Scheduled push notifications

[marvelm]

Context

I would like to do the following through the dashboard.

1. Send push notifications at a specific local date and time.
2. Send recurring notifications (daily, weekly, monthly).

Implementation

1. The PushController already supports the push_time option and it creates a "scheduled" _PushStatus.

   The scheduling logic should remain separate from parse-server, and it will be the developer's job to create/pick an implementation. This separate program will search for "scheduled" _PushStatus objects and send to devices in timezones for which the pushTime matches the current time. In order to track the delivery/failure rate of notifications, two new fields need to be added to the _PushStatus: sentPerUTCOffset and failedPerUTCOffset.

   These new fields are fully backwards compatible and should not affect parse-server. The only necessary change is adding a field to the dashboard for the user to specify the send time.
   The new schema:

   _PushStatus: {
     // ...
     sentPerUTCOffset: {[key: number]: number},
     failedPerUTCOffset: {[key: number]: number}
   }

2. For this feature, I would like to introduce a new internal class in Parse called _PushCampaign. The pusher will create a _PushStatus object every interval for each _PushCampaign.
   Here's how the schema would look:

   _PushCampaign: {
     state: "active" | "inactive",
     pushStatuses: _PushStatus[], // Pointers
   
     interval: "once" | "daily" | "weekly" | "monthly",
     sendTime: string, // hh:mm:ss
     dayOfWeek: ?number, // when interval = 'weekly',
     dayOfMonth: ?number, // when interval = 'monthly'
   }

   When designing this schema, I researched the available standards for representing repeated intervals and I found that ISO 8601 supports it. However, I couldn't find a mature implementation in javascript. If the situation changes in the future, we can easily deprecate interval, dayOfWeek, and dayOfMonth.

I've been working on a reference implementation of the pusher at @AmpMe/parse-server-scheduled-pusher.

I would appreciate any feedback on this strategy. Thank you for reading.

[flovilmart]

@acinader @felipemobile you may wanna have a look there

[acinader]

@marvelm if you're on AWS, you may want to take a look at: https://www.npmjs.com/package/parse-server-sqs-mq-adapter

Sounds like a nice, well thought out addition to me.

[stale]

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