ShareDB：构建实时应用从未如此简单

var express = require('express')
var WebSocket = require('ws')
var http = require('http')
var ShareDB = require('sharedb')
var WebSocketJSONStream = require('@teamwork/websocket-json-stream')
var app = express()
var server = http.createServer(app)
var webSocketServer = WebSocket.Server({server: server})
var backend = new ShareDB()
webSocketServer.on('connection', (webSocket) => {
  var stream = new WebSocketJSONStream(webSocket)
  backend.listen(stream)
})
server.listen(8080)

var ReconnectingWebSocket = require('reconnecting-websocket')
var Connection = require('sharedb/lib/client').Connection
var socket = new ReconnectingWebSocket('ws://localhost:8080', [], {
  // ShareDB handles dropped messages, and buffering them while the socket
  // is closed has undefined behavior
  maxEnqueuedMessages: 0
})
var connection = new Connection(socket)
var doc = connection.get('doc-collection', 'doc-id')
doc.subscribe((error) => {
  if (error) return console.error(error)
  // If doc.type is undefined, the document has not been created, so let's create it
  if (!doc.type) {
    doc.create({counter: 0}, (error) => {
      if (error) console.error(error)
    })
  }
});
doc.on('op', (op) => {
  console.log('count', doc.data.counter)
})
window.increment = () => {
  // Increment the counter by 1
  doc.submitOp([{p: ['counter'], na: 1}])
}

const backend = new Backend({
  db: new MemoryDB(),
})

const backend = new Backend({
  pubsub: new MemoryPubSub(),
})