Created question in FIWARE Q/A platform on 24-01-2019 at 14:01
Please, ANSWER this question AT https://stackoverflow.com/questions/54347716/temperature-sensor-lwm2m-objects-3303-created

Question:
Temperature Sensor: LWM2M objects 3303 created

Description:
Working with wakaama client implementation of the LWM2M and Fiware Orion (of course using IoTAgent). I already have raspberry Pi sensor collecting temperature and stores in SQLite DB.

The scenario I want implement is to have the IoTAgent observes the wakaama LWM2M client (I mean client send the data to the IoTAgent.

I already created the 3303 object in wakaama/example/client/object_temperature.c then build, and I can confirm the client connects to the IoTAgent as far IoT logs (see below).

time=2019-01-24T12:51:15.270Z | lvl=DEBUG | corr=3e578c67-f589-4348-afaf-225509e9c787 | trans=3e578c67-f589-4348-afaf-225509e9c787 | op=IoTAgentNGSI.MongoDBDeviceRegister | srv=n/a | subsrv=n/a | msg=Looking for device with id [raspiSensorTV]. | comp=IoTAgent
time=2019-01-24T12:51:15.299Z | lvl=DEBUG | corr=n/a | trans=n/a | op=LWM2MLib.Registration | msg=Registration request ended successfully
time=2019-01-24T12:51:15.349Z | lvl=DEBUG | corr=n/a | trans=n/a | op=LWM2MLib.InformationReporting | msg=Observing value from resource /3303/0/0 in device [1]

But unfortunately, no are measure is sent by the client. Is anything wrong with my object_temperature.c? Code reproduced:

#include "liblwm2m.h"
#include "lwm2mclient.h"

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <ctype.h>
#include <time.h>
#include <sqlite3.h>

//Resource Id's
#define RES_SENSOR_VALUE 5700
#define RES_SENSOR_UNITS 5701

typedef struct prv_instance

{ struct _prv_instance_ * next; uint16_t shortID; double temp; char unit[10]; }

prv_instance_t;

static uint8_t prv_temperature_read(uint16_t instanceId,
int * numDataP,
lwm2m_data_t ** dataArrayP,
lwm2m_object_t * objectP)
{
prv_instance_t * targetP;
int i;
sqlite3 *db;
sqlite3_stmt *res;
char temperature_val[30];

targetP = (prv_instance_t *)lwm2m_list_find(objectP->instanceList, instanceId);
if (NULL == targetP) return COAP_404_NOT_FOUND;

fprintf(stderr, "----------------- Entering in prv_temperature ----------------\n");
// connect to the backend
int rc = sqlite3_open("../../urbansense.sqlite3", &db);

if (rc != SQLITE_OK)

{ fprintf(stderr, "Cannot open database: %s\n", sqlite3_errmsg(db)); sqlite3_close(db); return 1; }

else

{ fprintf(stderr, "Connection successful.\n" ); }

rc = sqlite3_prepare_v2(db, "SELECT temperature_data FROM basic_environment ORDER BY ID DESC LIMIT 1", -1, &res, 0);
if (rc != SQLITE_OK)

{ fprintf(stderr, "Failed to fetch data: %s\n", sqlite3_errmsg(db)); sqlite3_close(db); return 1; }

rc = sqlite3_step(res);
if (rc == SQLITE_ROW)

{ sprintf(temperature_val, "%s", sqlite3_column_text(res, 0)); fprintf(stdout, "Temperature value ==== : %s\n", sqlite3_column_text(res, 0)); sqlite3_finalize(res); sqlite3_close(db); }

if(*numDataP == 0)

{ *dataArrayP = lwm2m_data_new(1); if (*dataArrayP == NULL) return COAP_500_INTERNAL_SERVER_ERROR; *numDataP = 1; (*dataArrayP)[0].id = RES_SENSOR_VALUE; (*dataArrayP)[1].id = RES_SENSOR_UNITS; }

for (i = 0; i < *numDataP; i++)
{
switch((*dataArrayP)[i].id)

{ case RES_SENSOR_VALUE: lwm2m_data_encode_float(targetP->temp, *dataArrayP +1); break; case RES_SENSOR_UNITS: lwm2m_data_encode_string(targetP->unit, *dataArrayP +1); break; default: return COAP_404_NOT_FOUND; }

}
return COAP_205_CONTENT;
}

lwm2m_object_t * get_object_temperature()
{
/*

• The get_object_temperature function create the object itself and return a pointer to the structure that represent it.
  */
  lwm2m_object_t * temperatureObj;

temperatureObj = (lwm2m_object_t *)lwm2m_malloc(sizeof(lwm2m_object_t));

if (NULL != temperatureObj)
{
memset(temperatureObj, 0, sizeof(lwm2m_object_t));

/*

• Assigns it's unique ID 3303
  */
  temperatureObj->objID = LWM2M_TEMPERATURE_OBJECT_ID;

/*

• and its unique instance
  *
  */
  temperatureObj->instanceList = (lwm2m_list_t *)lwm2m_malloc(sizeof(lwm2m_list_t));
  if (NULL != temperatureObj->instanceList) { memset(temperatureObj->instanceList, 0, sizeof(lwm2m_list_t)); }

  else

  { lwm2m_free(temperatureObj); return NULL; }

temperatureObj->readFunc = prv_temperature_read;
temperatureObj->userData = lwm2m_malloc(sizeof(prv_instance_t));

}

return temperatureObj;
}

void free_object_temperature(lwm2m_object_t * objectP)
{
if (NULL != objectP->userData)

{ lwm2m_free(objectP->userData); objectP->instanceList = NULL; }

if(NULL != objectP->instanceList)

{ lwm2m_free(objectP->instanceList); objectP->instanceList = NULL; }

lwm2m_free(objectP);
}