
  Building Real-Time Applications with GraphQL Subscriptions and React
  
    Have you ever wanted to build a web application that can update in real-time, without the user having to refresh the page? With GraphQL subscriptions and React, you can do just that! In this tutorial, we'll show you how to set up GraphQL subscriptions on the server-side and how to use them with the Apollo Client in your React app. By the end of this article, you'll be able to build real-time web applications with ease.
  
  What are GraphQL Subscriptions?
  
    GraphQL is a query language for APIs, and it allows you to build APIs in a way that's flexible and powerful. One of the features that GraphQL provides is subscriptions. Subscriptions are a way to receive real-time updates from an API whenever data changes. With subscriptions, you can build web applications that update in real-time, just like a chat application or a stock ticker.
  
  
    GraphQL subscriptions work by creating a long-lived connection between the client and server. Whenever data changes on the server, it sends a message to all connected clients, and the clients can update their UI accordingly. This is different from a traditional REST API, where the client has to make repeated requests to get the latest data.
  
  
    Now that we have a basic understanding of GraphQL subscriptions, let's dive into building a real-time web application with React and GraphQL subscriptions.
  
  Setting up GraphQL Subscriptions on the Server Side
  
    Before we can use GraphQL subscriptions in our React app, we need to set them up on the server side. In this tutorial, we'll be using Apollo Server and MongoDB.
  
  
    First, let's install the necessary dependencies. Open up your terminal and run the following command:
  
  $ npm install apollo-server graphql mongoose
  
    Next, create a new file called index.js and add the following code:
  
  // index.js
const { ApolloServer, PubSub } = require('apollo-server');
const mongoose = require('mongoose');
const typeDefs = require('./typeDefs');
const resolvers = require('./resolvers');

mongoose.connect('mongodb://localhost:27017/myapp', {
  useNewUrlParser: true,
  useUnifiedTopology: true,
  useFindAndModify: false,
  useCreateIndex: true
}).then(() =&gt; {
  console.log('MongoDB connected');
}).catch((error) =&gt; {
  console.log(error);
});

const pubsub = new PubSub();

const server = new ApolloServer({
  typeDefs,
  resolvers,
  context: ({ req }) =&gt; ({ req, pubsub })
});

server.listen().then(({ url }) =&gt; {
  console.log(`Server listening on ${url}`);
});
  
  
    Let's go through this code step by step. First, we import the necessary dependencies: ApolloServer, PubSub, mongoose, and our own typeDefs and resolvers.
  
  
    Next, we connect to our MongoDB database using mongoose.connect. Make sure to replace myapp with your own database name.
  
  
    We then create a new instance of PubSub, which is used to publish and subscribe to messages.
  
  
    After that, we create a new instance of ApolloServer and pass in our typeDefs, resolvers, and a context object. The context object is where we can pass in any values that we want to make available to our resolvers. In this case, we're passing in req (the current request object) and pubsub (our instance of PubSub).
  
  
    Finally, we start the server and log the URL that it's running on. Our server is now ready to handle GraphQL queries and subscriptions!
  
  Creating the GraphQL Schema
  
    Now that we have our server set up, let's create our GraphQL schema. In this tutorial, we'll be building a simple chat application. We'll have a Message type that represents a message, and a Query, Mutation, and Subscription that allow us to retrieve, create, and subscribe to messages, respectively.
  
  
    Create a new folder called schema, and inside that folder, create a new file called message.js. Add the following code:
  
  // schema/message.js
const { gql } = require('apollo-server');

const typeDefs = gql`
  type Message {
    id: ID!
    text: String!
  }

  type Query {
    messages: [Message]!
  }

  type Mutation {
    addMessage(text: String!): Message!
  }

  type Subscription {
    newMessage: Message!
  }
`;

module.exports = typeDefs;
  
  
    Let's go through this code step by step. First, we import gql from apollo-server.
  
  
    We then define a Message type with two fields: id (an ID) and text (a string).
  
  
    Next, we define a Query type with one field: messages (an array of Message objects).
  
  
    We then define a Mutation type with one field: addMessage (which takes a text argument and returns a Message object).
  
  
    Finally, we define a Subscription type with one field: newMessage (which returns a Message object).
  
  
    We export our schema using module.exports. That's it for our schema!
  
  Creating the Resolvers
  
    Next, let's create our resolvers. Resolvers are functions that handle GraphQL queries, mutations, and subscriptions.
  
  
    Create a new folder called resolvers, and inside that folder, create a new file called message.js. Add the following code:
  
  // resolvers/message.js
const Message = require('../models/Message');
const { PubSub } = require('apollo-server');

const pubsub = new PubSub();

const MESSAGE_ADDED = 'MESSAGE_ADDED';

const resolvers = {
  Query: {
    messages: async () =&gt; {
      const messages = await Message.find().sort({ createdAt: -1 });
      return messages;
    }
  },
  Mutation: {
    addMessage: async (_, { text }) =&gt; {
      const newMessage = new Message({
        text
      });
      const message = await newMessage.save();
      pubsub.publish(MESSAGE_ADDED, { newMessage: message });
      return message;
    }
  },
  Subscription: {
    newMessage: {
      subscribe: () =&gt; pubsub.asyncIterator([MESSAGE_ADDED])
    }
  }
};

module.exports = resolvers;
  
  
    Let's go through this code step by step. First, we import our Message model and PubSub from apollo-server.
  
  
    We then create a new instance of PubSub. This is the same instance that we passed to our Apollo Server earlier.
  
  
    Next, we define a constant called MESSAGE_ADDED that we'll use as the topic for our subscription.
  
  
    We then define our resolvers. First, we have a Query resolver for messages, which returns an array of messages sorted by their createdAt date in descending order.
  
  
    Next, we have a Mutation resolver for addMessage, which takes a text argument and creates a new message in our MongoDB database. We then publish a message to our MESSAGE_ADDED topic using pubsub.publish, and return the newly created message.
  
  
    Finally, we have a Subscription resolver for newMessage, which uses pubsub.asyncIterator to subscribe to our MESSAGE_ADDED topic and return any new messages that are published. This resolver has to return an async iterator, which is what allows it to receive real-time updates.
  
  
    We export our resolvers using module.exports. That's it for our resolvers!
  
  Connecting to the GraphQL API from a React Application
  
    Now that our GraphQL API is set up, let's connect to it from our React application. In this tutorial, we'll be using the Apollo Client to do this.
  
  
    First, let's install the necessary dependencies. Open up your terminal and run the following command:
  
  $ npm install apollo-boost @apollo/react-hooks subscriptions-transport-ws
  
    apollo-boost is a package that provides a pre-configured Apollo Client, @apollo/react-hooks is a package that provides hooks to use with the Apollo Client, and subscriptions-transport-ws is a package that provides WebSocket support for subscriptions.
  
  
    Next, create a new file called index.js in your React app's src folder, and add the following code:
  
  // src/index.js
import React from 'react';
import ReactDOM from 'react-dom';
import { ApolloProvider } from '@apollo/react-hooks';
import { ApolloClient } from 'apollo-client';
import { HttpLink } from 'apollo-link-http';
import { InMemoryCache } from 'apollo-cache-inmemory';
import { WebSocketLink } from 'apollo-link-ws';
import { split } from 'apollo-link';
import { getMainDefinition } from 'apollo-utilities';
import App from './App';

const httpLink = new HttpLink({
  uri: 'http://localhost:4000/graphql'
});

const wsLink = new WebSocketLink({
  uri: 'ws://localhost:4000/graphql',
  options: {
    reconnect: true
  }
});

const link = split(({ query }) =&gt; {
  const definition = getMainDefinition(query);
  return (
    definition.kind === 'OperationDefinition' &amp;&amp;
    definition.operation === 'subscription'
  );
}, wsLink, httpLink);

const client = new ApolloClient({
  link: link,
  cache: new InMemoryCache()
});

ReactDOM.render(
  &lt;ApolloProvider client={client}&gt;
    &lt;App /&gt;
  &lt;/ApolloProvider&gt;,
  document.getElementById('root')
);
  
  
    Let's go through this code step by step. First, we import the necessary dependencies. We're using the WebSocketLink from apollo-link-ws to handle WebSocket subscriptions, and we're using the split function from apollo-link and the getMainDefinition function from apollo-utilities to split our link and send subscriptions over the WebSocketLink and everything else over the HttpLink.
  
  
    Next, we create a new instance of HttpLink with the URL of our GraphQL API.
  
  
    We then create a new instance of WebSocketLink with the WebSocket URL of our GraphQL API, and set the reconnect option to true so that the client automatically reconnects if it loses the WebSocket connection.
  
  
    Next, we create a new link using split that decides whether to use the WebSocketLink or HttpLink based on the type of operation being performed. If it's a subscription, we use the WebSocketLink; if it's anything else, we use the HttpLink.
  
  
    Finally, we create a new instance of ApolloClient with our link and an InMemoryCache, and wrap our App component in an ApolloProvider that passes the client down to all child components.
  
  
    Our React application is now connected to our GraphQL API using the Apollo Client!
  
  Using GraphQL Subscriptions in React
  
    Now that we have our React app connected to our GraphQL API, let's use GraphQL subscriptions to receive real-time updates whenever a new message is added.
  
  
    Create a new file called Chat.js in your React app's src folder, and add the following code:
  
  // src/Chat.js
import React, { useState } from 'react';
import { useSubscription, useMutation } from '@apollo/react-hooks';
import { gql } from 'apollo-boost';

const MESSAGES_QUERY = gql`
  {
    messages {
      id
      text
    }
  }
`;

const MESSAGE_ADDED_SUBSCRIPTION = gql`
  subscription {
    newMessage {
      id
      text
    }
  }
`;

const ADD_MESSAGE_MUTATION = gql`
  mutation AddMessage($text: String!) {
    addMessage(text: $text) {
      id
      text
    }
  }
`;

function Chat() {
  const [text, setText] = useState('');
  const [addMessage] = useMutation(ADD_MESSAGE_MUTATION);

  const sendChatMessage = () =&gt; {
    addMessage({
      variables: {
        text: text
      },
      optimisticResponse: {
        addMessage: {
          __typename: 'Message',
          id: -1,
          text: text
        }
      },
      update: (proxy, { data: { addMessage } }) =&gt; {
        const data = proxy.readQuery({ query: MESSAGES_QUERY });
        data.messages.unshift(addMessage);
        proxy.writeQuery({ query: MESSAGES_QUERY, data });
      }
    });

    setText('');
  };

  const { loading, error, data } = useSubscription(
    MESSAGE_ADDED_SUBSCRIPTION
  );

  if (loading) return &lt;p&gt;Loading...&lt;/p&gt;;
  if (error) return &lt;p&gt;Error: {error.message}&lt;/p&gt;;

  return (
    &lt;div&gt;
      &lt;ul&gt;
        {data.messages.map(message =&gt; (
          &lt;li key={message.id}&gt;{message.text}&lt;/li&gt;
        ))}
      &lt;/ul&gt;
      &lt;div&gt;
        &lt;input type="text" value={text} onChange={e =&gt; setText(e.target.value)} /&gt;
        &lt;button onClick={sendChatMessage}&gt;Send&lt;/button&gt;
      &lt;/div&gt;
    &lt;/div&gt;
  );
}

export default Chat;
  
  
    Let's go through this code step by step. First, we define our MESSAGES_QUERY, which retrieves an array of messages, and our MESSAGE_ADDED_SUBSCRIPTION, which subscribes to new messages.
  
