chore(release): 4.7.4

Diff: https://github.com/socketio/socket.io/compare/4.7.3...4.7.4

.github/workflows/ci.yml

@@ -6,22 +6,34 @@ on:
   schedule:
     - cron: '0 0 * * 0'
 
+permissions:
+  contents: read
+
 jobs:
   test-node:
     runs-on: ubuntu-latest
+    timeout-minutes: 10
 
     strategy:
       matrix:
-        node-version: [12, 14, 16]
+        node-version:
+          - 16
+          - 20
 
     steps:
-      - uses: actions/checkout@v2
+      - name: Checkout repository
+        uses: actions/checkout@v3
+
       - name: Use Node.js ${{ matrix.node-version }}
-        uses: actions/setup-node@v2
+        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
 
@@ -37,16 +49,18 @@ jobs:
           - typescript
           - webpack-build
           - webpack-build-server
+          - basic-crud-application/angular-client
+          - basic-crud-application/vue-client
 
     steps:
       - name: Checkout repository
         uses: actions/checkout@v3
-        
+
       - name: Use Node.js 20
         uses: actions/setup-node@v3
         with:
           node-version: 20
-          
+
       - name: Build ${{ matrix.example }}
         run: |
           cd examples/${{ matrix.example }}

CHANGELOG.md

@@ -1,3 +1,565 @@
+# History
+
+## 2024
+
+- [4.7.4](#474-2024-01-12) (Jan 2024)
+- [4.7.3](#473-2024-01-03) (Jan 2024)
+
+## 2023
+
+- [4.7.2](#472-2023-08-02) (Aug 2023)
+- [4.7.1](#471-2023-06-28) (Jun 2023)
+- [4.7.0](#470-2023-06-22) (Jun 2023)
+- [4.6.2](#462-2023-05-31) (May 2023)
+- [4.6.1](#461-2023-02-20) (Feb 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
+
+## [4.7.4](https://github.com/socketio/socket.io/compare/4.7.3...4.7.4) (2024-01-12)
+
+
+### Bug Fixes
+
+* **typings:** calling io.emit with no arguments incorrectly errored ([cb6d2e0](https://github.com/socketio/socket.io/commit/cb6d2e02aa7ec03c2de1817d35cffa1128b107ef)), closes [#4914](https://github.com/socketio/socket.io/issues/4914)
+
+
+### Dependencies
+
+- [`engine.io@~6.5.2`](https://github.com/socketio/engine.io/releases/tag/6.5.2) (no change)
+- [`ws@~8.11.0`](https://github.com/websockets/ws/releases/tag/8.11.0) (no change)
+
+
+
+## [4.7.3](https://github.com/socketio/socket.io/compare/4.7.2...4.7.3) (2024-01-03)
+
+
+### Bug Fixes
+
+* return the first response when broadcasting to a single socket ([#4878](https://github.com/socketio/socket.io/issues/4878)) ([df8e70f](https://github.com/socketio/socket.io/commit/df8e70f79822e3887b4f21ca718af8a53bbda2c4))
+* **typings:** allow to bind to a non-secure Http2Server ([#4853](https://github.com/socketio/socket.io/issues/4853)) ([8c9ebc3](https://github.com/socketio/socket.io/commit/8c9ebc30e5452ff9381af5d79f547394fa55633c))
+
+
+### Dependencies
+
+- [`engine.io@~6.5.2`](https://github.com/socketio/engine.io/releases/tag/6.5.2) (no change)
+- [`ws@~8.11.0`](https://github.com/websockets/ws/releases/tag/8.11.0) (no change)
+
+
+
+## [4.7.2](https://github.com/socketio/socket.io/compare/4.7.1...4.7.2) (2023-08-02)
+
+
+### Bug Fixes
+
+* clean up child namespace when client is rejected in middleware ([#4773](https://github.com/socketio/socket.io/issues/4773)) ([0731c0d](https://github.com/socketio/socket.io/commit/0731c0d2f497d5cce596ea1ec32a67c08bcccbcd))
+* **webtransport:** properly handle WebTransport-only connections ([3468a19](https://github.com/socketio/socket.io/commit/3468a197afe87e65eb0d779fabd347fe683013ab))
+* **webtransport:** add proper framing ([a306db0](https://github.com/socketio/engine.io/commit/a306db09e8ddb367c7d62f45fec920f979580b7c))
+
+
+### Dependencies
+
+- [`engine.io@~6.5.2`](https://github.com/socketio/engine.io/releases/tag/6.5.2) ([diff](https://github.com/socketio/engine.io/compare/6.5.0...6.5.2))
+- [`ws@~8.11.0`](https://github.com/websockets/ws/releases/tag/8.11.0) (no change)
+
+
+
+## [4.7.1](https://github.com/socketio/socket.io/compare/4.7.0...4.7.1) (2023-06-28)
+
+The client bundle contains a few fixes regarding the WebTransport support.
+
+### Dependencies
+
+- [`engine.io@~6.5.0`](https://github.com/socketio/engine.io/releases/tag/6.5.0) (no change)
+- [`ws@~8.11.0`](https://github.com/websockets/ws/releases/tag/8.11.0) (no change)
+
+
+
+## [4.7.0](https://github.com/socketio/socket.io/compare/4.6.2...4.7.0) (2023-06-22)
+
+
+### Bug Fixes
+
+* remove the Partial modifier from the socket.data type ([#4740](https://github.com/socketio/socket.io/issues/4740)) ([e5c62ca](https://github.com/socketio/socket.io/commit/e5c62cad60fc7d16fbb024fd9be1d1880f4e6f5f))
+
+
+### Features
+
+#### Support for WebTransport
+
+The Socket.IO server can now use WebTransport as the underlying transport.
+
+WebTransport is a web API that uses the HTTP/3 protocol as a bidirectional transport. It's intended for two-way communications between a web client and an HTTP/3 server.
+
+References:
+
+- https://w3c.github.io/webtransport/
+- https://developer.mozilla.org/en-US/docs/Web/API/WebTransport
+- https://developer.chrome.com/articles/webtransport/
+
+Until WebTransport support lands [in Node.js](https://github.com/nodejs/node/issues/38478), you can use the `@fails-components/webtransport` package:
+
+```js
+import { readFileSync } from "fs";
+import { createServer } from "https";
+import { Server } from "socket.io";
+import { Http3Server } from "@fails-components/webtransport";
+
+// WARNING: the total length of the validity period MUST NOT exceed two weeks (https://w3c.github.io/webtransport/#custom-certificate-requirements)
+const cert = readFileSync("/path/to/my/cert.pem");
+const key = readFileSync("/path/to/my/key.pem");
+
+const httpsServer = createServer({
+  key,
+  cert
+});
+
+httpsServer.listen(3000);
+
+const io = new Server(httpsServer, {
+  transports: ["polling", "websocket", "webtransport"] // WebTransport is not enabled by default
+});
+
+const h3Server = new Http3Server({
+  port: 3000,
+  host: "0.0.0.0",
+  secret: "changeit",
+  cert,
+  privKey: key,
+});
+
+(async () => {
+  const stream = await h3Server.sessionStream("/socket.io/");
+  const sessionReader = stream.getReader();
+
+  while (true) {
+    const { done, value } = await sessionReader.read();
+    if (done) {
+      break;
+    }
+    io.engine.onWebTransportSession(value);
+  }
+})();
+
+h3Server.startServer();
+```
+
+Added in [123b68c](https://github.com/socketio/engine.io/commit/123b68c04f9e971f59b526e0f967a488ee6b0116).
+
+
+#### Client bundles with CORS headers
+
+The bundles will now have the right `Access-Control-Allow-xxx` headers.
+
+Added in [63f181c](https://github.com/socketio/socket.io/commit/63f181cc12cbbbf94ed40eef52d60f36a1214fbe).
+
+
+### Dependencies
+
+- [`engine.io@~6.5.0`](https://github.com/socketio/engine.io/releases/tag/6.5.0) ([diff](https://github.com/socketio/engine.io/compare/6.4.2...6.5.0))
+- [`ws@~8.11.0`](https://github.com/websockets/ws/releases/tag/8.11.0) (no change)
+
+
+
+## [4.6.2](https://github.com/socketio/socket.io/compare/4.6.1...4.6.2) (2023-05-31)
+
+
+### Bug Fixes
+
+* **exports:** move `types` condition to the top ([#4698](https://github.com/socketio/socket.io/issues/4698)) ([3d44aae](https://github.com/socketio/socket.io/commit/3d44aae381af38349fdb808d510d9f47a0c2507e))
+
+
+### Dependencies
+
+- [`engine.io@~6.4.2`](https://github.com/socketio/engine.io/releases/tag/6.4.0) ([diff](https://github.com/socketio/engine.io/compare/6.4.1...6.4.2))
+- [`ws@~8.11.0`](https://github.com/websockets/ws/releases/tag/8.11.0) (no change)
+
+
+
+## [4.6.1](https://github.com/socketio/socket.io/compare/4.6.0...4.6.1) (2023-02-20)
+
+
+### Bug Fixes
+
+* properly handle manually created dynamic namespaces ([0d0a7a2](https://github.com/socketio/socket.io/commit/0d0a7a22b5ff95f864216c529114b7dd41738d1e))
+* **types:** fix nodenext module resolution compatibility ([#4625](https://github.com/socketio/socket.io/issues/4625)) ([d0b22c6](https://github.com/socketio/socket.io/commit/d0b22c630208669aceb7ae013180c99ef90279b0))
+
+
+### Dependencies
+
+- [`engine.io@~6.4.1`](https://github.com/socketio/engine.io/releases/tag/6.4.1) ([diff](https://github.com/socketio/engine.io/compare/6.4.0...6.4.1))
+- [`ws@~8.11.0`](https://github.com/websockets/ws/releases/tag/8.11.0) (no change)
+
+
+
+## [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) (https://github.com/socketio/engine.io/compare/6.2.1...6.4.0)
+- [`ws@~8.11.0`](https://github.com/websockets/ws/releases/tag/8.11.0) (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))
+
+### Dependencies
+
+- [`engine.io@~6.2.0`](https://github.com/socketio/engine.io/releases/tag/6.2.1) (no change)
+- [`ws@~8.2.3`](https://github.com/websockets/ws/releases/tag/8.2.3) (no change)
+
+
+
+## [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))
+
+### Dependencies
+
+- [`engine.io@~6.2.0`](https://github.com/socketio/engine.io/releases/tag/6.2.0) (no change)
+- [`ws@~8.2.3`](https://github.com/websockets/ws/releases/tag/8.2.3) (no change)
+
+
+
+# [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))
+
+### Dependencies
+
+- [`engine.io@~3.6.0`](https://github.com/socketio/engine.io/releases/tag/3.6.0) (https://github.com/socketio/engine.io/compare/3.5.0...3.6.0)
+- [`ws@~7.4.2`](https://github.com/websockets/ws/releases/tag/7.4.2) (no change)
+
+
+
+## [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))
+
+### Dependencies
+
+- [`engine.io@~6.2.0`](https://github.com/socketio/engine.io/releases/tag/6.2.0) (no change)
+- [`ws@~8.2.3`](https://github.com/websockets/ws/releases/tag/8.2.3) (no change)
+
+
+
+# [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
+
+#### Catch-all listeners for outgoing packets
+
+This is similar to `onAny()`, but for outgoing packets.
+
+Syntax:
+
+```js
+socket.onAnyOutgoing((event, ...args) => {
+  console.log(event);
+});
+```
+
+Added in [531104d](https://github.com/socketio/socket.io/commit/531104d332690138b7aab84d5583d6204132c8b4).
+
+#### Broadcast and expect multiple acknowledgements
+
+Syntax:
+
+```js
+io.timeout(1000).emit("some-event", (err, responses) => {
+  // ...
+});
+```
+
+Added in [8b20457](https://github.com/socketio/socket.io/commit/8b204570a94979bbec307f23ca078f30f5cf07b0).
+
+#### `maxHttpBufferSize` value negotiation
+
+A "maxPayload" field is now included in the Engine.IO handshake, 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}
+```
+
+Added in [088dcb4](https://github.com/socketio/engine.io/commit/088dcb4dff60df39785df13d0a33d3ceaa1dff38).
+
+### Dependencies
+
+- [`engine.io@~6.2.0`](https://github.com/socketio/engine.io/releases/tag/6.2.0) (https://github.com/socketio/engine.io/compare/6.1.0...6.2.0)
+- [`ws@~8.2.3`](https://github.com/websockets/ws/releases/tag/8.2.3) (no change)
+
+
+
 ## [4.4.1](https://github.com/socketio/socket.io/compare/4.4.0...4.4.1) (2022-01-06)
 
