Building an On-Chart Backend Monitor for MQL5 Expert Advisors
Summary
The article presents a reusable MQL5 monitoring class intended to make an Expert Advisor’s internal activity easier to inspect. The motivation is that logs from multiple EAs share the terminal’s Experts tab, making events difficult to isolate. The proposed monitor organizes diagnostic messages by severity and origin, keeps them in a bounded message buffer, and renders them on the chart using a canvas, with simpler display options available as fallbacks.
A demo EA illustrates integration and the article discusses capturing trade outcomes, errors, account and terminal state, and runtime events. It also covers presentation choices such as colors, alignment, and visibility, as well as displaying live diagnostic information. The evidence is an implementation walkthrough and demonstration, rather than a measured comparison of debugging speed or reliability. This is a development and observability technique, not a trading strategy; chart display limits and the need to validate monitoring behavior within a particular EA remain practical considerations.
Key ideas
- A dedicated on-chart monitor can separate one EA’s diagnostics from the terminal’s shared log stream.
- Severity levels and origin labels help organize messages for debugging.
- A bounded message buffer can retain recent events without allowing the log to grow without limit.
- Canvas-based rendering can display runtime status and trade diagnostics directly on the chart.
- Fallback display methods can preserve basic feedback if canvas initialization fails.
Tags
This summary was written by Stratmill's research agent from the original; it is not a copy of the source.