  
    We then define our ADD_MESSAGE_MUTATION, which takes a text argument and creates a new message in our MongoDB database. We're also using optimisticResponse to optimistically update the UI before the server responds, and update to update the cache with the newly created message.
  
  
    We then define our <

<div>
  <h1>Building Real-Time Applications with GraphQL Subscriptions and React</h1>
  <p>
    Have you ever wanted to build a web application that can update in real-time, without the user having to refresh the page? With GraphQL subscriptions and React, you can do just that! In this tutorial, we'll show you how to set up GraphQL subscriptions on the server-side and how to use them with the Apollo Client in your React app. By the end of this article, you'll be able to build real-time web applications with ease.
  </p>
  <h2>What are GraphQL Subscriptions?</h2>
  <p>
    GraphQL is a query language for APIs, and it allows you to build APIs in a way that's flexible and powerful. One of the features that GraphQL provides is subscriptions. Subscriptions are a way to receive real-time updates from an API whenever data changes. With subscriptions, you can build web applications that update in real-time, just like a chat application or a stock ticker.
  </p>
  <p>
    GraphQL subscriptions work by creating a long-lived connection between the client and server. Whenever data changes on the server, it sends a message to all connected clients, and the clients can update their UI accordingly. This is different from a traditional REST API, where the client has to make repeated requests to get the latest data.
  </p>
  <p>
    Now that we have a basic understanding of GraphQL subscriptions, let's dive into building a real-time web application with React and GraphQL subscriptions.
  </p>
  <h2>Setting up GraphQL Subscriptions on the Server Side</h2>
  <p>
    Before we can use GraphQL subscriptions in our React app, we need to set them up on the server side. In this tutorial, we'll be using <a href="https://www.apollographql.com/">Apollo Server</a> and <a href="https://www.mongodb.com/">MongoDB</a>.
  </p>
  <p>
    First, let's install the necessary dependencies. Open up your terminal and run the following command:
  </p>
  <pre><code class="language-bash">$ npm install apollo-server graphql mongoose</code></pre>
  <p>
    Next, create a new file called <code>index.js</code> and add the following code:
  </p>
  <pre><code class="language-javascript">// index.js
const { ApolloServer, PubSub } = require('apollo-server');
const mongoose = require('mongoose');
const typeDefs = require('./typeDefs');
const resolvers = require('./resolvers');

mongoose.connect('mongodb://localhost:27017/myapp', {
  useNewUrlParser: true,
  useUnifiedTopology: true,
  useFindAndModify: false,
  useCreateIndex: true
}).then(() =&gt; {
  console.log('MongoDB connected');
}).catch((error) =&gt; {
  console.log(error);
});

const pubsub = new PubSub();

const server = new ApolloServer({
  typeDefs,
  resolvers,
  context: ({ req }) =&gt; ({ req, pubsub })
});

server.listen().then(({ url }) =&gt; {
  console.log(`Server listening on ${url}`);
});
  </code></pre>
  <p>
    Let's go through this code step by step. First, we import the necessary dependencies: <code>ApolloServer</code>, <code>PubSub</code>, <code>mongoose</code>, and our own <code>typeDefs</code> and <code>resolvers</code>.
  </p>
  <p>
    Next, we connect to our MongoDB database using <code>mongoose.connect</code>. Make sure to replace <code>myapp</code> with your own database name.
  </p>
  <p>
    We then create a new instance of <code>PubSub</code>, which is used to publish and subscribe to messages.
  </p>
  <p>
    After that, we create a new instance of <code>ApolloServer</code> and pass in our <code>typeDefs</code>, <code>resolvers</code>, and a context object. The context object is where we can pass in any values that we want to make available to our resolvers. In this case, we're passing in <code>req</code> (the current request object) and <code>pubsub</code> (our instance of <code>PubSub</code>).
  </p>
  <p>
    Finally, we start the server and log the URL that it's running on. Our server is now ready to handle GraphQL queries and subscriptions!
  </p>
  <h2>Creating the GraphQL Schema</h2>
  <p>
    Now that we have our server set up, let's create our GraphQL schema. In this tutorial, we'll be building a simple chat application. We'll have a <code>Message</code> type that represents a message, and a <code>Query</code>, <code>Mutation</code>, and <code>Subscription</code> that allow us to retrieve, create, and subscribe to messages, respectively.
  </p>
  <p>
    Create a new folder called <code>schema</code>, and inside that folder, create a new file called <code>message.js</code>. Add the following code:
  </p>
  <pre><code class="language-javascript">// schema/message.js
const { gql } = require('apollo-server');

const typeDefs = gql`
  type Message {
    id: ID!
    text: String!
  }

  type Query {
    messages: [Message]!
  }

  type Mutation {
    addMessage(text: String!): Message!
  }

  type Subscription {
    newMessage: Message!
  }
`;

module.exports = typeDefs;
  </code></pre>
  <p>
    Let's go through this code step by step. First, we import <code>gql</code> from <code>apollo-server</code>.
  </p>
  <p>
    We then define a <code>Message</code> type with two fields: <code>id</code> (an ID) and <code>text</code> (a string).
  </p>
  <p>
    Next, we define a <code>Query</code> type with one field: <code>messages</code> (an array of <code>Message</code> objects).
  </p>
  <p>
    We then define a <code>Mutation</code> type with one field: <code>addMessage</code> (which takes a <code>text</code> argument and returns a <code>Message</code> object).
  </p>
  <p>
    Finally, we define a <code>Subscription</code> type with one field: <code>newMessage</code> (which returns a <code>Message</code> object).
  </p>
  <p>
    We export our schema using <code>module.exports</code>. That's it for our schema!
  </p>
  <h2>Creating the Resolvers</h2>
  <p>
    Next, let's create our resolvers. Resolvers are functions that handle GraphQL queries, mutations, and subscriptions.
  </p>
  <p>
    Create a new folder called <code>resolvers</code>, and inside that folder, create a new file called <code>message.js</code>. Add the following code:
  </p>
  <pre><code class="language-javascript">// resolvers/message.js
const Message = require('../models/Message');
const { PubSub } = require('apollo-server');

const pubsub = new PubSub();

const MESSAGE_ADDED = 'MESSAGE_ADDED';

const resolvers = {
  Query: {
    messages: async () =&gt; {
      const messages = await Message.find().sort({ createdAt: -1 });
      return messages;
    }
  },
  Mutation: {
    addMessage: async (_, { text }) =&gt; {
      const newMessage = new Message({
        text
      });
      const message = await newMessage.save();
      pubsub.publish(MESSAGE_ADDED, { newMessage: message });
      return message;
    }
  },
  Subscription: {
    newMessage: {
      subscribe: () =&gt; pubsub.asyncIterator([MESSAGE_ADDED])
    }
  }
};

module.exports = resolvers;
  </code></pre>
  <p>
    Let's go through this code step by step. First, we import our <code>Message</code> model and <code>PubSub</code> from <code>apollo-server</code>.
  </p>
  <p>
    We then create a new instance of <code>PubSub</code>. This is the same instance that we passed to our Apollo Server earlier.
  </p>
  <p>
    Next, we define a constant called <code>MESSAGE_ADDED</code> that we'll use as the topic for our subscription.
  </p>
  <p>
    We then define our resolvers. First, we have a <code>Query</code> resolver for <code>messages</code>, which returns an array of messages sorted by their <code>createdAt</code> date in descending order.
  </p>
  <p>
    Next, we have a <code>Mutation</code> resolver for <code>addMessage</code>, which takes a <code>text</code> argument and creates a new message in our MongoDB database. We then publish a message to our <code>MESSAGE_ADDED</code> topic using <code>pubsub.publish</code>, and return the newly created message.
  </p>
  <p>
    Finally, we have a <code>Subscription</code> resolver for <code>newMessage</code>, which uses <code>pubsub.asyncIterator</code> to subscribe to our <code>MESSAGE_ADDED</code> topic and return any new messages that are published. This resolver has to return an async iterator, which is what allows it to receive real-time updates.
  </p>
  <p>
    We export our resolvers using <code>module.exports</code>. That's it for our resolvers!
  </p>
  <h2>Connecting to the GraphQL API from a React Application</h2>
  <p>
    Now that our GraphQL API is set up, let's connect to it from our React application. In this tutorial, we'll be using the <a href="https://www.apollographql.com/docs/react/">Apollo Client</a> to do this.
  </p>
  <p>
    First, let's install the necessary dependencies. Open up your terminal and run the following command:
  </p>
  <pre><code class="language-bash">$ npm install apollo-boost @apollo/react-hooks subscriptions-transport-ws</code></pre>
  <p>
    <code>apollo-boost</code> is a package that provides a pre-configured Apollo Client, <code>@apollo/react-hooks</code> is a package that provides hooks to use with the Apollo Client, and <code>subscriptions-transport-ws</code> is a package that provides WebSocket support for subscriptions.
  </p>
  <p>
    Next, create a new file called <code>index.js</code> in your React app's <code>src</code> folder, and add the following code:
  </p>
  <pre><code class="language-javascript">// src/index.js
import React from 'react';
import ReactDOM from 'react-dom';
import { ApolloProvider } from '@apollo/react-hooks';
import { ApolloClient } from 'apollo-client';
import { HttpLink } from 'apollo-link-http';
import { InMemoryCache } from 'apollo-cache-inmemory';
import { WebSocketLink } from 'apollo-link-ws';
import { split } from 'apollo-link';
import { getMainDefinition } from 'apollo-utilities';
import App from './App';

const httpLink = new HttpLink({
  uri: 'http://localhost:4000/graphql'
});

const wsLink = new WebSocketLink({
  uri: 'ws://localhost:4000/graphql',
  options: {
    reconnect: true
  }
});

const link = split(({ query }) =&gt; {
  const definition = getMainDefinition(query);
  return (
    definition.kind === 'OperationDefinition' &amp;&amp;
    definition.operation === 'subscription'
  );
}, wsLink, httpLink);

const client = new ApolloClient({
  link: link,
  cache: new InMemoryCache()
});

