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docs/documentation/web/Extending_the_HTTP-API.md

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+##Extending the HTTP-API
+
+The HTTP-API is implemented as a collection of ```httpMethodHandlers```. An ```httpMethodHandler``` is a pointer to a function that is expected to respond to an HTTP GET request, using the **Cesanta Mongoose** framework. An ```httpMethodHandler``` is defined (in ```trick/WebServer.hh```) as follows:
+
+
+
+
+
+```c
+typedef void (*httpMethodHandler)(struct mg_connection*, struct http_message*);
+```
+
+Documentation for the **Cesanta Mongoose Networking Library** can be found at:
+[https://cesanta.com/docs/overview/intro.html](https://cesanta.com/docs/overview/intro.html)
+
+## Example HTTP-API Extension
+
+Suppose you want your web server to send you a JSON message: 
+
+```json
+{ "greeting" : "Hello Trick Sim Developer!" }
+```
+
+when you invoke the URL: ```http://localhost:8888/api/http/hello```.
+
+### Creating an ```httpMethodHandler```.
+
+The following two files will be our implementation of an ```httpMethodHandler```. We'll put these in some models directory  ```httpMethods/```.
+
+**```handle_HTTP_GET_hello.h```**
+
+```c
+#ifndef HANDLE_HTTP_GET_HELLO
+#define HANDLE_HTTP_GET_HELLO
+
+#ifndef SWIG
+void handle_HTTP_GET_hello(struct mg_connection *nc, struct http_message *hm);
+#endif
+
+#endif
+```
+
+**```handle_HTTP_GET_hello.c```**
+
+```c
+#include "mongoose/mongoose.h"
+
+void handle_HTTP_GET_hello(struct mg_connection *nc, struct http_message *hm) {
+    mg_printf(nc, "%s", "HTTP/1.1 200 OK\r\nTransfer-Encoding: chunked\r\n\r\n");
+    const char* json_text =
+        "{ \"greeting\" : \"Hello Trick Sim Developer!\" }";
+    mg_printf_http_chunk(nc, "%s", json_text);
+    mg_send_http_chunk(nc, "", 0);
+}
+```
+
+### Installing our ```httpMethodHandler```.
+
+We'll do this from our **S_define** file:
+
+* Add  ```(httpMethods/handle_HTTP_GET_hello.c)``` to the ```LIBRARY DEPENDENCIES```.
+
+* Include our header file:
+
+   ```##include "httpMethods/handle_HTTP_GET_hello.h"```
+   
+* In ```create_connections()``` add :
+
+```c
+web.server.installHTTPGEThandler( "hello", &handle_HTTP_GET_hello );
+```
+### A Complete S_define
+
+```c++
+/***********************TRICK HEADER*************************
+PURPOSE:
+    (Cannon Numeric)
+LIBRARY DEPENDENCIES:
+    (
+     (cannon/gravity/src/cannon_init.c)
+     (cannon/gravity/src/cannon_numeric.c)
+     (httpMethods/handle_HTTP_GET_hello.c)
+    )
+*************************************************************/
+
+#include "sim_objects/default_trick_sys.sm"
+#include "sim_objects/WebServer.sm"
+##include "cannon/gravity/include/cannon_numeric.h"
+##include "httpMethods/handle_HTTP_GET_hello.h"
+
+class CannonSimObject : public Trick::SimObject {
+
+    public:
+        CANNON      cannon ;
+        int foo;
+        CannonSimObject() {
+            ("default_data") cannon_default_data( &cannon ) ;
+            ("initialization") cannon_init( &cannon ) ;
+            ("derivative") cannon_deriv( &cannon ) ;
+            ("integration") trick_ret = cannon_integ( &cannon ) ;
+            ("dynamic_event") cannon_impact( &cannon) ;
+        }
+} ;
+CannonSimObject dyn ;
+
+IntegLoop dyn_integloop (0.01) dyn;
+
+void create_connections() {
+    dyn_integloop.getIntegrator(Runge_Kutta_4, 5);
+    web.server.installHTTPGEThandler( "hello", &handle_HTTP_GET_hello );
+}
+
+```