diff --git a/Project/applications/smartcities/Makefile b/Project/applications/smartcities/Makefile
index 4b371da..3179a82 100644
--- a/Project/applications/smartcities/Makefile
+++ b/Project/applications/smartcities/Makefile
@@ -10,7 +10,7 @@
 SDK_ROOT = ../../
 PROJECT_OUT = smartcities
 
-USER_SRC = main.c httpClient.c
+USER_SRC = main.c httpClient.c callbacks.c
 USER_INCDIR = include/
 
 # if you need to add build Defines options add to USER_DEFS define 
diff --git a/Project/applications/smartcities/include/globals.h b/Project/applications/smartcities/include/globals.h
index b92ddd9..0691b8f 100644
--- a/Project/applications/smartcities/include/globals.h
+++ b/Project/applications/smartcities/include/globals.h
@@ -1,6 +1,7 @@
 #ifndef GLOBALS_H
 #define GLOBALS_H
 
-#define SERVER_IP		"10.0.60.241"
+#define SERVER_IP			"10.0.60.241"
+#define MODULE_ID_LENGTH	6
 
 #endif
\ No newline at end of file
diff --git a/Project/applications/smartcities/include/json.h b/Project/applications/smartcities/include/json.h
index c797e89..aeae30c 100644
--- a/Project/applications/smartcities/include/json.h
+++ b/Project/applications/smartcities/include/json.h
@@ -17,7 +17,7 @@
 char* prepare_json_statement(char** data, uint32_t nObservations);
 char* prepare_json_register_statement(char* module_ID, uint8_t sensor_type);
 char* prepare_observation(char* observation, uint32_t length);
-uint8_t send_observation(char* statement, uint32_t length, char* ID);
+uint8_t send_observation(char* statement, uint32_t length, char* provider_ID, char* sensor_ID);
 uint32_t find_next_index(char* string, uint32_t length, char delimiter);
 char* join_strings(char* str1, char* str2, uint32_t len1, uint32_t len2, bool)
 
diff --git a/Project/applications/smartcities/include/module.h b/Project/applications/smartcities/include/module.h
index e0a2659..84be2f8 100644
--- a/Project/applications/smartcities/include/module.h
+++ b/Project/applications/smartcities/include/module.h
@@ -1,6 +1,11 @@
 #ifndef MODULE_H
 #define MODULE_H
 
-#define SERIAL_NUMBER	"123456"
+typedef struct module_info {
+  char* ID;
+  char* geoloc;
+} module_info;
+
+module_info module = {"123456", "41.39479 2.148768"} /* append 0/1 flag for read write */ 
 
 #endif
\ No newline at end of file
diff --git a/Project/applications/smartcities/include/sensors.h b/Project/applications/smartcities/include/sensors.h
index 59746a7..6ad402d 100644
--- a/Project/applications/smartcities/include/sensors.h
+++ b/Project/applications/smartcities/include/sensors.h
@@ -1,5 +1,14 @@
 #ifndef SENSORS_H
 #define SENSORS_H
 
+typedef struct sensor_info {
+  uint8_t ID;
+  char* description;
+  char* type;
+  char* unit;
+} sensor_info;
 
-#endif
+sensor_info humidity_sensor = {ID = 0x77, "Humidity sensor", "humidity", "%"} /* append 0/1 flag for read write */ 
+
+
+#endif
\ No newline at end of file
diff --git a/Project/applications/smartcities/json.c b/Project/applications/smartcities/json.c
index 6f091fd..f5d4ab2 100644
--- a/Project/applications/smartcities/json.c
+++ b/Project/applications/smartcities/json.c
@@ -14,48 +14,48 @@ char* prepare_json_observation_statement(char** data, uint32_t nObservations)
 		length += observation_length;
 	}
 	length--; //REMOVE LAST ','
-	json_statement = join_strings(str_aux,"]}",length,2,JOIN_NO_FREE);
+	json_statement = join_strings(str_aux,"]}\0",length,3,JOIN_NO_FREE);
 	chHeapFree(str_aux);
 	return json_statement;
 }
 