 
@@ -178,6 +740,16 @@
 * 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)
 
 
@@ -191,6 +763,17 @@
 * 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)
 
 
@@ -308,7 +891,7 @@ new Server(3000, {
 const socket = io("/admin");
 
 // server-side
-io.on("connect", socket => {
+io.on("connection", socket => {
   // not triggered anymore
 })
 
@@ -459,7 +1042,7 @@ new Server(3000, {
 const socket = io("/admin");
 
 // server-side
-io.on("connect", socket => {
+io.on("connection", socket => {
   // not triggered anymore
 })
 
@@ -476,3 +1059,78 @@ 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

@@ -21,6 +21,8 @@ Some implementations in other languages are also available:
 - [Dart](https://github.com/rikulo/socket.io-client-dart)
 - [Python](https://github.com/miguelgrinberg/python-socketio)
 - [.NET](https://github.com/doghappy/socket.io-client-csharp)
+- [Rust](https://github.com/1c3t3a/rust-socketio)
+- [PHP](https://github.com/ElephantIO/elephant.io)
 
 Its main features are:
 
@@ -125,7 +127,7 @@ io.listen(3000);
 
 Starting with **3.0**, express applications have become request handler
 functions that you pass to `http` or `http` `Server` instances. You need
-to pass the `Server` to `socket.io`, and not the express application
+to pass the `Server` to `socket.io`, not the express application
 function. Also make sure to call `.listen` on the `server`, not the `app`.
 
 ```js

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/angular-todomvc/server.ts

@@ -15,7 +15,7 @@ interface Todo {
 
 let todos: Array<Todo> = [];
 
-io.on("connect", (socket) => {
+io.on("connection", (socket) => {
     socket.emit("todos", todos);
 
     // note: we could also create a CRUD (create/read/update/delete) service for the todo list

examples/basic-crud-application/README.md

@@ -2,6 +2,13 @@
 
 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
 
 ```

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

@@ -1,17 +0,0 @@
-# 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/.gitignore

@@ -1,21 +1,18 @@
 # See http://help.github.com/ignore-files/ for more about ignoring files.
 
-# compiled output
+# Compiled output
 /dist
 /tmp
 /out-tsc
-# Only exists if Bazel was run
 /bazel-out
 
-# dependencies
+# Node
 /node_modules
-
-# profiling files
-chrome-profiler-events*.json
-speed-measure-plugin*.json
+npm-debug.log
+yarn-error.log
 
 # IDEs and editors
-/.idea
+.idea/
 .project
 .classpath
 .c9/
@@ -23,7 +20,7 @@ speed-measure-plugin*.json
 .settings/
 *.sublime-workspace
 
-# IDE - VSCode
+# Visual Studio Code
 .vscode/*
 !.vscode/settings.json
 !.vscode/tasks.json
@@ -31,16 +28,15 @@ speed-measure-plugin*.json
 !.vscode/extensions.json
 .history/*
 
-# misc
-/.sass-cache
+# Miscellaneous
+/.angular/cache
+.sass-cache/
 /connect.lock
 /coverage
 /libpeerconnection.log
-npm-debug.log
-yarn-error.log
 testem.log
 /typings
 
-# System Files
+# System files
 .DS_Store
 Thumbs.db

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

@@ -1,14 +1,10 @@
-# Angular TodoMVC + Socket.IO
+# AngularClient
 
-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)
+This project was generated with [Angular CLI](https://github.com/angular/angular-cli) version 17.0.2.
 
 ## 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.
+Run `ng serve` for a dev server. Navigate to `http://localhost:4200/`. The application will automatically reload if you change any of the source files.
 
 ## Code scaffolding
 
@@ -16,7 +12,7 @@ Run `ng generate component component-name` to generate a new component. You can
 
 ## 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.
+Run `ng build` to build the project. The build artifacts will be stored in the `dist/` directory.
 
 ## Running unit tests
 
@@ -24,7 +20,7 @@ Run `ng test` to execute the unit tests via [Karma](https://karma-runner.github.
 
 ## Running end-to-end tests
 
-Run `ng e2e` to execute the end-to-end tests via [Protractor](http://www.protractortest.org/).
+Run `ng e2e` to execute the end-to-end tests via a platform of your choice. To use this command, you need to first add a package that implements end-to-end testing capabilities.
 
