Communicating with an api/custom server using a HTTP request inside of .mq5 indicator code
Hello I have a .mq5 indicator and I have a custom flask python server running on local host (0.0.0.0:80)
I'm trying to setup a system where the indicator (inside of OnInit()) would send a HTTP POST request to the server with some information and then the server would return a message back based on the information that was sent.
I've been going down some rabbit holes. I found webrequest but this is not supported within indicator code, only EA/scripts from my understanding.
I found XML-rpc and using winlet.dll but both of these code articles are 10-11 years old. I made attempts at using both of them (connecting to a localhost python server on port 80) but was unable to be successful after spending several hours with both libraries. I had hard time debugging them since I wasn't sure if the code was just out of date or if I was missing something in the code. For the XML-RPC I couldn't even get a simple connection to my python server using the following code
What I'm now considering is writing my own .dll to send the POST request. I'm just sending a few string arguments in the POST request, it's nothing super complex like downloading files. I was considering using something like curl or https://github.com/elnormous/HTTPRequest, compiling the DLL, and then importing into .mq5.
I'm more so making this post to hopefully gain some helpful insight or ideas from the community. Is there something really easy that I'm missing and there is an easier way to do what I trying to accomplish? Is what I'm trying to do even possible? I really appreciate anyone taking the time to read through this and give me insight/ideas. Thanks!
Did you try WinInet.dll ?
- www.mql5.com
Yeah the third link I have in my post https://www.mql5.com/en/articles/276 is using winlet. I tried doing this but was unable to get a request to send successfully. I couldn't get the request to go through and show up on the server side. Had a hard time debugging the library and figuring out what was wrong. I thought it could be an issue with hosting the server on localhost and was toying with the idea of hosting it online using something like NGROK. Indicator code:
void OnInit(){ // open session if (!INet.Open("0.0.0.0", 80, "", "", INTERNET_SERVICE_HTTP)){ Alert("Can't connect to server."); return; } string Head="Content-Type: application/x-www-form-urlencoded"; // header string Path="/index"; // path to the page string Data ="hello=test"; string resp=""; tagRequest req; // initialization of parameters req.Init("POST", Path, Head, Data, false, resp, false); bool test = INet.Request(req); // send the request to the server Print(test); Print(req.stOut);
Python flask server code:
import os
from flask import Flask, request, Response
app = Flask(__name__)
@app.route('/index', methods=['POST'])
def respond():
return Response(status=200)
app.run(host="0.0.0.0", port=80) So I was toying with the idea of just using winlet or using something like curl in a C++ .dll and then importing the .dll into .mq5 code
- www.mql5.com
You can use MT5 Services to run background tasks and communicate with it from indicators using global variables.
Dumb question but can you elaborate at a high level how you would do this?
I think I understand the concept of global variables but having hard time understanding how you would send http requests with these global variables
Dumb question but can you elaborate at a high level how you would do this?
I think I understand the concept of global variables but having hard time understanding how you would send http requests with these global variables
There is a reason why WebRequest is not supported on Indicators. It is because all the Indicators run together on the same thread and if you use networking calls (which block), you will lock-up all indicators and the chart itself too.
So, don't use networking functionality in your indicator. Instead, create a separate MQL5 program and run it as a MQL5 service (see below), which runs on a separate dedicated thread.
You can then have that service use WebRequest to gather the data, and then send custom chart events to the Indicator with EventChartCustom() to communicate with it.
Program Running
Each script, each service and each Expert Advisor runs in its own separate thread. All indicators calculated on one symbol, even if they are attached to different charts, work in the same thread. Thus, all indicators on one symbol share the resources of one thread.
All other actions associated with a symbol, like processing of ticks and history synchronization, are also consistently performed in the same thread with indicators. This means that if an infinite action is performed in an indicator, all other events associated with its symbol will never be performed.
When running an Expert Advisor, make sure that it has an actual trading environment and can access the history of the required symbol and period, and synchronize data between the terminal and the server. For all these procedures, the terminal provides a start delay of no more than 5 seconds, after which the Expert Advisor will be started with available data. Therefore, in case there is no connection to the server, this may lead to a delay in the start of an Expert Advisor.
