We are building service that will synchronize with user Google Tasks data, so if user add/edit/delete task in GTask, so it will be added/edited/deleted in our service.
And there is a big problem with synchronization: as I see GTasks API does not provide any onUpdate/onChange event listeners. I mean, the perfect solution can be if there will be Google Tasks API method that can be used to set some callback URL that will be requested when user add/edit/delete tasks.
But I can't find such method in Google Tasks API, so now there is only one very bad way to sync with Google Tasks API - request all users tasks and compare them with service tasks. This is very bad way to sync, because if we have 10k users and want their tasks list be synchronizaed up to 1 minute, so we will need to make > 10k GTasks API requests per minute :(
I hope that I'm wrong and there is some way to set onChange/onUpdate callback for user tasks. Or may be there is some another way to receive actual notification of user GTasks changes(by email & etc).
Does anybody know it? Thank you.
You could use updatedMin parameter to only get Tasks that have been updated since a given timestamp, as described in the documentation.
You should be able to rely on ETag and If-None-Match headers when querying user tasks lists to get a 304 Not Modified if the no tasks in the list have changed. (Not that should also works when polling individual tasks)
This way you can effectively poll for the tasks that have changed since the last time you synced.