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/**
* The WebSocket backend is responsible for updating our knowledge of flows and events
* from the REST API and live updates delivered via a WebSocket connection.
* An alternative backend may use the REST API only to host static instances.
*/
import { fetchApi } from "../utils"
import * as connectionActions from "../ducks/connection"
const CMD_RESET = 'reset'
export default class WebsocketBackend {
constructor(store) {
this.activeFetches = {}
this.store = store
this.connect()
}
connect() {
this.socket = new WebSocket(location.origin.replace('http', 'ws') + '/updates')
this.socket.addEventListener('open', () => this.onOpen())
this.socket.addEventListener('close', event => this.onClose(event))
this.socket.addEventListener('message', msg => this.onMessage(JSON.parse(msg.data)))
this.socket.addEventListener('error', error => this.onError(error))
}
onOpen() {
this.fetchData("settings")
this.fetchData("flows")
this.fetchData("events")
this.fetchData("options")
this.store.dispatch(connectionActions.startFetching())
}
fetchData(resource) {
let queue = []
this.activeFetches[resource] = queue
fetchApi(`./${resource}`)
.then(res => res.json())
.then(json => {
// Make sure that we are not superseded yet by the server sending a RESET.
if (this.activeFetches[resource] === queue)
this.receive(resource, json)
})
}
onMessage(msg) {
if (msg.cmd === CMD_RESET) {
return this.fetchData(msg.resource)
}
if (msg.resource in this.activeFetches) {
this.activeFetches[msg.resource].push(msg)
} else {
let type = `${msg.resource}_${msg.cmd}`.toUpperCase()
this.store.dispatch({ type, ...msg })
}
}
receive(resource, data) {
let type = `${resource}_RECEIVE`.toUpperCase()
this.store.dispatch({ type, cmd: "receive", resource, data })
let queue = this.activeFetches[resource]
delete this.activeFetches[resource]
queue.forEach(msg => this.onMessage(msg))
if(Object.keys(this.activeFetches).length === 0) {
// We have fetched the last resource
this.store.dispatch(connectionActions.connectionEstablished())
}
}
onClose(closeEvent) {
this.store.dispatch(connectionActions.connectionError(
`Connection closed at ${new Date().toUTCString()} with error code ${closeEvent.code}.`
))
console.error("websocket connection closed", closeEvent)
}
onError() {
// FIXME
console.error("websocket connection errored", arguments)
}
}
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