openvidu-js-node

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A secure OpenVidu sample app with a Node backend and a SPA frontend. It makes use of openvidu-node-client to connect to OpenVidu Server. With regard to the use of OpenVidu, it is identical to openvidu-mvc-node. This tutorial is intended for developers who feel more comfortable with a SPA (Single Page Application) architecture for their frontends.

Understanding this tutorial

OpenVidu is composed by the modules displayed on the image above.

  • openvidu-browser: JavaScript library for the browser. It allows you to manage your video-calls straight away from your clients
  • openvidu-node-client: server SDK for Node. Quick alternative to REST API
  • openvidu-server: application to control Kurento Media Server
  • Kurento Media Server: handles low level operations of media flow transmissions

Running this tutorial

1) Clone the repo:

git clone https://github.com/OpenVidu/openvidu-tutorials.git

2) You will need node to execute the app. You can install them with:

sudo curl -sL https://deb.nodesource.com/setup_8.x | sudo bash -
sudo apt-get install -y nodejs

3) Run the tutorial with the following commands. They will install the NPM dependencies and will execute server.js server passing two arguments: "localhost:4443" as the URL where openvidu-server will be listening and "MY_SECRET" as the secret share with it:

cd openvidu-tutorials/openvidu-js-node
npm install
node server.js localhost:4443 MY_SECRET

4) openvidu-server and Kurento Media Server must be up and running in your development machine. The easiest way is running this Docker container which wraps both of them (you will need Docker CE):

docker run -p 4443:4443 --rm -e openvidu.secret=MY_SECRET openvidu/openvidu-server-kms:2.6.0

5) Go to https://localhost:5000 to test the app once the server is running. The first time you use the docker container, an alert message will suggest you accept the self-signed certificate of openvidu-server when you first try to join a video-call. To test two users in the same computer, use a standard window and an incognito window.


If you are using Windows, read this FAQ to properly run the tutorial

To learn some tips to develop with OpenVidu, check this FAQ

Understanding the code

This is a very basic web application with a pretty simple JS/HTML/CSS frontend and a straightforward Node backend built with express. OpenVidu assumes you can identify your users so you can tell which users can connect to which video-calls, and what role (and therefore what permissions) each one of them will have in the calls. You can do this as you prefer. Here our backend will manage the users and their sessions with the easy-to-use and non-intrusive express-session API.

  • Backend: node server

    • server.js : single file which handles all operations of server

  • Frontend: Plain JS/HTML/CSS files (/public folder)

    • openvidu-browser-VERSION.js : openvidu-browser library. You don't have to manipulate this file.
    • app.js : sample application main JavaScritp file, which makes use of openvidu-browser-VERSION.js.
    • index.html : HTML code for the form to login, the form to connect to a video-call and for the video-call itself. It has two links to both JavaScript files:

      <script src="openvidu-browser-VERSION.js"></script>
      <script src="app.js"></script>
      
    • style.css: some CSS classes to style index.html.

Let's describe the code following this scenario: a user logs into the app and connects to the video-call "TUTORIAL", where he publishes his webcam. A second user will connect to the same video-call just after that and publish its own webcam. Both of them will leave the call after a while.


1) User logs in

We have implemented a method for making HTTP POST requests to the backend, as we will need to make at least three of them: one for logging in, one for getting a token from openvidu-server and one for letting know our backend when any user leaves the video-call. The header of the method looks like this:

function httpPostRequest(url, body, errorMsg, callback)

Where url is the path of the POST operation, body the object to send as data, errorMsg the output error message if something goes wrong and callback the function to execute in case of success. As mentioned above, we need to call this method three times for each user that LOGS IN ­číĺ CONNECTS TO A VIDEO-CALL ­číĺ LEAVES THE VIDEO-CALL.

index.html will first show a form to log in:

app.js sends a POST request to "/api-login/login" passing the username and the password retrieved from the HTML form whenever "Log in" button is clicked:

function logIn() {
    var user = $("#user").val(); // Username
    var pass = $("#pass").val(); // Password

    httpPostRequest(
        'api-login/login',
        {user: user, pass: pass},
        'Login WRONG',
        (response) => {
            // HTML shows logged-in page ...
        }
    );
}

server.js at /api-login/login checks the params are correct and if so sets an active session for the newly logged user (adding a loggedUser property with its username in the req.session object):

app.post('/api-login/login', function (req, res) {

    // Retrieve params from POST body
    var user = req.body.user;
    var pass = req.body.pass;

    if (login(user, pass)) { // Correct user-pass
        // Validate session and return OK
        // Value stored in req.session allows us to identify the user in future requests
        req.session.loggedUser = user;
        res.status(200).send();
    } else { // Wrong user-pass
        // Invalidate session and return error
        req.session.destroy();
        res.status(401).send('User/Pass incorrect');
    }
});

2) User connects to "TUTORIAL" video-call

HTML will display now the user has logged a different form, asking for the video-call to connect and the nickname the user wants to have in it. So our 'publisher1' user would write TUTORIAL in "Session" field and press "Join!" button:

app.js will execute joinSession() method, which starts like this:

function joinSession() {
    getToken((token) => { ...

