How to post from MetaTrader Terminal 5 MQL 5 a request to my nodejs server, which is running locally on my MT5 host?

半城伤御伤魂 提交于 2020-03-18 09:01:41

问题


I'm trying to get FX rates in my nodejs server and socke.io emit them to the client, while running MetaTrader Terminal 5 or 4.

So I guess I have to use MQL4/5. I know how the handle the request in my nodejs server. What I dont know is where to write the MQL4 code, what to config in my MetaTrader Terminal.

Lets say I want to send EUR/USD bid rate to my nodejs server everytime it gets changed. How do I achieve that, using MT4/5 and MQL4/5?

My nodejs code:

app.post('/fxroute', (req, res) => {
   console.log(req);
   let fxRates = req.body // dont know if the payload will be in body
   socket.emit('fxRates', fxRates);
});

MQL5 script:

#property copyright "Copyright 2017, MetaQuotes Software Corp."
#property link      "https://www.mql5.com"
#property version   "1.00"
//+------------------------------------------------------------------+
//| Script program start function                                    |
//+------------------------------------------------------------------+
void OnStart(){
     string  headers;
     char    data[],
             result[];
     string             str = "data=value";        // POST-data, variables to send    
     StringToCharArray( str,                data );
     string          b = CharArrayToString( data );
     Print( "Test:", b ); // just a test of data, if good ... OK, data was setup correctly.

     WebRequest( "POST",
                 "http://localhost:3000/fxroute",
                 NULL,
                 NULL,
                 3000,
                 data,
                 ArraySize( data ),
                 result,
                 headers
                 );
     Print( CharArrayToString( result ) );   // see the results
                                             // it returns
                                             // "Results:" No posted data.
  }

When I compile and run, I see that it was executed in MT Experts tab, but on my nodejs server, console logs nothing.


回答1:


Plan of work:

  1. Enable MT4/5 to use {http:|https:} transport-class to selected targets

  2. Create MT4/5 code to execute some kind of {http:|https:} based service

  3. Implement end-to-end logic to be wrapped + hidden inside the dumb http-protocol exchanges


1) Terminal permissions:

Using Terminal->Tools->Options enable [x] "Allow a WebRequest URL" to use a localhost {http:|https:} URL of your choice, matching the nodejs-server setup, in the list

2) WebRequest() code inside event-loop

Given your intentions, create an MQL4 script, using either a built-in IDE F4 or using an external editor of your choice and save the produced .mq4 script file in ~an_MT4_Terminal_Home_Directory/MQL4/Scripts directory

The event-loop is principally your design job:

int start() {
    while !isStopped() {                            // ACK LOOP
           if ( RefreshRates() ) {                  // NEW QUOTE has arrived
                ...                                 // JOB PROCESS Bid
                int aHttpRetCODE = WebRequest(...); // SIG-> NodeJS Server
                ...                                 // JOB PROCESS Response ( if a bi-directional service )
           }
           else {
                Sleep(...);                         // NOP on NACK, Terminal has nothing to do
           }
    }
}

For further details, may like to check my other posts on WebRequest() use-cases and warnings about it's principal limitations.

3) end-to-end logic

Here comes the creme-ala-creme of your design.


Is there any other way?

Yes, there is. That would be the one of my choice - using ZeroMQ or nanomsg on both sides ( MT4/5 Terminal & NodeJS ), thus being able to fully enjoy the freedom of a full-scale distributed systems design ( check the principal aMiniRESPONDER()-prototype example structure for [SIG,MSG] jobs in fully distributed systems ) .



来源:https://stackoverflow.com/questions/42098884/how-to-post-from-metatrader-terminal-5-mql-5-a-request-to-my-nodejs-server-whic

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