How to properly watch for gmail push notifications

Question

I don't understand how to properly watch for gmail push notifications (also i know nothing about the web in terms of coding).

Google give this tutorial page: https://developers.google.com/gmail/api/guides/push

What i did so far:

• Prerequisites: DONE
• Create a topic: DONE
• Create a subscription: DONE
• Grant publish rights on your topic: DONE
• watch() method works and gives this result: {'historyId': '714707', 'expiration': '1618824687477'}

So far everything works fine, but my knowledge stops here. It seems to me that i have to implement some kind of infinite while loop on the watch method, to check for historyId changes. But if so, why would there be a stop() method on the watch() method, and also why would there be a expiration field on the watch result? What should i do from there?

Here is my implementation so far:

from __future__ import print_function
import os.path
from googleapiclient.discovery import build
from google_auth_oauthlib.flow import InstalledAppFlow
from google.auth.transport.requests import Request
from google.oauth2.credentials import Credentials


SCOPES = ['https://mail.google.com/']
MY_TOPIC_NAME = 'my/toppic/name'

creds = None
if os.path.exists('token.json'):
        creds = Credentials.from_authorized_user_file('token.json', SCOPES)
if not creds or not creds.valid:
        if creds and creds.expired and creds.refresh_token:
                creds.refresh(Request())
else:
        flow = InstalledAppFlow.from_client_secrets_file('./my_creds.json', SCOPES)
        creds = flow.run_local_server(port=0)
with open('token.json', 'w') as token:
        token.write(creds.to_json())



gmail = build('gmail', 'v1', credentials=creds)
request = {'labelIds': ['INBOX'],'topicName': MY_TOPIC_NAME}
gmail.users().watch(userId='me', body=request).execute()

Answer 1

I think there is some misunderstanding about the concept of push notifications

• Once you set-up a watch request, push notifications will be automatically received by your application when there is a mailbox update
• A mailbox update takes place for example when you receive a new email
• The historyId in simple words reflects the status of your mailbox at a certain moment (eg when you set-up a watch request)
• This value is only important for reference, because unless specified otherwise you will only get notifications about mailbox updates taking place after the moment corresponding to the specific historyId
• You do not need an endless loop for receiving notifications, you only need to renew the watch request every 7 days .
• Depending on your implementation you will probably need some HTTP library that handles POST requests - whenever the Gmail API posts notifications to your server.