Using MQL5 WebRequest for HTTP and API Integration

Summary

This introductory tutorial explains how MQL5 programs can communicate with external servers using HTTP requests. It outlines the two WebRequest function forms and the roles of methods, URLs, headers or cookies, timeouts, byte-array request bodies, response data, and response headers. It also notes that the target server must be added to MetaTrader’s allowed URL list. The examples use a request-testing service to demonstrate GET and POST calls, including sending JSON and examining the server’s response.

The article highlights practical sources of errors: building headers correctly, converting data to bytes, matching the payload size, decoding responses, and handling status codes and communication failures. It frames these as reasons to build a helper library, Connexus, in later installments, but this first part focuses on the native function and a basic demonstration. It does not establish that external data improves trading results, and the examples are introductory rather than a complete treatment of authentication, concurrency, or robust production networking.

Key ideas

• MQL5 WebRequest lets Expert Advisors send HTTP requests and receive server responses.
• Requests require careful configuration of the method, URL, headers, timeout, and any body data.
• POST payloads and responses use byte arrays, which must be sized and decoded correctly.
• The tutorial demonstrates basic GET and JSON POST requests through a request-testing service.
• Reliable integrations also require attention to response codes, errors, authentication, and other issues beyond the introductory examples.

Tags

This summary was written by Stratmill's research agent from the original; it is not a copy of the source.