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import {assert} from '@0xproject/assert';
import {schemas} from '@0xproject/json-schemas';
import * as _ from 'lodash';
import * as WebSocket from 'websocket';
import {
OrderbookChannel,
OrderbookChannelHandler,
OrderbookChannelMessageTypes,
OrderbookChannelSubscriptionOpts,
WebsocketClientEventType,
WebsocketConnectionEventType,
} from './types';
import {orderbookChannelMessageParsers} from './utils/orderbook_channel_message_parsers';
/**
* This class includes all the functionality related to interacting with a websocket endpoint
* that implements the standard relayer API v0
*/
export class WebSocketOrderbookChannel implements OrderbookChannel {
private _apiEndpointUrl: string;
private _client: WebSocket.client;
private _connectionIfExists?: WebSocket.connection;
private _subscriptionCounter = 0;
/**
* Instantiates a new WebSocketOrderbookChannel instance
* @param url The relayer API base WS url you would like to interact with
* @return An instance of WebSocketOrderbookChannel
*/
constructor(url: string) {
assert.isUri('url', url);
this._apiEndpointUrl = url;
this._client = new WebSocket.client();
}
/**
* Subscribe to orderbook snapshots and updates from the websocket
* @param subscriptionOpts An OrderbookChannelSubscriptionOpts instance describing which
* token pair to subscribe to
* @param handler An OrderbookChannelHandler instance that responds to various
* channel updates
*/
public subscribe(subscriptionOpts: OrderbookChannelSubscriptionOpts, handler: OrderbookChannelHandler): void {
assert.doesConformToSchema(
'subscriptionOpts', subscriptionOpts, schemas.relayerApiOrderbookChannelSubscribePayload);
assert.isFunction('handler.onSnapshot', _.get(handler, 'onSnapshot'));
assert.isFunction('handler.onUpdate', _.get(handler, 'onUpdate'));
assert.isFunction('handler.onError', _.get(handler, 'onError'));
assert.isFunction('handler.onClose', _.get(handler, 'onClose'));
this._subscriptionCounter += 1;
const subscribeMessage = {
type: 'subscribe',
channel: 'orderbook',
requestId: this._subscriptionCounter,
payload: subscriptionOpts,
};
this._getConnection((error, connection) => {
if (!_.isUndefined(error)) {
handler.onError(this, subscriptionOpts, error);
} else if (!_.isUndefined(connection) && connection.connected) {
connection.on(WebsocketConnectionEventType.Error, wsError => {
handler.onError(this, subscriptionOpts, wsError);
});
connection.on(WebsocketConnectionEventType.Close, () => {
handler.onClose(this, subscriptionOpts);
});
connection.on(WebsocketConnectionEventType.Message, message => {
this._handleWebSocketMessage(subscribeMessage.requestId, subscriptionOpts, message, handler);
});
connection.sendUTF(JSON.stringify(subscribeMessage));
}
});
}
/**
* Close the websocket and stop receiving updates
*/
public close() {
if (!_.isUndefined(this._connectionIfExists)) {
this._connectionIfExists.close();
}
}
private _getConnection(callback: (error?: Error, connection?: WebSocket.connection) => void) {
if (!_.isUndefined(this._connectionIfExists) && this._connectionIfExists.connected) {
callback(undefined, this._connectionIfExists);
} else {
this._client.on(WebsocketClientEventType.Connect, connection => {
this._connectionIfExists = connection;
callback(undefined, this._connectionIfExists);
});
this._client.on(WebsocketClientEventType.ConnectFailed, error => {
callback(error, undefined);
});
this._client.connect(this._apiEndpointUrl);
}
}
private _handleWebSocketMessage(requestId: number, subscriptionOpts: OrderbookChannelSubscriptionOpts,
message: WebSocket.IMessage, handler: OrderbookChannelHandler): void {
if (!_.isUndefined(message.utf8Data)) {
try {
const utf8Data = message.utf8Data;
const parserResult = orderbookChannelMessageParsers.parser(utf8Data);
if (parserResult.requestId === requestId) {
switch (parserResult.type) {
case (OrderbookChannelMessageTypes.Snapshot): {
handler.onSnapshot(this, subscriptionOpts, parserResult.payload);
break;
}
case (OrderbookChannelMessageTypes.Update): {
handler.onUpdate(this, subscriptionOpts, parserResult.payload);
break;
}
default: {
handler.onError(
this, subscriptionOpts, new Error(`Message has missing a type parameter: ${utf8Data}`));
}
}
}
} catch (error) {
handler.onError(this, subscriptionOpts, error);
}
} else {
handler.onError(this, subscriptionOpts, new Error(`Message does not contain utf8Data`));
}
}
}
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