wsss
v1.0.1
Published
websocket shared-state server
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#WSSS - Websocket Shared State Simple websocket server that allows clients to subscribe to updates and arbitrarily update a shared JSON blob.
Quick start
From command line:
npm install
npm start [PORT_NUMBER] # defaults to 8000
From nodejs
require('wsss')(PORT_NUMBER) // defaults to 8000
How it works
Client randomly generates an id for itself, and connects to a named 'room' by sending a ws message like:
{ "id": "af5ef05ebab5447b71be9"
, "roomName": "room 101"
}
If the room already exists, then the current state of the room will be sent back to the client. For example
{ "name": "room 101"
, "version": "ec10de375cd3be59"
, "state":
{ "arbitrary": "json"
, "that": ["somebody put here", "previously"]
}
}
If the room does not exist, it will be created and the state will be initialized to an empty JSON object. For example:
{ "name": "room 101"
, "version": "91efca9fabc35bee"
, "state": {}
}
To update the state, send your id, the roomName, the current 'version' of the room, and an 'update', a JSON blob to replace the current state.
{ "id": "af5ef05ebab5447b71be9"
, "roomName": "room 101"
, "version": "91efca9fabc35bee"
, "update": { "message": "Richard was here" }
}
If the provided version matches the version on the server, a new 'version' will be randomly generated and the new state will be sent to all clients who have connected to the room.
{ "name" : "room 101"
, "version": "cf2e7131ffbac447"
, "state": { "message": "Richard was here" }
}
If the provided version doesn't match, the state will not be updated and an error will be sent to the client which attempted the update, along with the most up-to-date state/version of the room.
{ "error": "wrong version"
, "data":
{ "name" : "room 101"
, "version": "70a729dd590bb8b5"
, "state": { "message": "Griselda was here before Richard. Nya nya."}
}
}
That's it!