0",
+    "@socket.io/sticky": "^1.0.1",
+    "joi": "^17.4.0",
+    "pg": "^8.7.3",
+    "pg-hstore": "^2.3.4",
+    "sequelize": "^6.18.0",
+    "socket.io": "^4.0.1",
+    "uuid": "^8.3.2"
+  }
+}

examples/basic-crud-application/server/lib/app.ts

@@ -0,0 +1,35 @@
+import { Server as HttpServer } from "http";
+import { Server, ServerOptions } from "socket.io";
+import { ClientEvents, ServerEvents } from "./events";
+import { TodoRepository } from "./todo-management/todo.repository";
+import createTodoHandlers from "./todo-management/todo.handlers";
+
+export interface Components {
+  todoRepository: TodoRepository;
+}
+
+export function createApplication(
+  httpServer: HttpServer,
+  components: Components,
+  serverOptions: Partial<ServerOptions> = {}
+): Server<ClientEvents, ServerEvents> {
+  const io = new Server<ClientEvents, ServerEvents>(httpServer, serverOptions);
+
+  const {
+    createTodo,
+    readTodo,
+    updateTodo,
+    deleteTodo,
+    listTodo,
+  } = createTodoHandlers(components);
+
+  io.on("connection", (socket) => {
+    socket.on("todo:create", createTodo);
+    socket.on("todo:read", readTodo);
+    socket.on("todo:update", updateTodo);
+    socket.on("todo:delete", deleteTodo);
+    socket.on("todo:list", listTodo);
+  });
+
+  return io;
+}

examples/basic-crud-application/server/lib/events.ts

@@ -0,0 +1,37 @@
+import { Todo, TodoID } from "./todo-management/todo.repository";
+import { ValidationErrorItem } from "joi";
+
+interface Error {
+  error: string;
+  errorDetails?: ValidationErrorItem[];
+}
+
+interface Success<T> {
+  data: T;
+}
+
+export type Response<T> = Error | Success<T>;
+
+export interface ServerEvents {
+  "todo:created": (todo: Todo) => void;
+  "todo:updated": (todo: Todo) => void;
+  "todo:deleted": (id: TodoID) => void;
+}
+
+export interface ClientEvents {
+  "todo:list": (callback: (res: Response<Todo[]>) => void) => void;
+
+  "todo:create": (
+    payload: Omit<Todo, "id">,
+    callback: (res: Response<TodoID>) => void
+  ) => void;
+
+  "todo:read": (id: TodoID, callback: (res: Response<Todo>) => void) => void;
+
+  "todo:update": (
+    payload: Todo,
+    callback: (res?: Response<void>) => void
+  ) => void;
+
+  "todo:delete": (id: TodoID, callback: (res?: Response<void>) => void) => void;
+}

examples/basic-crud-application/server/lib/index.ts

@@ -0,0 +1,19 @@
+import { createServer } from "http";
+import { createApplication } from "./app";
+import { InMemoryTodoRepository } from "./todo-management/todo.repository";
+
+const httpServer = createServer();
+
+createApplication(
+  httpServer,
+  {
+    todoRepository: new InMemoryTodoRepository(),
+  },
+  {
+    cors: {
+      origin: ["http://localhost:4200"],
+    },
+  }
+);
+
+httpServer.listen(3000);

examples/basic-crud-application/server/lib/todo-management/todo.handlers.ts

@@ -0,0 +1,159 @@
+import { Errors, mapErrorDetails, sanitizeErrorMessage } from "../util";
+import { v4 as uuid } from "uuid";
+import { Components } from "../app";
+import Joi = require("joi");
+import { Todo, TodoID } from "./todo.repository";
+import { ClientEvents, Response, ServerEvents } from "../events";
+import { Socket } from "socket.io";
+
+const idSchema = Joi.string().guid({
+  version: "uuidv4",
+});
+
+const todoSchema = Joi.object({
+  id: idSchema.alter({
+    create: (schema) => schema.forbidden(),
+    update: (schema) => schema.required(),
+  }),
+  title: Joi.string().max(256).required(),
+  completed: Joi.boolean().required(),
+});
+
+export default function (components: Components) {
+  const { todoRepository } = components;
+  return {
+    createTodo: async function (
+      payload: Omit<Todo, "id">,
+      callback: (res: Response<TodoID>) => void
+    ) {
+      // @ts-ignore
+      const socket: Socket<ClientEvents, ServerEvents> = this;
+
+      // validate the payload
+      const { error, value } = todoSchema.tailor("create").validate(payload, {
+        abortEarly: false,
+        stripUnknown: true,
+      });
+
+      if (error) {
+        return callback({
+          error: Errors.INVALID_PAYLOAD,
+          errorDetails: mapErrorDetails(error.details),
+        });
+      }
+
+      value.id = uuid();
+
+      // persist the entity
+      try {
+        await todoRepository.save(value);
+      } catch (e) {
+        return callback({
+          error: sanitizeErrorMessage(e),
+        });
+      }
+
+      // acknowledge the creation
+      callback({
+        data: value.id,
+      });
+
+      // notify the other users
+      socket.broadcast.emit("todo:created", value);
+    },
+
+    readTodo: async function (
+      id: TodoID,
+      callback: (res: Response<Todo>) => void
+    ) {
+      const { error } = idSchema.validate(id);
+
+      if (error) {
+        return callback({
+          error: Errors.ENTITY_NOT_FOUND,
+        });
+      }
+
+      try {
+        const todo = await todoRepository.findById(id);
+        callback({
+          data: todo,
+        });
+      } catch (e) {
+        callback({
+          error: sanitizeErrorMessage(e),
+        });
+      }
+    },
+
+    updateTodo: async function (
+      payload: Todo,
+      callback: (res?: Response<void>) => void
+    ) {
+      // @ts-ignore
+      const socket: Socket<ClientEvents, ServerEvents> = this;
+
+      const { error, value } = todoSchema.tailor("update").validate(payload, {
+        abortEarly: false,
+        stripUnknown: true,
+      });
+
+      if (error) {
+        return callback({
+          error: Errors.INVALID_PAYLOAD,
+          errorDetails: mapErrorDetails(error.details),
+        });
+      }
+
+      try {
+        await todoRepository.save(value);
+      } catch (e) {
+        return callback({
+          error: sanitizeErrorMessage(e),
+        });
+      }
+
+      callback();
+      socket.broadcast.emit("todo:updated", value);
+    },
+
+    deleteTodo: async function (
+      id: TodoID,
+      callback: (res?: Response<void>) => void
+    ) {
+      // @ts-ignore
+      const socket: Socket<ClientEvents, ServerEvents> = this;
+
+      const { error } = idSchema.validate(id);
+
+      if (error) {
+        return callback({
+          error: Errors.ENTITY_NOT_FOUND,
+        });
+      }
+
+      try {
+        await todoRepository.deleteById(id);
+      } catch (e) {
+        return callback({
+          error: sanitizeErrorMessage(e),
+        });
+      }
+
+      callback();
+      socket.broadcast.emit("todo:deleted", id);
+    },
+
+    listTodo: async function (callback: (res: Response<Todo[]>) => void) {
+      try {
+        callback({
+          data: await todoRepository.findAll(),
+        });
+      } catch (e) {
+        callback({
+          error: sanitizeErrorMessage(e),
+        });
+      }
+    },
+  };
+}

examples/basic-crud-application/server/lib/todo-management/todo.repository.ts

@@ -0,0 +1,49 @@
+import { Errors } from "../util";
+
+abstract class CrudRepository<T, ID> {
+  abstract findAll(): Promise<T[]>;
+  abstract findById(id: ID): Promise<T>;
+  abstract save(entity: T): Promise<void>;
+  abstract deleteById(id: ID): Promise<void>;
+}
+
+export type TodoID = string;
+
+export interface Todo {
+  id: TodoID;
+  completed: boolean;
+  title: string;
+}
+
+export abstract class TodoRepository extends CrudRepository<Todo, TodoID> {}
+
+export class InMemoryTodoRepository extends TodoRepository {
+  private readonly todos: Map<TodoID, Todo> = new Map();
+
+  findAll(): Promise<Todo[]> {
+    const entities = Array.from(this.todos.values());
+    return Promise.resolve(entities);
+  }
+
+  findById(id: TodoID): Promise<Todo> {
+    if (this.todos.has(id)) {
+      return Promise.resolve(this.todos.get(id)!);
+    } else {
+      return Promise.reject(Errors.ENTITY_NOT_FOUND);
+    }
+  }
+
+  save(entity: Todo): Promise<void> {
+    this.todos.set(entity.id, entity);
+    return Promise.resolve();
+  }
+
+  deleteById(id: TodoID): Promise<void> {
+    const deleted = this.todos.delete(id);
+    if (deleted) {
+      return Promise.resolve();
+    } else {
+      return Promise.reject(Errors.ENTITY_NOT_FOUND);
+    }
+  }
+}

examples/basic-crud-application/server/lib/util.ts

@@ -0,0 +1,24 @@
+import { ValidationErrorItem } from "joi";
+
+export enum Errors {
+  ENTITY_NOT_FOUND = "entity not found",
+  INVALID_PAYLOAD = "invalid payload",
+}
+
+const errorValues: string[] = Object.values(Errors);
+
+export function sanitizeErrorMessage(message: any) {
+  if (typeof message === "string" && errorValues.includes(message)) {
+    return message;
+  } else {
+    return "an unknown error has occurred";
+  }
+}
+
+export function mapErrorDetails(details: ValidationErrorItem[]) {
+  return details.map((item) => ({
+    message: item.message,
+    path: item.path,
+    type: item.type,
+  }));
+}

examples/basic-crud-application/server/package.json

@@ -0,0 +1,37 @@
+{
+  "name": "basic-crud-server",
+  "version": "0.0.1",
+  "description": "Server for the Basic CRUD Socket.IO example",
+  "main": "dist/lib/index.js",
+  "scripts": {
+    "start": "ts-node lib/index.ts",
+    "build": "tsc",
+    "test": "nyc mocha --require ts-node/register test/**/*.ts"
+  },
+  "repository": {
+    "type": "git",
+    "url": "git+https://github.com/socketio/socket.io.git"
+  },
+  "author": "Damien Arrachequesne <damien.arrachequesne@gmail.com>",
+  "license": "MIT",
+  "bugs": {
+    "url": "https://github.com/socketio/socket.io/issues"
+  },
+  "homepage": "https://github.com/socketio/socket.io#readme",
+  "dependencies": {
+    "joi": "^17.4.0",
+    "socket.io": "^4.0.1",
+    "uuid": "^8.3.2"
+  },
+  "devDependencies": {
+    "@types/chai": "^4.2.16",
+    "@types/mocha": "^10.0.0",
+    "@types/uuid": "^8.3.0",
+    "chai": "^4.3.4",
+    "mocha": "^10.0.0",
+    "nyc": "^15.1.0",
+    "socket.io-client": "^4.0.1",
+    "ts-node": "^10.9.1",
+    "typescript": "^4.2.4"
+  }
+}