ReactDOM.render(
  &lt;ApolloProvider client={client}&gt;
    &lt;App /&gt;
  &lt;/ApolloProvider&gt;,
  document.getElementById('root')
);
  </code></pre>
  <p>
    Let's go through this code step by step. First, we import the necessary dependencies. We're using the WebSocketLink from <code>apollo-link-ws</code> to handle WebSocket subscriptions, and we're using the split function from <code>apollo-link</code> and the getMainDefinition function from <code>apollo-utilities</code> to split our link and send subscriptions over the WebSocketLink and everything else over the HttpLink.
  </p>
  <p>
    Next, we create a new instance of <code>HttpLink</code> with the URL of our GraphQL API.
  </p>
  <p>
    We then create a new instance of <code>WebSocketLink</code> with the WebSocket URL of our GraphQL API, and set the <code>reconnect</code> option to true so that the client automatically reconnects if it loses the WebSocket connection.
  </p>
  <p>
    Next, we create a new link using <code>split</code> that decides whether to use the WebSocketLink or HttpLink based on the type of operation being performed. If it's a subscription, we use the WebSocketLink; if it's anything else, we use the HttpLink.
  </p>
  <p>
    Finally, we create a new instance of <code>ApolloClient</code> with our link and an <code>InMemoryCache</code>, and wrap our <code>App</code> component in an <code>ApolloProvider</code> that passes the client down to all child components.
  </p>
  <p>
    Our React application is now connected to our GraphQL API using the Apollo Client!
  </p>
  <h2>Using GraphQL Subscriptions in React</h2>
  <p>
    Now that we have our React app connected to our GraphQL API, let's use GraphQL subscriptions to receive real-time updates whenever a new message is added.
  </p>
  <p>
    Create a new file called <code>Chat.js</code> in your React app's <code>src</code> folder, and add the following code:
  </p>
  <pre><code class="language-javascript">// src/Chat.js
import React, { useState } from 'react';
import { useSubscription, useMutation } from '@apollo/react-hooks';
import { gql } from 'apollo-boost';

const MESSAGES_QUERY = gql`
  {
    messages {
      id
      text
    }
  }
`;

const MESSAGE_ADDED_SUBSCRIPTION = gql`
  subscription {
    newMessage {
      id
      text
    }
  }
`;

const ADD_MESSAGE_MUTATION = gql`
  mutation AddMessage($text: String!) {
    addMessage(text: $text) {
      id
      text
    }
  }
`;

function Chat() {
  const [text, setText] = useState('');
  const [addMessage] = useMutation(ADD_MESSAGE_MUTATION);

  const sendChatMessage = () =&gt; {
    addMessage({
      variables: {
        text: text
      },
      optimisticResponse: {
        addMessage: {
          __typename: 'Message',
          id: -1,
          text: text
        }
      },
      update: (proxy, { data: { addMessage } }) =&gt; {
        const data = proxy.readQuery({ query: MESSAGES_QUERY });
        data.messages.unshift(addMessage);
        proxy.writeQuery({ query: MESSAGES_QUERY, data });
      }
    });

    setText('');
  };

  const { loading, error, data } = useSubscription(
    MESSAGE_ADDED_SUBSCRIPTION
  );

  if (loading) return &lt;p&gt;Loading...&lt;/p&gt;;
  if (error) return &lt;p&gt;Error: {error.message}&lt;/p&gt;;

  return (
    &lt;div&gt;
      &lt;ul&gt;
        {data.messages.map(message =&gt; (
          &lt;li key={message.id}&gt;{message.text}&lt;/li&gt;
        ))}
      &lt;/ul&gt;
      &lt;div&gt;
        &lt;input type="text" value={text} onChange={e =&gt; setText(e.target.value)} /&gt;
        &lt;button onClick={sendChatMessage}&gt;Send&lt;/button&gt;
      &lt;/div&gt;
    &lt;/div&gt;
  );
}

export default Chat;
  </code></pre>
  <p>
    Let's go through this code step by step. First, we define our <code>MESSAGES_QUERY</code>, which retrieves an array of messages, and our <code>MESSAGE_ADDED_SUBSCRIPTION</code>, which subscribes to new messages.
  </p>
  <p>
    We then define our <code>ADD_MESSAGE_MUTATION</code>, which takes a <code>text</code> argument and creates a new message in our MongoDB database. We're also using <code>optimisticResponse</code> to optimistically update the UI before the server responds, and <code>update</code> to update the cache with the newly created message.
  </p>
  <p>
    We then define our <

Learn how to create real-time web applications using GraphQL subscriptions in combination with React for a seamless user experience. Explore how to set up GraphQL subscriptions on the server-side and how to use them with the Apollo Client in your React app.

Building Real-Time Applications with GraphQL Subscriptions and React


  Effortless Cloud Deployment: Automating Fullstack Apps with GitHub Actions and Vercel
  Web development can be a tedious and time-consuming process, especially when it comes to deploying your application to the cloud. However, there is an easier way to deploy your fullstack web applications to the cloud, by automating the process using GitHub Actions and Vercel. By following this step-by-step tutorial, you can learn how to automate your fullstack web app from start to finish, making deployment quicker, simpler, and more efficient than ever before.
  What is GitHub Actions?
  GitHub Actions is a tool developed by GitHub, which allows developers to automate workflows, from build and testing to deployment and beyond. By defining workflows in a YAML file, you can run custom scripts and connect with other tools to achieve a variety of automation tasks, reducing the potential for human error and making the development process more uniform and consistent. The powerful automation capabilities of GitHub Actions can be used in a variety of ways, including building and testing your applications, deploying your applications, and automating repetitive tasks like code formatting and linting.
  What is Vercel?
  Vercel is a cloud platform that provides a serverless environment for building, running, and deploying your web applications. With Vercel, you can achieve fast and reliable deployment, automatic scaling, and effortless integration with tools like GitHub, GitLab, and Bitbucket. Vercel supports a variety of frameworks for frontend and backend development, including Next.js, React, Vue, and Node.js, making it an ideal solution for fullstack web development. Additionally, Vercel provides an intuitive and user-friendly interface for managing your web applications, including deployment previews, custom domains, and HTTPS encryption.
  Building a Fullstack Web Application
  Before we can deploy our fullstack web application with GitHub Actions and Vercel, we first need to build our application. In this example, we will be building a simple fullstack web application, consisting of a frontend built with React and a backend built with Node.js and Express. To get started, create a new directory for your project, and initialize it as a new git repository:
  
    mkdir my-project
    cd my-project
    git init
  
  Next, create a client directory for your frontend code, and a server directory for your backend code:
  
    mkdir client
    mkdir server
  
  Inside your client directory, initialize your React project using create-react-app:
  
    cd client
    npx create-react-app .
  
  Inside your server directory, initialize your Node.js project using npm:
  
    cd ../server
    npm init -y
  
  Next, install the necessary dependencies for your backend code:
  
    npm install express cors
  
  Create a new file index.js inside your server directory, and add the following code:
  
    
  const express = require('express');
  const cors = require('cors');

  const app = express();

  app.use(cors())
  app.use(express.json());

  app.get('/api/hello', (req, res) => {
    res.send({ message: 'Hello from the server!' });
  });

  const port = process.env.PORT || 5000;
  app.listen(port, () => {
    console.log(`Server running on port ${port}`);
  });
    
  
  This code sets up a simple Express server, which listens on port 5000 and responds to a GET request on the URL /api/hello, returning a simple message.
  Finally, create a new file Dockerfile inside your server directory, and add the following code:
  
    
  FROM node:14

  WORKDIR /usr/src/app

  COPY package*.json ./

  RUN npm install

  COPY . .

  EXPOSE 5000

  CMD [ "npm", "start" ]
    
  
  This code sets up a Docker container for your Node.js application, based on the official Node.js Docker image, and sets the working directory to /usr/src/app. Next, it copies over your package.json and package-lock.json files, and runs npm install to install your project dependencies. Finally, it copies over the rest of your application code, exposes port 5000, and sets the command to run npm start.
  At this point, your fullstack web application is complete, and can be tested locally by starting both the React development server and the Express server:
  
    cd ../client
    npm start
    cd ../server
    npm start
  
  This will start your frontend at localhost:3000 and your backend at localhost:5000.
  Deploying with GitHub Actions and Vercel
  Now that we have our fullstack web application, it's time to deploy it to the cloud using GitHub Actions and Vercel. First, let's create a new GitHub repository for our code, and push our code to that repository:
  
    git remote add origin git@github.com:YOUR_USERNAME/YOUR_REPOSITORY.git
    git add .
    git commit -m "Initial commit"
    git push -u origin master
  
  Next, create a new file .github/workflows/build-deploy.yml, and add the following code:
  
    
  name: Build and Deploy

  on:
    push:
      branches:
        - master

  jobs:
    build:
      runs-on: ubuntu-latest

      steps:
        - uses: actions/checkout@v2
        - name: Set up Node.js
          uses: actions/setup-node@v1
          with:
            node-version: '14.x'
        - name: Build and Test
          run: |
            cd client
            npm install
            npm run build
            cd ../server
            npm install
            npm test
        - name: Deploy to Vercel
          uses: amondnet/vercel-action@v1
          with:
            vercel-token: ${{ secrets.VERCEL_TOKEN }}
          env:
            GITHUB_SHA: ${{ github.sha }}
            VERCEL_ENV: production
    
  
  This code defines a GitHub Actions workflow that runs every time code is pushed to the master branch. The workflow has three steps: checking out the code using the actions/checkout action, preparing the environment using the actions/setup-node action, and running the build and test scripts for our application using npm. If the build and test steps succeed, the workflow deploys the application to Vercel using the amondnet/vercel-action action.
  To use the amondnet/vercel-action action, we first need to generate a Vercel token, which we can do by following these steps:
  
    Log in to the Vercel dashboard and navigate to the settings page for your account. 
    Under "Tokens", click "Create Token". 
    Enter a name for your token, and select the "Production, Preview, and Development" scopes.
    Click "Create Token" to generate your token.
  
  Once you have generated your token, navigate to the settings page for your GitHub repository, and navigate to the "Secrets" tab. Click "New Secret", and enter "VERCEL_TOKEN" as the name, and paste in your token value as the value.
  Now, every time you push code to the master branch of your GitHub repository, the application will be built, tested, and deployed to the cloud using Vercel. You can view your deployed application by navigating to your Vercel dashboard, where you should see a new deployment for your application. Clicking on the deployment will reveal a unique URL where you can access your application online.
  Conclusion
  Automating the deployment process for your fullstack web applications can save you time and effort by reducing the potential for human error and making the process more consistent and efficient. By using GitHub Actions and Vercel, you can build, test, and deploy your fullstack web applications with ease, leaving you with more time to focus on developing your application and delivering great user experiences. Try it out for yourself, and see how effortless fullstack web development can be!