 ## Further help
 

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

@@ -3,26 +3,23 @@
   "version": 1,
   "newProjectRoot": "projects",
   "projects": {
-    "angular-todomvc": {
+    "angular-client": {
       "projectType": "application",
-      "schematics": {
-        "@schematics/angular:application": {
-          "strict": true
-        }
-      },
+      "schematics": {},
       "root": "",
       "sourceRoot": "src",
       "prefix": "app",
       "architect": {
         "build": {
-          "builder": "@angular-devkit/build-angular:browser",
+          "builder": "@angular-devkit/build-angular:application",
           "options": {
-            "outputPath": "dist/angular-todomvc",
+            "outputPath": "dist/angular-client",
             "index": "src/index.html",
-            "main": "src/main.ts",
-            "polyfills": "src/polyfills.ts",
+            "browser": "src/main.ts",
+            "polyfills": [
+              "zone.js"
+            ],
             "tsConfig": "tsconfig.app.json",
-            "aot": true,
             "assets": [
               "src/favicon.ico",
               "src/assets"
@@ -34,19 +31,6 @@
           },
           "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",
@@ -58,34 +42,49 @@
                   "maximumWarning": "2kb",
                   "maximumError": "4kb"
                 }
+              ],
+              "outputHashing": "all"
+            },
+            "development": {
+              "optimization": false,
+              "extractLicenses": false,
+              "sourceMap": true,
+              "fileReplacements": [
+                {
+                  "replace": "src/environments/environment.ts",
+                  "with": "src/environments/environment.development.ts"
+                }
               ]
             }
-          }
+          },
+          "defaultConfiguration": "production"
         },
         "serve": {
           "builder": "@angular-devkit/build-angular:dev-server",
-          "options": {
-            "browserTarget": "angular-todomvc:build"
-          },
           "configurations": {
             "production": {
-              "browserTarget": "angular-todomvc:build:production"
+              "buildTarget": "angular-client:build:production"
+            },
+            "development": {
+              "buildTarget": "angular-client:build:development"
             }
-          }
+          },
+          "defaultConfiguration": "development"
         },
         "extract-i18n": {
           "builder": "@angular-devkit/build-angular:extract-i18n",
           "options": {
-            "browserTarget": "angular-todomvc:build"
+            "buildTarget": "angular-client:build"
           }
         },
         "test": {
           "builder": "@angular-devkit/build-angular:karma",
           "options": {
-            "main": "src/test.ts",
-            "polyfills": "src/polyfills.ts",
+            "polyfills": [
+              "zone.js",
+              "zone.js/testing"
+            ],
             "tsConfig": "tsconfig.spec.json",
-            "karmaConfig": "karma.conf.js",
             "assets": [
               "src/favicon.ico",
               "src/assets"
@@ -95,34 +94,8 @@
             ],
             "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

@@ -1,37 +0,0 @@
-// @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

@@ -1,23 +0,0 @@
-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

@@ -1,11 +0,0 @@
-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

@@ -1,13 +0,0 @@
-/* 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

@@ -1,44 +0,0 @@
-// 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

@@ -1,46 +1,40 @@
 {
-  "name": "angular-todomvc",
+  "name": "angular-client",
   "version": "0.0.0",
   "scripts": {
     "ng": "ng",
     "start": "ng serve",
     "build": "ng build",
-    "test": "ng test",
-    "lint": "ng lint",
-    "e2e": "ng e2e"
+    "watch": "ng build --watch --configuration development",
+    "test": "ng test"
   },
   "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"
+    "@angular/animations": "^17.0.0",
+    "@angular/common": "^17.0.0",
+    "@angular/compiler": "^17.0.0",
+    "@angular/core": "^17.0.0",
+    "@angular/forms": "^17.0.0",
+    "@angular/platform-browser": "^17.0.0",
+    "@angular/platform-browser-dynamic": "^17.0.0",
+    "@angular/router": "^17.0.0",
+    "rxjs": "~7.8.0",
+    "socket.io-client": "^4.7.2",
+    "tslib": "^2.3.0",
+    "zone.js": "~0.14.2"
   },
   "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"
+    "@angular-devkit/build-angular": "^17.0.2",
+    "@angular/cli": "^17.0.2",
+    "@angular/compiler-cli": "^17.0.0",
+    "@types/jasmine": "~5.1.0",
+    "@types/node": "^20.9.2",
+    "jasmine-core": "~5.1.0",
+    "karma": "~6.4.0",
+    "karma-chrome-launcher": "~3.2.0",
+    "karma-coverage": "~2.2.0",
+    "karma-jasmine": "~5.1.0",
+    "karma-jasmine-html-reporter": "~2.1.0",
+    "typescript": "~5.2.2"
   }
 }

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

@@ -1,7 +1,8 @@
 <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()">
+<!--    <input class="new-todo" placeholder="What needs to be done?" autofocus="" [(ngModel)]="newTodoText" (keyup.enter)="addTodo()">-->
+    <input class="new-todo" placeholder="What needs to be done?" autofocus="" [formControl]="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)">

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

@@ -4,9 +4,7 @@ import { AppComponent } from './app.component';
 describe('AppComponent', () => {
   beforeEach(async () => {
     await TestBed.configureTestingModule({
-      declarations: [
-        AppComponent
-      ],
+      imports: [AppComponent],
     }).compileComponents();
   });
 
@@ -16,16 +14,16 @@ describe('AppComponent', () => {
     expect(app).toBeTruthy();
   });
 
-  it(`should have as title 'angular-todomvc'`, () => {
+  it(`should have the 'angular-client' title`, () => {
     const fixture = TestBed.createComponent(AppComponent);
     const app = fixture.componentInstance;
-    expect(app.title).toEqual('angular-todomvc');
+    expect(app.title).toEqual('angular-client');
   });
 
   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!');
+    const compiled = fixture.nativeElement as HTMLElement;
+    expect(compiled.querySelector('h1')?.textContent).toContain('Hello, angular-client');
   });
 });

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

@@ -1,17 +1,21 @@
 import { Component } from '@angular/core';
-import { TodoStore, Todo } from './store';
+import { CommonModule } from '@angular/common';
+import { RouterOutlet } from '@angular/router';
+import {type Todo, TodoStore} from "./store";
+import { FormControl, ReactiveFormsModule } from '@angular/forms';
 
 @Component({
   selector: 'app-root',
+  standalone: true,
+  imports: [CommonModule, RouterOutlet, ReactiveFormsModule],
   templateUrl: './app.component.html',
-  styleUrls: ['./app.component.css']
+  styleUrl: './app.component.css',
+  providers: [TodoStore]
 })
 export class AppComponent {
-  todoStore: TodoStore;
-  newTodoText = '';
+  newTodoText = new FormControl('');
 
-  constructor(todoStore: TodoStore) {
-    this.todoStore = todoStore;
+  constructor(readonly todoStore: TodoStore) {
   }
 
   stopEditing(todo: Todo, editedTitle: string) {
@@ -51,9 +55,9 @@ export class AppComponent {
   }
 
   addTodo() {
-    if (this.newTodoText.trim().length) {
-      this.todoStore.add(this.newTodoText);
-      this.newTodoText = '';
+    if (this.newTodoText.value?.trim().length) {
+      this.todoStore.add(this.newTodoText.value!);
+      this.newTodoText.setValue('');
     }
   }
 }

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

@@ -0,0 +1,8 @@
+import { ApplicationConfig } from '@angular/core';
+import { provideRouter } from '@angular/router';
+
+import { routes } from './app.routes';
+
+export const appConfig: ApplicationConfig = {
+  providers: [provideRouter(routes)]
+};

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

@@ -1,19 +0,0 @@
-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/app.routes.ts

@@ -0,0 +1,3 @@
+import { Routes } from '@angular/router';
+
+export const routes: Routes = [];

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

@@ -1,6 +1,7 @@
 import { io, Socket } from "socket.io-client";
-import { ClientEvents, ServerEvents } from "../../../server/lib/events";
+import { ClientEvents, ServerEvents } from "../../../common/events";
 import { environment } from '../environments/environment';
+import {Injectable} from "@angular/core";
 
 export interface Todo {
   id: string,
@@ -18,6 +19,7 @@ const mapTodo = (todo: any) => {
   }
 }
 
+@Injectable()
 export class TodoStore {
   public todos: Array<Todo> = [];
   private socket: Socket<ServerEvents, ClientEvents>;

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

@@ -0,0 +1,3 @@
+export const environment = {
+  serverUrl: "http://localhost:3000"
+};

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

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

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

@@ -1,17 +1,3 @@
-// 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"
+  serverUrl: "https://my-custom-domain.com"
 };
-
-/*
- * 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

@@ -2,7 +2,7 @@
 <html lang="en">
 <head>
   <meta charset="utf-8">
-  <title>Angular Todo MVC</title>
+  <title>AngularClient</title>
   <base href="/">
   <meta name="viewport" content="width=device-width, initial-scale=1">
   <link rel="icon" type="image/x-icon" href="favicon.ico">

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

@@ -1,12 +1,6 @@
-import { enableProdMode } from '@angular/core';
-import { platformBrowserDynamic } from '@angular/platform-browser-dynamic';
+import { bootstrapApplication } from '@angular/platform-browser';
+import { appConfig } from './app/app.config';
+import { AppComponent } from './app/app.component';
 
-import { AppModule } from './app/app.module';
-import { environment } from './environments/environment';
-
-if (environment.production) {
-  enableProdMode();
-}
-
-platformBrowserDynamic().bootstrapModule(AppModule)
-  .catch(err => console.error(err));
+bootstrapApplication(AppComponent, appConfig)
+  .catch((err) => console.error(err));

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

@@ -1,63 +0,0 @@
-/**
- * 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/test.ts

@@ -1,25 +0,0 @@
-// 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

@@ -6,8 +6,7 @@
     "types": []
   },
   "files": [
-    "src/main.ts",
-    "src/polyfills.ts"
+    "src/main.ts"
   ],
   "include": [
     "src/**/*.d.ts"