examples/basic-crud-application/server/test/todo-management/todo.tests.ts

@@ -0,0 +1,309 @@
+import { createApplication } from "../../lib/app";
+import { createServer, Server } from "http";
+import {
+  InMemoryTodoRepository,
+  TodoRepository,
+} from "../../lib/todo-management/todo.repository";
+import { AddressInfo } from "net";
+import { io, Socket } from "socket.io-client";
+import { ClientEvents, ServerEvents } from "../../lib/events";
+import { expect } from "chai";
+
+const createPartialDone = (count: number, done: () => void) => {
+  let i = 0;
+  return () => {
+    if (++i === count) {
+      done();
+    }
+  };
+};
+
+describe("todo management", () => {
+  let httpServer: Server,
+    socket: Socket<ServerEvents, ClientEvents>,
+    otherSocket: Socket<ServerEvents, ClientEvents>,
+    todoRepository: TodoRepository;
+
+  beforeEach((done) => {
+    const partialDone = createPartialDone(2, done);
+
+    httpServer = createServer();
+    todoRepository = new InMemoryTodoRepository();
+
+    createApplication(httpServer, {
+      todoRepository,
+    });
+
+    httpServer.listen(() => {
+      const port = (httpServer.address() as AddressInfo).port;
+      socket = io(`http://localhost:${port}`);
+      socket.on("connect", partialDone);
+
+      otherSocket = io(`http://localhost:${port}`);
+      otherSocket.on("connect", partialDone);
+    });
+  });
+
+  afterEach(() => {
+    httpServer.close();
+    socket.disconnect();
+    otherSocket.disconnect();
+  });
+
+  describe("create todo", () => {
+    it("should create a todo entity", (done) => {
+      const partialDone = createPartialDone(2, done);
+
+      socket.emit(
+        "todo:create",
+        {
+          title: "lorem ipsum",
+          completed: false,
+        },
+        async (res) => {
+          if ("error" in res) {
+            return done(new Error("should not happen"));
+          }
+          expect(res.data).to.be.a("string");
+
+          const storedEntity = await todoRepository.findById(res.data);
+          expect(storedEntity).to.eql({
+            id: res.data,
+            title: "lorem ipsum",
+            completed: false,
+          });
+
+          partialDone();
+        }
+      );
+
+      otherSocket.on("todo:created", (todo) => {
+        expect(todo.id).to.be.a("string");
+        expect(todo.title).to.eql("lorem ipsum");
+        expect(todo.completed).to.eql(false);
+        partialDone();
+      });
+    });
+
+    it("should fail with an invalid entity", (done) => {
+      const incompleteTodo = {
+        completed: "false",
+        description: true,
+      };
+      // @ts-ignore
+      socket.emit("todo:create", incompleteTodo, (res) => {
+        if (!("error" in res)) {
+          return done(new Error("should not happen"));
+        }
+        expect(res.error).to.eql("invalid payload");
+        expect(res.errorDetails).to.eql([
+          {
+            message: '"title" is required',
+            path: ["title"],
+            type: "any.required",
+          },
+        ]);
+        done();
+      });
+
+      otherSocket.on("todo:created", () => {
+        done(new Error("should not happen"));
+      });
+    });
+  });
+
+  describe("read todo", () => {
+    it("should return a todo entity", (done) => {
+      todoRepository.save({
+        id: "254dbf85-f5b9-4675-b913-acab5d600884",
+        title: "lorem ipsum",
+        completed: true,
+      });
+
+      socket.emit(
+        "todo:read",
+        "254dbf85-f5b9-4675-b913-acab5d600884",
+        (res) => {
+          if ("error" in res) {
+            return done(new Error("should not happen"));
+          }
+          expect(res.data.id).to.eql("254dbf85-f5b9-4675-b913-acab5d600884");
+          expect(res.data.title).to.eql("lorem ipsum");
+          expect(res.data.completed).to.eql(true);
+          done();
+        }
+      );
+    });
+
+    it("should fail with an invalid ID", (done) => {
+      socket.emit("todo:read", "123", (res) => {
+        if ("error" in res) {
+          expect(res.error).to.eql("entity not found");
+          done();
+        } else {
+          done(new Error("should not happen"));
+        }
+      });
+    });
+
+    it("should fail with an unknown entity", (done) => {
+      socket.emit(
+        "todo:read",
+        "6edcf81e-7049-40e0-8497-9cdd52414f75",
+        (res) => {
+          if ("error" in res) {
+            expect(res.error).to.eql("entity not found");
+            done();
+          } else {
+            done(new Error("should not happen"));
+          }
+        }
+      );
+    });
+  });
+
+  describe("update todo", () => {
+    it("should update a todo entity", (done) => {
+      const partialDone = createPartialDone(2, done);
+
+      todoRepository.save({
+        id: "c7790b35-6bbb-45dd-8d67-a281ca407b43",
+        title: "lorem ipsum",
+        completed: true,
+      });
+
+      socket.emit(
+        "todo:update",
+        {
+          id: "c7790b35-6bbb-45dd-8d67-a281ca407b43",
+          title: "dolor sit amet",
+          completed: true,
+        },
+        async () => {
+          const storedEntity = await todoRepository.findById(
+            "c7790b35-6bbb-45dd-8d67-a281ca407b43"
+          );
+          expect(storedEntity).to.eql({
+            id: "c7790b35-6bbb-45dd-8d67-a281ca407b43",
+            title: "dolor sit amet",
+            completed: true,
+          });
+          partialDone();
+        }
+      );
+
+      otherSocket.on("todo:updated", (todo) => {
+        expect(todo.title).to.eql("dolor sit amet");
+        expect(todo.completed).to.eql(true);
+        partialDone();
+      });
+    });
+
+    it("should fail with an invalid entity", (done) => {
+      const incompleteTodo = {
+        id: "123",
+        completed: "false",
+        description: true,
+      };
+      // @ts-ignore
+      socket.emit("todo:update", incompleteTodo, (res) => {
+        if (!(res && "error" in res)) {
+          return done(new Error("should not happen"));
+        }
+        expect(res.error).to.eql("invalid payload");
+        expect(res.errorDetails).to.eql([
+          {
+            message: '"id" must be a valid GUID',
+            path: ["id"],
+            type: "string.guid",
+          },
+          {
+            message: '"title" is required',
+            path: ["title"],
+            type: "any.required",
+          },
+        ]);
+        done();
+      });
+
+      otherSocket.on("todo:updated", () => {
+        done(new Error("should not happen"));
+      });
+    });
+  });
+
+  describe("delete todo", () => {
+    it("should delete a todo entity", (done) => {
+      const partialDone = createPartialDone(2, done);
+      const id = "58960ab2-4e78-4ced-8079-134f12179d46";
+
+      todoRepository.save({
+        id,
+        title: "lorem ipsum",
+        completed: true,
+      });
+
+      socket.emit("todo:delete", id, async () => {
+        try {
+          await todoRepository.findById(id);
+        } catch (e) {
+          partialDone();
+        }
+      });
+
+      otherSocket.on("todo:deleted", (id) => {
+        expect(id).to.eql("58960ab2-4e78-4ced-8079-134f12179d46");
+        partialDone();
+      });
+    });
+
+    it("should fail with an invalid ID", (done) => {
+      socket.emit("todo:delete", "123", (res) => {
+        if (!(res && "error" in res)) {
+          return done(new Error("should not happen"));
+        }
+        expect(res.error).to.eql("entity not found");
+        done();
+      });
+
+      otherSocket.on("todo:deleted", () => {
+        done(new Error("should not happen"));
+      });
+    });
+  });
+
+  describe("list todo", () => {
+    it("should return a list of entities", (done) => {
+      todoRepository.save({
+        id: "d445db6d-9d55-4ff2-88ae-bd1f81c299d2",
+        title: "lorem ipsum",
+        completed: false,
+      });
+
+      todoRepository.save({
+        id: "5f56fb59-a887-4984-93bf-eb39b4170a35",
+        title: "dolor sit amet",
+        completed: true,
+      });
+
+      socket.emit("todo:list", (res) => {
+        if ("error" in res) {
+          return done(new Error("should not happen"));
+        }
+        expect(res.data).to.eql([
+          {
+            id: "d445db6d-9d55-4ff2-88ae-bd1f81c299d2",
+            title: "lorem ipsum",
+            completed: false,
+          },
+          {
+            id: "5f56fb59-a887-4984-93bf-eb39b4170a35",
+            title: "dolor sit amet",
+            completed: true,
+          },
+        ]);
+        done();
+      });
+    });
+  });
+});

examples/basic-crud-application/server/tsconfig.json

@@ -0,0 +1,11 @@
+{
+  "compilerOptions": {
+    "outDir": "./dist",
+    "module": "commonjs",
+    "target": "es2017",
+    "strict": true
+  },
+  "include": [
+    "./lib/**/*"
+  ]
+}

examples/chat/README.md

@@ -6,7 +6,7 @@ A simple chat demo for Socket.IO
 ## How to use
 
 ```
-$ npm ci
+$ npm i
 $ npm start
 ```
 

examples/chat/public/main.js

@@ -264,14 +264,14 @@ $(function() {
     log('you have been disconnected');
   });
 
-  socket.on('reconnect', () => {
+  socket.io.on('reconnect', () => {
     log('you have been reconnected');
     if (username) {
       socket.emit('add user', username);
     }
   });
 
-  socket.on('reconnect_error', () => {
+  socket.io.on('reconnect_error', () => {
     log('attempt to reconnect has failed');
   });
 

examples/cluster-nginx/docker-compose.yml

@@ -1,6 +1,8 @@
 
 nginx:
-  build: ./nginx
+  image: nginx:alpine
+  volumes:
+    - ./nginx.conf:/etc/nginx/nginx.conf:ro
   links:
     - server-john
     - server-paul

examples/cluster-nginx/nginx/Dockerfile

@@ -1,3 +0,0 @@
-
-FROM nginx:alpine
-COPY nginx.conf /etc/nginx/nginx.conf

examples/cluster-nginx/server/index.js

@@ -1,15 +1,18 @@
-// Setup basic express server
-var express = require('express');
-var app = express();
-var server = require('http').createServer(app);
-var io = require('socket.io')(server);
-var redis = require('socket.io-redis');
-var port = process.env.PORT || 3000;
-var serverName = process.env.NAME || 'Unknown';
+const express = require('express');
+const app = express();
+const server = require('http').createServer(app);
+const io = require('socket.io')(server);
+const { createAdapter } = require('@socket.io/redis-adapter');
+const { createClient } = require('redis');
+const port = process.env.PORT || 3000;
+const serverName = process.env.NAME || 'Unknown';
 
-io.adapter(redis({ host: 'redis', port: 6379 }));
+const pubClient = createClient({ host: 'redis', port: 6379 });
+const subClient = pubClient.duplicate();
 
-server.listen(port, function () {
+io.adapter(createAdapter(pubClient, subClient));
+
+server.listen(port, () => {
   console.log('Server listening at port %d', port);
   console.log('Hello, I\'m %s, how can I help?', serverName);
 });
@@ -19,15 +22,15 @@ app.use(express.static(__dirname + '/public'));
 
 // Chatroom
 
-var numUsers = 0;
+let numUsers = 0;
 
-io.on('connection', function (socket) {
+io.on('connection', socket => {
   socket.emit('my-name-is', serverName);
 
-  var addedUser = false;
+  let addedUser = false;
 
   // when the client emits 'new message', this listens and executes
-  socket.on('new message', function (data) {
+  socket.on('new message', data => {
     // we tell the client to execute 'new message'
     socket.broadcast.emit('new message', {
       username: socket.username,
@@ -36,7 +39,7 @@ io.on('connection', function (socket) {
   });
 
   // when the client emits 'add user', this listens and executes
-  socket.on('add user', function (username) {
+  socket.on('add user', username => {
     if (addedUser) return;
 
     // we store the username in the socket session for this client
@@ -54,21 +57,21 @@ io.on('connection', function (socket) {
   });
 
   // when the client emits 'typing', we broadcast it to others
-  socket.on('typing', function () {
+  socket.on('typing', () => {
     socket.broadcast.emit('typing', {
       username: socket.username
     });
   });
 
   // when the client emits 'stop typing', we broadcast it to others
-  socket.on('stop typing', function () {
+  socket.on('stop typing', () => {
     socket.broadcast.emit('stop typing', {
       username: socket.username
     });
   });
 
   // when the user disconnects.. perform this
-  socket.on('disconnect', function () {
+  socket.on('disconnect', () => {
     if (addedUser) {
       --numUsers;
 

examples/cluster-nginx/server/package.json

@@ -7,9 +7,10 @@
   "private": true,
   "license": "MIT",
   "dependencies": {
+    "@socket.io/redis-adapter": "^7.0.1",
     "express": "4.13.4",
-    "socket.io": "^4.0.0",
-    "socket.io-redis": "^6.0.1"
+    "redis": "^3.1.2",
+    "socket.io": "^4.0.0"
   },
   "scripts": {
     "start": "node index.js"

examples/create-react-app-example/src/App.js

@@ -1,4 +1,5 @@
 import React, { useState, useEffect } from 'react';
+import logo from './logo.svg';
 import './App.css';
 import io from 'socket.io-client';
 