So the first thing to do here is to retrieve an OpenVidu token from our backend. Only when we have it available in the browser we will continue with the join operation. Let's see what getToken() looks like:

function getToken(callback) {
    sessionName = $("#sessionName").val(); // Video-call chosen by the user

    httpPostRequest(
        'api-sessions/get-token',
        {sessionName: sessionName},
        'Request of TOKEN gone WRONG:',
        (response) => {
            token = response[0]; // Get token from response
            console.warn('Request of TOKEN gone WELL (TOKEN:' + token + ')');
            callback(token); // Continue the join operation
        }
    );
}

Here is the second time we must call our httpPostRequest() method, sending the session we want to connect (sessionName parameter) and waiting to get a token as response. The interesting part here is in server.js controller at /api-sessions/get-token. First of all there are some important attributes in this class we must mention:

// Environment variable: URL where our OpenVidu server is listening
var OPENVIDU_URL = process.argv[2];
// Environment variable: secret shared with our OpenVidu server
var OPENVIDU_SECRET = process.argv[3];

// Entrypoint to OpenVidu Node Client SDK
var OV = new OpenVidu(OPENVIDU_URL, OPENVIDU_SECRET);

// Collection to pair session names with OpenVidu Session objects
var mapSessions = {};
// Collection to pair session names with tokens
var mapSessionNamesTokens = {};

Rest controller method begins retrieving the param send by the client, which in this case is the video-call name ("TUTORIAL"), as well as preparing a param we will need a little further on: tokenOptions.

app.post('/api-sessions/get-token', function (req, res) {

   // ... check the user is logged with req.session and continue ...

    // The video-call to connect ("TUTORIAL")
    var sessionName = req.body.sessionName;

    // Role associated to this user
    var role = users.find(u => (u.user === req.session.loggedUser)).role;

    // Optional data to be passed to other users when this user connects to the video-call
    // In this case, a JSON with the value we stored in the req.session object on login
    var serverData = JSON.stringify({serverData: req.session.loggedUser});

    // Build tokenOptions object with the serverData and the role
    var tokenOptions = {
        data: serverData,
        role: role
    };

Just after that an if-else statement comes into play: does the session "TUTORIAL" already exist?

if (mapSessions[sessionName]) { ...

In this case it doesn't because 'publisher1' is the first user connecting to it. So we focus on the else branch:

else {
    // New session
    console.log('New session ' + sessionName);

    // Create a new OpenVidu Session asynchronously
    OV.createSession()
        .then(session => {
            // Store the new Session in the collection of Sessions
            mapSessions[sessionName] = session;
            // Store a new empty array in the collection of tokens
            mapSessionNamesTokens[sessionName] = [];

            // Generate a new token asynchronously with the recently created tokenOptions
            session.generateToken(tokenOptions)
                .then(token => {

                    // Store the new token in the collection of tokens
                    mapSessionNamesTokens[sessionName].push(token);

                    // Return the Token to the client
                    res.status(200).send({
                        0: token
                    });
                })
                .catch(error => {
                    console.error(error);
                });
        })
        .catch(error => {
            console.error(error);
        });
}

We are almost there! Now in app.js we can init a new Session and connect to it with token:

// --- 1) Get an OpenVidu object ---

OV = new OpenVidu();

// --- 2) Init a session ---

session = OV.initSession();

// --- 3) Specify the actions when events take place in the session ---

// On every new Stream received...
session.on('streamCreated', (event) => {

    // Subscribe to the Stream to receive it
    // HTML video will be appended to element with 'video-container' id
    var subscriber = session.subscribe(event.stream, 'video-container');

    // When the HTML video has been appended to DOM...
    subscriber.on('videoElementCreated', (event) => {

        // Add a new HTML element for the user's name and nickname over its video
        appendUserData(event.element, subscriber.stream.connection);
    });
});

// On every Stream destroyed...
session.on('streamDestroyed', (event) => {
    // Delete the HTML element with the user's name and nickname
    removeUserData(event.stream.connection);
});

// --- 4) Connect to the session passing the retrieved token and some more data from
//        the client (in this case a JSON with the nickname chosen by the user) ---

var nickName = $("#nickName").val();
session.connect(token, { clientData: nickName })
    .then(() => {

        // --- 5) Set page layout for active call ---

        var userName = $("#user").val();
        $('#session-title').text(sessionName);
        $('#join').hide();
        $('#session').show();