-char* prepare_json_register_statement(char* module_ID, uint8_t sensor_type)
+char* prepare_json_register_statement(module_info module, sensor_info sensor)
 {
-	//id, desc, type, unit
-
 	unsigned int i, length, observation_length;
 	char *json_statement, *str_aux, *str_aux2;
-	length = 17;
-	str_aux = join_strings("{\"observations\":[","",length,0,JOIN_NO_FREE);
-	for(i = 0; i < nObservations; i++)
-	{
-		str_aux2 = prepare_observation(data[i],strlen(data[i]));
-		observation_length = strlen(str_aux2);
-		str_aux = join_strings(str_aux,str_aux2,length,observation_length,JOIN_FREE_MEM);
-		length += observation_length;
-	}
-	length--;
-	json_statement = join_strings(str_aux,"]}",length,2,JOIN_NO_FREE);
+	length = 23;
+	char* ID[MODULE_ID_LENGTH+3];
+	strcpy(ID,module.ID);
+	sprintf(ID+MODULE_ID_LENGTH,"%d",sensor.ID);
+	str_aux = join_strings("{\"sensors\":[{\"sensor\":\"",ID,length,MODULE_ID_LENGTH+2,JOIN_NO_FREE);
+	length += MODULE_ID_LENGTH+2;
+	str_aux2 = join_strings(str_aux,"\",\"description\":\"",length,17,JOIN_NO_FREE);
 	chHeapFree(str_aux);
-	return json_statement;
-
-	char *json_data, *str_aux, *str_aux2;
-	int value_length = find_next_index(observation,length,',');
-	int timestamp_length = length - (value_length + 1);
-	char *value = (char*) chHeapAlloc(NULL,value_length+1);
-	char *timestamp = (char*) chHeapAlloc(NULL,timestamp_length+1);
-	strncpy(value,observation,value_length);
-	strncpy(timestamp,observation+(value_length+1),timestamp_length);
-	value[value_length] = '\0';
-	timestamp[timestamp_length] = '\0';
-	str_aux = join_strings("{\"value\":\"",value,10,value_length,JOIN_NO_FREE);
-	str_aux2 = join_strings(str_aux,"\",\"timestamp\":\"",10+value_length,15,JOIN_NO_FREE);
-	str_aux2 = join_strings(str_aux2,timestamp,25+value_length,timestamp_length,JOIN_FREE_MEM);
-	json_data = join_strings(str_aux2,"\"},",25+value_length+timestamp_length,3,JOIN_NO_FREE);
+	length += 17;
+	str_aux = join_strings(str_aux2,sensor.description,length,strlen(sensor.description),JOIN_NO_FREE);
+	chHeapFree(str_aux2);
+	length += strlen(sensor.description);
+	str_aux2 = join_strings(str_aux,"\",\"type\":\"",length,10,JOIN_NO_FREE);
 	chHeapFree(str_aux);
+	length += 10;
+	str_aux = join_strings(str_aux2,sensor.type,length,strlen(sensors.type),JOIN_NO_FREE);
 	chHeapFree(str_aux2);
-	chHeapFree(value);
-	return json_data;
+	length += strlen(sensors.type);
+	str_aux2 = join_strings(str_aux,"\",\"unit\":\"",length,10,JOIN_NO_FREE);
+	chHeapFree(str_aux);
+	length += 10;
+	str_aux = join_strings(str_aux2,sensor.unit,length,strlen(sensor.unit),JOIN_NO_FREE);
+	chHeapFree(str_aux2);
+	length += strlen(sensor.unit);
+	str_aux2 = join_strings(str_aux,"\",\"location\":\"",length,14,JOIN_NO_FREE);
+	chHeapFree(str_aux);
+	length += 14;
+	str_aux = join_strings(str_aux2,module.geoloc,length,strlen(module.geoloc),JOIN_NO_FREE);
+	chHeapFree(str_aux2);
+	length += strlen(module.geoloc);
+	json_statement = join_strings(str_aux,"\"}]}\0",length,5,JOIN_NO_FREE);
+	chHeapFree(str_aux);
+	return json_statement;
 }
 
 char* prepare_observation(char* observation, uint32_t length)
@@ -161,4 +161,7 @@ char* join_strings(char* str1, char* str2, uint32_t len1, uint32_t len2, uint8_t
 		free(str2);
 	}
 	return str; 
-}
\ No newline at end of file
+}
+
+//check if exists
+//subscribe
\ No newline at end of file