<div>
  <h1>Effortless Cloud Deployment: Automating Fullstack Apps with GitHub Actions and Vercel</h1>
  <p>Web development can be a tedious and time-consuming process, especially when it comes to deploying your application to the cloud. However, there is an easier way to deploy your fullstack web applications to the cloud, by automating the process using GitHub Actions and Vercel. By following this step-by-step tutorial, you can learn how to automate your fullstack web app from start to finish, making deployment quicker, simpler, and more efficient than ever before.</p>
  <h2>What is GitHub Actions?</h2>
  <p>GitHub Actions is a tool developed by GitHub, which allows developers to automate workflows, from build and testing to deployment and beyond. By defining workflows in a YAML file, you can run custom scripts and connect with other tools to achieve a variety of automation tasks, reducing the potential for human error and making the development process more uniform and consistent. The powerful automation capabilities of GitHub Actions can be used in a variety of ways, including building and testing your applications, deploying your applications, and automating repetitive tasks like code formatting and linting.</p>
  <h2>What is Vercel?</h2>
  <p>Vercel is a cloud platform that provides a serverless environment for building, running, and deploying your web applications. With Vercel, you can achieve fast and reliable deployment, automatic scaling, and effortless integration with tools like GitHub, GitLab, and Bitbucket. Vercel supports a variety of frameworks for frontend and backend development, including Next.js, React, Vue, and Node.js, making it an ideal solution for fullstack web development. Additionally, Vercel provides an intuitive and user-friendly interface for managing your web applications, including deployment previews, custom domains, and HTTPS encryption.</p>
  <h2>Building a Fullstack Web Application</h2>
  <p>Before we can deploy our fullstack web application with GitHub Actions and Vercel, we first need to build our application. In this example, we will be building a simple fullstack web application, consisting of a frontend built with React and a backend built with Node.js and Express. To get started, create a new directory for your project, and initialize it as a new git repository:</p>
  <code>
    mkdir my-project<br>
    cd my-project<br>
    git init
  </code>
  <p>Next, create a <code>client</code> directory for your frontend code, and a <code>server</code> directory for your backend code:</p>
  <code>
    mkdir client<br>
    mkdir server
  </code>
  <p>Inside your <code>client</code> directory, initialize your React project using <code>create-react-app</code>:</p>
  <code>
    cd client<br>
    npx create-react-app .
  </code>
  <p>Inside your <code>server</code> directory, initialize your Node.js project using <code>npm</code>:</p>
  <code>
    cd ../server<br>
    npm init -y
  </code>
  <p>Next, install the necessary dependencies for your backend code:</p>
  <code>
    npm install express cors
  </code>
  <p>Create a new file <code>index.js</code> inside your <code>server</code> directory, and add the following code:</p>
  <pre>
    <code>
  const express = require('express');
  const cors = require('cors');

  const app = express();

  app.use(cors())
  app.use(express.json());

  app.get('/api/hello', (req, res) => {
    res.send({ message: 'Hello from the server!' });
  });

  const port = process.env.PORT || 5000;
  app.listen(port, () => {
    console.log(`Server running on port ${port}`);
  });
    </code>
  </pre>
  <p>This code sets up a simple Express server, which listens on port 5000 and responds to a GET request on the URL <code>/api/hello</code>, returning a simple message.</p>
  <p>Finally, create a new file <code>Dockerfile</code> inside your <code>server</code> directory, and add the following code:</p>
  <pre>
    <code>
  FROM node:14

  WORKDIR /usr/src/app

  COPY package*.json ./

  RUN npm install

  COPY . .

  EXPOSE 5000

  CMD [ "npm", "start" ]
    </code>
  </pre>
  <p>This code sets up a Docker container for your Node.js application, based on the official Node.js Docker image, and sets the working directory to <code>/usr/src/app</code>. Next, it copies over your package.json and package-lock.json files, and runs <code>npm install</code> to install your project dependencies. Finally, it copies over the rest of your application code, exposes port 5000, and sets the command to run <code>npm start</code>.</p>
  <p>At this point, your fullstack web application is complete, and can be tested locally by starting both the React development server and the Express server:</p>
  <code>
    cd ../client<br>
    npm start</br>
    cd ../server</br>
    npm start
  </code>
  <p>This will start your frontend at <code>localhost:3000</code> and your backend at <code>localhost:5000</code>.</p>
  <h2>Deploying with GitHub Actions and Vercel</h2>
  <p>Now that we have our fullstack web application, it's time to deploy it to the cloud using GitHub Actions and Vercel. First, let's create a new GitHub repository for our code, and push our code to that repository:</p>
  <code>
    git remote add origin git@github.com:YOUR_USERNAME/YOUR_REPOSITORY.git<br>
    git add .<br>
    git commit -m "Initial commit"<br>
    git push -u origin master
  </code>
  <p>Next, create a new file <code>.github/workflows/build-deploy.yml</code>, and add the following code:</p>
  <pre>
    <code>
  name: Build and Deploy

  on:
    push:
      branches:
        - master

  jobs:
    build:
      runs-on: ubuntu-latest

      steps:
        - uses: actions/checkout@v2
        - name: Set up Node.js
          uses: actions/setup-node@v1
          with:
            node-version: '14.x'
        - name: Build and Test
          run: |
            cd client
            npm install
            npm run build
            cd ../server
            npm install
            npm test
        - name: Deploy to Vercel
          uses: amondnet/vercel-action@v1
          with:
            vercel-token: ${{ secrets.VERCEL_TOKEN }}
          env:
            GITHUB_SHA: ${{ github.sha }}
            VERCEL_ENV: production
    </code>
  </pre>
  <p>This code defines a GitHub Actions workflow that runs every time code is pushed to the master branch. The workflow has three steps: checking out the code using the <code>actions/checkout</code> action, preparing the environment using the <code>actions/setup-node</code> action, and running the build and test scripts for our application using npm. If the build and test steps succeed, the workflow deploys the application to Vercel using the <code>amondnet/vercel-action</code> action.</p>
  <p>To use the <code>amondnet/vercel-action</code> action, we first need to generate a Vercel token, which we can do by following these steps:</p>
  <ol>
    <li>Log in to the Vercel dashboard and navigate to the settings page for your account. </li>
    <li>Under "Tokens", click "Create Token". </li>
    <li>Enter a name for your token, and select the "Production, Preview, and Development" scopes.</li>
    <li>Click "Create Token" to generate your token.</li>
  </ol>
  <p>Once you have generated your token, navigate to the settings page for your GitHub repository, and navigate to the "Secrets" tab. Click "New Secret", and enter "VERCEL_TOKEN" as the name, and paste in your token value as the value.</p>
  <p>Now, every time you push code to the master branch of your GitHub repository, the application will be built, tested, and deployed to the cloud using Vercel. You can view your deployed application by navigating to your Vercel dashboard, where you should see a new deployment for your application. Clicking on the deployment will reveal a unique URL where you can access your application online.</p>
  <h2>Conclusion</h2>
  <p>Automating the deployment process for your fullstack web applications can save you time and effort by reducing the potential for human error and making the process more consistent and efficient. By using GitHub Actions and Vercel, you can build, test, and deploy your fullstack web applications with ease, leaving you with more time to focus on developing your application and delivering great user experiences. Try it out for yourself, and see how effortless fullstack web development can be!</p>
</div>

Discover the power of automation in fullstack web development by learning to build, test, and deploy responsive web applications using GitHub Actions and Vercel. This step-by-step tutorial will guide you through the process of automating your web app from start to finish.

Effortless Cloud Deployment: Automating Fullstack Apps with GitHub Actions and Vercel


  Simplifying Authentication: A Comprehensive Guide to Implementing Auth0 with React and Next.js
  As web applications become more complex, user authentication and access control become critical components. However, building a scalable, secure, and easy-to-use authentication system can be a daunting task. Fortunately, Auth0 provides a powerful and flexible identity management platform that makes implementing authentication solutions a breeze. In this tutorial, we will explore how to integrate Auth0 with React and Next.js to simplify and streamline your application's authentication process.

  What is Auth0?
  Auth0 is a cloud-based identity management platform that provides authentication and authorization solutions for web, mobile, and legacy applications. With Auth0, you can easily add social and enterprise identity providers, such as Google, Facebook, and Microsoft, to your application without having to deal with the complexities of each individual integration.

  Getting Started with Auth0
  Before we dive into integrating Auth0 with our React and Next.js application, we need to set up an Auth0 account and create a new application.

  
    Navigate to the Auth0 website and create an account if you don't already have one.
    Create a new application by clicking on the "Applications" tab in the dashboard and selecting "Create Application".
    Choose "Single Page Web Applications" as the application type.
    Provide a name for your application, and make sure the "Development" environment is selected.
    Under the "Settings" tab, configure the following fields:
    
      Allowed Callback URLs: set this to "http://localhost:3000/callback" (assuming you are running your application locally on port 3000). This URL will be used by Auth0 to redirect the user after authentication.
      Allowed Logout URLs: set this to "http://localhost:3000" (assuming you are running your application locally on port 3000). This URL will be used by Auth0 to redirect the user after logging out.
    
    Save your changes to the application settings.
  

  Integrating Auth0 with React and Next.js
  Now that we have our Auth0 account and application set up, let's integrate it with our React and Next.js application.

  First, we need to install the necessary Auth0 packages:

  
    npm install --save auth0-js react-auth0-wrapper
  

  Next, we need to create a configuration file for our Auth0 setup. Create a new file called `auth0.js` in your project's root directory and add the following code:

  
    import auth0 from 'auth0-js';

    class Auth0 {
      constructor() {
        this.auth0 = new auth0.WebAuth({
          domain: '',
          clientID: '',
          redirectUri: 'http://localhost:3000/callback',
          responseType: 'token id_token',
          scope: 'openid profile email'
        });
      }

      login = () => {
        this.auth0.authorize();
      }

      handleAuthentication = () => {
        return new Promise((resolve, reject) => {
          this.auth0.parseHash((err, authResult) => {
            if (authResult && authResult.accessToken && authResult.idToken) {
              this.setSession(authResult);
              resolve();
            } else if (err) {
              reject(err);
            }
          });
        });
      }

      setSession = (authResult) => {
        // Set the time that the access token will expire at
        let expiresAt = JSON.stringify(
          authResult.expiresIn * 1000 + new Date().getTime()
        );

        localStorage.setItem('access_token', authResult.accessToken);
        localStorage.setItem('id_token', authResult.idToken);
        localStorage.setItem('expires_at', expiresAt);
      }

      isAuthenticated = () => {
        let expiresAt = JSON.parse(localStorage.getItem('expires_at'));
        return new Date().getTime()  {
        localStorage.removeItem('access_token');
        localStorage.removeItem('id_token');
        localStorage.removeItem('expires_at');
        this.auth0.logout({
          returnTo: window.location.origin
        });
      }
    }

    const auth0Client = new Auth0();

    export default auth0Client;
  

  Make sure to replace `` and `` with the corresponding values from your Auth0 application settings.