@@ -23,7 +24,7 @@ function App() {
       socket.off('disconnect');
       socket.off('message');
     };
-  });
+  }, []);
 
   const sendMessage = () => {
     socket.emit('hello!');
@@ -32,9 +33,21 @@ function App() {
   return (
     <div className="App">
       <header className="App-header">
+        <img src={logo} className="App-logo" alt="logo" />
         <p>Connected: { '' + isConnected }</p>
         <p>Last message: { lastMessage || '-' }</p>
         <button onClick={ sendMessage }>Say hello!</button>
+        <p>
+          Edit <code>src/App.js</code> and save to reload.
+        </p>
+        <a
+          className="App-link"
+          href="https://reactjs.org"
+          target="_blank"
+          rel="noopener noreferrer"
+        >
+          Learn React
+        </a>
       </header>
     </div>
   );

examples/express-session-example/README.md

@@ -0,0 +1,16 @@
+# Example with [express-session](https://www.npmjs.com/package/express-session)
+
+This example shows how to share a session context between [Express](http://expressjs.com/) and [Socket.IO](https://socket.io/docs/v4/):
+
+![Video of the example](assets/demo.gif)
+
+Please read the related guide: https://socket.io/how-to/use-with-express-session
+
+## How to use
+
+```
+$ npm install
+$ npm start
+```
+
+And point your browser to `http://localhost:3000`. Optionally, specify a port by supplying the `PORT` env variable.

examples/express-session-example/index.html

@@ -0,0 +1,57 @@
+<!DOCTYPE html>
+<html lang="en">
+  <head>
+    <meta charset="UTF-8" />
+    <title>Example with express-session</title>
+  </head>
+  <body>
+    <button onclick="incrementWithFetch()">Increment with fetch()</button>
+    <button onclick="logout()">Logout</button>
+    <p>Count: <span id="httpCount">0</span></p>
+
+    <button onclick="incrementWithEmit()">
+      Increment with Socket.IO emit()
+    </button>
+    <p>Status: <span id="ioStatus">disconnected</span></p>
+    <p>Count: <span id="ioCount">0</span></p>
+
+    <script src="/socket.io/socket.io.js"></script>
+    <script>
+      const httpCount = document.getElementById("httpCount");
+      const ioStatus = document.getElementById("ioStatus");
+      const ioCount = document.getElementById("ioCount");
+
+      const socket = io({
+        // with WebSocket only
+        // transports: ["websocket"],
+      });
+
+      async function incrementWithFetch() {
+        const response = await fetch("/incr", {
+          method: "post",
+        });
+        httpCount.innerText = await response.text();
+      }
+
+      function logout() {
+        fetch("/logout", {
+          method: "post",
+        });
+      }
+
+      async function incrementWithEmit() {
+        socket.emit("incr", (count) => {
+          ioCount.innerText = count;
+        });
+      }
+
+      socket.on("connect", () => {
+        ioStatus.innerText = "connected";
+      });
+
+      socket.on("disconnect", () => {
+        ioStatus.innerText = "disconnected";
+      });
+    </script>
+  </body>
+</html>

examples/express-session-example/index.js

@@ -0,0 +1,91 @@
+import express from "express";
+import { createServer } from "http";
+import { Server } from "socket.io";
+import session from "express-session";
+
+const port = process.env.PORT || 3000;
+
+const app = express();
+const httpServer = createServer(app);
+
+const sessionMiddleware = session({
+  secret: "changeit",
+  resave: true,
+  saveUninitialized: true,
+});
+
+app.use(sessionMiddleware);
+
+app.get("/", (req, res) => {
+  res.sendFile("./index.html", { root: process.cwd() });
+});
+
+app.post("/incr", (req, res) => {
+  const session = req.session;
+  session.count = (session.count || 0) + 1;
+  res.status(200).end("" + session.count);
+});
+
+app.post("/logout", (req, res) => {
+  const sessionId = req.session.id;
+  req.session.destroy(() => {
+    // disconnect all Socket.IO connections linked to this session ID
+    io.to(sessionId).disconnectSockets();
+    res.status(204).end();
+  });
+});
+
+const io = new Server(httpServer, {
+  allowRequest: (req, callback) => {
+    // with HTTP long-polling, we have access to the HTTP response here, but this is not
+    // the case with WebSocket, so we provide a dummy response object
+    const fakeRes = {
+      getHeader() {
+        return [];
+      },
+      setHeader(key, values) {
+        req.cookieHolder = values[0];
+      },
+      writeHead() {},
+    };
+    sessionMiddleware(req, fakeRes, () => {
+      if (req.session) {
+        // trigger the setHeader() above
+        fakeRes.writeHead();
+        // manually save the session (normally triggered by res.end())
+        req.session.save();
+      }
+      callback(null, true);
+    });
+  },
+});
+
+io.engine.on("initial_headers", (headers, req) => {
+  if (req.cookieHolder) {
+    headers["set-cookie"] = req.cookieHolder;
+    delete req.cookieHolder;
+  }
+});
+
+io.on("connect", (socket) => {
+  const req = socket.request;
+
+  socket.join(req.session.id);
+
+  socket.on("incr", (cb) => {
+    req.session.reload((err) => {
+      if (err) {
+        // session has expired
+        return socket.disconnect();
+      }
+      req.session.count = (req.session.count || 0) + 1;
+      req.session.save(() => {
+        cb(req.session.count);
+      });
+    });
+  });
+});
+
+httpServer.listen(port, () => {
+  console.log(`application is running at: http://localhost:${port}`);
+});

examples/express-session-example/package.json

@@ -0,0 +1,15 @@
+{
+  "name": "express-session-example",
+  "version": "0.0.1",
+  "private": true,
+  "type": "module",
+  "description": "Example with express-session (https://github.com/expressjs/session)",
+  "scripts": {
+    "start": "node index.js"
+  },
+  "dependencies": {
+    "express": "~4.17.3",
+    "express-session": "~1.17.2",
+    "socket.io": "~4.4.1"
+  }
+}

examples/rollup-server-bundle/.gitignore

@@ -0,0 +1 @@
+bundle.js

examples/rollup-server-bundle/index.js

@@ -0,0 +1,3 @@
+import { Server } from "socket.io";
+
+new Server(0);

examples/rollup-server-bundle/package.json

@@ -0,0 +1,19 @@
+{
+  "name": "rollup-server-bundle",
+  "version": "0.0.1",
+  "description": "",
+  "main": "index.js",
+  "type": "module",
+  "author": "Damien Arrachequesne <damien.arrachequesne@gmail.com>",
+  "license": "ISC",
+  "scripts": {
+    "build": "rollup --config rollup.config.js"
+  },
+  "devDependencies": {
+    "@rollup/plugin-commonjs": "^21.0.3",
+    "@rollup/plugin-json": "^4.1.0",
+    "@rollup/plugin-node-resolve": "^13.1.3",
+    "rollup": "^2.70.1",
+    "socket.io": "^4.4.1"
+  }
+}

examples/rollup-server-bundle/rollup.config.js

@@ -0,0 +1,12 @@
+import resolve from "@rollup/plugin-node-resolve";
+import commonjs from "@rollup/plugin-commonjs";
+import json from "@rollup/plugin-json";
+
+export default {
+  input: "index.js",
+  output: {
+    file: "bundle.js",
+    format: "esm",
+  },
+  plugins: [resolve(), commonjs(), json({ compact: true })],
+};

examples/webpack-build-server/index.js

@@ -0,0 +1,20 @@
+const { Server } = require("socket.io");
+
+const clientFile = require("./node_modules/socket.io/client-dist/socket.io.min?raw");
+const clientMap = require("./node_modules/socket.io/client-dist/socket.io.min.js.map?raw");
+
+Server.sendFile = (filename, req, res) => {
+  res.end(filename.endsWith(".map") ? clientMap : clientFile);
+};
+
+const io = new Server();
+
+io.on("connection", socket => {
+  console.log(`connect ${socket.id}`);
+
+  socket.on("disconnect", (reason) => {
+    console.log(`disconnect ${socket.id} due to ${reason}`);
+  });
+});
+
+io.listen(3000);

examples/webpack-build-server/lib/index.js

@@ -1,15 +0,0 @@
-
-const server = require('http').createServer();
-const io = require('socket.io')(server, {
-  serveClient: false
-});
-const port = process.env.PORT || 3000;
-
-io.on('connect', onConnect);
-server.listen(port, () => console.log('server listening on port ' + port));
-
-function onConnect(socket){
-  console.log('connect ' + socket.id);
-
-  socket.on('disconnect', () => console.log('disconnect ' + socket.id));
-}

examples/webpack-build-server/package.json

@@ -4,13 +4,15 @@
   "description": "A sample Webpack build (for the server)",
   "scripts": {
     "start": "node dist/server.js",
-    "build": "webpack --config ./support/webpack.config.js"
+    "build": "webpack"
   },
   "author": "Damien Arrachequesne",
   "license": "MIT",
   "devDependencies": {
+    "bufferutil": "^4.0.3",
     "socket.io": "^4.0.0",
-    "webpack": "~4.43.0",
-    "webpack-cli": "~3.3.11"
+    "utf-8-validate": "^5.0.5",
+    "webpack": "^5.39.0",
+    "webpack-cli": "^4.7.2"
   }
 }

examples/webpack-build-server/support/webpack.config.js

@@ -1,10 +0,0 @@
-
-module.exports = {
-  entry: './lib/index.js',
-  target: 'node',
-  output: {
-    path: require('path').join(__dirname, '../dist'),
-    filename: 'server.js'
-  },
-  mode: 'production'
-};

examples/webpack-build-server/webpack.config.js

@@ -0,0 +1,19 @@
+const path = require("path");
+
+module.exports = {
+  entry: "./index.js",
+  target: "node",
+  mode: "production",
+  output: {
+    path: path.resolve(__dirname, "dist"),
+    filename: "index.js",
+  },
+  module: {
+    rules: [
+      {
+        resourceQuery: /raw/,
+        type: "asset/source",
+      },
+    ],
+  },
+};

examples/webpack-build/README.md

@@ -7,14 +7,5 @@ A sample Webpack build for the browser.
 
 ```
 $ npm i
-$ npm run build-all
+$ npm run build
 ```
-
-There are two WebPack configuration:
-
-- the minimal configuration, just bundling the application and its dependencies. The `app.js` file in the `dist` folder is the result of that build.
-
-- a slimmer one, where:
-  - the JSON polyfill needed for IE6/IE7 support has been removed.
-  - the `debug` calls and import have been removed (the [debug](https://github.com/visionmedia/debug) library is included in the build by default).
-  - the source has been uglified (dropping IE8 support), and an associated SourceMap has been generated.

examples/webpack-build/index.html

@@ -6,8 +6,7 @@
 </head>
 <body>
 
-  <!-- <script src="dist/app.js"></script> -->
-  <script src="dist/app.slim.js"></script>
+  <script src="dist/bundle.js"></script>
 