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

@@ -2,26 +2,29 @@
 {
   "compileOnSave": false,
   "compilerOptions": {
-    "baseUrl": "./",
     "outDir": "./dist/out-tsc",
     "forceConsistentCasingInFileNames": true,
     "strict": true,
+    "noImplicitOverride": true,
+    "noPropertyAccessFromIndexSignature": true,
     "noImplicitReturns": true,
     "noFallthroughCasesInSwitch": true,
+    "esModuleInterop": true,
     "sourceMap": true,
     "declaration": false,
-    "downlevelIteration": true,
     "experimentalDecorators": true,
     "moduleResolution": "node",
     "importHelpers": true,
-    "target": "es2015",
-    "module": "es2020",
+    "target": "ES2022",
+    "module": "ES2022",
+    "useDefineForClassFields": false,
     "lib": [
-      "es2018",
+      "ES2022",
       "dom"
     ]
   },
   "angularCompilerOptions": {
+    "enableI18nLegacyMessageIdFormat": false,
     "strictInjectionParameters": true,
     "strictInputAccessModifiers": true,
     "strictTemplates": true

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

@@ -7,10 +7,6 @@
       "jasmine"
     ]
   },
-  "files": [
-    "src/test.ts",
-    "src/polyfills.ts"
-  ],
   "include": [
     "src/**/*.spec.ts",
     "src/**/*.d.ts"

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

@@ -1,152 +0,0 @@
-{
-  "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/common/events.ts

@@ -1,9 +1,18 @@
-import { Todo, TodoID } from "./todo-management/todo.repository";
-import { ValidationErrorItem } from "joi";
+export type TodoID = string;
+
+export interface Todo {
+  id: TodoID;
+  completed: boolean;
+  title: string;
+}
 
 interface Error {
   error: string;
-  errorDetails?: ValidationErrorItem[];
+  errorDetails?: {
+    message: string;
+    path: Array<string | number>;
+    type: string;
+  }[];
 }
 
 interface Success<T> {

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

@@ -1,6 +1,6 @@
 import { Server as HttpServer } from "http";
 import { Server, ServerOptions } from "socket.io";
-import { ClientEvents, ServerEvents } from "./events";
+import { ClientEvents, ServerEvents } from "../../common/events";
 import { TodoRepository } from "./todo-management/todo.repository";
 import createTodoHandlers from "./todo-management/todo.handlers";
 

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

@@ -2,8 +2,13 @@ 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 {
+  Todo,
+  TodoID,
+  ClientEvents,
+  Response,
+  ServerEvents,
+} from "../../../common/events";
 import { Socket } from "socket.io";
 
 const idSchema = Joi.string().guid({
@@ -19,8 +24,7 @@ const todoSchema = Joi.object({
   completed: Joi.boolean().required(),
 });
 
-export default function (components: Components) {
-  const { todoRepository } = components;
+export default function ({ todoRepository }: Components) {
   return {
     createTodo: async function (
       payload: Omit<Todo, "id">,

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

@@ -1,4 +1,5 @@
 import { Errors } from "../util";
+import { Todo, TodoID } from "../../../common/events";
 
 abstract class CrudRepository<T, ID> {
   abstract findAll(): Promise<T[]>;
@@ -7,14 +8,6 @@ abstract class CrudRepository<T, ID> {
   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 {

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

@@ -24,14 +24,14 @@
     "uuid": "^8.3.2"
   },
   "devDependencies": {
-    "@types/mocha": "^8.2.3",
     "@types/chai": "^4.2.16",
+    "@types/mocha": "^10.0.0",
     "@types/uuid": "^8.3.0",
     "chai": "^4.3.4",
-    "mocha": "^8.3.2",
+    "mocha": "^10.0.0",
     "nyc": "^15.1.0",
     "socket.io-client": "^4.0.1",
-    "ts-node": "^9.1.1",
+    "ts-node": "^10.9.1",
     "typescript": "^4.2.4"
   }
 }

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

@@ -0,0 +1,23 @@
+.DS_Store
+node_modules
+/dist
+
+
+# local env files
+.env.local
+.env.*.local
+
+# Log files
+npm-debug.log*
+yarn-debug.log*
+yarn-error.log*
+pnpm-debug.log*
+
+# Editor directories and files
+.idea
+.vscode
+*.suo
+*.ntvs*
+*.njsproj
+*.sln
+*.sw?

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

@@ -0,0 +1,24 @@
+# vue-client
+
+## Project setup
+```
+yarn install
+```
+
+### Compiles and hot-reloads for development
+```
+yarn serve
+```
+
+### Compiles and minifies for production
+```
+yarn build
+```
+
+### Lints and fixes files
+```
+yarn lint
+```
+
+### Customize configuration
+See [Configuration Reference](https://cli.vuejs.org/config/).

examples/basic-crud-application/vue-client/babel.config.js

@@ -0,0 +1,5 @@
+module.exports = {
+  presets: [
+    '@vue/cli-plugin-babel/preset'
+  ]
+}

examples/basic-crud-application/vue-client/jsconfig.json

@@ -0,0 +1,19 @@
+{
+  "compilerOptions": {
+    "target": "es5",
+    "module": "esnext",
+    "baseUrl": "./",
+    "moduleResolution": "node",
+    "paths": {
+      "@/*": [
+        "src/*"
+      ]
+    },
+    "lib": [
+      "esnext",
+      "dom",
+      "dom.iterable",
+      "scripthost"
+    ]
+  }
+}

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

@@ -0,0 +1,45 @@
+{
+  "name": "vue-client",
+  "version": "0.1.0",
+  "private": true,
+  "scripts": {
+    "serve": "vue-cli-service serve --port 4200",
+    "build": "vue-cli-service build",
+    "lint": "vue-cli-service lint"
+  },
+  "dependencies": {
+    "core-js": "^3.8.3",
+    "pinia": "^2.1.7",
+    "socket.io-client": "^4.7.2",
+    "vue": "^3.2.13"
+  },
+  "devDependencies": {
+    "@babel/core": "^7.12.16",
+    "@babel/eslint-parser": "^7.12.16",
+    "@vue/cli-plugin-babel": "~5.0.0",
+    "@vue/cli-plugin-eslint": "~5.0.0",
+    "@vue/cli-service": "~5.0.0",
+    "eslint": "^7.32.0",
+    "eslint-plugin-vue": "^8.0.3"
+  },
+  "eslintConfig": {
+    "root": true,
+    "env": {
+      "node": true
+    },
+    "extends": [
+      "plugin:vue/vue3-essential",
+      "eslint:recommended"
+    ],
+    "parserOptions": {
+      "parser": "@babel/eslint-parser"
+    },
+    "rules": {}
+  },
+  "browserslist": [
+    "> 1%",
+    "last 2 versions",
+    "not dead",
+    "not ie 11"
+  ]
+}

examples/basic-crud-application/vue-client/public/index.html

@@ -0,0 +1,18 @@
+<!DOCTYPE html>
+<html lang="">
+  <head>
+    <meta charset="utf-8">
+    <meta http-equiv="X-UA-Compatible" content="IE=edge">
+    <meta name="viewport" content="width=device-width,initial-scale=1.0">
+    <link rel="icon" href="<%= BASE_URL %>favicon.ico">
+    <link href="styles.css" rel="stylesheet" type="text/css" />
+    <title><%= htmlWebpackPlugin.options.title %></title>
+  </head>
+  <body>
+    <noscript>
+      <strong>We're sorry but <%= htmlWebpackPlugin.options.title %> doesn't work properly without JavaScript enabled. Please enable it to continue.</strong>
+    </noscript>
+    <div id="app"></div>
+    <!-- built files will be auto injected -->
+  </body>
+</html>

examples/basic-crud-application/vue-client/public/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/vue-client/src/App.vue

@@ -0,0 +1,123 @@
+<script setup>
+import { computed, ref } from "vue";
+import { useTodoStore } from "@/stores/todo";
+import { socket } from "@/socket";
+
+const newTodo = ref("");
+const editedTodo = ref(undefined);
+const newTitle = ref("");
+
+const store = useTodoStore();
+
+// remove any existing listeners (in case of hot reload)
+socket.off();
+
+store.bindEvents();
+
+function addTodo() {
+  const value = newTodo.value && newTodo.value.trim();
+  if (!value) {
+    return;
+  }
+  store.add(value);
+  newTodo.value = "";
+}
+
+function editTodo(todo) {
+  editedTodo.value = todo;
+  newTitle.value = todo.title;
+}
+
+function doneEdit(todo) {
+  if (newTitle.value) {
+    store.setTitle(todo, newTitle.value);
+  } else {
+    store.delete(todo);
+  }
+  editedTodo.value = undefined;
+}
+
+function cancelEdit() {
+  editedTodo.value = undefined;
+}
+
+const allDone = computed({
+  get: () => {
+    return store.remaining === 0;
+  },
+  set: (value) => {
+    store.toggleAll(value);
+  },
+});
+
+function pluralize(word, count) {
+  return word + (count === 1 ? "" : "s");
+}
+</script>
+
+<template>
+  <section class="todoapp" v-cloak>
+    <header class="header">
+      <h1>todos</h1>
+      <input
+        class="new-todo"
+        autofocus
+        autocomplete="off"
+        placeholder="What needs to be done?"
+        v-model="newTodo"
+        @keydown.enter="addTodo"
+      />
+    </header>
+    <section class="main" v-show="store.todos.length">
+      <input
+        id="toggle-all"
+        class="toggle-all"
+        type="checkbox"
+        v-model="allDone"
+      />
+      <label for="toggle-all">Mark all as complete</label>
+      <ul class="todo-list">
+        <li
+          class="todo"
+          v-for="todo in store.todos"
+          :key="todo.id"
+          :class="{ completed: todo.completed, editing: todo === editedTodo }"
+        >
+          <div class="view">
+            <input
+              class="toggle"
+              type="checkbox"
+              v-model="todo.completed"
+              @click="store.toggleOne(todo)"
+            />
+            <label @dblclick="editTodo(todo)">{{ todo.title }}</label>
+            <button class="destroy" @click="store.delete(todo)"></button>
+          </div>
+          <input
+            class="edit"
+            type="text"
+            v-model="newTitle"
+            @blur="doneEdit"
+            @keydown.enter="doneEdit(todo)"
+            @keydown.esc="cancelEdit(todo)"
+          />
+        </li>
+      </ul>
+    </section>
+    <footer class="footer" v-show="store.todos.length">
+      <span class="todo-count">
+        <strong v-text="store.remaining"></strong>
+        {{ pluralize("item", store.remaining) }} left
+      </span>
+      <button
+        class="clear-completed"
+        @click="store.deleteCompleted"
+        v-show="store.todos.length > store.remaining"
+      >
+        Clear complete
+      </button>
+    </footer>
+  </section>
+</template>
+
+<style scoped></style>