The below table contains a brief summary of MQL5 programs:
| Program | Running | Note |
|---|---|---|
| Service | A separate thread, the number of threads for services is equal to the number of services | A looped service cannot break running of other programs |
| Script | A separate thread, the number of threads for scripts is equal to the number of scripts | A looped script cannot break running of other programs |
| Expert Advisor | A separate thread, the number of threads for Expert Advisors is equal to the number of Expert Advisors | A looped Expert Advisor cannot break running of other programs |
| Indicator | One thread for all indicators on a symbol. The number of threads is equal to the number of symbols with indicators | An infinite loop in one indicator will stop all other indicators on this symbol |
There is a reason why WebRequest is not supported on Indicators. It is because all the Indicators run together on the same thread and if you use networking calls (which block), you will lock-up all indicators and the chart itself too.
So, don't use networking functionality in your indicator. Instead, create a separate MQL5 program and run it as a MQL5 service (see below), which runs on a separate dedicated thread.
You can then have that service use WebRequest to gather the data, and then send custom chart events to the Indicator with EventChartCustom() to communicate with it.
There is a reason why WebRequest is not supported on Indicators. It is because all the Indicators run together on the same thread and if you use networking calls (which block), you will lock-up all indicators and the chart itself too.
So, don't use networking functionality in your indicator. Instead, create a separate MQL5 program and run it as a MQL5 service (see below), which runs on a separate dedicated thread.
You can then have that service use WebRequest to gather the data, and then send custom chart events to the Indicator with EventChartCustom() to communicate with it.
Many thank Fernando Carreiro,
Because of " Services are unloaded immediately after completing their work " , is there any way to trigger service from Indicator?
You are misinterpreting that phrase. A Service will usually not return immediately and instead have a loop to keep it running indefinitely until some condition signals it to end its execution.
You are misinterpreting that phrase. A Service will usually not return immediately and instead have a loop to keep it running indefinitely until some condition signals it to end its execution.
1. Sorry if i wrong but when i try thi simply code:
//+------------------------------------------------------------------+ //| Service program start function | //+------------------------------------------------------------------+ void OnStart() { //--- Print("service execute!"); } //+------------------------------------------------------------------+
when i run this service. console show that just run one and stop (icon from test2 service change to stop - red).
So i think service just run once when enable this.
In my case, indicator have to send message to service and service have to forward message to other api. I think about two way solve this case are:
1- indicator execute service directly to send message.
2- indicator write to file and every time file created or change, service "know" and do their job.
My question is: is how to execute service from indicator or ea?
Thanks for your time!
Yes, but did I not say "... instead have a loop to keep it running indefinitely until some condition signals it to end its execution "?
When you code a service, you have to use a "loop" to keep it running. In essence a service and a script behave basically the same, but to keep a service alive and running you have to use a loop.
// Script/Service main function. void OnStart() { while( !IsStopped() ) { // Do Something }; };
Unfortunately, I don't know of any example of a service in the CodeBase in order to provide you with an example.
As for "how to execute service from indicator or ea", you can't as far as I know, unless you use DLL calls to the Windows API.
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Hello I have a .mq5 indicator and I have a custom flask python server running on local host (0.0.0.0:80)
I'm trying to setup a system where the indicator (inside of OnInit()) would send a HTTP POST request to the server with some information and then the server would return a message back based on the information that was sent.
I've been going down some rabbit holes. I found webrequest but this is not supported within indicator code, only EA/scripts from my understanding.
I found XML-rpc and using winlet.dll but both of these code articles are 10-11 years old. I made attempts at using both of them (connecting to a localhost python server on port 80) but was unable to be successful after spending several hours with both libraries. I had hard time debugging them since I wasn't sure if the code was just out of date or if I was missing something in the code. For the XML-RPC I couldn't even get a simple connection to my python server using the following code
What I'm now considering is writing my own .dll to send the POST request. I'm just sending a few string arguments in the POST request, it's nothing super complex like downloading files. I was considering using something like curl or https://github.com/elnormous/HTTPRequest, compiling the DLL, and then importing into .mq5.
I'm more so making this post to hopefully gain some helpful insight or ideas from the community. Is there something really easy that I'm missing and there is an easier way to do what I trying to accomplish? Is what I'm trying to do even possible? I really appreciate anyone taking the time to read through this and give me insight/ideas. Thanks!