SURVEYS MANAGER
===============

Surveys manager is the component of the openair system used to send
data to the server.

# Data

There are two kinds of data sent: surveys and errors. For performance
purpose, data are serialized in blocks of 10 rows at time.

## Surveys
 Surveys are the result of the sensor-reader and sensor-logger
 operations, they are read from sqlite3 data base and sent to
 the server as JSON object with following fields:
 
   * sensor    - Code to identify the sensor that perform the survey,
                 see Sensors section for more informations.
   * value     - Value of the surveys as number.
   * timestamp - Timestamp of the surveys taken at the read time.

## Errors
 Errors are logged in the error table of the openair.db. Data about
 errors are taken and sent to the server to allows administrators to
 be informed.

 Erros are sent in JSON object with following fields:

   * message   - Message of the error as a string.
   * timestamp - Timestamp of the moment of the error.

# Sensors
 Sensors are coded with numbers for memory optimization purposes, use
 following schema:
   * 0: PM10 sensor
   * 1: PM2.5 sensor
   * 2: temperature sensor
   * 3: humidity sensor
   * 4: pression sensor

 IMPORTANT: This software component does not use that informations,
            this send the data from the data base without making any
            check. This is documented for informations purpose.