examples/basic-crud-application/vue-client/src/main.js

@@ -0,0 +1,9 @@
+import { createApp } from "vue";
+import { createPinia } from "pinia";
+import App from "./App.vue";
+
+const pinia = createPinia();
+const app = createApp(App);
+
+app.use(pinia);
+app.mount("#app");

examples/basic-crud-application/vue-client/src/socket.js

@@ -0,0 +1,7 @@
+import { io } from "socket.io-client";
+
+// "undefined" means the URL will be computed from the `window.location` object
+const URL =
+  process.env.NODE_ENV === "production" ? undefined : "http://localhost:3000";
+
+export const socket = io(URL);

examples/basic-crud-application/vue-client/src/stores/todo.js

@@ -0,0 +1,106 @@
+import { defineStore } from "pinia";
+import { socket } from "@/socket";
+
+export const useTodoStore = defineStore("todo", {
+  state: () => ({
+    todos: [],
+  }),
+
+  getters: {
+    remaining(state) {
+      let count = 0;
+      state.todos.forEach((todo) => {
+        if (!todo.completed) {
+          count++;
+        }
+      });
+      return count;
+    },
+  },
+
+  actions: {
+    bindEvents() {
+      socket.on("connect", () => {
+        socket.emit("todo:list", (res) => {
+          this.todos = res.data;
+        });
+      });
+
+      socket.on("todo:created", (todo) => {
+        this.todos.push(todo);
+      });
+
+      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;
+        }
+      });
+
+      socket.on("todo:deleted", (id) => {
+        const i = this.todos.findIndex((t) => {
+          return t.id === id;
+        });
+        if (i !== -1) {
+          this.todos.splice(i, 1);
+        }
+      });
+    },
+
+    add(title) {
+      const todo = {
+        id: Date.now(),
+        title,
+        completed: false,
+      };
+      this.todos.push(todo);
+      socket.emit("todo:create", { title, completed: false }, (res) => {
+        todo.id = res.data;
+      });
+    },
+
+    setTitle(todo, title) {
+      todo.title = title;
+      socket.emit("todo:update", todo, () => {});
+    },
+
+    delete(todo) {
+      const i = this.todos.findIndex((t) => {
+        return t.id === todo.id;
+      });
+
+      if (i !== -1) {
+        this.todos.splice(i, 1);
+        socket.emit("todo:delete", todo.id, () => {});
+      }
+    },
+
+    deleteCompleted() {
+      this.todos.forEach((todo) => {
+        if (todo.completed) {
+          socket.emit("todo:delete", todo.id, () => {});
+        }
+      });
+
+      this.todos = this.todos.filter((t) => {
+        return !t.completed;
+      });
+    },
+
+    toggleOne(todo) {
+      todo.completed = !todo.completed;
+      socket.emit("todo:update", todo, () => {});
+    },
+
+    toggleAll(onlyActive) {
+      this.todos.forEach((todo) => {
+        if (!onlyActive || !todo.completed) {
+          this.toggleOne(todo);
+        }
+      });
+    },
+  },
+});

examples/basic-crud-application/vue-client/vue.config.js

@@ -0,0 +1,4 @@
+const { defineConfig } = require('@vue/cli-service')
+module.exports = defineConfig({
+  transpileDependencies: true
+})

examples/basic-websocket-client/README.md

@@ -0,0 +1,18 @@
+# Basic Socket.IO client
+
+Please check the associated guide: https://socket.io/how-to/build-a-basic-client
+
+Content:
+
+```
+├── bundle
+│   └── socket.io.min.js
+├── src
+│   └── index.js
+├── test
+│   └── index.js
+├── check-bundle-size.js
+├── package.json
+├── README.md
+└── rollup.config.js
+```

examples/basic-websocket-client/bundle/socket.io.min.js

@@ -0,0 +1 @@
+class e{#e=new Map;on(e,t){let s=this.#e.get(e);s||this.#e.set(e,s=[]),s.push(t)}emit(e,...t){const s=this.#e.get(e);if(s)for(const e of s)e.apply(null,t)}}const t="0",s="1",n="2",i="3",o="4",r={CONNECT:0,DISCONNECT:1,EVENT:2};function c(){}class a extends e{id;connected=!1;#t;#s;#n;#i;#o;#r=[];#c;#a=!0;constructor(e,t){super(),this.#t=e,this.#s=Object.assign({path:"/socket.io/",reconnectionDelay:2e3},t),this.#h()}#h(){this.#n=new WebSocket(this.#u()),this.#n.onmessage=({data:e})=>this.#p(e),this.#n.onerror=c,this.#n.onclose=()=>this.#l("transport close")}#u(){return`${this.#t.replace(/^http/,"ws")}${this.#s.path}?EIO=4&transport=websocket`}#p(e){if("string"==typeof e)switch(e[0]){case t:this.#d(e);break;case s:this.#l("transport close");break;case n:this.#T(),this.#m(i);break;case o:let c;try{c=function(e){let t=1;const s={type:parseInt(e.charAt(t++),10)};e.charAt(t)&&(s.data=JSON.parse(e.substring(t)));if(!function(e){switch(e.type){case r.CONNECT:return"object"==typeof e.data;case r.DISCONNECT:return void 0===e.data;case r.EVENT:{const t=e.data;return Array.isArray(t)&&t.length>0&&"string"==typeof t[0]}default:return!1}}(s))throw new Error("invalid format");return s}(e)}catch(e){return this.#l("parse error")}this.#f(c);break;default:this.#l("parse error")}}#d(e){let t;try{t=JSON.parse(e.substring(1))}catch(e){return this.#l("parse error")}this.#o=t.pingInterval+t.pingTimeout,this.#T(),this.#C()}#f(e){switch(e.type){case r.CONNECT:this.#g(e);break;case r.DISCONNECT:this.#a=!1,this.#l("io server disconnect");break;case r.EVENT:super.emit.apply(this,e.data);break;default:this.#l("parse error")}}#g(e){this.id=e.data.sid,this.connected=!0,this.#r.forEach((e=>this.#y(e))),this.#r.slice(0),super.emit("connect")}#l(e){this.#n&&(this.#n.onclose=c,this.#n.close()),clearTimeout(this.#i),clearTimeout(this.#c),this.connected?(this.connected=!1,this.id=void 0,super.emit("disconnect",e)):super.emit("connect_error",e),this.#a&&(this.#c=setTimeout((()=>this.#h()),this.#s.reconnectionDelay))}#T(){clearTimeout(this.#i),this.#i=setTimeout((()=>{this.#l("ping timeout")}),this.#o)}#m(e){this.#n.readyState===WebSocket.OPEN&&this.#n.send(e)}#y(e){this.#m(o+function(e){let t=""+e.type;e.data&&(t+=JSON.stringify(e.data));return t}(e))}#C(){this.#y({type:r.CONNECT})}emit(...e){const t={type:r.EVENT,data:e};this.connected?this.#y(t):this.#r.push(t)}disconnect(){this.#a=!1,this.#l("io client disconnect")}}function h(e,t){return"string"!=typeof e&&(t=e,e=location.origin),new a(e,t)}export{h as io};

examples/basic-websocket-client/check-bundle-size.js

@@ -0,0 +1,17 @@
+import { rollup } from "rollup";
+import terser from "@rollup/plugin-terser";
+import { brotliCompressSync } from "node:zlib";
+
+const rollupBuild = await rollup({
+  input: "./src/index.js"
+});
+
+const rollupOutput = await rollupBuild.generate({
+  format: "esm",
+  plugins: [terser()],
+});
+
+const bundleAsString = rollupOutput.output[0].code;
+const brotliedBundle = brotliCompressSync(Buffer.from(bundleAsString));
+
+console.log(`Bundle size: ${brotliedBundle.length} B`);