 </body>
-</html>
+</html>

examples/webpack-build/index.js

@@ -0,0 +1,15 @@
+import { io } from "socket.io-client";
+
+const socket = io("http://localhost:3000");
+
+socket.on("connect", () => {
+  console.log(`connect ${socket.id}`);
+});
+
+socket.on("connect_error", (err) => {
+  console.log(`connect_error due to ${err.message}`);
+});
+
+socket.on("disconnect", (reason) => {
+  console.log(`disconnect due to ${reason}`);
+});

examples/webpack-build/lib/index.js

@@ -1,12 +0,0 @@
-
-import io from 'socket.io-client';
-
-const socket = io('http://localhost:3000');
-
-console.log('init');
-
-socket.on('connect', onConnect);
-
-function onConnect(){
-  console.log('connect ' + socket.id);
-}

examples/webpack-build/package.json

@@ -2,20 +2,15 @@
   "name": "webpack-build",
   "version": "1.0.0",
   "description": "A sample Webpack build",
+  "type": "module",
   "scripts": {
-    "build": "webpack --config ./support/webpack.config.js",
-    "build-slim": "webpack --config ./support/webpack.config.slim.js",
-    "build-json-parser": "webpack --config ./support/webpack.config.json-parser.js",
-    "build-all": "npm run build && npm run build-slim && npm run build-json-parser"
+    "build": "webpack"
   },
   "author": "Damien Arrachequesne",
   "license": "MIT",
   "dependencies": {
-    "socket.io-client": "^2.0.2",
-    "socket.io-json-parser": "^2.1.0"
-  },
-  "devDependencies": {
-    "strip-loader": "^0.1.2",
-    "webpack": "^2.6.1"
+    "socket.io-client": "^4.4.1",
+    "webpack": "^5.72.0",
+    "webpack-cli": "^4.9.2"
   }
 }

examples/webpack-build/support/noop.js

@@ -1,2 +0,0 @@
-
-module.exports = function () { return function () {}; };

examples/webpack-build/support/webpack.config.js

@@ -1,8 +0,0 @@
-
-module.exports = {
-  entry: './lib/index.js',
-  output: {
-    path: require('path').join(__dirname, '../dist'),
-    filename: 'app.js'
-  }
-};

examples/webpack-build/support/webpack.config.json-parser.js

@@ -1,33 +0,0 @@
-
-var webpack = require('webpack');
-
-module.exports = {
-  entry: './lib/index.js',
-  output: {
-    path: require('path').join(__dirname, '../dist'),
-    filename: 'app.json-parser.js'
-  },
-  // generate sourcemap
-  devtool: 'source-map',
-  plugins: [
-    // replace require('debug')() with an noop function
-    new webpack.NormalModuleReplacementPlugin(/debug/, process.cwd() + '/support/noop.js'),
-    // replace socket.io-parser with socket.io-json-parser
-    new webpack.NormalModuleReplacementPlugin(/socket\.io-parser/, 'socket.io-json-parser'),
-    // use uglifyJS (IE9+ support)
-    new webpack.optimize.UglifyJsPlugin({
-      compress: {
-        warnings: false
-      }
-    })
-  ],
-  module: {
-    loaders: [
-      {
-        // strip `debug()` calls
-        test: /\.js$/,
-        loader: 'strip-loader?strip[]=debug'
-      }
-    ]
-  }
-};

examples/webpack-build/support/webpack.config.slim.js

@@ -1,31 +0,0 @@
-
-var webpack = require('webpack');
-
-module.exports = {
-  entry: './lib/index.js',
-  output: {
-    path: require('path').join(__dirname, '../dist'),
-    filename: 'app.slim.js'
-  },
-  // generate sourcemap
-  devtool: 'source-map',
-  plugins: [
-    // replace require('debug')() with an noop function
-    new webpack.NormalModuleReplacementPlugin(/debug/, process.cwd() + '/support/noop.js'),
-    // use uglifyJS (IE9+ support)
-    new webpack.optimize.UglifyJsPlugin({
-      compress: {
-        warnings: false
-      }
-    })
-  ],
-  module: {
-    loaders: [
-      {
-        // strip `debug()` calls
-        test: /\.js$/,
-        loader: 'strip-loader?strip[]=debug'
-      }
-    ]
-  }
-};

examples/webpack-build/webpack.config.js

@@ -0,0 +1,7 @@
+export default {
+  entry: "./index.js",
+  mode: "production",
+  output: {
+    filename: "bundle.js",
+  },
+};

lib/broadcast-operator.ts

@@ -7,32 +7,49 @@ import type {
   EventNames,
   EventsMap,
   TypedEventBroadcaster,
+  DecorateAcknowledgements,
+  DecorateAcknowledgementsWithTimeoutAndMultipleResponses,
+  AllButLast,
+  Last,
+  SecondArg,
 } from "./typed-events";
 
-export class BroadcastOperator<EmitEvents extends EventsMap>
-  implements TypedEventBroadcaster<EmitEvents> {
+export class BroadcastOperator<EmitEvents extends EventsMap, SocketData>
+  implements TypedEventBroadcaster<EmitEvents>
+{
   constructor(
     private readonly adapter: Adapter,
     private readonly rooms: Set<Room> = new Set<Room>(),
     private readonly exceptRooms: Set<Room> = new Set<Room>(),
-    private readonly flags: BroadcastFlags = {}
+    private readonly flags: BroadcastFlags & {
+      expectSingleResponse?: boolean;
+    } = {}
   ) {}
 
   /**
    * Targets a room when emitting.
    *
-   * @param room
-   * @return a new BroadcastOperator instance
-   * @public
+   * @example
+   * // the “foo” event will be broadcast to all connected clients in the “room-101” room
+   * io.to("room-101").emit("foo", "bar");
+   *
+   * // with an array of rooms (a client will be notified at most once)
+   * io.to(["room-101", "room-102"]).emit("foo", "bar");
+   *
+   * // with multiple chained calls
+   * io.to("room-101").to("room-102").emit("foo", "bar");
+   *
+   * @param room - a room, or an array of rooms
+   * @return a new {@link BroadcastOperator} instance for chaining
    */
-  public to(room: Room | Room[]): BroadcastOperator<EmitEvents> {
+  public to(room: Room | Room[]) {
     const rooms = new Set(this.rooms);
     if (Array.isArray(room)) {
       room.forEach((r) => rooms.add(r));
     } else {
       rooms.add(room);
     }
-    return new BroadcastOperator(
+    return new BroadcastOperator<EmitEvents, SocketData>(
       this.adapter,
       rooms,
       this.exceptRooms,
@@ -41,31 +58,43 @@ export class BroadcastOperator<EmitEvents extends EventsMap>
   }
 
   /**
-   * Targets a room when emitting.
+   * Targets a room when emitting. Similar to `to()`, but might feel clearer in some cases:
    *
-   * @param room
-   * @return a new BroadcastOperator instance
-   * @public
+   * @example
+   * // disconnect all clients in the "room-101" room
+   * io.in("room-101").disconnectSockets();
+   *
+   * @param room - a room, or an array of rooms
+   * @return a new {@link BroadcastOperator} instance for chaining
    */
-  public in(room: Room | Room[]): BroadcastOperator<EmitEvents> {
+  public in(room: Room | Room[]) {
     return this.to(room);
   }
 
   /**
    * Excludes a room when emitting.
    *
-   * @param room
-   * @return a new BroadcastOperator instance
-   * @public
+   * @example
+   * // the "foo" event will be broadcast to all connected clients, except the ones that are in the "room-101" room
+   * io.except("room-101").emit("foo", "bar");
+   *
+   * // with an array of rooms
+   * io.except(["room-101", "room-102"]).emit("foo", "bar");
+   *
+   * // with multiple chained calls
+   * io.except("room-101").except("room-102").emit("foo", "bar");
+   *
+   * @param room - a room, or an array of rooms
+   * @return a new {@link BroadcastOperator} instance for chaining
    */
-  public except(room: Room | Room[]): BroadcastOperator<EmitEvents> {
+  public except(room: Room | Room[]) {
     const exceptRooms = new Set(this.exceptRooms);
     if (Array.isArray(room)) {
       room.forEach((r) => exceptRooms.add(r));
     } else {
       exceptRooms.add(room);
     }
-    return new BroadcastOperator(
+    return new BroadcastOperator<EmitEvents, SocketData>(
       this.adapter,
       this.rooms,
       exceptRooms,
@@ -76,13 +105,15 @@ export class BroadcastOperator<EmitEvents extends EventsMap>
   /**
    * Sets the compress flag.
    *
+   * @example
+   * io.compress(false).emit("hello");
+   *
    * @param compress - if `true`, compresses the sending data
    * @return a new BroadcastOperator instance
-   * @public
    */
-  public compress(compress: boolean): BroadcastOperator<EmitEvents> {
+  public compress(compress: boolean) {
     const flags = Object.assign({}, this.flags, { compress });
-    return new BroadcastOperator(
+    return new BroadcastOperator<EmitEvents, SocketData>(
       this.adapter,
       this.rooms,
       this.exceptRooms,
@@ -95,12 +126,14 @@ export class BroadcastOperator<EmitEvents extends EventsMap>
    * receive messages (because of network slowness or other issues, or because they’re connected through long polling
    * and is in the middle of a request-response cycle).
    *
+   * @example
+   * io.volatile.emit("hello"); // the clients may or may not receive it
+   *
    * @return a new BroadcastOperator instance
-   * @public
    */
-  public get volatile(): BroadcastOperator<EmitEvents> {
+  public get volatile() {
     const flags = Object.assign({}, this.flags, { volatile: true });
-    return new BroadcastOperator(
+    return new BroadcastOperator<EmitEvents, SocketData>(
       this.adapter,
       this.rooms,
       this.exceptRooms,
@@ -111,12 +144,15 @@ export class BroadcastOperator<EmitEvents extends EventsMap>
   /**
    * Sets a modifier for a subsequent event emission that the event data will only be broadcast to the current node.
    *
-   * @return a new BroadcastOperator instance
-   * @public
+   * @example
+   * // the “foo” event will be broadcast to all connected clients on this node
+   * io.local.emit("foo", "bar");
+   *
+   * @return a new {@link BroadcastOperator} instance for chaining
    */
-  public get local(): BroadcastOperator<EmitEvents> {
+  public get local() {
     const flags = Object.assign({}, this.flags, { local: true });
-    return new BroadcastOperator(
+    return new BroadcastOperator<EmitEvents, SocketData>(
       this.adapter,
       this.rooms,
       this.exceptRooms,
@@ -124,18 +160,55 @@ export class BroadcastOperator<EmitEvents extends EventsMap>
     );
   }
 
+  /**
+   * Adds a timeout in milliseconds for the next operation
+   *
+   * @example
+   * io.timeout(1000).emit("some-event", (err, responses) => {
+   *   if (err) {
+   *     // some clients did not acknowledge the event in the given delay
+   *   } else {
+   *     console.log(responses); // one response per client
+   *   }
+   * });
+   *
+   * @param timeout
+   */
+  public timeout(timeout: number) {
+    const flags = Object.assign({}, this.flags, { timeout });
+    return new BroadcastOperator<
+      DecorateAcknowledgementsWithTimeoutAndMultipleResponses<EmitEvents>,
+      SocketData
+    >(this.adapter, this.rooms, this.exceptRooms, flags);
+  }
+
   /**
    * Emits to all clients.
    *
+   * @example
+   * // the “foo” event will be broadcast to all connected clients
+   * io.emit("foo", "bar");
+   *
+   * // the “foo” event will be broadcast to all connected clients in the “room-101” room
+   * io.to("room-101").emit("foo", "bar");
+   *
+   * // with an acknowledgement expected from all connected clients
+   * io.timeout(1000).emit("some-event", (err, responses) => {
+   *   if (err) {
+   *     // some clients did not acknowledge the event in the given delay
+   *   } else {
+   *     console.log(responses); // one response per client
+   *   }
+   * });
+   *
    * @return Always true
-   * @public
    */
   public emit<Ev extends EventNames<EmitEvents>>(
     ev: Ev,
     ...args: EventParams<EmitEvents, Ev>
   ): boolean {
     if (RESERVED_EVENTS.has(ev)) {
-      throw new Error(`"${ev}" is a reserved event name`);
+      throw new Error(`"${String(ev)}" is a reserved event name`);
     }
     // set up packet object
     const data = [ev, ...args];
@@ -144,23 +217,111 @@ export class BroadcastOperator<EmitEvents extends EventsMap>
       data: data,
     };
 
-    if ("function" == typeof data[data.length - 1]) {
-      throw new Error("Callbacks are not supported when broadcasting");
+    const withAck = typeof data[data.length - 1] === "function";
+
+    if (!withAck) {
+      this.adapter.broadcast(packet, {
+        rooms: this.rooms,
+        except: this.exceptRooms,
+        flags: this.flags,
+      });
+
+      return true;
     }
 
