Please see examples/HttpCallExample/HttpCallExample.ino.

1. include and construct

   #include <httpcall.hpp>
   #include <WiFi.h>
   #include <ArduinoJson.h>
   
   // construct
   HttpCall httpcall;

2. begin

   void setup(void) {
       // ...
       WiFi.begin("your ssid", "your wifi password");
   
       httpcall.begin();
       // ...
   }

3. add function

   void setup(void) {
       // ...
       httpcall.begin();
       
       //           id      function   value is callback argument
       httpcall.add("test", "test", [](JsonObject j) {
           Serial.println("http called!");
       });
       // ...
   }

4. handle client

   void loop(void)
   {
       // ...
       httpcall.handleClient();
       // ...
   }

5. Call function POST method request to http://{your ip}/run.

   Request header is

   {
   "id": "test",
   "function": "test",
   "value": {
       // json
   }
   }

   curl command is

   curl -X POST "http://{your ip with port}/run" \
   -H "Content-Type: application/json" \
   -d '{
   "id": "test",
   "function": "test",
   "value": {
       "foo": bar"
   }
   }'