examples/basic-websocket-client/package.json

@@ -0,0 +1,18 @@
+{
+  "type": "module",
+  "devDependencies": {
+    "@rollup/plugin-terser": "^0.4.0",
+    "chai": "^4.3.7",
+    "mocha": "^10.2.0",
+    "prettier": "^2.8.4",
+    "rollup": "^3.20.2",
+    "socket.io": "^4.6.1",
+    "ws": "^8.13.0"
+  },
+  "scripts": {
+    "bundle": "rollup -c",
+    "check-bundle-size": "node check-bundle-size.js",
+    "format": "prettier -w src/ test/",
+    "test": "mocha"
+  }
+}

examples/basic-websocket-client/rollup.config.js

@@ -0,0 +1,10 @@
+import terser from "@rollup/plugin-terser";
+
+export default {
+  input: "./src/index.js",
+  output: {
+    file: "./bundle/socket.io.min.js",
+    format: "esm",
+    plugins: [terser()],
+  }
+};

examples/basic-websocket-client/src/index.js

@@ -0,0 +1,273 @@
+class EventEmitter {
+  #listeners = new Map();
+
+  on(event, listener) {
+    let listeners = this.#listeners.get(event);
+    if (!listeners) {
+      this.#listeners.set(event, (listeners = []));
+    }
+    listeners.push(listener);
+  }
+
+  emit(event, ...args) {
+    const listeners = this.#listeners.get(event);
+    if (listeners) {
+      for (const listener of listeners) {
+        listener.apply(null, args);
+      }
+    }
+  }
+}
+
+const EIOPacketType = {
+  OPEN: "0",
+  CLOSE: "1",
+  PING: "2",
+  PONG: "3",
+  MESSAGE: "4",
+};
+
+const SIOPacketType = {
+  CONNECT: 0,
+  DISCONNECT: 1,
+  EVENT: 2,
+};
+
+function noop() {}
+
+class Socket extends EventEmitter {
+  id;
+  connected = false;
+
+  #uri;
+  #opts;
+  #ws;
+  #pingTimeoutTimer;
+  #pingTimeoutDelay;
+  #sendBuffer = [];
+  #reconnectTimer;
+  #shouldReconnect = true;
+
+  constructor(uri, opts) {
+    super();
+    this.#uri = uri;
+    this.#opts = Object.assign(
+      {
+        path: "/socket.io/",
+        reconnectionDelay: 2000,
+      },
+      opts
+    );
+    this.#open();
+  }
+
+  #open() {
+    this.#ws = new WebSocket(this.#createUrl());
+    this.#ws.onmessage = ({ data }) => this.#onMessage(data);
+    // dummy handler for Node.js
+    this.#ws.onerror = noop;
+    this.#ws.onclose = () => this.#onClose("transport close");
+  }
+
+  #createUrl() {
+    const uri = this.#uri.replace(/^http/, "ws");
+    const queryParams = "?EIO=4&transport=websocket";
+    return `${uri}${this.#opts.path}${queryParams}`;
+  }
+
+  #onMessage(data) {
+    if (typeof data !== "string") {
+      // TODO handle binary payloads
+      return;
+    }
+
+    switch (data[0]) {
+      case EIOPacketType.OPEN:
+        this.#onOpen(data);
+        break;
+
+      case EIOPacketType.CLOSE:
+        this.#onClose("transport close");
+        break;
+
+      case EIOPacketType.PING:
+        this.#resetPingTimeout();
+        this.#send(EIOPacketType.PONG);
+        break;
+
+      case EIOPacketType.MESSAGE:
+        let packet;
+        try {
+          packet = decode(data);
+        } catch (e) {
+          return this.#onClose("parse error");
+        }
+        this.#onPacket(packet);
+        break;
+
+      default:
+        this.#onClose("parse error");
+        break;
+    }
+  }
+
+  #onOpen(data) {
+    let handshake;
+    try {
+      handshake = JSON.parse(data.substring(1));
+    } catch (e) {
+      return this.#onClose("parse error");
+    }
+    this.#pingTimeoutDelay = handshake.pingInterval + handshake.pingTimeout;
+    this.#resetPingTimeout();
+    this.#doConnect();
+  }
+
+  #onPacket(packet) {
+    switch (packet.type) {
+      case SIOPacketType.CONNECT:
+        this.#onConnect(packet);
+        break;
+
+      case SIOPacketType.DISCONNECT:
+        this.#shouldReconnect = false;
+        this.#onClose("io server disconnect");
+        break;
+
+      case SIOPacketType.EVENT:
+        super.emit.apply(this, packet.data);
+        break;
+
+      default:
+        this.#onClose("parse error");
+        break;
+    }
+  }
+
+  #onConnect(packet) {
+    this.id = packet.data.sid;
+    this.connected = true;
+
+    this.#sendBuffer.forEach((packet) => this.#sendPacket(packet));
+    this.#sendBuffer.slice(0);
+
+    super.emit("connect");
+  }
+
+  #onClose(reason) {
+    if (this.#ws) {
+      this.#ws.onclose = noop;
+      this.#ws.close();
+    }
+
+    clearTimeout(this.#pingTimeoutTimer);
+    clearTimeout(this.#reconnectTimer);
+
+    if (this.connected) {
+      this.connected = false;
+      this.id = undefined;
+      super.emit("disconnect", reason);
+    } else {
+      super.emit("connect_error", reason);
+    }
+
+    if (this.#shouldReconnect) {
+      this.#reconnectTimer = setTimeout(
+        () => this.#open(),
+        this.#opts.reconnectionDelay
+      );
+    }
+  }
+
+  #resetPingTimeout() {
+    clearTimeout(this.#pingTimeoutTimer);
+    this.#pingTimeoutTimer = setTimeout(() => {
+      this.#onClose("ping timeout");
+    }, this.#pingTimeoutDelay);
+  }
+
+  #send(data) {
+    if (this.#ws.readyState === WebSocket.OPEN) {
+      this.#ws.send(data);
+    }
+  }
+
+  #sendPacket(packet) {
+    this.#send(EIOPacketType.MESSAGE + encode(packet));
+  }
+
+  #doConnect() {
+    this.#sendPacket({ type: SIOPacketType.CONNECT });
+  }
+
+  emit(...args) {
+    const packet = {
+      type: SIOPacketType.EVENT,
+      data: args,
+    };
+
+    if (this.connected) {
+      this.#sendPacket(packet);
+    } else {
+      this.#sendBuffer.push(packet);
+    }
+  }
+
+  disconnect() {
+    this.#shouldReconnect = false;
+    this.#onClose("io client disconnect");
+  }
+}
+
+function encode(packet) {
+  let output = "" + packet.type;
+
+  if (packet.data) {
+    output += JSON.stringify(packet.data);
+  }
+
+  return output;
+}
+
+function decode(data) {
+  let i = 1; // skip "4" prefix
+
+  const packet = {
+    type: parseInt(data.charAt(i++), 10),
+  };
+
+  if (data.charAt(i)) {
+    packet.data = JSON.parse(data.substring(i));
+  }
+
+  if (!isPacketValid(packet)) {
+    throw new Error("invalid format");
+  }
+
+  return packet;
+}
+
+function isPacketValid(packet) {
+  switch (packet.type) {
+    case SIOPacketType.CONNECT:
+      return typeof packet.data === "object";
+    case SIOPacketType.DISCONNECT:
+      return packet.data === undefined;
+    case SIOPacketType.EVENT: {
+      const args = packet.data;
+      return (
+        Array.isArray(args) && args.length > 0 && typeof args[0] === "string"
+      );
+    }
+    default:
+      return false;
+  }
+}
+
+export function io(uri, opts) {
+  if (typeof uri !== "string") {
+    opts = uri;
+    uri = location.origin;
+  }
+  return new Socket(uri, opts);
+}