        // Here we check somehow if the user has 'PUBLISHER' role before
        // trying to publish its stream. Even if someone modified the client's code and
        // published the stream, it wouldn't work if the token sent in Session.connect
        // method is not recognized as 'PUBLIHSER' role by OpenVidu Server
        if (isPublisher(userName)) {

            // --- 6) Get your own camera stream ---

            var publisher = OV.initPublisher('video-container', {
                audioSource: undefined, // The source of audio. If undefined default microphone
                videoSource: undefined, // The source of video. If undefined default webcam
                publishAudio: true,     // Whether you want to start publishing with your audio unmuted or not
                publishVideo: true,     // Whether you want to start publishing with your video enabled or not
                resolution: '640x480',  // The resolution of your video
                frameRate: 30,          // The frame rate of your video
                insertMode: 'APPEND',   // How the video is inserted in the target element 'video-container'
                mirror: false           // Whether to mirror your local video or not
            });

            // --- 7) Specify the actions when events take place in our publisher ---

            // When our HTML video has been added to DOM...
            publisher.on('videoElementCreated', (event) => {
                // Init the main video with ours and append our data
                var userData = {
                    nickName: nickName,
                    userName: userName
                };
                initMainVideo(event.element, userData);
                appendUserData(event.element, userData);
                $(event.element).prop('muted', true); // Mute local video
            });


            // --- 8) Publish your stream ---

            session.publish(publisher);

        } else {
            console.warn('You don\'t have permissions to publish');
            initMainVideoThumbnail(); // Show SUBSCRIBER message in main video
        }
    })
    .catch(error => {
        console.warn('There was an error connecting to the session:', error.code, error.message);
    });

The user will now see its own video on the page. The connection to the session has completed!


3) Another user connects to the video-call

The process would be exactly the same as before until server.js executes controller at /api-sessions/get-token. Now session 'TUTORIAL' already exists, so in the if-else statement the if branch would be the one executed:

if (mapSessions[sessionName]) {
    // Session already exists
    console.log('Existing session ' + sessionName);

    // Get the existing Session from the collection
    var mySession = mapSessions[sessionName];

    // Generate a new token asynchronously with the recently created tokenOptions
    mySession.generateToken(tokenOptions)
        .then(token => {

            // Store the new token in the collection of tokens
            mapSessionNamesTokens[sessionName].push(token);

            // Return the token to the client
            res.status(200).send({
                0: token
            });
        })
        .catch(error => {
            console.error(error);
        });
}

The code executed in app.js would also be the same. After the Session.publish() method has been successful, both users will be seeing each other's video, as well as the username and nickname uppon it.


4) Users leave the video-call

After a while both users decide to leave the session. Apart from calling leaveSession() (and therefore session.disconnect()) to destroy the connection on OpenVidu Server, we need to run the last POST operation: we must let the backend know that certain user has left the session so it can update the collections with the active sessions and tokens. To sum up, session.disconnect() updates our OpenVidu Server and the POST operation updates our application's backend. For the POST operation, in app.js we run:

function removeUser() {
    httpPostRequest(
        'api-sessions/remove-user',
        {sessionName: sessionName, token: token},
        'User couldn\'t be removed from session', 
        (response) => {
            console.warn("You have been removed from session " + sessionName);
        }
    );
}

And in server.js we update the collections in /api-sessions/remove-user:


app.post('/api-sessions/remove-user', function (req, res) {

    // ... check the user is logged with req.session and continue ...

    // Retrieve params from POST body
    var sessionName = req.body.sessionName;
    var token = req.body.token;

    // If the session exists
    if (mapSessions[sessionName] && mapSessionNamesTokens[sessionName]) {
        var tokens = mapSessionNamesTokens[sessionName];
        var index = tokens.indexOf(token);

        // If the token exists
        if (index !== -1) {
            // Token removed
            tokens.splice(index, 1);
        } else {
            res.status(500).send('Problems in the app server: the TOKEN wasn\'t valid');
        }
        if (tokens.length == 0) {
            // Last user left: session must be removed
            delete mapSessions[sessionName];
        }
        res.status(200).send();
    } else {
        res.status(500).send('Problems in the app server: the SESSION does not exist');
    }
});

When the last user leaves the session delete mapSessions[sessionName] will be executed: this means the session is empty and that it has been closed in OpenVidu Server. All our Session objects and tokens associated to them will be invalidated.


At this point we have covered all the important code from the tutorial. With this scenario we have seen the most common use-case, but you can modify whatever you want to suit your needs. And remember that this is just one of the many possible approaches: you can implement your frontend and your backend as you want.

The only actual requirements are getting a valid token from openvidu-server (by using openvidu-java-client, openvidu-node-client or the REST API) and use it in openvidu-browser to connect your clients to the sessions with Session.connect(token)