| 1 |
|
| 2 |
|
| 3 |
const GQL = { |
| 4 |
CONNECTION_INIT: 'connection_init', |
| 5 |
CONNECTION_ACK: 'connection_ack', |
| 6 |
CONNECTION_ERROR: 'connection_error', |
| 7 |
CONNECTION_KEEP_ALIVE: 'ka', |
| 8 |
START: 'start', |
| 9 |
STOP: 'stop', |
| 10 |
CONNECTION_TERMINATE: 'connection_terminate', |
| 11 |
DATA: 'data', |
| 12 |
ERROR: 'error', |
| 13 |
COMPLETE: 'complete' |
| 14 |
} |
| 15 |
|
| 16 |
class Subscriber { |
| 17 |
constructor (url, options, callback, protocols = 'graphql-ws') { |
| 18 |
this.callback = callback |
| 19 |
|
| 20 |
this.nextId = 1 |
| 21 |
this.subscriptions = new Map() |
| 22 |
this.webSocket = new WebSocket(url, protocols) |
| 23 |
|
| 24 |
this.webSocket.onopen = event => { |
| 25 |
// Initiate the connection |
| 26 |
this.webSocket.send(JSON.stringify({ |
| 27 |
type: GQL.CONNECTION_INIT, |
| 28 |
payload: options |
| 29 |
})) |
| 30 |
|
| 31 |
setInterval(function () { |
| 32 |
this.webSocket.send(JSON.stringify({ |
| 33 |
type: GQL.CONNECTION_KEEP_ALIVE |
| 34 |
})) |
| 35 |
}.bind(this), 5000); |
| 36 |
} |
| 37 |
|
| 38 |
|
| 39 |
this.webSocket.onclose = event => { |
| 40 |
// The code 1000 (Normal Closure) is special, and results in no error or payload. |
| 41 |
const error = event.code === 1000 ? null : new Error(event) |
| 42 |
// Notify the subscriber. |
| 43 |
this.callback(error) |
| 44 |
// Notify the subscriptions. |
| 45 |
const callbacks = Array.from(this.subscriptions.values()) |
| 46 |
this.subscriptions.clear() |
| 47 |
for (const callback of callbacks) { |
| 48 |
callback(error, null) |
| 49 |
} |
| 50 |
} |
| 51 |
|
| 52 |
this.webSocket.onmessage = this.onMessage.bind(this) |
| 53 |
} |
| 54 |
|
| 55 |
subscribe (query, variables, operationName, callback) { |
| 56 |
const id = (this.nextId++).toString() |
| 57 |
this.subscriptions.set(id, callback) |
| 58 |
|
| 59 |
this.webSocket.send(JSON.stringify({ |
| 60 |
type: GQL.START, |
| 61 |
id, |
| 62 |
payload: { query, variables, operationName } |
| 63 |
})) |
| 64 |
|
| 65 |
// Return the unsubscriber. |
| 66 |
return () => { |
| 67 |
this.subscriptions.delete(id) |
| 68 |
|
| 69 |
this.webSocket.send(JSON.stringify({ |
| 70 |
type: GQL.STOP, |
| 71 |
id |
| 72 |
})) |
| 73 |
} |
| 74 |
} |
| 75 |
|
| 76 |
shutdown () { |
| 77 |
this.webSocket.send(JSON.stringify({ |
| 78 |
type: GQL.CONNECTION_TERMINATE |
| 79 |
})) |
| 80 |
this.webSocket.close() |
| 81 |
} |
| 82 |
|
| 83 |
onMessage (event) { |
| 84 |
const data = JSON.parse(event.data) |
| 85 |
|
| 86 |
switch (data.type) { |
| 87 |
case GQL.CONNECTION_ACK: { |
| 88 |
// This is the successful response to GQL.CONNECTION_INIT |
| 89 |
if (this.callback) { |
| 90 |
this.callback(null, this.subscribe.bind(this)) |
| 91 |
} |
| 92 |
break |
| 93 |
} |
| 94 |
case GQL.CONNECTION_ERROR: { |
| 95 |
// This may occur: |
| 96 |
// 1. In response to GQL.CONNECTION_INIT |
| 97 |
// 2. In case of parsing errors in the client which will not disconnect. |
| 98 |
if (this.callback) { |
| 99 |
this.callback(new Error(data.payload), this) |
| 100 |
} |
| 101 |
break |
| 102 |
} |
| 103 |
case GQL.CONNECTION_KEEP_ALIVE: { |
| 104 |
// This may occur: |
| 105 |
// 1. After GQL.CONNECTION_ACK, |
| 106 |
// 2. Periodically to keep the connection alive. |
| 107 |
break |
| 108 |
} |
| 109 |
case GQL.DATA: { |
| 110 |
// This message is sent after GQL.START to transfer the result of the GraphQL subscription. |
| 111 |
const callback = this.subscriptions.get(data.id) |
| 112 |
if (callback) { |
| 113 |
const error = data.payload.errors ? new Error(data.payload.errors) : null |
| 114 |
callback(error, data.payload.data) |
| 115 |
} |
| 116 |
break |
| 117 |
} |
| 118 |
case GQL.ERROR: { |
| 119 |
// This method is sent when a subscription fails. This is usually dues to validation errors |
| 120 |
// as resolver errors are returned in GQL.DATA messages. |
| 121 |
const callback = this.subscriptions.get(data.id) |
| 122 |
if (callback) { |
| 123 |
callback(new Error(data.payload), null) |
| 124 |
} |
| 125 |
break |
| 126 |
} |
| 127 |
case GQL.COMPLETE: { |
| 128 |
// This is sent when the operation is done and no more dta will be sent. |
| 129 |
const callback = this.subscriptions.get(data.id) |
| 130 |
if (callback) { |
| 131 |
this.subscriptions.delete(data.id) |
| 132 |
// Return a null error and payload to indicate the subscription is closed. |
| 133 |
callback(null, null) |
| 134 |
} |
| 135 |
break |
| 136 |
} |
| 137 |
} |
| 138 |
} |
| 139 |
} |
| 140 |
|
| 141 |
function graphQLSubscriber (url, options, callback, protocols = 'graphql-ws') { |
| 142 |
const subscriber = new Subscriber(url, options, callback, protocols) |
| 143 |
return subscriber.shutdown.bind(subscriber) |
| 144 |
} |