-    this.adapter.broadcast(packet, {
-      rooms: this.rooms,
-      except: this.exceptRooms,
-      flags: this.flags,
+    const ack = data.pop() as (...args: any[]) => void;
+    let timedOut = false;
+    let responses: any[] = [];
+
+    const timer = setTimeout(() => {
+      timedOut = true;
+      ack.apply(this, [
+        new Error("operation has timed out"),
+        this.flags.expectSingleResponse ? null : responses,
+      ]);
+    }, this.flags.timeout);
+
+    let expectedServerCount = -1;
+    let actualServerCount = 0;
+    let expectedClientCount = 0;
+
+    const checkCompleteness = () => {
+      if (
+        !timedOut &&
+        expectedServerCount === actualServerCount &&
+        responses.length === expectedClientCount
+      ) {
+        clearTimeout(timer);
+        ack.apply(this, [
+          null,
+          this.flags.expectSingleResponse ? null : responses,
+        ]);
+      }
+    };
+
+    this.adapter.broadcastWithAck(
+      packet,
+      {
+        rooms: this.rooms,
+        except: this.exceptRooms,
+        flags: this.flags,
+      },
+      (clientCount) => {
+        // each Socket.IO server in the cluster sends the number of clients that were notified
+        expectedClientCount += clientCount;
+        actualServerCount++;
+        checkCompleteness();
+      },
+      (clientResponse) => {
+        // each client sends an acknowledgement
+        responses.push(clientResponse);
+        checkCompleteness();
+      }
+    );
+
+    this.adapter.serverCount().then((serverCount) => {
+      expectedServerCount = serverCount;
+      checkCompleteness();
     });
 
     return true;
   }
 
+  /**
+   * Emits an event and waits for an acknowledgement from all clients.
+   *
+   * @example
+   * try {
+   *   const responses = await io.timeout(1000).emitWithAck("some-event");
+   *   console.log(responses); // one response per client
+   * } catch (e) {
+   *   // some clients did not acknowledge the event in the given delay
+   * }
+   *
+   * @return a Promise that will be fulfilled when all clients have acknowledged the event
+   */
+  public emitWithAck<Ev extends EventNames<EmitEvents>>(
+    ev: Ev,
+    ...args: AllButLast<EventParams<EmitEvents, Ev>>
+  ): Promise<SecondArg<Last<EventParams<EmitEvents, Ev>>>> {
+    return new Promise((resolve, reject) => {
+      args.push((err, responses) => {
+        if (err) {
+          err.responses = responses;
+          return reject(err);
+        } else {
+          return resolve(responses);
+        }
+      });
+      this.emit(ev, ...(args as any[] as EventParams<EmitEvents, Ev>));
+    });
+  }
+
   /**
    * Gets a list of clients.
    *
-   * @public
+   * @deprecated this method will be removed in the next major release, please use {@link Server#serverSideEmit} or
+   * {@link fetchSockets} instead.
    */
   public allSockets(): Promise<Set<SocketId>> {
     if (!this.adapter) {
@@ -172,71 +333,122 @@ export class BroadcastOperator<EmitEvents extends EventsMap>
   }
 
   /**
-   * Returns the matching socket instances
+   * Returns the matching socket instances. This method works across a cluster of several Socket.IO servers.
    *
-   * @public
+   * Note: this method also works within a cluster of multiple Socket.IO servers, with a compatible {@link Adapter}.
+   *
+   * @example
+   * // return all Socket instances
+   * const sockets = await io.fetchSockets();
+   *
+   * // return all Socket instances in the "room1" room
+   * const sockets = await io.in("room1").fetchSockets();
+   *
+   * for (const socket of sockets) {
+   *   console.log(socket.id);
+   *   console.log(socket.handshake);
+   *   console.log(socket.rooms);
+   *   console.log(socket.data);
+   *
+   *   socket.emit("hello");
+   *   socket.join("room1");
+   *   socket.leave("room2");
+   *   socket.disconnect();
+   * }
    */
-  public fetchSockets(): Promise<RemoteSocket<EmitEvents>[]> {
+  public fetchSockets(): Promise<RemoteSocket<EmitEvents, SocketData>[]> {
     return this.adapter
       .fetchSockets({
         rooms: this.rooms,
         except: this.exceptRooms,
+        flags: this.flags,
       })
       .then((sockets) => {
         return sockets.map((socket) => {
           if (socket instanceof Socket) {
             // FIXME the TypeScript compiler complains about missing private properties
-            return (socket as unknown) as RemoteSocket<EmitEvents>;
+            return socket as unknown as RemoteSocket<EmitEvents, SocketData>;
           } else {
-            return new RemoteSocket(this.adapter, socket as SocketDetails);
+            return new RemoteSocket(
+              this.adapter,
+              socket as SocketDetails<SocketData>
+            );
           }
         });
       });
   }
 
   /**
-   * Makes the matching socket instances join the specified rooms
+   * Makes the matching socket instances join the specified rooms.
    *
-   * @param room
-   * @public
+   * Note: this method also works within a cluster of multiple Socket.IO servers, with a compatible {@link Adapter}.
+   *
+   * @example
+   *
+   * // make all socket instances join the "room1" room
+   * io.socketsJoin("room1");
+   *
+   * // make all socket instances in the "room1" room join the "room2" and "room3" rooms
+   * io.in("room1").socketsJoin(["room2", "room3"]);
+   *
+   * @param room - a room, or an array of rooms
    */
   public socketsJoin(room: Room | Room[]): void {
     this.adapter.addSockets(
       {
         rooms: this.rooms,
         except: this.exceptRooms,
+        flags: this.flags,
       },
       Array.isArray(room) ? room : [room]
     );
   }
 
   /**
-   * Makes the matching socket instances leave the specified rooms
+   * Makes the matching socket instances leave the specified rooms.
    *
-   * @param room
-   * @public
+   * Note: this method also works within a cluster of multiple Socket.IO servers, with a compatible {@link Adapter}.
+   *
+   * @example
+   * // make all socket instances leave the "room1" room
+   * io.socketsLeave("room1");
+   *
+   * // make all socket instances in the "room1" room leave the "room2" and "room3" rooms
+   * io.in("room1").socketsLeave(["room2", "room3"]);
+   *
+   * @param room - a room, or an array of rooms
    */
   public socketsLeave(room: Room | Room[]): void {
     this.adapter.delSockets(
       {
         rooms: this.rooms,
         except: this.exceptRooms,
+        flags: this.flags,
       },
       Array.isArray(room) ? room : [room]
     );
   }
 
   /**
-   * Makes the matching socket instances disconnect
+   * Makes the matching socket instances disconnect.
+   *
+   * Note: this method also works within a cluster of multiple Socket.IO servers, with a compatible {@link Adapter}.
+   *
+   * @example
+   * // make all socket instances disconnect (the connections might be kept alive for other namespaces)
+   * io.disconnectSockets();
+   *
+   * // make all socket instances in the "room1" room disconnect and close the underlying connections
+   * io.in("room1").disconnectSockets(true);
    *
    * @param close - whether to close the underlying connection
-   * @public
    */
   public disconnectSockets(close: boolean = false): void {
     this.adapter.disconnectSockets(
       {
         rooms: this.rooms,
         except: this.exceptRooms,
+        flags: this.flags,
       },
       close
     );
@@ -246,31 +458,69 @@ export class BroadcastOperator<EmitEvents extends EventsMap>
 /**
  * Format of the data when the Socket instance exists on another Socket.IO server
  */
-interface SocketDetails {
+interface SocketDetails<SocketData> {
   id: SocketId;
   handshake: Handshake;
   rooms: Room[];
-  data: any;
+  data: SocketData;
 }
 
 /**
  * Expose of subset of the attributes and methods of the Socket class
  */
-export class RemoteSocket<EmitEvents extends EventsMap>
-  implements TypedEventBroadcaster<EmitEvents> {
+export class RemoteSocket<EmitEvents extends EventsMap, SocketData>
+  implements TypedEventBroadcaster<EmitEvents>
+{
   public readonly id: SocketId;
   public readonly handshake: Handshake;
   public readonly rooms: Set<Room>;
-  public readonly data: any;
+  public readonly data: SocketData;
 
-  private readonly operator: BroadcastOperator<EmitEvents>;
+  private readonly operator: BroadcastOperator<EmitEvents, SocketData>;
 
-  constructor(adapter: Adapter, details: SocketDetails) {
+  constructor(adapter: Adapter, details: SocketDetails<SocketData>) {
     this.id = details.id;
     this.handshake = details.handshake;
     this.rooms = new Set(details.rooms);
     this.data = details.data;
-    this.operator = new BroadcastOperator(adapter, new Set([this.id]));
+    this.operator = new BroadcastOperator<EmitEvents, SocketData>(
+      adapter,
+      new Set([this.id]),
+      new Set(),
+      {
+        expectSingleResponse: true, // so that remoteSocket.emit() with acknowledgement behaves like socket.emit()
+      }
+    );
+  }
+
+  /**
+   * Adds a timeout in milliseconds for the next operation.
+   *
+   * @example
+   * const sockets = await io.fetchSockets();
+   *
+   * for (const socket of sockets) {
+   *   if (someCondition) {
+   *     socket.timeout(1000).emit("some-event", (err) => {
+   *       if (err) {
+   *         // the client did not acknowledge the event in the given delay
+   *       }
+   *     });
+   *   }
+   * }
+   *
+   * // note: if possible, using a room instead of looping over all sockets is preferable
+   * io.timeout(1000).to(someConditionRoom).emit("some-event", (err, responses) => {
+   *   // ...
+   * });
+   *
+   * @param timeout
+   */
+  public timeout(timeout: number) {
+    return this.operator.timeout(timeout) as BroadcastOperator<
+      DecorateAcknowledgements<EmitEvents>,
+      SocketData
+    >;
   }
 
   public emit<Ev extends EventNames<EmitEvents>>(
@@ -284,7 +534,6 @@ export class RemoteSocket<EmitEvents extends EventsMap>
    * Joins a room.
    *
    * @param {String|Array} room - room or array of rooms
-   * @public
    */
   public join(room: Room | Room[]): void {
     return this.operator.socketsJoin(room);
@@ -294,7 +543,6 @@ export class RemoteSocket<EmitEvents extends EventsMap>
    * Leaves a room.
    *
    * @param {String} room
-   * @public
    */
   public leave(room: Room): void {
     return this.operator.socketsLeave(room);
@@ -305,8 +553,6 @@ export class RemoteSocket<EmitEvents extends EventsMap>
    *
    * @param {Boolean} close - if `true`, closes the underlying connection
    * @return {Socket} self
-   *
-   * @public
    */
   public disconnect(close = false): this {
     this.operator.disconnectSockets(close);

lib/client.ts

@@ -2,25 +2,54 @@ import { Decoder, Encoder, Packet, PacketType } from "socket.io-parser";
 import debugModule = require("debug");
 import url = require("url");
 import type { IncomingMessage } from "http";
-import type { Namespace, Server } from "./index";
+import type { Server } from "./index";
+import type { Namespace } from "./namespace";
 import type { EventsMap } from "./typed-events";
 import type { Socket } from "./socket";
 import type { SocketId } from "socket.io-adapter";
+import type { Socket as RawSocket } from "engine.io";
 
 const debug = debugModule("socket.io:client");
 
+interface WriteOptions {
+  compress?: boolean;
+  volatile?: boolean;
+  preEncoded?: boolean;
+  wsPreEncoded?: string;
+}
+
+type CloseReason =
+  | "transport error"
+  | "transport close"
+  | "forced close"
+  | "ping timeout"
+  | "parse error";
+
 export class Client<
   ListenEvents extends EventsMap,
-  EmitEvents extends EventsMap
+  EmitEvents extends EventsMap,
+  ServerSideEvents extends EventsMap,
+  SocketData = any
 > {
-  public readonly conn;
+  public readonly conn: RawSocket;
 
   private readonly id: string;
-  private readonly server: Server<ListenEvents, EmitEvents>;
+  private readonly server: Server<
+    ListenEvents,
+    EmitEvents,
+    ServerSideEvents,
+    SocketData
+  >;
   private readonly encoder: Encoder;
   private readonly decoder: Decoder;
-  private sockets: Map<SocketId, Socket<ListenEvents, EmitEvents>> = new Map();
-  private nsps: Map<string, Socket<ListenEvents, EmitEvents>> = new Map();
+  private sockets: Map<
+    SocketId,
+    Socket<ListenEvents, EmitEvents, ServerSideEvents, SocketData>
+  > = new Map();
+  private nsps: Map<
+    string,
+    Socket<ListenEvents, EmitEvents, ServerSideEvents, SocketData>
+  > = new Map();
   private connectTimeout?: NodeJS.Timeout;
 
