Integrated sync backend

[juliushaertl]

Now that we have the basic sync running with the websocket_server, we should look into how we can mirror the behaviour with a PHP-only backend.

socket.io supports long polling https://socket.io/docs/v3/how-it-works/#http-long-polling which we could make use of

• [ ] provide php endpoints for GET and POST requests
• [ ] Think about way to store/distribute and handle the messages
  • [ ] server-to-client
  • [ ] init-room
  • [ ] joined-data
  • [ ] first-in-room
  • [ ] room-user-change
  • [ ] client-broadcast
  • [ ] user-follow-room-change
  • [ ] room-user-change
  • [ ] broadcast-unfollow
  • [ ] client-to-server
  • [ ] connection init
  • [ ] join-room
  • [ ] server-broadcast
  • [ ] server-volatile-broadcast
  • [ ] user-follow
  • [ ] disconnecting
  • [ ] disconnect

We could potentially require redis with https://github.com/phpredis/phpredis?tab=readme-ov-file#publish or just use a db backend if that is not present.

Required protocols to implement https://github.com/socketio/engine.io-protocol https://socket.io/docs/v4/socket-io-protocol#introduction

Additional resources https://github.com/socketIo-php https://github.com/socketIo-php/engine.io-parser https://github.com/socketIo-php/socket.io-parser

[juliushaertl]

We might go with just using https://github.com/cloud-py-api/app_api for easy deployment of the node backend.

• [ ] Check if we can easily spin up the existing image from #82
• [ ] service inside ExApp can be accessed through App API proxy(apps/app_api/proxy/whiteboard/some_url) - will it be enough to use longpolling with socket.io
• [ ] otherwise evaluate effort for proxying websocket connections automatically with https://cloud-py-api.github.io/app_api/DeployConfigurations.html#docker-deploy-daemon