istSOS-WNS: Notification Service

the istSOS-WNS is a service gathering data from an istSOS database and sending a notification to the users after testing the retrieved data to meet some conditions. The systems is divided in three parts: a database for storing the information about the notifications, the users and the registrations of the users to the notifications; a database of the istSOS service storing the actual data received from external sensors; and a scheduler that periodically runs the functions to retrieve the data, test it and send the notifications to the registered users. The system also do a notification on a twitter account.

The following features are supported:
  • creation/deletion of notifications
  • creation/deletion of users
  • subscription/unsubscription of user to notification
  • request old notification

istSOS-WNS database schema

The wns schema is represented below.


Activation of istSOS-WNS

By default the istWNS use the database connection of the default service but you could specify a different db setting connection parameters editing the default.cfg file.

dbname = istsos
host =
user = postgres
password = postgres
port = 5432

The other parameter reported below are used to send notification via email or twitter

usermail =
password = ""
smtp = ""
port = ""

oauth_token = ""
oauth_secret = ""
consumer_key = ""
consumer_secret = ""


Actually the system update the status on twitter and can send notification via email.

To setup the Web Service do this GET request:


This will create a notification.asp file under the wns/ folder, where the notification function are stored and create a schema in the istSOS-WNS database.

Create a notification

It’s possible to create two type of notification,

  • Simple notification, that execute a getObservation and compare the results with a condition
  • Complex observation, the user write a specific requests and validation function in python

Method 1: simple notification

Do a POST request to:


with the following parameter

  1. name: the function name [mandatory]
  2. description: the description indicates what the function does [mandatory]
  3. period: expressed in ISO period format, is the interval over witch the getObservation will be performed, starting from now i.e. the last 2 hours. [optional]
  4. interval: expressed in minutes [mandatory]
  5. service: the service name [mandatory]
  6. condition: the condition describes in which case the notification will be performed. Every element retrived with the getObservation is tested again this contion, and as soon one element satisfies it the notification is triggered [mandatory]
  7. params: this is used to build a getObservation request. The offering, observedPropertiy and procedure are mandatory [mandatory]
  8. store: if true, store the result into the DB [optional]


    "name": "arduino_heat",
    "description": "check arduino DHT11 heat­index",
    "interval": 20,
    "params": {
    "condition": "> 26",
    "service": "demo",
    "period": "PT1H",
    "store": true

Method 2: complex notification

create a python function with the following constraint:

  1. The content of the function must have the structure of the extract below, retrieving the data, handling it and checking a condition to send out notifications.

  2. Pay attention to the function name you choose, because the exact name has to be used in the next step. The name also has to be unique, to avoid potential overriding.

  3. Every function must implement the notify() method, be sure to import the correct file (wns.notificationScheduler). The two lines specified in the extract should be copied in your method, to make sure you import the correct file.

  4. The ns.notify() method takes three arguments:
    1. functionName of the method you defined [mandatory]
    2. a python dict containing the message to send via twitter or mail [mandatory]
    3. Status: the last parameter is a flag, if True, the Notifier update the status of the twitter account [Optional, default True].
  5. A notify dict with the twitter and mail message to send. The two message cold be differnt because whit twitter you ave the constraint of 140 character.


def meanTemp():
    import datetime
    import time
    from lib.pytz import timezone
    now =[0]))
    endDate = now.strftime('%Y-%m-%dT%H:%M:%S%z')
    eventTime = now - datetime.timedelta(hours=5)
    startDate = eventTime.strftime('%Y-%m-%dT%H:%M:%S%z')

    startDate = datetime.datetime(2015,7,12,15,00,0, tzinfo=timezone(time.tzname[0])).strftime('%Y-%m-%dT%H:%M:%S%z')
    endDate = datetime.datetime(2015,7,12,16,00,0, tzinfo=timezone(time.tzname[0])).strftime('%Y-%m-%dT%H:%M:%S%z')

