Query to get Session/Subscriber count.

[marktani]

Issue by Plinpod Monday Jul 10, 2017 at 22:58 GMT Originally opened as https://github.com/graphcool/prisma/issues/307

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It would be handy to be able to query and/or subscribe to a count of the currently active sessions with the backend or a count of the current subscribers to a particular table filter.

[marktani]

Comment by kbrandwijk Monday Jul 10, 2017 at 23:07 GMT

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Some ideas to get the thought train going:

• Something like this on the server side (https://github.com/websockets/ws#how-to-detect-and-close-broken-connections), to deal with both 'normal' closes and disconnections
• Minimum functionality: a simple query that returns the count getWebsocketConnections { count }
• Preferably create hooks so we can attach our own functionality (onConnect, onClose, onDisconnect).
• Preferably allow passing some metadata to the websocket connection (subscription-transport-ws SubscriptionClient already has a connectionParams parameter that is sent to the server in the server-side onConnect event) so we can use this for grouping connections in our own function hooks, or use that to filter the query: getWebsocketConnection(filter: { metadata_contains: 'room=MyRoom' }) { count }
• Alternative: update some User field with the supplied metadata and a timestamp, but that wouldn't work for unauthenticated connections.

[marktani]

Comment by kbrandwijk Monday Jul 10, 2017 at 23:11 GMT

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A current workaround would be:

• Use the onConnect and onDisconnect events on the SubscriptionClient to execute some mutation
• Use a cron job to cleanup disconnected session for which a onDisconnect event didn't fire (browser closes, terminated connections, etc.)
• Use a middleware function on the client to fire a update mutation for a lastActive field on every query as a sort of 'keepAlive'

[marktani]

Comment by Plinpod Monday Jul 10, 2017 at 23:23 GMT

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In Socket.IO 1.4+ you can get this count like this

var room = io.sockets.adapter.rooms['my_room'];
room.length;

and I was hoping to replicate a similar functionality. It would allow for the most accurate client count.

[marktani]

Comment by marktani Monday Sep 18, 2017 at 09:50 GMT

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Related to https://github.com/graphcool/graphcool/issues/126