   /**
@@ -30,7 +59,10 @@ export class Client<
    * @param conn
    * @package
    */
-  constructor(server: Server<ListenEvents, EmitEvents>, conn: any) {
+  constructor(
+    server: Server<ListenEvents, EmitEvents, ServerSideEvents, SocketData>,
+    conn: any
+  ) {
     this.server = server;
     this.conn = conn;
     this.encoder = server.encoder;
@@ -82,7 +114,7 @@ export class Client<
    * @param {Object} auth - the auth parameters
    * @private
    */
-  private connect(name: string, auth: object = {}): void {
+  private connect(name: string, auth: Record<string, unknown> = {}): void {
     if (this.server._nsps.has(name)) {
       debug("connecting to namespace %s", name);
       return this.doConnect(name, auth);
@@ -91,9 +123,12 @@ export class Client<
     this.server._checkNamespace(
       name,
       auth,
-      (dynamicNspName: Namespace<ListenEvents, EmitEvents> | false) => {
+      (
+        dynamicNspName:
+          | Namespace<ListenEvents, EmitEvents, ServerSideEvents, SocketData>
+          | false
+      ) => {
         if (dynamicNspName) {
-          debug("dynamic namespace %s was created", dynamicNspName);
           this.doConnect(name, auth);
         } else {
           debug("creation of namespace %s was denied", name);
@@ -117,10 +152,10 @@ export class Client<
    *
    * @private
    */
-  private doConnect(name: string, auth: object): void {
+  private doConnect(name: string, auth: Record<string, unknown>): void {
     const nsp = this.server.of(name);
 
-    const socket = nsp._add(this, auth, () => {
+    nsp._add(this, auth, (socket) => {
       this.sockets.set(socket.id, socket);
       this.nsps.set(nsp.name, socket);
 
@@ -149,7 +184,9 @@ export class Client<
    *
    * @private
    */
-  _remove(socket: Socket<ListenEvents, EmitEvents>): void {
+  _remove(
+    socket: Socket<ListenEvents, EmitEvents, ServerSideEvents, SocketData>
+  ): void {
     if (this.sockets.has(socket.id)) {
       const nsp = this.sockets.get(socket.id)!.nsp.name;
       this.sockets.delete(socket.id);
@@ -179,30 +216,32 @@ export class Client<
    * @param {Object} opts
    * @private
    */
-  _packet(packet: Packet, opts?: any): void {
-    opts = opts || {};
-    const self = this;
-
-    // this writes to the actual connection
-    function writeToEngine(encodedPackets: any) {
-      // TODO clarify this.
-      if (opts.volatile && !self.conn.transport.writable) return;
-      for (let i = 0; i < encodedPackets.length; i++) {
-        self.conn.write(encodedPackets[i], { compress: opts.compress });
-      }
-    }
-
-    if ("open" === this.conn.readyState) {
-      debug("writing packet %j", packet);
-      if (!opts.preEncoded) {
-        // not broadcasting, need to encode
-        writeToEngine(this.encoder.encode(packet)); // encode, then write results to engine
-      } else {
-        // a broadcast pre-encodes a packet
-        writeToEngine(packet);
-      }
-    } else {
+  _packet(packet: Packet | any[], opts: WriteOptions = {}): void {
+    if (this.conn.readyState !== "open") {
       debug("ignoring packet write %j", packet);
+      return;
+    }
+    const encodedPackets = opts.preEncoded
+      ? (packet as any[]) // previous versions of the adapter incorrectly used socket.packet() instead of writeToEngine()
+      : this.encoder.encode(packet as Packet);
+    this.writeToEngine(encodedPackets, opts);
+  }
+
+  private writeToEngine(
+    encodedPackets: Array<string | Buffer>,
+    opts: WriteOptions
+  ): void {
+    if (opts.volatile && !this.conn.transport.writable) {
+      debug(
+        "volatile packet is discarded since the transport is not currently writable"
+      );
+      return;
+    }
+    const packets = Array.isArray(encodedPackets)
+      ? encodedPackets
+      : [encodedPackets];
+    for (const encodedPacket of packets) {
+      this.conn.write(encodedPacket, opts);
     }
   }
 
@@ -216,6 +255,7 @@ export class Client<
     try {
       this.decoder.add(data);
     } catch (e) {
+      debug("invalid packet format");
       this.onerror(e);
     }
   }
@@ -226,22 +266,31 @@ export class Client<
    * @private
    */
   private ondecoded(packet: Packet): void {
-    if (PacketType.CONNECT === packet.type) {
-      if (this.conn.protocol === 3) {
-        const parsed = url.parse(packet.nsp, true);
-        this.connect(parsed.pathname!, parsed.query);
-      } else {
-        this.connect(packet.nsp, packet.data);
-      }
+    let namespace: string;
+    let authPayload: Record<string, unknown>;
+    if (this.conn.protocol === 3) {
+      const parsed = url.parse(packet.nsp, true);
+      namespace = parsed.pathname!;
+      authPayload = parsed.query;
     } else {
-      const socket = this.nsps.get(packet.nsp);
-      if (socket) {
-        process.nextTick(function () {
-          socket._onpacket(packet);
-        });
-      } else {
-        debug("no socket for namespace %s", packet.nsp);
-      }
+      namespace = packet.nsp;
+      authPayload = packet.data;
+    }
+    const socket = this.nsps.get(namespace);
+
+    if (!socket && packet.type === PacketType.CONNECT) {
+      this.connect(namespace, authPayload);
+    } else if (
+      socket &&
+      packet.type !== PacketType.CONNECT &&
+      packet.type !== PacketType.CONNECT_ERROR
+    ) {
+      process.nextTick(function () {
+        socket._onpacket(packet);
+      });
+    } else {
+      debug("invalid state (packet type: %s)", packet.type);
+      this.close();
     }
   }
 
@@ -262,9 +311,13 @@ export class Client<
    * Called upon transport close.
    *
    * @param reason
+   * @param description
    * @private
    */
-  private onclose(reason: string): void {
+  private onclose(
+    reason: CloseReason | "forced server close",
+    description?: any
+  ): void {
     debug("client close with reason %s", reason);
 
     // ignore a potential subsequent `close` event
@@ -272,7 +325,7 @@ export class Client<
 
     // `nsps` and `sockets` are cleaned up seamlessly
     for (const socket of this.sockets.values()) {
-      socket._onclose(reason);
+      socket._onclose(reason, description);
     }
     this.sockets.clear();
 

lib/namespace.ts

@@ -6,11 +6,16 @@ import {
   EventsMap,
   StrictEventEmitter,
   DefaultEventsMap,
+  DecorateAcknowledgementsWithTimeoutAndMultipleResponses,
+  AllButLast,
+  Last,
+  FirstArg,
+  SecondArg,
 } from "./typed-events";
 import type { Client } from "./client";
 import debugModule from "debug";
 import type { Adapter, Room, SocketId } from "socket.io-adapter";
-import { BroadcastOperator, RemoteSocket } from "./broadcast-operator";
+import { BroadcastOperator } from "./broadcast-operator";
 
 const debug = debugModule("socket.io:namespace");
 
@@ -20,35 +25,126 @@ export interface ExtendedError extends Error {
 
 export interface NamespaceReservedEventsMap<
   ListenEvents extends EventsMap,
-  EmitEvents extends EventsMap
+  EmitEvents extends EventsMap,
+  ServerSideEvents extends EventsMap,
+  SocketData
 > {
-  connect: (socket: Socket<ListenEvents, EmitEvents>) => void;
-  connection: (socket: Socket<ListenEvents, EmitEvents>) => void;
+  connect: (
+    socket: Socket<ListenEvents, EmitEvents, ServerSideEvents, SocketData>
+  ) => void;
+  connection: (
+    socket: Socket<ListenEvents, EmitEvents, ServerSideEvents, SocketData>
+  ) => void;
 }
 
+export interface ServerReservedEventsMap<
+  ListenEvents extends EventsMap,
+  EmitEvents extends EventsMap,
+  ServerSideEvents extends EventsMap,
+  SocketData
+> extends NamespaceReservedEventsMap<
+    ListenEvents,
+    EmitEvents,
+    ServerSideEvents,
+    SocketData
+  > {
+  new_namespace: (
+    namespace: Namespace<ListenEvents, EmitEvents, ServerSideEvents, SocketData>
+  ) => void;
+}
+
+export const RESERVED_EVENTS: ReadonlySet<string | Symbol> = new Set<
+  keyof ServerReservedEventsMap<never, never, never, never>
+>(<const>["connect", "connection", "new_namespace"]);
+
+/**
+ * A Namespace is a communication channel that allows you to split the logic of your application over a single shared
+ * connection.
+ *
+ * Each namespace has its own:
+ *
+ * - event handlers
+ *
+ * ```
+ * io.of("/orders").on("connection", (socket) => {
+ *   socket.on("order:list", () => {});
+ *   socket.on("order:create", () => {});
+ * });
+ *
+ * io.of("/users").on("connection", (socket) => {
+ *   socket.on("user:list", () => {});
+ * });
+ * ```
+ *
+ * - rooms
+ *
+ * ```
+ * const orderNamespace = io.of("/orders");
+ *
+ * orderNamespace.on("connection", (socket) => {
+ *   socket.join("room1");
+ *   orderNamespace.to("room1").emit("hello");
+ * });
+ *
+ * const userNamespace = io.of("/users");
+ *
+ * userNamespace.on("connection", (socket) => {
+ *   socket.join("room1"); // distinct from the room in the "orders" namespace
+ *   userNamespace.to("room1").emit("holà");
+ * });
+ * ```
+ *
+ * - middlewares
+ *
+ * ```
+ * const orderNamespace = io.of("/orders");
+ *
+ * orderNamespace.use((socket, next) => {
+ *   // ensure the socket has access to the "orders" namespace
+ * });
+ *
+ * const userNamespace = io.of("/users");
+ *
+ * userNamespace.use((socket, next) => {
+ *   // ensure the socket has access to the "users" namespace
+ * });
+ * ```
+ */
 export class Namespace<
   ListenEvents extends EventsMap = DefaultEventsMap,
-  EmitEvents extends EventsMap = ListenEvents
+  EmitEvents extends EventsMap = ListenEvents,
+  ServerSideEvents extends EventsMap = DefaultEventsMap,
+  SocketData = any
 > extends StrictEventEmitter<
-  {},
+  ServerSideEvents,
   EmitEvents,
-  NamespaceReservedEventsMap<ListenEvents, EmitEvents>
+  NamespaceReservedEventsMap<
+    ListenEvents,
+    EmitEvents,
+    ServerSideEvents,
+    SocketData
+  >
 > {
   public readonly name: string;
   public readonly sockets: Map<
     SocketId,
-    Socket<ListenEvents, EmitEvents>
+    Socket<ListenEvents, EmitEvents, ServerSideEvents, SocketData>
   > = new Map();
 
   public adapter: Adapter;
 
   /** @private */
-  readonly server: Server<ListenEvents, EmitEvents>;
+  readonly server: Server<
+    ListenEvents,
+    EmitEvents,
+    ServerSideEvents,
+    SocketData
+  >;
 
   /** @private */
   _fns: Array<
     (
-      socket: Socket<ListenEvents, EmitEvents>,
+      socket: Socket<ListenEvents, EmitEvents, ServerSideEvents, SocketData>,
       next: (err?: ExtendedError) => void
     ) => void
   > = [];
@@ -62,7 +158,10 @@ export class Namespace<
    * @param server instance
    * @param name
    */
-  constructor(server: Server<ListenEvents, EmitEvents>, name: string) {
+  constructor(
+    server: Server<ListenEvents, EmitEvents, ServerSideEvents, SocketData>,
+    name: string
+  ) {
     super();
     this.server = server;
     this.name = name;
@@ -77,18 +176,26 @@ export class Namespace<
    * @private
    */
   _initAdapter(): void {
+    // @ts-ignore
     this.adapter = new (this.server.adapter()!)(this);
   }
 