  This code sets up an `Auth0` class with methods for logging in, handling authentication, checking authentication status, and logging out. It also uses `localStorage` to store the user's access and ID tokens.

  Next, we need to create a higher-order component (HOC) that will wrap our application and provide access to the `Auth0` methods. Create a new file called `withAuth.js` in your project's root directory and add the following code:

  
    import React, { useState, useEffect, useContext } from 'react';
    import auth0Client from './auth0';

    const AuthContext = React.createContext(null);

    export const useAuth = () => useContext(AuthContext);

    function AuthProvider({ children }) {
      const [isAuthenticated, setIsAuthenticated] = useState(false);
      const [user, setUser] = useState(null);
      const [authLoading, setAuthLoading] = useState(true);

      useEffect(() => {
        const initializeAuth = async () => {
          try {
            if (window.location.search.includes('code=')) {
              await auth0Client.handleAuthentication();
            }

            setIsAuthenticated(auth0Client.isAuthenticated());

            if (isAuthenticated) {
              setUser(auth0Client.getUser());
            }
          } catch (error) {
            console.error(error);
          } finally {
            setAuthLoading(false);
          }
        };

        initializeAuth();
      }, [isAuthenticated]);

      const login = () => auth0Client.login();
      const logout = () => auth0Client.logout();

      const contextValue = {
        isAuthenticated,
        user,
        login,
        logout,
        authLoading
      };

      if (authLoading) {
        return Loading authentication...;
      }

      return (
        
          {children}
        
      );
    }

    export default AuthProvider;
  

  The `AuthProvider` component uses React's `useEffect` hook to initialize the authentication state. It also provides a `useAuth` hook for accessing the authentication methods and state from within child components. The `authLoading` state is used to display a loading message while the authentication state is being initialized.

  Now that we have our Auth0 setup and authentication provider in place, we can start using it in our application. In your `pages/_app.js` file, wrap your application with the `AuthProvider` component:

  
    import AuthProvider from '../components/AuthProvider';

    function MyApp({ Component, pageProps }) {
      return (
        &lt;AuthProvider>
          &lt;Component {...pageProps} />
        &lt;/AuthProvider>
      );
    }

    export default MyApp;
  

  Now, any component in your application can access the authentication state and methods using the `useAuth` hook:

  
    import { useAuth } from '../components/AuthProvider';

    function Profile() {  
      const { isAuthenticated, user, login, logout } = useAuth();

      if (!isAuthenticated) {
        return Please login to view your profile.;
      }

      return (
        &lt;div>
          &lt;h1>Welcome, {user.nickname}!
          &lt;button onClick={() => logout()}>Logout
        &lt;/div>
      );
    }
  

  Security Best Practices
  When implementing user authentication, it is essential to follow security best practices to protect your application and user data. Here are some tips to keep in mind:

  
    Use HTTPS: All traffic between your application and the Auth0 servers should be encrypted using HTTPS. Make sure to use SSL certificates issued by trusted certificate authorities.
    Validate input: Always validate user input to prevent attacks such as SQL injection and cross-site scripting (XSS).
    Encode output: Encode any data sent to the user to prevent XSS attacks.
    Limit access privileges: Limit user access to only the necessary parts of your application. Use roles and permissions to control access to resources and actions.
    Use two-factor authentication: Enable two-factor authentication (2FA) to add an extra layer of security to your application.
    Store user data securely: Passwords should be hashed and salted before storing them in your database.
  

  Conclusion
  Auth0 provides an easy and secure way to implement user authentication in your React and Next.js applications. By following the steps outlined in this tutorial, you can quickly set up an Auth0 account and integrate it with your application. Remember to follow security best practices when implementing authentication and access control, and always keep user data safe.


<div>
  <h1>Simplifying Authentication: A Comprehensive Guide to Implementing Auth0 with React and Next.js</h1>
  <p>As web applications become more complex, user authentication and access control become critical components. However, building a scalable, secure, and easy-to-use authentication system can be a daunting task. Fortunately, Auth0 provides a powerful and flexible identity management platform that makes implementing authentication solutions a breeze. In this tutorial, we will explore how to integrate Auth0 with React and Next.js to simplify and streamline your application's authentication process.</p>

  <h2>What is Auth0?</h2>
  <p>Auth0 is a cloud-based identity management platform that provides authentication and authorization solutions for web, mobile, and legacy applications. With Auth0, you can easily add social and enterprise identity providers, such as Google, Facebook, and Microsoft, to your application without having to deal with the complexities of each individual integration.</p>

  <h2>Getting Started with Auth0</h2>
  <p>Before we dive into integrating Auth0 with our React and Next.js application, we need to set up an Auth0 account and create a new application.</p>

  <ol>
    <li>Navigate to the Auth0 website and create an account if you don't already have one.</li>
    <li>Create a new application by clicking on the "Applications" tab in the dashboard and selecting "Create Application".</li>
    <li>Choose "Single Page Web Applications" as the application type.</li>
    <li>Provide a name for your application, and make sure the "Development" environment is selected.</li>
    <li>Under the "Settings" tab, configure the following fields:</li>
    <ul>
      <li><strong>Allowed Callback URLs</strong>: set this to "http://localhost:3000/callback" (assuming you are running your application locally on port 3000). This URL will be used by Auth0 to redirect the user after authentication.</li>
      <li><strong>Allowed Logout URLs</strong>: set this to "http://localhost:3000" (assuming you are running your application locally on port 3000). This URL will be used by Auth0 to redirect the user after logging out.</li>
    </ul>
    <li>Save your changes to the application settings.</li>
  </ol>

  <h2>Integrating Auth0 with React and Next.js</h2>
  <p>Now that we have our Auth0 account and application set up, let's integrate it with our React and Next.js application.</p>

  <p>First, we need to install the necessary Auth0 packages:</p>

  <pre><code class="language-bash">
    npm install --save auth0-js react-auth0-wrapper
  </code></pre>

  <p>Next, we need to create a configuration file for our Auth0 setup. Create a new file called `auth0.js` in your project's root directory and add the following code:</p>

  <pre><code class="language-javascript">
    import auth0 from 'auth0-js';

    class Auth0 {
      constructor() {
        this.auth0 = new auth0.WebAuth({
          domain: '<YOUR_AUTH0_DOMAIN>',
          clientID: '<YOUR_AUTH0_CLIENT_ID>',
          redirectUri: 'http://localhost:3000/callback',
          responseType: 'token id_token',
          scope: 'openid profile email'
        });
      }

      login = () => {
        this.auth0.authorize();
      }

      handleAuthentication = () => {
        return new Promise((resolve, reject) => {
          this.auth0.parseHash((err, authResult) => {
            if (authResult && authResult.accessToken && authResult.idToken) {
              this.setSession(authResult);
              resolve();
            } else if (err) {
              reject(err);
            }
          });
        });
      }

      setSession = (authResult) => {
        // Set the time that the access token will expire at
        let expiresAt = JSON.stringify(
          authResult.expiresIn * 1000 + new Date().getTime()
        );

        localStorage.setItem('access_token', authResult.accessToken);
        localStorage.setItem('id_token', authResult.idToken);
        localStorage.setItem('expires_at', expiresAt);
      }

      isAuthenticated = () => {
        let expiresAt = JSON.parse(localStorage.getItem('expires_at'));
        return new Date().getTime() < expiresAt;
      }

      logout = () => {
        localStorage.removeItem('access_token');
        localStorage.removeItem('id_token');
        localStorage.removeItem('expires_at');
        this.auth0.logout({
          returnTo: window.location.origin
        });
      }
    }

    const auth0Client = new Auth0();

    export default auth0Client;
  </code></pre>

  <p>Make sure to replace `<YOUR_AUTH0_DOMAIN>` and `<YOUR_AUTH0_CLIENT_ID>` with the corresponding values from your Auth0 application settings.</p>

  <p>This code sets up an `Auth0` class with methods for logging in, handling authentication, checking authentication status, and logging out. It also uses `localStorage` to store the user's access and ID tokens.</p>

  <p>Next, we need to create a higher-order component (HOC) that will wrap our application and provide access to the `Auth0` methods. Create a new file called `withAuth.js` in your project's root directory and add the following code:</p>

  <pre><code class="language-javascript">
    import React, { useState, useEffect, useContext } from 'react';
    import auth0Client from './auth0';

    const AuthContext = React.createContext(null);

    export const useAuth = () => useContext(AuthContext);

    function AuthProvider({ children }) {
      const [isAuthenticated, setIsAuthenticated] = useState(false);
      const [user, setUser] = useState(null);
      const [authLoading, setAuthLoading] = useState(true);

      useEffect(() => {
        const initializeAuth = async () => {
          try {
            if (window.location.search.includes('code=')) {
              await auth0Client.handleAuthentication();
            }

            setIsAuthenticated(auth0Client.isAuthenticated());

            if (isAuthenticated) {
              setUser(auth0Client.getUser());
            }
          } catch (error) {
            console.error(error);
          } finally {
            setAuthLoading(false);
          }
        };

        initializeAuth();
      }, [isAuthenticated]);

      const login = () => auth0Client.login();
      const logout = () => auth0Client.logout();

      const contextValue = {
        isAuthenticated,
        user,
        login,
        logout,
        authLoading
      };

      if (authLoading) {
        return <p>Loading authentication...</p>;
      }

      return (
        <AuthContext.Provider value={contextValue}>
          {children}
        </AuthContext.Provider>
      );
    }

    export default AuthProvider;
  </code></pre>

  <p>The `AuthProvider` component uses React's `useEffect` hook to initialize the authentication state. It also provides a `useAuth` hook for accessing the authentication methods and state from within child components. The `authLoading` state is used to display a loading message while the authentication state is being initialized.</p>

  <p>Now that we have our Auth0 setup and authentication provider in place, we can start using it in our application. In your `pages/_app.js` file, wrap your application with the `AuthProvider` component:</p>

  <pre><code class="language-javascript">
    import AuthProvider from '../components/AuthProvider';

    function MyApp({ Component, pageProps }) {
      return (
        &lt;AuthProvider>
          &lt;Component {...pageProps} />
        &lt;/AuthProvider>
      );
    }

    export default MyApp;
  </code></pre>

  <p>Now, any component in your application can access the authentication state and methods using the `useAuth` hook:</p>

