extern int j_read_object_at(struct json_object *obj, const char *key, struct json_object **value);
extern int j_read_string_at(struct json_object *obj, const char *key, const char **value);
extern int j_read_boolean_at(struct json_object *obj, const char *key, int *value);
extern int j_read_integer_at(struct json_object *obj, const char *key, int *value);
extern int j_read_object_at(struct json_object *obj, const char *key, struct json_object **value);
extern int j_read_string_at(struct json_object *obj, const char *key, const char **value);
extern int j_read_boolean_at(struct json_object *obj, const char *key, int *value);
extern int j_read_integer_at(struct json_object *obj, const char *key, int *value);