    rparams = {"service": "SOS", "offering": "temporary", "request": "GetObservation",
                "version": "1.0.0", "responseFormat": "application/json",
                "observedProperty": "air:temperature", "procedure": "T_BELLINZONA"}
    rparams['eventTime'] = str(startDate) + "/" +str(endDate)

    import lib.requests as requests
    res = requests.get('http://localhost/istsos/demo', params=rparams)

    result = res.json()['ObservationCollection']['member'][0]['result']['DataArray']['values']

    mean = 0
    count = 0

    for el in result:
        if float(el[1]) != -999.9:
            mean += float(el[1])
            count += 1

    if len(result) == 0:
        message = "Cannot make mean with no data"
        mean = mean / count
        message = "The mean temp in Bellinzona in the last hour: "  + str(mean)

    # this structure is mandatory to send notification
    notify = {
        "twitter": {
            "public": message,
            "private": message
            "subject": "mean temp from T_BELLINZONA",
            "message": message

    # these line are mandatory
    import wnslib.notificationScheduler as nS
    nS.notify('meanTemp',notify, True)

do this POST request:

with the following params:
  • name: function name [mandatory]
  • description: a little function description [mandatory]
  • interval: interval [mandatory]
  • function: path to function file, plese note that the file must be on the server [mandatory]
  • store: if true, store the result into the DB [optional]


        "name": "meanTemp",
        "description": "last hour temp in Bellinzona",
        "interval": 60,
        "function": "path/to/",
        "store": true

Delete notification

It’s possible delete a notification with this DELETE request:



You can delete a notification only if no user are subscribed

List of available notification

To see all available notification function do this GET request:


Register a user

to subscribe to a notification and receive update you must create a user and provide some information to contact you. do this POST request:


with the following params:

  1. username: is the name that will be used to recognise the user [mandatory]
  2. email: a user email [mandatory]
  3. twitter: twitter id, mandatory if you will recieve notification via twitter private message [optional]
  4. tel: mobile phone number, mandatory if you will recieve notification via mobile phone (actually not supported) [optional]
  5. fax, address, zip, city, state, country: additional info about the user [optional]
  6. name, surname: additional info about the user [mandatory]


        "username": "userName",
        "email": "",
        "twitter": "userTwitter",
        "tel": "+41123456789",
        "fax": "+41123456080",
        "address": "via test",
        "zip": "1234",
        "city": "",
        "state": "",
        "country": "",
        "name": "Pinco",
        "lastname": "Pallino"

Delete a user

It’s possible to remove user with this DELETE request:



When you delete a user it automatically unsubscribe from notifications

Subscribe to a notification

To receive notification you must subscribe to an existing notification, do this POST request

with the following params
  1. data: array of how would you like to receive the notification [mandatory]
    "data": ["mail", "twitter"]

Unsubscribe to a notification

Unsubscribe a user from notification with this DELETE request


Check user subscription

Check a user subscription to notification with this GET request


Activate the scheduler

To activate the scheduler move to istsos root filder and run the scheduler script

cd /usr/local/istsos

Store the notification

If you want to store every notification result, set the store flag when you create a new notification.

If you add a new complex notification the function must return the message to save.

def notFunction():

    # get your data

    # check condition

    message = "your message to notify"

    notify = {
        "twitter": {
            "public": message,
            "private": message
           "subject": "mean temp",
           "message": message

    import wnslib.notificationScheduler as nS
    nS.notify('notFunction',notify, True)

    # return the message to save it could be a python dict or a string
    return {"message": message}

Request old notification

To request old notification do this GET request:


by default the system return only the last notification, if you want more notification, or you want to search in a specific period, it’s possible to add some params to the request

  • limit: number, how many response return, if ‘all’ return all notification
  • stime: start date in isoformat (2015-10-01T0:00:00+02:00)
  • etime: end date in isoformat (2015-10-07T16:30:00+02:00)