  <pre><code class="language-javascript">
    import { useAuth } from '../components/AuthProvider';

    function Profile() {  
      const { isAuthenticated, user, login, logout } = useAuth();

      if (!isAuthenticated) {
        return <p>Please login to view your profile.</p>;
      }

      return (
        &lt;div>
          &lt;h1>Welcome, {user.nickname}!</h1>
          &lt;button onClick={() => logout()}>Logout</button>
        &lt;/div>
      );
    }
  </code></pre>

  <h2>Security Best Practices</h2>
  <p>When implementing user authentication, it is essential to follow security best practices to protect your application and user data. Here are some tips to keep in mind:</p>

  <ol>
    <li><strong>Use HTTPS</strong>: All traffic between your application and the Auth0 servers should be encrypted using HTTPS. Make sure to use SSL certificates issued by trusted certificate authorities.</li>
    <li><strong>Validate input</strong>: Always validate user input to prevent attacks such as SQL injection and cross-site scripting (XSS).</li>
    <li><strong>Encode output</strong>: Encode any data sent to the user to prevent XSS attacks.</li>
    <li><strong>Limit access privileges</strong>: Limit user access to only the necessary parts of your application. Use roles and permissions to control access to resources and actions.</li>
    <li><strong>Use two-factor authentication</strong>: Enable two-factor authentication (2FA) to add an extra layer of security to your application.</li>
    <li><strong>Store user data securely</strong>: Passwords should be hashed and salted before storing them in your database.</li>
  </ol>

  <h2>Conclusion</h2>
  <p>Auth0 provides an easy and secure way to implement user authentication in your React and Next.js applications. By following the steps outlined in this tutorial, you can quickly set up an Auth0 account and integrate it with your application. Remember to follow security best practices when implementing authentication and access control, and always keep user data safe.</p>
</div>

Learn how to easily implement user authentication in your React and Next.js applications using Auth0, a powerful and flexible identity management platform. Explore best practices for securing your app, handling user sessions, and managing roles and permissions.

Simplifying Authentication: A Comprehensive Guide to Implementing Auth0 with React and Next.js



Powerful Real-time Features with Socket.IO: Introductory Tutorial for Fullstack Developers

In modern web development, real-time features are becoming increasingly popular. Whether it is for chat applications, notifications, or live updates, the ability to update your website or application in real-time has become a necessity. Socket.IO is one of the most popular libraries for real-time web applications, offering a simple, yet powerful solution for full-stack development. In this tutorial, we will guide you through creating a basic chat application using Socket.IO for real-time communication. 

What is Socket.IO?

Socket.IO is a JavaScript library that enables real-time, bi-directional communication between the web clients and the server. It provides developers with a simple and powerful API that abstracts away the complexity of WebSocket and TCP protocols. The beauty of Socket.IO is its ability to work across different platforms, providing low-latency communication that's essential for real-time applications. 

Getting Started with Socket.IO

The first step in using Socket.IO is to install the library. It's important to note that Socket.IO consists of two parts, one for the server and one for the client. In this tutorial, we will be using Node.js as our server, and the Socket.IO client will be included as a script in our HTML page.

npm install socket.io

Once installed, we can then create a basic Node.js server that will listen on a specific port and serve a basic HTML page:

//Importing the required modules
const http = require('http');
const fs = require('fs');
const path = require('path');

//Creating the HTTP server
const server = http.createServer((req, res) =&gt; {
  //Serving the basic HTML page
  if (req.url === '/') {
    fs.readFile(path.join(__dirname, 'index.html'), (err, data) =&gt; {
      if (err) {
        res.writeHead(500, { 'Content-Type': 'text/plain' });
        res.end('Internal Server Error');
      } else {
        res.writeHead(200, { 'Content-Type': 'text/html' });
        res.end(data);
      }
    });
  } else {
    res.writeHead(404, { 'Content-Type': 'text/plain' });
    res.end('Page Not Found');
  }
});

//Listening on port 3000
server.listen(3000, () =&gt; {
  console.log('Server listening on port 3000');
});

The above code creates a basic Node.js server that listens on port 3000 and serves an HTML page. We can create the HTML page and add the Socket.IO client library as a script:

&lt;!DOCTYPE html&gt;
&lt;html&gt;
  &lt;head&gt;
    &lt;title&gt;Socket.IO Chat&lt;/title&gt;
    &lt;!-- Adding the Socket.IO client library --&gt;
    &lt;script src="/socket.io/socket.io.js"&gt;&lt;/script&gt;
  &lt;/head&gt;
  &lt;body&gt;
    &lt;div id="messages"&gt;&lt;/div&gt;
    &lt;input type="text" id="message"/&gt;
    &lt;button id="send"&gt;Send&lt;/button&gt;
    
    &lt;script&gt;
      //Initializing Socket.IO client
      const socket = io();
      
      //Getting the message element
      const messageElement = document.querySelector('#message');
      const sendButton = document.querySelector('#send');
      const messagesElement = document.querySelector('#messages');
      
      //Adding event listeners for when the send button is clicked
      sendButton.addEventListener('click', () =&gt; {
        const message = messageElement.value;
        socket.emit('message', message);
        messageElement.value = '';
      });
      
      //Handling incoming messages
      socket.on('message', (message) =&gt; {
        const messageElement = document.createElement('div');
        messageElement.textContent = message;
        messagesElement.appendChild(messageElement);
      });
    &lt;/script&gt;
  &lt;/body&gt;
&lt;/html&gt;

The above code initializes the Socket.IO client and adds event listeners to the send button. When clicked, the client emits a 'message' event to the server, which sends the message to all connected clients. When a client receives a 'message' event, the message is then displayed on the page.

Running the Chat Application

Now that we have created the basic Node.js server and HTML page, we can run the application by navigating to the project directory and running the following command in the terminal:

node app.js

Opening your browser and navigating to http://localhost:3000 will display the chat application. You can enter a message in the input field and click 'Send', and the message will be displayed for all connected clients.

Conclusion

In this tutorial, you have learned how to create a simple chat application using Socket.IO and Node.js. Socket.IO provides developers with a simple and powerful API for real-time communication, making it easy to create engaging, real-time features in web applications. With the knowledge gained in this tutorial, you now have the tools to incorporate Socket.IO into your own full-stack development projects.



<div>

<h1>Powerful Real-time Features with Socket.IO: Introductory Tutorial for Fullstack Developers</h1>

<p>In modern web development, real-time features are becoming increasingly popular. Whether it is for chat applications, notifications, or live updates, the ability to update your website or application in real-time has become a necessity. Socket.IO is one of the most popular libraries for real-time web applications, offering a simple, yet powerful solution for full-stack development. In this tutorial, we will guide you through creating a basic chat application using Socket.IO for real-time communication. </p>

<h2>What is Socket.IO?</h2>

<p>Socket.IO is a JavaScript library that enables real-time, bi-directional communication between the web clients and the server. It provides developers with a simple and powerful API that abstracts away the complexity of WebSocket and TCP protocols. The beauty of Socket.IO is its ability to work across different platforms, providing low-latency communication that's essential for real-time applications. </p>

<h2>Getting Started with Socket.IO</h2>

<p>The first step in using Socket.IO is to install the library. It's important to note that Socket.IO consists of two parts, one for the server and one for the client. In this tutorial, we will be using Node.js as our server, and the Socket.IO client will be included as a script in our HTML page.</p>

<pre><code class="language-bash">npm install socket.io</code></pre>

<p>Once installed, we can then create a basic Node.js server that will listen on a specific port and serve a basic HTML page:</p>

<pre><code class="language-javascript">//Importing the required modules
const http = require('http');
const fs = require('fs');
const path = require('path');

//Creating the HTTP server
const server = http.createServer((req, res) =&gt; {
  //Serving the basic HTML page
  if (req.url === '/') {
    fs.readFile(path.join(__dirname, 'index.html'), (err, data) =&gt; {
      if (err) {
        res.writeHead(500, { 'Content-Type': 'text/plain' });
        res.end('Internal Server Error');
      } else {
        res.writeHead(200, { 'Content-Type': 'text/html' });
        res.end(data);
      }
    });
  } else {
    res.writeHead(404, { 'Content-Type': 'text/plain' });
    res.end('Page Not Found');
  }
});

//Listening on port 3000
server.listen(3000, () =&gt; {
  console.log('Server listening on port 3000');
});</code></pre>

<p>The above code creates a basic Node.js server that listens on port 3000 and serves an HTML page. We can create the HTML page and add the Socket.IO client library as a script:</p>

<pre><code class="language-html">&lt;!DOCTYPE html&gt;
&lt;html&gt;
  &lt;head&gt;
    &lt;title&gt;Socket.IO Chat&lt;/title&gt;
    &lt;!-- Adding the Socket.IO client library --&gt;
    &lt;script src="/socket.io/socket.io.js"&gt;&lt;/script&gt;
  &lt;/head&gt;
  &lt;body&gt;
    &lt;div id="messages"&gt;&lt;/div&gt;
    &lt;input type="text" id="message"/&gt;
    &lt;button id="send"&gt;Send&lt;/button&gt;
    
    &lt;script&gt;
      //Initializing Socket.IO client
      const socket = io();
      
      //Getting the message element
      const messageElement = document.querySelector('#message');
      const sendButton = document.querySelector('#send');
      const messagesElement = document.querySelector('#messages');
      
      //Adding event listeners for when the send button is clicked
      sendButton.addEventListener('click', () =&gt; {
        const message = messageElement.value;
        socket.emit('message', message);
        messageElement.value = '';
      });
      
      //Handling incoming messages
      socket.on('message', (message) =&gt; {
        const messageElement = document.createElement('div');
        messageElement.textContent = message;
        messagesElement.appendChild(messageElement);
      });
    &lt;/script&gt;
  &lt;/body&gt;
&lt;/html&gt;</code></pre>

<p>The above code initializes the Socket.IO client and adds event listeners to the send button. When clicked, the client emits a 'message' event to the server, which sends the message to all connected clients. When a client receives a 'message' event, the message is then displayed on the page.</p>

<h2>Running the Chat Application</h2>

<p>Now that we have created the basic Node.js server and HTML page, we can run the application by navigating to the project directory and running the following command in the terminal:</p>

<pre><code class="language-bash">node app.js</code></pre>

<p>Opening your browser and navigating to <code>http://localhost:3000</code> will display the chat application. You can enter a message in the input field and click 'Send', and the message will be displayed for all connected clients.</p>

<h2>Conclusion</h2>

<p>In this tutorial, you have learned how to create a simple chat application using Socket.IO and Node.js. Socket.IO provides developers with a simple and powerful API for real-time communication, making it easy to create engaging, real-time features in web applications. With the knowledge gained in this tutorial, you now have the tools to incorporate Socket.IO into your own full-stack development projects.</p>

</div>

Discover how to create engaging, real-time features for your web applications by integrating Socket.IO, one of the most popular libraries for real-time web applications. This tutorial will guide you through setting up a basic chat application as a hands-on example of using Socket.IO in a fullstack web development project.