   /**
-   * Sets up namespace middleware.
+   * Registers a middleware, which is a function that gets executed for every incoming {@link Socket}.
    *
-   * @return self
-   * @public
+   * @example
+   * const myNamespace = io.of("/my-namespace");
+   *
+   * myNamespace.use((socket, next) => {
+   *   // ...
+   *   next();
+   * });
+   *
+   * @param fn - the middleware function
    */
   public use(
     fn: (
-      socket: Socket<ListenEvents, EmitEvents>,
+      socket: Socket<ListenEvents, EmitEvents, ServerSideEvents, SocketData>,
       next: (err?: ExtendedError) => void
     ) => void
   ): this {
@@ -104,7 +211,7 @@ export class Namespace<
    * @private
    */
   private run(
-    socket: Socket<ListenEvents, EmitEvents>,
+    socket: Socket<ListenEvents, EmitEvents, ServerSideEvents, SocketData>,
     fn: (err: ExtendedError | null) => void
   ) {
     const fns = this._fns.slice(0);
@@ -129,34 +236,63 @@ export class Namespace<
   /**
    * Targets a room when emitting.
    *
-   * @param room
-   * @return self
-   * @public
+   * @example
+   * const myNamespace = io.of("/my-namespace");
+   *
+   * // the “foo” event will be broadcast to all connected clients in the “room-101” room
+   * myNamespace.to("room-101").emit("foo", "bar");
+   *
+   * // with an array of rooms (a client will be notified at most once)
+   * myNamespace.to(["room-101", "room-102"]).emit("foo", "bar");
+   *
+   * // with multiple chained calls
+   * myNamespace.to("room-101").to("room-102").emit("foo", "bar");
+   *
+   * @param room - a room, or an array of rooms
+   * @return a new {@link BroadcastOperator} instance for chaining
    */
-  public to(room: Room | Room[]): BroadcastOperator<EmitEvents> {
-    return new BroadcastOperator(this.adapter).to(room);
+  public to(room: Room | Room[]) {
+    return new BroadcastOperator<EmitEvents, SocketData>(this.adapter).to(room);
   }
 
   /**
-   * Targets a room when emitting.
+   * Targets a room when emitting. Similar to `to()`, but might feel clearer in some cases:
    *
-   * @param room
-   * @return self
-   * @public
+   * @example
+   * const myNamespace = io.of("/my-namespace");
+   *
+   * // disconnect all clients in the "room-101" room
+   * myNamespace.in("room-101").disconnectSockets();
+   *
+   * @param room - a room, or an array of rooms
+   * @return a new {@link BroadcastOperator} instance for chaining
    */
-  public in(room: Room | Room[]): BroadcastOperator<EmitEvents> {
-    return new BroadcastOperator(this.adapter).in(room);
+  public in(room: Room | Room[]) {
+    return new BroadcastOperator<EmitEvents, SocketData>(this.adapter).in(room);
   }
 
   /**
    * Excludes a room when emitting.
    *
-   * @param room
-   * @return self
-   * @public
+   * @example
+   * const myNamespace = io.of("/my-namespace");
+   *
+   * // the "foo" event will be broadcast to all connected clients, except the ones that are in the "room-101" room
+   * myNamespace.except("room-101").emit("foo", "bar");
+   *
+   * // with an array of rooms
+   * myNamespace.except(["room-101", "room-102"]).emit("foo", "bar");
+   *
+   * // with multiple chained calls
+   * myNamespace.except("room-101").except("room-102").emit("foo", "bar");
+   *
+   * @param room - a room, or an array of rooms
+   * @return a new {@link BroadcastOperator} instance for chaining
    */
-  public except(room: Room | Room[]): BroadcastOperator<EmitEvents> {
-    return new BroadcastOperator(this.adapter).except(room);
+  public except(room: Room | Room[]) {
+    return new BroadcastOperator<EmitEvents, SocketData>(this.adapter).except(
+      room
+    );
   }
 
   /**
@@ -165,46 +301,93 @@ export class Namespace<
    * @return {Socket}
    * @private
    */
-  _add(
-    client: Client<ListenEvents, EmitEvents>,
-    query,
-    fn?: () => void
-  ): Socket<ListenEvents, EmitEvents> {
+  async _add(
+    client: Client<ListenEvents, EmitEvents, ServerSideEvents>,
+    auth: Record<string, unknown>,
+    fn: (
+      socket: Socket<ListenEvents, EmitEvents, ServerSideEvents, SocketData>
+    ) => void
+  ) {
     debug("adding socket to nsp %s", this.name);
-    const socket = new Socket(this, client, query);
+    const socket = await this._createSocket(client, auth);
+
+    if (
+      // @ts-ignore
+      this.server.opts.connectionStateRecovery?.skipMiddlewares &&
+      socket.recovered &&
+      client.conn.readyState === "open"
+    ) {
+      return this._doConnect(socket, fn);
+    }
+
     this.run(socket, (err) => {
       process.nextTick(() => {
-        if ("open" == client.conn.readyState) {
-          if (err) {
-            if (client.conn.protocol === 3) {
-              return socket._error(err.data || err.message);
-            } else {
-              return socket._error({
-                message: err.message,
-                data: err.data,
-              });
-            }
-          }
-
-          // track socket
-          this.sockets.set(socket.id, socket);
-
-          // it's paramount that the internal `onconnect` logic
-          // fires before user-set events to prevent state order
-          // violations (such as a disconnection before the connection
-          // logic is complete)
-          socket._onconnect();
-          if (fn) fn();
-
-          // fire user-set events
-          this.emitReserved("connect", socket);
-          this.emitReserved("connection", socket);
-        } else {
+        if ("open" !== client.conn.readyState) {
           debug("next called after client was closed - ignoring socket");
+          socket._cleanup();
+          return;
         }
+
+        if (err) {
+          debug("middleware error, sending CONNECT_ERROR packet to the client");
+          socket._cleanup();
+          if (client.conn.protocol === 3) {
+            return socket._error(err.data || err.message);
+          } else {
+            return socket._error({
+              message: err.message,
+              data: err.data,
+            });
+          }
+        }
+
+        this._doConnect(socket, fn);
       });
     });
-    return socket;
+  }
+
+  private async _createSocket(
+    client: Client<ListenEvents, EmitEvents, ServerSideEvents>,
+    auth: Record<string, unknown>
+  ) {
+    const sessionId = auth.pid;
+    const offset = auth.offset;
+    if (
+      // @ts-ignore
+      this.server.opts.connectionStateRecovery &&
+      typeof sessionId === "string" &&
+      typeof offset === "string"
+    ) {
+      const session = await this.adapter.restoreSession(sessionId, offset);
+      if (session) {
+        debug("connection state recovered for sid %s", session.sid);
+        return new Socket(this, client, auth, session);
+      } else {
+        debug("unable to restore session state");
+      }
+    }
+    return new Socket(this, client, auth);
+  }
+
+  private _doConnect(
+    socket: Socket<ListenEvents, EmitEvents, ServerSideEvents, SocketData>,
+    fn: (
+      socket: Socket<ListenEvents, EmitEvents, ServerSideEvents, SocketData>
+    ) => void
+  ) {
+    // track socket
+    this.sockets.set(socket.id, socket);
+
+    // it's paramount that the internal `onconnect` logic
+    // fires before user-set events to prevent state order
+    // violations (such as a disconnection before the connection
+    // logic is complete)
+    socket._onconnect();
+    if (fn) fn(socket);
+
+    // fire user-set events
+    this.emitReserved("connect", socket);
+    this.emitReserved("connection", socket);
   }
 
   /**
@@ -212,7 +395,9 @@ export class Namespace<
    *
    * @private
    */
-  _remove(socket: Socket<ListenEvents, EmitEvents>): void {
+  _remove(
+    socket: Socket<ListenEvents, EmitEvents, ServerSideEvents, SocketData>
+  ): void {
     if (this.sockets.has(socket.id)) {
       this.sockets.delete(socket.id);
     } else {
@@ -221,23 +406,77 @@ export class Namespace<
   }
 
   /**
-   * Emits to all clients.
+   * Emits to all connected clients.
+   *
+   * @example
+   * const myNamespace = io.of("/my-namespace");
+   *
+   * myNamespace.emit("hello", "world");
+   *
+   * // all serializable datastructures are supported (no need to call JSON.stringify)
+   * myNamespace.emit("hello", 1, "2", { 3: ["4"], 5: Uint8Array.from([6]) });
+   *
+   * // with an acknowledgement from the clients
+   * myNamespace.timeout(1000).emit("some-event", (err, responses) => {
+   *   if (err) {
+   *     // some clients did not acknowledge the event in the given delay
+   *   } else {
+   *     console.log(responses); // one response per client
+   *   }
+   * });
    *
    * @return Always true
-   * @public
    */
   public emit<Ev extends EventNames<EmitEvents>>(
     ev: Ev,
     ...args: EventParams<EmitEvents, Ev>
   ): boolean {
-    return new BroadcastOperator<EmitEvents>(this.adapter).emit(ev, ...args);
+    return new BroadcastOperator<EmitEvents, SocketData>(this.adapter).emit(
+      ev,
+      ...args
+    );
+  }
+
+  /**
+   * Emits an event and waits for an acknowledgement from all clients.
+   *
+   * @example
+   * const myNamespace = io.of("/my-namespace");
+   *
+   * try {
+   *   const responses = await myNamespace.timeout(1000).emitWithAck("some-event");
+   *   console.log(responses); // one response per client
+   * } catch (e) {
+   *   // some clients did not acknowledge the event in the given delay
+   * }
+   *
+   * @return a Promise that will be fulfilled when all clients have acknowledged the event
+   */
+  public emitWithAck<Ev extends EventNames<EmitEvents>>(
+    ev: Ev,
+    ...args: AllButLast<EventParams<EmitEvents, Ev>>
+  ): Promise<SecondArg<Last<EventParams<EmitEvents, Ev>>>> {
+    return new BroadcastOperator<EmitEvents, SocketData>(
+      this.adapter
+    ).emitWithAck(ev, ...args);
   }
 
   /**
    * Sends a `message` event to all clients.
    *
+   * This method mimics the WebSocket.send() method.
+   *
+   * @see https://developer.mozilla.org/en-US/docs/Web/API/WebSocket/send
+   *
+   * @example
+   * const myNamespace = io.of("/my-namespace");
+   *
+   * myNamespace.send("hello");
+   *
+   * // this is equivalent to
+   * myNamespace.emit("message", "hello");
+   *
    * @return self
-   * @public
    */
   public send(...args: EventParams<EmitEvents, "message">): this {
     this.emit("message", ...args);
@@ -245,35 +484,134 @@ export class Namespace<
   }
 
   /**
-   * Sends a `message` event to all clients.
+   * Sends a `message` event to all clients. Sends a `message` event. Alias of {@link send}.
    *
    * @return self
-   * @public
    */
   public write(...args: EventParams<EmitEvents, "message">): this {
     this.emit("message", ...args);
     return this;
   }
 
