The Ultimate Guide to MQL4 Websockets: Everything You Need to Know

Introduction

MQL4 is a programming language used by MetaTrader 4, a popular trading platform for Forex and other financial markets. MQL4 allows traders to create custom indicators, automated trading systems, and other tools to help them make better trading decisions.

One of the most useful features of MQL4 is its support for WebSockets, a protocol for real-time communication between a client (such as a trading robot) and a server. In this article, we’ll explore what WebSockets are, how they work, and how to use them in MQL4.

What are WebSockets?

WebSockets are a protocol for real-time, bi-directional communication between a client and a server. Unlike traditional HTTP requests, which are one-way and require the client to constantly poll the server for updates, WebSockets allow the server to push data to the client as soon as it becomes available.

WebSockets are especially useful for applications that require real-time updates, such as chat rooms, online games, and financial trading platforms. They are also more efficient than traditional HTTP requests, since they eliminate the need for constant polling and reduce the amount of data that needs to be transferred.

How do WebSockets work?

WebSockets work by establishing a long-lived connection between a client and a server. When the connection is first established, a handshake process takes place to establish the parameters of the connection, such as the version of the WebSocket protocol being used and any extensions or subprotocols being used.

Once the handshake is complete, the client and server can send messages to each other using the WebSocket protocol. Messages are sent as binary or text data frames, which can be fragmented into multiple frames if necessary. The client and server can also send ping and pong messages to each other to ensure that the connection is still active.

How to use WebSockets in MQL4

To use WebSockets in MQL4, you’ll need to use a third-party library that provides WebSocket functionality. One popular library is “WebSocket for MQL4” by Timur Gatin, which is available for free on the MQL5 Market.

To use the WebSocket library, you’ll need to include the appropriate header files in your MQL4 code and create an instance of the WebSocket client class. You can then connect to a WebSocket server using the Connect() method and send messages using the Send() method.

Here’s a simple example of how to use the WebSocket library:

  1. Include the WebSocket header files in your MQL4 code:
  2. #include <websocket.mqh>#include <websocket_events.mqh>

  3. Create an instance of the WebSocket client class:
  4. CWebSocketClient ws;

  5. Connect to a WebSocket server:
  6. ws.Connect(“wss://example.com/path/to/websocket”);

  7. Send a message:
  8. ws.Send(“Hello, world!”);

Of course, this is just a simple example. In practice, you’ll need to handle events such as connection errors, message reception, and WebSocket closure. The WebSocket library provides a set of event handlers that you can override in your code to handle these events.

Advantages of using WebSockets in MQL4

There are several advantages to using WebSockets in MQL4:

  • Real-time updates: With WebSockets, you can receive real-time updates from a trading server, allowing you to make faster and more accurate trading decisions.
  • Reduced network traffic: Since WebSockets eliminate the need for constant polling, they can reduce the amount of network traffic required by your trading robot.
  • Improved performance: WebSockets can provide faster and more efficient communication between your trading robot and the trading server, improving overall performance.

Limitations of using WebSockets in MQL4

There are also some limitations to using WebSockets in MQL4:

  • Compatibility: Not all trading servers support WebSockets, so you may need to check with your broker or trading platform provider to see if they offer WebSocket support.
  • Complexity: Working with WebSockets can be more complex than using traditional HTTP requests, so you may need to invest some time and effort in learning how to use them effectively.
  • Security: Since WebSockets allow real-time communication between a client and a server, they can potentially be used for malicious purposes. You’ll need to take appropriate security measures to ensure that your trading robot is protected from attacks.

FAQ

What is MQL4?

MQL4 is a programming language used by MetaTrader 4, a popular trading platform for Forex and other financial markets. MQL4 allows traders to create custom indicators, automated trading systems, and other tools to help them make better trading decisions.

What are WebSockets?

WebSockets are a protocol for real-time, bi-directional communication between a client and a server. They are especially useful for applications that require real-time updates, such as chat rooms, online games, and financial trading platforms.

How do WebSockets work?

WebSockets work by establishing a long-lived connection between a client and a server. Messages are sent as binary or text data frames, which can be fragmented into multiple frames if necessary. The client and server can also send ping and pong messages to each other to ensure that the connection is still active.

What are the advantages of using WebSockets in MQL4?

The advantages of using WebSockets in MQL4 include real-time updates, reduced network traffic, and improved performance.

What are the limitations of using WebSockets in MQL4?

The limitations of using WebSockets in MQL4 include compatibility issues, complexity, and security concerns.

What is the WebSocket for MQL4 library?

The WebSocket for MQL4 library is a third-party library that provides WebSocket functionality for MQL4. It allows traders to establish WebSocket connections with trading servers and receive real-time updates.