SocketZone.com Internet Socket | Websocket Information Blog
Websockets are a powerful tool for real-time communication between the client and the server. In Angular 9, you can easily implement websockets using the Websocket API. This tutorial will guide you through the process of setting up websockets in your Angular 9 application, with a detailed example.
What is a Websocket?
A websocket is a bi-directional communication protocol that allows the client and the server to exchange data in real-time. Unlike traditional HTTP requests, websockets keep the connection open between the client and the server, enabling real-time communication.
Why Use Websockets in Your Angular Application?
Websockets are useful for real-time applications that require frequent communication between the client and the server. This includes chat applications, real-time games, stock tickers, and more. By using websockets, you can reduce the latency and improve the performance of your application.
Setting Up a Websocket in Your Angular 9 Application
Step 1: Install the WebSocket API
The first step in setting up a websocket in your Angular 9 application is to install the WebSocket API. You can do this by running the following command in your terminal:
npm install --save @types/websocket
This will install the latest version of the WebSocket API and its types. You will use the WebSocket API to create and manage the websocket connection in your Angular application.
Step 2: Create a Websocket Service
The next step is to create a service that will handle the websocket connection. You can do this by running the following command in your terminal:
ng generate service websocket
This will create a new service called “websocket” in your Angular application. You can then open the “websocket.service.ts” file and add the following code:
import { Injectable } from '@angular/core';import * as WebSocket from 'websocket';@Injectable({providedIn: 'root'})export class WebsocketService {private socket: WebSocket;
constructor() { }
public connect(): void {this.socket = new WebSocket('ws://localhost:8080');
this.socket.onopen = () => {console.log('Connected to websocket server');};
this.socket.onclose = () => {console.log('Disconnected from websocket server');};
this.socket.onerror = (error) => {console.log('Websocket error:', error);};
this.socket.onmessage = (message) => {console.log('Received message:', message);};}
public send(message: string): void {this.socket.send(message);}}
This code creates a new WebSocket object and sets up event listeners for when the connection is opened, closed, or there is an error. It also sets up a listener for incoming messages. Finally, it defines a method for sending messages over the websocket connection.
Step 3: Connect to the Websocket Server
The final step is to connect to the websocket server. You can do this by calling the “connect” method in the “websocket” service. You can do this in the “ngOnInit” method of any component that needs to use the websocket connection.
import { Component, OnInit } from '@angular/core';import { WebsocketService } from './websocket.service';@Component({selector: 'app-root',templateUrl: './app.component.html',styleUrls: ['./app.component.css']})export class AppComponent implements OnInit {constructor(private websocketService: WebsocketService) { }
ngOnInit() {this.websocketService.connect();}}
Now that you have set up the websocket connection in your Angular 9 application, you can start sending and receiving messages over the connection.
Example: Sending and Receiving Messages over a Websocket Connection
Now that you have set up the websocket connection in your Angular 9 application, let’s look at an example of sending and receiving messages over the connection.
Step 1: Create a Websocket Server
The first step is to create a websocket server that will receive messages from the client. You can do this using any server-side language that supports websockets, such as Node.js or Python. Here is an example of a Node.js websocket server:
const WebSocket = require('ws');const server = new WebSocket.Server({ port: 8080 });
server.on('connection', (socket) => {console.log('Client connected');
socket.on('message', (message) => {console.log('Received message:', message);
// Echo the message back to the clientsocket.send(message);});
socket.on('close', () => {console.log('Client disconnected');});});
This code creates a new websocket server that listens on port 8080. It sets up event listeners for when a client connects, sends a message, or disconnects. When a message is received, it echoes the message back to the client.
Step 2: Send a Message over the Websocket Connection
The next step is to send a message over the websocket connection from the client to the server. You can do this by calling the “send” method in the “websocket” service. Here is an example:
import { Component, OnInit } from '@angular/core';import { WebsocketService } from './websocket.service';@Component({selector: 'app-root',templateUrl: './app.component.html',styleUrls: ['./app.component.css']})export class AppComponent implements OnInit {constructor(private websocketService: WebsocketService) { }
ngOnInit() {this.websocketService.connect();}
sendMessage() {this.websocketService.send('Hello, server!');}}
This code calls the “send” method in the “websocket” service, passing in the message “Hello, server!”. This sends the message over the websocket connection to the server.
Step 3: Receive a Message over the Websocket Connection
The final step is to receive a message over the websocket connection from the server. You can do this by setting up an event listener for incoming messages in the “websocket” service. Here is an example:
import { Injectable } from '@angular/core';import * as WebSocket from 'websocket';@Injectable({providedIn: 'root'})export class WebsocketService {private socket: WebSocket;public messages: string[] = [];
constructor() { }
public connect(): void {this.socket = new WebSocket('ws://localhost:8080');
this.socket.onopen = () => {console.log('Connected to websocket server');};
this.socket.onclose = () => {console.log('Disconnected from websocket server');};
this.socket.onerror = (error) => {console.log('Websocket error:', error);};
this.socket.onmessage = (message) => {console.log('Received message:', message);this.messages.push(message.data);};}
public send(message: string): void {this.socket.send(message);}}
This code sets up an array to store incoming messages. It also adds a listener for incoming messages that appends the message to the array. You can then display the messages in your Angular template:
<ul><li *ngFor="let message of websocketService.messages">{{ message }}</li></ul>Now when you send a message over the websocket connection, it will be received by the server and echoed back to the client. The client will then display the message in a list on the page.
Frequently Asked Questions
What is the difference between WebSockets and HTTP?
HTTP is a request-response protocol, meaning that the client sends a request to the server and the server sends a response back to the client. WebSockets, on the other hand, keep the connection open between the client and the server, allowing for real-time communication.
What are some use cases for WebSockets?
WebSockets are useful for real-time applications that require frequent communication between the client and the server. This includes chat applications, real-time games, stock tickers, and more.
What are the advantages of using WebSockets?
WebSockets can reduce the latency and improve the performance of your application. They also allow for real-time communication, which is necessary for certain types of applications.
Can I use WebSockets with any server-side language?
Yes, as long as the server-side language supports WebSockets. Node.js, Python, and Ruby are all examples of server-side languages that support WebSockets.
Is it difficult to set up WebSockets in an Angular application?
No, it is relatively easy to set up WebSockets in an Angular application using the WebSocket API. This tutorial provides a step-by-step guide to setting up WebSockets in your Angular 9 application.
