A package of Ts.ED framework. See website: https://tsed.dev/tutorials/socket-io

Socket.io enable real-time bidirectional event-based communication. It works on every platform, browser or device, focusing equally on reliability and speed.

Installation

Before using the Socket.io, we need to install the Socket.io module.

npm install --save socket.io @types/socket.io @tsed/socketio

Then add the following configuration in your Server:

import {Configuration} from "@tsed/di";
import "@tsed/socketio"; // import socketio Ts.ED module
import {resolve} from "node:path";

@Configuration({
  socketIO: {
    // ... see configuration
  }
})
export class Server {}

Socket Service

Socket.IO allows you to “namespace” your sockets, which essentially means assigning different endpoints or paths. This is a useful feature to minimize the number of resources (TCP connections) and at the same time separate concerns within your application by introducing separation between communication channels. See namespace documentation.

All Socket service work under a namespace and you can create one Socket service per namespace.

Example:

import * as SocketIO from "socket.io";
import {SocketService, IO, Nsp, Socket, SocketSession, Reason} from "@tsed/socketio";

@SocketService("/my-namespace")
export class MySocketService {
  @Nsp nsp: SocketIO.Namespace;

  @Nsp("/my-other-namespace")
  nspOther: SocketIO.Namespace; // communication between two namespace

  constructor(@IO private io: SocketIO.Server) {}

  /**
   * Triggered the namespace is created
   */
  $onNamespaceInit(nsp: SocketIO.Namespace) {}

  /**
   * Triggered when a new client connects to the Namespace.
   */
  $onConnection(@Socket socket: SocketIO.Socket, @SocketSession session: SocketSession) {}

  /**
   * Triggered when a client disconnects from the Namespace.
   */
  $onDisconnect(@Socket socket: SocketIO.Socket, @Reason reason: string) {}
}

@SocketService inherit from @Service decorator. That means, a SocketService can be injected to another Service, Controller or Middleware.

Example:

import * as SocketIO from "socket.io";
import {SocketService, Nsp} from "@tsed/socketio";

@SocketService()
export class MySocketService {
  @Nsp nsp: SocketIO.Namespace;

  helloAll() {
    this.nsp.emit("hi", "everyone!");
  }
}

Then, you can inject your socket service into another Service, Controller, etc... as following:

import {Controller} from "@tsed/di";
import {Get} from "@tsed/schema";
import {MySocketService} from "../services/MySocketService.js";

@Controller("/")
export class MyCtrl {
  constructor(private mySocketService: MySocketService) {}

  @Get("/allo")
  allo() {
    this.mySocketService.helloAll();
    return "is sent";
  }
}

Declaring an Input Event

@Input decorator declare a method as a new handler for a specific event.

import {SocketService, Input, Emit, Args, Socket, Nsp} from "@tsed/socketio";

@SocketService("/my-namespace")
export class MySocketService {
  @Input("eventName")
  myMethod(@Args(0) userName: string, @Socket socket: SocketIO.Socket, @Nsp nsp: SocketIO.Namespace) {
    console.log(userName);
  }
}

• @Args <any|any[]>: List of the parameters sent by the input event.
• @Socket <SocketIO.Socket>: Socket instance.
• @Nsp <SocketIO.Namespace>: Namespace instance.

Send a response

You have a many choice to send a response to your client. Ts.ED offer some decorators to send a response:

Example:

import {SocketService, Input, Emit, Args, Socket, Nsp} from "@tsed/socketio";

@SocketService("/my-namespace")
export class MySocketService {
  @Input("eventName")
  @Emit("responseEventName") // or Broadcast or BroadcastOthers
  async myMethod(@Args(0) userName: string, @Socket socket: SocketIO.Socket) {
    return "Message " + userName;
  }
}

The method accept a promise as returned value.

