New Gateway_UpdateFromJson api, which enables to dynamically create Modules, Loaders and Links from JSON Content.

Author: aribeironovaes

core/devdoc/gateway_createfromjson_requirements.md

@@ -65,7 +65,7 @@ extern GATEWAY_HANDLE Gateway_CreateFromJson(const char* file_path);
 #endif
 ```
 
-##Gateway_CreateFromJson
+## Gateway_CreateFromJson
 ```
 extern GATEWAY_HANDLE Gateway_CreateFromJson(const char* file_path);
 ```
@@ -118,3 +118,30 @@ Gateway_CreateFromJson creates a new gateway using information contained within
 **SRS_GATEWAY_JSON_17_002: [** This function shall return `NULL` if starting the gateway fails. **]**
 
 **SRS_GATEWAY_JSON_14_008: [** This function shall return `NULL` upon any memory allocation failure. **]**
+
+
+## Gateway_UpdateFromJson
+```
+extern int Gateway_UpdateFromJson(GATEWAY_HANDLE gw, const char* json_content);
+```
+Gateway_UpdateFromJson adds loades, modules or links based on a well-formed JSON configuration content.
+
+**SRS_GATEWAY_JSON_04_003: [** If `json_content` is NULL the function shall return GATEWAY_UPDATE_FROM_JSON_ERROR. **]**
+
+**SRS_GATEWAY_JSON_04_004: [** If `gw` is NULL the function shall return GATEWAY_UPDATE_FROM_JSON_ERROR.
+ **]**
+
+**SRS_GATEWAY_JSON_04_005: [** The function shall use *parson* to parse the JSON string to a *parson* `JSON_Value` structure. **]**
+
+**SRS_GATEWAY_JSON_04_006: [** The function shall return NULL if the JSON content could not be parsed to a `JSON_Value`. **]**
+
+**SRS_GATEWAY_JSON_04_007: [** The function shall traverse the `JSON_Value` object to initialize a `GATEWAY_PROPERTIES` instance. **]**
+
+**SRS_GATEWAY_JSON_04_010: [** The function shall return NULL if the `JSON_Value` contains incomplete information. **]**
+
+**SRS_GATEWAY_JSON_04_011: [** The function shall be able to add just `modules`, just `links` or both.
+ **]**
+
+**SRS_GATEWAY_JSON_04_009: [** The function shall be able to roll back previous operation if any `module` or `link` fails to be added. **]**
+
+**SRS_GATEWAY_JSON_04_008: [** This function shall return GATEWAY_UPDATE_FROM_JSON_ERROR upon any memory allocation failure. **]**

core/inc/gateway.h

@@ -46,6 +46,17 @@ DEFINE_ENUM(GATEWAY_ADD_LINK_RESULT, GATEWAY_ADD_LINK_RESULT_VALUES);
  */
 DEFINE_ENUM(GATEWAY_START_RESULT, GATEWAY_START_RESULT_VALUES);
 
+#define GATEWAY_UPDATE_FROM_JSON_RESULT_VALUES \
+    GATEWAY_UPDATE_FROM_JSON_SUCCESS, \
+    GATEWAY_UPDATE_FROM_JSON_ERROR, \
+    GATEWAY_UPDATE_FROM_JSON_INVALID_ARG, \
+    GATEWAY_UPDATE_FROM_JSON_MEMORY
+
+/** @brief      Enumeration describing the result of ::Gateway_UpdateFromJson.
+*/
+DEFINE_ENUM(GATEWAY_UPDATE_FROM_JSON_RESULT, GATEWAY_UPDATE_FROM_JSON_RESULT_VALUES);
+
+
 /** @brief      Struct representing a single link for a gateway. */
 typedef struct GATEWAY_LINK_ENTRY_TAG
 {
@@ -153,6 +164,19 @@ typedef struct GATEWAY_PROPERTIES_DATA_TAG
  */
 GATEWAY_EXPORT GATEWAY_HANDLE Gateway_CreateFromJson(const char* file_path);
 
+
+
+/** @brief      Updates a gateway using a JSON configuration  string as input
+ *              which describes each module. 
+ *
+ *  @param      gw          Pointer to a #GATEWAY_HANDLE from which to remove
+ *                          the module.
+ *  @param      json_content A JSON string with a list of Loaders, Modules and/or Links.
+ *
+ *  @return     A GATEWAY_UPDATE_FROM_JSON_RESULT with the operation result.
+ */
+GATEWAY_EXPORT GATEWAY_UPDATE_FROM_JSON_RESULT Gateway_UpdateFromJson(GATEWAY_HANDLE gw, const char* json_content);
+
 /** @brief      Creates a new gateway using the provided #GATEWAY_PROPERTIES.
  *
  *  @param      properties      #GATEWAY_PROPERTIES structure containing