examples/basic-websocket-client/test/index.js

@@ -0,0 +1,162 @@
+import { createServer } from "node:http";
+import { io as ioc } from "../src/index.js";
+import { WebSocket } from "ws";
+import { Server } from "socket.io";
+import { expect } from "chai";
+
+// @ts-ignore for Node.js
+globalThis.WebSocket = WebSocket;
+
+function waitFor(emitter, eventName) {
+  return new Promise((resolve) => {
+    emitter.on(eventName, resolve);
+  });
+}
+
+function sleep(delay) {
+  return new Promise((resolve) => {
+    setTimeout(resolve, delay);
+  });
+}
+
+describe("basic client", () => {
+  let io, port, socket;
+
+  beforeEach(() => {
+    const httpServer = createServer();
+    io = new Server(httpServer);
+
+    httpServer.listen(0);
+    port = httpServer.address().port;
+  });
+
+  afterEach(() => {
+    io.close();
+    socket.disconnect();
+  });
+
+  it("should connect", async () => {
+    socket = ioc(`ws://localhost:${port}`);
+
+    await waitFor(socket, "connect");
+
+    expect(socket.connected).to.eql(true);
+    expect(socket.id).to.be.a("string");
+  });
+
+  it("should connect with 'http://' scheme", async () => {
+    socket = ioc(`http://localhost:${port}`);
+
+    await waitFor(socket, "connect");
+  });
+
+  it("should connect with URL inferred from 'window.location'", async () => {
+    globalThis.location = {
+      origin: `http://localhost:${port}`,
+    };
+    socket = ioc();
+
+    await waitFor(socket, "connect");
+  });
+
+  it("should fail to connect to an invalid URL", async () => {
+    socket = ioc(`http://localhost:4321`);
+
+    await waitFor(socket, "connect_error");
+  });
+
+  it("should receive an event", async () => {
+    io.on("connection", (socket) => {
+      socket.emit("foo", 123);
+    });
+
+    socket = ioc(`ws://localhost:${port}`);
+
+    const value = await waitFor(socket, "foo");
+
+    expect(value).to.eql(123);
+  });
+
+  it("should send an event (not buffered)", async () => {
+    socket = ioc(`ws://localhost:${port}`);
+
+    const [serverSocket] = await Promise.all([
+      waitFor(io, "connection"),
+      waitFor(socket, "connect"),
+    ]);
+
+    socket.emit("foo", 456);
+
+    const value = await waitFor(serverSocket, "foo");
+
+    expect(value).to.eql(456);
+  });
+
+  it("should send an event (buffered)", async () => {
+    socket = ioc(`ws://localhost:${port}`);
+
+    socket.emit("foo", 789);
+
+    const [serverSocket] = await Promise.all([
+      waitFor(io, "connection"),
+      waitFor(socket, "connect"),
+    ]);
+
+    const value = await waitFor(serverSocket, "foo");
+
+    expect(value).to.eql(789);
+  });
+
+  it("should reconnect", async () => {
+    socket = ioc(`ws://localhost:${port}`, {
+      reconnectionDelay: 50,
+    });
+
+    await waitFor(socket, "connect");
+
+    io.close();
+
+    await waitFor(socket, "disconnect");
+
+    io.listen(port);
+
+    await waitFor(socket, "connect");
+  });
+
+  it("should respond to PING packets", async () => {
+    io.engine.opts.pingInterval = 50;
+    io.engine.opts.pingTimeout = 20;
+
+    socket = ioc(`ws://localhost:${port}`);
+
+    await waitFor(socket, "connect");
+
+    await sleep(500);
+
+    expect(socket.connected).to.eql(true);
+  });
+
+  it("should disconnect (client side)", async () => {
+    socket = ioc(`ws://localhost:${port}`);
+
+    await waitFor(socket, "connect");
+
+    socket.disconnect();
+
+    expect(socket.connected).to.eql(false);
+    expect(socket.id).to.eql(undefined);
+  });
+
+  it("should disconnect (server side)", async () => {
+    socket = ioc(`ws://localhost:${port}`);
+
+    const [serverSocket] = await Promise.all([
+      waitFor(io, "connection"),
+      waitFor(socket, "connect"),
+    ]);
+
+    serverSocket.disconnect();
+
+    await waitFor(socket, "disconnect");
+  });
+});

examples/cluster-haproxy/docker-compose.yml

@@ -1,51 +1,53 @@
+services:
+  haproxy:
+    image: haproxy:1.7-alpine
+    volumes:
+      - ./haproxy.cfg:/usr/local/etc/haproxy/haproxy.cfg:ro
+    links:
+      - server-john
+      - server-paul
+      - server-george
+      - server-ringo
+    ports:
+     - "3000:80"
 
-haproxy:
-  build: ./haproxy
-  links:
-    - server-john
-    - server-paul
-    - server-george
-    - server-ringo
-  ports:
-   - "3000:80"
+  server-john:
+    build: ./server
+    links:
+      - redis
+    expose:
+      - "3000"
+    environment:
+      - NAME=John
 
-server-john:
-  build: ./server
-  links:
-    - redis
-  expose:
-    - "3000"
-  environment:
-    - NAME=John
+  server-paul:
+    build: ./server
+    links:
+      - redis
+    expose:
+      - "3000"
+    environment:
+      - NAME=Paul
 
-server-paul:
-  build: ./server
-  links:
-    - redis
-  expose:
-    - "3000"
-  environment:
-    - NAME=Paul
+  server-george:
+    build: ./server
+    links:
+      - redis
+    expose:
+      - "3000"
+    environment:
+      - NAME=George
 
-server-george:
-  build: ./server
-  links:
-    - redis
-  expose:
-    - "3000"
-  environment:
-    - NAME=George
+  server-ringo:
+    build: ./server
+    links:
+      - redis
+    expose:
+      - "3000"
+    environment:
+      - NAME=Ringo
 
-server-ringo:
-  build: ./server
-  links:
-    - redis
-  expose:
-    - "3000"
-  environment:
-    - NAME=Ringo
-
-redis:
-  image: redis:alpine
-  expose:
-    - "6379"
+  redis:
+    image: redis:alpine
+    expose:
+      - "6379"

examples/cluster-haproxy/haproxy/Dockerfile

@@ -1,2 +0,0 @@
-FROM haproxy:1.7-alpine
-COPY haproxy.cfg /usr/local/etc/haproxy/haproxy.cfg

examples/cluster-httpd/docker-compose.yml

@@ -1,51 +1,53 @@
+services:
+  httpd:
+    image: httpd:2.4-alpine
+    volumes:
+      - ./httpd.conf:/usr/local/apache2/conf/httpd.conf:ro
+    links:
+      - server-john
+      - server-paul
+      - server-george
+      - server-ringo
+    ports:
+     - "3000:80"
 
-httpd:
-  build: ./httpd
-  links:
-    - server-john
-    - server-paul
-    - server-george
-    - server-ringo
-  ports:
-   - "3000:80"
+  server-john:
+    build: ./server
+    links:
+      - redis
+    expose:
+      - "3000"
+    environment:
+      - NAME=John
 
-server-john:
-  build: ./server
-  links:
-    - redis
-  expose:
-    - "3000"
-  environment:
-    - NAME=John
+  server-paul:
+    build: ./server
+    links:
+      - redis
+    expose:
+      - "3000"
+    environment:
+      - NAME=Paul
 
-server-paul:
-  build: ./server
-  links:
-    - redis
-  expose:
-    - "3000"
-  environment:
-    - NAME=Paul
+  server-george:
+    build: ./server
+    links:
+      - redis
+    expose:
+      - "3000"
+    environment:
+      - NAME=George
 
-server-george:
-  build: ./server
-  links:
-    - redis
-  expose:
-    - "3000"
-  environment:
-    - NAME=George
+  server-ringo:
+    build: ./server
+    links:
+      - redis
+    expose:
+      - "3000"
+    environment:
+      - NAME=Ringo
 
-server-ringo:
-  build: ./server
-  links:
-    - redis
-  expose:
-    - "3000"
-  environment:
-    - NAME=Ringo
-
-redis:
-  image: redis:alpine
-  expose:
-    - "6379"
+  redis:
+    image: redis:6
+    expose:
+      - "6379"

examples/cluster-httpd/httpd.conf

@@ -51,4 +51,5 @@ RewriteRule /(.*) balancer://nodes_ws/$1 [P,L]
 RewriteCond %{HTTP:Upgrade} !=websocket [NC]
 RewriteRule /(.*) balancer://nodes_polling/$1 [P,L]
 
-ProxyTimeout 3
+# must be bigger than pingInterval (25s by default) + pingTimeout (20s by default)
+ProxyTimeout 60

examples/cluster-httpd/httpd/Dockerfile

@@ -1,2 +0,0 @@
-FROM httpd:2.4-alpine
-COPY ./httpd.conf /usr/local/apache2/conf/httpd.conf

examples/cluster-httpd/server/Dockerfile

@@ -1,4 +1,4 @@
-FROM mhart/alpine-node:6
+FROM node:14-alpine
 
 # Create app directory
 RUN mkdir -p /usr/src/app

examples/cluster-nginx/docker-compose.yml

@@ -3,18 +3,27 @@ services:
     image: nginx:alpine
     volumes:
       - ./nginx.conf:/etc/nginx/nginx.conf:ro
+    links:
+      - server-john
+      - server-paul
+      - server-george
+      - server-ringo
     ports:
-    - "3000:80"
+     - "3000:80"
 
   server-john:
     build: ./server
+    links:
+      - redis
     expose:
-    - "3000"
+      - "3000"
     environment:
       - NAME=John
 
   server-paul:
     build: ./server
+    links:
+      - redis
     expose:
       - "3000"
     environment:
@@ -22,6 +31,8 @@ services:
 
   server-george:
     build: ./server
+    links:
+      - redis
     expose:
       - "3000"
     environment:
@@ -29,6 +40,8 @@ services:
 
   server-ringo:
     build: ./server
+    links:
+      - redis
     expose:
       - "3000"
     environment:
@@ -36,8 +49,10 @@ services:
 
   client:
     build: ./client
+    links:
+      - nginx
 
   redis:
-    image: redis:alpine
+    image: redis:6
     expose:
       - "6379"

