Add Websocket#subscribe() and #unsubscribe()

README.md

@@ -474,7 +474,9 @@ websocket.on('close', () => {
 });
 ```
 
-Optionally set the heartbeat mode or websocket URI.
+The client will automatically subscribe to the `heartbeat` channel. By
+default, the `full` channel will be subscribed to unless other channels are
+requested.
 
 ```javascript
 const websocket = new Gdax.WebsocketClient(
@@ -485,8 +487,34 @@ const websocket = new Gdax.WebsocketClient(
     secret: 'suchsecret',
     passphrase: 'muchpassphrase',
   },
-  { heartbeat: true }
+  { channels: ['full', 'level2'] }
 );
+
+```
+
+Optionally, [change subscriptions at runtime](https://docs.gdax.com/#subscribe):
+
+```javascript
+websocket.unsubscribe({ channels: ['full'] });
+
+websocket.subscribe({ product_ids: ['LTC-USD'], channels: ['ticker', 'user'] });
+
+websocket.subscribe({
+  channels: [{
+    name: 'user',
+    product_ids: ['ETH-USD']
+  }]
+});
+
+websocket.unsubscribe({
+  channels: [{
+    name: 'user',
+    product_ids: ['LTC-USD']
+  }, {
+    name: 'user',
+    product_ids: ['ETH-USD']
+  }]
+});
 ```
 
 The following events can be emitted from the `WebsocketClient`:

lib/clients/websocket.js

@@ -48,26 +48,37 @@ class WebsocketClient extends EventEmitter {
     this.socket = null;
   }
 
-  onOpen() {
-    this.emit('open');
+  _sendSubscription(type, { product_ids, channels }) {
+    const message = { type };
 
-    const subscribeMessage = {
-      type: 'subscribe',
-      product_ids: this.productIDs,
-      channels: this.channels,
-    };
+    if (channels) {
+      message.channels = channels;
+    }
+
+    if (product_ids) {
+      message.product_ids = product_ids;
+    }
 
     // Add Signature
     if (this.auth.secret) {
-      let sig = signRequest(
-        this.auth,
-        'GET',
-        this.channels ? '/users/self/verify' : '/users/self'
-      );
-      Object.assign(subscribeMessage, sig);
+      const sig = signRequest(this.auth, 'GET', '/users/self/verify');
+      Object.assign(message, sig);
     }
 
-    this.socket.send(JSON.stringify(subscribeMessage));
+    this.socket.send(JSON.stringify(message));
+  }
+
+  subscribe({ product_ids, channels }) {
+    this._sendSubscription('subscribe', { product_ids, channels });
+  }
+
+  unsubscribe({ product_ids, channels }) {
+    this._sendSubscription('unsubscribe', { product_ids, channels });
+  }
+
+  onOpen() {
+    this.emit('open');
+    this.subscribe({ product_ids: this.productIDs, channels: this.channels });
   }
 
   onClose() {

lib/orderbook_sync.js

@@ -31,15 +31,17 @@ class OrderbookSync extends WebsocketClient {
       this._client = new PublicClient(this.apiURI);
     }
 
-    this.productIDs.forEach(productID => {
-      this._queues[productID] = [];
-      this._sequences[productID] = -2;
-      this.books[productID] = new Orderbook();
-    });
+    this.productIDs.forEach(this._newProduct, this);
 
     this.on('message', this.processMessage.bind(this));
   }
 
+  _newProduct(productID) {
+    this._queues[productID] = [];
+    this._sequences[productID] = -2;
+    this.books[productID] = new Orderbook();
+  }
+
   loadOrderbook(productID) {
     if (!this.books[productID]) {
       return;
@@ -67,8 +69,21 @@ class OrderbookSync extends WebsocketClient {
       .catch(problems);
   }
 
+  // subscriptions changed -- possible new products
+  _newSubscription(data) {
+    const channel = data.channels.find(c => c.name === 'full');
+    channel && channel.product_ids
+      .filter(productID => !(productID in this.books))
+      .forEach(this._newProduct, this);
+  }
+
   processMessage(data) {
-    const { product_id } = data;
+    const { type, product_id } = data;
+
+    if (type === 'subscriptions') {
+      this._newSubscription(data);
+      return;
+    }
 
     if (this._sequences[product_id] < 0) {
