openvidu-browser: NPM package for your Angular app. It allows you to manage your video-calls straight away from your clients
openvidu-server: Java application that controls Kurento Media Server
Kurento Media Server: server that handles low level operations of media flow transmissions

You will only have to make use of openvidu-browser NPM package to get this sample app working

Executing this example

Clone the repo:

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

You will need angular-cli to serve the Angular frontend. You can install it with the following command:
```
npm install -g @angular/cli
```
To run the sample application, execute the following command in the project:
```
cd openvidu-insecure-angular
npm install
ng serve
```
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 8443:8443 --rm -e KMS_STUN_IP=193.147.51.12 -e KMS_STUN_PORT=3478 -e openvidu.security=false openvidu/openvidu-server-kms
```
Go to localhost:4200 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.

Understanding the code

This is an Angular project generated with angular-cli, and therefore you will see lots of configuration files and other stuff that doesn't really matter to us. After getting openvidu-browser NPM package (npm install openvidu-browser), we will focus on the following files under src/app/ folder:

app.component.ts: AppComponent, main component of the app. It contains the functionalities for joining a video-call and for handling the video-calls themselves.
app.component.html: HTML for AppComponent.
app.component.css: CSS for AppComponent.
stream.component.css: StreamComponent, auxiliary component to manage Stream objects on our own. It wraps the final HTML <video> which will display the video of its Stream property, as well as the user's nickname in a <p> element.

Let's see how app.component.ts uses openvidu-browser:

First line imports the necessary objects from openvidu-browser:

import { OpenVidu, Session, Stream } from 'openvidu-browser';

app.component.ts declares the following properties:
```
// OpenVidu objects
OV: OpenVidu;
session: Session;

// Streams to feed StreamComponent's
remoteStreams: Stream[] = [];
localStream: Stream;

// Join form
sessionId: string;
token: string;
```
OpenVidu object will allow us to get a Session object, which is declared just after it. remoteStreams array will store the active streams of other users in the video-call and localStream will be your own local webcam stream. Finally, sessionId and token params simply represent the video-call and your participant's nickname, as you will see in a moment.
Whenever a user clicks on the submit input defined in app.component.html, joinSession() method is called:
```
this.OV = new OpenVidu('wss://' + location.hostname + ':8443/');
this.session = this.OV.initSession('apikey', this.sessionId);
```
Since we are in a local sample app, OV is initialize with localhost:8443 as its openvidu-server URL. session is initialize with sessionId param: this means we will connect to sessionId video-call. In this case, this parameter is binded from an <input> element of app.component.html, which may be filled by the user.
```
this.session.on('streamCreated', (event) => {
  this.remoteStreams.push(event.stream); // Add the new stream to 'remoteStreams' array
  this.session.subscribe(event.stream, ''); // Empty string for no video element
});

this.session.on('streamDestroyed', (event) => {
  event.preventDefault(); // Avoid OpenVidu trying to remove the HTML video element
  this.deleteRemoteStream(event.stream); // Remove the stream from 'remoteStreams' array
});
```
Here we subscribe to the Session events that interest us. As we are using Angular framework, a good approach will be treating each Stream as a component, contained in a StreamComponent. Thus, we need to store each new stream we received in an array (remoteStreams), and we must remove from it every deleted stream whenever it is necessary. To achieve this, we use the following events:
- streamCreated: for each new Stream received by OpenVidu, we store it in our remoteStreams array and immediately subscribe to it so we can receive its video (empty string as second parameter, so OpenVidu doesn't create an HTML video on its own). HTML template of AppComponent will show the new video, as it contains an ngFor directive which will create a new StreamComponent for each Stream object stored in the array:
```
<div id="subscriber">
 	<div *ngFor="let s of this.remoteStreams">
 		<stream-component [stream]="s"></stream-component>
 	</div>
 </div>
```
- streamDestroyed: for each Stream that has been destroyed (which means a user has left the video-call), we remove it from remoteStreams array, so Angular will automatically delete the required StreamComponent from HTML. We call event.preventDefault() to cancel OpenVidu default behaviour towards streamDestroyed event, which is the deletion of the previously created HTML video element on streamCreated event. Because we are handling the video elements by ourselves taking advantage of Angular capabilities, we tell OpenVidu not to create them on streamCreated and not to delete them on streamDestroyed, by passing an empty string as second parameter on Session.subscribe() method on streamCreated and by calling event.preventDefault() on streamDestroyed.
Finally connect to the session and publish your webcam:
```
this.session.connect(this.token, '{"clientData": "' + this.token + '"}', (error) => {
  // If the connection is successful, initialize a publisher and publish to the session
  if (!error) {

    // 4) Get your own camera stream with the desired resolution and publish it
    let publisher = this.OV.initPublisher('', {
      audio: true,
      video: true,
      quality: 'MEDIUM'
    });

    this.localStream = publisher.stream;

    // 5) Publish your stream
    this.session.publish(publisher);

  } else {
    console.log('There was an error connecting to the session:', error.code, error.message);
  }
});
```
token param is irrelevant when using insecure version of OpenVidu. Second parameter will supply the user's nickname showed by StreamComponent inside its <p> element. So in this case it is a JSON formatted string with a "clientData" tag with "token" value, which is retrieved from HTML input <input type="text" name="token" id="token" [(ngModel)]="token" required> (filled by the user).

In the callback of Session.connect method, we check the connection has been succesful (error value must be null) and right after that we get a Publisher object with both audio and video activated and MEDIUM quality. We then store our local Stream (contained in Publisher.stream object) in localStream and publish the Publisher object through Session.publish() method. The rest of users will receive our Stream object and will execute their streamCreated event.

With regard to our local Stream, AppComponent's HTML template has also one StreamComponent declaration ready to show our own webcam as we did with remote streams:
```
<div id="publisher">
	<div *ngIf="this.localStream">
		<stream-component [stream]="this.localStream"></stream-component>
	</div>
</div>
```
Last point worth considering is the ngDoCheck() implementation of StreamComponent. As we are handling Stream objects by ourselves (task which usually is taken care by OpenVidu), and because the URL of Stream objects takes some time to get its final value as the WebRTC negotiation takes place, we must listen to any change in stream @Input property. This allows us to update videoSrc value of the component, which finally ends up being the src value of the <video> element. If we didn't do this, the Stream object will update its src property, but our StreamComponent would keep the same initial videoSrc value. This ensures that all our StreamComponent's will properly display all the videos in the video-call using the correct src value.
```
ngDoCheck() { // Detect any change in 'stream' property
    // If 'src' of Stream object has changed, 'videoSrc' value must be updated
    if (!(this.videSrcUnsafe === this.stream.getVideoSrc())) {
        // Angular mandatory URL sanitization
        this.videoSrc = this.sanitizer.bypassSecurityTrustUrl(this.stream.getVideoSrc());
        // Auxiliary value to store the URL as a string for upcoming comparisons
        this.videSrcUnsafe = this.stream.getVideoSrc();
    }
}
```