based on post Redux WebSocket Integration

Client Redux Middleware

• subscribe on all ws message, extract type and payload from it and match type to existing actions types. If it matches dispatch the action with payload
• on special emit actions emit ws event to server (so server could hold your state and fire needed events back to you)

Server Side

• Q: how to store user's state?
• Q: how to use user's state and subscribe to something else and emit ws back to client?
• Q: isn't it make fat server?

from fire-marshal.

based on https://github.com/notgiorgi/redux-websocket-middleware

• create connection manager (https://github.com/notgiorgi/redux-websocket-middleware/blob/master/src/lib/ConnectionManager.js)
  • uses redux store to emit events on open, close, error, receive message events (https://github.com/notgiorgi/redux-websocket-middleware/blob/master/src/actions.js)
  • queue of messages
  • could connect with multiple endpoints (specific endpoint is sent in meta option)
• use native WebSocket
• emit to server by adding extra option meta: { socket: true }

from fire-marshal.

based on https://github.com/cape-io/cape-redux-socket/

• cookie middleware

from fire-marshal.

the most popular https://github.com/itaylor/redux-socket.io and one of the simplest solution.

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Server side Agent

• receives users data (input)
• store data (MongoDB)
• react on new data (subscribe to something)
• gets data from something
• send ws messages back to client
  in other words it is simplified version of user but on server side

Important

• scalability - we can't use server state, only state from DB
• what will be in case of restarted server? Do use would need to send all needed information again? Or we could recreated from DB?

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Few types of client state

consistent

• important only the last state (doesn't care about history) we don't need queue here
• example: user's location, watching streaming data
• on lost connection/reconnect: preserve and send this state to server

coherent

• important all history (queue)
• example: user's messages
• on lost connection/reconnect: preserve queue and send whole queue to server

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