1 files changed, 101 insertions, 0 deletions
diff --git a/packages/connect/src/ws_orders_channel.ts b/packages/connect/src/ws_orders_channel.ts
new file mode 100644
index 000000000..cde4acbc3
--- /dev/null
+++ b/packages/connect/src/ws_orders_channel.ts
@@ -0,0 +1,101 @@
+import * as _ from 'lodash';
+import { v4 as uuid } from 'uuid';
+import * as WebSocket from 'websocket';
+
+import { OrdersChannel, OrdersChannelHandler, OrdersChannelMessageTypes, OrdersChannelSubscriptionOpts } from './types';
+import { assert } from './utils/assert';
+import { ordersChannelMessageParser } from './utils/orders_channel_message_parser';
+
+export interface OrdersChannelSubscriptionOptsMap {
+    [key: string]: OrdersChannelSubscriptionOpts;
+}
+
+/**
+ * This class includes all the functionality related to interacting with a websocket endpoint
+ * that implements the standard relayer API v0
+ */
+export class WebSocketOrdersChannel implements OrdersChannel {
+    private readonly _client: WebSocket.w3cwebsocket;
+    private readonly _handler: OrdersChannelHandler;
+    private readonly _subscriptionOptsMap: OrdersChannelSubscriptionOptsMap = {};
+    /**
+     * Instantiates a new WebSocketOrdersChannel instance
+     * @param   client               A WebSocket client
+     * @param   handler              An OrdersChannelHandler instance that responds to various
+     *                               channel updates
+     * @return  An instance of WebSocketOrdersChannel
+     */
+    constructor(client: WebSocket.w3cwebsocket, handler: OrdersChannelHandler) {
+        assert.isOrdersChannelHandler('handler', handler);
+        // set private members
+        this._client = client;
+        this._handler = handler;
+        // attach client callbacks
+        this._client.onerror = err => {
+            this._handler.onError(this, err);
+        };
+        this._client.onclose = () => {
+            this._handler.onClose(this);
+        };
+        this._client.onmessage = message => {
+            this._handleWebSocketMessage(message);
+        };
+    }
+    /**
+     * Subscribe to orderbook snapshots and updates from the websocket
+     * @param   subscriptionOpts     An OrdersChannelSubscriptionOpts instance describing which
+     *                               assetData pair to subscribe to
+     */
+    public subscribe(subscriptionOpts: OrdersChannelSubscriptionOpts): void {
+        assert.isOrdersChannelSubscriptionOpts('subscriptionOpts', subscriptionOpts);
+        assert.assert(this._client.readyState === WebSocket.w3cwebsocket.OPEN, 'WebSocket connection is closed');
+        const requestId = uuid();
+        this._subscriptionOptsMap[requestId] = subscriptionOpts;
+        const subscribeMessage = {
+            type: 'subscribe',
+            channel: 'orders',
+            requestId,
+            payload: subscriptionOpts,
+        };
+        this._client.send(JSON.stringify(subscribeMessage));
+    }
+    /**
+     * Close the websocket and stop receiving updates
+     */
+    public close(): void {
+        this._client.close();
+    }
+    private _handleWebSocketMessage(message: any): void {
+        if (_.isUndefined(message.data)) {
+            this._handler.onError(this, new Error(`Message does not contain data. Url: ${this._client.url}`));
+            return;
+        }
+        try {
+            const data = message.data;
+            const parserResult = ordersChannelMessageParser.parse(data);
+            const subscriptionOpts = this._subscriptionOptsMap[parserResult.requestId];
+            if (_.isUndefined(subscriptionOpts)) {
+                this._handler.onError(
+                    this,
+                    new Error(`Message has unknown requestId. Url: ${this._client.url} Message: ${data}`),
+                );
+                return;
+            }
+            switch (parserResult.type) {
+                case OrdersChannelMessageTypes.Update: {
+                    this._handler.onUpdate(this, subscriptionOpts, parserResult.payload);
+                    break;
+                }
+                default: {
+                    this._handler.onError(
+                        this,
+                        new Error(`Message has unknown type parameter. Url: ${this._client.url} Message: ${data}`),
+                        subscriptionOpts,
+                    );
+                }
+            }
+        } catch (error) {
+            this._handler.onError(this, error);
+        }
+    }
+}