Adding functions to retrieve data from obelisk

- adding a new error class ObeliskDateTimeTypeError(Exception)
- adding a new function to retrieve the last value from a thing/sensor: def retrieve_last_value_from_obelisk
- adding a new function to retrieve values for a certain period from a thing/sensor: def retrieve_series_from_obelisk

obelisk/obeliskclient.py

@@ -13,6 +13,8 @@
 class ObeliskError(Exception):
     pass
 
+class ObeliskDateTimeTypeError(Exception):
+    pass
 
 class ObeliskPrecisions(Enum):
     MILLISECONDS = 1
@@ -130,3 +132,78 @@ def send_to_obelisk(self, data, refresh_rpt=False):
         except requests.exceptions.HTTPError as e:
             logger.error(e)
             raise ObeliskError("Could not send data to Obelisk.")
+
+    @retry_timeout
+    def retrieve_last_value_from_obelisk(self, metrics_id, thing_id, refresh_rpt=False):
+        try:
+            # Check the need to refresh the rpt token    
+            if refresh_rpt:
+                if not self._rpt_refresh_token_expire_date or self._rpt_refresh_token_expire_date < datetime.utcnow():
+                    self.__request_rpt_token()
+                else:
+                    self.__refresh_rpt_token()
+
+            # Specify necessary request information        
+            headers = {'Content-Type': 'application/json',
+                       'Authorization': 'Bearer {}'.format(self._rpt_token)}
+            url = "{}/api/{}/scopes/{}/metrics/{}/events/latest?filter=sourceId%3D{}".format(self._base_url, self._version, self._scope_id, metrics_id,thing_id)
+
+            # The request
+            resp = requests.get(url, headers=headers, timeout=10)
+            # In case of issues with the token refresh and retry          
+            if resp.status_code == 403 or resp.status_code == 401:
+                logger.debug("Requesting/renewing RPT token")
+                respjson=self.retrieve_last_value_from_obelisk(metrics_id, thing_id, refresh_rpt=True)
+            else:
+                resp.raise_for_status()
+                respjson=resp.json()
+
+            # Return the result
+            return respjson
+
+        except requests.exceptions.HTTPError as e:
+            logger.error(e)
+            raise ObeliskError("Could not retrieve last value for thing {} from Obelisk.".format(thing_id))
+
+    @retry_timeout
+    def retrieve_series_from_obelisk(self, metrics_id, thing_id, from_datetime, to_datetime=datetime.now(), refresh_rpt=False):
+        try:
+            # first check if the dates are provide in the proper datetime format
+            if not isinstance(from_datetime,datetime):
+                raise ObeliskDateTimeTypeError("From date is not of the correct type. Should be datetime.datetime")
+            else:
+                FromDateTimestamp=round(from_datetime.timestamp()*1000)
+            if not isinstance(to_datetime,datetime):
+                raise ObeliskDateTimeTypeError("To date is not of the correct type. Should be datetime.datetime")
+            else:
+                ToDateTimestamp=round(to_datetime.timestamp()*1000)
+
+            # Check the need to refresh the rpt token    
+            if refresh_rpt:
+                if not self._rpt_refresh_token_expire_date or self._rpt_refresh_token_expire_date < datetime.utcnow():
+                    self.__request_rpt_token()
+                else:
+                    self.__refresh_rpt_token()
+
+            # Specify necessary request information        
+            headers = {'Content-Type': 'application/json',
+                       'Authorization': 'Bearer {}'.format(self._rpt_token)}
+
+            url = "{}/api/{}/scopes/{}/metrics/{}/events?filter=sourceId%3D{}&from={}&to={}".format(self._base_url, self._version, self._scope_id,metrics_id,thing_id,FromDateTimestamp,ToDateTimestamp)
+
+            # The request
+            resp = requests.get(url, headers=headers, timeout=10)
+            # In case of issues with the token refresh and retry
+            if resp.status_code == 403 or resp.status_code == 401:
+                logger.debug("Requesting/renewing RPT token")
+                respjson=self.retrieve_series_from_obelisk(metrics_id, thing_id, from_datetime, to_datetime, refresh_rpt=True)
+            else:
+                resp.raise_for_status()
+                respjson=resp.json()
+
+            # Return the result
+            return respjson
+
+        except requests.exceptions.HTTPError as e:
+            logger.error(e)
+            raise ObeliskError("Could not retrieve values for thing {} for the specified period from Obelisk.".format(thing_id))