+  /**
+   * Sends a message to the other Socket.IO servers of the cluster.
+   *
+   * @example
+   * const myNamespace = io.of("/my-namespace");
+   *
+   * myNamespace.serverSideEmit("hello", "world");
+   *
+   * myNamespace.on("hello", (arg1) => {
+   *   console.log(arg1); // prints "world"
+   * });
+   *
+   * // acknowledgements (without binary content) are supported too:
+   * myNamespace.serverSideEmit("ping", (err, responses) => {
+   *  if (err) {
+   *     // some servers did not acknowledge the event in the given delay
+   *   } else {
+   *     console.log(responses); // one response per server (except the current one)
+   *   }
+   * });
+   *
+   * myNamespace.on("ping", (cb) => {
+   *   cb("pong");
+   * });
+   *
+   * @param ev - the event name
+   * @param args - an array of arguments, which may include an acknowledgement callback at the end
+   */
+  public serverSideEmit<Ev extends EventNames<ServerSideEvents>>(
+    ev: Ev,
+    ...args: EventParams<
+      DecorateAcknowledgementsWithTimeoutAndMultipleResponses<ServerSideEvents>,
+      Ev
+    >
+  ): boolean {
+    if (RESERVED_EVENTS.has(ev)) {
+      throw new Error(`"${String(ev)}" is a reserved event name`);
+    }
+    args.unshift(ev);
+    this.adapter.serverSideEmit(args);
+    return true;
+  }
+
+  /**
+   * Sends a message and expect an acknowledgement from the other Socket.IO servers of the cluster.
+   *
+   * @example
+   * const myNamespace = io.of("/my-namespace");
+   *
+   * try {
+   *   const responses = await myNamespace.serverSideEmitWithAck("ping");
+   *   console.log(responses); // one response per server (except the current one)
+   * } catch (e) {
+   *   // some servers did not acknowledge the event in the given delay
+   * }
+   *
+   * @param ev - the event name
+   * @param args - an array of arguments
+   *
+   * @return a Promise that will be fulfilled when all servers have acknowledged the event
+   */
+  public serverSideEmitWithAck<Ev extends EventNames<ServerSideEvents>>(
+    ev: Ev,
+    ...args: AllButLast<EventParams<ServerSideEvents, Ev>>
+  ): Promise<FirstArg<Last<EventParams<ServerSideEvents, Ev>>>[]> {
+    return new Promise((resolve, reject) => {
+      args.push((err, responses) => {
+        if (err) {
+          err.responses = responses;
+          return reject(err);
+        } else {
+          return resolve(responses);
+        }
+      });
+      this.serverSideEmit(
+        ev,
+        ...(args as any[] as EventParams<ServerSideEvents, Ev>)
+      );
+    });
+  }
+
+  /**
+   * Called when a packet is received from another Socket.IO server
+   *
+   * @param args - an array of arguments, which may include an acknowledgement callback at the end
+   *
+   * @private
+   */
+  _onServerSideEmit(args: [string, ...any[]]) {
+    super.emitUntyped.apply(this, args);
+  }
+
   /**
    * Gets a list of clients.
    *
-   * @return self
-   * @public
+   * @deprecated this method will be removed in the next major release, please use {@link Namespace#serverSideEmit} or
+   * {@link Namespace#fetchSockets} instead.
    */
   public allSockets(): Promise<Set<SocketId>> {
-    return new BroadcastOperator(this.adapter).allSockets();
+    return new BroadcastOperator<EmitEvents, SocketData>(
+      this.adapter
+    ).allSockets();
   }
 
   /**
    * Sets the compress flag.
    *
+   * @example
+   * const myNamespace = io.of("/my-namespace");
+   *
+   * myNamespace.compress(false).emit("hello");
+   *
    * @param compress - if `true`, compresses the sending data
    * @return self
-   * @public
    */
-  public compress(compress: boolean): BroadcastOperator<EmitEvents> {
-    return new BroadcastOperator(this.adapter).compress(compress);
+  public compress(compress: boolean) {
+    return new BroadcastOperator<EmitEvents, SocketData>(this.adapter).compress(
+      compress
+    );
   }
 
   /**
@@ -281,59 +619,149 @@ export class Namespace<
    * receive messages (because of network slowness or other issues, or because they’re connected through long polling
    * and is in the middle of a request-response cycle).
    *
+   * @example
+   * const myNamespace = io.of("/my-namespace");
+   *
+   * myNamespace.volatile.emit("hello"); // the clients may or may not receive it
+   *
    * @return self
-   * @public
    */
-  public get volatile(): BroadcastOperator<EmitEvents> {
-    return new BroadcastOperator(this.adapter).volatile;
+  public get volatile() {
+    return new BroadcastOperator<EmitEvents, SocketData>(this.adapter).volatile;
   }
 
   /**
    * Sets a modifier for a subsequent event emission that the event data will only be broadcast to the current node.
    *
-   * @return self
-   * @public
-   */
-  public get local(): BroadcastOperator<EmitEvents> {
-    return new BroadcastOperator(this.adapter).local;
-  }
-
-  /**
-   * Returns the matching socket instances
+   * @example
+   * const myNamespace = io.of("/my-namespace");
    *
-   * @public
-   */
-  public fetchSockets(): Promise<RemoteSocket<EmitEvents>[]> {
-    return new BroadcastOperator(this.adapter).fetchSockets();
-  }
-
-  /**
-   * Makes the matching socket instances join the specified rooms
+   * // the “foo” event will be broadcast to all connected clients on this node
+   * myNamespace.local.emit("foo", "bar");
    *
-   * @param room
-   * @public
+   * @return a new {@link BroadcastOperator} instance for chaining
    */
-  public socketsJoin(room: Room | Room[]): void {
-    return new BroadcastOperator(this.adapter).socketsJoin(room);
+  public get local() {
+    return new BroadcastOperator<EmitEvents, SocketData>(this.adapter).local;
   }
 
   /**
-   * Makes the matching socket instances leave the specified rooms
+   * Adds a timeout in milliseconds for the next operation.
    *
-   * @param room
-   * @public
+   * @example
+   * const myNamespace = io.of("/my-namespace");
+   *
+   * myNamespace.timeout(1000).emit("some-event", (err, responses) => {
+   *   if (err) {
+   *     // some clients did not acknowledge the event in the given delay
+   *   } else {
+   *     console.log(responses); // one response per client
+   *   }
+   * });
+   *
+   * @param timeout
    */
-  public socketsLeave(room: Room | Room[]): void {
-    return new BroadcastOperator(this.adapter).socketsLeave(room);
+  public timeout(timeout: number) {
+    return new BroadcastOperator<EmitEvents, SocketData>(this.adapter).timeout(
+      timeout
+    );
   }
 
   /**
-   * Makes the matching socket instances disconnect
+   * Returns the matching socket instances.
+   *
+   * Note: this method also works within a cluster of multiple Socket.IO servers, with a compatible {@link Adapter}.
+   *
+   * @example
+   * const myNamespace = io.of("/my-namespace");
+   *
+   * // return all Socket instances
+   * const sockets = await myNamespace.fetchSockets();
+   *
+   * // return all Socket instances in the "room1" room
+   * const sockets = await myNamespace.in("room1").fetchSockets();
+   *
+   * for (const socket of sockets) {
+   *   console.log(socket.id);
+   *   console.log(socket.handshake);
+   *   console.log(socket.rooms);
+   *   console.log(socket.data);
+   *
+   *   socket.emit("hello");
+   *   socket.join("room1");
+   *   socket.leave("room2");
+   *   socket.disconnect();
+   * }
+   */
+  public fetchSockets() {
+    return new BroadcastOperator<EmitEvents, SocketData>(
+      this.adapter
+    ).fetchSockets();
+  }
+
+  /**
+   * Makes the matching socket instances join the specified rooms.
+   *
+   * Note: this method also works within a cluster of multiple Socket.IO servers, with a compatible {@link Adapter}.
+   *
+   * @example
+   * const myNamespace = io.of("/my-namespace");
+   *
+   * // make all socket instances join the "room1" room
+   * myNamespace.socketsJoin("room1");
+   *
+   * // make all socket instances in the "room1" room join the "room2" and "room3" rooms
+   * myNamespace.in("room1").socketsJoin(["room2", "room3"]);
+   *
+   * @param room - a room, or an array of rooms
+   */
+  public socketsJoin(room: Room | Room[]) {
+    return new BroadcastOperator<EmitEvents, SocketData>(
+      this.adapter
+    ).socketsJoin(room);
+  }
+
+  /**
+   * Makes the matching socket instances leave the specified rooms.
+   *
+   * Note: this method also works within a cluster of multiple Socket.IO servers, with a compatible {@link Adapter}.
+   *
+   * @example
+   * const myNamespace = io.of("/my-namespace");
+   *
+   * // make all socket instances leave the "room1" room
+   * myNamespace.socketsLeave("room1");
+   *
+   * // make all socket instances in the "room1" room leave the "room2" and "room3" rooms
+   * myNamespace.in("room1").socketsLeave(["room2", "room3"]);
+   *
+   * @param room - a room, or an array of rooms
+   */
+  public socketsLeave(room: Room | Room[]) {
+    return new BroadcastOperator<EmitEvents, SocketData>(
+      this.adapter
+    ).socketsLeave(room);
+  }
+
+  /**
+   * Makes the matching socket instances disconnect.
+   *
+   * Note: this method also works within a cluster of multiple Socket.IO servers, with a compatible {@link Adapter}.
+   *
+   * @example
+   * const myNamespace = io.of("/my-namespace");
+   *
+   * // make all socket instances disconnect (the connections might be kept alive for other namespaces)
+   * myNamespace.disconnectSockets();
+   *
+   * // make all socket instances in the "room1" room disconnect and close the underlying connections
+   * myNamespace.in("room1").disconnectSockets(true);
    *
    * @param close - whether to close the underlying connection
-   * @public
    */
-  public disconnectSockets(close: boolean = false): void {
-    return new BroadcastOperator(this.adapter).disconnectSockets(close);
+  public disconnectSockets(close: boolean = false) {
+    return new BroadcastOperator<EmitEvents, SocketData>(
+      this.adapter
+    ).disconnectSockets(close);
   }
 }

lib/parent-namespace.ts

@@ -1,5 +1,5 @@
 import { Namespace } from "./namespace";
-import type { Server } from "./index";
+import type { Server, RemoteSocket } from "./index";
 import type {
   EventParams,
   EventNames,
@@ -7,15 +7,24 @@ import type {
   DefaultEventsMap,
 } from "./typed-events";
 import type { BroadcastOptions } from "socket.io-adapter";
+import debugModule from "debug";
+
+const debug = debugModule("socket.io:parent-namespace");
 
 export class ParentNamespace<
   ListenEvents extends EventsMap = DefaultEventsMap,
-  EmitEvents extends EventsMap = ListenEvents
-> extends Namespace<ListenEvents, EmitEvents> {
+  EmitEvents extends EventsMap = ListenEvents,
+  ServerSideEvents extends EventsMap = DefaultEventsMap,
+  SocketData = any
+> extends Namespace<ListenEvents, EmitEvents, ServerSideEvents, SocketData> {
   private static count: number = 0;
-  private children: Set<Namespace<ListenEvents, EmitEvents>> = new Set();
+  private children: Set<
+    Namespace<ListenEvents, EmitEvents, ServerSideEvents, SocketData>
+  > = new Set();
 
-  constructor(server: Server<ListenEvents, EmitEvents>) {
+  constructor(
+    server: Server<ListenEvents, EmitEvents, ServerSideEvents, SocketData>
+  ) {
     super(server, "/_" + ParentNamespace.count++);
   }
 
@@ -43,7 +52,10 @@ export class ParentNamespace<
     return true;
   }
 
-  createChild(name: string): Namespace<ListenEvents, EmitEvents> {
+  createChild(
+    name: string
+  ): Namespace<ListenEvents, EmitEvents, ServerSideEvents, SocketData> {
+    debug("creating child namespace %s", name);
     const namespace = new Namespace(this.server, name);
     namespace._fns = this._fns.slice(0);
     this.listeners("connect").forEach((listener) =>
@@ -53,7 +65,31 @@ export class ParentNamespace<
       namespace.on("connection", listener)
     );
     this.children.add(namespace);
+
+    if (this.server._opts.cleanupEmptyChildNamespaces) {
+      const remove = namespace._remove;
+
+      namespace._remove = (socket) => {
+        remove.call(namespace, socket);
+        if (namespace.sockets.size === 0) {
+          debug("closing child namespace %s", name);
+          namespace.adapter.close();
+          this.server._nsps.delete(namespace.name);
+          this.children.delete(namespace);
+        }
+      };
+    }
+
     this.server._nsps.set(name, namespace);
     return namespace;
   }
+
+  fetchSockets(): Promise<RemoteSocket<EmitEvents, SocketData>[]> {
+    // note: we could make the fetchSockets() method work for dynamic namespaces created with a regex (by sending the
+    // regex to the other Socket.IO servers, and returning the sockets of each matching namespace for example), but
+    // the behavior for namespaces created with a function is less clear
+    // note²: we cannot loop over each children namespace, because with multiple Socket.IO servers, a given namespace
+    // may exist on one node but not exist on another (since it is created upon client connection)
+    throw new Error("fetchSockets() is not supported on parent namespaces");
+  }
 }