How to use LBank's WebSocket API?

Using LBank's WebSocket API can be an effective way to receive real-time data and execute trades more efficiently. This article will guide you through the process of setting up and using the WebSocket API provided by LBank, a popular cryptocurrency exchange. By following this detailed guide, you'll be able to integrate real-time market data and trading capabilities into your applications.

Understanding WebSocket API Basics

Before diving into the specifics of LBank's WebSocket API, it's important to understand what a WebSocket API is and how it differs from traditional HTTP requests. WebSocket APIs provide a full-duplex communication channel over a single TCP connection, allowing for real-time data transfer between the client and the server. This is particularly useful in the cryptocurrency trading space, where timely updates can be crucial.

LBank's WebSocket API allows users to subscribe to real-time market data, such as price updates, order book changes, and trade executions. To start using the API, you'll need to establish a WebSocket connection to LBank's server.

Setting Up the WebSocket Connection

To begin, you need to establish a connection to LBank's WebSocket server. Here's how you can do it:

• Choose a WebSocket Library: You'll need a WebSocket library for your programming language. Popular choices include websocket-client for Python, ws for Node.js, and WebSocket for Java.
• Connect to the Server: The WebSocket endpoint for LBank is wss://api.lbkex.com/ws. Use your chosen library to establish a connection to this endpoint.

Here's an example in Python using the websocket-client library:

import websocket





def on_open(ws):





print('Opened connection')
def on_message(ws, message):
 
print(message)
def on_error(ws, error):
 
print(error)
def on_close(ws, close_status_code, close_msg):
 
print('Closed connection')
if name == '__main__':
 
websocket.enableTrace(True)
ws = websocket.WebSocketApp('wss://api.lbkex.com/ws',
                          on_open=on_open,
                          on_message=on_message,
                          on_error=on_error,
                          on_close=on_close)

ws.run_forever()
Subscribing to Market Data
Once the connection is established, you can subscribe to various types of market data. LBank's WebSocket API supports several types of subscriptions, including:
 
Ticker Data: Real-time price updates for specific trading pairs.
Order Book Data: Real-time updates on the current state of the order book.
Trade Data: Real-time updates on executed trades.
To subscribe to these data streams, you need to send a JSON-formatted message to the WebSocket server. Here's how to subscribe to ticker data for the BTC/USDT pair:
 
{
'sub': 'market.btcusdt.ticker', 'id': '12345'}

Send this message through your WebSocket connection:

ws.send(json.dumps({





'sub': 'market.btcusdt.ticker',
'id': '12345'
}))

You will receive ticker data in real-time, which you can handle in the on_message function.

Handling Received Data

When you receive data from the WebSocket API, it will be in JSON format. Here's an example of how you might handle ticker data:

import json





def on_message(ws, message):





data = json.loads(message)
if 'ch' in data and data['ch'] == 'market.btcusdt.ticker':
    ticker = data['tick']
    print(f'Latest Price: {ticker['close']}')
    print(f'24h Volume: {ticker['vol']}')
This code parses the JSON message and extracts the latest price and 24-hour trading volume for the BTC/USDT pair.
 
Placing Orders via WebSocket
LBank's WebSocket API also allows you to place orders directly. To do this, you need to authenticate your connection and then send the appropriate JSON message. Here's how to do it:
 
Authenticate: Send an authentication message with your API key and signature.
Place an Order: Send an order message with the necessary parameters.
Here's an example of how to authenticate and place a buy order:
 
import hmac
import timeimport json
 
api_key = 'YOUR_API_KEY'api_secret = 'YOUR_API_SECRET'
 
def get_signature(timestamp, method, request_path, body):
 
payload = timestamp + method + request_path + (body or '')
return hmac.new(api_secret.encode('utf-8'), payload.encode('utf-8'), digestmod='sha256').hexdigest()
def authenticate(ws):
 
timestamp = str(int(time.time() * 1000))
signature = get_signature(timestamp, 'GET', '/users/self/verify', '')
auth_message = {
    'op': 'auth',
    'args': [api_key, timestamp, signature]
}
ws.send(json.dumps(auth_message))
def place_order(ws):
 
order_message = {
    'op': 'order',
    'args': [{
        'symbol': 'btcusdt',
        'type': 'buy',
        'price': '30000',
        'amount': '0.01'
    }]
}
ws.send(json.dumps(order_message))
if name == '__main__':
 
websocket.enableTrace(True)
ws = websocket.WebSocketApp('wss://api.lbkex.com/ws',
                          on_open=lambda ws: (authenticate(ws), place_order(ws)),
                          on_message=on_message,
                          on_error=on_error,
                          on_close=on_close)

ws.run_forever()
This code authenticates the connection and then places a buy order for 0.01 BTC at a price of 30,000 USDT.
 
Unsubscribing from Market Data
If you need to stop receiving updates for a particular data stream, you can unsubscribe by sending an unsubscribe message. Here's how to unsubscribe from the ticker data for the BTC/USDT pair:
 
{
'unsub': 'market.btcusdt.ticker', 'id': '12345'}

Send this message through your WebSocket connection:

ws.send(json.dumps({





'unsub': 'market.btcusdt.ticker',
'id': '12345'
}))

FAQs

Q: Can I use LBank's WebSocket API for multiple trading pairs simultaneously?

A: Yes, you can subscribe to multiple trading pairs by sending separate subscription messages for each pair. For example, to subscribe to both BTC/USDT and ETH/USDT ticker data, you would send:

{  'sub': 'market.btcusdt.ticker',  'id': '12345'}

and

{  'sub': 'market.ethusdt.ticker',  'id': '12346'}

Q: What should I do if the WebSocket connection drops?

A: If the WebSocket connection drops, your application should attempt to reconnect automatically. You can implement a reconnection mechanism in your code to handle this scenario. For example, in Python:

import time





def on_error(ws, error):





print(error)
time.sleep(5)  # Wait for 5 seconds before attempting to reconnect
ws.run_forever()
def on_close(ws, close_status_code, close_msg):
 
print('Closed connection')
time.sleep(5)  # Wait for 5 seconds before attempting to reconnect
ws.run_forever()
Q: How can I ensure the security of my API key when using the WebSocket API? 
A: To ensure the security of your API key, never hardcode it into your script. Instead, use environment variables or a secure configuration file to store your API key and secret. Additionally, always use HTTPS (wss://) for WebSocket connections to encrypt your data in transit.