Stream Broker

This micro service implments business rules for a video stream server.

This service checks how many video streams a given user is watching and prevents a user watching more than 3 video streams concurrently.

This service does not implement any UI as such. It provides backend support for following functions for the accompanying UI:

• provides a list of available video to stream
• maintains a list of video streams being actively played by a user
  • start a stream
  • stop a stream
• possibly expire an active stream after duration of the stream

$ git clone rehangit/streambroker.git
$ cd streambroker
$ npm start

This microservice can be deployed to now by Zeit. Assuming you've got now installed and set up:

$ now rehangit/streambroker

One of the instance running on now: https://streambroker-uqidgkqhpc.now.sh/

Try https://streambroker-uqidgkqhpc.now.sh/videos to see some sample data

Using a JWT token (as explain below) you can use Postman to GET https://streambroker-uqidgkqhpc.now.sh/streams to list a user streams POST https://streambroker-uqidgkqhpc.now.sh/streams/video/:videoId start streaming a video DELETE https://streambroker-uqidgkqhpc.now.sh/streams/:streamId stop/remove a streaming video

Alternative, deploy right now without even leaving the browser:

This microservice is also deployable on heroku using the config included.

/videos 
  GET (public) - lists all available videos to stream

/streams
  GET (user) - lists videoIds for all active video streams being played by the user 
  
/streams/video/:videoId
  POST (user) - generates and returns the short lived stream url for the video associated with videoId. This stream is counted towards the active video streams being watched by the user until manually removed or expires

/streams/:streamId 
  DELETE (user) - removes streamId from the current list of streams for user

The service maintains database of following models

video {
  id,
  name,
  confidentialLink
};

stream {
  id,
  userId,
  videoId,      
  transientLink,
  createdAt,
};

Only signed users can access the user API except GET /video which is public. A signed user is one with JWT Bearer token that is signed with a secret (default: secret123). The following info is expected in the token:

Header: { "typ": "JWT", "alg": "HS256" }

Payload: { "sub": "user_id", "iat": "timestamp" }

(e.g. { "sub": "user_xyz", "iat": 1529888559 })

An example token:

eyJ0eXAiOiJKV1QiLCJhbGciOiJIUzI1NiJ9.eyJzdWIiOiJ1c2VyX3h5eiIsImlhdCI6MTUyOTg4ODU1OSwianRpIjoiNmZjYjBkZjMtYmU1Yy00NzJlLThjOTItYTczYjZhNWVkOGIzIiwiZXhwIjoxNTI5ODkyMTY1fQ.olRWZqpUnedb3jVxz_a81NeHnEEgWg9mCcAqz9NOPfw

When a stream is created for a signed in user against a videoId, a transientLink is generated to play the video. This link is mapped to the confidentialLink of the video which is normally not directly accessible.

Current raw implementation exposes the video.confidentialLink directly in the stream.transientLink, however a future improvement can be implmented to issue a short lived signed JWT token containing the videoId or the video confidential link. In this scenario when the user would request to play the stream the token could be decoded and played if still valid. Otherwise the stream would be considered to have expired and would be removed from the user's current list of playing streams.

MIT © Rehan Ahmad