       // Orderbook snapshot not loaded yet
@@ -100,7 +115,7 @@ class OrderbookSync extends WebsocketClient {
     this._sequences[product_id] = data.sequence;
     const book = this.books[product_id];
 
-    switch (data.type) {
+    switch (type) {
       case 'open':
         book.add(data);
         break;

tests/websocket.spec.js

@@ -99,6 +99,117 @@ suite('WebsocketClient', () => {
     });
   });
 
+  test('subscribes to additional products', done => {
+    let client;
+    const server = testserver(port, () => {
+      client = new Gdax.WebsocketClient([], 'ws://localhost:' + port);
+    });
+    server.on('connection', socket => {
+      socket.once('message', data => {
+        const msg = JSON.parse(data);
+        assert.equal(msg.type, 'subscribe');
+
+        socket.on('message', data => {
+          const msg = JSON.parse(data);
+          assert.equal(msg.type, 'subscribe');
+          assert.ok(msg.product_ids.includes('ETH-BTC'));
+          assert.ok(msg.product_ids.includes('ETH-USD'));
+
+          server.close();
+          done();
+        });
+        client.subscribe({ product_ids: ['ETH-BTC', 'ETH-USD'] });
+      });
+    });
+  });
+
+  test('unsubscribes from product', done => {
+    let client;
+    const server = testserver(port, () => {
+      client = new Gdax.WebsocketClient(['BTC-USD'], 'ws://localhost:' + port);
+    });
+    server.on('connection', socket => {
+      socket.once('message', data => {
+        const msg = JSON.parse(data);
+        assert.equal(msg.type, 'subscribe');
+
+        socket.on('message', data => {
+          const msg = JSON.parse(data);
+          assert.equal(msg.type, 'unsubscribe');
+          assert.deepEqual(msg.product_ids, ['BTC-USD']);
+          assert.deepEqual(msg.channels, ['full']);
+
+          server.close();
+          done();
+        });
+        client.unsubscribe({ product_ids: ['BTC-USD'], channels: ['full'] });
+      });
+    });
+  });
+
+  test('subscribes to additional channels', done => {
+    let client;
+    const server = testserver(port, () => {
+      client = new Gdax.WebsocketClient(
+        ['BTC-USD'],
+        'ws://localhost:' + port,
+        null,
+        { channels: ['heartbeat'] }
+      );
+    });
+    server.on('connection', socket => {
+      socket.once('message', data => {
+        const msg = JSON.parse(data);
+        assert.equal(msg.type, 'subscribe');
+
+        socket.on('message', data => {
+          const msg = JSON.parse(data);
+          assert.equal(msg.type, 'subscribe');
+          assert.deepEqual(msg.channels, [
+            {
+              name: 'ticker',
+              product_ids: ['LTC-USD'],
+            },
+          ]);
+
+          server.close();
+          done();
+        });
+        client.subscribe({
+          channels: [{ name: 'ticker', product_ids: ['LTC-USD'] }],
+        });
+      });
+    });
+  });
+
+  test('unsubscribes from channel', done => {
+    let client;
+    const server = testserver(port, () => {
+      client = new Gdax.WebsocketClient(
+        ['BTC-USD'],
+        'ws://localhost:' + port,
+        null,
+        { channels: ['ticker'] }
+      );
+    });
+    server.on('connection', socket => {
+      socket.once('message', data => {
+        const msg = JSON.parse(data);
+        assert.equal(msg.type, 'subscribe');
+
+        socket.on('message', data => {
+          const msg = JSON.parse(data);
+          assert.equal(msg.type, 'unsubscribe');
+          assert.deepEqual(msg.channels, ['ticker']);
+
+          server.close();
+          done();
+        });
+        client.unsubscribe({ channels: ['ticker'] });
+      });
+    });
+  });
+
   test('passes authentication details through', done => {
     const server = testserver(port, () => {
       new Gdax.WebsocketClient('ETH-USD', 'ws://localhost:' + port, {