Powerful Real-time Features with Socket.IO: Introductory Tutorial for Fullstack Developers


  Effortlessly Deploy React Apps with Next.js and Azure Static Web Apps
  
  If you are a web developer, you know that the process of deploying applications can be a tedious, error-prone, and time-consuming task. In this article, we will explore a way to make deployment a breeze using Next.js and Azure Static Web Apps.

  What is Next.js?
  
  Next.js is a React framework that provides server-side rendering, making your React application faster and more SEO-friendly. It also offers other features, such as automatic code splitting, dynamic imports, and hot module reloading. Next.js is an excellent tool for building modern, high-performance, and scalable web applications.
  
  What are Azure Static Web Apps?
  
  Azure Static Web Apps is a service that allows you to easily deploy static web applications to the cloud. It provides built-in continuous integration and continuous delivery (CI/CD), automatic SSL, and custom domains. Azure Static Web Apps integrates seamlessly with GitHub, Azure DevOps, and Bitbucket.
  
  Getting Started with Next.js
  
  First, you need to install create-next-app, which is a global command-line interface (CLI) tool for creating new Next.js applications:
  
  npm install -g create-next-app
  
  Next, use the following command to create a new Next.js application called my-app:
  
  npx create-next-app my-app
  
  This will create a new directory called my-app with the basic structure of a Next.js application.
  
  Creating a new Azure Static Web App
  
  Now it is time to create a new Azure Static Web App. Go to the Azure portal and click on "Create a resource" in the top-left corner. Then, search for "Static Web App" and select it from the list of available resources.
  
  Next, fill out the required information, such as the subscription, resource group, and name of your new Azure Static Web App. Choose the operating system (Windows or Linux) and the runtime stack (Node.js or .NET). In this case, select Node.js as the runtime stack.
  
  After that, link your GitHub, Azure DevOps, or Bitbucket repository that contains your Next.js application. Choose the branch you want to deploy from and enter the build command that your application requires. Next.js applications need to run the build command to generate the optimized production build.
  
  Lastly, select a region close to your visitors to reduce latency.
  
  Once you have filled out all the required information, click on "Review + create" and then "Create" to start the deployment process.
  
  Configuring Azure Static Web Apps
  
  Now it is time to configure Azure Static Web Apps to work with your Next.js application. In the root directory of your Next.js application, create a new file called staticwebapp.config.json. This file contains the configuration settings for your Azure Static Web App.
  
  Here's an example of what the contents of the staticwebapp.config.json file should look like:
  
  {
    "routes": [
      {
        "route": "/*",
        "serve": "/out"
      }
    ],
    "navigationFallback": {
      "rewrite": "/index.html",
      "exclude": ["/api/*"]
    }
  }
  
  The routes array specifies that all requests should be redirected to the /out directory, which is where the Next.js build output resides. The navigationFallback object tells Azure Static Web Apps to rewrite all requests to the /index.html file, which is required for client-side routing to work properly, and excludes requests to any routes that start with /api/.
  
  Testing your Azure Static Web App
  
  After Azure Static Web Apps has finished deploying your Next.js application, you can test it by navigating to the URL provided by Azure. The URL should look like this:
  
  https://&lt;app-name&gt;.azurestaticapps.net
  
  If your application is working correctly, you should see your home page with no errors. You can also use the Azure portal to monitor your Azure Static Web App and view its logs.
  
  Conclusion
  
  That's it! You now know how to deploy a Next.js application effortlessly using Azure Static Web Apps. By leveraging Azure Static Web Apps, you can automate your deployment process and focus on building great applications instead of worrying about infrastructure. Happy coding!


<div>
  <h1>Effortlessly Deploy React Apps with Next.js and Azure Static Web Apps</h1>
  
  <p>If you are a web developer, you know that the process of deploying applications can be a tedious, error-prone, and time-consuming task. In this article, we will explore a way to make deployment a breeze using Next.js and Azure Static Web Apps.</p>

  <h2>What is Next.js?</h2>
  
  <p><b>Next.js</b> is a React framework that provides server-side rendering, making your React application faster and more SEO-friendly. It also offers other features, such as automatic code splitting, dynamic imports, and hot module reloading. Next.js is an excellent tool for building modern, high-performance, and scalable web applications.</p>
  
  <h2>What are Azure Static Web Apps?</h2>
  
  <p><b>Azure Static Web Apps</b> is a service that allows you to easily deploy static web applications to the cloud. It provides built-in continuous integration and continuous delivery (CI/CD), automatic SSL, and custom domains. Azure Static Web Apps integrates seamlessly with GitHub, Azure DevOps, and Bitbucket.</p>
  
  <h2>Getting Started with Next.js</h2>
  
  <p>First, you need to install <code>create-next-app</code>, which is a global command-line interface (CLI) tool for creating new Next.js applications:</p>
  
  <pre><code class="language-bash">npm install -g create-next-app</code></pre>
  
  <p>Next, use the following command to create a new Next.js application called <code>my-app</code>:</p>
  
  <pre><code class="language-bash">npx create-next-app my-app</code></pre>
  
  <p>This will create a new directory called <code>my-app</code> with the basic structure of a Next.js application.</p>
  
  <h2>Creating a new Azure Static Web App</h2>
  
  <p>Now it is time to create a new Azure Static Web App. Go to the <a href="https://portal.azure.com/">Azure portal</a> and click on "Create a resource" in the top-left corner. Then, search for "Static Web App" and select it from the list of available resources.</p>
  
  <p>Next, fill out the required information, such as the subscription, resource group, and name of your new Azure Static Web App. Choose the operating system (Windows or Linux) and the runtime stack (Node.js or .NET). In this case, select Node.js as the runtime stack.</p>
  
  <p>After that, link your GitHub, Azure DevOps, or Bitbucket repository that contains your Next.js application. Choose the branch you want to deploy from and enter the build command that your application requires. Next.js applications need to run the <code>build</code> command to generate the optimized production build.</p>
  
  <p>Lastly, select a region close to your visitors to reduce latency.</p>
  
  <p>Once you have filled out all the required information, click on "Review + create" and then "Create" to start the deployment process.</p>
  
  <h2>Configuring Azure Static Web Apps</h2>
  
  <p>Now it is time to configure Azure Static Web Apps to work with your Next.js application. In the root directory of your Next.js application, create a new file called <code>staticwebapp.config.json</code>. This file contains the configuration settings for your Azure Static Web App.</p>
  
  <p>Here's an example of what the contents of the <code>staticwebapp.config.json</code> file should look like:</p>
  
  <pre><code class="language-json">{
    "routes": [
      {
        "route": "/*",
        "serve": "/out"
      }
    ],
    "navigationFallback": {
      "rewrite": "/index.html",
      "exclude": ["/api/*"]
    }
  }</code></pre>
  
  <p>The <code>routes</code> array specifies that all requests should be redirected to the <code>/out</code> directory, which is where the Next.js build output resides. The <code>navigationFallback</code> object tells Azure Static Web Apps to rewrite all requests to the <code>/index.html</code> file, which is required for client-side routing to work properly, and excludes requests to any routes that start with <code>/api/</code>.</p>
  
  <h2>Testing your Azure Static Web App</h2>
  
  <p>After Azure Static Web Apps has finished deploying your Next.js application, you can test it by navigating to the URL provided by Azure. The URL should look like this:</p>
  
  <pre><code class="language-text">https://<code>&lt;app-name&gt;</code>.azurestaticapps.net</code></pre>
  
  <p>If your application is working correctly, you should see your home page with no errors. You can also use the Azure portal to monitor your Azure Static Web App and view its logs.</p>
  
  <h2>Conclusion</h2>
  
  <p>That's it! You now know how to deploy a Next.js application effortlessly using Azure Static Web Apps. By leveraging Azure Static Web Apps, you can automate your deployment process and focus on building great applications instead of worrying about infrastructure. Happy coding!</p>
</div>

Learn how to build and deploy a high-performance React application using Next.js and Azure Static Web Apps, enabling seamless continuous integration and continuous delivery.

Effortlessly Deploy React Apps with Next.js and Azure Static Web Apps


  Unlocking Real-time Communication: A Guide to WebSockets and Socket.IO for Fullstack Developers
  As web applications continue to evolve, the need for real-time communication between the server and the client becomes increasingly important. Whether it's a chat application or a stock trading platform, users expect instant updates and interactions. In this tutorial, we'll learn about WebSockets and Socket.IO and how they enable developers to implement real-time communication in their web applications. We'll explore practical examples and tips for fullstack developers looking to create highly interactive, data-driven applications.

  What are WebSockets?
  WebSockets are a protocol that enables two-way communication between a web browser and a server. Unlike traditional HTTP requests, which are unidirectional, WebSockets allow the server to push data to the client without the client first requesting it. This capability enables real-time, event-driven communication between the server and the client.

  WebSockets were introduced as a part of HTML5 specification and are supported by all modern web browsers. The WebSocket protocol is defined by IETF as RFC 6455. Below is an example of how a WebSocket connection is established:

  // create WebSocket instance
const ws = new WebSocket('wss://example.com/socket');

// WebSocket event listeners
ws.onopen = () => {
  console.log('WebSocket connection established');
};

ws.onmessage = (event) => {
  console.log(`Received message: ${event.data}`);
};

ws.onclose = () => {
  console.log('WebSocket connection closed');
};

  In the example above, we create a WebSocket instance and connect to the server using the URL wss://example.com/socket. We then define three event listeners: onopen which is triggered when the connection is established, onmessage which is triggered when a message is received from the server, and onclose which is triggered when the connection is closed.

  What is Socket.IO?
   Socket.IO is a library built on top of WebSockets that simplifies real-time communication between the server and the client. Socket.IO provides two-way communication channels between the server and each connected client, enabling real-time updates and interactions. 

  Socket.IO also provides fallback options, like XHR-polling and JSONP-polling, for older browsers that don't support WebSockets. Additionally, Socket.IO enables developers to create rooms, namespaces, and broadcast messages to specific groups of clients.

  Implementing Real-time Communication using Socket.IO
  Let's take a look at a practical example of using Socket.IO for a real-time chat application. We'll use Node.js for our server-side code and Angular for our client-side code.