::: warning Return value is only possible when the method is decorated by @Emit, @Broadcast and @BroadcastOthers. :::

Socket Session

Ts.ED create a new session for each socket.

import {SocketService, Input, Emit, Args, SocketSession} from "@tsed/socketio";

@SocketService("/my-namespace")
export class MySocketService {
  @Input("eventName")
  @Emit("responseEventName") // or Broadcast or BroadcastOthers
  async myMethod(@Args(0) userName: string, @SocketSession session: SocketSession) {
    const user = session.get("user") || {};
    user.name = userName;

    session.set("user", user);

    return user;
  }
}

The session represents an arbitrary object that facilitates the storage of session data, allowing the sharing of information between Socket.IO servers.

In the event of an unexpected disconnection (i.e., when the socket is not manually disconnected using socket.disconnect()), the server will store the session of the socket. Upon reconnection, the server will make an attempt to restore the previous session.

To enable this behavior, you need to configure the Connection state recovery as follows:

import {Configuration} from "@tsed/di";
import "@tsed/platform-express";
import "@tsed/socketio";

@Configuration({
  socketIO: {
    // ... see configuration
    connectionStateRecovery: {
      // the backup duration of the sessions and the packets
      maxDisconnectionDuration: 2 * 60 * 1000,
      // whether to skip middlewares upon successful recovery
      skipMiddlewares: true
    }
  }
})
export class Server {}

By default, Ts.ED uses the built-in in-memory adapter for session management. However, for production environments, it is recommended to use the persistent adapters to enhance reliability.

Middlewares

A middleware can be also used on a SocketService either on a class or on a method.

Here an example of a middleware:

import {deserialize} from "@tsed/json-mapper";
import {SocketMiddleware, Args} from "@tsed/socketio";
import {User} from "../models/User.js";

@SocketMiddleware()
export class UserConverterSocketMiddleware {
  async use(@Args() args: any[]) {
    let [user] = args;
    // update Arguments
    user = deserialize(user, {type: User});

    return [user];
  }
}

The user instance will be forwarded to the next middleware and to your decorated method.

You can also declare a middleware to handle an error with @SocketMiddlewareError. Here an example:

import {SocketMiddlewareError, SocketErr, Socket} from "@tsed/socketio";

@SocketMiddlewareError()
export class ErrorHandlerSocketMiddleware {
  async use(@SocketErr err: any, @Socket socket: SocketIO.Socket) {
    console.error(err);
    socket.emit("error", {message: "An error has occured"});
  }
}

Then, two decorators are provided to attach your middleware on the right place:

• @SocketUseBefore will call your middleware before the class method,
• @SocketUseAfter will call your middleware after the class method.

Both decorators can be used as a class decorator or as a method decorator. The call sequences is the following for each event request:

• Middlewares attached with @SocketUseBefore on class,
• Middlewares attached with @SocketUseBefore on method,
• The method,
• Send response if the method is decorated with @Emit, @Broadcast or @BroadcastOther,
• Middlewares attached with @SocketUseAfter on method,
• Middlewares attached with @SocketUseAfter on class.

Middlewares chain use the Promise to run it. If one of this middlewares/method emit an error, the first middleware error will be called.

import {SocketService, SocketUseAfter, SocketUseBefore, Emit, Input, Args, SocketSession} from "@tsed/socketio";
import {UserConverterSocketMiddleware, ErrorHandlerSocketMiddleware} from "../middlewares.js";
import {User} from "../models/User.js";
import {SocketSessionData} from "@tsed/socketio/lib/cjs";

@SocketService("/my-namespace")
@SocketUseBefore(UserConverterSocketMiddleware) // global version
@SocketUseAfter(ErrorHandlerSocketMiddleware)
export class MySocketService {
  @Input("eventName")
  @Emit("responseEventName") // or Broadcast or BroadcastOthers
  @SocketUseBefore(UserConverterSocketMiddleware)
  @SocketUseAfter(ErrorHandlerSocketMiddleware)
  async myMethod(@Args(0) userName: User, @SocketSessionData session: SocketSessionData) {
    const user = session.get("user") || {};
    user.name = userName;

    session.set("user", user);

    return user;
  }
}

Documentation

See our documentation https://tsed.dev/api.html

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License

The MIT License (MIT)

Copyright (c) 2016 - 2022 Romain Lenzotti

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.