Use paho-mqtt3c.dll in MT4 - How to write the import block?

[mt4programmer]

Hello,

I would like to transfer some information to an MQTT server. Since this is not part of the standard functionality, I would like to use a library which is available as a DLL (links below). Unfortunately I don't have much experience with MQL4 or C and fail with the import block definition.

I understand that the definition with simple data types is relatively simple. A nice example from Win32User.mqh:

#import "user32.dll"
   int SendMessageA(int hWnd,int Msg,int wParam,int lParam);
#import

As an example in my case I would like to use the following function: https://eclipse.github.io/paho.mqtt.c/MQTTClient/html/_m_q_t_t_client_8h.html#a9a0518d9ca924d12c1329dbe3de5f2b6

int MQTTClient_create ( MQTTClient * handle,
  const char * serverURI,
  const char * clientId,
  int persistence_type,
  void * persistence_context 
)

Can someone give me a hint how such a definition could look like in the definition block? I guess it should go in this direction:

#import "paho-mqtt3c.dll"
  int MQTTClient_create(???, const char *, const char *, int, ???)
#import

Links to the MQTT library:

• Library: https://github.com/eclipse/paho.mqtt.c
• Direct download of the DLLs: https://github.com/eclipse/paho.mqtt.c/releases/download/v1.3.12/eclipse-paho-mqtt-c-win32-1.3.12.zip
• API Docs: https://eclipse.github.io/paho.mqtt.c/MQTTClient/html/index.html

[Alain Verleyen]

Something like this ?

#import "paho-mqtt3c.dll"
  int MQTTClient_create(int , const char &[], const char &[], int, int)
#import

MT4 topic should be posted in MT4 section of the forum.