examples/connection-state-recovery-example/README.md

@@ -0,0 +1,25 @@
+# Example with connection state recovery
+
+This example shows how to use the [Connection state recovery feature](https://socket.io/docs/v4/connection-state-recovery).
+
+![Video of the example](assets/csr.gif)
+
+## How to use
+
+```shell
+# choose your module syntax (either ES modules or CommonJS)
+$ cd esm/
+
+# install the dependencies
+$ npm i
+
+# start the server
+$ node index.js
+```
+
+And point your browser to `http://localhost:3000`.
+
+You can also run this example directly in your browser on:
+
+- [CodeSandbox](https://codesandbox.io/p/sandbox/github/socketio/socket.io/tree/main/examples/connection-state-recovery-example/esm?file=index.js)
+- [StackBlitz](https://stackblitz.com/github/socketio/socket.io/tree/main/examples/connection-state-recovery-example/esm?file=index.js)

examples/connection-state-recovery-example/cjs/.codesandbox/Dockerfile

@@ -0,0 +1 @@
+FROM node:20-bullseye

examples/connection-state-recovery-example/cjs/.codesandbox/tasks.json

@@ -0,0 +1,18 @@
+{
+  // These tasks will run in order when initializing your CodeSandbox project.
+  "setupTasks": [
+    {
+      "name": "Install Dependencies",
+      "command": "npm install"
+    }
+  ],
+
+  // These tasks can be run from CodeSandbox. Running one will open a log in the app.
+  "tasks": {
+    "npm start": {
+      "name": "npm start",
+      "command": "npm start",
+      "runAtStart": true
+    }
+  }
+}

examples/connection-state-recovery-example/cjs/index.html

@@ -0,0 +1,49 @@
+<!DOCTYPE html>
+<html lang="en">
+  <head>
+    <meta charset="UTF-8" />
+    <title>Connection state recovery | Socket.IO</title>
+  </head>
+  <body>
+    <p>Status: <span id="connectionStatus">disconnected</span></p>
+    <p>Recovered? <span id="recoveryStatus">-</span></p>
+
+    <p>Latest messages:</p>
+    <ul id="messages"></ul>
+
+    <script src="/socket.io/socket.io.js"></script>
+    <script>
+      const $connectionStatus = document.getElementById("connectionStatus");
+      const $recoveryStatus = document.getElementById("recoveryStatus");
+      const $messages = document.getElementById("messages");
+
+      const socket = io({
+        reconnectionDelay: 5000 // 1000 by default
+      });
+
+      socket.on("connect", () => {
+        $connectionStatus.innerText = "connected";
+        $recoveryStatus.innerText = "" + socket.recovered;
+
+        setTimeout(() => {
+          // close the low-level connection and trigger a reconnection
+          socket.io.engine.close();
+        }, Math.random() * 5000 + 1000);
+      });
+
+      socket.on("disconnect", () => {
+        $connectionStatus.innerText = "disconnected";
+        $recoveryStatus.innerText = "-"
+      });
+
+      socket.on("ping", (value) => {
+        const item = document.createElement("li");
+        item.textContent = value;
+        $messages.prepend(item);
+        if ($messages.childElementCount > 10) {
+          $messages.removeChild($messages.lastChild);
+        }
+      });
+    </script>
+  </body>
+</html>

examples/connection-state-recovery-example/cjs/index.js

@@ -0,0 +1,53 @@
+const { readFile } = require("node:fs/promises");
+const { createServer } = require("node:http");
+const { Server } = require("socket.io");
+
+const httpServer = createServer(async (req, res) => {
+  if (req.url !== "/") {
+    res.writeHead(404);
+    res.end("Not found");
+    return;
+  }
+  // reload the file every time
+  const content = await readFile("index.html");
+  const length = Buffer.byteLength(content);
+
+  res.writeHead(200, {
+    "Content-Type": "text/html",
+    "Content-Length": length,
+  });
+  res.end(content);
+});
+
+const io = new Server(httpServer, {
+  connectionStateRecovery: {
+    // the backup duration of the sessions and the packets
+    maxDisconnectionDuration: 2 * 60 * 1000,
+    // whether to skip middlewares upon successful recovery
+    skipMiddlewares: true,
+  },
+});
+
+io.on("connection", (socket) => {
+  console.log(`connect ${socket.id}`);
+
+  if (socket.recovered) {
+    console.log("recovered!");
+    console.log("socket.rooms:", socket.rooms);
+    console.log("socket.data:", socket.data);
+  } else {
+    console.log("new connection");
+    socket.join("sample room");
+    socket.data.foo = "bar";
+  }
+
+  socket.on("disconnect", (reason) => {
+    console.log(`disconnect ${socket.id} due to ${reason}`);
+  });
+});
+
+setInterval(() => {
+  io.emit("ping", new Date().toISOString());
+}, 1000);
+
+httpServer.listen(3000);

examples/connection-state-recovery-example/cjs/package.json

@@ -0,0 +1,13 @@
+{
+  "name": "connection-state-recovery-example",
+  "version": "0.0.1",
+  "private": true,
+  "type": "commonjs",
+  "description": "Example with connection state recovery",
+  "scripts": {
+    "start": "node index.js"
+  },
+  "dependencies": {
+    "socket.io": "^4.7.2"
+  }
+}

examples/connection-state-recovery-example/esm/.codesandbox/Dockerfile

@@ -0,0 +1 @@
+FROM node:20-bullseye

examples/connection-state-recovery-example/esm/.codesandbox/tasks.json

@@ -0,0 +1,18 @@
+{
+  // These tasks will run in order when initializing your CodeSandbox project.
+  "setupTasks": [
+    {
+      "name": "Install Dependencies",
+      "command": "npm install"
+    }
+  ],
+
+  // These tasks can be run from CodeSandbox. Running one will open a log in the app.
+  "tasks": {
+    "npm start": {
+      "name": "npm start",
+      "command": "npm start",
+      "runAtStart": true
+    }
+  }
+}

examples/connection-state-recovery-example/esm/index.html

@@ -0,0 +1,49 @@
+<!DOCTYPE html>
+<html lang="en">
+  <head>
+    <meta charset="UTF-8" />
+    <title>Connection state recovery | Socket.IO</title>
+  </head>
+  <body>
+    <p>Status: <span id="connectionStatus">disconnected</span></p>
+    <p>Recovered? <span id="recoveryStatus">-</span></p>
+
+    <p>Latest messages:</p>
+    <ul id="messages"></ul>
+
+    <script src="/socket.io/socket.io.js"></script>
+    <script>
+      const $connectionStatus = document.getElementById("connectionStatus");
+      const $recoveryStatus = document.getElementById("recoveryStatus");
+      const $messages = document.getElementById("messages");
+
+      const socket = io({
+        reconnectionDelay: 5000 // 1000 by default
+      });
+
+      socket.on("connect", () => {
+        $connectionStatus.innerText = "connected";
+        $recoveryStatus.innerText = "" + socket.recovered;
+
+        setTimeout(() => {
+          // close the low-level connection and trigger a reconnection
+          socket.io.engine.close();
+        }, Math.random() * 5000 + 1000);
+      });
+
+      socket.on("disconnect", () => {
+        $connectionStatus.innerText = "disconnected";
+        $recoveryStatus.innerText = "-"
+      });
+
+      socket.on("ping", (value) => {
+        const item = document.createElement("li");
+        item.textContent = value;
+        $messages.prepend(item);
+        if ($messages.childElementCount > 10) {
+          $messages.removeChild($messages.lastChild);
+        }
+      });
+    </script>
+  </body>
+</html>

examples/connection-state-recovery-example/esm/index.js

@@ -0,0 +1,53 @@
+import { readFile } from "node:fs/promises";
+import { createServer } from "node:http";
+import { Server } from "socket.io";
+
+const httpServer = createServer(async (req, res) => {
+  if (req.url !== "/") {
+    res.writeHead(404);
+    res.end("Not found");
+    return;
+  }
+  // reload the file every time
+  const content = await readFile("index.html");
+  const length = Buffer.byteLength(content);
+
+  res.writeHead(200, {
+    "Content-Type": "text/html",
+    "Content-Length": length,
+  });
+  res.end(content);
+});
+
+const io = new Server(httpServer, {
+  connectionStateRecovery: {
+    // the backup duration of the sessions and the packets
+    maxDisconnectionDuration: 2 * 60 * 1000,
+    // whether to skip middlewares upon successful recovery
+    skipMiddlewares: true,
+  },
+});
+
+io.on("connection", (socket) => {
+  console.log(`connect ${socket.id}`);
+
+  if (socket.recovered) {
+    console.log("recovered!");
+    console.log("socket.rooms:", socket.rooms);
+    console.log("socket.data:", socket.data);
+  } else {
+    console.log("new connection");
+    socket.join("sample room");
+    socket.data.foo = "bar";
+  }
+
+  socket.on("disconnect", (reason) => {
+    console.log(`disconnect ${socket.id} due to ${reason}`);
+  });
+});
+
+setInterval(() => {
+  io.emit("ping", new Date().toISOString());
+}, 1000);
+
+httpServer.listen(3000);

examples/connection-state-recovery-example/esm/package.json

@@ -0,0 +1,13 @@
+{
+  "name": "connection-state-recovery-example",
+  "version": "0.0.1",
+  "private": true,
+  "type": "module",
+  "description": "Example with connection state recovery",
+  "scripts": {
+    "start": "node index.js"
+  },
+  "dependencies": {
+    "socket.io": "^4.7.2"
+  }
+}