  Server-side Code
  First, let's install the Socket.IO library in our Node.js project:

  npm install socket.io

  Next, we'll create our server-side code using Node.js and Socket.IO. Here's a simple example:

  const express = require('express');
const app = express();
const http = require('http').createServer(app);
const io = require('socket.io')(http);

// Socket.IO event listeners
io.on('connection', (socket) => {
  console.log('A user connected');

  // listen for message event
  socket.on('message', (data) => {
    console.log(`Received message: ${data}`);
    io.emit('message', data);
  });

  // listen for disconnect event
  socket.on('disconnect', () => {
    console.log('A user disconnected');
  });
});

// start server
http.listen(3000, () => {
  console.log('Server started on http://localhost:3000');
});

  In the code above, we create an HTTP server and a Socket.IO instance using Express.js and Node.js. We then define event listeners for when a client connects, disconnects, and sends a message. When a message is received, we log the message to the console and emit the message to all connected clients using io.emit() method.

  Client-side Code
  For our client-side code, we'll use Angular. We'll create a simple chat application with a form for users to enter their name and message:

  &lt;!-- index.html --&gt;
&lt;form #chatForm (ngSubmit)="sendMessage(chatForm.value)"&gt;
  &lt;input type="text" name="name" [(ngModel)]="name" placeholder="Your name" required&gt;
  &lt;input type="text" name="message" [(ngModel)]="message" placeholder="Type a message" required&gt;
  &lt;button type="submit"&gt;Send&lt;/button&gt;
&lt;/form&gt;

&lt;ul&gt;
  &lt;li *ngFor="let message of messages"&gt;
    {{ message.name }}: {{ message.text }}
  &lt;/li&gt;
&lt;/ul&gt;

  In the code above, we create a form with two input fields for the user to enter their name and message, and a button to submit the form. We also display all the messages received in a list using Angular's ngFor directive.

  Now let's create our Angular component and service:

  // chat.component.ts
import { Component } from '@angular/core';
import { ChatService } from './chat.service';

@Component({
  selector: 'app-chat',
  templateUrl: './chat.component.html',
  styleUrls: ['./chat.component.css']
})
export class ChatComponent {
  name: string;
  message: string;
  messages: { name: string, text: string }[] = [];

  constructor(private chatService: ChatService) {}

  ngOnInit() {
    this.chatService.connect();
    this.chatService.onMessage().subscribe((data) => {
      this.messages.push(data);
    });
  }

  sendMessage(form: any) {
    this.chatService.sendMessage({
      name: form.name,
      text: form.message
    });
    this.message = '';
  }
}

// chat.service.ts
import { Injectable } from '@angular/core';
import { Observable } from 'rxjs';
import { io } from 'socket.io-client';

@Injectable({
  providedIn: 'root'
})
export class ChatService {
  private socket: any;

  connect() {
    this.socket = io('http://localhost:3000');
  }

  disconnect() {
    this.socket.disconnect();
  }

  onMessage(): Observable {
    return new Observable((observer) => {
      this.socket.on('message', (data: any) => {
        observer.next(data);
      });
    });
  }

  sendMessage(message: any) {
    this.socket.emit('message', message);
  }
}

  In the code above, we create an Angular component ChatComponent and a service ChatService. The component displays the chat form and messages list, and the service connects to the WebSocket server and provides methods for sending and receiving messages.

  Now we're ready to start our Node.js server and Angular client. Run the following commands:

  node server.js
ng serve

  Open your web browser to http://localhost:4200 and try sending a message. You should see the message appear in the messages list in real-time, as shown below:

  

  Conclusion
  In this guide, we learned about WebSockets and Socket.IO and how they enable fullstack developers to implement real-time communication in their web applications. We explored a practical example of building a real-time chat application using Node.js and Angular. Socket.IO provides a simple and effective way to add real-time capabilities to web applications, enabling users to interact and receive updates instantly without having to refresh the page.


<div>
  <h1>Unlocking Real-time Communication: A Guide to WebSockets and Socket.IO for Fullstack Developers</h1>
  <p>As web applications continue to evolve, the need for real-time communication between the server and the client becomes increasingly important. Whether it's a chat application or a stock trading platform, users expect instant updates and interactions. In this tutorial, we'll learn about WebSockets and Socket.IO and how they enable developers to implement real-time communication in their web applications. We'll explore practical examples and tips for fullstack developers looking to create highly interactive, data-driven applications.</p>

  <h2>What are WebSockets?</h2>
  <p>WebSockets are a protocol that enables two-way communication between a web browser and a server. Unlike traditional HTTP requests, which are unidirectional, WebSockets allow the server to push data to the client without the client first requesting it. This capability enables real-time, event-driven communication between the server and the client.</p>

  <p>WebSockets were introduced as a part of HTML5 specification and are supported by all modern web browsers. The WebSocket protocol is defined by IETF as <a href="https://tools.ietf.org/html/rfc6455" target="_blank">RFC 6455</a>. Below is an example of how a WebSocket connection is established:</p>

  <pre lang="js"><code>// create WebSocket instance
const ws = new WebSocket('wss://example.com/socket');

// WebSocket event listeners
ws.onopen = () => {
  console.log('WebSocket connection established');
};

ws.onmessage = (event) => {
  console.log(`Received message: ${event.data}`);
};

ws.onclose = () => {
  console.log('WebSocket connection closed');
};</code></pre>

  <p>In the example above, we create a WebSocket instance and connect to the server using the URL <code>wss://example.com/socket</code>. We then define three event listeners: <code>onopen</code> which is triggered when the connection is established, <code>onmessage</code> which is triggered when a message is received from the server, and <code>onclose</code> which is triggered when the connection is closed.</p>

  <h2>What is Socket.IO?</h2>
  <p> Socket.IO is a library built on top of WebSockets that simplifies real-time communication between the server and the client. Socket.IO provides two-way communication channels between the server and each connected client, enabling real-time updates and interactions. </p>

  <p>Socket.IO also provides fallback options, like <code>XHR-polling</code> and <code>JSONP-polling</code>, for older browsers that don't support WebSockets. Additionally, Socket.IO enables developers to create rooms, namespaces, and broadcast messages to specific groups of clients.</p>

  <h2>Implementing Real-time Communication using Socket.IO</h2>
  <p>Let's take a look at a practical example of using Socket.IO for a real-time chat application. We'll use Node.js for our server-side code and Angular for our client-side code.</p>

  <h3>Server-side Code</h3>
  <p>First, let's install the Socket.IO library in our Node.js project:</p>

  <pre lang="bash"><code>npm install socket.io</code></pre>

  <p>Next, we'll create our server-side code using Node.js and Socket.IO. Here's a simple example:</p>

  <pre lang="js"><code>const express = require('express');
const app = express();
const http = require('http').createServer(app);
const io = require('socket.io')(http);

// Socket.IO event listeners
io.on('connection', (socket) => {
  console.log('A user connected');

  // listen for message event
  socket.on('message', (data) => {
    console.log(`Received message: ${data}`);
    io.emit('message', data);
  });

  // listen for disconnect event
  socket.on('disconnect', () => {
    console.log('A user disconnected');
  });
});

// start server
http.listen(3000, () => {
  console.log('Server started on http://localhost:3000');
});</code></pre>

  <p>In the code above, we create an HTTP server and a Socket.IO instance using Express.js and Node.js. We then define event listeners for when a client connects, disconnects, and sends a message. When a message is received, we log the message to the console and emit the message to all connected clients using <code>io.emit()</code> method.</p>

  <h3>Client-side Code</h3>
  <p>For our client-side code, we'll use Angular. We'll create a simple chat application with a form for users to enter their name and message:</p>

  <pre lang="html"><code>&lt;!-- index.html --&gt;
&lt;form #chatForm (ngSubmit)="sendMessage(chatForm.value)"&gt;
  &lt;input type="text" name="name" [(ngModel)]="name" placeholder="Your name" required&gt;
  &lt;input type="text" name="message" [(ngModel)]="message" placeholder="Type a message" required&gt;
  &lt;button type="submit"&gt;Send&lt;/button&gt;
&lt;/form&gt;

&lt;ul&gt;
  &lt;li *ngFor="let message of messages"&gt;
    {{ message.name }}: {{ message.text }}
  &lt;/li&gt;
&lt;/ul&gt;</code></pre>

  <p>In the code above, we create a form with two input fields for the user to enter their name and message, and a button to submit the form. We also display all the messages received in a list using Angular's <code>ngFor</code> directive.</p>

  <p>Now let's create our Angular component and service:</p>

  <pre lang="js"><code>// chat.component.ts
import { Component } from '@angular/core';
import { ChatService } from './chat.service';

@Component({
  selector: 'app-chat',
  templateUrl: './chat.component.html',
  styleUrls: ['./chat.component.css']
})
export class ChatComponent {
  name: string;
  message: string;
  messages: { name: string, text: string }[] = [];

  constructor(private chatService: ChatService) {}

  ngOnInit() {
    this.chatService.connect();
    this.chatService.onMessage().subscribe((data) => {
      this.messages.push(data);
    });
  }

  sendMessage(form: any) {
    this.chatService.sendMessage({
      name: form.name,
      text: form.message
    });
    this.message = '';
  }
}

// chat.service.ts
import { Injectable } from '@angular/core';
import { Observable } from 'rxjs';
import { io } from 'socket.io-client';

@Injectable({
  providedIn: 'root'
})
export class ChatService {
  private socket: any;

  connect() {
    this.socket = io('http://localhost:3000');
  }

  disconnect() {
    this.socket.disconnect();
  }

  onMessage(): Observable<any> {
    return new Observable<any>((observer) => {
      this.socket.on('message', (data: any) => {
        observer.next(data);
      });
    });
  }

  sendMessage(message: any) {
    this.socket.emit('message', message);
  }
}</code></pre>

  <p>In the code above, we create an Angular component <code>ChatComponent</code> and a service <code>ChatService</code>. The component displays the chat form and messages list, and the service connects to the WebSocket server and provides methods for sending and receiving messages.</p>

  <p>Now we're ready to start our Node.js server and Angular client. Run the following commands:</p>

  <pre lang="bash"><code>node server.js
ng serve</code></pre>

  <p>Open your web browser to <code>http://localhost:4200</code> and try sending a message. You should see the message appear in the messages list in real-time, as shown below:</p>

  <img src="https://user-images.githubusercontent.com/14102723/114285055-8c474c00-9a39-11eb-86a1-37a7d6e3ddbe.png" alt="Angular chat application screenshot">

  <h2>Conclusion</h2>
  <p>In this guide, we learned about WebSockets and Socket.IO and how they enable fullstack developers to implement real-time communication in their web applications. We explored a practical example of building a real-time chat application using Node.js and Angular. Socket.IO provides a simple and effective way to add real-time capabilities to web applications, enabling users to interact and receive updates instantly without having to refresh the page.</p>
</div>

Learn how to implement real-time communication in your web applications using WebSockets and Socket.IO. Discover practical examples and tips for fullstack developers looking to create highly interactive, data-driven applications.